【作者】 王军；

【导师】 罗震；

【作者基本信息】 天津大学 ， 材料加工工程， 2007， 硕士

【摘要】 电极压力是电阻点焊的主要参数之一,电极压力的恒定性、可调性对于保证焊点的质量是非常重要的,但是,目前生产中普遍使用的气动焊枪,不具备调节电极压力的功能。本文的目的就是研制一种新型的伺服驱动的悬挂式点焊枪,该焊枪能够在焊接的过程中对电极压力进行实时的调节,从而实现复杂的焊接循环,提高焊接质量。焊枪采用伺服电机作为动力装置,以滚珠丝杠为主要传动机构,结构简单紧凑,运动平稳灵活。压力控制系统采用32位的ARM微处理器作为核心,与采用传统的单片机相比,系统的工作频率大幅提高,硬件功能更加强大,更适合电极压力的实时控制。此外,在系统中移植了uC/OS-II实时操作系统,并在此基础上构建了一个分层次的、多任务的、消息机制的软件系统,充分发挥了ARM的性能,提高了系统的稳定性和实时性。利用伺服焊枪进行了焊接试验,在焊接过程中,伺服电机工作在力矩模式下,采用开环的控制方式,利用电压信号控制电极的压力和速度,通过驱动器的反馈信号检测电极的压力和位置,使用I/O口控制焊接电源。实验结果证明,本课题研制的伺服焊枪的机械装置的精度和响应速度均能够满足焊接的需要,而且可以实现快速渐进,低速爬行,电极轻接触,快速预压等功能,有助于延长电极寿命和提高焊接效率。而且,使用伺服焊枪进行了低碳钢焊接试验,采用马鞍形的加压方式,与恒定压力条件相比,焊接中飞溅大幅减少,焊点强度和塑性增加,焊接质量有明显提高。更多还原

【Abstract】 Electrode pressure is one of the main factor of resistance spot welding,whoes stablility and convertibility are very important to assuring good welding quality.But air-driven welding gun which is widely used in factories can not change electrode pressure at all. So this paper tends to design a new type of hanging spot welding sevo gun, which is capable of changing the electrode pressure in real time during welding process, in order to carry out complex welding circles and improve welding quality.The gun is driven by servo motor and has a ball screw as its main transmission part. It is designed simply and compactly and moves smoothly and fexiblely.The system empolys 32-bit ARM micro-controller as the controlling core. Compared to using traditional MCU, the system is provided with much higher frequnency and more powerfull hardware. More over, real-time operating system uC/OS-II is migrated into the system, base on which a layed, multi-tasks and message-driven software system is founded, which fully makes good use of the advantage of ARM and brings better stability and more rapid response.During spot welding, servo motor is working in the torque mode. Electrode’s pressure and moving speed can be controlled by analog voltage input. Electrode’s pressure and position can be measured by the feedback signal from the motor drive. And the welding current can be controlled by common I/O.Thus an open loop controlling system is formed.Experimental results prove that the gun’s accuracy and response time can all meet the welding needs and it has many more functions, such as high-speed reaching, low-speed crawling, gently electrode touching, short-time pre-pressing and so on., which are very important to expand electrode life and improve welding efficiency. Further more, the servo gun can offer saddle shaped electrode pressure in the mild steel welding experiment. In comparison with constant electrode pressure, it can efficiently reduce welding expulsion, improve the weld’s intension and plasticity, and obviously improve the welding quality.更多还原