精密电阻点焊伺服加压控制系统设计

Design of servo pressure control system for precision spot welding

针对电阻点焊气动加压方式存在的接触冲击力大、加压过程中压力波动大、焊接压力和电极位移不可控等缺点,设计了一种精密电阻点焊伺服加压控制系统。该系统采用伺服加压和弹簧随动相结合的加压方式,采用高精度压力传感器对电极压力检测反馈,基于DSP控制器实现焊接压力和电极位移的精密控制。采用分阶段控制方法,该系统即实现了电极快速下压,电极与工件软接触,又有利于优化焊接加压速度,具有更宽的工艺适应性。试验结果表明,系统加压速度快,压力曲线过渡平滑,焊接启动压力对焊接质量影响明显。

A servo pressure control system for precision spot welding was designed to solve the high mechanical impact,high pressure fluctuation,non-control of pressure and electrode position during spot welding process with pneumatic welding gun. The system adopted the compression mode of servo pressure and spring follow-up,and used high-precision pressure sensor to check the electrode pressure. Based on the DSP controller,the precise control of welding pressure and electrode displacement was realized. With the method of staged control,the system realized the electrode rapidly pressing down and contacting with the workpiece in a soft way,and it was also beneficial to optimize welding pressure speed,which has wider process adaptability. The experimental results show that the system has high pressure speed,smooth transition of pressure curve,and obvious influence of welding starting pressure on welding quality.