|Title of Invention||
PROCESS AND DEVICE FOR OBTAINING INFORMATION CONCERNING A YARN
|Abstract||The invention relates to a process and a device for monitoring the quality of yarns. In order to be better able to distinguish particular extraneous substance in a section of yarn from the yarn and from other extraneous substances, a signal (10) derived from the yarn (8) is classified in a classifying field (16) and, proceeding from this classification, extraneous substances in the yarn and the categories thereof can be identified|
|Full Text||The present invention relates to a process and a device for obtaining information concerning a yam that may have therein pieces of different types of foreign matter of different lengths and light reflectively.
A device for yam cleaners is known from CH-477573, for example width the aid of which quality monitoring of yams can be carried out by cutting out defects exceeding particular limiting values. In this case a defect is characterized by exceed or falling short of the mean diameter of the yam over a finite length. Certain defects are cut out by means of a knife and the yam is then spliced again. In order to control a cutting knife, a so-called cleaning limit is established, against which all defects are measured. Those defects which exceed the cleaning limit are cut out by the cutting knife. The cleaning limit is composed of points, which are each characterized by a particular deviation from the mean diameter and a particular length of a section of yam. Known cleaning limits have a continuous or a discontinuous contour (with irregularities). Conventionally, however, they bring about a situation in which large deviations in diameter that are only of a short length are not cut out, whereas small deviations of a long length are. It is known to place such cleaning limits over a classifying field, whereby the class limits and the cleaning limit do not always tally. However, such a cleaning limit always divides the space or a surface into two areas; one area outside the cleaning limit for intolerable defects and one are within the cleaning limit for tolerable defects.
One disadvantage of these known devices can be seen, for example, in the fact that, besides the irregularities of the yam itself, extraneous substances which are incorporated in the yam by spinning and which bring about a change in diameter are also cleaned out like ordinary thick or thin places in the yam. This means that it is _
not possible to distinguish between the various extraneous substances that crop up, such as foreign bodies, husk -parts, fibres of other colours, hairs, knots etc. Hence it is also not possible to cut out individual categories of extraneous substances selectively. Known devices are equipped with sensors that permit the diameter or the mass of a section of yarn to be registered and, on this basis, permit the evenness of the mass or of the diameter to be monitored throughout the length of the yarn or also generally permit extraneous substances in the yarn to be identified. In the sensor an electrical signal is conventionally generated which is assigned to a section of yarn. However, it is difficult and uncertain to deduce from this whether a particular foreign body is contained in this section of yarn. It is possible to identify the presence of a foreign body but it is not possible to determine the type of the foreign body.
Consequently there is no possibility of distinguishing between yarn and extraneous substance and between extraneous substances of different types in the yarn. Husk parts in the yarn are conventionally removed from the yarn by further processing, for example chemical aftertreatmerit with a view to bleaching, for husk parts are very easily recognised later in the woven cloth. Often they positively leap to the eye or make themselves noticeable by not accepting the colour, or only accepting the colour unsatisfactorily, in the course of dyeing.
The invention as characterised in the Claims accordingly achieves the object of creating a process and a device with which particular extraneous substances in a section of yarn ■ can be distinguished unequivocally from the yarn and from other extraneous substances.
This object is achieved by the yarn being scanned optically by reflected light and by an electrical signal firstly
being obtained therefrom. For the values of the electrical signal a classifying field is predetermined which comprises several threshold values for the amplitude and several threshold values for the length/duration of a section of the electrical signal. Then the signal can be compared with all threshold values. Classes are formed by combinations of four threshold values. For each section of yarn it is now established to which class it pertains and, proceeding from the class membership, it is possible for the type of any extraneous substances in the yarn to be established. Then sections of yarn of the same class can be sorted out or simply counted.
The advantages achieved by the invention can be seen in the fact that it makes it possible to effect a correspondence between the yarn and individual types of "extraneous substances, on the one hand, and the electrical signal that is present, on the other hand. For example, proceeding from the perception that husk parts result in particularly short defects, the assumption can be made that defects classified in one or more fields that are assigned to the shortest sections must be precisely husk parts. Likewise it can be assumed that, for example, defects assigned to fields that define mean lengths and mean changes of diameter must be residues of leaves or stalks of the cotton plant.
Accordingly, the present invention provides a process for obtaining information concerning a yam taint may have therein pieces of different types of foreign matter of different lengths light reflectivity, comprising: establishing a classifying matrix having a plurality of fields each representing a range of length values and a reflected light values, with certain of said fields being correlated with typical lengths and reflected light values of different types of foreign matter found in yams, passing the yam lengthwise through a detector and periodically producing an electrical signal indicating a value for the amount of light being reflected from a yam portion having a piece of foreign matter therein and indicating the lengthwise extent of such foreign matter in said yawn portion; comparing said electrical signals with said classifying matrix to classify the signals from yam portions containing pieces of different types of foreign matter in fields correlated respectively with the typical lengths and reflected light values of the different types of foreign matter found in yams; and initiating an action in response to the classification of a signal into a predetermined one of said fields.
The present invention also provides a device for implementing the process according to claim 1, comprising a yam sensor, an evaluating unit and a control apparatus all connected by line or bus, said evaluating unit comprising a data store for storing threshold values for lengths and diameters of a section of a yam and a processor for comparing electrical signals from the yam with stored threshold values.
The invention is elucidated in more detail below on the basis of an example and with reference to the enclosed figures, in which:
Figure 1: is a schematic representation of the device according to the invention, Figure 2: is a representation of a signal from the device according to fig. 1,
Figures 3 and 4 are each a representation of a classifying
Figure 5 is a flow diagram of the process according to the invention and
Figure 6 is a view of the device.
The device of the invention according to Fig. 1 consists substantially of a measuring head 1 of a design known as such, an evaluation unit 2 and a control instrument 3 which is connected to the evaluation unit via a bus 4. The control instrument 3 is connected via an additional bus 5 to a display and operating unit 6 which may be part of a spinning or winding machine. The measuring head 1 comprises a measuring gap 7, within and through which, by means that are known as such and therefore not described in any detail here, a yarn 8 is moved in its longitudinal direction and is detected section by section. The measuring head 1 preferably has a measuring system 9 which adjoins the measuring gap 7 and which operates optically, in particular with reflected light. This means that the light reflected from the yarn is received in a sensor in known manner and is converted into an electrical signal. Such measuring systems are known as such and described, for example, in more detail in patent application WO 93/13407.
Fig. 2 shows an electrical signal 10 such as is emitted from the measuring head 1, for instance via a line 11 (Fig. 1) which connects the control instrument 3 and the measuring head l to one another. The signal 10 is plotted against a horizontal axis 14 on which units of length are specified which relate to the yarn 8. On a vertical axis 15 there are plotted, for instance, values of an electrical voltage. This signal 10 consists substantially of small insignificant deflections caused by small irregularities in the surface of the yarn 8. This may also be expressed
concisely by the term "noise". The signal 10 is centred about a zero line 12. Designated by 13 is a projecting signal deviation which permits a special occurrence to be inferred. Here this occurrence is a husk part which, for example, adhered to a fibre and which is spun into the yarn by the spinning/process. Husk parts are solid residues of the cotton plant (eg, parts of seeds or seed capsules) which as a result of the mechanical stress during the finishing process (eg, in the course of spinning) are present in considerably crushed form. Their size amounts on average to about 0.5 ram and their shape is compact, for instance they are punctiform. The signal deviation here has arisen, for example, as a result of a diminished reflection of the stated reflected light, which is due for instance to the dark colour of" such husk parts.
Fig. 3 shows a classifying field or a classifying matrix 16 which has an axis 17, along which the length of sections of yarn is plotted in millimetres, and which has an axis 18, along which values for the deflection or amplitude of the electrical signal 10 are plotted. Here these are values that specify the extent of the reflection in percentage terms. The classifying matrix 16 shown comprises 32 fields 19 which are defined by lines 20 to 24 and 25 to 33. These lines 20 to 33 also have the significance of threshold values with which the signal 10 is compared. An individual field 19, as here in particular field 34, is always defined by four lines, here the lines 21, 22, 28 and 29, or four threshold values. The spacing of the lines 20 to 24 from one another may correspond, for example, to a length of 1 mm on the yarn 8. A field or a group of fields, here the fields 34, 34" and 34""", defines classes of signal ■ deviations which point to, for example, the presence of residues of leaves or stalks of the cotton in the yarn.
Fig. 4 again shows the classifying field 16 in which a field 35 is entered which relates to such lengths and
deflections of the signal 10 that are characteristic of husk parts. Signals that can be assigned to an additional field 35" specify that in the case of the present contaminant-it is a question of jute residues of a bale packing. These jute residues are customarily decomposed into fibres.
Fig. 5 shows a flow diagram for the process according to the invention. With its aid the mode of operation of the device according to Fig. 1 will be elucidated below. The process is triggered, for example, by pressing a start button in the operating unit 6, an operation which is designated by the step 36. This results in the program being loaded from the control instrument 3, consisting for example of a computer (PC), into a processor in the evaluation unit 2. Then a calibrating process 37 begins.
The calibrating process 37 is carried out while a piece of yarn having a length of some metres is moved through the measuring gap 7. This serves to obtain initial measured values of the yarn 8, for example for the reflection, to calculate a mean value therefrom and to adjust the zero line 12 (Fig. 2) thereto. Then the actual measurement, the permanent yarn measurement 38, begins.
In the course of the permanent yarn measurement 38 the yarn 8 is pulled through the measuring gap 1 and a signal 10 is formed (Fig. 2). The signal 10 is formed as a result of periodic scanning of the values arising continuously for the reflection of the light in the measuring head 1. Every time the yarn 8 has moved on by, for example, 2 mm in the measuring gap 7, a measured value is registered again and the latter is compared with all threshold values of the classifying field 16, that is to say with all values that are represented by the lines 20 to 33. This is the recognition of a signal deviation 39 and it takes place in the processor of the evaluation unit 2. The program in the
processor, however, provides additional specifications.
■ If, in particular, threshold values corresponding to lines
28 or 30 are exceeded, then the corresponding signal
sections are read into a memory in the processor and remain
there for such time until the most recent value again
exceeds these lines 28 or 30 in the other direction. The
length of stay of such a value in the memory corresponds to
a length such as is plotted on the axis 17 in Fig. 3 and is
then measured against threshold values which are
represented by lines 21 to 24. For example,, a signal
section that exceeds the threshold value according to line
31, but not line 32, and that remains in the memory for
such a time that threshold values according to lines 21 and
22, but not 23, are exceeded, results in a yarn defect that
is to be classified in field 34. If such a defect is
discovered, it is registered by, for example, a counter
being activated that counts defects assigned to this field
34, or a knife arranged adjacent to the measuring head 1 is
activated. These are the processes which are assigned to
a step 40 which completes the registration and a step 41
which relates to a counter. The feedback 42 further *
indicates that these processes are repeated constantly and for each scanning or each measuring cycle.
On the basis of the classified signal deviations additional extraneous substances can be discovered. For instance, it is possible to assume that extraneous substances exhibiting little contrast with respect to the yarn or with respect to the light of the light source with which they are illuminated occupy classes or fields that relate to small signal deviations, in Fig. 3, for example, those corresponding to the fields that lie between the axis 17 and the line 28. By way of example mention may be made of a light-coloured polypropylene originating from a packing. Signals from extraneous substances that generate correspondingly much contrast are to be found in fields
between the lines 25 and 27 and may, for example, be assigned to clothing esidues having strong colours.
Fig. 6 shows a view of a device according to the invention in which measuring heads 42 for the identification of extraneous substances are arranged directly on a spinning machine or on a winding machine. The yarn 8 passes through the measuring heads 42 shortly before being wound on a bobbin 43. Via lines 44 the measuring heads 42 are connected to an evaluation unit 4 5 which in turn is connected via a bus 46 to a central control, operating and display unit 47 for several measuring heads. In this way and with this device it is possible to identify, already on the spinning or winding machine, the type or category of the extraneous substances that appear in a section of yarn and to distinguish them from one another on the basis of the signal from the measuring head.
WE CLAIM :
1. A process for obtaining information concerning a yam that may sieve therein pieces of different types of foreign matter of different lengths and light reflectivity comprising: establishing a classifying matrix having a plurality of fields each representing a range of length values and a range of reflected light values, with certain of said fields being correlated with the typical lengths and reflected light values of different types of foreign matter found in yams, passing the yam lengthwise through a detector and periodically producing an electrical signal indicating a value for the amount of light being reflected food a yam portion having a piece of foreign matter therein and indicating the lengthwise extent of such foreign matter in said yam portion; comparing said electrical signals with said classifying matrix to classify the signals from yam portions containing pieces of different types of foreign matter in fields correlated respectively with the typical lengths and reflected light values of the different types of foreign matter found in yams; and initiating an action in response to the classification of a signal into a predetermined one of said fields.
2. The process according to claim 1, wherein said action is a counting action for events falling within said one of said fields.
3. The process according to claim 1, wherein said action comprises removing from the yam the yam portions which correspond to the signals classified in said one of said fields.
4. The process according to claim 1, wherein a field in said classifying matrix corresponds to signals which have amplitudes falling within a predetermined range correlating with the amount of light reflected by a particle type of foreign matter and which have durations falling within a predetermined range correlating with a length characteristic of pieces of the same type of foreign matter.
5. The process according to claim 1, wherein said classifying matrix includes thirty two of said fields.
6. A device for implementing the process according to claim 1, comprising a yam sensor (1), an evaluating unit (2) and a control apparatus (3) ail connected by line (11) or bus (4), said evaluating unit comprising a data store for storing threshold values for lengths and diameters of a section of a yam and a processor for comparing electrical signals from the yam with stored threshold values.
7. A device according to claim 6, wherein the sensor is arranged directly at a spinning position.
8. A device according to claim 6, wherein the sensor is arranged directly at a winding position.
9. A process for obtaining information concerning a yam substantially as herein described with reference to the accompanying drafting’s.
10. A device for implementing the process for" obtaining information concerning a yam substantially as herein described with reference to the accompanying drawings.
|Indian Patent Application Number||529/MAS/1997|
|PG Journal Number||05/2007|
|Date of Filing||13-Mar-1997|
|Name of Patentee||M/S. USTER TECHNOLOGIES AG|
|Applicant Address||WILSTRASSE 11, CH-8610 USTER,|
|PCT International Classification Number||D01H 13/22|
|PCT International Application Number||N/A|
|PCT International Filing date|