Effect of Current on Spot Welding Heating

Resistance welding is widely used in the electronics and automotive industries. We need to use spot welding technology and equipment in the processing of some metal workpieces. And there are many factors affecting the welding quality, such as: 1. Welding current or voltage, power; 2. Welding time; 3. Shape and specification of welding materials; 4. Information and thickness of electroplating on the surface of welding materials; 6. Electrode material and tip diameter; 7. Selection of welding power source and pressurizing machine head. The following focuses on the impact of spot welding heating.

The external condition of forming internal heat source-resistance heat is welding current, and the influence of resistance and time on heat evolution is smaller than that of current, mainly through the following two ways to exert influence on the heating process of spot welding.

The change value of the evolution heat of the internal heat source depends on the effective value of the welding current, and the heating process is affected by it. In addition, the heating effect is also related to the characteristics of the current waveform when the thin piece spot welding is carried out. According to the thermal time constant definition, when the low carbon steel is spot welded below 0.4mm+ below 0.4mm, The application of current pulse amplitude is easier to characterize the heating effect than the effective value of the applicable power frequency alternating current.

Welding current on the internal resistance of the weldment (average) generated by the current situations of distribution, will lead to each local heating intensity uneven weld zone, which affects the heating process of the spot welding, spot welding current field and current throughout have characteristics as follows: the current line in two welding joint surfaces to form concentrated contraction, the result will make joint surface formed centralized heating effect. The peak current density appears at the edge of the lamination surface, where the heating intensity is high, so the plastic connection zone will appear first, which can ensure the normal growth of the fused core.

Characteristics of spot welding current field, make its heating for the uneven heat process, the welding temperature at various points in the area, which forms the uneven temperature field, based on choosing different welding current waveform, changing the style of electrode surface size, etc., can change the current field form throughout, and control the current density to achieve the goal of control molten nuclear style and position.

Zhuzhou Weilai focuses on the research and development of resistance welding electrodes and has established an "industry-university-research" cooperation system with the Powder Metallurgy Attitude of Central South University, with several patented technologies to help enterprises improve production efficiency and optimize product quality.