The spiral steel pipe will send the strip steel to the welded pipe unit, and the strip steel will gradually roll up after rolling by multiple rollers to form a circular tube blank with an opening gap. Adjust the reduction of the extrusion roller so that the weld gap is controlled at 1-3mm and the two ends of the welded joint are flush.
1. If the gap is too large, the proximity effect will be reduced, the eddy current heat will be insufficient, and the poor intergranular joint of the weld will result in incomplete fusion or cracking.
2. If the gap is too small, the proximity effect will increase, the welding heat will be too large, which will cause the weld to burn; or the weld will form a deep pit after extrusion and rolling, which will affect the weld surface quality.
After heating the two edges of the tube blank to the welding temperature, under the extrusion of the extrusion roller, the common metal grains infiltrate and crystallize with each other, finally forming a solid weld. If the extrusion pressure of spiral steel pipe is too small, the number of common crystals will be small, the strength of weld metal will decline, and cracks will occur after the stress; if the extrusion pressure is too large, the molten metal will be extruded out of the weld, which not only reduces the strength of the weld, but also produces a large number of internal and external burrs, and even causes defects such as weld overlap.
Main process features of spiral steel pipe:
1. During the forming process, the steel plate has uniform deformation, small residual stress and no scratch on the surface. The processed spiral steel pipe has greater flexibility in the size and specification range of diameter and wall thickness, especially in the production of high-grade thick wall steel pipe, especially in the small and medium-sized thick wall steel pipe, which has advantages that other processes can not match, and can meet more requirements of users in the specification of spiral steel pipe.
2. The advanced double-sided submerged arc welding technology can realize welding in a good position, and it is not easy to have defects such as wrong edge, welding deviation and incomplete penetration, and easy to control the welding quality.
3. Conduct 100% quality inspection on steel pipes, so that the whole process of steel pipe production is under effective detection and monitoring, and effectively ensure the product quality.
4. All equipment of the whole production line has the function of networking with the computer data acquisition system to realize the real-time data transmission, and the intermediate control room is responsible for the technical parameters in the production process.