Research On Let-off And Broken Warp Detection Systems Of Computer Sewing Machines

Nowadays, self-adhesive spandex elastic cloth produced by computer sewing machines in the textile industry has been obtaining great market prospects. Featured by strong stability, high revolving speed and high degree of automation, Computer sewing machines that are functioning as the key production equipment are thus of great significance in improving production efficiency. However in the production processes, stitch-bonding companies remain confronted with the dilemma that stability of warp tension cannot be ensured during Let-off, and the wastes of materials remain a major problem since computer sewing machines fail to stop in time on the sudden warp broken. Aiming at the above problems,this paper focuses on researches of let-off and broken warp detection systems which are centered on 21 MA controller through secondary developments of computer sewing machines.Detailed researches are as follows:(1) This paper describes the remaining problems during stitch-bonding process, which are based on the needed functions of let-off and broken warp detection system, and designs an overall plan and tests the spandex warp stability.(2) Based on the operating principles of tension sensors, this paper designs tension sensors with bi-hole paralleled beams.(3) Based on the mechanical structures of warp beams, the driving motor model is pinpointed. Then by the analysis of tension control,the fuzzy control method is come up with. Afterwards PLC control program and HMI have been developed which are based on tension control principles. 21 MA controller and the main control system, communication circuits and programs for servo drive are researched and developed completely.(4) By analyzing the deffects of broken warp in order to cope with the situation that current detection system fails to meet the needs, mechanical structures and controlling systems are redesigned, which have been proved by practical uses to be capable of meeting the production requirement.This system is able to deliver real-time monitoring of spandex warp tension and to control revolving speeds that are based on the real-time warp tension to meet the elastic ratio. In addition, it can detect the broken warp signal in time to improve automation of computer sewing machines and to promote production efficiency by reducing wastes on nonwoven and spandex filaments.