Idler Roller Textured Hard Chrome Plating Process

At present, some domestic steel mills have begun to apply textured chrome-plated rolls, and have achieved good economic benefits. The process used for the roller body textured hard chrome plating is:

1. Inductively quench the surface of the roll body first, with a quenching depth of 3-5mm, so that the surface hardness reaches HRC45-55. Then grind the surface of the roll body to make the roll surface roughness Ra ≤ 0.8μm, and there should be no spiral roll marks or grinding vibration lines. For rollers with high surface quality requirements, they need to be ground and polished to Ra<0.2μm. At the same time, the roller needs to be tested for dynamic balance. The weight removal method is used to drill small blind holes at the end of the roller to ensure that the balance quality level is higher than G16.

A tighter fit during operation. In addition, due to the effect of gas storage in the micro-pits on the roll surface, a protective gas film is formed between the strip steel and the roll surface, which avoids scratches on the strip steel on the roll surface. At present, the texturing technology includes: shot peening, electric spark texturing, laser texturing and other technologies. Among them, the laser texturing technology Z is advanced, but its use in China is less mature than the traditional shot peening texturing technology. After the surface of the idler roller is shot-peened, its hardness and fatigue strength are improved, and at the same time, it can effectively reduce the chance of slippage between the strip and the roller, and avoid the strip being scratched.

2. The roll surface is then textured to increase its friction coefficient and make it fit more closely with the strip during operation. In addition, due to the effect of gas storage in the micro-pits on the roll surface, a protective gas film is formed between the strip steel and the roll surface, which avoids scratches on the strip steel on the roll surface. At present, the texturing technology includes: shot peening, electric spark texturing, laser texturing and other technologies. Among them, the laser texturing technology Z is advanced, but its use in China is less mature than the traditional shot peening texturing technology. After the surface of the idler roller is shot-peened, its hardness and fatigue strength are improved, and at the same time, it can effectively reduce the chance of slippage between the strip and the roller, and avoid the strip being scratched.

3. After Z, the surface of the roller is electroplated with hard chromium. The thickness of the electroplating layer is 0.05-0.15mm (not more than 0.20mm), and its hardness can reach HV900-1000. Before electroplating, the roller body should be degreasing and cleaned, and the quality of the roller surface should be strictly inspected. Defects such as pores, cracks, rust, and scratches are not allowed. After electroplating, the surface of the roller is required to be bright and flat, with no color difference, and be subjected to grinding and peak-cutting treatment.