The manufacturing method of seamless steel pipes

1.1 Hot rolled seamless pipes are generally produced on automatic pipe rolling mills. The solid tube blank is inspected and surface defects are removed, cut into the required length, centered on the end face of the tube blank perforation end, and then sent to the heating furnace for heating, and perforated on the perforation machine. During perforation, continuous rotation and advancement occur, and under the action of the rolling mill and the top, a cavity gradually forms inside the billet, known as a capillary. Then it is sent to the automatic pipe rolling machine to continue rolling. Finally, the entire machine was uniformly adjusted for wall thickness, and the diameter was determined by a sizing machine to meet the specification requirements. The use of continuous pipe rolling mills to produce hot-rolled seamless steel pipes is a more advanced method.
1.2. To obtain seamless pipes with smaller dimensions and better quality, cold rolling, cold drawing, or a combination of both methods must be used. Cold rolling is usually carried out on a two roll rolling mill, where steel pipes are rolled in a circular pass formed by a variable cross-section circular groove and a fixed conical head. Cold drawing is usually carried out on single chain or double chain cold drawing machines with a capacity of 0.5-100T.
1.3. The extrusion method involves placing the heated tube blank in a closed extrusion cylinder, and the perforated rod moves together with the extrusion rod to extrude the extruded part from the smaller mold hole. This method can produce steel pipes with smaller diameters.