摩擦焊接过程电液控制系统性能分析

为提高摩擦焊接过程控制及焊接质量的可靠性与稳定性，分析摩擦焊机电液比例系统的动态控制品质,并为其配置合适的闭环控制系统。对摩擦焊机电液比例系统的静、动态品质进行了测试和分析，首次提出了摩擦焊接过程电液比例系统的传递函数。测试结果表明：该电液比例系统主要由延迟环节和惯性环节串联组成；其静态品质指标，控制精度和系统稳定性均良好。系统的动态响应性能优于伺服阀单腔工作状态的摩擦焊机电液伺服系统，略低于伺服阀双腔工作状态的摩擦焊机电液伺服系统，但抗干扰能力、可靠性均优于摩擦焊机电液伺服系统。通过建立系统传递函数，确定了计算机数字PID调节器的控制参数，实现了摩擦焊接过程中焊接压力的闭环控制，焊接压力的相对偏差小于3％。

A Cost Effective Closed-Loop Control System for Improving Performance of Chinese C25 Type Friction Welding Machine

Since 1990 we have engaged in research on closed-loop control system for friction welding machine. Our research has led to a cost effective closed-loop control system for improving performance of Chinese C25 type friction welding machine; this control system has been used in trial production since the beginning of 2000 and improved the performance of C25 type machine to the user's satisfaction so far. We tested and analyzed the static and dynamic control characteristics of the electro-hydraulic proportional control system, i.e. , our closed-loop control system. We put forward Eq. (3) as the transfer function for the first time in China. The electro-hydraulic proportional control system consists of a delay unit and an inertia unit connected in series. Test results show that our electro-hydraulic control system improves the static control characteristics of the C25 type friction welding machine. Electro-hydraulic servo system, widely used in developed countries as a closed-loop control system, turned out to be not sufficiently good in anti-jamming capability and reliability under Chinese conditions. Our choice of electro-hydraulic proportional control system ensures sufficient anti-jamming capability and reliability. The relative error of welding pressure control is less than 3% during the friction welding process.