W. Schlafhorst Ag & Company

Urs Meyer

Ferdinand Hermanns

Ferdinand-Josef Hermanns

Andreas Kruger

Random wound yarn packages are produced at a winding station of a winding machine having a friction roller for driving the yarn package being wound by: winding yarn onto an initially empty bobbin core with the friction roller to form a finished random wound yarn package; and, during the winding, continuously (i) detecting with sensors a value representative of the angular velocity of the yarn package and a value representative of the angular velocity of the friction roller, and (ii) calculating a value representative of yarn application of the yarn package being wound, which is indicative of yarn package quality, based on the detected values. The yarn application value can be calculated based on a number of revolutions of the yarn package or based on a winding time of the winding process, and the yarn application values can be recorded as a function of time for later reference or display. Calculation of the diameter of the yarn package being wound is also provided, and yarn application values can be recorded as a function of the diameter. When the calculated diameter at least equals a threshold value, the winding process is stopped. Moreover, yarn application values are compared to set values and parameters of the winding process are adjusted if a deviation results, especially during patter winding zones.

Method and apparatus for monitoring winding density in producing random-wound yarn packages

In order to improve the traveling and sliding properties of a yarn during its further processing, in particular for knitting, it is waxed during rewinding in cheese winding machines by passing it along a paraffin body. When the paraffin body is used up, the unwaxed yarn can cause yarn breaks or even needle breakages, which leads to production errors or lost production. At the winding stations, the drive of the friction drum is switched on and off at intervals to cause alternating acceleration phases with slippage between the friction drum and the bobbin and intervening slippage- free run-out phases to prevent pattern windings. The slippage is monitored over the course of the winding operation. 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 interpreted to indicate an outage of the paraffin application.

Method for monitoring the application of paraffin on a traveling yarn

A method of producing a random wound yarn package includes driving a yarn package with a friction roller, setting and maintaining a constant yarn tension in the yarn, setting and maintaining a constant contact force between the friction roller and the yarn package being driven thereby, and temporarily regulating the yarn tension and the contact force during a time of a pattern winding zone of the winding process in order to maintain a constant winding density both before and during the time of the pattern winding zone. The winding station includes a friction roller for driving the yarn package, a yarn tensioner, a device that generates a constant contact force between the yarn package and the friction roller, and an evaluation and regulation unit that temporarily regulates the yarn tension generated by the yarn tensioner and the contact force generated by the device during the time of the pattern winding zone. A program of the evaluation and regulation unit regulates the yarn tension and the contact force by predetermined amounts and at predetermined times. Alternatively, yarn application representative of winding density is calculated based upon circumferential velocity, angular velocity, period, and/or frequency of the yarn package and friction roller continuously detected by sensors, and the yarn tension and contact force are regulated when the calculated yarn application deviates from a set value.

Method and apparatus for maintaining constant winding density in the

A yarn package (both conical and cylindrical) is produced at a winding station of a textile winding machine by alternately: accelerating the friction roller driving the yarn package with slippage between the friction roller and the entire surface of the yarn package; and decelerating the friction roller driving the yarn package without slippage between the friction roller and at least part of the surface of the yarn package, e.g., the neutral zone of a conical package. The periods (and thus the frequencies and angular velocities) of the friction roller and the yarn package are detected by sensors which communicate the detected values to a control and evaluation device. Based on the detected values during at least one phase of deceleration, the control and evaluation device estimates the yarn package radius during an acceleration phase. Additionally, based on detected values during the acceleration phase, and based on the known radius of the friction roller, the control and evaluation device calculates a distorted radius of the yarn package and compares the estimated radius with the distorted radius to determine a value of slippage that occurs during the acceleration phase. The winding process is then adjusted if standard values of slippage indicative of a quality yarn package are not achieved.

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Zurich, Switzerland

Urs Meyer