In the process technology, our country is equipped with advanced seamless steel tube production line, most of which were built after 1990. The advanced technologies such as computer control, cone piercing machine, roll full hydraulic pressure technology, centralized variable roll design, roll single drive,Stainless Steel Tube Mills rolling of limited-moving mandrel, rolling of step mandrel and so on, are widely used in production process. With the continuous progress of technology and equipment level of seamless steel tube industry in China, stainless steel pipe (including large diameter, thick wall) mode of production has also diversified development, mainly extrusion units, Cycle tube mill units, pipe units, piercing (piercing + cold rolling, cold), hot rolling + cold rolling,Stainless Steel Tube Mills cold drawing and other methods of production. In addition, there are also a small number of other methods of production, such as forging boring methods.
Hot extrusion process is one of the production processes of seamless stainless steel pipe in foreign countries. Compared with the rolling production method, the characteristic of extrusion is that the metal is subjected to three-dimensional compressive stress in the process of deformation, and in this optimum condition, it can obtain better inner and outer surface quality and metallographic microstructure for the high-end stainless steel pipe with large deformation resistance and thermal plasticity, and is suitable for producing small batch and multi specification stainless steel pipe. It is especially suitable for producing high alloy pipes which are difficult to be machined by inclined rolling mills.
Although the production of stainless steel pipe in China adopts "piercing + cold drawing, cold rolling" process is more, but the advantages of using extrusion method to produce stainless steel pipe can be directly used as raw materials, product quality is relatively stable,Stainless Steel Tube Mills the replacement of flexible varieties, can directly produce hot extrusion finished pipe, can also produce a variety of profiled stainless steel pipe. The production of large diameter (thick wall) stainless steel pipe In addition to a small number of "perforation + Pilger rolling" process (including the top tube unit), basically using hot extrusion process.
With the application of high speed, automation and large tonnage extruder, the development of the related technologies, such as high strength, high toughness and heat-making mould, the production of stainless steel pipe by extrusion method or the supply of waste pipe for cold processing is a better and economical method for the hot-working stainless steel pipe at present. In particular,Stainless Steel Tube Mills the production of difficult deformation of stainless steel pipe, high alloy steel pipe, thick wall tube has been rapidly developed.
At present, the world's cold rolling and cold drawing technology and equipment level has a great development. Cold rolling mill, cold drawing machine forward to high-speed, high-precision, long travel, multi-line direction development, can achieve large reduction and large wall reduction, rolling deformation of about 80% in the cold rolling mill. Adopt cold-rolled fixing wall, auxiliary to change specification and control outside diameter to meet the requirements of different varieties and specifications. The process characteristic of this kind of rolling mill is:
1 The inertia force and the inertia torque vertical balance mechanism are adopted, and the rolling mill is improved.
2) Adopting ring hole type, length is 70% longer than short trip mill,Stainless Steel Tube Mills the uniformity of rolling deformation is increased and the feed quantity increases.
3 Using long tube billet, increase the length of the pipe, can produce super long steel pipe, increase the mill productivity, improve the effective utilization coefficient of rolling;