Based On The Research Of Closed Loop Control On High Speed Warp Knitting Machine Of Multi-speed Let-off System

When the warp knitting machine works normally, the function of the let-off system is to ensure the warp yarns can be unwound into the knitting mechanism precisely according to the needs of the organization. With the development of warp-knitting industry, electronic let-off system is increasing common in warp knitting. But it is a nonlinear system with time changing, which is not precise, and shows response lag and other issues in high or variable speed case. A kind of high speed warp knitting machine let-off system is put forward in the paper based on the closed-loop control and the transmission control system characteristic is tested and analyzed. The development of warp knitting of let-off system is introduced at home and abroad first, then the development bottleneck and existing problems of the current let-off system are emphatically expounded in the paper, a kind of high speed warp knitting machine let-off system is put forward. The components of the system and control principle are expounded. The difference and advantage of the open and closed loop are compared from the aspect of the control method. The rationality and feasibility of feedback roller in closed-loop control are represented by the use of the measurement of SCM01 four-channel vibration analyzer.It is studied about the control characteristics of multi-speed based on the closed-loop control of high-speed warp knitting let-off system. When the warp knitting machine operates normally, the multi-speed of beam motor occurs mainly in: 1. the speed of beam motor is varied along with the change of the run-in value between the sequences; 2. the speed of beam motor is changed following the change of the main spindle machine in the process of turning-on and turning-off machine. The SCM01 four-channel vibration analyzer is widely used in: 1. the speed curve of beam motor and real-time tension curve of warp with the change of the run-in value between the sequences; 2. the speed curve of main spindle, beam and real-time tension of warp tension in the process of turning-on and turning-off machine. It is expounded that the influence of switching time with the change of the run-in value, time of beam behind the spindle and the changes of warp tension on the control characteristics of multi-speed. Finally, a kind of warp compensation method is put forward through a study on capturing the motion characteristic of the beam motor lags behind the main spindle and changes of warp tension at the time of turning-on and turning-off machine. By modifying the parameters of the process ahead of the acceleration and deceleration of run-in value at variable-speed of spindle motor, the stability of the system is achieved.In a word, a high-speed warp-knitting electronic let-off system is designed and developed based on closed-loop control in this paper, and the multi-speed control characteristic of the system is tested and analyzed, then a kind of warp compensation method is proposed. It is proved that the system has the advantages of high let-off accuracy and good response performance, which greatly improves the beam problem caused by warp knitting machine stopping. The quality of warp knitting products is improved, and it has great significance on improving the technological level of Chinese warp.