Introduction to Forming Process of Spiral Welded Steel Pipe

　　The forming structure of spiral welded steel pipe is usually 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 steel 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 steel 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.

　　For example, when designing the structure of spiral welded steel pipe, we can use materials to process qualified pipe blanks under different rebound conditions, and control the maximum and minimum yield conditions to achieve the control of the rebound state of the pipe blank. The process design can be expressed by a complete mathematical model, so that each link can be presented more clearly.

　　At the same time, it also provides convenient management for on-site work management, and plays an important role in improving the forming quality of spiral welded steel pipe. In addition, for the preliminary design of spiral welded steel pipe forming process, it is necessary to modify the preliminary design according to the actual data of halving raw materials in the actual construction process, so as to improve the accuracy of the design results.