Study Of Laser-TIG Hybrid Welding Technique Based On Phase Matching Control

Laser-arc hybrid welding technology was proposed in the1970s by Steen W. M at Imperial College London, United Kingdom. This efficient and high-quality forming technology based on the merits of both laser technology and arc technology couples the laser and the arc in one weld pool that greatly improves their respective weaknesses. This paper developed a hybrid welding phase matching control system, and studied welding technique of AZ61magnesium by using this phase matching control system.Built a data acquision and analysis system based on hall sensor, signal process circuit and NI PCI-6221data acquisition card, which used to analyse the arc current and voltage. Developed a hybrid welding phase matching control system based on Labview9.30and NI-DAQ function libraries, which puts forward the trigger lock algorithm, which realizes the accurate and stable trigger of the laser pulse. Developed a test module for hardware system, realizes the accurate measurement of the hardware system characteristic parameters.The formations of welding joint surfaces and the change regulations of welding penetrations of magnesium alloy AZ61are studied with the utilization of this system in two typical phase matching patterns that the laser acts on the arc crest and the arc trough. Electric-arc shapes during welding are captured by the high-speed camera. The results indicate that the weld joint formation would be better performed when the laser acts on the AC arc crest than that on the AC arc trough; the penetration of weld forming when the laser acts on the AC arc trough is deeper than that when the laser acts on the AC arc crest.Studied the different formation under different matching control, and analyzed the reason of the difference formation. The significant variation differences of the weld joint formation and the weld penetration are mainly caused by different compressions on the electric-arc conductive channel exerted by the laser, and different valid thermal inputs of the positive and negative half-waves of the AC arc.Developed a laser pulse distribution control system which based on C++. The system combines the locking trigger algorithm, put forward a new control method and made the trigger delay time from several milliseconds down to less than one millisecond, at the same time provided the characteristics of the laser pulse distribution. Laser pulse can be activated by this system to act continuously and accurately on specified phase positions of the arc.