The production process of precision cold drawn steel pipes is a complex and delicate process, mainly including the following key steps:
1、 Raw material selection and preparation
Material selection: High quality carbon structural steel or alloy steel should be selected as raw materials, which should have good plasticity and processing performance to meet the requirements of cold drawing technology. At the same time, raw materials need to undergo strict chemical composition and physical property testing to ensure compliance with production standards.
Preprocessing: Pre treatment processes such as cutting, heating, and perforation of raw materials. The cutting process processes raw materials into suitable billet lengths; The heating process brings the raw material to the appropriate plastic deformation temperature; The perforation process uses a pressure perforating machine to pierce the heated round tube blank into a capillary tube, preparing for the subsequent rolling and cold drawing processes.
2、 Rolling and pickling
Rolling: Rolling the perforated tube to achieve the specified wall thickness and outer diameter of the steel pipe through the squeezing effect of the rolling mill. During the rolling process, it is necessary to strictly control the rolling temperature and speed to ensure the dimensional accuracy and surface quality of the steel pipe.
Pickling: The surface of the rolled steel pipe may be coated with oxide scale, oil stains, and impurities, and requires pickling treatment. Acid washing can remove these attachments on the surface of steel pipes, improve the cleanliness and smoothness of the steel pipe surface, and create favorable conditions for the subsequent cold drawing process.
3、 Cold drawing process
Cold drawing is the core process of precision cold drawn steel pipe production. At low temperatures, the steel pipe is continuously stretched through a mold to further reduce its size, improve its accuracy and surface smoothness. The cold drawing process requires strict control of factors such as stretching speed, mold size, and lubrication conditions to ensure that steel pipes do not break or deform during the stretching process.
Mold design: The design of cold drawing molds is crucial. The dimensional accuracy, surface smoothness, and hardness of the mold directly affect the quality of the finished cold drawn steel pipe. Therefore, mold design needs to be accurately calculated based on the specifications and requirements of the steel pipe, and suitable materials should be selected for manufacturing.
Lubrication treatment: In the cold drawing process, in order to reduce the frictional resistance between the steel pipe and the mold and improve the cold drawing efficiency, it is necessary to lubricate the steel pipe. Common lubricants include phosphates, resins, etc., which have good adhesion and lubrication properties.
Multi pass cold drawing: Due to the limited deformation of single pass cold drawing, in order to meet the dimensional accuracy requirements of precision cold drawn steel pipes, multi pass cold drawing technology is usually required. After each cold drawing process, the steel pipe needs to undergo intermediate annealing treatment to eliminate work hardening and improve its plastic deformation ability.
4、 Heat treatment and finishing
Heat treatment: Cold drawn steel pipes need to undergo heat treatment to eliminate internal stress, improve microstructure, and enhance mechanical properties. Common heat treatment methods include annealing, normalizing, etc.
Finishing: The process of straightening, cutting ends, and inspecting the heat-treated steel pipes. The straightening process can eliminate the bending and twisting phenomena of steel pipes during cold drawing and heat treatment; The head and tail cutting process can remove the irregular parts at both ends of the steel pipe; The inspection process comprehensively checks the dimensional accuracy, surface quality, and mechanical properties of the steel pipe to ensure that it meets customer requirements.
5、 Finished product inspection and packaging
Finished product inspection: Conduct finished product inspection on finished steel pipes, including appearance inspection, size measurement, mechanical performance testing, etc. Only steel pipes that meet customer requirements can be shipped as finished products.
Packaging: Packaging of steel pipes that have passed inspection to prevent damage during transportation and storage. Commonly used packaging materials include wood, foam, etc. These materials have good cushioning and fixing effects.
In summary, the production process of precision cold drawn steel pipes involves multiple links and complex process parameter control. By adopting advanced equipment and process methods, precision cold drawn steel pipes with high precision, high smoothness, and excellent mechanical properties can be produced to meet the needs of various high-end application fields.