First, the production method of seamless steel pipe:
Hot rolled seamless steel pipe
Hot rolled seamless pipes are generally produced on automatic rolling mills. The solid tube blank is inspected and the surface defects are removed, cut into the required length, centered on the end face of the tube blank, and then sent to the furnace for heating and perforated on the punch. At the same time, the perforation is continuously rotated and advanced. Under the action of the roll and the head, a cavity is gradually formed inside the tube blank, which is called a capillary tube. It is sent to the automatic rolling mill for inherited rolling. Finally, the whole machine is uniform in wall thickness, and the sizing machine is sizing to meet the specification. The use of continuous rolling mills to produce hot-rolled seamless steel tubes is a way to improve their predecessors.
2. Cold rolling, cold drawing
In order to obtain seamless pipes of smaller size and better quality, it is necessary to use cold rolling, cold drawing or a combination of the two. Cold rolling is usually carried out in a two-roll mill, and the steel pipe is rolled in an annular hole type composed of a variable-section circular hole groove and a stationary tapered head. Cold drawing is usually carried out at a single-chain or double-chain cold drawing machine length of 0.5 to 100T.
3. Extrusion method
The extrusion process is to place the heated tube blank in a closed extrusion cylinder, and the perforated rod moves together with the extrusion rod to extrude the extrusion from the smaller die hole. This method can produce steel pipe with small diameter. The seamless steel pipe is a long steel with a hollow section and no joints around.
Second, the application range of seamless steel pipe:
Seamless steel tubes have a hollow section and can be used as a conduit for transporting fluids, such as pipelines for transporting petroleum, natural gas, gas, water and certain solid materials. Compared with solid steel such as round steel, seamless steel pipe has light weight when it has the same bending and torsional strength. It is an economical section steel and is widely used in the manufacture of structural parts and mechanical parts, such as oil drill pipes and automobile transmission shafts. , bicycle racks and steel scaffolding used in construction. The use of seamless steel tubes to manufacture ring-shaped parts can improve material utilization, simplify manufacturing processes, save materials and processing man-hours, such as rolling bearing rings, jack sleeves, etc., and have been widely used in steel pipes. Steel pipes are also indispensable materials for various conventional weapons, and barrels, barrels, etc. are all made of steel pipes.
1. Structural seamless steel pipe (GB/T8162-2008) is a seamless steel pipe for general structural and mechanical structures.
2. Seamless steel pipe for fluid transportation (GB/T8163-2008) is a general seamless steel pipe for conveying fluids such as water, oil and gas.
3. Low- and medium-pressure boiler seamless steel pipe (GB3087-1999) is used to manufacture various structures of low and medium pressure boilers.
Steel pipes can be divided into round pipes and shaped pipes according to the shape of the cross-sectional area. Since the area of the circle is the largest under the condition of equal circumference, more fluid can be transported by the circular tube. In addition, the circular section is subjected to a relatively uniform force when subjected to internal or external radial pressure, and therefore, most of the steel pipes are round pipes. However, the round pipe also has certain limitations. For example, under the condition of being bent by the plane, the round pipe is not as strong as the square and rectangular pipe, and some agricultural machinery skeletons, steel wood furniture, etc. are commonly used for square and rectangular pipes. Shaped steel pipes of other cross-section shapes are also required depending on the application.