Submerged arc steel pipe forming methods include continuous twist forming (HME), roll forming method (CFE), Uing Oing Expanding forming method (UOE), roll bending forming method (RBE), Jing Cing Oing Expanding forming method (JCOE), etc. However, three forming methods, UOE, RBE, and JCOE, are widely used.

1. UOE forming method: UOE steel pipe unit forming process is divided into three steps to complete, namely pre-bending, U-shaped press forming, and O-shaped press forming, followed by cold expansion of the whole pipe to eliminate the pipe making process The resulting stress. The forming unit has huge equipment and high cost. Each set of forming equipment needs to be equipped with multiple casing inner and outer welders, which has high production efficiency. Due to the profiling, with more forming equipment, a steel pipe of one diameter needs a set of specific forming molds, and these molds need to be replaced when changing product specifications. The internal stress of the formed welded pipe is relatively large, and it is generally equipped with an expanding machine. The UOE unit has mature technology, a high level of automation, and reliable products, but the unit has a huge investment in equipment, which is suitable for the production of large-volume products.

2. RBE forming method: The stages of RBE forming are rolling, bending, and diameter expansion. The production process is mature. In the past, RB was mainly used to manufacture pressure vessels, structural steel, and water supply and drainage pipes with larger outer diameters and shorter lengths. Because ordinary enterprises cannot bear the huge investment of UOE pipe making unit, the RBE pipe making unit developed based on RB has the characteristics of small investment, moderate batch, convenient product specification, etc., so it has developed rapidly. The welded pipe produced by this forming process is close to the UOE steel pipe in terms of and performance, so it can replace the UOE welded pipe in most cases. The RBE pipe-making unit uses three-roll rolling to achieve steel pipe forming. The pipe-making process is that the three-roll forming machine rolls the steel plate into a steel pipe with a caliber, and then uses a forming roll to bend the edge of the steel pipe. , And then bend the edge with a forming roll or backbend. Because it is a three-roll continuous roll bending forming, the stress distribution generated during the steel pipe forming process is relatively uniform. However, when changing the product specifications, it is necessary to change the core roll and adjust the lower roll appropriately. A set of core rolls of the forming equipment can take into account the products of several specifications. The disadvantage is that the production scale is small, and the wall thickness and diameter of the steel pipe are greatly restricted due to the influence of the strength and rigidity of the core roller.

3. JCOE forming method: JCOE forming has three stages, that is, the steel plate is first pressed into a J shape, and then pressed into a C shape and an O shape in turn. E stands for diameter expansion. JCOE forming pipe-making unit is developed based on the UOE forming process. It learns from the working principle of U-shape and releases and implements the UOE forming process, which greatly reduces the tonnage of the forming machine and saves equipment investment. The steel pipe produced is the same as the UOE welded pipe, but the output is lower than the UOE welded pipe unit. This process is easy to realize automatic control in the forming process, and the product shape is better. JCOE forming equipment can be roughly divided into two forms, one is bending forming, the other is compression forming. Bending forming is mainly used in the forming process of thick and medium-thick plates, with smaller steps and lower output. The forming process is to roll the two edges of the steel plate into an arc on the bending machine according to the radius of curvature of the welded pipe, and then use the forming machine to press half of the steel plate into a C shape through multiple steps, and then start from the other side of the steel plate Pressing, after multiple stepping presses, the other side of the steel plate is also pressed into a C shape, so that the whole steel plate becomes an open O shape from the surface.