1. Production process of straight seam high-frequency welded steel pipe
Straight seam welded steel pipe is made by rolling a long steel strip of a certain specification into a round tube through a high-frequency welding unit and welding the straight seam into a steel pipe. The shape of the steel pipe can be round, square or special-shaped, which depends on the sizing rolling after welding. The material of the welded steel pipe is mainly: low carbon steel
2. High-frequency welding
High-frequency welding is based on the principle of electromagnetic induction and the skin effect, proximity effect and eddy current thermal effect of AC charge in the conductor, so that the steel at the edge of the weld is locally heated to a molten state, and the butt weld is squeezed by the roller to achieve intercrystalline bonding, thereby achieving the purpose of weld welding. High-frequency welding is an induction welding (or pressure contact welding). It does not require weld filler, has no welding spatter, has a narrow welding heat-affected zone, beautiful welding shape, and good welding mechanical properties. Therefore, it is widely used in the production of steel pipes.
High-frequency welding of steel pipes utilizes the skin effect and proximity effect of alternating current. After roll forming, the steel (strip) forms a circular tube with a broken cross section. One or a group of resistors (magnetic bars) rotate near the center of the induction coil in the tube, and an electromagnetic induction loop is formed between the resistor and the opening of the tube. Under the action of the skin effect and the proximity effect, a strong and concentrated thermal effect is generated at the edge of the tube opening, so that the edge of the weld is quickly heated to the required welding temperature. After being squeezed by the pressure roller, the molten metal achieves intercrystalline bonding, and a strong butt weld is formed after cooling.
LSAW Carbon Steel tube
