| With the demand of high efficient and automation in welding process, the hot wire TIG welding was publicly concerned by lots of professors, engineers both at home and abroad for its excellent qualities. Hot wire TIG welding power sources were separately comprised by TIG welding power source and wire heating power source right now. Based on the research and the development tendency of hot wire TIG welding power source, a pulsed hot wire TIG welding with single power source controlled by single chip was researched and designed. In order to heat wire during TIG welding, a turn-off switching tube was used in the main circuit.Firstly, the structure and control principle of main circuit in hot wire TIG welding with single power source were introduced. The main circuit includes rectifier, inverter, high-frequency transformer and wire heating circuit. Full bridge topological structure, the frequency of 22KHz, IGBT switching power device were adopted for inverter. Components selection and parameter calculate were definitely described.Secondly, the control circuit of hot wire TIG welding with single power source was introduced in detail. The control circuit was comprised with minimum system of single chip, parameters preset and display circuit, PWM circuit, data acquisition circuit, drive circuit, protect circuit and wire heating control circuit. Acquired current signal were inverse feed backed with PWM, then, output of the chip SG3525 were controlled through PI regulator. As a result, the external characteristic was controlled. HSO on chip was used for heating wire in pulse.Then, the design of software and the program structure for control system were analyzed. The software for control system was designed according to the timing requirement, the main program and the interrupt service program were highlighted. Several software anti-interference measures were taken, such as WDT, redundancy directive, digital filtering. The program flow chart and some of the key program were also showed.Finally, the offline and online debugging were done for this power source, and the relevant oscillograph traces were given. The experiment showed that heating synchronization of hot wire TIG welding with single power source could be achieved. In the base current period, wire were heated, while in the pulse current period, wire were melted. After the debugging, specimens were welded to test this power source, it is proved that this power source is suitable. According to problems showed during the process of debugging and welding, several suggestions were given for improvement in the future. |
