Winding – tensioning – or guiding – Helical or random winding of material – Joining ends of material
Reexamination Certificate
2002-04-15
2004-03-09
Jillions, John M. (Department: 3654)
Winding, tensioning, or guiding
Helical or random winding of material
Joining ends of material
C242S485200, C242S485500
Reexamination Certificate
active
06702223
ABSTRACT:
CROSS-REFERENCES TO RELATED APPLICATIONS
This application claims the benefit of German Patent Application 10118659.2 filed Apr. 14, 2001, herein incorporated by reference.
BACKGROUND OF THE INVENTION
The present invention relates to a winding head of a textile machine.
It is known that considerable reductions of costs are possible, for example in preparation for fabric weaving, if the preset lengths of the yarn wound on the cheeses can be maintained as accurately as possible. This applies in particular when cheeses are placed together on a bank creel to be drawn off and warped or beamed. The greater the deviations in yarn length from one cheese to another, the greater the differences between the residual amounts of yarn left on the cheeses at the completion of the warp or beam. With high-quality yarn material, this problem leads to intolerable losses because of considerable amounts of wasted yarn, or to the necessity for elaborate and time-consuming re-winding of the residual yarn. In cheese-producing textile machines, it is customary to derive the length of yarn wound onto each cheese from the revolutions of the cheese or the revolutions of the drive roller for the cheeses during winding of the cheeses. Considerable inaccuracies in detecting the yarn length, or the yarn speed, can occur because of factors such as slippage or traversing motions.
Devices and methods are used for preventing such inaccuracies, by means of which the traveling yarn can be measured in a contactless manner, and signals which are proportional to the yarn speed can be generated. The speed which has been determined by means of a running time correlator, for example, can be evaluated for the determination of the length of the running time of a textile yarn.
For example, Swiss Patent Publication CH 669 777 A5 describes a method and a device for the contactless length measurement of a yarn wherein, by means of an optical correlation system having a screen and at least one photoelectrical detector, a yarn section is illuminated whose image is converted into an electrical push-pull signal containing a frequency proportional to the speed wherein, after separating push-pull portions and interference signals, the period length of the signal is respectively measured at least once during a scanning interval of a constant length of time if the signal exceeds a minimum amplitude value, and the length is determined from the individual measured length values, which were determined by forming the reciprocal value. A signal proportional to the yarn speed is generated in a contactless manner by the reproduction of a yarn section on a screen and photoelectrical conversion. The signal is scanned at fixed scanning intervals and the partial yarn length for each scanning interval is determined. The yarn length results from the addition of the partial lengths.
The method disclosed in German Patent Publication DE 43 27 587 A1 operates with a running time correlator. Here, the speed of the running yarn is measured at least at one reference winding location, a mean value is formed from this measurement and this mean value is used as the basis of the preset value of the winding speed at the remaining winding heads. By means of the direct detection of the winding speed at the running yarn, it is intended for the determination of the production output to reduce or eliminate the effects of interference factors, which heretofore have negatively affected the accuracy of the determination of the production output. The employment of such a measuring device for determining the winding speed of the running yarn only at one or a few winding heads of a cheese-producing textile machine is intended to provide a considerable savings in comparison to the arrangement of such measuring devices at all winding heads. However, using a few reference winding heads, or even only a single reference winding head out of a plurality of windings heads of the winding frame, it is not possible to assure that every cheese finished on this winding frame has a yarn length which matches with a sufficient accuracy the preset yarn length for use in the weaving preparation. The deviations from length between the detected, or determined produced amounts of yarn, which still occur even at reference winding heads, and the actual length of yarn wound on the cheese, are marginal in comparison to the production output and can therefore be easily neglected in the course of the determination of the production output of the entire winding frame. However, these deviations in length are no longer tolerable for the precise maintenance of a preset yarn length. Thus, a winding frame designed in accordance with German Patent Publication DE 43 27 587 A1 does not meet the greater demands made for agreement of the preset yarn length with the yarn length which is actually wound on the respective cheese.
As described in German Patent Publication DE 42 25 842 A1, European Patent Disclosure EP 0 000 721 A1 proposed to determine the yarn speed via two sensors disposed at a fixed distance from one another and operating in a contactless fashion. Sensors that operate optically or capacitatively, for instance, can be considered for this. These sensors detect stochastic yarn signals in the form of analog noise signals that result from irregularities in the yarn surface or yarn mass in the longitudinal direction of the yarn. The stochastic signal determined upstream in the yarn running direction is shifted temporally until it bears maximum similarity to the stochastic signal detected by the sensor disposed downstream. The thus-determined delay of the first signal corresponds to the time span required by the yarn to travel from the first to the second sensor. Because the spacing of the two sensors is known, the yarn speed can easily be determined in this manner. Typically, the mathematical operations typically characterized as cross-correlation methods are employed to achieve this; however, these calculations are time-consuming. The delay is not problematic when the yarn experiences no or only very little acceleration. However, rapid changes in speed, such as occur in the winding process after yarn breakage or bobbin changing, for instance, can not be controlled well enough in this manner to allow for precise measurement.
German Patent Publication DE 42 25 842 A1 incorporates and improves upon the running time correlator of European Patent Disclosure EP 0 000 721 A1. German Patent Publication DE 42 25 842 A1 shows a device for measuring the speed of textile yarns on a winding apparatus. The winding apparatus is used for producing cheeses, wherein the rotation of the cheese is created by means of the frictional effect from a drive roller. A running time correlator circuit such as the one described above with two measuring points, which are arranged at a fixed distance in the movement direction of the running textile yarn and where a contactless measurement is performed, and a further signal transmitter are connected with each other. The signal transmitter detects the rotary movement of the drive roller and emits signals which are proportional to the yarn speed. These signals are supplied to the running time correlator for presetting the range for latching of the control circuit to the correct maximum idle time (i.e., maximum of the correlation function for the running time of the yarn from the first to the second measuring point constitutes the idle time). As a result, it is possible to utilize the high degree of measuring accuracy of the running time correlator without a considerable outlay in computing capacity even at changing yarn speeds. The speed determined by means of the running time correlator can be directly evaluated via an integrator for the accumulated running time length determination of a textile yarn.
The publications cited above describe possibilities for precisely determining the yarn speed. However, the agreement of the yarn length wound on the cheese with the preset yarn length, as well as in a comparison of the cheeses with each other, still is insufficient for the greatest
Krüger Andreas
Sturm Christian
Jillions John M.
Kennedy Covington Lobdell & Hickman LLP
W. Schlafhorst AG & Co.
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