The steel coils are unfolded and leveled by the mill equipment. And they are sent to the forming machine in a certain angle. Supplemented by a certain angle, the continual pipes are formed in the principle of three-roll rolling machine. Continual spiral welding is welded by submerged-arc welding machine. When the uncoiling, coil detaching, leveling, steel cutting and welding are working, the host machine needs to stop and wait. After the steel welding finishing, the host machine starts to work again. The front-swing spiral welded pipe mill adopts intermittent production method with advantages such as low investment, and simple convenient.
The plate in certain width after slitting line and stripping is unfolded and leveled. Then, they are sent into forming machine. Used the roller, the plate is bent into pipe state. The edge of the steel plate is melted by making use of the proximity effect and skin effect of high frequency current. Then, the plate is extruded and welded into the pipe by extruding roller. Straight seam welded pipe mill also is called ERW mill.