【作者】 唐跃军；

【导师】 张涛；

【作者基本信息】 中南大学 ， 控制科学与工程， 2010， 硕士

【摘要】 在现代生产中,焊接技术已经得到了广泛的应用,它已经成为一种重要的生产手段。而脉冲MIG (Metal Inertia Gas)焊是一种高质量的焊接方法,在生产上已经越来越被重视。脉冲MIG焊是通过熔滴过渡实现焊接过程的,研究熔滴过渡的机理并加以控制,对稳定焊接过程、改善焊缝成形、减少飞溅等方面起到非常重要的作用。在分析了熔滴过渡的机理后,从熔滴过渡的控制目标出发,采用了双闭环控制方案对焊接电流及电弧电压进行控制。考虑到内环电流环能通过控制焊接电流波形来调节实现精确的熔滴过渡电流波形的功能,采用自适应控制算法对电流环进行控制。通过对电流环对象进行详细分析,建立了电流环被控对象的等效离散数学模型,在此基础上,设计了自校正调节器。根据焊接系统对象的动力学特征和控制性能,建立了脉冲MIG焊的数学模型,基于MATLAB/Simulink平台,构建了控制系统的仿真模型。通过分析焊接参数对熔滴过渡的影响,提出了一种保证熔滴尺寸稳定的熔滴过渡控制方案,并对这种方案和常用方案进行了仿真比较,验证了保证熔滴尺寸稳定的控制方案能减少能量的损耗。以DSP为控制核心,设计了脉冲MIG焊控制系统的硬件,采用模块化设计方法,利用汇编语言完成了软件设计。更多还原

【Abstract】 In modern production, the jointing technology has been widely applied, and it has become a vital production tool.As a high quality welding method, the pulsed MIG welding has become more and more important in industry production. Because the pulsed MIG welding complete the welding process through the metal transfer process, studying and controlling the metal transfer’s mechanism have fairly important affects to balance the welding process, improve the shaped welding slot and reduce the splash.After analyzing the mechanism of metal transfer, a double closed loop control scheme is adopted to control the welding current and electric-arc voltage based on control target of metal transfer. As the inner loop can acquire accurate metal transfer current graph by controlling the welding current graph, the adaptive control is adopted to control the welding current. After particular the inner loop is analyzed, an equivalent discrete math model of the current loop is established and a self-adjust adjustor based on the model is designed.A pulsed MIG welding math model is established by analyzing dynamics characters and control performances of the welding system, and a simulation model of the control system is conducted based on MATLAB/Simulink platform. At the end, after the welding parameters of the metal transfer process are analyzed, an improved metal transfer control scheme is put forward to guarantee drop size stabilization, and the simulation model was used to compare the improved scheme with the normal scheme. The simulation results show that the improved scheme can reduce wasted energies.A pulsed MIG welding hardware control system is designed by choosing DSP as the control core, and a pulsed MIG welding soft control system is designed based on assemble language by adopting modularize design method.更多还原