The back swing type spiral welded pipe unit is to open and level the steel coil through the unit equipment, and then send it to the forming machine at a certain angle, using the principle of three roll coiler, supplemented by a certain angle, to form a continuous round pipe, and the continuous spiral weld is welded by submerged arc welding machine. The uncoiled, uncoiled, leveled and sheared butt welding of steel coil are all carried out on the reciprocating flying welding car. When butt welding of steel coil is carried out, the flying welding car keeps the same speed with the main machine, and the main machine does not stop for continuous production. When butt welding is completed, the flying welding car quickly retreats to the initial position and waits for the next steel coil. This kind of continuous production mode has the advantages of high production efficiency, good product quality and few repair welded pipes. According to the different uses of products, the rear swing spiral welded pipe unit is divided into: API standard model, national standard model. API standard model is mainly used for the production of oil and natural gas (long-distance) transmission pipes. It has very high requirements for the material and quality of steel pipes, as well as for the unit equipment and inspection equipment. The national standard model is mainly used for short-distance natural gas transmission and water delivery pipe, urban pipe network construction, structural pipe, column pipe, etc. The steel material and quality requirements are also high, second only to API standards.

coil uncoiler→pinching&leveling→electric vertical roll→hydaulic cut head&tail →buttwelding→electric vertical roll→edge mill device→board surface cleaner→ manul vertical rol→ main feeding &delivery→pre-bending&guide board→forming→inside welding→outside welding→plasma cutting→pulling out→ finished product inspection→collecting 

1.Forming machine automatic adjustment system : This mill adopts the database + computer automatic control technology to adjust the machine when it changes the specification. This mill needs to adjust the angle of the front axle, the Angle of the six-component roller of the forming machine, the position of the six sets of rollers of the forming machine and the angle of the welding pad roller when changing the specifications. In the past, the adjustment work of the mill was completed by experienced adjustment workers, basically relying on the experience of adjustment workers, which is easy to cause a single adjustment is not in place, repeated adjustment, thus more waste pipes, and the adjustment workload is large, very cumbersome. This set of front axle and molding machine need to adjust the Angle and position precisely controlled by the encoder, and to advance according to the theory of data, the establishment of a complete database, in the production of some specifications of the steel tube, just on the computer tablet parameters such as width, diameter, wall thickness, all adjust parts will come to the right place, start production directly. This reduces the need for adjustment, the reliance on experienced adjusters, and the waste pipe.

2.B.Uncoiler automatic centering function：There is the centering button on the operation stand of uncoiler. When the button is switched on, the double cone heads will automatically centralize the mill centerline. Then, the coil center is consistent to the mill center. It is no need to adjust with the vertical rollers. The production efficiency is improved and the instability is decreased.