Control of the stability circular knitting process with passive yarn feeding

Abstract

During the knitting process it is important to cont-rol and detect defects and quickly remove them. Existent optical and mechanical devices react to broken threads, hook, butt, latch of needles, holes of fabrics, but they do not give any information about knitting process.For this aim the method of measuring threads ten-sion during knitting was proposed. When the needle hook, heel, latch are broken, the yarn tension decreases. This reaction depends on yarn feeding method, static thread tension, knitting speed, linear density and mechanical characteristics of threads.In this paper, the research of needle defects during knitting with passive yarns input was made and it was de-termined, that the biggest influence on reducing threads tension to defect had input tension. The influence of knit-ting speed and linear density was small. Reducing yarn tension in percentage of average maximum tension showed, that the decrease of yarn tension is higher when the speed of knitting and tension is smaller for the investi-gated polyester, polyamide and cotton threads. Decrease of tension for cotton thread in all cases was less than for other investigated threads.The results of experiments for the determination of dynamic rigidity modulus and dynamic viscosity modulus show, that both values of modulus for cotton yarns were lower than polyester threads, when the threads tension was 10 cN and were similar at tension values from 20 cN till 30 cN.That enabled to explain, why the Cotton yarn have least reaction to the needle defect, when the yarn in-put tension during knitting was small.