Papers by Keyword: Yarn Tension

Abstract: The twisting of yarn in one of the most widely used conventional ring spinning processes is based on the ring/traveler system. The existing limitation of productivity in the ring spinning process lies on the prevailing force relation between ring, traveler and yarn as well as the frictional heat between traveler and ring, principally in the ring traveler system. Recently, a frictional free twisting element based on a superconducting magnetic bearing (SMB) was developed to increase the productivity of ring spinning drastically, which was patented by ITM and Leibniz IFW Dresden. This SMB consists of a circular superconductor and a permanent magnet (PM) ring. In the superconducting state, the PM ring levitates and can freely rotate even up to an angular speed of 50.000 rpm. It is connected with the spindle via the yarn through a guide attached to the PM ring to impart yarn twist. Through the rotation of the PM ring, the twist propagates to the nip point of the delivery rollers. The twist propagation rate depends on different parameters, e.g., spindle speed, balloon geometry, and friction between yarn and yarn guides. A change in the level of twist affects the process, yarn tension, yarn breakage rate, and yarn properties. Hence, it is important to investigate the twist distribution to derive effective measures for improving the twist propagation especially at higher angular spindle speeds and thus eliminate weak points to increase process stability and yarn quality. The aim of these measurements is to analyze the twist distribution along the yarn path to understand the causes of yarn breakages. In this study, the yarn path was traced at different regions by in-situ measuring the helix angle of twisted yarn using a high-speed camera. From the recorded images, the number of twists per unit length was determined using the image processing software ‘Image J’. Thus, the measurement method allows a new insight into the problem of yarn breakages originating from twist propagation in order to take optimized measures at higher angular spindle speeds.

Abstract: Concerning the intelligent technique control of automatic winder in textile production, the tension of yarn in unwinding and winding process is a key factor among various technical parameters, the speed known as linear and rotational speed and the position of yarn layer on bobbin will definitely affect the dynamic tension of yarn during the winding process. the photoelectric encoder sonser is used for measurement of the rotationtional and linear speed of cyclinder of winder machine. Position sonser can detect the amount of the remaind yarn layer on bobbin so as to regulate the position of the tension controller to make the dynamic tension to be uniform and approporite.

Abstract: For building high precision yarn tension control model, grey prediction method was first employed in this paper. The commonly used GM(1,1) model was modified by means of changing the coefficient a and b. Then the next tension value was forecasted from the previous test values by the modified GM(1,1) model. Then the forecasted values and the referred value were import into the self-adaption PID model. And the PID model output the control sign to magnetic particle clutch. The simulation of the control algorithm was completed in MATLAB 7.0. The simulation result showed that the proposed control algorithm had better precision than general PID and general grey prediction control algorithm.

Abstract: The yarn tension is an important parameter to determine the product quality and production efficiency in winding process. Appropriate winding tension makes the winding bobbin form, which is a compact structure without damaging the physical and mechanical properties, is conductive to smoothly unwinding after the back working procedure.This paper makes analysis of The principle, composition and factors affecting the yarn tension of a winding machine, so as to control the yarn tension constancy of the yarn theoretical basis.

Abstract: When winding yarn, the yarn tension control of a winding machine affects the quality of yarn subsequent processing. For randomicity and instability of the yarn tension in a winding machine, the paper designed a yarn tension control system based on analyzing conventional PID controller, using the fuzzy PID control algorithm to control the yarn tension system and realizing on-line self-adjustment of PID control parameters. The simulation experiment showed that system tension had better response using fuzzy PID control and eliminated nonlinearity and uncertainty of the system.

Abstract: We derive the system of coupled nonlinear differential equations that govern the motion of yarn in general. The equations are written in a (non-uniformly) rotating observation frame and are thus appropriate for description of over-end unwinding of yarn from stationary packages. We comment on physical significance of virtual forces that appear in a non-inertial frame and we devote particular attention to a lesser known force, that only appears in non-uniformly rotating frames. We show that this force should be taken into account when the unwinding point is near the edges of the package, when the quasi-stationary approximation is not valid because the angular velocity is changing with time. The additional force has an influence on the yarn dynamics in this transient regime where the movement of yarn becomes complex and can lead to yarn slipping and even breaking.

Abstract: Mathematical modeling can be used to simulate the unwinding of yarn from packages of different shapes. This method can be applied to design packages that can sustain high unwinding velocities at low and steady tension in the yarn. In the case of conic packages the angular velocity of unwinding depends not only on the winding angle as is the case for cylindric packages, but also on the apex angle. We will show that the dimensionless angular velocity depends very little on the apex angle. The apex angle, however, also determines the effective radius of the package at the lift-off point, therefore the angular velocity can be proportionally higher. We will compare unwinding from a cylindrical and a conic package with equal smallest radius and show that unwinding from the conic package is faster due to higher average radius of the package at the lift-off point.

Abstract: Stability of the yarn unwinding directly affects the efficiency of the textile production process and the quality of the final product. A package with an optimal shape will result in an optimal shape of the balloon. In addition, the yarn tension will be small and steady even at high unwinding velocity. Computer modeling is a valuable tool in the search for the optimal package shape. We demonstrate a mathematical model for simulating the unwinding from cylindrical and conic packages. We show how the winding angle and the apex angle influence the angular velocity of the yarn during the unwinding. Since the centrifugal forces on the yarn in the balloon depend on the angular velocity, this velocity has a large influence on the tension that we wish to reduce.

Abstract: As to the disadvantages of traditional contact measurement methods, a non-contact measurement system of yarn tension based on CCD technology is developed, which includes the system working principal and the structure ,the design of area matrix CCD driving circuit, the binary process of video signal boundary features by comparison method. Experimental data from contact measurement and non-contact measurement is contrasted, and the measurement error is analyzed. Experimental results show it is achieved with high accuracy and reliability.

Abstract: The yarn tension is a key factor to accurately control carpet pile height, which changes with the yarn path and the path flexing. The purpose of this paper is to find the relationship between yarn path and yarn tension and provide a basis for the yarn tension controller design. Firstly, tufting equipment system components and basic principle of tufting carpet is introduced. Then, the yarn path during weaving tufting carpet including yarn feeding parts, yarn guiders and tufting needle is constructed and yarn flexing in the yarn path is analyzed. After discussing yarn tension change caused by the path flexing, it is concluded that yarn tension changes with the tufting needle position and periodic change with the yarn flexing periodic change.