A Flexible Computer-Controlled Experimental Power Source for Welding Research

Control of the Gas Metal Arc welding process is becoming increasingly sophisticated, due to improvements in technology and a better understanding of the process itself. To effectively conduct research in this area, it is necessary to have equipment that is extremely flexible in both architecture and operation. Experimental power sources and a welding test facility have been developed at the University of Wollongong which meet these criteria. The core time-critical control functions are performed by an independent digital signal processor (DSP). Non time-critical functions such as data storage and operator interface are performed by a desktop personal computer. Both computing platforms are readily programmable, allowing a variety of control strategies to be tested merely by changing software. Welding current is supplied to the process using a custom-built electronic power source with very high dynamic response and rapid current turn-off. The electrode feeding is accomplished by a bidirectional wire feed unit with a time constant of approximately 2 milliseconds. Visualisation of the welding process is achieved through the use of a CCD camera and high-power xenon flash unit, which are both synchronised to process events by the DSP controller. The construction of the welding test facility is modular, allowing for upgrading of submodules as technology improves. The inherent flexibility of the architecture also allows for another arc welding process, such as Gas Tungsten Arc welding, to be operated simultaneously.