Discussion on the Welding of Convex Nuts

Convex nuts are widely used in industries such as automotive and hardware appliances. Due to their high strength and sealing characteristics after welding, they are particularly suitable for applications that require high quality and strength, such as heavy-load body bolts, nuts, and joints and end caps that seal oil and water.

Equipment Requirements for Convex Welding

The welding of convex nuts requires significant equipment power because the welding of convex points is calculated based on the current required per unit volume. For example, the current required for welding carbon steel convex points is approximately 3-5KA/mm³. In contrast, the volume of convex welding is usually much larger, meaning the required current can reach several tens of KA. Consequently, the power of the matching equipment is also quite high, with medium-frequency сварка equipment typically having a power rating above 250KV and energy storage welding machine exceeding 20000J.

Welding current is directly proportional to welding pressure; thus, the large welding current necessitates substantial welding pressure. Therefore, the pressure mechanism of convex welding equipment is generally quite large, with cylinder diameters often exceeding ¢200 and output pressures above 15KN.

Specific Application Scenarios

In the automotive industry, the specifications for convex nuts and bolts range from M6 to M12, with convex diameters typically between ¢10 and ¢25. The materials of the plates connected to these nuts include low-carbon steel, high-strength steel, and hot-formed steel. The strength after convex welding can reach the point of tearing or pulling through the base material, with thrust strengths ranging from 8KN to 30KN.

In exhaust systems, stainless steel convex nuts can have diameters exceeding ¢30, requiring equipment power of up to 920KVA to meet welding demands. Another application scenario is the oil pan nuts, which require sealing; therefore, the equipment selected is often large energy storage welders.

In the home appliance industry, the application of convex welding primarily focuses on water inlet welding, with convex diameters usually greater than ¢20. The welding materials include stainless steel and low-carbon steel. Due to the relatively thin materials, the destructive testing after welding requires tearing through a ring of the base material to be considered qualified. Convex welding ensures both strength and effective sealing.

Процесс сварки

Convex welding still falls under the category of projection welding and requires strict welding specifications, namely high current and high pressure. Compared to ordinary projection welding, the volume of convex welding is larger, resulting in a slightly longer required welding time, especially when using medium-frequency direct current welding, where welding times can reach 120-200 milliseconds. If using a capacitor discharge welder, the welding time does not need to be a major concern; instead, focus on selecting a larger welding current and pressure.

In sealing-required scenarios, it is crucial to avoid large sparks during the welding process to prevent spatter from causing welding defects and leaks. This necessitates greater welding pressure and better responsiveness. The pressure spindle should use a diamond heavy-duty structure to ensure that no deformation or misalignment occurs under high pressure, thereby ensuring uniform melting around the convex area during welding.

Заключение

The welding of convex nuts plays a significant role across various industries, and the choice of welding technology and equipment directly impacts welding quality and product performance. Understanding the key factors and application scenarios of welding can help optimize welding processes and improve production efficiency.