Introduction to Forming Process of Spiral Welded Pipe

　　Generally, the forming structure of spiral welded pipe is designed according to the forming parameters. In the forming process, the stress state should also be considered. After the strip steel is processed into spiral tube blank, the stress on the tube wall is mainly affected by the forming force during the strip steel forming process. According to the plastic deformation theory, when the relative bending radius of strip steel is equal to 100, the plastic deformation will be very obvious.

　　In the process of strip steel bending deformation, a large part will be converted into heat energy, which will lead to the temperature rise of spiral welded pipe. Only a small part of work will stay in the metal, forming residual stress in the metal. Among them, most of the energy stored in the metal is lattice distortion stress, which is mainly manifested in the deformation hardening of the pipe wall, and the tensile strength of the steel pipe will increase. At the same time, the inner layer metal and ten thousand layers of metal are subject to the pressure and tension respectively, which will produce reverse plastic deformation, and then Bauschinger effect will occur, leading to the decline of the yield strength of the strip steel.

　　At the same time, it is also necessary to reasonably design the forming process of spiral welded pipe, which usually adopts the springback control design. This can effectively control the springback state of the pipe blank, so as to ensure that the springback state of the pipe blank meets the design requirements. The yield strength of the material is the main factor affecting the springback state of the tube blank.