Design of hybrid ultrasonic frequency pulsed GMAW power source

A new type of gas metal arc welding (GMAW) method was proposed and a novel hybrid ultrasonic frequency pulsed GMAW power source was developed. In this method, an ultrasonic frequency pulse current was superposed upon the conventional pulsed GMAW current with frequency from 20 to 80 kHz, current amplitude from 0 to 100 A, and duty cycle from 0% to 100%. Main circuit topology in parallel structure and dual-processor digital control system consisting of MCU and DSP were designed. Synchronized output and different logical combinations of current given signal and PWM signal were realized through software programming, resulting in several output current waveforms for different work modes. Testing results of the output current indicate that output current waveforms of the designed hybrid ultrasonic frequency pulsed GMAW power source satisfy the requirement of different work modes with a fast current rising and falling rate even at ultrasonic frequency pulse current frequency of 80 kHz. Aluminium alloy bead-on-plate experiment was conducted with this power source and a good weld bead appearance was obtained.