Abstract:

Objective With the continuous development of three-dimensional textile technology, composite materials with three-dimensional fabric as the skeleton are increasingly emerging. The design and manufacture of 3D looms with better performance has become one of the key factors in improving the performance of composite materials reinforced with 3D fabric preforms. In the research and development of three-dimensional loom, the warp tension control is the core of the control in the weaving process, too high tension may lead to yarn breakage, and too small tension will affect the effect of fabric forming. Therefore, it is necessary to study the control of the warp tension of each layer under different yarn path conditions, as well as the corresponding control algorithm. In order to ensure the stability and uniformity of the warp tension.

Method In view of the characteristics of the multi-layer let-off system and the analysis of the main influencing factors of the warp tension, the let-off control system adopts the control concept of distributed control and centralized management, fully considers the requirements of the multi-channel multi-function and fast servo operation function of the control system, designs and adopts the combined PID (Proportional-Integral-Derivative Control) algorithm to realize the constant tension control, uses the direct control method to control the warp feed volume, and proposes a warp beam diameter estimation method for the multi-warp beam structure to ensure sufficient warp feed volume. According to the dynamic tension change, the tension pendulum and the angle sensor are combined to detect the balance position deviation, and the PID algorithm is used to control the tension of the war-off motor rewinding and unwinding speed control system in real time, so that it is in a relatively stable state. The let-off control algorithm is simulated, and the let-off control algorithm is verified and optimized through simulation analysis. Simulation simulates the response of the system under different operating conditions and evaluates the performance of the control algorithm. This process helps to identify potential problems and solve them, improving the stability and reliability of the system.

Results The fluctuation monitoring results of the tension balance pendulum rod of warp beams 1, 6 and 12 during the weaving process show that the tension curve shows a continuous change. At 28 seconds and 32 seconds (the up and down arrows indicate the disturbance of the opening motion), the effect of the opening motion of the heald frame on the tension is the most frequent, showing periodic fluctuations. Due to the different distances between the heald frame and the warp axis of each weft opening, the degree of interference between the rise and fall of the heald frame on the tension pendulum is also different. The maximum observed angle of interference is 0.47°. At 1 min and 20 s, there is a tension fluctuation caused by the beating motion, and after the interference occurs, the main controller uses the speed mode integral separation PID algorithm to quickly control the rewinding and unwinding response of the warp beam 1 motor, so that the pendulum 1 quickly returns to the set position and stabilizes within ±1°. At 1 minute and 30 seconds, there is a tension fluctuation caused by the let-off traction movement, and the basic let-off amount is compensated by the position mode, and the fluctuation of the stable tension pendulum is within ±1°. This shows that the control algorithm has a strong anti-interference ability, and in the face of various motion interferences, each warp axis can respond quickly, adjust the winding and unwinding, and send out a precise basic let-off amount to keep the tension pendulum in a dynamic equilibrium state.

Conclusion Through the analysis of tension fluctuation in the continuous weaving of No. 1, 6 and 12 warp beams, it can be seen that when disturbed, the tension fluctuation of each warp beam is consistent. When the let-off traction is synchronized, the position mode is used to calculate the influence of the tension fluctuation caused by the speed difference and the decrease in the diameter of the warp beam caused by the basic let-off amount to compensate for the speed difference, and control the synchronous movement of all warp beams. After the speed mode integral separation PID algorithm is used to adjust the tension pendulum of each warp beam to receive interference signals such as opening and weft beating, it can quickly and independently adjust each warp beam motor, so that the tension pendulum of each warp beam can be dynamically balanced and maintained near the target value. Therefore, the control system uses EtherCAT fieldbus communication and adopts the combined PID algorithm to carry out real-time synchronous control and independent control of each warp axis, and each warp axis can respond quickly to meet the tension control requirements of the angular loom.

Key words: quartz fiber, angle interlock fabric, let-off system, tension control, angle interlock loom, simulation