Title of Invention	A METHOD AND AN APPARATUS TO CONTROL THE DRAFT OF A FIBER MIXTURE
Abstract	The invention relates to a method for controlling the draft of a fiber mixture (F) (e.g. a sliver) of a textile machine (1, 50), with means (222) being provided which detect the fluctuations in mass of the fiber mixture (F) which is supplied to a drafting arrangement unit (1) comprising at least one changeable drafting Zone (HV) which compensates the fluctuations in mass, and a delay time being provided in order to take into account the .' running time of the fiber mixture from the measuring means (222) up to a control application point (R). It has been noticed that the Position of the control application point (R) as well as the value of other control parameters also change with respect to a changed delivery speed (LG) or with respect to any Occurring fluctuations in the mass. This led to losses in quality with respect to the regularity of the formed sliver (F1). A method is therefore proposed whereby for the purpose of changing certain control parameters the delivery speed (LG) of the fiber mixture (F) and/or the comparison of the measured progress of the mass of the fiber material (F1) supplied by the drafting arrangement unit with a predetermined setpoint progress of mass (setpoint) are used. FIG 5.

Title of Invention

A METHOD AND AN APPARATUS TO CONTROL THE DRAFT OF A FIBER MIXTURE

Abstract

The invention relates to a method for controlling the draft of a fiber mixture (F) (e.g. a sliver) of a textile machine (1, 50), with means (222) being provided which detect the fluctuations in mass of the fiber mixture (F) which is supplied to a drafting arrangement unit (1) comprising at least one changeable drafting Zone (HV) which compensates the fluctuations in mass, and a delay time being provided in order to take into account the .' running time of the fiber mixture from the measuring means (222) up to a control application point (R). It has been noticed that the Position of the control application point (R) as well as the value of other control parameters also change with respect to a changed delivery speed (LG) or with respect to any Occurring fluctuations in the mass. This led to losses in quality with respect to the regularity of the formed sliver (F1). A method is therefore proposed whereby for the purpose of changing certain control parameters the delivery speed (LG) of the fiber mixture (F) and/or the comparison of the measured progress of the mass of the fiber material (F1) supplied by the drafting arrangement unit with a predetermined setpoint progress of mass (setpoint) are used. FIG 5.

Full Text	An autoleveller draw frame The invention relates to a method or an apparatus for controlling the draft of a fiber mixture (e.g. of a sliver) of a textile machine, with means being provided to detect the fluctuations in mass of the fiber mixture which is supplied to the drafting arrangement which is at least equipped with a changeable drafting zone which compensates the fluctuations in mass and is provided with a delay time in order to take into account the running time of the fiber mixture from the measuring means to a control application point. Prior literature ("Feedback control systems in modern sizing machines" by Prof. Burgholz - Textilpraxis 1963, July, p. 643) shows a drafting arrangement in which fluctuations in the mass of fiber material supplied to the drafting arrangement are detected by way of a measuring element. The movement of the measuring roller which is produced by the fluctuations in mass is stored via a mechanical storage element and is transmitted in a time-delayed manner to a mechanical device for influencing the draft quantity. A time delay for the control intervention is thus achieved in a mechanical manner, which intervention takes the distance between the measuring place and the actual control application point for the evening of the fiber mixture into account. In newer devices, as have been described in DE-A1-36 19 248 for example, this intermediate storage of the signal of the measuring element is performed electronically. This cited publication states further that the time of delay is corrected according to the magnitude and type of the measured fluctuation in the mass, which means that as soon as the signal of the measured fluctuations in mass is located outside of the normal fluctuations of mass, the draft intervention will occur earlier. This reduces the distance between the control application point and the measuring location of the measuring element. This device allows in particular an improved compensation of sudden fluctuations in the mass of a sliver. EP-A2-803 596 further proposes an apparatus, with a method being proposed for the direct determination of set-points for the control application point of a draw frame. Several measured values of a quality-characterizing value such as the CV value are used in order to determine the optimized parameter such as the control application point in a test run. This optimized control application point is to remain substantially unchanged during the operation. This method, which uses the CV value, leads to disadvantages particularly when the textile machine which is situated upstream of the drafting arrangement is supplied with only one untwisted sliver which shows relatively large fluctuations in mass. An apparatus is further known from EP-A1 533 483, with influencing quantities which influence the measured signal of the measuring member being detected by a fuzz control device and being linked to a knowledge base. A corrective value for the measured signal is produced therefrom. The delivery speed of the fiber material supplied by the drafting arrangement can be used as an influencing quantity for example. This means that the corrective value relates to the respective design of the determined measured value on the basis of influencing quantities and not to the determination of the control application point. For the purpose of correcting the control application point it is proposed in this embodiment that a signal analysis is performed at the drafting arrangement output on the basis of the analysis of the response signal of the measuring element, thus enabling the performance of respective interventions. This means that a correction of the control application point will only be performed at a time when the flaw in the fiber material has already passed through the drafting arrangement and thus can no longer be corrected. Moreover, a further measuring element is required at the output of the drafting arrangement, as well as a complex fuzzy control device. A device is shown in DE-A1-42 15 682 in which a correction of the control application point is performed according to a specific method. The method for the correction of the control application point is only started when there is a transient signal in the measuring element before the drafting arrangement which exceeds a predetermined tolerance value. With the help of the response signal which is detected by a measuring element at the output of the drafting arrangement a respective intervention is performed via the control unit in comparison with the transient signal in order to correct the control application point. This system is not continuously in operation and additionally requires a measuring element at the output of the drafting arrangement. Moreover, a correction of the control application point is only performed when the sliver containing the flaw has already left the drafting arrangement. Examinations have shown that the evenness of the formed sliver, or the CV value and the spectrogram image, changes once the fiber material is supplied to the draw frame at different delivery speeds. This means that one has noticed that the control application point between the two pairs of drafting rollers changes in its position depending on the delivery speed. This fact is usually not disadvantageous in "pure draw frames", because these machines are usually operated with substantially constant speeds. If such a drafting arrangement unit is arranged downstream of a carding machine for further processing of the card sliver, major delivery fluctuations in the drafting arrangement must be expected as a result of the operating procedure in the carding machine. These delivery fluctuations in the carding machine are caused by changes in production, running down the machine during changes of the cans, running in new clothings, and other circumstances. As a result of this frequent change of the delivery speeds there is also a displacement of the control application point with respect to the measuring place before the drafting arrangement. This leads to maintaining an adverser sliver quality in respect to sliver regularity (CV value) and the spectrogram image. This fact is also not considered, or only partly with limitations, by the apparatuses mentioned in connection with the state of the art. Various devices are further known from the state of the art, e.g. from EP-A1 176 661, with the regulation of an autoleveller draw frame being performed on the basis of inlet and outlet measuring element in conjunction with a predetermined setpoint value. In the exhibited example the signal for influencing the control parameters which is measured at the output is used for overall amplification and the runtime of the controlling electronic system. This device is to be used in particular to correct abrupt changes in the supplied fiber mass. This device relates to the matching of the control parameters during the drafting process and not to any principal setting of the control intensity or calibration of the drafting arrangement. Insofar as such a drafting arrangement operates autonomously as a draw frame it was common practice up until now to make respective settings of the control parameters on the draw frame by sliver tests which were performed in a stationary manner in the laboratory. The determined fluctuations in mass were determined in comparison with a predetermined setpoint value (sample sliver) and respective interventions in the control parameters on the drafting arrangement were made. The stopping and renewed start-up of the draw frame to perform such tests and for setting the draw frame did not have any major influence on the productivity or efficiency of the unit. As soon as this drafting arrangement is operated in direct connection with an upstream textile machine (e.g. a carding machine), such sliver tests performed in the lab are not easily possible without reducing the overall efficiency of the entire system. This means that as soon as the sliver tests are performed in a stationary manner in the laboratory it is also necessary to stop the textile machine which is upstream of the drafting arrangement during these tests. When the textile machine concerns a carding machine, it is relatively problematic to put this machine with its relatively large moved masses back into operation again. This means that the efficiency of the system decreases. A device is further known from DE-A1 196 15 947 in which a function is determined on the basis of several CV values whose minimum leads to an optimized parameter such as a control application point or amplification for the control of the draw frame or the carding machine. The optimized parameter is determined in a pre-operational test or setting run of the draw frame or carding machine and maintained during operation in a substantially unchanged way. It is now an object of the present invention to provide a method and an apparatus for setting the drafting arrangement in order to perform optimized control interventions by considering maintaining a high efficiency of the entire plant, particularly when a textile machine is provided directly upstream of the drafting arrangement for the purpose of supplying fiber material. This object is achieved on the one hand in such a way that for changing certain control parameters the delivery speed (LG) of the fiber mixture (7) and/or the comparison between the measured course of the mass of the fiber material (F1) supplied by the drafting arrangement with a predetermined setpoint course of the mass (setpoint) is/are used. The term "delivery speed" relates to the speed of the fiber material which is supplied to the drafting arrangement. The measuring element for detecting the fluctuations in mass is located before the entrance to the drafting arrangement as seen in the direction of conveyance. This device allows that the control intervention is performed at an optimal time, or in an optimized magnitude, in order to completely compensate any fluctuation in mass as determined by the measuring element. The drafting arrangement could be provided with merely one drafting zone (single-zone drafting arrangement) or with several drafting zones (e.g. preliminary draft and main draft). It is preferably proposed that the position of the control application point to the measuring element is corrected depending on the delivery speed of the fiber mixture. It is further proposed that the change in the position of the control application point is performed on the basis of a curve as predetermined by the control unit. This curve was produced first manually on the basis of experimental values and test results and was used by the control unit to determine a corrective value. The curve is determined on the basis of the values (distance of the control application point to the measuring place) and the delivery speed of the fiber material supplied to the drafting arrangement. If a machine (e.g. a carding machine) is provided upstream of the drafting arrangement which supplies the produced fiber material (e.g. the sliver) to the downstream draw frame, it is advantageous to integrate this curve in the control unit of said upstream machine in order to determine the correction of the position of the control application point. This is advantageous because the delivery speed of the supplied fiber material is known to said machine or its control unit or has already been determined there. It is further proposed that the distance of the control application point from the measuring element is reduced with rising delivery speed. For the purpose of considering different fiber materials, it is proposed that several curves can be selected in the control unit according to the selected fiber material. Depending on the fiber feed (staple, mixture, etc.) the drafting characteristics change in the drafting arrangement and thus also the position of the control application point. In order to avoid unnecessarily burdening the regulating device in case of minor fluctuations of the delivery speed, it is proposed that the change in the position of the control application point is only performed when the delivery speed of the fiber mixture leaves a predetermined tolerance threshold. It is further proposed that when comparing the measured course of the mass of the fiber material (F1) as supplied by the drafting arrangement with a predetermined setpoint course of the mass (setpoint), the deviations (a, b) which exceed the tolerance value are used for changing the control parameters (A). The setting of the control intensity is to be understood as the control parameter in particular, which intensity characterizes a value by which the draft is changed into a setpoint mass on the basis of a measured differential signal of the output mass (mean value of the supplied fiber mass). The intervention made on the drafting quantity is to be dimensioned in such a way that the actual value is brought back to the setpoint value. It is preferably further proposed that the course of the mass is depicted in form of a spectrogram which is compared with a standard spectrogram which is predetermined to the control unit. The "term" compared shall be understood in such a way that the determined spectrogram is placed in the control unit by a control program (software) over the standard spectrogram, with the deviations determined from the contour of the standard spectrogram being determined and evaluated via a respective electronic evaluation system. This evaluation device can be used in particular to determine any occurring "peaks" and/or "chimneys" of the actual spectrogram as compared with the standard spectrogram. These evaluations can be used to take measures manually or automatically following the evaluation of the respective progress of the contour of the spectrogram in order to change the control parameters or settings in such a way that on the one hand the determined "peaks and/or chimneys" are avoided and on the other hand the contour of the actual spectrogram approaches the contour of the standard spectrogram or is brought close to a matching. A tolerance field can be provided which allows upward and downward deviations from the course of the standard spectrogram without performing any interventions in the control parameters (e.g. the position of the control application point). This prevents any "build-up process" of the control system. The measures for changing the control parameters can comprise the following: Adjustment of the control intensity, i.e. the determination of the magnitude of the change in draft on the basis of a determined differential signal between actual and setpoint value (mean value of fiber mass), displacement of the control application point to the one or other side, increase of the pressing pressures of the drafting rollers, change of the drafting distance and further measures. The choice of the measure is made on the basis of the evaluation. The control can be based on a catalog of measures (expert system). Preferably, the spectrogram deviations will be used in the range of between 5 and 150 cm period lengths for the measuring process. It is possible with this device to perform purposeful optimizations of the control device without requiring any running down of the upstream textile machine (carding machine) and with simultaneously compensating internal tolerances within the control device. A method is further proposed in which the course of the mass is depicted as a mean value which is compared with a predetermined setpoint value. In particular, this device allows an optimal setting of the control intensity, so that the fluctuations in mass which deviate from the setpoint mean value are returned completely to said value. Measures for the correction of the control devices can be a displacement of the control application point to either the one or the other side or the adjusting quantity of the draft on the basis of a determined differential signal between an actual and a setpoint value. In order to calibrate the effectiveness of the control device with respect to any upward or downward deviation from the setpoint mean value it is proposed that for setting the control parameters the fiber mass supplied to the drafting arrangement is changed per measuring interval. This means that for an evaluation process, the drafting arrangement unit is supplied with an increased fiber mass and with a lower fiber mass for a further measuring process. An error in the mass is intentionally produced in this method by the machine (or apparatus) upstream of the drafting arrangement unit in order to check, or possibly correct, the effectiveness of the control intensity. In addition to the evaluation of the spectrogram with respect to the standard spectrogram, the determined coefficient of variation (CV value) can be used which is compared with a predetermined CV value of the setpoint course of the mass. The length CV value can be used with a length of cut of between 20 cm and 3 m. In order to correct the deviation in the mass (occurring peaks in mass), the displacement of the control application point can be used. Preferably, the fiber mixture is supplied by a carding machine of the drafting arrangement unit. To ensure that the adjustment of the control parameters also meets the needs of the conditions during the working operation, it is proposed that during the run-up of the carding machine a warm-up period is set during which certain monitorings performed by the control unit are ceased. This also relates to such monitorings which measure the course of the mass of the fiber mixture in the drafting arrangement. This means that an adjustment of the control parameters can only be performed following the expiration of the warm-up function. In the cold state the working units via which and between which . the fiber material is conveyed has different processing characteristics which correspond not necessarily to the conditions during operation. Cold rollers can have the tendency for example to extract fibers from the fiber material. This could lead to fluctuations in the mass, however, which are caused merely by the system per se. That is why the calibration of the control devices should be performed under operating conditions, i.e. after the completion of the warm-up phase. After the completion of this phase a length counter can be activated which is provided to supply information about the production. The material produced during the warm-up phase can be deposited in a separate can. This separately stored material can be returned to the blowroom for reprocessing. The warm-up phase can be determined either temporally by a pre-set time value or be monitored, as is proposed further below, by temperature sensors. A sensor for temperature measurement can be attached at a specific roller for example. Once a predetermined temperature has been reached, the control unit is informed that the warm-up phase has been completed, and thus it changes over to the operating phase. The invention is further solved by an apparatus, with means being provided with which the position of the control application point to the measuring element is determined on the basis of the delivery speed of the fiber mixture. These means are preferably formed by a control device, in particular a microcomputer, which causes the initiation of the change in the draft on the basis of data deposited and stored in the control device in conjunction with signals which are transmitted to the control device by a measuring element for the detection of the delivery speed of the fiber material. It is further proposed that the fiber material is supplied from a carding machine to a downstream drafting arrangement unit and the control unit of the carding machine is provided with means in order to transmit a corrective signal to determine the position of the control application point of the downstream drafting arrangement to the control unit of the drafting arrangement to initiate the change in the draft. . The invention is similarly solved by an apparatus, with at least one further means (28) being provided in order to detect the course of the mass of the fiber material (F1) as supplied by the drafting arrangement unit (2) and the signals of the means are transmitted to the control unit (S) which determines the deviations on the basis of a predetermined setpoint value (Soil, M) and produces control signals according to the deviations in order to change certain control parameters. Preferably, the textile machine can be a carding machine. It is further proposed that for setting the control parameters (control intensity) the quantity of the supplied fiber mass is varied by the carding machine for different measurement periods. The speed of the feed roller to the carding machine can be constant and the speed of the doffer can be changed via the control unit. It is similarly possible to change the speed of the feed roller to the carding machine via the control unit and to keep the speed of the doffer constant. In both cases the carding machine will supply more or less fiber material to the downstream drafting arrangement unit following the change of speed. The effects of these different supply quantities with respect to the setting of the control parameters have already been described in the details on the method claims. In order to adjust the measuring periods to the differently supplied fiber quantity it is provided to use a timing element in order to consider the delay time between the start of the changed delivery quantity and the time at which the changed delivery quantity is processed in the drafting arrangement unit. The timing element can be considered within the scope of a software component in the control unit. As has already been described above in closer detail it is proposed that during the runup of the carding machine a warm-up function for the machine is initiated in the control unit which cuts off certain means for monitoring and/or controlling. Means for monitoring the warm-up phase have been provided which are used to release the performance of the adjustment of the control parameters. These means can be temperature sensors which are attached to the carding machine or the drafting arrangement unit. Preferably, the attachment of these sensors is made to the drafting arrangement unit, because it usually has a longer warm-up phase than the carding machine. Further advantages are shown and explained in closer detail by reference to the following embodiments, wherein: Fig. 1 shows a schematic side view of a card with a downstream drafting arrangement unit; Fig. 2 shows a schematic partial view of a drafting arrangement unit with the illustration of the control application point; Fig. 3 shows a spectrogram representation; Fig. 4 shows a diagram for exhibiting the mean value of the fiber mass and the delivery quantity of the carding machine; Fig. 5 shows a schematic representation of a drafting arrangement unit with an inlet measuring element; Fig. 6 shows a quality representation in the form of a spectrogram; Fig. 7 shows a further spectrogram according to fig. 6; Fig. 8 shows a further spectrogram according to fig. 6; Fig. 9 shows a compensating curve for the control for the correction of the control application point; Fig. 10 shows a further diagram according to fig. 9 for different materials, and Fig. 11 shows a schematic side view of a card with a downstream drafting arrangement unit. Fig. 1 schematically shows a carding machine 50 which is provided downstream with a drafting arrangement unit 1 (referred to hereinafter as drafting arrangement) and a sliver coiler 62. The carding machine 50 is provided with a filling box 80 through which the fiber material is supplied to a feed roller 70. The feed roller 70 transfers the fiber material to the downstream licker-in 8 from where the fiber material is supplied to the downstream swift 110. The swift 110 is provided with clothings (not shown in closer detail) which cooperate with clothings of a revolving flat 111 which is arranged above the swift 110. The prepared fiber material then reaches the zone of a doffer 112, it is removed there and reaches a downstream transverse conveyor belt 115 via conveyor rollers 114. The nonwoven supplied by the conveyor rollers 114 to the transverse conveyor belt 115 is formed into a sliver F by the transverse movement of the transverse conveyor belt 115 and transferred to the drafting arrangement 1 by way of the deflection roller 18. In this process the sliver F passes a sensor 17 downstream of the transverse conveyor belt 115 which is in connection with a control unit SE via line 560. The sensor 17 can be equipped with stepped rollers which determine the sliver mass and transmit a signal to the control unit SE. This signal is used for long-term control of the carding machine 50, with a control being applied on the speed of the feed roller 70 which is driven with the drive path 62 and the gear 164. A sliver storage 200 and a measuring element 222 are arranged between the deflection roller 18 and the drafting arrangement 1. The sliver storage 200 is used for compensating differences between the delivery speed of the carding machine and the feed speed of the drafting arrangement which are produced by the control interventions in the inlet zone of the drafting arrangement 1. The sliver storage 200 is connected to the control unit SE with a line 154 through which the degree of filling (e.g. the sag of the sliver loop) in the storage unit 200 is transmitted to the control unit SE. Monitoring sensors (not shown in closer detail) in the storage unit 200 are provided for this purpose. The sensor 222 could be equipped with a pair of sensing rollers for example (as shown in fig. 2), with at least one of the rollers being movably held to scan the sliver mass. The scanned signal is then supplied to the control unit SE via the line 151. The drafting arrangement 1 substantially consists of two drafting zones, the preliminary drafting zone W and the main drafting zone HV. The preliminary drafting zone W is formed by the pairs of rollers 224 and 225 which are fixedly coupled with one another by way of the drive path 43 which is shown schematically. This means that the speed ratio (draft ratio) between the pairs of rollers 224 and 225 is fixedly set. The main drafting zone is situated between the pairs of rollers 225 and 26, with the pair of rollers 26 which is driven by a motor M11 via the gear 140 and the drive path 41 is driven at a constant speed. The motor M11 is driven by the control unit SE via a frequency converter 36. The gear 140 is connected via a drive path 39 with a differential gear 42 which can be overdriven by a servo-motor M2. The servo-motor M2 is controlled by the control unit SE via a frequency converter 37. The change in the speed of the pairs of rollers 224 and 225 with respect to the constant speed of the pair of rollers 26 is performed via the gear 42 and the drive path 43 insofar as a control intervention is required. The sliver F1 formed at the outlet of the drafting arrangement 1 passes through a sensor 28 and reaches the can K via the calender rollers 29 and the funnel wheel 33 where it is deposited in the form of a loop. As is shown schematically, the drive of the calender rollers 29 and the funnel wheel 33 is performed via the drive path 48 which is driven by a gear 45, which on its part is operatively connected with the gear 140 via the drive connection 46. The can plate 34 is also driven by the gear 45 via the drive path 49. As a result of this drive sequence, the drive of the pair of output rollers 26 is coupled with the drive of the can coiler 62 at an evenly remaining drive ratio. The compensation of fluctuations in mass which are transmitted by the sensor 222 to the control unit SE is performed by changes in the speed of the pairs of rollers 224 and 225 through the servo-motor M2, thus changing the draft in the main drafting zone HV. In order to determine the deviations in the mass, a setpoint value (setpoint) is used in the control unit SE which is compared with the actual value. The differences derived therefrom initiate the described control process. As is shown in fig. 2 in particular, the measuring point MS in the pair of sensing rollers 222 is spaced at a distance A from the control application point R. The control application point R is a fictitious point and represents the point at which the control intervention should occur from a temporal point of view in order to compensate the deviation in mass as determined at the measuring point MS. Practical operation has shown that the position of the control application point which is representative of a control parameter depends on several factors. Tolerances within the control system or within the drafting arrangement units also play a role. Furthermore, the level of the pressure load of the press rollers of the pairs of rollers 224 to 26 play a role in the compensation. Similarly, the distance C between the pairs of rollers 225 and 26 must be set accordingly for optimal compensation. Furthermore, the intervention made in the draft quantity on the basis of the determined differential signal between actual and setpoint value represents an important control factor. It is important to include the resulting differential value in such a way in the change of draft, so that a complete compensation of the deviation in mass can be achieved. This means that the evaluation of the determined differential signal and the implementation for the intervention in the draft quantity is of decisive relevance for the result of the control work. This shows that many factors must be considered in order to perform the control work, so that the produced sliver F1 is provided with close to the same quality as a setpoint value sliver. It is therefore necessary to consider the aforementioned factors and to calibrate the autoleveller unit according to the present system. For this purpose a curve of a standard spectrogram 66 is stored in the control unit SE which was formed from a sliver which can be realized from a technical viewpoint and is free from any flaws. The sensor 28 (which can be an inductive sensor for example) is used to determine the spectrogram of the sliver F1 in conjunction with the control unit SE which is shown schematically under no. 67. These two spectrograms 66 and 67 are placed over one another by software routines, thus leading to the illustration according to fig. 3. This shows that the actual spectrogram 67 progresses in this case above the curve of the normal spectrogram. Furthermore, conspicuous elevations can be*seen at two places, with the first elevation being designated as peak 69 and the second elevation as chimney 70. Chimney 70 represents a periodic error. On the basis of this evaluation respective control parameters such as the distance A are changed and a further measurement is performed thereafter. Depending on the evaluation of the deviations from the standard spectrogram, respective interventions in the control parameters can be performed (as described above) in order to perform further measurements subsequently. It is possible to store a catalog of flaws in the system, thus leading to the respective intervention in the control parameters. These adjustments are made until a satisfactory result of the actual spectrogram with respect to the standard spectrogram is obtained. In addition to this spectrogram evaluation it would also be possible to include the CV value into the consideration for setting the control parameters as long as no satisfactory results can be achieved with the first method. Fig. 4 shows a further possibility for adapting the control system. The sliver mass is based on the setpoint mean value MW. In particular, the method as described below can be used to check or set the control characteristics (control intensity) of the control device in case of upward or downward deviations in the predetermined fiber mass. For this purpose several measuring periods are performed. In the exhibited example of fig. 4, a reduced sliver mass (an intentionally produced flaw in the supplied fiber mass) is supplied to the drafting arrangement unit at time T1. Above the course of the mean value of the fiber mass, the broken line shows the fiber mass KM which is supplied to the drafting arrangement unit, with the fiber mass being reduced at time TO. At time T1 the supplied fiber mass has been reduced completely by the quantity X. From this time (T1) onwards the drafting arrangement unit is supplied with the fully reduced fiber mass. The mean value of the reduced sliver mass decreases at first (below the setpoint MW) and is partly compensated in the shown example by the autoleveller device up to a mean value MU. This mean value Mil shows a distance a from the setpoint mean value MW, which shows that the reduced sliver mass was not compensated completely by the autoleveller device. In this case too it is necessary to make settings (as described in the preceding example) in the control parameters in order to obtain the optimal compensation, i.e. the return to the desired mean value MW. The control intensity, i.e. the intervention in the draft quantity, can be changed for example. The intervention in the draft on the basis of the determined mass differential signal is modified or corrected accordingly. In a further measuring interval the delivered quantity from the carding machine to the drafting arrangement can be increased (indicated with the dot-dash line in fig. 4) and the result of the compensation can be verified and corrected by adjusting the respective control parameters. As is also shown with the dot-dash lines, a mean value MO with the distance b from the ideal mean value MW can be obtained, which also entails an adjustment of the control parameters (e.g. control intensity). In performing the different measurements with the different delivered quantities it is also possible to use different measuring lengths of the slivers for determining the mean value. It is therefore possible, by changing the control intensity, by varying the distance A, by changing the axial distance C or by respectively changing the pressure load of the press rollers to perform an optimal setting of the control device. In the illustrated example of fig. 1, a temperature sensor 59 is attached to one of the rollers of the pairs of rollers 114, which sensor supplies its signal to the control unit SE via the line 60. This temperature sensor, which can also be attached at other locations within the carding machine 50, is used to monitor the warm-up function of the machine. This means that during the run-up of the machine (when the cylinders are still cold) various monitoring or control functions are deactivated until a temperature signal is sent by sensor 59 via line 60 which corresponds to a predetermined setpoint value. Only when that has occurred will the length counter for the produced material, the autoleveller device of the carding machine or the downstream drafting arrangement unit 1 and the other monitoring devices be activated. It is necessary to consider that the drafting arrangement unit may require a longer warm-up phase than the carding machine, thus necessitating respective additional time requirements. In this case, the setting of the autoleveller device of the drafting arrangement unit can be performed then. The temperature sensors can also be attached to the drafting arrangement unit. The warm-up function is performed because material can adhere to the cold rollers and the other working members, thus not ensuring optimal operation. The rubber jackets of the press rollers have a different hardness in the cold state than in the warm state, thus leading to different technological preconditions in the drafting work and thus influencing the quality of the produced sliver. The material produced during the run-up phase (warm-up phase) can be deposited in a separate can and thereafter be returned to the blowroom for recycling in the processing process. This device allows making respective calibrations without any laboratory tests during the full operation of the plant in order to perform an optimal setting of the autoleveller device so as to maintain the desired sliver quality. This ensures that the efficiency of the overall plant is maintained. Fig. 9 shows a drafting arrangement unit 1 which consists of two drafting zones, the preliminary drafting zone W and the main drafting zone HV. The preliminary drafting zone is formed by the successive pairs of rollers 3 and 4. The main drafting zone is formed by the pairs of rollers 4 and 5. In these pairs of rollers 3 to 5 the respective lower roller is provided with a drive device which will be described below in closer detail. The respective upper roller of said pairs of rollers usually rest in a pressure-loaded way on the lower rollers and are driven by way of friction. The drafting arrangement unit 1 is provided upstream with a measuring element 7 through which the sliver F is passed before it reaches the drafting arrangement unit. Instead of the single sliver F it would also be possible to supply several slivers situated adjacent to one another. The measuring element 7 consists of a stationary held roller 8 which is also driven by way of a drive which will be described below in detail. Roller 8 is associated with a roller 9 which rests on roller 8 in a spring-loaded manner and is capable of performing evading movements in case of fluctuations in the mass of sliver F. These evading movements are detected in the measuring element 10 and supplied via a timing element Z to the control unit 20. In addition, a sensor 12 is associated with roller 8 which scans the actual speed of said roller and thus the delivery speed of the sliver F to the drafting arrangement unit 1. The signal of the sensor 12 is supplied via line 13 to the control unit 20. A further monitoring element 15 for the formed sliver F1 can be provided downstream of the drafting arrangement unit 1. Said monitoring element 15 is used in particular for monitoring the long-term drifting of the formed sliver and cuts off the machine when the sliver mass migrates outside of the predetermined tolerance range. The measuring element 7 monitors the short-term fluctuations in the sliver and initiates with its signal the control process for changing the draft in order to compensate or control the measured fluctuations in the mass. The control unit 20 controls a main motor M via line 22 which is connected via a drive connection 23 with a main gear 25. Said main gear 25 is connected with a regulating gear 30 (e.g. a differential gear) via the drive connection 27. The overdriving of gear 30 is performed by way of a servo-motor M1 which is connected with the control unit 20 via the path 32. The gear 30 is operatively connected with the lower roller of the pair of roller 4 by way of a drive path 31. A drive path 36 is tapped from drive path 31, leading to the driven rollers of the pairs of rollers 3 and 7. Transmission stages (not shown) can be present in said path 36 in order to consider respective speed ratios. The forward pair of rollers 5 of the drafting arrangement 1 is driven by the main gear 25 via the drive path 35. A setpoint value 38 which is predetermined to the control unit is shown schematically. It is predetermined and is used for setting the draft. The control application point R is situated between the pairs of rollers 4 and 5 at a distance L from the measuring place MS of the measuring element 7. The position of said control application point R determines the time at which the control intervention must be performed in order to compensate the fluctuation in mass as determined by the measuring element 7 by changing the draft. The actual position of the control application point R depends on the technology of the drafting process and is usually located at a close distance from the rear pair of rollers 4 of the main drafting zone HV. Practical experience has shown that the position of said control application point R shifts in the case of changed delivery speed of the supplied fiber material and thus changed production. This was seen in particular during the production and evaluation of a spectrogram (representation of fluctuations of mass in the frequency range), as is shown for example in the figs. 6 to 8. In fig. 6, the amplitude height is entered over a logarithmic scale of lengths (centimeter). This curve rises steeply until reaching a curve peak and then tapers off. This curve representation is designated as ideal and is desirable with respect to the evenness of the sliver. In the diagram according to fig. 7 the delivery speed was reduced and the position of the control application point R to the position of the measuring location MS (distance L) was not changed. This means that merely the time was adjusted due to the lower delivery speed, which time has changed from the measuring location MS until reaching the fixed control application point R. This diagram of fig. 7 shows that the curve now is provided with two elevations, which is indicative of an adverser quality of the formed sliver F1. This means that the evenness of sliver F1 is not constant and there are signs of periodic flaws. The diagram according to fig. 8 shows a curve progress which is obtained during the further reduction of the delivery speed. It can be seen clearly that the second elevation of the curve now already projects beyond the first elevation. This leads to the result that the evenness of sliver F1 has deteriorated even further. Experiments have shown that by changing the position of the control application point R with respect to the measuring location MS during the changed delivery speed LG it is possible to compensate the disadvantageous effects, as is shown in the diagrams according to figs. 7 and 8. This means that by changing the position of the control application point R at changed delivery speed LG it is possible to approximately achieve the optimal curve according to fig. 6. The delay time until the control intervention is adjusted by the correction of the position of the control application point. The results of these examinations are shown in a diagram according to fig. 9, with a curve S being shown which is entered over the delivery speed LG (meters per minute) and the length L (mm), with L representing the distance between the measuring location MS and the control application point R. On the basis of this diagram according to fig. 9, which is schematically shown in fig. 5 as table 40 in the control unit 20, the position of the control application point R can be determined according to the existing delivery speed LG. This leads to the time interval according to which the control intervention must be performed with respect to the measuring location MS. Fig. 9 also shows a tolerance field TG which characterizes a range of the delivery speed in which no correction of the control application point is performed. This tolerance field TG is usually placed in the range of the delivery speed where the work is usually performed most of the time. The tolerance field is to prevent any "building-up process" or overload of the control system. This means that smaller fluctuations in the delivery about a standard value need not necessarily lead to ongoing corrections of the control application points, because they are negligible. The curve S is usually entered with the beginning of the delivery speed = zero and covers the entire spectrum of the possible delivery speed. For the purpose of the run-up from the delivery speed = zero to the operating delivery speed, or in the opposite case for the running down to the delivery speed = zero, it would also be possible to designate certain special ranges in which no correction needs to be made. The control system of the illustrated device will be explained and outlined again below in closer detail: The drive system is set in such a way that the system is operated with a constant draft (different circumferential speeds of the pairs of rollers 4 and 5). The preliminary draft between the pairs of rollers 3 and 4 remains constant. Once any irregularity is determined in the sliver mass (thin or thick place) by means of the roller 9, it is detected k via the measuring element 10 and delivered via line 11 to a timing element Z. The timing element / is usually integrated in the control unit 20 and forms a time delay factor on the basis of the delivery speed until the detected fluctuation in the mass reaches the control application point R and is compensated there by a change in the draft. This compensation of the fluctuation in the mass is performed by using the setpoint value 38 in the control unit 20 which emits a control signal 32 to the servo-motor M1 following the evaluation of the signal. Said motor M1 drives the control gear 30, thus changing the speed of the pair of rollers 4 and thus the draft quantity in the main drafting zone HV. This intervention allows compensating any thick or thin place in the sliver mass. As a result of the illustrated drive connection 36, the drive of the pair of rollers 3 and of the measuring element 7 is entrained according to the changed speed of the pair of rollers 4. As a result, the speed ratio between the pairs of rollers 7, 3 and 4 remain constant. The speed of the pair of rollers 5 which is driven via gear 25 and the drive strand 35 also remains constant. In order to allow setting the time delay precisely via the timing element Z, a sensor 12 is arranged which scans the precise speed of roller 8 of the measuring element 7 and transmits the same via path 13 to the control unit 20. Once the delivery speed of the supplied sliver mass F changes, the control application point R is newly determined in a respective manner by way of the table 40 which is stored in the control unit 20. On the basis of this new determination of the position of the control application point R, the time delay until the actual intervention in the change of the draft is newly determined. Such fluctuations in the delivery speed are present in particular when the drafting arrangement unit is provided upstream with a carding machine in which such production fluctuations (fluctuations in delivery) by various events or measures are normal. Fig. 11 schematically shows such a combination of a carding machine 50 with a downstream draw frame 60. The draw frame 60 is also provided with a drafting arrangement unit 1 which comprises a drive and control device as is described in fig. 5 for example. In addition, said draw frame 60 is provided with a can coiler 62 in which sliver F1 is deposited in can K by way of calender rollers 63 and a funnel wheel 64. As is schematically indicated, the drive of said elements of the can coiler 62 is also taken from the main gear 25. This means that the drive between the can coiler and the forward pair of rollers 5 of the drafting arrangement unit 1 is at a constant ratio. The carding machine 50 is controlled by way of a control unit 51, as is schematically indicated. The sliver F formed in the carding machine is guided through a pair of measuring rollers 53 which monitors the long-term drift of the sliver and transmits respective signals to the control unit 51 via a path 54. These signals are used substantially for controlling the feed roller 55. At the same time, a speed signal can be tapped from said measuring rollers 53 which is also transmitted to the control unit 51 via path 54. The control unit 51 uses this speed signal is to determine the delivery speed LG of the sliver F and to compare it with table 40 which is also stored in the control unit 51. This comparison can then be used to determine from table 40 the actual position of the control application point R of the downstream drafting arrangement unit 1 and to send the same to the control unit 20 via the path 57. This means that the machine (carding machine) which is relevant for the level of the delivery speed also supplies the signal to the downstream control unit for the drafting arrangement 1. Fig. 10 shows a further diagram (the inclusion of specific numbers was omitted) where separate curves S1 to S3 are shown for different materials (staple, type of cotton, etc.) in order to determine the position of the control application point R for the respective material on the basis of the delivery speed LG. In this case, the applicable selection of material is manually entered beforehand. Further embodiments are also possible, in particular in the arrangement of the drive of the drafting arrangement 1. The invention is not limited to the combination of a carding machine and a draw frame. It is also possible to provide other machines upstream of the draw frame. The invention will be used essentially in cases when textile-processing machines are provided upstream of the drafting arrangement unit which are provided with larger fluctuations in production and thus in the delivery speed. With the present invention it is possible to maintain the constancy of the quality with respect to evenness even in the case of major fluctuations in the delivery speed. CLAIMS 1. A method to control the draft of a fiber mixture (F) (e.g. a sliver) of a textile machine (50, 1), with means (222) being provided which detect the fluctuations in mass of the fiber mixture (F) which is supplied to a drafting arrangement unit (1) comprising at least one changeable drafting zone (HV) which compensates the fluctuations in mass, and a delay time being provided in order to take into account the running time of the fiber mixture from the measuring means (222) up to a control application point (R), characterized in that for changing certain control parameters the delivery speed (LG) of the fiber mixture (7) and/or the comparison of the measured progress of the mass of the fiber material (F1) supplied by the drafting arrangement unit with a predetermined setpoint progress of mass (setpoint) are used. 2. The method as claimed in claim 1, characterized in that the position (L) of the control application point (R) to the measuring element (7) is corrected depending on the delivery speed (LG) of the fiber mixture (7). 3. The method as claimed in claim 2, characterized in that the corrective factor for the change in the position of the control application point (R) is taken from a curve (40, S, S1 - S3) which is predetermined to the control unit (20, 51). 4. The method as claimed in claim 3, characterized in that the curve (40, S, S1 - S3) is stored in a control unit (51) of a machine (50) which is provided upstream of the drafting arrangement (60, 1), which machine transfers the fiber mixture (F) produced there to the drafting arrangement (60, 1). 5. The method as claimed in one of the claims 2 to 4, characterized in that the distance (L) of the control application point (R) to the measuring element (7) is reduced with rising delivery speed (LG). 6. The method as claimed in one of the claims 3 to 5, characterized in that several preselectable curves (S1 - S3) according to different fiber materials are stored in the control unit (20, 51). 7. The method as claimed in one of the preceding claims 2 to 6, characterized in that the change of the position (L) of the control application point (R) only occurs when the delivery speed (LG) of the fiber mixture (F) leaves a predetermined tolerance threshold (TG). 8. The method as claimed in claim 1, characterized in that in the comparison between the measured course of the mass of the fiber material (F1) as supplied by the drafting arrangement unit with a predetermined setpoint course of mass (setpoint) the deviations (a, b) which exceed the tolerance value are used for changing the control parameters (A). 9. The method as claimed in claim 8, characterized in that the course of the mass is depicted in the form of a spectrogram (67) which is compared with a standard spectrogram (66) which is predetermined to the control unit (SE). 10. The method as claimed in claim 9, characterized in that the spectrogram deviations are used in the range of between 5 and 150 cm periodic lengths. 11. The method as claimed in claim 8, characterized in that the course of the mass is depicted as a mean value (ML), MO) which is compared with a predetermined setpoint mean value (MW). 12. The method as claimed in one of the claims 8 to 11, characterized in that for setting the control parameters the fiber mass (F) supplied to the drafting arrangement unit (1) is changed per measuring interval (T1). 13. The method as claimed in claim 9 or 10, characterized in that in addition the coefficient of variation (CV value) of the predetermined setpoint course of the mass is compared with the CV value of the measured actual mass and is used for setting the control parameters. 14. The method as claimed in claim 13, characterized in that the length CV value with lengths of cut of between 20 cm and 3 m is used. 15. The method as claimed in one of the claims 8 to 14, characterized in that the control application point (R) is displaced for the correction of the deviation in the mass. 16. The method as claimed in one of the claims 1 to 15, characterized in that the fiber mixture (F) from a carding machine (50) is supplied to the drafting arrangement unit (1). 17. The method as claimed in claim 16, characterized in that during the run-up of the carding machine (50) a warm-up period is set during which certain monitorings of the control unit (SE) are ceased. 18. The method as claimed in claim 17, characterized in that the warm-up period is monitored by temperature sensors (60). 19. The method as claimed in claim 18, characterized in that the warm-up period is determined with respect to time. 20. An apparatus to control the draft of a fiber mixture (F) (e.g. a sliver) which is supplied by a textile machine (50) to a downstream drafting arrangement unit (1), with means (222) being provided which detect the fluctuations in mass of the or fiber mixture (F) which is supplied to a drafting arrangement unit (1) and the drafting arrangement unit is equipped with at least one changeable drafting zone (HV) which compensates the fluctuations in mass and whose draft quantity is controlled via a control unit (SE) on the basis of the determined fluctuations in the mass in comparison with a predetermined setpoint value (setpoint) and on the basis of the delay time between the measuring location (222) and a control application point (R), characterized in that means (20, 51, 40) are provided with which the position (L) of the control application point (R) to the measuring element (7) is determined on the basis of the delivery speed (LG) of the fiber mixture (F). 21. The apparatus as claimed in claim 20, characterized in that the means consist of a control device (20, 51), in particular a microcomputer, which initiates the change in the draft on the basis of the data stored and deposited in the control device (20, 51) in conjunction with signals which are transmitted to the control device by a measuring element (12, 53) to detect the delivery speed (LG) of the fiber material (F). 22. The apparatus as claimed in one of the claims 20 to 21, characterized in that the fiber material (F) is supplied from a carding machine (50) to a downstream drafting arrangement unit (60, 1) and the control unit (51) of the carding machine (50) is equipped with means (40) to transmit a corrective signal to determine the position (L) of the control application point (R) of the downstream drafting arrangement unit (1) to the control unit (20) of the drafting arrangement in order to initiate a change in the draft. 23. An apparatus to control the draft of a fiber mixture (F) (e.g. a sliver) which is supplied by a textile machine (50) to a downstream drafting arrangement unit (1), with means (222) being provided which detect the fluctuations in mass of the fiber mixture (F) which is supplied to a drafting arrangement unit (1) and the drafting arrangement unit is equipped with at least one changeable drafting zone (HV) which compensates the fluctuations in mass and whose draft quantity is controlled via a control unit (SE) on the basis of the determined fluctuations in the mass in comparison with a predetermined setpoint value (setpoint) and on the basis of the delay time between the measuring location (222) and a control application point (R), characterized in that at least one further means (28) is provided in order to detect the course of the mass of the fiber material (F1) as supplied by the drafting arrangement unit (2) and the signals or tne means are supplied to the control unit (S) which determines the deviations on the basis of a predetermined setpoint value (setpoint, M) and produces control signals according to the deviations in order to change certain control parameters. 24. The apparatus as claimed in claim 23, characterized in that the textile machine is a carding machine (50). 25. The apparatus as claimed in one of the claims 23 to 24, characterized in that for the purpose of setting the control parameters the quantity of supplied fiber mass (F) by the carding machine (50) is varied for different measuring periods (T1). 26. The apparatus as claimed in claim 25, characterized in that the speed of the feed roller (8) to the carding machine (50) is constant and the speed of the doffer (112) is changed by the control unit (SE). 27. The apparatus as claimed in claim 25, characterized in that the speed of the feed roller (8) to the carding machine (50) is changed by the control unit and the speed of the doffer (112) is kept constant. 28. The apparatus as claimed in one of the claims 26 to 27, characterized in that a timing element is provided in order to consider the delay time between the start of the altered delivery quantity and the time at which the changed delivery quantity is processed in the drafting arrangement unit (1). 29. The apparatus as claimed in one of the claims 22 to 28, characterized in that during the run-up of the carding machine (50) a warm-up function is initiated by the control unit (SE) for the machine which deactivates certain means for monitoring and/or controlling. 30. The apparatus as claimed in claim 29, characterized in that means for monitoring the warm-up period are provided by means of which the initiation for setting the control parameters is released. 31. The apparatus as claimed in one of the claims 29 to 30, characterized in that the means are temperature sensors (59) which are attached to the carding machine (50) and/or the drafting arrangement unit (1). 32. A method to control the draft of a fiber mixture of a textile machine substantially as herein described with reference to the accompanying drawings. 33. An apparatus to control the draft of a fiber mixture substantially as herein described with reference to the accompanying drawings.

Full Text

An autoleveller draw frame
The invention relates to a method or an apparatus for controlling the draft of a fiber mixture (e.g. of a sliver) of a textile machine, with means being provided to detect the fluctuations in mass of the fiber mixture which is supplied to the drafting arrangement which is at least equipped with a changeable drafting zone which compensates the fluctuations in mass and is provided with a delay time in order to take into account the running time of the fiber mixture from the measuring means to a control application point.
Prior literature ("Feedback control systems in modern sizing machines" by Prof. Burgholz - Textilpraxis 1963, July, p. 643) shows a drafting arrangement in which fluctuations in the mass of fiber material supplied to the drafting arrangement are detected by way of a measuring element. The movement of the measuring roller which is produced by the fluctuations in mass is stored via a mechanical storage element and is transmitted in a time-delayed manner to a mechanical device for influencing the draft quantity. A time delay for the control intervention is thus achieved in a mechanical manner, which intervention takes the distance between the measuring place and the actual control application point for the evening of the fiber mixture into account.
In newer devices, as have been described in DE-A1-36 19 248 for example, this intermediate storage of the signal of the measuring element is performed electronically. This cited publication states further that the time of delay is corrected according to the magnitude and type of the measured fluctuation in the mass, which means that as soon as the signal of the measured fluctuations in mass is located outside of the normal fluctuations of mass, the draft intervention will occur earlier. This reduces the distance between the control application point and the measuring location of the measuring element. This device allows in particular an improved compensation of sudden fluctuations in the mass of a sliver.
EP-A2-803 596 further proposes an apparatus, with a method being proposed for the direct determination of set-points for the control application point of a draw frame.

Several measured values of a quality-characterizing value such as the CV value are used in order to determine the optimized parameter such as the control application point in a test run. This optimized control application point is to remain substantially unchanged during the operation. This method, which uses the CV value, leads to disadvantages particularly when the textile machine which is situated upstream of the drafting arrangement is supplied with only one untwisted sliver which shows relatively large fluctuations in mass.
An apparatus is further known from EP-A1 533 483, with influencing quantities which influence the measured signal of the measuring member being detected by a fuzz control device and being linked to a knowledge base. A corrective value for the measured signal is produced therefrom. The delivery speed of the fiber material supplied by the drafting arrangement can be used as an influencing quantity for example. This means that the corrective value relates to the respective design of the determined measured value on the basis of influencing quantities and not to the determination of the control application point. For the purpose of correcting the control application point it is proposed in this embodiment that a signal analysis is performed at the drafting arrangement output on the basis of the analysis of the response signal of the measuring element, thus enabling the performance of respective interventions. This means that a correction of the control application point will only be performed at a time when the flaw in the fiber material has already passed through the drafting arrangement and thus can no longer be corrected. Moreover, a further measuring element is required at the output of the drafting arrangement, as well as a complex fuzzy control device.
A device is shown in DE-A1-42 15 682 in which a correction of the control application point is performed according to a specific method. The method for the correction of the control application point is only started when there is a transient signal in the measuring element before the drafting arrangement which exceeds a predetermined tolerance value. With the help of the response signal which is detected by a measuring element at the output of the drafting arrangement a respective intervention is performed via the control unit in comparison with the transient signal in order to correct the control application point. This system is not continuously in operation and additionally requires

a measuring element at the output of the drafting arrangement. Moreover, a correction of the control application point is only performed when the sliver containing the flaw has already left the drafting arrangement.
Examinations have shown that the evenness of the formed sliver, or the CV value and the spectrogram image, changes once the fiber material is supplied to the draw frame at different delivery speeds. This means that one has noticed that the control application point between the two pairs of drafting rollers changes in its position depending on the delivery speed.
This fact is usually not disadvantageous in "pure draw frames", because these machines are usually operated with substantially constant speeds.
If such a drafting arrangement unit is arranged downstream of a carding machine for further processing of the card sliver, major delivery fluctuations in the drafting arrangement must be expected as a result of the operating procedure in the carding machine. These delivery fluctuations in the carding machine are caused by changes in production, running down the machine during changes of the cans, running in new clothings, and other circumstances. As a result of this frequent change of the delivery speeds there is also a displacement of the control application point with respect to the measuring place before the drafting arrangement. This leads to maintaining an adverser sliver quality in respect to sliver regularity (CV value) and the spectrogram image.
This fact is also not considered, or only partly with limitations, by the apparatuses mentioned in connection with the state of the art.
Various devices are further known from the state of the art, e.g. from EP-A1 176 661, with the regulation of an autoleveller draw frame being performed on the basis of inlet and outlet measuring element in conjunction with a predetermined setpoint value. In the exhibited example the signal for influencing the control parameters which is measured at the output is used for overall amplification and the runtime of the controlling electronic system. This device is to be used in particular to correct abrupt changes in the supplied

fiber mass. This device relates to the matching of the control parameters during the drafting process and not to any principal setting of the control intensity or calibration of the drafting arrangement.
Insofar as such a drafting arrangement operates autonomously as a draw frame it was common practice up until now to make respective settings of the control parameters on the draw frame by sliver tests which were performed in a stationary manner in the laboratory. The determined fluctuations in mass were determined in comparison with a predetermined setpoint value (sample sliver) and respective interventions in the control parameters on the drafting arrangement were made. The stopping and renewed start-up of the draw frame to perform such tests and for setting the draw frame did not have any major influence on the productivity or efficiency of the unit.
As soon as this drafting arrangement is operated in direct connection with an upstream textile machine (e.g. a carding machine), such sliver tests performed in the lab are not easily possible without reducing the overall efficiency of the entire system. This means that as soon as the sliver tests are performed in a stationary manner in the laboratory it is also necessary to stop the textile machine which is upstream of the drafting arrangement during these tests. When the textile machine concerns a carding machine, it is relatively problematic to put this machine with its relatively large moved masses back into operation again. This means that the efficiency of the system decreases.
A device is further known from DE-A1 196 15 947 in which a function is determined on the basis of several CV values whose minimum leads to an optimized parameter such as a control application point or amplification for the control of the draw frame or the carding machine. The optimized parameter is determined in a pre-operational test or setting run of the draw frame or carding machine and maintained during operation in a substantially unchanged way.
It is now an object of the present invention to provide a method and an apparatus for setting the drafting arrangement in order to perform optimized control interventions by considering maintaining a high efficiency of the entire plant, particularly when a textile

machine is provided directly upstream of the drafting arrangement for the purpose of supplying fiber material.
This object is achieved on the one hand in such a way that for changing certain control parameters the delivery speed (LG) of the fiber mixture (7) and/or the comparison between the measured course of the mass of the fiber material (F1) supplied by the drafting arrangement with a predetermined setpoint course of the mass (setpoint) is/are used.
The term "delivery speed" relates to the speed of the fiber material which is supplied to the drafting arrangement. The measuring element for detecting the fluctuations in mass is located before the entrance to the drafting arrangement as seen in the direction of conveyance.
This device allows that the control intervention is performed at an optimal time, or in an optimized magnitude, in order to completely compensate any fluctuation in mass as determined by the measuring element.
The drafting arrangement could be provided with merely one drafting zone (single-zone drafting arrangement) or with several drafting zones (e.g. preliminary draft and main draft).
It is preferably proposed that the position of the control application point to the measuring element is corrected depending on the delivery speed of the fiber mixture.
It is further proposed that the change in the position of the control application point is performed on the basis of a curve as predetermined by the control unit. This curve was produced first manually on the basis of experimental values and test results and was used by the control unit to determine a corrective value. The curve is determined on the basis of the values (distance of the control application point to the measuring place) and the delivery speed of the fiber material supplied to the drafting arrangement.

If a machine (e.g. a carding machine) is provided upstream of the drafting arrangement which supplies the produced fiber material (e.g. the sliver) to the downstream draw frame, it is advantageous to integrate this curve in the control unit of said upstream machine in order to determine the correction of the position of the control application point. This is advantageous because the delivery speed of the supplied fiber material is known to said machine or its control unit or has already been determined there.
It is further proposed that the distance of the control application point from the measuring element is reduced with rising delivery speed.
For the purpose of considering different fiber materials, it is proposed that several curves can be selected in the control unit according to the selected fiber material. Depending on the fiber feed (staple, mixture, etc.) the drafting characteristics change in the drafting arrangement and thus also the position of the control application point.
In order to avoid unnecessarily burdening the regulating device in case of minor fluctuations of the delivery speed, it is proposed that the change in the position of the control application point is only performed when the delivery speed of the fiber mixture leaves a predetermined tolerance threshold.
It is further proposed that when comparing the measured course of the mass of the fiber material (F1) as supplied by the drafting arrangement with a predetermined setpoint course of the mass (setpoint), the deviations (a, b) which exceed the tolerance value are used for changing the control parameters (A).
The setting of the control intensity is to be understood as the control parameter in particular, which intensity characterizes a value by which the draft is changed into a setpoint mass on the basis of a measured differential signal of the output mass (mean value of the supplied fiber mass). The intervention made on the drafting quantity is to be dimensioned in such a way that the actual value is brought back to the setpoint value.

It is preferably further proposed that the course of the mass is depicted in form of a spectrogram which is compared with a standard spectrogram which is predetermined to the control unit. The "term" compared shall be understood in such a way that the determined spectrogram is placed in the control unit by a control program (software) over the standard spectrogram, with the deviations determined from the contour of the standard spectrogram being determined and evaluated via a respective electronic evaluation system. This evaluation device can be used in particular to determine any occurring "peaks" and/or "chimneys" of the actual spectrogram as compared with the standard spectrogram. These evaluations can be used to take measures manually or automatically following the evaluation of the respective progress of the contour of the spectrogram in order to change the control parameters or settings in such a way that on the one hand the determined "peaks and/or chimneys" are avoided and on the other hand the contour of the actual spectrogram approaches the contour of the standard spectrogram or is brought close to a matching. A tolerance field can be provided which allows upward and downward deviations from the course of the standard spectrogram without performing any interventions in the control parameters (e.g. the position of the control application point). This prevents any "build-up process" of the control system.
The measures for changing the control parameters can comprise the following: Adjustment of the control intensity, i.e. the determination of the magnitude of the change in draft on the basis of a determined differential signal between actual and setpoint value (mean value of fiber mass), displacement of the control application point to the one or other side, increase of the pressing pressures of the drafting rollers, change of the drafting distance and further measures. The choice of the measure is made on the basis of the evaluation. The control can be based on a catalog of measures (expert system).
Preferably, the spectrogram deviations will be used in the range of between 5 and 150 cm period lengths for the measuring process. It is possible with this device to perform purposeful optimizations of the control device without requiring any running down of the upstream textile machine (carding machine) and with simultaneously compensating internal tolerances within the control device.

A method is further proposed in which the course of the mass is depicted as a mean value which is compared with a predetermined setpoint value. In particular, this device allows an optimal setting of the control intensity, so that the fluctuations in mass which deviate from the setpoint mean value are returned completely to said value.
Measures for the correction of the control devices can be a displacement of the control application point to either the one or the other side or the adjusting quantity of the draft on the basis of a determined differential signal between an actual and a setpoint value.
In order to calibrate the effectiveness of the control device with respect to any upward or downward deviation from the setpoint mean value it is proposed that for setting the control parameters the fiber mass supplied to the drafting arrangement is changed per measuring interval. This means that for an evaluation process, the drafting arrangement unit is supplied with an increased fiber mass and with a lower fiber mass for a further measuring process. An error in the mass is intentionally produced in this method by the machine (or apparatus) upstream of the drafting arrangement unit in order to check, or possibly correct, the effectiveness of the control intensity.
In addition to the evaluation of the spectrogram with respect to the standard spectrogram, the determined coefficient of variation (CV value) can be used which is compared with a predetermined CV value of the setpoint course of the mass. The length CV value can be used with a length of cut of between 20 cm and 3 m.
In order to correct the deviation in the mass (occurring peaks in mass), the displacement of the control application point can be used.
Preferably, the fiber mixture is supplied by a carding machine of the drafting arrangement unit.
To ensure that the adjustment of the control parameters also meets the needs of the conditions during the working operation, it is proposed that during the run-up of the carding machine a warm-up period is set during which certain monitorings performed by

the control unit are ceased. This also relates to such monitorings which measure the course of the mass of the fiber mixture in the drafting arrangement. This means that an adjustment of the control parameters can only be performed following the expiration of the warm-up function. In the cold state the working units via which and between which . the fiber material is conveyed has different processing characteristics which correspond not necessarily to the conditions during operation. Cold rollers can have the tendency for example to extract fibers from the fiber material. This could lead to fluctuations in the mass, however, which are caused merely by the system per se. That is why the calibration of the control devices should be performed under operating conditions, i.e. after the completion of the warm-up phase. After the completion of this phase a length counter can be activated which is provided to supply information about the production. The material produced during the warm-up phase can be deposited in a separate can. This separately stored material can be returned to the blowroom for reprocessing.
The warm-up phase can be determined either temporally by a pre-set time value or be monitored, as is proposed further below, by temperature sensors. A sensor for temperature measurement can be attached at a specific roller for example. Once a predetermined temperature has been reached, the control unit is informed that the warm-up phase has been completed, and thus it changes over to the operating phase.
The invention is further solved by an apparatus, with means being provided with which the position of the control application point to the measuring element is determined on the basis of the delivery speed of the fiber mixture.
These means are preferably formed by a control device, in particular a microcomputer, which causes the initiation of the change in the draft on the basis of data deposited and stored in the control device in conjunction with signals which are transmitted to the control device by a measuring element for the detection of the delivery speed of the fiber material.
It is further proposed that the fiber material is supplied from a carding machine to a downstream drafting arrangement unit and the control unit of the carding machine is

provided with means in order to transmit a corrective signal to determine the position of the control application point of the downstream drafting arrangement to the control unit of the drafting arrangement to initiate the change in the draft.
. The invention is similarly solved by an apparatus, with at least one further means (28) being provided in order to detect the course of the mass of the fiber material (F1) as supplied by the drafting arrangement unit (2) and the signals of the means are transmitted to the control unit (S) which determines the deviations on the basis of a predetermined setpoint value (Soil, M) and produces control signals according to the deviations in order to change certain control parameters.
Preferably, the textile machine can be a carding machine.
It is further proposed that for setting the control parameters (control intensity) the quantity of the supplied fiber mass is varied by the carding machine for different measurement periods.
The speed of the feed roller to the carding machine can be constant and the speed of the doffer can be changed via the control unit.
It is similarly possible to change the speed of the feed roller to the carding machine via the control unit and to keep the speed of the doffer constant.
In both cases the carding machine will supply more or less fiber material to the downstream drafting arrangement unit following the change of speed. The effects of these different supply quantities with respect to the setting of the control parameters have already been described in the details on the method claims.
In order to adjust the measuring periods to the differently supplied fiber quantity it is provided to use a timing element in order to consider the delay time between the start of the changed delivery quantity and the time at which the changed delivery quantity is

processed in the drafting arrangement unit. The timing element can be considered within the scope of a software component in the control unit.
As has already been described above in closer detail it is proposed that during the runup of the carding machine a warm-up function for the machine is initiated in the control unit which cuts off certain means for monitoring and/or controlling.
Means for monitoring the warm-up phase have been provided which are used to release the performance of the adjustment of the control parameters. These means can be temperature sensors which are attached to the carding machine or the drafting arrangement unit. Preferably, the attachment of these sensors is made to the drafting arrangement unit, because it usually has a longer warm-up phase than the carding machine.
Further advantages are shown and explained in closer detail by reference to the following embodiments, wherein:
Fig. 1 shows a schematic side view of a card with a downstream drafting
arrangement unit;
Fig. 2 shows a schematic partial view of a drafting arrangement unit with the illustration of the control application point;
Fig. 3 shows a spectrogram representation;
Fig. 4 shows a diagram for exhibiting the mean value of the fiber mass and the delivery quantity of the carding machine;
Fig. 5 shows a schematic representation of a drafting arrangement unit with an inlet measuring element;
Fig. 6 shows a quality representation in the form of a spectrogram;

Fig. 7 shows a further spectrogram according to fig. 6;
Fig. 8 shows a further spectrogram according to fig. 6;
Fig. 9 shows a compensating curve for the control for the correction of the control application point;
Fig. 10 shows a further diagram according to fig. 9 for different materials, and
Fig. 11 shows a schematic side view of a card with a downstream drafting arrangement unit.
Fig. 1 schematically shows a carding machine 50 which is provided downstream with a drafting arrangement unit 1 (referred to hereinafter as drafting arrangement) and a sliver coiler 62. The carding machine 50 is provided with a filling box 80 through which the fiber material is supplied to a feed roller 70. The feed roller 70 transfers the fiber material to the downstream licker-in 8 from where the fiber material is supplied to the downstream swift 110. The swift 110 is provided with clothings (not shown in closer detail) which cooperate with clothings of a revolving flat 111 which is arranged above the swift 110.
The prepared fiber material then reaches the zone of a doffer 112, it is removed there and reaches a downstream transverse conveyor belt 115 via conveyor rollers 114. The nonwoven supplied by the conveyor rollers 114 to the transverse conveyor belt 115 is formed into a sliver F by the transverse movement of the transverse conveyor belt 115 and transferred to the drafting arrangement 1 by way of the deflection roller 18. In this process the sliver F passes a sensor 17 downstream of the transverse conveyor belt 115 which is in connection with a control unit SE via line 560. The sensor 17 can be equipped with stepped rollers which determine the sliver mass and transmit a signal to the control unit SE. This signal is used for long-term control of the carding machine 50, with a control being applied on the speed of the feed roller 70 which is driven with the drive path 62 and the gear 164. A sliver storage 200 and a measuring element 222 are

arranged between the deflection roller 18 and the drafting arrangement 1. The sliver storage 200 is used for compensating differences between the delivery speed of the carding machine and the feed speed of the drafting arrangement which are produced by the control interventions in the inlet zone of the drafting arrangement 1. The sliver storage 200 is connected to the control unit SE with a line 154 through which the degree of filling (e.g. the sag of the sliver loop) in the storage unit 200 is transmitted to the control unit SE. Monitoring sensors (not shown in closer detail) in the storage unit 200 are provided for this purpose. The sensor 222 could be equipped with a pair of sensing rollers for example (as shown in fig. 2), with at least one of the rollers being movably held to scan the sliver mass. The scanned signal is then supplied to the control unit SE via the line 151.
The drafting arrangement 1 substantially consists of two drafting zones, the preliminary drafting zone W and the main drafting zone HV. The preliminary drafting zone W is formed by the pairs of rollers 224 and 225 which are fixedly coupled with one another by way of the drive path 43 which is shown schematically. This means that the speed ratio (draft ratio) between the pairs of rollers 224 and 225 is fixedly set. The main drafting zone is situated between the pairs of rollers 225 and 26, with the pair of rollers 26 which is driven by a motor M11 via the gear 140 and the drive path 41 is driven at a constant speed. The motor M11 is driven by the control unit SE via a frequency converter 36. The gear 140 is connected via a drive path 39 with a differential gear 42 which can be overdriven by a servo-motor M2. The servo-motor M2 is controlled by the control unit SE via a frequency converter 37. The change in the speed of the pairs of rollers 224 and 225 with respect to the constant speed of the pair of rollers 26 is performed via the gear 42 and the drive path 43 insofar as a control intervention is required.
The sliver F1 formed at the outlet of the drafting arrangement 1 passes through a sensor 28 and reaches the can K via the calender rollers 29 and the funnel wheel 33 where it is deposited in the form of a loop. As is shown schematically, the drive of the calender rollers 29 and the funnel wheel 33 is performed via the drive path 48 which is driven by a gear 45, which on its part is operatively connected with the gear 140 via the drive connection 46. The can plate 34 is also driven by the gear 45 via the drive path

49. As a result of this drive sequence, the drive of the pair of output rollers 26 is coupled with the drive of the can coiler 62 at an evenly remaining drive ratio.
The compensation of fluctuations in mass which are transmitted by the sensor 222 to the control unit SE is performed by changes in the speed of the pairs of rollers 224 and 225 through the servo-motor M2, thus changing the draft in the main drafting zone HV. In order to determine the deviations in the mass, a setpoint value (setpoint) is used in the control unit SE which is compared with the actual value. The differences derived therefrom initiate the described control process.
As is shown in fig. 2 in particular, the measuring point MS in the pair of sensing rollers 222 is spaced at a distance A from the control application point R. The control application point R is a fictitious point and represents the point at which the control intervention should occur from a temporal point of view in order to compensate the deviation in mass as determined at the measuring point MS.
Practical operation has shown that the position of the control application point which is representative of a control parameter depends on several factors. Tolerances within the control system or within the drafting arrangement units also play a role. Furthermore, the level of the pressure load of the press rollers of the pairs of rollers 224 to 26 play a role in the compensation. Similarly, the distance C between the pairs of rollers 225 and 26 must be set accordingly for optimal compensation. Furthermore, the intervention made in the draft quantity on the basis of the determined differential signal between actual and setpoint value represents an important control factor. It is important to include the resulting differential value in such a way in the change of draft, so that a complete compensation of the deviation in mass can be achieved. This means that the evaluation of the determined differential signal and the implementation for the intervention in the draft quantity is of decisive relevance for the result of the control work. This shows that many factors must be considered in order to perform the control work, so that the produced sliver F1 is provided with close to the same quality as a setpoint value sliver. It is therefore necessary to consider the aforementioned factors and to calibrate the autoleveller unit according to the present system. For this purpose a

curve of a standard spectrogram 66 is stored in the control unit SE which was formed from a sliver which can be realized from a technical viewpoint and is free from any flaws. The sensor 28 (which can be an inductive sensor for example) is used to determine the spectrogram of the sliver F1 in conjunction with the control unit SE which is shown schematically under no. 67. These two spectrograms 66 and 67 are placed over one another by software routines, thus leading to the illustration according to fig. 3. This shows that the actual spectrogram 67 progresses in this case above the curve of the normal spectrogram. Furthermore, conspicuous elevations can be*seen at two places, with the first elevation being designated as peak 69 and the second elevation as chimney 70. Chimney 70 represents a periodic error.
On the basis of this evaluation respective control parameters such as the distance A are changed and a further measurement is performed thereafter. Depending on the evaluation of the deviations from the standard spectrogram, respective interventions in the control parameters can be performed (as described above) in order to perform further measurements subsequently. It is possible to store a catalog of flaws in the system, thus leading to the respective intervention in the control parameters. These adjustments are made until a satisfactory result of the actual spectrogram with respect to the standard spectrogram is obtained. In addition to this spectrogram evaluation it would also be possible to include the CV value into the consideration for setting the control parameters as long as no satisfactory results can be achieved with the first method.
Fig. 4 shows a further possibility for adapting the control system. The sliver mass is based on the setpoint mean value MW. In particular, the method as described below can be used to check or set the control characteristics (control intensity) of the control device in case of upward or downward deviations in the predetermined fiber mass. For this purpose several measuring periods are performed. In the exhibited example of fig. 4, a reduced sliver mass (an intentionally produced flaw in the supplied fiber mass) is supplied to the drafting arrangement unit at time T1. Above the course of the mean value of the fiber mass, the broken line shows the fiber mass KM which is supplied to the drafting arrangement unit, with the fiber mass being reduced at time TO. At time T1

the supplied fiber mass has been reduced completely by the quantity X. From this time (T1) onwards the drafting arrangement unit is supplied with the fully reduced fiber mass.
The mean value of the reduced sliver mass decreases at first (below the setpoint MW) and is partly compensated in the shown example by the autoleveller device up to a mean value MU. This mean value Mil shows a distance a from the setpoint mean value MW, which shows that the reduced sliver mass was not compensated completely by the autoleveller device. In this case too it is necessary to make settings (as described in the preceding example) in the control parameters in order to obtain the optimal compensation, i.e. the return to the desired mean value MW. The control intensity, i.e. the intervention in the draft quantity, can be changed for example. The intervention in the draft on the basis of the determined mass differential signal is modified or corrected accordingly. In a further measuring interval the delivered quantity from the carding machine to the drafting arrangement can be increased (indicated with the dot-dash line in fig. 4) and the result of the compensation can be verified and corrected by adjusting the respective control parameters. As is also shown with the dot-dash lines, a mean value MO with the distance b from the ideal mean value MW can be obtained, which also entails an adjustment of the control parameters (e.g. control intensity). In performing the different measurements with the different delivered quantities it is also possible to use different measuring lengths of the slivers for determining the mean value.
It is therefore possible, by changing the control intensity, by varying the distance A, by changing the axial distance C or by respectively changing the pressure load of the press rollers to perform an optimal setting of the control device.
In the illustrated example of fig. 1, a temperature sensor 59 is attached to one of the rollers of the pairs of rollers 114, which sensor supplies its signal to the control unit SE via the line 60. This temperature sensor, which can also be attached at other locations within the carding machine 50, is used to monitor the warm-up function of the machine. This means that during the run-up of the machine (when the cylinders are still cold) various monitoring or control functions are deactivated until a temperature signal is sent

by sensor 59 via line 60 which corresponds to a predetermined setpoint value. Only when that has occurred will the length counter for the produced material, the autoleveller device of the carding machine or the downstream drafting arrangement unit 1 and the other monitoring devices be activated. It is necessary to consider that the drafting arrangement unit may require a longer warm-up phase than the carding machine, thus necessitating respective additional time requirements. In this case, the setting of the autoleveller device of the drafting arrangement unit can be performed then. The temperature sensors can also be attached to the drafting arrangement unit. The warm-up function is performed because material can adhere to the cold rollers and the other working members, thus not ensuring optimal operation. The rubber jackets of the press rollers have a different hardness in the cold state than in the warm state, thus leading to different technological preconditions in the drafting work and thus influencing the quality of the produced sliver. The material produced during the run-up phase (warm-up phase) can be deposited in a separate can and thereafter be returned to the blowroom for recycling in the processing process.
This device allows making respective calibrations without any laboratory tests during the full operation of the plant in order to perform an optimal setting of the autoleveller device so as to maintain the desired sliver quality. This ensures that the efficiency of the overall plant is maintained.
Fig. 9 shows a drafting arrangement unit 1 which consists of two drafting zones, the preliminary drafting zone W and the main drafting zone HV. The preliminary drafting zone is formed by the successive pairs of rollers 3 and 4. The main drafting zone is formed by the pairs of rollers 4 and 5. In these pairs of rollers 3 to 5 the respective lower roller is provided with a drive device which will be described below in closer detail. The respective upper roller of said pairs of rollers usually rest in a pressure-loaded way on the lower rollers and are driven by way of friction. The drafting arrangement unit 1 is provided upstream with a measuring element 7 through which the sliver F is passed before it reaches the drafting arrangement unit. Instead of the single sliver F it would also be possible to supply several slivers situated adjacent to one another.

The measuring element 7 consists of a stationary held roller 8 which is also driven by way of a drive which will be described below in detail. Roller 8 is associated with a roller 9 which rests on roller 8 in a spring-loaded manner and is capable of performing evading movements in case of fluctuations in the mass of sliver F. These evading movements are detected in the measuring element 10 and supplied via a timing element Z to the control unit 20. In addition, a sensor 12 is associated with roller 8 which scans the actual speed of said roller and thus the delivery speed of the sliver F to the drafting arrangement unit 1. The signal of the sensor 12 is supplied via line 13 to the control unit 20. A further monitoring element 15 for the formed sliver F1 can be provided downstream of the drafting arrangement unit 1. Said monitoring element 15 is used in particular for monitoring the long-term drifting of the formed sliver and cuts off the machine when the sliver mass migrates outside of the predetermined tolerance range. The measuring element 7 monitors the short-term fluctuations in the sliver and initiates with its signal the control process for changing the draft in order to compensate or control the measured fluctuations in the mass.
The control unit 20 controls a main motor M via line 22 which is connected via a drive connection 23 with a main gear 25. Said main gear 25 is connected with a regulating gear 30 (e.g. a differential gear) via the drive connection 27. The overdriving of gear 30 is performed by way of a servo-motor M1 which is connected with the control unit 20 via the path 32. The gear 30 is operatively connected with the lower roller of the pair of roller 4 by way of a drive path 31. A drive path 36 is tapped from drive path 31, leading to the driven rollers of the pairs of rollers 3 and 7. Transmission stages (not shown) can be present in said path 36 in order to consider respective speed ratios.
The forward pair of rollers 5 of the drafting arrangement 1 is driven by the main gear 25 via the drive path 35.
A setpoint value 38 which is predetermined to the control unit is shown schematically. It is predetermined and is used for setting the draft. The control application point R is situated between the pairs of rollers 4 and 5 at a distance L from the measuring place MS of the measuring element 7. The position of said control application point R

determines the time at which the control intervention must be performed in order to compensate the fluctuation in mass as determined by the measuring element 7 by changing the draft.
The actual position of the control application point R depends on the technology of the drafting process and is usually located at a close distance from the rear pair of rollers 4 of the main drafting zone HV. Practical experience has shown that the position of said control application point R shifts in the case of changed delivery speed of the supplied fiber material and thus changed production. This was seen in particular during the production and evaluation of a spectrogram (representation of fluctuations of mass in the frequency range), as is shown for example in the figs. 6 to 8. In fig. 6, the amplitude height is entered over a logarithmic scale of lengths (centimeter). This curve rises steeply until reaching a curve peak and then tapers off. This curve representation is designated as ideal and is desirable with respect to the evenness of the sliver.
In the diagram according to fig. 7 the delivery speed was reduced and the position of the control application point R to the position of the measuring location MS (distance L) was not changed. This means that merely the time was adjusted due to the lower delivery speed, which time has changed from the measuring location MS until reaching the fixed control application point R. This diagram of fig. 7 shows that the curve now is provided with two elevations, which is indicative of an adverser quality of the formed sliver F1. This means that the evenness of sliver F1 is not constant and there are signs of periodic flaws.
The diagram according to fig. 8 shows a curve progress which is obtained during the further reduction of the delivery speed. It can be seen clearly that the second elevation of the curve now already projects beyond the first elevation. This leads to the result that the evenness of sliver F1 has deteriorated even further.
Experiments have shown that by changing the position of the control application point R with respect to the measuring location MS during the changed delivery speed LG it is possible to compensate the disadvantageous effects, as is shown in the diagrams

according to figs. 7 and 8. This means that by changing the position of the control application point R at changed delivery speed LG it is possible to approximately achieve the optimal curve according to fig. 6. The delay time until the control intervention is adjusted by the correction of the position of the control application point.
The results of these examinations are shown in a diagram according to fig. 9, with a curve S being shown which is entered over the delivery speed LG (meters per minute) and the length L (mm), with L representing the distance between the measuring location MS and the control application point R. On the basis of this diagram according to fig. 9, which is schematically shown in fig. 5 as table 40 in the control unit 20, the position of the control application point R can be determined according to the existing delivery speed LG. This leads to the time interval according to which the control intervention must be performed with respect to the measuring location MS. Fig. 9 also shows a tolerance field TG which characterizes a range of the delivery speed in which no correction of the control application point is performed.
This tolerance field TG is usually placed in the range of the delivery speed where the work is usually performed most of the time. The tolerance field is to prevent any "building-up process" or overload of the control system. This means that smaller fluctuations in the delivery about a standard value need not necessarily lead to ongoing corrections of the control application points, because they are negligible.
The curve S is usually entered with the beginning of the delivery speed = zero and covers the entire spectrum of the possible delivery speed. For the purpose of the run-up from the delivery speed = zero to the operating delivery speed, or in the opposite case for the running down to the delivery speed = zero, it would also be possible to designate certain special ranges in which no correction needs to be made.
The control system of the illustrated device will be explained and outlined again below in closer detail:

The drive system is set in such a way that the system is operated with a constant draft (different circumferential speeds of the pairs of rollers 4 and 5). The preliminary draft between the pairs of rollers 3 and 4 remains constant. Once any irregularity is determined in the sliver mass (thin or thick place) by means of the roller 9, it is detected k via the measuring element 10 and delivered via line 11 to a timing element Z. The timing element / is usually integrated in the control unit 20 and forms a time delay factor on the basis of the delivery speed until the detected fluctuation in the mass reaches the control application point R and is compensated there by a change in the draft. This compensation of the fluctuation in the mass is performed by using the setpoint value 38 in the control unit 20 which emits a control signal 32 to the servo-motor M1 following the evaluation of the signal. Said motor M1 drives the control gear 30, thus changing the speed of the pair of rollers 4 and thus the draft quantity in the main drafting zone HV. This intervention allows compensating any thick or thin place in the sliver mass. As a result of the illustrated drive connection 36, the drive of the pair of rollers 3 and of the measuring element 7 is entrained according to the changed speed of the pair of rollers 4. As a result, the speed ratio between the pairs of rollers 7, 3 and 4 remain constant. The speed of the pair of rollers 5 which is driven via gear 25 and the drive strand 35 also remains constant. In order to allow setting the time delay precisely via the timing element Z, a sensor 12 is arranged which scans the precise speed of roller 8 of the measuring element 7 and transmits the same via path 13 to the control unit 20.
Once the delivery speed of the supplied sliver mass F changes, the control application point R is newly determined in a respective manner by way of the table 40 which is stored in the control unit 20. On the basis of this new determination of the position of the control application point R, the time delay until the actual intervention in the change of the draft is newly determined. Such fluctuations in the delivery speed are present in particular when the drafting arrangement unit is provided upstream with a carding machine in which such production fluctuations (fluctuations in delivery) by various events or measures are normal.
Fig. 11 schematically shows such a combination of a carding machine 50 with a downstream draw frame 60. The draw frame 60 is also provided with a drafting

arrangement unit 1 which comprises a drive and control device as is described in fig. 5 for example. In addition, said draw frame 60 is provided with a can coiler 62 in which sliver F1 is deposited in can K by way of calender rollers 63 and a funnel wheel 64. As is schematically indicated, the drive of said elements of the can coiler 62 is also taken from the main gear 25. This means that the drive between the can coiler and the forward pair of rollers 5 of the drafting arrangement unit 1 is at a constant ratio.
The carding machine 50 is controlled by way of a control unit 51, as is schematically indicated. The sliver F formed in the carding machine is guided through a pair of measuring rollers 53 which monitors the long-term drift of the sliver and transmits respective signals to the control unit 51 via a path 54. These signals are used substantially for controlling the feed roller 55. At the same time, a speed signal can be tapped from said measuring rollers 53 which is also transmitted to the control unit 51 via path 54. The control unit 51 uses this speed signal is to determine the delivery speed LG of the sliver F and to compare it with table 40 which is also stored in the control unit 51. This comparison can then be used to determine from table 40 the actual position of the control application point R of the downstream drafting arrangement unit 1 and to send the same to the control unit 20 via the path 57. This means that the machine (carding machine) which is relevant for the level of the delivery speed also supplies the signal to the downstream control unit for the drafting arrangement 1.
Fig. 10 shows a further diagram (the inclusion of specific numbers was omitted) where separate curves S1 to S3 are shown for different materials (staple, type of cotton, etc.) in order to determine the position of the control application point R for the respective material on the basis of the delivery speed LG. In this case, the applicable selection of material is manually entered beforehand.
Further embodiments are also possible, in particular in the arrangement of the drive of the drafting arrangement 1. The invention is not limited to the combination of a carding machine and a draw frame. It is also possible to provide other machines upstream of the draw frame. The invention will be used essentially in cases when textile-processing

machines are provided upstream of the drafting arrangement unit which are provided with larger fluctuations in production and thus in the delivery speed.
With the present invention it is possible to maintain the constancy of the quality with respect to evenness even in the case of major fluctuations in the delivery speed.

CLAIMS
1. A method to control the draft of a fiber mixture (F) (e.g. a sliver) of a textile machine (50, 1), with means (222) being provided which detect the fluctuations in mass of the fiber mixture (F) which is supplied to a drafting arrangement unit (1) comprising at least one changeable drafting zone (HV) which compensates the fluctuations in mass, and a delay time being provided in order to take into account the running time of the fiber mixture from the measuring means (222) up to a control application point (R), characterized in that for changing certain control parameters the delivery speed (LG) of the fiber mixture (7) and/or the comparison of the measured progress of the mass of the fiber material (F1) supplied by the drafting arrangement unit with a predetermined setpoint progress of mass (setpoint) are used.
2. The method as claimed in claim 1, characterized in that the position (L) of the control application point (R) to the measuring element (7) is corrected depending on the delivery speed (LG) of the fiber mixture (7).
3. The method as claimed in claim 2, characterized in that the corrective factor for the change in the position of the control application point (R) is taken from a curve (40, S, S1 - S3) which is predetermined to the control unit (20, 51).
4. The method as claimed in claim 3, characterized in that the curve (40, S, S1 - S3) is stored in a control unit (51) of a machine (50) which is provided upstream of the drafting arrangement (60, 1), which machine transfers the fiber mixture (F) produced there to the drafting arrangement (60, 1).
5. The method as claimed in one of the claims 2 to 4, characterized in that the distance (L) of the control application point (R) to the measuring element (7) is reduced with rising delivery speed (LG).

6. The method as claimed in one of the claims 3 to 5, characterized in that several preselectable curves (S1 - S3) according to different fiber materials are stored in the control unit (20, 51).
7. The method as claimed in one of the preceding claims 2 to 6, characterized in that the change of the position (L) of the control application point (R) only occurs when the delivery speed (LG) of the fiber mixture (F) leaves a predetermined tolerance threshold (TG).
8. The method as claimed in claim 1, characterized in that in the comparison between the measured course of the mass of the fiber material (F1) as supplied by the drafting arrangement unit with a predetermined setpoint course of mass (setpoint) the deviations (a, b) which exceed the tolerance value are used for changing the control parameters (A).
9. The method as claimed in claim 8, characterized in that the course of the mass is depicted in the form of a spectrogram (67) which is compared with a standard spectrogram (66) which is predetermined to the control unit (SE).
10. The method as claimed in claim 9, characterized in that the spectrogram deviations are used in the range of between 5 and 150 cm periodic lengths.
11. The method as claimed in claim 8, characterized in that the course of the mass is depicted as a mean value (ML), MO) which is compared with a predetermined setpoint mean value (MW).
12. The method as claimed in one of the claims 8 to 11, characterized in that for setting the control parameters the fiber mass (F) supplied to the drafting arrangement unit (1) is changed per measuring interval (T1).
13. The method as claimed in claim 9 or 10, characterized in that in addition the coefficient of variation (CV value) of the predetermined setpoint course of the

mass is compared with the CV value of the measured actual mass and is used for setting the control parameters.
14. The method as claimed in claim 13, characterized in that the length CV value with lengths of cut of between 20 cm and 3 m is used.
15. The method as claimed in one of the claims 8 to 14, characterized in that the control application point (R) is displaced for the correction of the deviation in the mass.
16. The method as claimed in one of the claims 1 to 15, characterized in that the fiber mixture (F) from a carding machine (50) is supplied to the drafting arrangement unit (1).
17. The method as claimed in claim 16, characterized in that during the run-up of the carding machine (50) a warm-up period is set during which certain monitorings of the control unit (SE) are ceased.
18. The method as claimed in claim 17, characterized in that the warm-up period is monitored by temperature sensors (60).
19. The method as claimed in claim 18, characterized in that the warm-up period is determined with respect to time.
20. An apparatus to control the draft of a fiber mixture (F) (e.g. a sliver) which is supplied by a textile machine (50) to a downstream drafting arrangement unit (1), with means (222) being provided which detect the fluctuations in mass of the
or
fiber mixture (F) which is supplied to a drafting arrangement unit (1) and the drafting arrangement unit is equipped with at least one changeable drafting zone (HV) which compensates the fluctuations in mass and whose draft quantity is controlled via a control unit (SE) on the basis of the determined fluctuations in the mass in comparison with a predetermined setpoint value (setpoint) and on the

basis of the delay time between the measuring location (222) and a control application point (R), characterized in that means (20, 51, 40) are provided with which the position (L) of the control application point (R) to the measuring element (7) is determined on the basis of the delivery speed (LG) of the fiber mixture (F).
21. The apparatus as claimed in claim 20, characterized in that the means consist of a control device (20, 51), in particular a microcomputer, which initiates the change in the draft on the basis of the data stored and deposited in the control device (20, 51) in conjunction with signals which are transmitted to the control device by a measuring element (12, 53) to detect the delivery speed (LG) of the fiber material (F).
22. The apparatus as claimed in one of the claims 20 to 21, characterized in that the fiber material (F) is supplied from a carding machine (50) to a downstream drafting arrangement unit (60, 1) and the control unit (51) of the carding machine (50) is equipped with means (40) to transmit a corrective signal to determine the position (L) of the control application point (R) of the downstream drafting arrangement unit (1) to the control unit (20) of the drafting arrangement in order to initiate a change in the draft.
23. An apparatus to control the draft of a fiber mixture (F) (e.g. a sliver) which is supplied by a textile machine (50) to a downstream drafting arrangement unit (1), with means (222) being provided which detect the fluctuations in mass of the fiber mixture (F) which is supplied to a drafting arrangement unit (1) and the drafting arrangement unit is equipped with at least one changeable drafting zone (HV) which compensates the fluctuations in mass and whose draft quantity is controlled via a control unit (SE) on the basis of the determined fluctuations in the mass in comparison with a predetermined setpoint value (setpoint) and on the basis of the delay time between the measuring location (222) and a control application point (R), characterized in that at least one further means (28) is provided in order to detect the course of the mass of the fiber material (F1) as

supplied by the drafting arrangement unit (2) and the signals or tne means are supplied to the control unit (S) which determines the deviations on the basis of a predetermined setpoint value (setpoint, M) and produces control signals according to the deviations in order to change certain control parameters.
24. The apparatus as claimed in claim 23, characterized in that the textile machine is a carding machine (50).
25. The apparatus as claimed in one of the claims 23 to 24, characterized in that for the purpose of setting the control parameters the quantity of supplied fiber mass (F) by the carding machine (50) is varied for different measuring periods (T1).
26. The apparatus as claimed in claim 25, characterized in that the speed of the feed roller (8) to the carding machine (50) is constant and the speed of the doffer (112) is changed by the control unit (SE).
27. The apparatus as claimed in claim 25, characterized in that the speed of the feed roller (8) to the carding machine (50) is changed by the control unit and the speed of the doffer (112) is kept constant.
28. The apparatus as claimed in one of the claims 26 to 27, characterized in that a timing element is provided in order to consider the delay time between the start of the altered delivery quantity and the time at which the changed delivery quantity is processed in the drafting arrangement unit (1).
29. The apparatus as claimed in one of the claims 22 to 28, characterized in that during the run-up of the carding machine (50) a warm-up function is initiated by the control unit (SE) for the machine which deactivates certain means for monitoring and/or controlling.

30. The apparatus as claimed in claim 29, characterized in that means for monitoring the warm-up period are provided by means of which the initiation for setting the control parameters is released.
31. The apparatus as claimed in one of the claims 29 to 30, characterized in that the means are temperature sensors (59) which are attached to the carding machine (50) and/or the drafting arrangement unit (1).

32. A method to control the draft of a fiber mixture of a textile machine
substantially as herein described with reference to the accompanying
drawings.
33. An apparatus to control the draft of a fiber mixture substantially as
herein described with reference to the accompanying drawings.

Documents:

abs-in-pct-2000-805-che.jpg

in-pct-2000-805-che-abstract.pdf

in-pct-2000-805-che-claims filed.pdf

in-pct-2000-805-che-claims granted.pdf

in-pct-2000-805-che-correspondence others.pdf

in-pct-2000-805-che-correspondence po.pdf

in-pct-2000-805-che-description complete filed.pdf

in-pct-2000-805-che-description complete granted.pdf

in-pct-2000-805-che-drawings.pdf

in-pct-2000-805-che-form 1.pdf

in-pct-2000-805-che-form 26.pdf

in-pct-2000-805-che-form 3.pdf

in-pct-2000-805-che-form 5.pdf

in-pct-2000-805-che-other documents.pdf

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Patent Number

211146

Indian Patent Application Number

IN/PCT/2000/805/CHE

PG Journal Number

49/2007

Publication Date

07-Dec-2007

Grant Date

17-Oct-2007

Date of Filing

11-Dec-2000

Name of Patentee

M/S. MASCHINENFABRIK RIETER AG

Applicant Address

Klosterstrasse 20 CH-8406 Winterthur

Inventors:

#	Inventor's Name	Inventor's Address
1	GRESSER, Götz, Theodor	Neumühlestrasse 23 CH-8406 Winterthur
2	MÜLLER, Christian	Brühlbergstrasse 91 CH-8400 Winterthur
3	GRIESSHAMMER, Christian	Bütziackerstrasse 43 CH-8406 Winterthur

PCT International Classification Number

D01H 5/42

PCT International Application Number

PCT/CH99/00255

PCT International Filing date

1999-06-11

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	2507/98	1998-12-18	Switzerland
2	1277/98	1998-06-12	Switzerland