High frequency welding effect on steel pipe

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


(1) Control the weld gap of the steel pipe, forming a welded steel pipe unit from the forming roller. After the guide roller is guided, it forms a circular gap steel pipe with an open gap. The extrusion amount of the squeezing roller is adjusted from 3mm to 3mm to keep the end of the weld line flat. The weld gap control is too large, the weld will be caused by poor fusion or cracking; the weld gap control is too small, due to overheating, resulting in weld burning, molten metal splashing, poor weld quality. under these circumstances,


2) The position of the induction coil should be placed on the same centerline as the steel tube. The distance between the front end of the induction coil and the centerline of the squeeze roller should not be burned. As close as possible. If the induction coil is away from the squeezing roller, the longer the effective heating time is, the wider the heat affected zone is, and the strength of the welding seam of the steel pipe decreases or does not penetrate, otherwise, the induction coil easily burns out the squeezing roller. under these circumstances,


3) Impedance impedance control of the resistance or a special set of magnetic rods, the impedance of the cross-sectional area should generally not be less than 70% of the cross-sectional area of the pipe diameter, its role is the induction coil, the pipe weld and the magnetic rod to form an electricity The magnetic induction cycle produces a proximity effect where the eddy current heat is concentrated at the edge of the pipe weld seam at the edge of the heating pipe. The resistance should be placed in the heating section in such a way that the front end is in the center of the squeeze roll, and the centerline is the centerline of the tube. Such as placing bad resistance, affecting the welding speed and welding quality, so that the steel pipe cracking.