7. What is high-frequency welded steel pipe?
It is a steel pipe made by welding metal materials (mainly steel plates) together using the resistive thermal effect of high-frequency current. This process uses the skin collection and proximity effects of high-frequency current to heat and melt the edge of the pipe billet, and pressure weld it under the action of an extrusion roller to achieve the production of steel pipes.
8. What is the principle of high-frequency welding?
High-frequency welding uses solid resistance heat as an energy source to heat the surface layer of the workpiece welding area to a molten or near-plastic state through the resistance heat generated by high-frequency current in the workpiece, and then applies (or not) top forging force to achieve metal bonding. It is a solid-phase resistance welding method that is widely used in the production line of tubes and profiles.
8.1. What is the skin effect?
When the conductor is subjected to AC current, the current distribution on the conductor section is uneven, the current density gradually increases from the center of the conductor to the surface, and most of the current flows only along the surface of the conductor. During high-frequency welding, high-frequency current passes through the surface of the weldment, causing the surface of the weldment to heat up quickly.
8.2. What is the proximity effect?
When a high-frequency current flows in opposite directions in two or reciprocating conductors, the current will be concentrated on the adjacent side of the conductor. In high-frequency welding, by controlling the position of the conductor, the position and range of the high-frequency current flow route can be controlled, so as to achieve local rapid heating of the weldment.
