Welding method for welding steel pipe spirally

Abstract

The invention discloses a welding method for welding a steel pipe spirally. The welding method comprises the steps of: uncoiling a plate coil, flattening, milling edges, forming, welding and tracking detection. The welding method is characterized in that firstly the plate coil is uncoiled and flattened into a steel belt, and edge-milled into an X-shaped groove, the steel belt is conveyed to a spiral welded steel pipe former continuously according to the spiral angle; the formed steel-belt spiral steel pipe adopts a process with combination of internal and external submerged-arc welding and double-wire serial electric-arc and submerged-arc automatic welding, and then pre-internal welding, refined internal welding and external welding are carried out; a tracking sensor is adopted to detect the lowest point of a V-shaped groove of the formed seam at a distance before internal welding of the groove welded of the steel pipe to be welded to realize automatic tracking of refined welding and internal welding. The welding method disclosed by the invention has the advantages that the process with combination of internal and external submerged-arc welding and double-wire serial electric-arc and submerged-arc automatic welding and the tracking detection system is adopted, the welding deviation phenomenon and the fluctuation of welding offset can be avoided, the workload for correction and adjustment is reduced, the welding process is stable and reliable and the quality of the welding seam is ensured.

Description

technical field [0001] The invention relates to a method for manufacturing a seam welded steel pipe in which steel coils are spirally bent according to a certain curvature and then lapped along steel plates. Background technique [0002] The spiral welded steel pipe is formed by spiral coil welding of steel strips. The steel coils are spirally bent according to a certain radius of curvature and then welded together along the gaps of the steel plates. The spiral seams are welded by double-sided automatic submerged arc welding. In the production line of spiral welded steel pipe unit, the steel strip pulled out from the raw steel strip coil and leveled is driven by the steel strip delivery roller, and is continuously sent to the former according to the helix angle. Under the action of the wheel, the steel strip is bent and rolled into a spiral shape, and the welding torch head is always aligned with the spiral seam line for welding. [0003] Helical seam welding is achieved...

AI Technical Summary

Problems solved by technology

The current production method still has many problems in the production of high-strength, thick-walled spiral welded steel pipes, mainly in the following aspects: as the strength and wall thickness of the steel increase, the steel strip in the former, especially the belt on the delivery side Insufficient deformation of the steel edge. At the same time, the commonly used edge trimming process will also cause the phenomenon of underturning of the edge of the plate. When forming and occlusal, defects such as pouting, tight inside and loose outside of the forming seam, and wrong edges are prone to occur, which may even cause welding. Fatal defects such as micro-cracks in seams; problems such as crescent bends in the coil itself, which significantly affect the forming stability of the steel pipe, resulting in large changes in the circumference and ellipticity of the steel pipe, which cannot effectively ensure the stability of the outer dimension of the steel pipe. The on-site butt joint construction of steel pipes has a certain impact; in addition, with the increase of steel strength and wall thickness, the welding process becomes more difficult, and how to control the structure and performance of the weld is also a key problem that needs to be solved