Microprocessor control of TIG welding system

At the start of the project, a hardwired controller existed for controlling the welding sequence required for pulsed TIG welding. Such a sequence controls the gas flow, arc current and torch movement. This controller has now been replaced by a microprocessor-based design. The system is described in this paper and it readily carries out the functions of the hardwired controller but, in addition, is able to store programs of the welding sequence parameters, operate visual displays and permit alteration by keyboard the value of any one of the parameters even while the weld is being created. The design is based upon the Intel 8080 microprocessor and all the necessary interfaces to the welding plant have been developed. The software was developed initially on a prototyping system and then a main frame computer (ICL 1906S). In order to test the developed controller, an experimental TIG welding apparatus has been constructed. The result of successful welding tests are given including photographs of sample welds. The project has clearly illustrated that microprocessors can be used in hostile electrical environments and the results presented are an important step in the development of a fully automated TIG welding system.