Dynamic tension control for warp beams on sizing machine based on unwinding length monitoring

The traditional tension control method with tension as the control target is to uniformly control multiple warp beams and has low control accuracy. Simultaneously, it is difficult to install an independent sensor for a single warp beam to achieve a closed-loop control, due to the space limitation. Combined with the theoretical model, this paper proposes a novel method to achieve the closed-loop unwinding tension control of warp beams by taking the unwinding length as the control target and using the self-developed turns measuring device. First, the dynamic model between different factors and unwinding tension was established in this study. Furthermore, the influence of unwinding radius, unwinding speed and winding density on the tension was investigated to clarify the fluctuation mechanism. Based on these, simulation experiments were conducted for verifying the control effect of the proposed method. The results showed that the proposed single warp beam unwinding tension control method can achieve constant tension throughout the unwinding process, which is superior to the empirical open-loop control method that adjusts the tension according to the linear proportional change of the braking torque. Meanwhile, it has the similar control effect as the ideal closed-loop tension control method, maintaining stability under different reference tensions and disturbances. In addition, the proposed multiple warp beams unwinding tension control method also outperformed the traditional unified tension control method. Our measuring device can be easily installed on the single warp beam for control, resulting in consistent tension between multiple warp beams. Therefore, the proposed methods have a certain control effect and application value.