What is resistance spot welding mainly used for welding? What are the purposes and principles

Resistance spot welding is a metal processing method that uses electric current to convert into heat energy through the resistance between the workpiece and the electrode, causing the surface of the workpiece to instantly melt. Under the melting state, pressure is applied to quickly solidify the melted part of the workpiece and form welding points with the electrode contact area. It is often used to connect metal components, such as car bodies, furniture, pipelines, etc. So, what is resistance spot welding mainly used for welding? This article will popularize the relevant knowledge of resistance spot welding for you.

1、 The purpose of resistance spot welding

Resistance spot welding is a welding method that generates resistance heat by flowing low voltage current through two pieces of metal clamped together, locally melting and applying pressure to weld them together. Resistance spot welding has many advantages:

1. Low welding cost, no consumption of welding wire, welding rod, and gas.

2. No smoke or steam is generated during welding.

3. The welding position is flexible and suitable for welding galvanized iron sheets.

4. The welding speed is fast, the quality is high, the heating range is small, and the workpiece is not easily deformed.

5. It is most commonly used in the manufacturing and repair of load-bearing vehicle bodies, especially suitable for multi-layer welding of thin plates.

During the welding process, the high temperature generated by resistance spot welding can instantly melt the metal material, forming a continuous connection between the metal materials. Therefore, resistance spot welding can ensure the continuity of the metal material at the welding point, thereby achieving the purpose of firm fixation.

Moreover, the welding temperature of resistance spot welding is higher, but the welding time is shorter. Compared to other methods, changes in welding temperature generally do not affect the properties of the metal material itself, and resistance spot welding can maintain the original properties of the metal material.

Because the electrode format used is very simple, resistance spot welding is flexible in the welding process and suitable for different metal materials. At the same time, the time and strength of resistance spot welding can be controlled, and unexpected results can be achieved by adjusting the current and voltage.

2、 The principle of resistance spot welding

During resistance spot welding, there are several main principles:

1. The principle of current heating: When current passes through a metal sheet, it generates a high amount of heat, which in a short period of time raises the spot welding point to the melting point, causing the metal sheet to melt and form a solder joint.

2. Pressure principle: When welding, applying appropriate pressure can tightly bond the metal plates together, which is conducive to forming a solid connection point.

3. Electrolytic principle: Due to the presence of electrolyte solution, current can accumulate and release heat at the spot welding site, promoting the melting of metal sheets.

In practical applications, resistance spot welding mainly includes the following two forms of variation:

1. Contact type resistance welding: In contact type resistance welding, both counter electrodes and diagonal electrodes can be used. The purpose is to allow current to pass through the joint to form heat, thereby melting the material and tightly bonding the welded joint.

2. Positive wave resistance welding: In positive wave resistance welding, the voltage is output through the welding device for a current cycle, and the current rises from the minimum value to the maximum value, and then drops back to the minimum value, forming a waveform. During this process, the solder joint will be subjected to constant voltage and current, and welding can be completed in a short time, resulting in higher quality solder joints.

The above is an introduction to the purpose and principle of resistance spot welding. We hope it can provide you with useful reference. This website will continuously update the knowledge and popularization of components and chips. Welcome to follow us.