Abstract:

Objective When the electronic shogging system of a warp knitting machine is in operation, it needs a certain period to process and transmit the shogging control signal, resulting in the lag of the shogging of the guide bar, which makes the shogging and the swing of the guide bar not synchronized, affecting the high-speed operation of the warp knitting machine. If the shogging lag of the guide bar can be dynamically compensated, the lag of the electronic shogging system could be improved or even eliminated, thus improving the overall performance of the electronic shogging control high-speed warp knitting machine.

Method The shogging command signal received by the servo driver and the actual running signal of the servo motor in the electronic shogging system were collected in real time by the monitoring software. Three types of AC servo systems commonly used in the electronic shogging system of the warp knitting machine, such as Yaskawa, Tamagawa and Inovance, at different speeds of 700 r/min, 1 100 r/min, 1 500 r/min and 1 900 r/min were involved in the research. The lag between the shogging command curve and the actual motion curve of the systems above was evaluatedin to understand the effect of different running speed of warp knitting machines.

Results Through testing the shogging command curve and the actual motion curve of the electronic shogging system using three kinds of AC servo systems at different speeds of 700 r/min, 1 100 r/min, 1 500 r/min and 1 900 r/min of warp knitting machines, it was found that the actual motion curve of the servo motor lagged behind the command curve of the servo driver in the electronic shogging systems with all three different shogging servo systems. The lag time of the electronic shogging system of the same servo system did not change with the running speed of warp knitting machine, that is, the lag time of the system was constant when the configuration of the electronic shogging system are fixed. The lag time of the electronic shogging servo system with different servo systems was found different, which was related to the performance and internal parameter setting of the shogging servo system itself. On this basis, the shogging lag was pre-compensated by modifying the corresponding control program in the electronic shogging system. During the operation of the warp knitting machines, the running speed of the machine main shaft was detected in real time, and the current shogging angle compensation value caused by the lag was calculated, which was then used for the shogging command control of the next knitting cycle. Through the test of the command curve of the shogging servo driver and the actual motion curve of the servo motor under the conditions of no compensation and compensation, the following synchronization of the actual motion curve of the servo motor and the command curve of the servo driver after compensation was improved, and the running speed of the warp knitting machine of the electronic shogging system was improved, from the original 1 780 r/min to more than 2 100 r/min, and the running performance and working efficiency of the high-speed warp knitting machine were improved effectively.

Conclusion The shogging data in the electronic shogging system of the warp knitting machine needs to be calculated and transmitted, and the motion response of the servo system is delayed, which makes the actual motion of the shogging servo motor lag. When the system configuration is fixed, the shogging lag time is constant regardless of the running speed of warp knitting machine. The actual shogging lag of the guide bar of the electronic shogging system of the warp knitting machine affect the synchronization between the swing and the shogging of the guide bar, especially with the improvement of the running speed of the machine, making the warp knitting machine unable to run well. By presetting a forward of the guide-bar shogging angle, the lag compensation of the electronic shogging system has been achieved, and the running characteristics of the electronic shogging system of the warp knitting machine are effectively improved. The practice shows that the running speed of the warp knitting machine can be increased by 18%, which greatly improves the running speed of high-speed warp knitting machine with electronic shogging system.

Key words: warp knitting machine, electronic shogging system, running speed, servo control, response characteristic