High-frequency welding utilizes solid resistance heat as its energy source. It generates resistance heat within the workpiece through high-frequency current, heating the surface layer of the welding zone to a molten or nearly plastic state. Subsequently, upset forging force (applied or not) is exerted to achieve metallic bonding. It is a solid-phase resistance welding method widely used in the production lines of pipes and profiles.
1. Skin Effect
When an alternating current passes through a conductor, the current distribution across the conductor's cross-section is uneven. The current density gradually increases from the center of the conductor towards its surface, resulting in a physical phenomenon where most of the current flows along the conductor's surface. During high-frequency welding, the high-frequency current passes through the surface of the weldment, rapidly heating its outer layer.
2. Proximity Effect
When high-frequency currents flow in opposite directions in two conductors or in a reciprocal conductor, the currents concentrate on the adjacent sides of the conductors. In high-frequency welding, by controlling the position of the conductors, one can control the location and scope of the high-frequency current flow path, thereby achieving rapid localized heating of the weldment.
