Waveform Controlling Strategy For CO₂ Welding And Its System Realization

In order to solve the problem of spatters in CO₂ welding, domestic and foreign scholars have done a lot of work .Extensive studies found that the waveform control can effectively reduce the spatter production in CO₂ short-circuit transfer welding .It is difficult for traditional control to satisfy to the requirement of waveform control .The introduction of digital technology, especially high-frequency switch have laid good foundation for accurate analysis and control of current, voltage wave in metal transfer process.In this paper , the progress of digital welding power source was profoundly studied. On the basis of various measures of reducing welding spatters, the self-optimizing waveform control strategy based on PI control was proposed. With the integration of regularly control and PI feedback control, the programme cleverly avoided the difficulty of necking detection in CO₂ short-circuit transfer welding ,and make the necking transfer in the set time ,under conditions of low-current to achieve the objective of reducing spatters by adjusting short-circuit current growth rate.The software system which include program of two-circuit PWM signal between which there was phasic difference of 180 degreed,A/D conversion, PID counting subroutine, asynchronous communication and basic subroutine in welding process was constructed by the designed programme. In addition, the stability and anti-interference issues which closely related to the system are discussed in detail.Finally some relational experiments were carried out. The result shows that the digital control system can work with relative hardware circuit well to realize kinds of functions in design,and the real-time ,correct output control waveform can be realized. This digital control system designed in this paper could be use to study on the digital technology of arc welding power source.