Production of various precision bright tubes
Precision pipe is a kind of seamless steel pipe with high precision and high brightness produced by cold drawing or cold rolling process. Its internal and external diameter can be accurate to within 0.2mm. It not only ensures the bending and torsional strength, but also has light weight. Therefore, it is widely used in the manufacture of precision mechanical parts and engineering structures. It is also commonly used in the production of various conventional weapons, barrel, shell, bearing, etc.
Common materials are 10#, 20#, 35#, 45#, 20Cr, 40Cr, 20CrMo, 16Mn, 27SiMn, 304, 201, 310S, high-quality carbon structural steel.
1. Smaller outer diameter.
2. High precision and can be used for small batch production.
3. Cold drawn products have high precision and good surface quality.
4. The cross area of steel pipe is more complex.
5. The steel pipe has superior performance and dense metal. The inspection method can use soapy water to wipe the joints of the annealing furnace to see whether there is air leakage; Among them, the place where gas is most likely to escape is the place where the annealing furnace enters and exits the pipe. The sealing ring in this place is particularly easy to wear, so it should be checked and replaced frequently. The process scheme of pretreatment of precision steel pipe before cold bending is put forward; The effects of normalizing temperature, holding time and cooling mode on the microstructure and mechanical properties of feed pipe were studied and analyzed; The conventional normalizing process of precision steel pipe is determined: heating temperature is (890 ± 10) ℃, and scattered air cooling after holding for 6min. Conventional normalizing process can completely eliminate the widmanstatten structure of precision steel pipe, make the matching of yield strength and tensile strength more reasonable, and improve the yield strength ratio σ S/b σ ≤ 0.78, elongation 5 δ ≥ 30%, greatly improve the cold forming performance and avoid cold bending cracking. The coefficient of expansion can be expressed in volume or length, usually in length. Density the density of a substance is the mass per unit volume of the substance, in kg / m3 or 1B / in3. The residual tensile stress mainly comes from the residual tensile stress produced by the equipment during welding.
At present, annealing after welding cooling is widely used in engineering to eliminate residual stress, and post welding cooling is an important process of residual stress generation. This method not only wastes energy, but also easily produces large welding residual stress. Post weld heat treatment is a new technology to eliminate residual stress. The precision steel pipe shall be preheated to the post heat treatment temperature before welding, and the weldment shall be continuously heated to maintain this temperature during welding. After welding, it shall be insulated with insulating cotton to cool it slowly. Quenching can increase the strength and hardness of steel pipe, but reduce its plasticity. Quenching agents commonly used in quenching include water, oil, alkaline water and salt solution. Tempering of precision steel pipe reheats the quenched precision steel pipe to a certain temperature and then cools it by a certain method, which is called tempering. The purpose is to eliminate the internal stress produced by quenching, reduce hardness and brittleness, and obtain the expected mechanical properties. Tempering is divided into high temperature tempering, medium temperature tempering and low temperature tempering. Tempering is often used in combination with quenching and normalizing. Quenching and tempering treatment the heat treatment method of high temperature tempering after quenching is called quenching and tempering treatment.
