Calculation and Analysis of Horizontal and Vertical Lapping Angles in Tricot Warp Knitting

Abstract

The lapping angle, which affects the style and quality of production, has been studied as a parameter of weft knitting. But the importance of the lapping angle has not been considered during the warp-knitting cycle. This paper shows that the lapping angle exists in the process of warp knitting and can be divided into horizontal and vertical lapping angles. Models for the lapping angles of closed and open loops were devised, and the lapping angles (horizontal and vertical lapping angles) of closed and open loops were calculated and analyzed. Furthermore, the paper seeks to investigate the factors that influence the lapping angle of tricot warp-knitted fabrics and summarize the rules. Moreover, the vertical lapping angle can affect the loop coverage. Results reveal that the decrease in number of underlaps and an increase in take-off density enables loops of the front guide bar to show on the face of the fabric. Moreover, it is also advantageous for an apparent front loop visibility when the front guide bar knits in open loop.

Numerical simulation and tension regulation of yarn mechanics on warp knitting machines

“…The dynamic tension of the yarn is generated by the motion of the loop-forming mechanism. By analyzing the movement of the loop-forming mechanism, the dynamic equation of the yarn required for a course can be obtained: ðl r ; hÞ ¼ ðDl fb ; hÞ þ ðDl ou ; hÞ þ ðDl lh ; hÞ þ ðDl sk ; hÞ (1) where h is a certain angle of a course, h falling in (0 , 360 ), l r is the amount of yarn required at h, Dl fb is the amount of yarn required at h when the bar swings back and forth. Dl ou is the amount of yarn required at h for lapping, Dl lh is the amount of yarn required for the knitting needle to move up and down at h, and Dl sk is the amount of yarn required for the sinker to swing back and forth at h.…”

“…According to the dynamic model, the dynamic yarn demand in a course is determined by the motion of the loop-forming mechanism. When the number of the lapping is determined, the dynamic yarn demand in a course can also be determined according to equation (1). Simultaneously, the set yarn supply amount is unchanged.…”

“…Due to the special knitting method, warp knitting achieves efficient production. 1,2 At the same time, warp knitting is a complex coordination movement with multiple structures, which has high technical requirements for mechanical and control performance. For example, the loop-forming movement includes complex high-speed coordination movements such as needle up and down motion, guide bar back and forth swing, guide bar lapping motion and sinker back and forth motion.…”