Overview of cold processing of steel pipes; Characteristics and process flow of cold processing of steel pipes
Cold processing of steel pipes includes cold rolling, cold drawing, cold tension reduction, and spinning, which are the main methods for producing precision thin-walled, and high-strength pipes. Among them, cold rolling and cold drawing are commonly used cold processing and efficient production methods for steel pipes.
Compared with hot rolling, cold processing has the following advantages: It can produce large-diameter thin-walled pipes; High geometric dimensional accuracy; and High surface finish; It helps to refine the grains, and with the corresponding heat treatment system, it can obtain higher comprehensive mechanical properties: It can produce various special-shaped and variable-section materials and some materials with narrow hot processing temperature range, low high-temperature toughness and good room temperature plasticity. The outstanding advantage of cold rolling is its strong wall reduction ability. It can also significantly improve the performance, dimensional accuracy, and surface quality of the incoming materials. The pass reduction rate of cold drawing is lower than that of cold rolling, but the equipment is simpler, the tool cost is less, the production is flexible, and the shape and specification range of the product is also larger. Therefore, the site needs to reasonably combine cold rolling and cold drawing. In recent years, cold tension reduction, cold processing of welded pipes, and cold drawing of ultra-long pipes can increase the output of the unit. Expand the range of varieties and specifications, improve the quality of welds, and provide suitable pipe materials for cold rolling and cold drawing. In addition, warm processing has received much attention in recent years. Usually, induction heating to 200-400℃ is used to improve the plasticity of the tube blank. The maximum elongation of warm rolling is about 2-3 times that of cold rolling; the fracture shrinkage rate of warm drawing is increased by 30%. It is possible to obtain fine processing of some metals with low plasticity and high strength.
Although the specification range, dimensional accuracy, surface quality, and organizational properties of cold-processed pipes are better than those of hot rolling, there are four problems in its production: many cycles, long production cycles, large metal consumption, and complex intermediate processing. Figure 151 is a general process flow chart for cold rolling and cold drawing of carbon steel pipes and alloy steel pipes. Due to the different materials, technical conditions, and specifications of various steel pipes, their production process and process system are also different, but in general, they are composed of the following main processes:
1) Cold processing pre-treatment, including preparation of size, shape, structure, performance, and surface state;
2) Cold processing. This includes cold drawing, cold rolling, and spinning;
3) Finishing of finished products, including heat treatment, cutting, straightening, and inspection of finished products.
Post time: Oct-31-2024