Seamless pipe is a kind of steel pipe without welds, which is manufactured by hot processing methods such as perforation and hot rolling. When necessary, hot-processed tubes can be further cold-processed to the desired shape, size and properties. At present, seamless pipes are widely used in petrochemical production equipment.
According to different production methods, seamless pipes can be divided into cold-rolled pipes, hot-rolled pipes, extruded pipes, cold-drawn pipes, etc.: 1. Hot-rolled seamless steel pipes are generally produced on automatic pipe rolling units. After inspecting and removing surface defects, the solid tube blank is cut to the required length with the end face of the perforated end of the tube blank as the center, and then sent to the heating furnace for heating and perforated on the piercing machine. While piercing, continue to rotate and advance. Under the influence of the rollers and the end, the tube blank is gradually hollowed out, which is called a capillary tube. Then it is sent to the automatic pipe rolling machine for continuous rolling, and the sizing machine is used to determine the diameter, and the homogenizer is used to level the wall thickness to meet the specification requirements. 2. Use cold rolling, cold drawing or a combination of both. Seamless pipes of better quality and smaller sizes can be obtained. Cold rolling is usually performed on a two-high mill, where the steel pipe is rolled in an annular pass consisting of a fixed tapered plug and an annular groove of variable cross-section. 3. Extrusion method, that is, the heated tube blank is placed in a closed extrusion barrel, and the perforation rod moves together with the extrusion rod, so that the extrusion part is extruded from the smaller die hole. This method can produce smaller diameter seamless pipes.
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