Forming mode of welded steel pipe
Welded steel pipes, that is, slotted steel pipes, are formed by bending pipe blanks (steel plates and steel belts) into pipes with required cross-sectional shapes and sizes through various forming methods, and then welding the weld seams through different welding methods. The process of obtaining steel pipes. Compared with seamless steel pipe, welded steel pipe has higher product accuracy, especially wall thickness accuracy, simple main equipment, small floor space, continuous operation in production, flexible production and wide range of unit products. Welded pipes should be divided into three types according to production technology: spiral submerged arc welded pipes; Straight seam double-sided submerged arc welded pipe; Resistance welded pipe.
The production process of spiral steel pipe is roughly as follows
The raw materials of spiral steel pipe are strip steel coil, welding wire and flux.
Before forming, the steel strip is leveled, trimmed, surface cleaned and transported, and pre-bent.
The weld control device is used to ensure that the weld meets the welding requirements, and strictly control the pipe diameter, dislocation and weld.
After being cut into a single steel pipe, each batch of three steel pipes must go through a strict first-time inspection system to check the mechanical properties, chemical composition, fusion status of welds and surface quality of steel pipes, and ensure that the pipeline manufacturing process is qualified through nondestructive inspection. Before it can be officially put into production.
Longitudinal submerged arc welded pipe
Longitudinal submerged arc welded pipes are generally made of steel plates. After different forming processes, welded pipes are formed by double-sided submerged arc welding and post-welding expanding.
The main equipment includes milling machine, pre-bending machine, forming machine, pre-welding machine, pipe expander and so on. At the same time, there are many methods to shape LSAW pipeline, such as UO(UOE), RB(RBE), JCO(JCOE). Firstly, the steel plate is pressed into a U-shape, then into an O-shape, and then submerged arc welding is carried out internally and externally. After welding, the diameter (expansion) is usually called the terminal or full-length UOE welded pipe. It's a UO welded pipe. Bending the steel plate by roll bending, and then submerged arc welding is carried out internally and externally. After welding, the diameter is expanded to RBE welded pipe or not. The steel plates are formed in the order of J-type -C-type -O-type, and after welding, the diameter is expanded to JCOE welded pipe or not. Forming technology of UOE longitudinal submerged arc welded pipe.
The three main forming processes of UOE longitudinal submerged arc welding pipe include: steel plate pre-bending, U-shaped forming and O-shaped forming. Each process uses a special forming press to complete the following three processes: bending the edge of the steel plate in turn, and performing U-forming and O-forming in turn to deform the steel plate into a circular tube.
Forming technology of JCOE longitudinal submerged arc welded pipe. Forming: after multiple step stamping on JC0 forming machine, the upper half of the steel plate is pressed into a J shape, then the other half is pressed into a J shape to form a C shape, and finally the open "0" shaped tube is pressed from the middle.
Comparison of molding methods between JCO and UOE.
JCO forming is progressive pressure forming, which changes the forming process of steel pipe from two steps of UU forming to multiple steps. In the forming process, the steel plate is uniformly deformed, with small residual stress and no scratches on the surface. The processed steel pipe has greater flexibility within the size and specification range of diameter and wall thickness. It can produce a large number of products and small batches; It can produce large-diameter high-strength thick-walled steel pipes, as well as small-diameter and large-wall steel pipes. Especially in the production of high-grade thick-walled pipes, especially small and medium-diameter thick-walled pipes, it has incomparable advantages over other processes. As far as steel pipe specifications are concerned, it can meet more requirements of users. The investment is small, but the production efficiency is low, and the annual output is generally 100,000 tons to 250,000 tons.
Straight seam high frequency welded pipe
Straight-seam high-frequency welded pipe is formed by forming hot-rolled coil by forming machine. The skin effect and proximity effect of high frequency current are used to heat and melt the edge of tube blank, and pressure welding is carried out under the action of extrusion roller to realize production.
UOE molding adopts u and o double pressure molding. It is characterized by large capacity and high output. Suitable for mass production of single specification.
