The reason why precision honing steel pipe is precise is that it has high precision and good tolerance control range. The wall thickness of the precision tube is uniform, the inner wall is smooth, and the surface is free of defects; The surface roughness is smoother than that of ordinary pipes. Finish-rolled pipe, also known as cold-rolled precision steel pipe, is a production process of seamless pipe. It has the characteristics of high precision and surface finish requirements, especially the seamless steel pipe for oil cylinder has higher quality requirements than other varieties.
Characteristics of precision honing steel pipe
The precision honing steel pipe has high tolerance dimension accuracy, the product accuracy is controlled within ± 0.5mm, the internal and external wall finish is good, and the surface is free of oxide layer.
With excellent comprehensive performance, it can withstand high pressure, cold bending, flaring, flattening without cracking and wrinkling, and can do various complex deformation and mechanical processing.
precision honing steel pipe process:
The honing steel pipe is processed by rolling. Because of the residual compressive stress on the surface layer, it is helpful to seal the surface micro-cracks and hinder the expansion of erosion. Thus, the corrosion resistance of the surface can be improved, and the generation or expansion of fatigue cracks can be delayed, thus improving the fatigue strength of the honing steel pipe. Through rolling forming, a cold work hardening layer is formed on the rolling surface, which reduces the elastic and plastic deformation of the contact surface of the grinding pair, thus improving the wear resistance of the honing steel pipe inner wall, and avoiding the burn caused by grinding. After rolling, the reduction of surface roughness value can improve the fit property.
Rolling processing is a kind of chip-free processing. At normal temperature, the plastic deformation of metal is used to flatten the micro unevenness of the workpiece surface to achieve the purpose of changing the surface structure, mechanical properties, shape and size. Therefore, this method can achieve both finishing and strengthening purposes at the same time, which is impossible for grinding.
No matter what kind of processing method is used, there will always be tiny and uneven tool marks on the surface of the part, and there will be staggered peaks and valleys,
Rolling processing principle: it is a pressure finishing process, which uses the cold plastic characteristics of the metal at normal temperature to apply a certain pressure on the surface of the workpiece using the rolling tool to make the metal on the surface of the workpiece produce plastic flow and fill it into the original residual low valley, so as to reduce the surface roughness of the workpiece. Due to the plastic deformation of the rolled surface metal, the surface structure is cold hardened and the grain becomes fine, forming a dense fibrous structure, and forming a residual stress layer, which improves the hardness and strength, thus improving the wear resistance, corrosion resistance and compatibility of the workpiece surface. Rolling is a plastic processing method without cutting.
Advantages of precision honing steel pipe:
1. Improve the surface roughness, and the roughness can basically reach Ra ≤ 0.08µ About m.
2. Correct roundness, ovality can be ≤ 0.01mm.
3. Improve surface hardness, eliminate stress deformation, and increase hardness HV ≥ 4 °
4. After machining, there is residual stress layer, which increases the fatigue strength by 30%.
5. Improve the fitting quality, reduce wear and prolong the service life of parts, but the processing cost of parts is reduced.
Difference between honing steel pipe and seamless steel pipe:
1. The main feature of seamless steel pipe is that it has no welded joint and can withstand large pressure. The product can be very rough as-cast or cold-drawn parts.
2. Honing steel pipe is a product that has emerged in recent years, mainly because the inner hole and outer wall dimensions have strict tolerance and roughness.
Features of honing steel pipe:
1. Smaller outer diameter.
2. High precision and small batch production
3. The cold-drawn finished product has high precision and good surface quality.
4. The cross area of steel pipe is more complex.
5. The performance of steel pipe is superior and the metal is dense.
Differences after hot-rolled honing steel pipes:
The hot rolled precision steel pipe uses continuous casting round tube blank or blooming slab as raw material, which is heated by a walking beam furnace, descaled by high pressure water, and then enters the roughing mill. The roughing material enters the finishing mill after cutting the head, tail, and then enters the computer controlled rolling. After the final rolling, it passes through laminar flow cooling and coiler coiling, and becomes a direct coil. The head and tail of straight hair curls are often tongue-shaped and fish-tailed, with poor accuracy in thickness and width. There are often defects such as wave shape, folded edge and tower shape at the edge. Its coil weight is heavy, and the inner diameter of steel coil is 760mm. The straight coil shall be cut or recoiled after finishing line treatment such as head cutting, tail cutting, edge cutting and multi-pass straightening and leveling, and then become hot rolled steel plate, flat hot rolled steel coil, longitudinal cut strip and other products. Hot rolled finish coils are formed after being pickled to remove oxide scale and coated with oil.