Method of manufacturing seamless steel tubes
According to different production methods, it can be divided into hot rolled pipe, cold rolled pipe, cold drawn pipe, extrusion pipe and so on.
1.1. Hot rolled seamless tubes are generally produced on automatic tube rolling units. After checking and removing the surface defects, the solid tube billet is cut into the required length, centered on the end face of the perforated end of the tube billet, and then sent to the heating furnace for heating, and perforated on the punch machine. At the same time, the perforation continues to rotate and advance. Under the action of the roll and the head, the blank tube gradually forms a cavity, called capillary tube. Then it is sent to the automatic pipe rolling machine to continue rolling. Finally, the whole wall thickness of the whole machine is even, and the diameter is determined by the sizing machine to meet the specification requirements. It is an advanced method to produce hot rolled seamless steel pipe by continuous rolling mill.
1.2. To obtain smaller size and better quality seamless tubes, cold rolling, cold drawing or a combination of both must be used. Cold rolling is usually carried out on a two-high mill in which the steel pipe is rolled in a circular pass consisting of a circular groove of variable section and a fixed conical head. Cold drawing is usually carried out on 0.5 ~ 100T single or double chain cold drawing machine.
1.3. The extrusion method is to put the heated tube blank in the closed extrusion cylinder, and the perforation rod and the extrusion rod move together to extrude the extruded parts from the smaller die holes. This method can produce steel pipe with smaller diameter.