Research Of Constant Tension Yarn Feeder For Knitting Machine

Yarn feeder is an important part of textile equipments, its basic function is feeding yarn for knitting machine such as circular machine, seamless machine, hosiery machine, flat machine and warp machine. In the textile industry, problem of yarn tension control has always been attentions and difficulties that lots of people focus on. Whether the yarn tension controlled stably directly affects the efficiency of textile industry and the quality of textile production, which requires the yarn feeder to deliver the yarn tension constantly while completing its basic function of feeding yarn. Based on the above background, in this paper, a constant tension yarn feeder for knitting machine is researched and developed.Firstly, through the analysis on existing tension control technology domestic and abroad, this paper presents a scheme of which takes resistance strain sensor as the core detection element of tension detection module, takes brushless DC motor as the actuator of tension adjustment module, takes STM32 microcontroller as the main controller of tension control module.Secondly, after the tension control system and strategy were analyzed, a fuzzy PID controller is designed. Through a comparative analysis by Matlab/Simulink simulation of fuzzy PID controller and the conventional PID controller, it is concluded that for yarn tension control system, fuzzy PID controller is of better performance.Thirdly, the hardware and software of the constant tension yarn feeder is designed, the hardware mainly includes brushless DC drive circuit, tension signal conditioning circuits and STM32 microcontroller and peripheral circuits, the software mainly includes the control and speed test of feeding motor, the sampling and filtering of tension signal and the implementation of fuzzy PID control algorithm. Tension control System sample the tension signal in real time and compare the sampled signal with the target signal to get the deviation and deviation rate, delivers it into tension control algorithm and output a control value to adjust the speed of yarn feeding motor, so as to realize the real-time control of the yarn tension.Finally, the constant tension yarn feeder is researched and analyzed by experiment,the experiment includes a calibration of the tension detection module, a test of the yarn feeding speed and a test of tension control performance. Through the analysis of the experimental, it is included: it is of good linearity for tension and voltage output of the tension detection module, the maximum feeding speed is up to 800m/min, the tension control ranges between 5c N to 100 c N and the tension control is of good performance.