波控短路过渡CO_2焊接恒频自适应控制系统

针对短路过渡ＣＯ２焊接工艺的特殊性，基于熔滴与熔池短路阶　段电源输出回路电阻的变化特征，确定了有利于消除瞬时短路及提高熔滴过渡规则性的焊接　电源输出电流波形。在对短路过渡频率及焊丝伸出长度进行实时检测的基础上，采用ＭＣ６８ＨＣ　１１Ａ１单片机为主控ＣＰＵ，　建立了焊丝伸出长度变化前馈补偿—短路过渡频率负反馈控制的波控短路过渡ＣＯ２焊接恒频自适应控制系统，以提高焊接工艺过程的稳定性、抑制焊丝伸出长度变化对焊接工艺过程的扰动。

ADAPTIVE CONTROL SYSTEM WITH CONSTANT FREQUENCY OF DROPLET TRANSFER FOR WAVEFORM CONTROLLED SHORT-CIRCUITING CO_2 ARC WELDING

Considering the particular feature of short circuiting CO2 arc welding process, the output current waveform of welding power source is determined based on the characteristic of the output loop resistance during the period of droplet short circuiting with weld pool. The current waveform is in favor of eliminating the instantaneous contact of droplet with weld pool and enhancing the regularity of droplet transfer. An adaptive control system with constant frequency of droplet transfer is established after the droplet transfer frequency and the wire extension being detected in the real time. The control system is aimed at improving the stability of welding process which is realized by the feedback control of transfer frequency, and restraining the disturbance inducing by the variation of wire extension which is compensated through its feedforward. The basis of the system is an inverter type arc welding power source controlling by a microcomputer MC68HC11A1.