Leesona Corporation

Lessona Corporation

Rene J Valois

Charles W Brouwer

Manuel G Teixeira

In a yarn storage feeder system of the type disclosed in U.S. Pat. No. 4,226,379 and having a yarn storage unit upon which a quantity of yarn is maintained from a yarn supply for intermittent withdrawal and delivery to yarn feeding and/or consuming means, such as a loom, and in which the yarn storage unit is driven by a low inductance DC motor such as a flat armature or pancake DC motor powered by a full wave rectified AC current, a significant improvement in motor operating efficiency, especially output torque, is achieved by incorporating an electrical choke in the circuit supplying such current to the DC motor. In the operation of the system the output speed of the motor is monitored and the current flow to the motor is controlled to maintain a preset reference speed by an SCR phase control unit, preferably through a transistor included in the motor circuit and having its base biased by the output of the SCR unit in synchronism with the frequency of the rectified AC current for a fraction of the duration of the current pulses, the extent of the fraction being adjusted to maintain the motor output speed at the reference level. The quantity of collected yarn can also be monitored and the speed control unit momentarily deactivated if that quantity exceeds a predetermined amount.

Yarn feeder motor control

A precise, accurate and sensitive control method and system for actuating the stop motion mechanism of a weaving loom equipped with a weft yarn storage feeder unit is disclosed. The storage and feeder unit includes a device for applying tension to the weft yarn being delivered from a weft yarn supply to the storage and feeder device. The tension device is equipped with a switch which provides a first electrical signal when the weft yarn being supplied to the storage and feeder device becomes slack or interrupted. That switch is connected with the weft yarn storage and feeder unit motor circuit. The weft yarn storage and feeder unit may be intermittently driven as the need occurs for feeding a weft yarn length or pick into the loom. The loom is stopped only in the presence of two concurrent signals, namely (1) a signal generated upon the detection of slack weft yarn or the absence of yarn in the tension device and (2) a simultaneous signal indicating operation of the motor to drive the weft yarn storage and feeder device. By the operation of the loom stop motion mechanism only in the presence of the aforementioned simultaneous signals, short picks, i.e., insertion of weft yarn lengths less than that required to extend from one side of the fabric being woven to the other, is precluded. Further, false signals which might arise from simple slackening of the yarn in the zone of the tension device are not operative to halt the loom.

Loom stop motion system and method

The disclosure relates to a system and method for correlating strand withdrawal speed from a strand supply package and utility means such as a shuttleless loom thereby reducing the possibility of supply package sloughs and strand breakage caused by conditions such as large changes in loading on an intermediate stationary drum type strand feeding and storage device. Thus, the loom operates to withdraw strand from the feeding device at a first average rate. A flyer withdraws strand from the supply package at a second rate which is slightly higher than the first average rate and wraps that strand onto the drum of the feeding device. Withdrawal of the strand by the flyer generates a balloon in the strand intermediate the strand supply and the flyer. Flyer drive speed is controlled by a feedback system which avoids changes in speed of the flyer except when occurrences of an overfill of strand on the drum occur. An overfill detector is provided for the drum and operates an on-off circuit in response to detection of an over-accumulation of strand on the drum to interrupt current flow to the flyer drive. When the overfill condition is relieved current is restored to the flyer drive. The frequency and duration of current interruptions is controlled so that the balloon of strand between the strand supply and the flyer is maintained at all times when the loom is operating. Consequently, strand sloughs and strand breakage which could result from frequent starts and stops of the feeding device are avoided. The system and method are equally applicable to strand feeding devices of the rotary drum type, in which case the motor is employed to control drum drive speed.

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Woonsocket, RI, United States of America

Rene J Valois