Cold drawing method: after pretreatment, ordinary steel pipes are gradually reduced in diameter by cold drawing process, and then after several cold drawing processes, precision seamless steel pipes of various specifications are produced. This method mainly depends on physical deformation to change the shape and size of steel pipe, and does not involve chemical reaction, so it will not change the chemical composition of steel pipe.
Cold rolling method: for some steel pipes with high precision and high finish, cold rolling method can be used for production. After pretreatment, ordinary steel pipes are rolled on the cold rolling mill for many times, gradually reducing the diameter, improving the surface smoothness, and finally obtaining various specifications of precision seamless steel pipes.
Hot rolling method: For some precision seamless steel pipes with large diameter and high strength, hot rolling method can be used for production. After the billet is heated to a certain temperature, it is rolled many times on the hot rolling mill, gradually reducing the diameter and improving the uniformity of wall thickness. Finally, after cooling and straightening, various specifications of precision seamless steel pipes are obtained.
Extrusion method: For some precision seamless steel pipes with small diameter and high precision, extrusion method can be used for production. After the blank is heated to a certain temperature, it is extruded and deformed by the die on the extruder, gradually reducing the diameter and improving the surface smoothness, and finally obtaining various specifications of precision seamless steel pipes.
In the production of precision seamless steel pipe, the following points should be paid attention to:
Material control: the chemical composition and mechanical properties of raw materials have a vital impact on the quality of precision seamless steel pipes. Therefore, it is necessary to select raw materials that meet the requirements and carry out strict quality control.
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Production technology: Different production technologies are suitable for precision seamless steel pipes with different specifications and requirements. It is necessary to select the appropriate production process according to the specific needs and carry out fine process control.
Quality inspection: Precision seamless steel pipes require high dimensional accuracy and surface quality, so strict quality inspection is required. Common detection methods include eddy current detection, ultrasonic detection and optical detection.
For precision seamless steel pipes made of 20 #, 45 #, 10 #, 35 # and 40Cr, the manufacturing methods and precautions are slightly different. For example, 20# and 45# steels have good mechanical properties and machinability, and are suitable for manufacturing some parts with high requirements on strength and wear resistance; 10# steel has good plasticity and toughness, and is suitable for manufacturing some parts that need to bear large deformation. 35# and 40cr steels have good strength and hardness, and are suitable for manufacturing parts with high hardness requirements. Therefore, when selecting precision seamless steel pipes with different materials, it is necessary to choose according to specific application scenarios and requirements.
In a word, the production methods of precision seamless steel pipe mainly include cold drawing, cold rolling, hot rolling and extrusion. In the production process, we need to pay attention to material control, production technology, quality inspection and other issues to ensure that the product quality meets the requirements. At the same time, precision seamless steel pipes with different materials are suitable for different application scenarios and requirements, and need to be selected according to specific conditions.