Small-caliber cold drawn seamless steel pipe is a round, square and rectangular steel with a hollow section and no joints on the periphery. Seamless steel pipes are made of steel ingots or solid tube billets through perforation into capillary tubes, and then made by hot rolling, cold rolling or cold drawing. Seamless steel pipes have a hollow section and are mostly used as pipelines for conveying fluids. Compared with solid steel such as round steel, steel pipes have the same bending and torsion strength and lighter weight. They are economical cross-section steels and are widely used in manufacturing structures. Parts and mechanical parts, such as oil drill pipes, automobile transmission shafts, bicycle frames, and steel scaffolding used in construction.

 

According to different production methods, it can be divided into hot-rolled tubes, cold-rolled tubes, cold-drawn tubes, extruded tubes, etc. Hot-rolled seamless tubes are generally produced on automatic tube rolling mills.

 

The solid tube is inspected and removed from surface defects and cut to the required length. The tube is centered on the perforated end face of the tube and then sent to the heating furnace for heating. The piercing machine is pierced while continuously rotating and advancing. Under the action of the roller and the top head, The inside of the tube billet gradually forms a cavity called capillary, and then it is sent to the automatic tube rolling mill to continue rolling. Finally, the wall thickness is uniformed by the equalizer, and the diameter is sizing by the sizing (reducing) machine to meet the specification requirements. The continuous tube rolling mill is used to produce Hot-rolled seamless steel pipes are more advanced methods. If you want to obtain seamless pipes of smaller size and better quality, you must use cold-rolled and cold-drawn or a combination of the two methods. Cold rolling is usually carried out on a two-roll mill. Rolling in the annular pass formed by the variable cross-section circular hole groove and the immovable tapered plug. The cold drawing is usually carried out on the single-chain or double-chain cold drawing machine. The heated tube is placed in a sealed The perforated rod in the extruded cylinder moves together with the extruded rod, so that the extruded part is extruded from a smaller die hole. This method can produce steel pipes with a smaller diameter.