Resistance welding machine is currently one of the more advanced welding equipment in welding technology, and it is widely used and favored by welding industry professionals. However, with the increasing popularity of resistance welding, the maintenance and upkeep of the electrode heads of resistance welding machines have become increasingly important. So, why are the electrode heads damaged during the operation of resistance welding machines? Let's listen to the analysis below.
In the resistance welding process, two copper electrodes are pressed down and Joule heat is generated between the steel to be welded, resulting in a spot weld nugget that sticks the steel together. For galvanized steel plates, during resistance welding, the galvanized layer melts and seeps into the electrode, accumulating on the electrode surface. In the resistance welding process, due to high temperature and high pressure, a layer of Cu5Zn8 (copper zinc) alloy will accumulate on the electrode.
After multiple accumulations, the electrode will be covered by the accumulation layer, which may damage the electrode and even cause electrode fracture. Some alloy layers may peel off from the electrodes and stick to the metal plate, causing surface defects on the vehicle body. Although a portion of the alloy layer may fall off, most of it still adheres to the electrode surface, causing a decrease in the current passing through and deteriorating the welding conditions, even resulting in cold welding. Therefore, some measures must be taken to clean the electrode surface and maintain good welding conditions.
In addition to the issue of accumulation of galvanized materials, electrode shape, cooling conditions, steel, coatings, and welding guns can all cause electrode deformation or fracture. The method of increasing the current is unfavorable for the electrode, as a larger current will cause the end of the electrode cap to soften, promoting more diffusion of galvanized material on the electrode and resulting in thicker deposits on the electrode surface.
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