The resistivity of a spot welding machine depends only on the type of metal used
The resistivity of a spot welding machine depends not only on the type of metal, but also on the heat treatment state, processing method, and temperature of the metal. Contact resistance exists for a short period of time, usually in the early stages of welding. Due to the presence of high resistance oxide or dirt layers on the surface of the workpiece and electrode, the current will be greatly hindered. Excessive oxide and dirt layers can even cause current failure. In the case of a very clean surface, due to the microscopic unevenness of the surface, the workpiece can only form contact points locally on the rough surface. The folding of current lines formed by contact points. Due to the reduction of the current path, the resistance of the contact point increases. Compared with the resistance Rew, Rc, and Rw between workpieces, the electrical resistivity and hardness of copper alloys are generally lower than those of workpieces, so their impact on the formation of fusion nuclei is smaller, and we rarely consider their influence. The influence of welding current on spot welding machine can be seen from the formula that the current has a greater impact on heat generation than resistance and time. Therefore, during the welding process, it is a strictly controlled parameter or secondary current.
1. The influence of welding time: In order to ensure the size of the fusion zone and the strength of the weld, welding time and welding current can complement each other within a certain range. To obtain a certain strength of solder joints, high current and short duration (strong conditions, also known as hard specifications) can be used, as well as low current and long duration (weak conditions, also known as soft specifications). The choice between hard and soft specifications depends on the performance, thickness, and power of the welding machine used for the metal. Spot welding machines have upper and lower limits on the current and time required for metals of different properties and thicknesses, which should be used as the standard. The electrode pressure has a significant impact on the total resistance R between two electrodes in spot welding. As the electrode pressure increases, R decreases significantly, but the increase in welding current is not significant and cannot affect the decrease in heat generation caused by the decrease in R.
2. The strength of solder joints always decreases with the increase of welding pressure. The solution is to increase the welding current while increasing the welding pressure. The shape and material properties of the electrode affect the oil leakage of the spot welding machine. Rotary oil rotates the cylinder drive. Avoiding oil pollution caused by lubricating oil during mechanical transmission. Improving welding molds can be applied to other situations that require sealed welding. Special alloy materials that require high-precision and high standard welding can choose medium frequency inverter spot welding machines, or some good welding controllers can be selected to match spot welding machines. The magnitude of the current is directly related to the age of the spot welding machine. After long-term experimental testing by our engineers, the no-load current of spot welding machines used for more than 3 months ranges from 8A to 15A, and sometimes even higher. Now let's take 11A as an example. Through long-term experimental observation of different types of enterprises, spot welding machines with working hours of more than 8 hours may require operators to adjust the position of the welded parts or other factors.
When spot welding with a spot welding machine, the heat generated is strictly controlled to form its core welding point, and the vast majority of the heat is lost during the process. The welding cycle of spot welding machines is mainly divided into two categories and four categories, namely spot welding and projection welding. We mainly introduce four basic stages. The electrode begins to mention the electrode, and the time begins to decrease again. After the time has passed, the next welding cycle begins.
During spot welding, the pre pressing stage requires eliminating gaps between thick workpieces to ensure a tight fit. When heating, sparks should be prevented from splashing, forging pressure should be increased, the molten core should be compacted, and cracks or shrinkage should be prevented. There are many learning opportunities in the welding process that require us to conduct in-depth research.
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