Spot welding refers to a welding method in which a cylindrical electrode is used to form a welding spot between the contact surfaces of two overlapping workpieces during welding. During spot welding, first pressurize the workpiece to make it contact closely, then connect the current, melt the workpiece contact under the action of resistance heat, and form the welding spot after cooling. Spot welding is mainly used for the welding of sheet metal components with a thickness of less than 4mm, especially for the welding of automobile body, carriage and aircraft fuselage. However, vessels with sealing requirements shall not be welded. The working principle of the laser spot welding machine is that the two electrodes generate an instantaneous short-circuit current, which turns into an environment with high temperature and pressure, so that the steel plate is melted, and crystals will be generated during the cooling process to combine the two steel plates.
The advantage of this method is that many layers of steel plates can be welded and combined, but the disadvantage is that the heat and pressure generated in the welding process can not be well controlled, so the steel plate after welding needs a longer time to cool, and it is easy to change the thermal stress. If the pressure and heat are reduced to avoid the change of thermal stress, It is easy to generate the condition of incomplete welding.
In short, the laser welding machine is used to weld two workpieces of the same material to make it a whole, such as steel plate welding. The welding process is essentially to heat the steel plate so that the material of the steel plate is liquefied at high temperature. The welding method of the laser welding machine is to use high-energy laser pulse to locally heat the material in a small area. The energy radiated by the laser is directed to the internal diffusion of the material through heat transfer, and the material is melted to form a specific molten pool. It is a new type of welding method. The laser welding machine is mainly aimed at the welding of thin-walled materials and precision parts. It can realize spot welding, butt welding, overlap welding, seal welding, etc. with high depth width ratio, small weld width, small heat affected zone, small deformation, fast welding speed, smooth and beautiful weld, no treatment or simple treatment after welding, high weld quality, no pores, accurate control, small focus light points and high positioning accuracy, Easy to automate.
Moreover, during the cooling process, the two materials are reconstituted into a whole. During the welding process, the heating and cooling time is very important. Due to their different time, the crystals of the steel plate after condensation can be divided into many varieties.
In general, the faster the heating and cooling processes of the laser welding machine are, the less the original properties of the steel plate will be changed. On the contrary, the greater the changes will be. The less the characteristics will be changed due to welding, and the more it meets the welding processing requirements of high precision and high requirements.
