Determining tension of yarns when interacting with guides and operative parts of textile machinery having the torus form

Abstract

The research related to determining of the yarns tension when interacting with guide and operative parts of weaving looms and knitting machines having the form of torus in the area of contact with yarn established the mechanism of yarn tension increase behind the guide having the torus form due to change in geometrical dimensions and friction forces within contact area. It was proved that yarn tension increase behind the guide is effected by ratio of radius of internal circumference of torus to radius of working circumference; contact angle between yarn and working circumference of torus; radial contact angle between the yarn and internal surface of torus; physico-mechanical and structural properties of yarn. For multifilament and spun yarn, the actual contact angle is more than nominal one due to yarn diameter distortion in the contact area with surface of torus. Values of contact angles between yarns and working circumference and values of radial contact angles between yarns and internal torus surface shall be determined according to geometrical dimensions and design of guide and operative parts of weaving looms and knitting machines. The paper includes experimental research of interaction between different by its nature yarns and spun yarn (natural, synthetic, and man-made) and surfaces having the torus form imitating guide and operative parts of weaving looms and knitting machines. Based on experimental research the regression relationships between tension values behind the guide and ratio of radius of internal circumference of torus to working circumference radius, yarn tension prior it goes to guide and nominal value of contact angle were obtained for cotton, woolen, linen spun yarn, and polyamide multifilament. The analysis of the regression relationships made it possible to establish ultimate values of geometrical dimensions for guide having the form of torus when tension has its minimum value. This will enable minimization of the yarn tension during its processing on the weaving looms and knitting machines. This leads to a decrease in yarn breakages, an increase in the production equipment performance by reducing its downtime, improving the quality of the fabric and knitted garments produced. This suggests a practical value of the proposed technology solutions. These latter are related, in particular, to determining optimal geometric dimensions of guides and operative parts of weaving looms and knitting machines having the form of torus in the area of contact with yarn, at which the output tension will have the minimal required degree. Therefore, there is a good reason to claim the possibility of guided management of the process of changing the yarn tension in weaving looms and knitting machines by choosing geometrical dimensions of high-curved guide for specific yarn types.