脉冲旁路耦合电弧MIG焊的动态数学建模及过程控制

脉冲旁路耦合电弧熔化极惰性气体保护(Metal inert-gas, MIG)焊是一种新型的低热输入焊接方法，它通过特定的接法引入旁路电弧与主路电弧实现热、力的耦合，利用旁路电弧的分流作用，实现熔化母材热量与熔化焊丝热量的独立控制，从而在精确控制母材热输入的同时保证熔滴的自由过渡形式，可以实现铝-钢等异种金属的连接。为了理论分析不同焊接参数对焊接过程的影响，通过等效、线性化处理与迭代数值求解算法，建立可以正确描述焊接物理过程的动态数学解析模型；针对焊接过程中耦合电弧稳定性较差且直接影响焊接质量的问题，提出通过检测弧压波动的反馈信号、实时调节送丝速度、进而控制耦合电弧稳定性的闭环控制方案，并基于快速原型系统进行焊接过程控制仿真与试验。仿真结果表明，当焊接过程受到干扰后，采用闭环控制方案可以显著提高耦合电弧的稳定性；焊接试验证明了控制仿真的预测与分析，进行闭环控制后，焊接过程更加稳定同时得到了成形良好的铝-钢异种金属接头。

Modeling and Control of Pulsed Double-electrode MIG Welding Process

Pulsed double-electrode metal inert gas welding is a new kind of low heat input welding method. With different connection, parts of welding current bypassed and it controlled the base metal current and melting current separately. With free-flight metal transfer process, it could weld dissimilar metals. Aiming at the unstability of coupling arc in pulsed double-electrode metal inert gas welding process, a dynamic mathematic model has been built to truly describe and simulate the welding process with equivalent simplification, linearization and iterative solution. Then a control scheme is put forward and simulated, which changes the wire feed speed to adjust the main arc length, and further to control the stability of the coupling arc. Also the welding experiments with control scheme are carried based rapid prototyping system. Simulations proved the effectiveness of control scheme. And with controlling, the welding experiment is more stable and a good Al-Fe joint is acquired.