Major Advantages
1, Improve the surface roughness, and the roughness can basically reach around Ra ≤ 0.08 µ m.
2, Correct roundness and ovality can be ≤ 0.01mm.
3, Improve surface hardness to eliminate stress deformation, and increase hardness by HV ≥ 4 °.
4, After processing, there is a residual stress layer, which increases the fatigue strength by 30%.
5, Improve the quality of the fit, reduce wear, and extend the service life of the parts, but the processing cost of the parts is actually reduced.
Processing Technology
The cylinder tube is processed by rolling. Because the surface layer has residual pressure stress, it helps to close the surface micro cracks and blocks the expansion of erosion. This improves surface corrosion resistance and can delay the generation or expansion of fatigue cracks, thereby improving the fatigue strength of the quilted tube.
By rolling forming, a cold work hardening layer is formed on the rolling surface, reducing the elastic and plastic deformation of the contact surface of the grinding pair, thereby improving the wear resistance of the inner wall of the grinding tube and avoiding burns caused by grinding. After rolling, the reduction of surface roughness value can improve the fitting properties.
Rolling Processing Principle
Rolling machining is a pressure finishing process that utilizes the cold plastic characteristics of metals at room temperature to apply a certain amount of pressure to the surface of the workpiece using rolling tools, causing plastic flow of the surface metal of the workpiece and filling it into the original residual low concave valleys, thereby reducing the surface roughness of the workpiece. Due to the plastic deformation of the surface metal being rolled, the surface structure is cold hardened and the grains become finer, forming a dense fibrous structure and a residual stress layer. The hardness and strength are improved, thereby improving the workpiece surface's wear resistance, corrosion resistance, and compatibility. Rolling is a non-cutting plastic processing method.
Therefore, this method can achieve both finishing and strengthening purposes simultaneously, which cannot be achieved by grinding. No matter what processing method is used, refined and uneven tool marks will always be left on the parts' surface, resulting in staggered peaks and valleys.
CHEMICAL COMPOSITION(%) | ||||||||||
Steel Grade | C% | Mn% | Si% | S% | P% | V% | Ni% | Cr% | Mo% | Cu% |
CK45 | 0.42-0.50 | 0.50-0.80 | 0.17-0.37 | ≤0.035 | ≤0.035 | / | ≤0.25 | ≤0.25 | / | ≤0.25 |
ST52 | ≤0.22 | ≤1.6 | ≤0.55 | ≤0.04 | ≤0.04 | 0.02-0.15 | / | / | / | / |
20MnV6 | 0.17-0.24 | 1.30-1.70 | 0.10-0.50 | ≤0.035 | ≤0.035 | 0.10-0.20 | ≤0.30 | ≤0.30 | / | ≤0.30 |
42CrMo4 | 0.38-0.45 | 0.5-0.8 | 0.17-0.37 | ≤0.035 | ≤0.035 | 0.07-0.12 | ≤0.03 | 0.90-1.20 | 0.15-0.25 | ≤0.03 |
40Cr | 0.37-0.45 | 0.50-0.80 | 0.17-0.37 | ≤0.035 | ≤0.035 | / | ≤0.30 | 0.80-1.1 | / | ≤0.03 |
MECHANICAL PROPERTIES | ||||||||||
Material | Tensile Strength Rm (Mpa) | Yield Strength Rel (Mpa) | Elogation A% | CHARPY | CONDITION | |||||
CK45 | 610 | 355 | 15 | >41J | Normalized | |||||
CK45 | 800 | 540 | 20 | >41J | Q+T | |||||
ST52 | 500 | 355 | 22 | Normalized | ||||||
20MnV6 | 750 | 590 | 12 | >41J | Normalized | |||||
42CrMo4 | 980 | 850 | 14 | >47J | Q+T | |||||
40Cr | 1000 | 800 | 10 | Q+T |
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