Description
Precision steel pipe is a kind of high-precision steel pipe material after cold drawing or hot rolling. Due to the advantages of no oxide layer on the inner and outer walls of precision steel pipe, no leakage under high pressure, high precision, high finish, no deformation in cold bending, flaring, flattening and no cracks, it is mainly used to produce products of pneumatic or hydraulic components, such as air cylinder or oil cylinder, which can be seamless pipe or welded pipe.The cold working methods of steel pipe mainly include cold drawing and cold rolling. In recent years, with the development of science and technology, a cold spinning method has been developed. This method can produce large-diameter and high-precision cold-rolled tubes and variable section cold-rolled tubes. The raw material of cold-worked steel pipe can be hot-rolled seamless steel pipe or welded pipe. The common characteristics of steel pipe cold working method are high dimensional accuracy and good surface roughness. It can produce very thin (up to 0.05 ~ 0.01mm) thin-walled tubes and very thin (up to 0.3 ~ 0.1mm) capillaries. High precision cold drawn precision steel pipe is a new type of steel pipe, which is mainly characterized by high precision. There are usually two production processes of two high mill and three high mill. The precision of three high mill in producing cold rolled seamless steel pipe is higher, which can be controlled within a few wires, but the price is relatively higher The popularization and application of high-precision cold drawn precision steel pipe can save steel, improve processing efficiency and save energy. The so-called high-precision cold drawn seamless steel pipe refers to the strict dimensional accuracy (tolerance range) of inner and outer diameter, and good internal and external surface finish, roundness and straightness, which can greatly save machining hours, improve material utilization and improve product quality. The main advantage of cold rolled steel pipe is large section reduction rate, especially strong wall reduction ability. For carbon steel, the section reduction rate of one-time rolling can reach 80% ~ 83%, and that of alloy steel can reach 72% ~ 75%. Its main disadvantage is that it is difficult to replace tools. In addition to being directly used to produce some cold rolled tubes with high precision, cold rolling method is often used in combination with cold drawing method to open billets for cold drawing. This can not only give full play to the wall reduction ability of cold rolling, but also skillfully make use of the advantages of easy replacement of cold drawing tools, which is conducive to improving productivity, expanding product production range and improving steel pipe surface quality. At present, the production of cold-rolled pipe is mainly based on the periodic cold-rolled pipe mill. The working feature of the periodic cold rolling mill is that the steel pipe and mandrel do not move. The rolling mill is driven by the reciprocating motion of the frame to roll the steel pipe back and forth, and the rolled piece is compressed by the variable section pass, so as to achieve the purpose of reducing diameter and wall.