Mathematical modelling and improved control system for reducing warp yarn tension fluctuation in sizing machines

Abstract

In the sizing process, warp yarn tension often fluctuates when the residual yarn of the warp beam is approximately 35% of the full beam with a typical closed-loop tension control system. It affects sizing quality and the uniformity of the fabric’s appearance. Therefore, this paper first establishes the theoretical models of the warp yarn unwinding process and tension control system to clarify the warp yarn tension fluctuations mechanism. Subsequently, control system improvement methods are proposed and verified through simulations based on these models, including the addition of an independent air pressure device and a segmented control approach. Finally, the rationality of the proposed models and methods are experimentally confirmed using the constructed detection devices. Simulation analysis revealed that constant tension system control parameters and uneven moment of inertia of the warp beam cause system oscillations and larger yarn tension fluctuations. By installing air pressure device and implementing segmented control, the yarn tension fluctuation range is reduced by 83.16% and 89.44% respectively. Additionally, experimental results further indicated that the proposed models and improved control system are effective. Thus, this paper provides a significant theoretical foundation and practical guidance for stabilising unwinding tension in sizing machines, with potential applications across the textile industry