Heald frame motion trajectory based on minimum warp friction in the shedding process of three-dimensional woven fabrics

Abstract

The partial fiber breaking in the warp yarn of three-dimensional (3D) woven fabrics needs to be urgently reduced considering the large shedding displacement and repeated yarn frictions in the fabricating process. A kinematical model of the heald frame was established in order to analyze the impact and wear of the warp yarn in the shedding process of 3D weaving. The variation tendency of the friction force between the yarn and heddle eye was obtained and the variable acceleration trajectory of the heald frame based on minimizing the friction and impact load on the yarn was derived. The experimental results showed that the fiber breakage rate in one warp yarn using the derived curve trajectory reduced drastically. The research results are beneficial to the theoretical design of the shedding system of weaving machines for 3D woven fabric.

Study on the wear characteristics of carbon fiber yarns under the influence of multifactor coupling on braiding carriers

“…The elasticity coefficient of the spring in the tension‐adjusting mechanism mainly determines the lower limit value of the sudden change in yarn tension during the unwinding process. When the braiding carrier unwinds the yarn, the carbon yarn is subjected to a large rigid impact, which increases the wear between the unwinding yarn and the yarn on the bobbin 33,34,45 . As shown in Figures 5C–F,H and 6F, it is known that yarn tension increases with increasing speed and the degree of wear of the carbon fiber yarns also increases with the increase in unwinding speed.…”

“…When the braiding carrier unwinds the yarn, the carbon yarn is subjected to a large rigid impact, which increases the wear between the unwinding yarn and the yarn on the bobbin. 33,34,45 As shown in Figures 5C-F,H and 6F, it is known that yarn tension increases with increasing speed and the degree of wear of the carbon fiber yarns also increases with the increase in unwinding speed. When the motor rotation speed was varied from 120 to 150 rpm, the extreme difference in the hairiness gray values of carbon fiber after the experiments with I-III braiding carriers increased by 30%, 24%, and 37%, respectively.…”

“…Carbon yarn breakage is a combined effect of external forces, which is affected by a combination of friction, bending, deflection, tension, and material fatigue. 14,45,46 A braiding carrier with a yarn bobbin installed vertically, the carbon yarn first undergoes a 90 bending along the axis of the yarn bobbin, then undergoes a 90 twisting upon contact with the guiding element. From the first guiding element to the second guiding element, a 90 twist occurs then a 180 bend occurs around the second guiding element.…”

A yarn hanging model for estimating the applied initial warp tension in the multi-layer weaving process

“…However, the partial fiber will break due to the large shedding displacement and repeated yarn friction in the fabricating process when the applied yarn is too large. 8 The yarn hanging model could estimate the applied yarn tension based on the weaving conditions and the path of yarn hanging required for clear shedding. The yarn tension estimated by the model can ensure that the shedding is clear and reduce yarn wear as much as possible, as the tension is the minimum necessary for a clear shedding.…”

“…Due to repeated friction of the warp yarns with the heald frame in the 3D woven fabric weaving process, the excessive initial warp tension applied will increase the friction between the warp yarns and the heald frame, which further increases yarn wear. 7,8 In addition, the warp yarn tends to hang in the weaving process when the applied initial warp tension is low, which will cause chaotic shedding and yarn contact friction. 9 The initial warp tension applied to the warp yarn in the multi-layer weaving process should ensure clear multi-layer shedding while reducing warp yarn wear.…”