Forming method of submerged arc steel pipe:
Submerged arc steel pipe forming methods include continuous twist forming (HME), row roll forming method (CFE), UingOingExpanding forming method (UOE), roll bending forming method (RBE), JingCingOingExpanding forming method (JCOE), etc., but the most widely used are UOE, RBE, JCOE three forming methods.
1. UOE forming method: The forming process of the UOE steel pipe unit is divided into three steps, namely pre-bending, U-press forming, and O-press forming, and then cold expansion of the whole pipe to eliminate the process of pipe making. generated stress. The forming unit has huge equipment and high cost. Each set of forming equipment needs to be equipped with multi-sleeve internal and external welding machines, and the production efficiency is high. Because it is imitation forming and there are many forming types of equipment, a set of specific forming dies is required for a steel pipe of one diameter. When changing product specifications, these dies need to be replaced. The internal stress of the formed welded pipe is relatively large, and a diameter expansion machine is generally equipped. UOE unit has mature technology, a high level of automation and reliable products, but the investment in unit equipment is huge, so it is suitable for the production of large batches of products.
2. RBE forming method: The stages of RBE forming are rolling, bending and diameter expansion and 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 large outer diameters and a short length. Because ordinary enterprises cannot afford the huge investment of UOE pipe-making units, the RBE pipe-making units developed based on RB have the characteristics of small investment, moderate batches, and convenient product specifications, so they have developed rapidly. The welded pipe produced by this forming process is close to the UOE steel pipe in performance, so it can replace UOE welded pipe in most cases. The RBE pipe-making unit is formed by three-roll rolling. The pipe-making process is that the three-roll forming machine rolls the steel plate into a steel pipe with a diameter of, and then bends its edges with forming rollers, and can also take back crimping. Since it is three-roll continuous roll bending, the stress distribution during the steel pipe forming process is relatively uniform, but when changing the product specification, the core role needs to be changed and the lower roll should be adjusted appropriately. A set of core rolls of the forming equipment can take into account several specifications of products. The disadvantage is that the production scale is small. Due to the influence of the strength and stiffness of the core role, the wall thickness and diameter of the steel pipe are greatly limited.
3. JCOE forming method: JCOE forming has three stages, that is, the steel plate is first pressed into J-shape, and then pressed into C-shape and O-shape in turn, E stands for diameter expansion. The JCOE forming tube-making unit is developed based on the UOE forming process. It draws on the working principle of the U-shape and releases and implements the UOE forming process, which greatly reduces the tonnage of the forming machine and saves the investment of the equipment. The produced steel pipe is the same as the UOE welded pipe, but the output is lower than that of the UOE welded pipe unit. This process is easy to realize automatic control in the forming process, and the product is formed well. JCOE forming equipment can be roughly divided into two forms, one is bending forming and the other is pressing forming. Bending forming is mainly used in the forming process of thick and medium plates, with small steps and low output. The forming process is to first roll the two edges of the steel plate into an arc shape according to the curvature radius of the welded pipe on the bending machine, and then use the forming machine to press half of the steel plate into a C shape through multiple-step stamping, and then start from the other side of the steel plate. Stamping, after several steps of stamping, the other side of the steel plate is also pressed into a C shape, and the entire steel plate is made into an open O shape from the surface.