Pre-precision welding technology is the world's the most advanced technology in large diameter spiral pipe production, also known as the two-step production. The principle is the first step in the pre-welding technology produced fine spiral welding, that is, on a three- roll strip molding machine while the first continuous weld (pre-welding) using a high speed gas shielded arc welding (MAG), after pre-carried out simultaneously with the welding plasma cutting machine will weld steel pre-cut into a predetermined length, and then transported to the pre-welded steel pipe more than fine welding production lines inside and outside the multi-wire submerged arc welding fine (second step). This approach from the traditional one-step spiral molding machine production speed must be bound and submerged arc welding speed synchronization, pre-welded fast making a pre-welding production line can also supply a number of fine welding production lines. Full use of their forming and welding characteristics achieve the combination of high speed and low speed welding molding, so that the production efficiency greatly improved. And because the pipe forming and submerged arc welding fine separately can solve the problem pipe forming and welding mutual interference. Both sides of the pre-weld pipe beveling relatively static, stable submerged arc welding fine quality, can avoid the traditional production of spiral weld prone to hot cracking, slag and other defects, but also eased the submerged arc weld bead camel-shaped, easy to get high-quality welds.
Pre-welding equipment including: welding power source, wire feed system, a dedicated high-current MAG welding torch, protective gas supply systems, automatic laser seam tracking system, 3D tracking torch torch clamping mechanism regulating skateboards and control systems.
The main role of the pre-welded steel pipe forming a tack welding, although it is the role of technology from positioning the weld when welding processes will all melt fine, the pre-forming and weld penetration depth of the weld process for submerged arc welding fine seam shaping and quality will have a huge impact. The spiral submerged arc welding especially in the pre-weld welding is carried out on the basis of pre-filled amount of weld groove,which will seriously affect the submerged arc welding quality control.