Abstract:In view of the fact that the yarn conveying state monitoring is not timely in the knitting process of the existing knitting circular weft knitting machine, particularly, the current rate of diagnosis of common faults such as the low yam breakage and yarn running, the method of monitoring the yarn feeding of the circular knitting machine is analyzed in this paper, and combined with the needs of process control, an external monitoring scheme of yarn based on infrared sensitization principle is proposed. Based on the theory of photoelectric signal processing technology, the overall framework of yarn motion monitoring is designed, and key hardware circuits and software algorithms are designed. Through the experimental tests and the on-machine debugging, the scheme can timely monitor the yarn movement characteristics during the knitting process of circular weft knitting machines, and improve the correct rate of common fault diagnosis such as yarn breakage and yarn running of the circular weft knitting machine, which can also promote the yarn dynamic detection technology in the knitting process of circular welt knitting machines made in China.
Key words:Circular Weft Knitting Machine; Yam Conveying State; Monitoring; Photoelectric Signal Processing Technology; External Hanging Yarn Monitoring Scheme; Yarn Motion Monitoring.
In recent years, the development of high-speed, mechanical sensors, piezoelectric sensors, capacitive sensors, and efficient yarn breakage by changing the signal level in knitting circular knitting machines has led to the development of accurate sensors, fluid sensors, and photoelectric sensors for yarn motion status diagnosis. Piezoelectric sensors make it crucial to monitor yarn movement1-2). Electro-mechanical sensors detect yarn breakage based on the dynamic characteristics of the signal during operation, but with yarn breakage and yarn movement, which refer to the yarn in the knitting state with rods and pins that can swing or rotate, respectively. In case of yarn breakage, the above mentioned mechanical measurements have to contact the yarn, which increases the additional tension.
Currently, the yarn status is mainly determined by the swinging or rotation of the electronic parts, which triggers the yarn break alarm and affects the product quality, and these sensors are generally unable to determine the yarn movement. Capacitive sensors can determine yarn fault by capturing the charge effect of electrostatic charge in the internal capacitive field during yarn transport, and fluid sensors can determine yarn fault by detecting the change of fluid flow caused by yarn breakage, but capacitive and fluid sensors are more sensitive to the external environment and cannot adapt to the complex working conditions of circular weft machines.
Image detection sensor can analyze yarn movement image to determine yarn fault, but the price is expensive, and a knitting weft machine often needs to be equipped with dozens or hundreds of image detection sensors to achieve normal production, so the image detection sensor in the knitting weft machine can not be used in large quantities.
Post time: May-22-2023