There are three common methods for forming welded steel pipes
1. Single radius forming method
The single-radius roll forming method has three methods: a circumferential bending forming method, an edge bending forming method, and a center bending forming method. The single radius forming method is: the hole type is composed of a single radius, and the forming machine horizontal roller and vertical roller are alternately arranged, and the strip is formed. From the middle of the horizontal roller and the vertical roller, the flat plate is gradually bent into a circular tube.
2. Circular bending forming method
The strip is bent and deformed at the same time in the whole width direction, and the bending radius of each frame is gradually reduced; the edge bending forming method starts from the edge of the strip, the bending radius is constant, and the deformation angle is gradually increased to reduce the middle portion of the strip. Width until the steel strip is rounded; the central bending method is to bend from the center of the strip, the bending radius is constant, and gradually expand to the side edges until it is closed.
3. Double radius forming method (comprehensive bending method)
Combination deformation is performed by using two or more basic deformation methods, but the edge molding method and circumferential molding method is used more. The forming method of the integrated deformation of the edge and the circumference of the tube blank, which bends the radius of the edge of the steel strip with the radius of the extrusion roll or the radius of the finished tube, and bends the edge of the steel strip to a certain deformation angle, and the forming frames remain substantially unchanged in the future. The bending of the middle portion of the strip is deformed and distributed according to the circumferential bending method. The molding process is stable, the deformation is uniform, the edge is relatively elongated, and the molding quality is good.