Analysis Of Abrasion Failure Of Sink Roll System In Hot Dip Galvanizing Line

There is a hot-dip galvanizing line in Meishan Iron&Steel Ltd. Under the corrosion of liquid zinc and abrasion between the sleeves and bushings with heavy load, the sleeves and bushings in sink roll system would be worn out failure in a short time, the online life cycle of sink roll system was also decreased obviously. It was limited less than 15 days, resulted in increased cost of production and low production efficiency. According to the on-site investigation, it indicated that the abrasion of the sleeves was serious, it could be the dominant influencing factor.The mechanical analysis indicated adjusting the inserting scale of correcting roll had little effect on the sink roll, but the effect of inserting scale on stabilizer roll and correcting roll was quite different. Reasonable inserting scale had positive impact on the stability of the system. The analysis of force and deformation of the system showed that the strength and stiffness had little problem and had not influence on the online life cycle obviously, so it was not proper to adjust the structure of the system.According to the wear mechanism, it was inferred that the abrasion was related to the surface hardness of the material. The analysis for hardness and material of original sleeves and bushings indicated that the materials selection and hardness ratio between the sleeves and bushings were improper. The hardness of sleeves and bushings of sink roll were close to each other, but the difference between the hardness of sleeves and bushings of stabilizing roll was large, resulted in serious wear of stainless sleeves and decreased the online life cycle of sink roll system. Based on the analysis results, optimizing materials and changing the hardness between the sleeves and bushings were determined. The hardness of modified sleeves of stabilizing roll was increased, whereas the hardness of bushings was decreased a little, also the hardness of modified sleeves of sink roll was a bit higher than bushings. After improvement the abrasion of the sleeves was reduced significantly and the online life cycle of sink roll system was increased from less than 15 days to 20 days.