Study On Pass Optimizing Process And Recessive Folding Defects For Ф50 Round Bars In Ф650 Mill

In resent years, with the great development of automobile and motorcycle industry, demand of steal in this area get more and more large. As an important steal in automobile and motorcycle industry, bar have large demand especially in Chongqing. In 2004, "bar series product in automobile and motorcycle industry"technology project was finished. Series of bar product in automobile and motorcycle industry was developed successfully. When using bar of Chongqing iron and steel company, Buyers produce two problems, one is that quality claim amount is large for users, another is that quality rejudge lead to large loss for manufacturer. Bar's crack defect and recessive folding defect are the main reasons for quality problem. Crack defect belong to steel-making problem and recessive folding defect belong to rolling problem. For rolling mill, solving folding defect especially recessive folding defect become a key and difficulty to improve bar product quality. Roll pass process 's optimization and rolling mill adjusting ability's improving become the research item.This paper introduced the process of producing bars and researched the process and shapes about folded defects. A new design method of edge oval pass for round bar was supplied toΦ50 round steels across the optimizing process. Researching the adjustment of roll gap about mill(Φ650×2/Φ550×4), made the new pass system fitting the adjustment of roll gap . Roll pass process 's optimization and rolling mill adjusting ability's improving become the research item.Investigated the folded defects shapes in different productions, analyzed the causation about the folded defects. Description is also made of change in rolling mode and process development,enhancement of thickness accuracy of the equipment and product quality index,etc by using existing equipment,showing that modification of hydraulic mill is effective, confoming to economic and technical requirements.The main research objective of this paper is optimizing process parameters for the eighth,ninth and tenth roll passes. It is easy to predominate the adjustment of roll for workers. The transformation of the former pass,on the premise of satisfying the on-the-spot working condition,can guarantee the production of rods of big specification. And at last the optimum result is appraised and analyzed. It is the result that obviously reduced round bars about recessive folded defects and folded defects. The wear of rolling ark is uniform. From metal deformation the guide way the adjustment principle and the adjustment of folded defects, studied on the mill adjustment. The operation of workers were increase Improved the quality and reduced the folded defects.The problem about folded defects was figured out, improve quality ofΦ50 and other specification round steels that produced inΦ650 section mill. The optimizing process can improve the work effiency, decrease the cost of production, have good economic returns. In according to the promotion of quality management could increase the comprehensive management level so as to promote enterprises'competitive ability eventually.