|Title of Invention||
METHOD FOR MONITORING THE APPLICATION OF PARAFFIN ON A RUNNING YARN
|Abstract||In order to improve the running and sliding properties of the yarn during its further processing, in particular for machine- knitting and knitting, it is waxed during rewinding in bobbin winding machines by passing it along a paraffin body. When the paraffin body is used up without this being noticed, the unwaxed yarn can cause yarn breaks or even needle breakages, which leads to production errors or lost production. It is therefore proposed to monitor the slippage at the winding stations where, to prevent pattern windings, the drive of the friction drum is switched on and off at intervals in such a way, that acceleration phases with slippage between the friction drum and the bobbin and slippage- free run-out phase follow each other. If the slippage decreases in successive acceleration phases and remains at a low level, while the drive output of the friction drum remains unchanged, this is considered to be an outage of the paraffin application.|
|Full Text||METHOD FOR MONITORING THE APPLICATION OF PARAFFIN
ON A RUNNING YARN
FIELD OF THE INVENTION
The invention relates to a method for monitoring the application of paraffin to a running
yarn at a winding station of a cheese-producing textile machine.
BACKGROUND OF THE INVENTION
It might be necessary to reduce the coefficient of friction of the yarn in connection with
processing it. A known method for doing this is the application of paraffin. The running and
sliding properties, in particular for machine-knitting and knitting, are considerably improved by
the paraffin particles applied to the yam. The application of paraffin takes place, for example, on
bobbin winding machines during the rewinding of the yarn from cops to cheeses. In the process,
the yam is brought into contact with a paraffin body, which is used up by removal of the paraffin.
When a paraffin body is used up, or its contact with the yarn is interrupted, but not detected,
the unwaxed yarn can cause yam breaks during subsequent processing, or even needle breakage
of a knitting machine, which leads to production errors or lost production. Therefore various
methods and devices have already been proposed, which make monitoring of the paraffin
application to the yam possible.
Most methods are based on monitoring the paraffin body itself and signaling when it is
detected that it is used up. It is disadvantageous here that the contact of the paraffin body with
the yarn can also be disrupted if the paraffin body is not used up, but only being jammed or dirty.
A method and a device are described in German Patent Publication DE 195 47 870 Al, by
means of which the result of waxing can be checked. To this end heat sensors arc arranged in the
course of the yarn before and behind the paraffin application device, which are charged with
sliding friction by the running yarn. Each increase in friction exceeding a defined value is
interpreted as a defect in the paraffin application device, which results in switching of the
Additional sensors are required for the known method and the known device, whose
employment as a rule is not anticipated in a bobbin winding machine. It is therefore necessary to
adapt the signal processing to these sensors.
OBJECT AND SUMMARY OF THE INVENTION
It is the object of the present invention to perform the monitoring of the paraffin application
to a running yam by means which are already employed for monitoring the ongoing winding
This object is attained with the aid of the characterizing features of claim 1. Advantageous
embodiments of the method are claimed in the dependent claims.
If the friction drum and the bobbin run at the same angular speed, or if the angular speeds
have a definite ratio, for example 1 :1.5, which causes strong patterns, the layers of yarn are
placed on top of each other. Because of this the reversing points are also located on top of each
other. This leads to the unwanted formation of bulges on the surface of the bobbin, so-called
pattern windings. The build-up of pattern windings can be effectively reduced by a changing
slippage between the friction drum and the bobbin. Changing slippage can be generated by the
acceleration in intervals of the friction drum. With an unchanged drive output, the slippage
changes with the increase in the bobbin diameter and therefore increasing mass of the bobbin. In
accordance with the invention it is only assumed that the paraffin application has failed when the
deposit shift on the surface of the cheese noticeably changes during successive acceleration
phases of the cheese.
The drive of the bobbin takes place by friction by means of the friction drum. When the
friction drum is accelerated, based on the slippage, the circumferential speed of the bobbin lags
more or less behind the circumferential speed of the friction drum. Pattern disruption is effected
by means of this slippage. The frictional force, and therefore the drive moments on the bobbin
are functions of bobbin-technological parameters, such as contact pressure compensation, type of
yarn, mass of the bobbin, yarn preparation, etc.
Sensors are applied to the friction drum as well as to the holder of the cheese in the winding
frame, by means of which the angle of rotation, and therefore the angular speed, or
respectively the length of the rotation period, of the two rotating bodies is continuously
determined. Customarily this is used for detecting the diameter of the cheese, which
continuously changes during the bobbin travel. Within the scope of the invention, these
sensors are also employed for monitoring the paraffin application. Here, the invention
is based on the knowledge that if the paraffin application fails, the yarn, which
increasingly covers the surface of the cheese because of the traversing lift, significantly
changes the frictional behavior of the cheese surface after already a short time.
If the paraffin application stops in the course of a bobbin travel, the change in the
frictional behavior of the bobbin travel can be easily detected. But since the frictional
behavior of the bobbin surface formed by a waxed yarn is normally known as a
function of the winding station, the batch and the winding parameters, at the latest after
the batch has been running for a while, it is also possible after a cheese change to detect
that the frictional behavior of the cheese surface is outside of expected values.
To prevent an extended unwaxed length of yarn from collecting on the cheese, it
is provided in accordance with the invention to immediately stop the winding station
after the loss of paraffin application has been detected. But it would also be possible,
however with incurring losses, to finish the winding of the cheese and to subsequently
remove it as an off-standard bobbin.
It is useful to emit a signal by which the operator is called when the winding
station is stopped. The operator can then initiate appropriate steps for restoring the
correct application of paraffin.
If, in regard to the further processing of the yarn wound on the cheese, there
should be the requirement of avoiding even short yarn sections lacking paraffin, after
stopping the winding station it is possible to draw off the unwaxed yarn section from
the reversely rotating cheese by means of the suction nozzle, or even by hand.
The absolute size of the slippage between the friction drum and the bobbin
occurring during the acceleration phases during pattern disruption is a very essential
measurement for determining the frictional behavior of the cheese on the friction drum.
The slippage between the cheese and the friction drum is determined and evaluated as a
value which is proportional to the coefficient of friction after friction drum. It can be
determined by the evaluation of the angular velocities, or respectively lengths of the
rotation periods, of the friction drum and the cheese. However, to determine this
slippage, the bobbin diameter, which continuously
changes in the course of the cheese travel, must be calculated in a known manner and in the way
already explained above. This calculation cannot be performed during the acceleration phases,
since during this time a false diameter would be determined because of the slippage. For this
reason, the diameter of the bobbin is calculated in the acceleration-free run-out phases, and the
course of increase of the bobbin diameter for the acceleration phase is precalculated based on the
previous values. The size of the slippage in the slippage phases can be quantitatively determined
from the difference between the bobbin diameter distorted by the slippage and the actual value of
the bobbin diameter.
If then the slippage decreases in sequential acceleration phases, while the drive output
remains unchanged, and remains on a low level, in accordance with the invention this is a signal
that no paraffin was applied to the yarn. The coefficient of friction, and therefore the frictional
force, have increased. This increase can be noted so clearly that its association with the paraffin
application is easily possible.
If in addition the detected frictional force, which is transmitted by means of the drive
moment from the friction drum to the bobbin, is included in the evaluation, statements regarding
the frictional behavior of the surface of the cheeses can be made even more distinctly. If in the
slippage-free run-out phases of the two rotating bodies their deceleration within the scope of the
pattern interruption is additionally determined, losses due to friction, inertia and convection, as
well as load moments, the latter caused for example by the yam tensile force of the yarn being
wound, can be determined. But these are also present in the acceleration phases. It is possible to
determine parameters in this way which have no connection at all with the frictional behavior of
the surface of the cheese on the friction drum. By means of this, the lack of paraffin application
becomes noticeable even faster and clearer. Most of all it is possible by means of this to
differentiate the position of the function of the frictional force as a function of the slippage
clearly in accordance with the criteria of paraffin application/no paraffin application already at
the start of the bobbin travel.
If a sensor for the tensile force of the yarn is provided at the winding station, its yield values,
which constitute the load moment of the two rotating bodies, can alternatively be included in the
evaluation. By means of this it is at least prevented that fluctuations of the tensile yarn force
distort the result of the slip determination.
The deposit shift, which corresponds to the displacement of a reversing point of the yarn
deposit on a circumferential line on the bobbin in respect to the preceding reversing
point, is determined as a function of the slippage and is used for evaluating the frictional
behavior of the surface of the cheese on the friction drum. Not only is the respectively
absolute slippage size included in the evaluation by determining the deposit shift, but also
the result of the slippage, so that the slippage course, including the length of the slippage,
is determined. The inclusion of this additional dimension also leads to more significant
deviations, in this case in the function of the deposit shift as a function of the slippage, in
contrast to an isolated consideration of the slippage.
An improvement of the ability to make a statement regarding the paraffin
application can also be achieved in that a reference value is determined by averaging the
frictional behavior of the cheeses at several winding stations, from which a certain
measurement of a deviation is defined as the lack of paraffin application.
The invention will be explained in greater detail by means of exemplary
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Fig. 1 represents a winding arrangement with an evaluation device for determining
Fig. 2 represents the structure of an evaluation device in a block circuit diagram;
Fig 3 shows a diagram as a small portion of a bobbin travel for explaining the present
Fig. 4 is a diagram of the slippage occurring between a friction drum and a bobbin during
the portion of the bobbin travel in Fig. 3, wherein the slippage is scaled to the diameter of
Fig. 5 represents the course of the diameter in an acceleration run-out diagram of a
Fig. 6 represents the equalized run-out process of a conical bobbin;
Fig. 7 shows a diagram wherein the relative deposit shift has been applied over the
respectively for a waxed and an unwaxed yarn, and
Fig. 8 shows a diagram wherein the frictional force has been applied over the slippage,
respectively for a waxed and an unwaxed yarn.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The winding device, in particular the winding device of a winding station of a bobbin
winding machine, represented only schematically in Fig. 1, has a friction drum 10 driven by
means of a drive motor 11. The friction drum 10 is provided with a reverse thread groove 12, so
that it is simultaneously used as a traversing device for a yarn 15, which is running in the
direction of the arrows over a sensor 13 for the tensile force of the yarn through a yam eye 14.
The yarn 15 is wound onto a bobbin tube 16 as a random wound bobbin, so that a so-called
cheese 17 is created. Since the invention is applicable both to the production of cylindrical
cheeses as well as to the production of conical cheeses, a cylindrical cheese 17 is represented in
Fig. 1, and a conical cheese 17 in Fig. 2. If in what follows mention is made of a bobbin radius
or bobbin diameter, in connection with a conical cheese 17 the neutral diameter or the so-called
driving diameter is meant. The bobbin tube 17 is held by means of two bobbin plates 18,19,
which respectively engage the open ends of the tube 16 in a frictionally connected manner by
means of a cone 20,21. The bobbin plates 18,19, which rotate with the tube 16, and therefore
with the bobbin 17, are seated in a bobbin frame, not represented, which is pivotable around an
axis which is parallel with the shaft 22 of the friction drum 10.
A sensor 23 which, for example, is designed as an angle encoder, is associated with the shaft
22 of the friction drum 10. The angular speed, the period length or the rpm of a friction drum are
detected by means of this sensor 23. A sensor 24, which is also designed as an angle encoder, is
associated with the bobbin plate 16. The respective measured values of the bobbin 17 are
detected by means of this sensor. The signals of the sensors 23 and 24 are detected in a control
and evaluation device 25.
To prevent pattern windings in the course of the production of the bobbin 17, a so-called
pattern disruption is performed, during which slippage between the friction drum 10 and the
bobbin 17 is intermittently generated. This is achieved in that the drive motor 11 of the friction
drum 10 is altematingly switched on and off. If, after the drive motor 11 having been shut off,
the rpm of the friction drum 10 fall below a predetermined value, the drive motor 11 is switched
on again, by means of which the friction drum 10 is accelerated up to maximum rpm. Thereafter
the drive motor 11 is switched off again, after which the process is repeated. Because of the
mass inertia of the bobbin, a slippage between the friction drum 10 and the cylindrical bobbin 11
is created during the acceleration of the friction drum 10.
Starting from the bobbin tube 16, which initially is seated empty against the friction drum
10, the radius or diameter of the bobbin increases because of the yarn 15 wound thereon, until the
bobbin 17 has reached its maximum radius or diameter.
The bobbin radius r,p can be calculated, based on the signals of the sensors 23,24, in
accordance with the following equation:
The following meanings apply here:
arp angular speed of the bobbin
afw angular speed of the friction drum
rsp radius of the bobbin
rfw radius of the friction drum.
If this calculation is continuously performed at short time intervals, for example at time
intervals of 0.1 s, a curve results such as is represented in Fig. 3 as a diameter (2 x rsp) over the
Fig. 3 shows a diameter increase of approximately 0.75 mm in the range of a bobbin
diameter of approximately 155.15 to approximately 155.9 mm during a time of approximately 17
seconds. The lower sections of this curve correspond to the run-out phases in which the drive
motor 11 of the friction drum 10 is switched off, so that in case of a cylindrical bobbin geometry
the friction drum 10 and the bobbin 17 run tree of slippage. Therefore the mentioned equation
can be applied in these run-out phases 30, so that the course of the curve represented in the run-
out phases 30 corresponds to the actual course of the increase of the bobbin radius rsp, or here of
the diameter. In the acceleration phases 31 located between the run-out phases 30, the bobbin 17
has a lower circumferential speed than the friction drum 10. There, the calculation of the bobbin
radius rsp or of the bobbin diameter leads, by means of the mentioned equation, to a fictitious
bobbin diameter or bobbin radius, which is distorted by the occurring slippage. Because of the
slippage, an increase in the bobbin radius or bobbin diameter is calculated by means of the above
equation, which is larger than the actual course of increase of the bobbin diameter in the
acceleration phase 31. vsp = (l-S)xvtr applies to the bobbin speed, S here represents the
The drum speed vtr and the bobbin radius rsp can be provided as known values in the winding
process. Therefore: asp x tsp = (1 - S) x vtr,
In the acceleration phases, the bobbin radius is calculated as a so-called distorted bobbin
asp, s _ 0 means: on the condition that the slippage = 0.
Therefore, the following relationship results for the slippage between the drum and the
Taking into account the course of the increase of the bobbin radius or the bobbin diameter
calculated from the measured values in one or several of the previous run-out phases 30, the
(actual) course of the increase of the bobbin radius or the bobbin diameter can be precalculated
for the respectively following acceleration phase in the form of a time-varied compensatory
straight line 32. The difference between the (distorted) bobbin radius or diameter calculated
from the signals of the sensors 23,24 in the acceleration phases 31, and the precalculated course
of the increase of the bobbin diameter in accordance with the compensatory straight line 32 in the
acceleration phases 31 is a measurement of the slippage which actually occurred in the
acceleration phases 31. This slippage has been applied in Fig. 4 in percent over the time, scaled
to the diameter of the bobbin 17.
With conical cheeses the driven diameter in which the circumferential speeds of the friction
drum and the cheese coincide, changes fictitiously during acceleration, as can be seen in Fig. 5.
A fictitious diameter increase 40 takes place. Starting from this time 41, an exclusively slippage-
encumbered drive takes place. The bobbin diameter calculated during the acceleration phase
(diameter increase 40) is distorted, and during the phase 42 of the slippage-encumbered drive is
approximately constant. After switching off the friction drum, the titious diameter again
meets the bobbin at the point 43, and a real, driven diameter wanders, proportional to the sinking
rpm of the friction drum, on the bobbin from the large diameter in the direction toward the small
diameter. This is the so-called run-out phase 44. Towards the end of the run-out phase 44 the
driven diameter reaches a so-called neutral diameter zone based on the acceleration-free drive, in
which an achieved diameter of the conical cheese can respectively be calculated.
Reaching the neutral zone depends on several influence factors, for example on the flexing
work, the conicity of the bobbin, and the friction between the drum and the bobbin, which has a
disturbing effect on the diameter determination. The course of the curve shows a chronological
run-in or settling process. The settling process is not usable for determining the diameter of a
cheese, since here the distorted diameter does not coincide with the neutral bobbin diameter.
However, since it is already necessary to have an actual bobbin diameter available in a short time
for the next acceleration phase, this settling process must be equalized. This takes place by
inserting prior knowledge of the course of the run-in into the neutral zone. If it is assumed that
the above mentioned influence factors do not change during a disruption cycle, it must be
assumed that the previous disruption cycles have a similar course as the actual one. By means of
this knowledge it is possible to prepare a model course of the actual run-in behavior. Once this
model course has been found, it is possible to calculate a prediction of the neutral cone diameter
at any point in time of the run-in phase.
The calculation of a compensation polynomial of the nth degree offers itself as a model
process. Once the model parameters (polynomial coefficients) of the last n run-in cycles have
been calculated, it is possible, simultaneously with the actual run-in phase, to determine a
modeled run-in phase. To this end it is necessary to average the n sets of parameters of the run-
in cycles, and a simultaneous course must be produced. If the measured distorted diameter value
is divided by the corresponding model diameter value, an equalized diameter course is obtained.
This course is corrected by the amount of the actually valid cone diameter.
The integration of several run-in cycles into the model run-out is recommended, since it
must be assumed that by means of this occurring differences between different run-out cycles can
be averaged out. This method is represented in Fig. 6. Based on the run-outs (n - 2) and (n -1),
a model run-out is calculated for the run-out (n) and is simultaneously carried along. At the same
time the determined distorted diameter course ,s divided by the model diameter course, which
results in an equalized diameter course in the run-out phase.
The calculation of the time-variant compensatory straight line 32 and the slippage can take
place, for example, in accordance with an evaluation device explained in Fig. 2. The period
lengths measured by the sensors 23,24, and therefore also the angular speed of the bobbin, asp,
and of the friction drum, afw, are introduced into a quotient former 33. Since the radius rfw of the
friction drum 10 is constant, the quotient afw, to afw, is already representative of the bobbin radius
tsp so that a multiplication by the radius rfw of the friction drum 10 can be omitted. However, this
value cannot yet be used for a slippage determination, since it is a function of the diameter.
Therefore this value is entered into a linear filter 34, for example a Kalman filter, into which the
angular speed asp, of the bobbin 17 or 17 in Fig. 1, and the angular speed afw, of the friction drum
are also entered. The diameter values or, in the case of the conical cheese the calculated
equalized course, are only made available to the filter in the run-out phases of the pattern
disruption. This linear filter 34 constitutes the time-variant compensatory straight line 32. The
calculati a of the compensation radii takes place in the slippage-free phases. In the acceleration
phases the compensatory straight line is continued, based on its predetermined increase. This
compensatory straight line 32 is entered, together with the signal of the quotient former 33, into a
subtraction device 35, which then shows the slippage which is independent of the rpm and
independent of the diameter, i.e the sippage, which is independent of the state of the winding
The slippage s determined in this manner constitutes the basis which is independent of the
diameter for the calculation of the deposit shift. The following applies for the speed of the bobbin:
The difference distance on the bobbin surface generated by the sippage is calculated as E1
wherein t3 - t1, represents the length of time to be examined. In the case of discreted slippage and
speed courses, with -t as the scanning time, the following applies : E2
The value -1 is the deposit shift. To formulate from this a statement regarding the yarn deposit on
the bobbin surface can be done by using the length of a double lift on the bobbin surface as an
aid. This length is drum-specific and Is calculated as 1Trommet = 2xggx2xXx rTrommet, wherein gg
is the drum pitch number (number of drum revolutions for one deposit ift on the bobbin surface). If
the shift is related to a double lift, the relative shift in percent results E3:
Since no further manipution mechanisms are available for the shift formation, only the
acceleration of the friction drum can generate the sfppage required for pattern disruption and
therefore the shift. Based on the fact that the drive moment is always the same in every disruption
cycle independently of the motor operating point, the size of the shift during a bobbin travel also
provides information regarding the size of the actually present sippage.
If in the course of a bobbin travel after every disruption cycle, i.e the sequence of accelerations of
the bobbin and its non-driven run-out, the values for the slippage and the shift are entered as dots
in a diagram, tightly limited clouds of dots are created, whose position and orientation provide
Information regarding the quality of the respective disruption cycle, and thus of the slippage. A
representation of the state of the disruption cycles results. The cloud of dots also wanders with
the increasing diameter of the bobbin.
Since a waxed yarn has different frictional properties than an unwaxed yarn, the sippage
occurring In the course of winding these yarns Is different, and accordingly also the deposit shift.
This can be clearly seen in the slippage - deposit shift diagram represented in Fig. 7. A cloud of
dots recorded during a bobbin travel of an unwaxed yarn clearly differs in regard to its position,
extent and course from a cloud of dots which was recorded during the bobbin travel of a waxed
yarn. A prerequisite for this comparison is that, besides the preparation, the setting parameters
are the same during the two bobbin travels.
The absolute position of the cloud of dots can be compared over the entire machine or batch,
i.e. between many individual units. Because of this, deviations pointing to reduced or lacking
paraffin application can be detected even quicker and better.
Cylindrical bobbins of yarn of the same yarn count were wound at the same winding speeds.
An average contact pressure compensation was set and a yarn tensile strength of 30 cN
prevailed. The cloud of dots of the unwaxed yam extends in an area of little deposit shift and
slippage, approximately up to 3.5% relative deposit shift at 1.5% of slippage, while the cloud of
dots of the waxed yarn, clearly distinguished from the previous cloud, extends from
approximately 4% of relative deposit shift and 1.5% slippage up to 8% of relative deposit shift
and over 2.5% of slippage. A slippage-shift diagram makes it possible to clearly distinguish the
waxed and unwaxed state of a yam by the position of the slippage-shift points alone.
Slippage and frictional force also have a proportional connection. Therefore, a decrease of
the slippage can be detected over the course of the frictional force. The frictional force can be
calculated from the drive moment acting on the bobbin. During the acceleration phase of the
pattern disruption, the following drive moment acts on the bobbin:
This moment causes an rpm increase of the bobbin within a defined time interval. The
following applies here:/ E4 . In the area of the run-out phase of the drum and bobbin, the friction
moment mKeib = 0, and the bobbin rpm are reduced because of the loss and load moments acting
on the system. Since in this phase the system is without any further external influences, these
moments can be calculated by means of the courses of the angular speed. An uncoupling of the
moment determination between the rotating bodies of bobbin and drum is performed by means of
the calculation of the corresponding yields. Therefore the following applies to the loss and load
yield detected in the run-out of the pattern disruption:
While there is no possibility of measuring the loss yield of the drum-bobbin system with the
available measuring devices, the sum of the drive loss yield and the load yield as a result of the
yam tension force can be explicitly determined.
The determination of the fnctional and convection losses of the drum drive can be performed
with the aid of run-out curves. Since the winding speed, and therefore the angular speed of the
drum during the winding operation, vary only by the set pattern disruption lift (for example
between V 1.5% to V 6%), the determination of this loss yield is only meaningful in the
operational range. For this reason a model statement can be selected which takes into
consideration the run-out increase of the drum speed in the area of the production speed.
Therefore the following applies:
JTrommet is the dnim inertia.
The measurement of the increase of -aTrommet /-t can be performed during the normal
production operation without a noticeable production loss. Following each winding process
interruption, the drum drive needs to be uncoupled (lifting of the cheese) from the bobbin and
switched off for only a short time. After the initial increase has been measured, the drum
operation can be actively braked in order not to permit the creation of unnecessary production
losses. Since this loss moment is constant during a bobbin travel, it is only necessary to perform
the run- out measurements after each process-related interruption of the winding process.
The determination of the drive output is performed by means of the measured acceleration
moments of the drum and bobbin. Taking into consideration the equation
the result of the calculation of the total drive output during the acceleration-free phases
In order to be able to perform a more accurate localization of the characteristics of the climed
of points, and therefore of the process properties, it is possible to determine and process the
center and scattering of the cloud of points by means of this representation. The effect of the
paraffin application can be clearly seen in Fig. 8. Without having to perform a localization of the
cloud of points, it is possible by means of the rise of the cloud of points in the slippage-frichonal
force diagram alone to detect the quality of the paraffin application. With the unwaxed yan the
rise of the cloud of points is 4.2 N/%, that of the waxed yarn 0.63 N/%. The method in
accordance with the invention for monitoring the paraffin application can be considered to be
very dependable since the preparation of the yarn, i.e. the paraffin application, has a direct effect
on the friction number T of the friction drive.
If a yarn tensile strength sensor 13 is provided at the winding station, it can have a
connection with the evaluation device 25, so that the changes in yarn tensile strength can be
taken into account when determining the slippage. One of the most essential influence facters
which have no relation to the coefficient of friction of the cheese, is eliminated by means of the
1. Method for monitoring the application of paraffin to a traveling
yarn (15) at a winding station of a textile machine producing cross-
wound bobbins (17), at which textile machine the cross-wound
bobbin is driven at its periphery by a friction drum (10), the drive
of the friction drum being switched on and off at intervals to avoid
pattern windings in such a way that acceleration phases (31) with
slippage between the friction drum and bobbin and slippage-free
run-out phases (30) follow one another, characterized in that the
friction behaviour of the surface of the cross-wound bobbin (17) on
the friction drum (10) is monitored during bobbin travel, in that for
this purpose values proportional to the coefficient of friction are
determined and evaluated by continuous detection of the angular
velocities (Wsp, Wfw) of the friction drum and the cross-wound
bobbin, in that these values are compared with the expected course
over the bobbin travel and in that significant deviations from this
course are evaluated as a loss of the application of paraffin.
2. The method as claimed in claim 1, wherein the said winding station
is stopped when a loss of paraffin application has been detected, a
signal for the operator is additionally generated.
3. The method as claimed in one of claims 1 to 2, wherein the said
slippage between the cheese and the friction drum is determined
and evaluated as a value which is proportional to the coefficient of
4. The method as claimed in claim 3, wherein the said friction
drum transmits drive moment to the bobbin, said drive
moment determines the frictional force, which is detected as a
function of the slippage and used for evaluating the frictional
behavior of the surface of the cheese.
5. The method as claimed in claim 4, wherein during the
slippage-free run-out phase loss and load moments acting on
the drive system of the friction drum and the cheese are
measured and taken into consideration in the determination of
the frictional force.
6. The method as claimed in claim 4, wherein the said yarn
tensile force is measured, and the slippage value is corrected by
changes in the yarn tensile strength during the bobbin travel.
7. The method as claimed in claim 4, wherein the said frictional
behavior of the surface of the cheese on the friction drum is
evaluated by using the deposit shift, which corresponds to the
displacement of a reversing point of the yarn deposit on a
circumferential line on the bobbin in respect to the preceding
reversing point, is determined as a function of the slippage.
8. The method as claimed in one of claims 1 to 8, wherein the
said frictional behavior of the surface of the cheeses on the
friction drums of a predeterminable number of winding
stations of the bobbin winding machine is averaged and is
used as the basis for comparing the frictional behavior at. each
individual winding station.
In order to improve the running and sliding properties of the yarn during its further
processing, in particular for machine- knitting and knitting, it is waxed during rewinding in
bobbin winding machines by passing it along a paraffin body. When the paraffin body is used up
without this being noticed, the unwaxed yarn can cause yarn breaks or even needle breakages,
which leads to production errors or lost production. It is therefore proposed to monitor the
slippage at the winding stations where, to prevent pattern windings, the drive of the friction drum
is switched on and off at intervals in such a way, that acceleration phases with slippage between
the friction drum and the bobbin and slippage- free run-out phase follow each other. If the
slippage decreases in successive acceleration phases and remains at a low level, while the drive
output of the friction drum remains unchanged, this is considered to be an outage of the paraffin
|Indian Patent Application Number||2101/CAL/1998|
|PG Journal Number||20/2009|
|Date of Filing||30-Nov-1998|
|Name of Patentee||SCHLAFHORST AG & CO.|
|Applicant Address||POSTFACH 100435, D-41004 MONCHENGLADBACH|
|PCT International Classification Number||B65H 71/00|
|PCT International Application Number||N/A|
|PCT International Filing date|