Seamless Black Steel Pipe Production Process

According to the different production methods, the production process of seamless black steel pipe can be divided into hot rolled pipe, cold rolled pipe, cold drawn pipe and extruded pipe.

1. Hot-rolled seamless pipes are generally produced on automatic rolling mills. The solid tube blank is inspected and surface defects are removed, cut to the required length, centered on the end face of the perforated end of the tube blank, and then sent to a heating furnace for heating and punching on a punch. At the same time, the perforation keeps rotating and advancing. Under the action of the roll and the head, a cavity is gradually formed inside the tube blank, which is called a capillary. It is sent to the automatic tube mill for further rolling. Finally, the wall thickness of the whole machine is uniform, and the sizing machine reaches the specifications. It is a relatively advanced method to produce hot-rolled seamless steel pipes with continuous rolling mills.

2. In order to obtain seamless pipes with smaller size and better quality, cold rolling, cold drawing or a combination of both must be used. Cold rolling is usually carried out on a twin-roll mill, and the steel pipe is rolled in an annular hole formed by a variable-section circular hole groove and a fixed cone head. Cold drawing is usually carried out on a single-chain or double-chain cold drawing machine of 0.5 to 100T.

3. The extrusion method is to place the tube blank to be heated in a closed extrusion cylinder, and the perforated rod and the extrusion rod move together to extrude the extrusion part from the smaller die hole. This method can produce steel pipes with smaller diameters.

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