THE WORKING METHODS OF LASER WELDING
There are many advantages of laser welding, such as high aspect ratio, deep and narrow welds, bright and beautiful welds. And because of the high power density, the melting work is extremely fast, the heat input to the workpiece is very low, the welding speed is faster, the thermal deformation is small, and the heat-affected zone is small. In addition, due to the high density of laser welding, during the welding process, the molten pool is continuously stirred, and the gas is easy to come out, resulting in the formation of non-porous penetration welds. The high cooling efficiency after welding is easy to make the weld microstructure, and the weld strength, toughness, and comprehensive performance are high.
In laser welding, the technology of strong weld seam, high-temperature heat source, and full absorption of non-metallic material components have a purification effect, reduce the content of impurities, change the size of inclusions and their distribution in the molten pool, and do not use electrodes or filler wires in welding work. , the melting zone is less damaged, so that the strength and toughness of the weld are at least equal to or even higher than that of the parent metal.
Easy to operate, because the focused spot is small, the welding seam can be positioned with high precision, the beam is easy to transmit and manipulate, and it is not necessary to replace the welding torch and nozzle frequently, which significantly reduces the auxiliary time of downtime. emergency stop and restart. And it is non-contact, atmospheric environment welding work. Since the energy comes from the laser, there is no physical contact between the workpieces, so no force is applied to the workpieces. In addition, the magnetic field has no effect on laser welding.
And because of the low average heat input and high machining accuracy, the cost of reprocessing can be reduced, and the operating cost of laser welding is low, which can reduce the cost of the workpiece. It is also easy to automate, enabling efficient manipulation of beam intensity and fine positioning.
According to the working method of laser welding, it can be divided into:
Galvo welding uses the fast scanning function of the galvanometer to preset parameters such as the welding path and laser energy manipulation on the computer. The welding speed is faster, the precision is high, and the beam pattern is good. It is a method of fine welding.
Lap Welding/Stitch Welding This is a welding method that extends two sheets. The thickness and material of the sheets can be the same or different. They are widely used in the production of automobiles, container shells, metal frames, and file cabinets.
Laser spot welding uses high-energy laser pulses generated by a laser to instantly heat the metal, forming a short-lived molten pool that solidifies before the next pulse. Faster speed, high efficiency, large height, small deformation, small heat-affected zone, more commonly used in jewelry, advertising word welding, etc.
There are two types of penetration welding, one is by heat conduction, the heat is transmitted through the upper material to the lower contact surface so that the two materials are welded together. The other is that the laser passes through the transparent material above (such as plastic, etc.) to heat the material below so that the upper and lower materials are welded together.
Swing welding is also called wobbling welding. Along the trajectory of the weld during the welding job, the laser beam is oscillated to improve the tolerance requirements of the weld and reduce the effect of porosity in the weld.
In laser welding, fine manipulation of laser power is very important for the quality of the weld, especially at the beginning and end of the weld. In different stages of the melting work, the absorption rate and reflectivity of the metal to the laser are quite different. Experiments show that at the beginning and end of welding, the laser power is controlled by segmented power, which can obtain better welding quality. However, laser welding without segmental control is prone to the obvious locomotive and stern effects at the start and end stages.