Spot welding machine, also known as resistance welding machine, is the principle of welding by using the resistance heat generated by the current through the workpiece welding joint. When working, the two electrodes squeeze the workpiece, so that the two layers of metal form a certain contact resistance under the pressure of the two electrodes. When the welding current flows from one electrode to the other, instantaneous thermal welding is formed at the two contact resistance points, and the welding current flows instantaneously along the two workpieces from the other electrode, forming a loop without destroying the internal structure of the workpiece to be welded.
During the spot welding process, the surface of the weldment is cleaned up, sent between the upper and lower electrodes, and pressure is applied to make good contact; The contact surfaces of the two workpieces to be heated are energized and locally melted to form a molten core; Maintain the pressure after the power off, so that the molten core cools and solidifies under pressure to form a solder joint; Remove the pressure and remove the workpiece.
Spot welding process parameters such as welding current, electrode pressure, power-on time and electrode working face size have a great influence on welding quality. The process of spot welding is to open the cooling water; Clean the surface of the weldment, accurately assemble it and send it between the upper and lower electrodes, and pressurize it to make good contact; The contact surfaces of the two workpieces to be heated are energized and locally melted to form a molten core; Maintain the pressure after the power off, so that the molten core cools and solidifies under pressure to form a solder joint; Remove the pressure and remove the workpiece. Preparation and installation of weldments: Before welding steel weldments, all dirt, oil, oxide scale and rust must be removed. For hot-rolled steel, it is best to pickle and blast the welded part or remove the oxide scale with a grinding wheel. Although uncleaned weldments can be spot welded, the service life of the electrodes is seriously reduced, and the output power and quality of spot welding are reduced together. Mild steel in thin coating can be welded directly.
