Effect of high frequency welding on steel pipe

    In the process of high-frequency welding steel pipe, the welding process and the control of process parameters, the placement of the induction coil and the position of the resistor have a great influence on the welding quality of the steel pipe weld.

    1) Control of weld gap of steel pipe The steel strip enters into the welded pipe unit, which is formed by the forming roll, after the orientation of the guide roll, the round steel pipe blank with open gap is formed, and the squeezing amount of the squeezing roller is adjusted, ~ 3mm, and to keep the weld ends flush. Weld gap control is too large, will weld the weld caused by poor fusion or cracking; weld gap control is too small, due to excessive heat, resulting in weld burning, melting metal splash, welding quality of the weld . In this case,

    2) The position of the induction coil should be placed on the same center line as the steel tube. The distance between the front end of the induction coil and the center line of the squeeze roller should not be burned. As close as possible. If the induction coil is farther away from the squeeze roller, the effective heating time is longer and the heat-affected zone is wider, so that the strength of the steel pipe weld is decreased or not penetrated; otherwise, the induction coil is easy to burn the squeeze roller. In this case,

    3) The control of the impedance of the impedance of the resistor is a pipe or a group of special magnetic bar, the cross-sectional area of the impedance should normally not be less than 70% of the cross-sectional area of the tube diameter, its role is to induction coil, pipe welding edge and magnetic The rods form an electromagnetic induction loop, producing proximity effects, with vortex heat concentrated near the edge of the tube weld, which heats the edge of the tube to the welding temperature. The resistor should be placed in the V-zone heating section with the front end at the center of the squeeze roll so that the centerline coincides with the tube centerline. Such as the placement of the bad resistor, affecting the welding speed of welding and welding quality, so that steel pipe cracks.