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. Then, the final pipe is manufactured out after the IF annealing, fly-saw and sizing. Low pressure fluid straight seam HF welded pipe mill is mainly used to manufacture the low pressure fluid pipe, structure pipe and other pipe. Due to the low requirement on the pipe, the line normally does not have the welding seam IF annealing and whole pipe UT detector. Hydrotester also adopts low pressure one.
The forming styles of straight seam welded pipe can be divided into roll forming, flexible forming, full auto flexible forming. The mill developed by our company adopts roll forming when having small diameter （Φ≤114）. Flexible forming or full automatic flexible forming is adopted when having middle or large diameter（Φ≤711）.
In recent year, our company developed the precise control forming. The advantage of this kind forming is to guarantee the excellent forming quality in rough forming section through the precise control. Then it is no need to have the repair management in precise forming section. Therefore, the precise forming in this forming method does not need to change the roller. All the forming section does not need to change the roller, which solves the problem of the change in precise forming section and non-change in rough forming section. Therefore, it saves the roller investment and decreases the time of roller changing. Besides, during the diameter changing, all are controlled by industrial computer. The roller will automatically reach the position by inputting the pipe diameter, pipe wall thickness, material and other parameters. It largely improves the mill efficiency and pipe qualified rate. This forming method is suitable for medium and large mill from 219mm to 711mm, which saves the investment and improves the efficiency.
Loading Coil – Uncoiling – Leveling – Cutting And Coil Welding – Accumulator And Material Storage – Precise Leveling – Forming – High Frequency Welding – Water Cooling –Online UT Detector – Water Cooling – Sizing – Flying Cut Off – Pipe End Facing And Beveling Machine – Hydrotester –Pipe Collection