Spot welding refers to the welding method in which a cylindrical electrode is used to form a solder joint between the contact surfaces of two overlapping workpieces during the welding process. In spot welding, pressure is applied to make the workpiece close contact, and then the current is switched on. Under the action of resistance heat, the workpiece contact part melts, and forms a solder joint after cooling. Spot welding is mainly used for the welding of sheet metal parts with a thickness of less than 4mm, especially for the welding of automobile bodies, carriages and aircraft fuselages. However, containers with sealing requirements cannot be welded. The working principle of the laser spot welding machine is that the two electrodes generate an instantaneous short-circuit current, thus forming a high-temperature and high-pressure environment, so that the steel plate melts and crystallizes during the cooling process, and the two steel plates are joined together.
The advantage of this method is that it can weld and combine multi-layer steel plates, but the disadvantage is that the heat and pressure generated during the welding process can not be well controlled, so the welded steel plate needs longer cooling time and is prone to thermal stress changes. If the pressure and heat are reduced to avoid thermal stress changes, it is easy to produce a state of incomplete welding.
Simply put, the laser welding machine is to weld two workpieces of the same material into a whole. For example, the welding of steel plates is essentially heating the steel plate, causing the material of the steel plate to liquefy at high temperatures. The welding method of the laser welding machine is to use high energy laser pulses to locally heat the material in a small area. The energy of the laser radiation is directed through heat transfer to the internal diffusion of the material, which is melted to form a specific molten pool. This is a new welding method.
Laser welding machine is mainly used for the welding of thin-wall materials and precision parts. It can realize spot welding, butt welding, lap welding, sealing welding, etc., high depth to 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 quality weld, no porosity, accurate control, small focus spot, high positioning accuracy, easy to realize automation.
In addition, during the cooling process, the two materials recondense into a single unit. In the welding process, heating and cooling time is very important. Due to the difference in time, the crystal after solidification of the steel plate can be divided into many kinds.
In general, the faster the heating and cooling process of the laser welding machine, the smaller the change in the original performance of the steel plate, the greater the reverse change, the less the characteristic change caused by welding, the more in line with the high-precision and high-demand welding processing requirements.
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