Patent GB-1324422-A (GB)
Title: Yarn winding
IPC: D01H1/30
Filed: 1970-11-04
Abstract: 1324422 Controlling spindle speed; slow down period of winding cycle FIBER INDUSTRIES Inc 4 Nov 1970 [7 Nov 1969] 52354/70 Heading D1D A method of winding a yarn package on yarn over-end winding apparatus in a manner to reduce slow down breakages and loops while leaving the yarn strung for start-up, comprises positively forwarding yarn by draw rolls, i.e. rolls engaging yarn immediately before it is taken up on a package, to a rotating spindle, and programming the slow down period of the winding cycle by positively controlling the spindle speed in a predetermined relationship to the speed of the draw rolls during the first part of the period until the draw rolls reach a predetermined low speed, applying maximum spindle brake at a predetermined time after said low speed is reached, stopping the draw rolls independently of the spindle, and thereafter bringing the spindle to rest after the draw rolls become stationary. During the normal running of the apparatus i.e. during package wind, the apparatus is controlled as shown in Fig. 3. A D.C. motor is provided to drive the spindle, the speed of rotation of which is converted to volts in a first tacho-generator. The draw rolls are driven independently of the spindle by an A.C. motor and the speed of the draw rolls is converted to volts by a second tacho-generator. A servo control device comprising a magnetic amplifier is provided to control the speed of the motor driving the spindle. The cam controlling the package build is mounted on a shaft rotating at constant speed and the cam follower comprises the slider of a linear potentiometer, the output of which comprises a reference signal which is fed to a reference error unit. The reference error unit compares the reference signal with the signal from the spindle tachogenerator and the error signal is fed to the servo device to control the current fed to the motor driving the spindle. At a predetermined point in the winding cycle the programme cam operates a stop button to de-energise the A.C. motor driving the draw rolls, see Fig. 4. At the same time, the reference signal potentiometer is disconnected and the signal from the draw rolls tacho-generator is fed to the reference error unit. The draw rolls slow down normally and the signal from the spindle tacho-generator is compared with the draw-roll tacho-generator signal and the error signal fed to the servo device whereby the spindle slows in relationship to the slowing of the draw-rolls. The spindles may be partially braked at this stage. The signal from the draw-rolls tacho-generator is also fed to a speed sensing device and when a predetermined low speed is sensed, a time delay is operated whereby the full spindle brake is applied at a predtermined time after the low speed is sensed. Simultaneously with the application of full spindle brake, the low speed sensing device sends a signal to deenergise the D.C. motor driving the spindle whereby the spindle comes to rest after the draw rolls have become stationary.  Means may be provided to prevent 'hunting' of the spindle drive motor during the first part of the slow down period. At the start of the slow down period a brake may be applied to the draw rolls as the A.C. motor driving the draw rolls is de-energised. The start-up period of the package winding cycle may also be programmed such that the draw-rolls are not connected to the A.C. drive motor until the spindle has been connected to the D.C. drive motor. The ring rail in a ring-and-traveller winding apparatus may be controlled during the slowdown period such that the rail comes to rest after the draw-rolls have stopped.