Hot rolled seamless steel pipes are generally produced on automatic pipe rolling units. The solid tube blank is inspected and the surface defects are removed, cut into the required length, centered on the end face of the perforated end of the tube blank, then sent to a heating furnace for heating and perforated on the punching machine.
At the same time, the perforation is continuously rotated and advanced. Under the action of the roll and the head, a cavity is gradually formed inside the tube blank, which is called a capillary tube. It is sent to the automatic pipe mill for further rolling. Finally, the whole machine is uniform in wall thickness, and the sizing machine is sizing to meet the specification.
The production of hot-rolled seamless steel tubes by continuous rolling mills is a more advanced method. For smaller tubes of better size and better quality, cold rolling, cold drawing, or a combination of the two must be used. Cold rolling is usually carried out on a two-roll mill in which the steel pipe is rolled in an annular hole formed by a variable-section circular hole groove and a stationary tapered head. Cold drawing is usually carried out on a single-chain or double-chain cold drawing machine of 0.5 to 100T.
The extrusion process is to place the heated tube blank in a closed extrusion cylinder, and the perforated rod moves together with the extrusion rod to extrude the extrusion from the smaller die hole. This method can produce steel pipes with smaller diameters. Seamless steel pipe use: mainly used as a pipe or structural part for conveying fluid. The seamed steel pipe is mainly welded by steel plate (steel strip), so it is cheap and widely used.