Patent EA-000316-B1 (EA)
Title: Thread feed device for elastic yarn
Inventor: SCHMODDE HERMANN
IPC: D04B15/50
Filed: 1996-09-17
Abstract: 1. Thread feed device for elastic yarn to feed yarn to loop-forming places in which the thread consumption fluctuates markedly with time for raschel and knitting machines, in particular for flat-knitting machines (4) comprising - a thread-feed device to define the thread path, determined by thread-guiding elements, - a thread-feeding wheel arranged on the thread path so as said wheel can be defined by a thread and which serves for conveying the yarn in predetermined regimes, - an electrical motor, having a low inertia, rigidly-connected to the thread-feeding wheel, a tension sensor for monitoring of the thread tension and said sensor has a thread-guiding element which enables at least a slight deviation along the measurement path, - a regulator via the motor, driving the thread-feeding wheel is monitored by signals, transmitted by the sensor device so as the thread tension is regulated with setting to the nominal value, - a thread store for intermediate thread storing and, if necessary, for repeated take-up, fed by the thread-feeding wheel and not consumed in the loop-forming places, and for feeding the thread, needed in the loop-forming places, but which was not fed by the thread-feeding wheel; characterized in that the thread store (19) is functionally separated from the sensor (22) device, and all thread path is not tensed, the tension sensor (22), having the measurement path substantially equal to zero, and the thread store (19) takes the form of a substantially straight section between the thread-feeding wheel (11) and the loop-forming place, on which the elastic yarn (2) enables to free tension, and the thread, stored in the thread store has a rigidity coefficient, which is less than the predetermined given value, equal to the ratio of maximum change of strength to the length of thread, which can maximum store the thread store. 2. Use of the thread path of the thread feed device for elastic yarn provided for the thread feed to the loop-forming places with the thread consumption fluctuating markedly with time in raschel and knitting machines, in particular for flat-knitting machines (4) comprising - a thread-feed device to define the thread path, determined by thread-guiding elements, - a thread-feeding wheel arranged on the thread path so as said wheel can be defined by a thread and which serves for conveying the yarn in predetermined regimes, - an electrical motor, having a low inertia, rigidly-connected to the thread-feeding wheel, - a tension sensor for monitoring of the thread tension and said sensor has a thread-guiding element which enables at least a slight deviation along the measurement path, - a regulator via the motor, driving the thread-feeding wheel is monitored by signals, transmitted by the sensor device so as the thread tension is regulated with setting to the nominal value, as the thread store for receiving, intermediate storing and feeding of the thread, which, with marked fluctuations of the thread tension due to inertia moments of the thread-feeding wheel and the motor is fed excessively or insufficiently, compared to the thread consumption in the knitting machine., - a straight section is formed between the thread-feeding wheel (11) and the loop-forming place, on which the elastic yarn (2) enables to free tension, and the thread, stored in the thread store has a rigidity coefficient, which is less than the predetermined given value, equal to the ratio of maximum change of strength to the length of thread, which can maximum store the thread store. 3. Thread feed device of Claim 1, characterized in that the tension sensor (22) is provided with a mobile element (25), having the maximum measurement path, which, at least, by one order less, than the thread length (2) to be intermediately stored 4. Thread feed device of Claim 1, characterized in that the tension sensor (22) is provided with a spring catch (51), curvature of which is determined by the thread tension and which connected with a converter for measuring the curvature. 5. Thread feed device of Claim 5, characterized in that the converter is an electromechanical converter with a small required deviation. 6. Thread feed device of Claim 1, characterized in that the tension sensor (22) is constructed separately from the rest of feed device. 7. Thread feed device of Claim 1, characterized in that the tension sensor (22) has a separate suspension made so to eliminate coupling with the vibrating movement of the knitting machine. 8. Thread feed device of Claim 1, characterized in that it is protected from the vibrating movement of the knitting machine. 9. Thread feed device of Claim 1, characterized in that it is provided with the regulator (24) to monitor the driving means in all regimes of operation, independently of knitting machine (4) speed, based on the thread tension, determined by the tension sensor. 10. Thread feed device of Claim 9, characterized in that the tension regulator (24) is a proportional-integral regulator. 11. Thread feed device of Claim 9, characterized in that the tension regulator (24) is a proportional-integral-differential regulator. 12. Thread feed device of Claim 1, characterized in that the driving means (9) is a step engine. 13. Thread feed device of Claim 1, characterized in that the driving means (9) is an electrical motor with a disc rotor. 14. Thread feed device of Claim 1, characterized in that the driving means (9) and corresponding control means (tension regulator 24) are made providing the operation of the driving means (9) un two directions of rotation. 15. Thread feed device of Claim 1, characterized in that the thread-feeding wheel is formed by radially-arranged wire clamps (13) are fastened on the hub (12) each said clamp has a section (16), passing essentially in axial direction for winding the thread, wherein each wire clamp (13) has two spokes (14, 15), on which the axial section (16) rests. 16. Thread feed device of Claim 1, characterized in that the thread path from the thread-feeding wheel (11) to the guide machine element (6) of the knitting machine (4) passes essentially in one direction. 17. Thread feed device of Claim 1, characterized in that for determining the present value of the thread tension two independently-operated tension sensors (22, 22) are provided and situated at a certain distance from each other along the thread path. 18. Thread feed device of Claim 1, characterized in that a filter (29) is arranged between the tension sensor (22) and connected with it the tension regulator (24) 19. Thread feed device of Claim 1, characterized in that the filter (29) suppresses frequency interference. 20. Thread feed device of Claim 1, characterized in that the filter (29) is provided with compensating means to suppress interference signals. 21. Use of the thread feed device according to one or several preceding Claims for flat-knitting machine.