Study On Character Of Laser-MIG Hybrid Welding Based On Pulse Scatter Distribution Control System

In this paper, the laser pulse scatter distribution controlling system is developed, the function of laser pulse to drop transfer and the character of laser-MIG hybrid welding of aluminum alloy is studied by using this system.For the mutual relations among laser pulse, pulse arc and droplet in laser-MIG hybrid welding, we develop the laser pulse scatter distribution control system based on Visual C++, the system has advantages such as high efficiency, high trigger precision, short delay time. The delay time of the system is about400us.The drop transfer is studied by using this system in the process of hybrid welding, the results show that the droplet is attracted to depart from the axis more easily with the increase of laser power during the laser pulse acting on the peak value, and the angle between the path of droplet entering into melt pool and wire axis increases with the increasing of the laser power, but there is no significant change during the laser pulse acting on the basic value. The time of droplet entering into melt pool is shorter than that without laser. The time of droplet entering into melt pool is reduced with the increase of the laser power. And the time with laser acting on the basic value is shorter than that with laser acting on the peak value.By means of analyzing the force on the droplet, the laser pulse mainly changes the electromagnetic force to arouse above-mentioned change. The laser pulse mainly influences the necking and shedding of the droplet when the laser pulse scatter acts on the peak value of the MIG waveform. The laser pulse mainly results in the increasing of the electromagnetic pressure difference between the electrode and the surface of workpiece during the laser pulse acts on the basic value. The electromagnetic pressure difference causes the change of the plasma flow force. Both the effect of the mode of action has a tendency to increase with the increase of laser power.We conduct the surface welding and butt welding experiment under pulse scatter distribution control system for aluminum alloy. For MIG surface welding, the weld appearance is discontinuous when the welding speed is1500mm/min. The weld appearance with laser pulse scatter acting on the basic value is better than that with laser pulse scatter acting on the peak value. Through calculation, critical welding speed can be increased by25%after laser joining. For tensile properties test of MIG welding and hybrid welding butt, MIG welding tensile strength is185Mpa,65%of the parent metal tensile strength; hybrid welding tensile strength is203Mpa,71%of the parent metal tensile strength. Compared the microstructure and microhardness of the MIG welding and hybrid welding, grains of hybrid welding seam is small than the MIG welding, and the microhardness of hybrid welding joint is higher than the MIG welding.