Mechanical analysis on constant cross-section segment of fiber band in condensing zone during compact spinning

Abstract

It has been found through experiments that under the same spinning condition, the twist of the compact spun yarn is approximately and averagely 5% larger than that of traditional ring-spun yarn. The larger part of the twist is called additional twist. Since the additional twist affects the subsequent processing to some extent, it is worth studying carefully. A theoretical model for analyzing the additional twist of a fiber band with constant cross-section in the condensing zone of a cotton-type compact spinning machine through a mechanical discussion is presented in this paper. Factors affecting the additional twist of the yarn, including the pressure of the profile tube, the friction coefficient between the fiber band and the lattice apron, the length of the suction slot, and the curvature radius of the profile tube, are discussed by numerical integral analysis. The experimental results verified the proposed fiber band additional twist model.

Study on the model of semi-open-end twist in compact spinning with lattice apron

“…the suction slot angle. Therefore, the larger the suction slot angle, the greater the x component of tension T, and consequently the faster the fiber speed in x direction according to equation (2). That would lead to higher additional twists.…”

“…A clear understanding of the compact spinning mechanism is conducive to produce higher quality yarn. At present, research on compact spinning mainly focuses on the additional twist mechanism, 1,2 the airflow field, [3][4][5] and the structure and performance of the compact spun yarn compared with the conventional spun yarns. [6][7][8][9][10][11] In perforated-lattice negative-pressure type compact spinning, the twist of the compact yarn is about 3-10% higher than that of ring-spun yarn under the same spinning conditions.…”

Mechanical modeling of an arc-shaped suction slot for compact spinning and analysis of additional twists

“…Therefore, the governing equations for the additional twist of the condensed strand in an arc-shaped suction slot are equations (12), (15) and (16). According to the governing equations, we can see that the additional twist is independent of the designed twist.…”

“…Let the start point A of the arc-shaped suction slot be the initial point and C be the end point. After the boundary conditions are set, the additional twist t w can be obtained by solving equations (12), (15) and (16) using the Runge-Kutta method.…”

“…Wang et al. 14,15 divided the strand in a condensing region into three parts, and analyzed the process of strand’s cross-section changed from oval to round shape. These studies are based on a line-shaped suction slot (Figure 1).…”