The influence of the curvature radius of the guiding surface on the tension of polyethylene and polyamide complex yarns during processing on weaving and knitting machines

Abstract

Researches that have been carried out to determine polyethylene and polyamide multifilament yarns tension when interacting with guides and operative parts (of large and small curvature) of looms and knitting machines, helped to establish the mechanism for the process of increase in polyethylene and polyamide multifilament yarns tension after the guide which can be attributed to friction forces in the contact area. It has been proved that increase in tension is explained by varying contact angle between polyethylene and polyamide multifilament yarns and large curved and small curved guides; notably, actual angle for multifilament yarns will be larger comparing to nominal one due to distortion of yarn’s cross-section in the contact area. Based on experimental researches for polyethylene and polyamide multifilament yarns, regression dependencies were obtained between the value of tension for polyethylene and polyamide multifilament yarns after the guides and tension before a guide, radius of guide surface curve, a contact angle. Analysis of these regression dependencies allowed to establish extreme values of guide’s curve radius at which tension will have the minimum value. As a result, it has been made possible (still at the initial stage of the computer aided manufacturing and usage of recursion) to determine polyethylene and polyamide multifilament yarns tension before fabric and knit formation area depending on geometric and design parameters of equipment and their mechanical and physical properties. Thereby leading to decrease in polyethylene and polyamide multifilament yarns breakages, increase in looms and knitting machines performance due to reduced downtime, and improvement of quality of manufactured fabric and knit. Whereby we can state that the offered engineering solutions are practically attractive. In particular, the latter deal with determining most suitable geometrical dimensions of guide and operative parts of looms and knitting machines, at which output tension will have minimum necessary value. The procedure has been determined to regulate directionally the process of change in yarns tension at looms and knitting machines by fitting of geometrical dimensions of large curved and small curved guides for polyethylene and polyamide multifilament yarns.