Perforation Method Of Seamless Steel Pipe
2021-12-14 14:53:44 COMMENT：0 HITS：
Seamless steel pipe production equipment: two roll cross rolling perforation process commonly used by piercer. The round tube blank is rolled into a hollow thick wall tube (rough tube), and the axes of the two rollers form an inclination angle with the rolling line.
In recent years, the inclination angle has increased from 6 ° ~ 12 ° to 13 ° ~ 17 °, which speeds up the perforation speed. For the production of steel pipes with a diameter of more than 250mm, secondary perforation shall be adopted to reduce the wall thickness of the capillary. New processes such as perforation with active rotating guide plate, perforation with rear thrust, axial discharge and cyclic top welding have also made some development, so as to strengthen the perforation process and improve the capillary quality.
The automatic pipe rolling machine rolls the thick wall rough pipe into thin wall blank pipe. Generally, it is rolled to the finished wall thickness after 2 ~ 3 passes, and the total elongation is about 1.8 ~ 2.2. Since the 1970s, the production efficiency has been improved and the mechanization of pipe rolling has been realized by using the technologies of single hole groove roll, double stand tandem mill, double groove tracking rolling and spherical plug.
The structure of the whole machine is similar to that of the piercer. The purpose of leveling is to eliminate the internal and external surface defects and the ovality of the waste pipe and reduce the uneven transverse wall thickness.
In recent years, the three roll homogenizer has been adopted to improve the deformation and homogenization efficiency of the homogenizer. The sizing machine is composed of 3 ~ 12 and the reducing machine is composed of 12 ~ 24. The reducing rate is about 3 ~ 28%.
The tension reducing mill, which appeared in the 1950s, controls the wall thickness with appropriate tension while adjusting the roll speed and reducing. The new tension reducing mill generally adopts three roll type, with 18 ~ 28 sets, the maximum reducing rate is 80%, the wall reducing rate is 44%, and the outlet speed is 18mm per second.
The tension reducing mill has the disadvantage of thickening at both ends, which can be eliminated by "sudden electrical control at the head and tail" or micro tension reducing.
There are four common series of automatic pipe rolling mill with outer diameter of 100mm, 140mm, 250mm and 400mm, producing steel pipes with outer diameter of 17 ~ 426mm.
The characteristics of the unit are that the main deformation is realized on the piercer, the specification change is flexible, and the range of production varieties is wide. Due to the development of continuous pipe rolling technology, units below 140mm are no longer built.
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