Processing process of thermal expansion straight seam steel pipe

The straight seam steel pipe is completed on the high frequency welded pipe machine, and generally consists of rolling forming, kneading, sizing, flying saw plugging, etc. The front end of the unit is equipped with a material storage ring, and the rear end is equipped with a steel pipe turning frame. The shape of the straight seam steel pipe can be Round, square or special-shaped, it depends on the rolling diameter after welding. The electrical part should not be composed of high-frequency generator, DC excitation generator and external automatic control equipment. The material of thermal expansion steel pipe is not required to adopt σs≤300N/ mm2, σs≤500N/mm2 low-alloy steel, low-carbon steel or other steel materials, thermal expansion straight seam steel pipe is a kind of straight seam steel pipe, the following will introduce how the thermal expansion straight seam steel pipe is processed.

Thermal expansion straight seam steel pipe is based on the principle of electromagnetic induction, combined with the proximity effect in the conductor, the eddy current heat effect and the skin effect of the AC charge, the steel at the edge of the weld is heated into a molten state, and the butt weld is directly closed after being kneaded by a roll. .
Processing Technology of Heat Expansion Straight Seam Steel Pipe
Generally speaking, the base material of the heat-expanded steel pipe is made of straight seam and small diameter, and the heat-expanded straight-seam steel pipe is expanded in the radial direction by the sector block at the end of the expander, so that the entire pipe section gradually undergoes plastic deformation.
The inner diameter of the heat-expanded straight seam steel pipe is processed, and the base of the fan starts to reduce the movement speed of the front section until it reaches the required position, that is, the circumferential position of the finished pipe, and reaches the required quality; the elastic compensation process of the heat-expanded straight seam steel pipe, at the position of the sector block It will be further reduced until it reaches the required position, that is, the circumferential position before the rebound of the heat-expanded straight-seam steel pipe; the pressure-holding and stable processing of the heat-expanded straight-seam steel pipe does not change the circumferential position of the fan block, which is the result of the equipment and the bulging process during the recovery process. The pressure-holding and stabilization stage required for a period of time before the bombing; the unloading and return treatment of the thermal expansion straight seam steel pipe, the fan-shaped block shrinks rapidly from the circumferential position of the thermal expansion straight seam steel pipe until it reaches the initial position, this is in the elastic recovery Before, that is, the expansion process of the smaller shrinkage diameter of the required fan-shaped block; for the full-circle processing of the heat-expanded straight seam steel pipe, the fan-shaped block is opened until the fan-shaped block contacts the inner wall of the heat-expanded straight-seam steel pipe. At this time, the heat-expanded straight seam steel pipe is in the The radius of each point within the step size range is basically the same, and the thermally expanded straight seam steel pipe forms an initial circle.

Surface treatment method of straight seam steel pipe
The cleaning of straight seam steel pipes uses solvents to clean the steel surface to remove oil, grease, dust, lubricants, etc., but it cannot remove scale, rust and flux on the steel surface. It can only be used as an auxiliary means for anti-corrosion production. If the steel surface is firm Attached iron scale, the derusting effect is not ideal, and cannot meet the requirements of anti-corrosion construction for anchor particles. Straight seam steel pipe derusting tools mainly use wire brushes and other tools to polish the steel surface. Manual derusting can reach SA2 level, and electric tools can reach SA3 level, can clean loose or raised scale, rust and welding slag, the pickling of straight seam steel pipes is generally treated by chemical and electrolytic methods, and can be used as reprocessing after sandblasting and rust removal, although chemical cleaning can make the surface It is clean and rough, but its anchor particles are shallow and easy to pollute the environment. Chemical pickling can only be used for pipeline anticorrosion, and can remove scale, rust and old coatings