Spot welding machine electrodes are consumable parts of resistance welding machines. In welding equipment such as spot welding, seam welding, projection welding and butt welding, electrodes with certain mechanical and physical properties and specific shapes and sizes are used. The electrode is a tool used by the spot welder to transmit welding current and welding force to the weldment. In many welding situations, the electrode of the spot welder is still a welding mold, clamp or positioning device.
The working conditions of the electrode of the spot welder are relatively harsh, so in addition to the good electrical and thermal conductivity of the material used to make the electrode of the spot welder, it should also be able to withstand the effects of high temperature and high pressure. At present, the commonly used electrode materials of spot welders are copper and copper alloys. In special welding occasions, high temperature resistant powder sintered materials such as tungsten, molybdenum, and alumina are also used.
In resistance welding, the choice of electrode material and shape of the electrode of the spot welder directly affects the quality of the weldment, production cost and labor productivity, so it should be paid attention to in production. Based on the spot welding electrode, the spot welding machine electrode is widely used, and the working conditions are relatively harsh, and there are many varieties. This article will focus on this article.
Taking a common spot welder as an example, the main function of the electrode is to transmit current.
Transfer of current is the basic function of the electrode. Because the resistance of the welding circuit of the spot welder is very low and the resistance of the welding area is very small, in order to obtain sufficient heat to form a nugget in a short welding time, it must flow through the electrode of the spot welder to the weldment with a great current. Depending on the properties and thickness of the weld metal, the welding current is often as high as thousands to tens of thousands of amperes. At this time, the current density flowing through the working surface of the electrode of the spot welding machine is as high as hundreds to thousands of amperes per square millimeter. For example, the current density range of hard welding low carbon steel plate is 200 ~ 600A / mm2, the current density range of spot welding stainless steel is 300 ~ 400A / mm2, and the current density range of spot welding aluminum and aluminum alloy is 1000 ~ 2000A / mm2. Current density on the working surface of the electrode of the spot welder during spot welding of different thickness low carbon steel plates. It can be seen that this current density is tens to hundreds of times the safe current density of commonly used wires, and has far exceeded the level that ordinary wires can withstand.