TO IMPROVE HIGH SPEED STEEL(DIN 1.3343) HOT-ROLLED FLAT BAR YIELD BY SIX-SIGMA METHOD

• Main Authors: Wen-Ruey Lee, 李文瑞
• Other Authors: none
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/82405728347680578662

碩士 === 國立中正大學 === 企業管理所 === 96 === After WTO entrance in future, the pace of import market opening will be faster. The competition for local industries to fight against exported steel goods will be definitely more violent. Some weak industries will be damaged or flunked certainly. In view of local market demands, because flat bar for building construction is affected by economic recession, the decline trend is shown. Under the blighting competition of low-cost flat bar available for mechanical structures exported from Mainland China, it has been improper for local makers to make products of general specifications. It is supposed to develop toward products featured with high additive values. Thus, the direct influence on markets posed by China products with low cost and fewer additive values can be avoided. Under the economic climate with incessantly soaring prices and increasingly violent competition of raw materials, it is required to evaluate the way how to make good use of Six Sigma kits to provide hot-rolled high speed steel flat bars with high quality, precision and additive values from the quality improvement rates of hot-rolled production techniques. As such, downstream makers can be favored with reduced cost, together with speedy, flexible and alert competition of industries. In addition, the product type gaps of local special steel markets can be well fulfilled to replace the import-depending industries in the past. This article is operated with case studies. Customers of high speed steel flat bars customarily procure black bars. Customers requested products with pre-arranged minimum dimensions for further processing to minimize the cost of raw material. In view of suppliers, makers can take the opportunity to replace the export-depending material ecotype only when black bars with stable quality and improved yield rates are provided. Thus, this study is aimed to explore the way to use Six Sigma in improving yield rates of high speed steel flat bars. This study is attempted to propose available solutions for reference through the process with issues and improvement experienced by subjects under our case studies. In this study, by using Six Sigma, it is aimed to discover the critical factors (Vital-X) affecting yield rates. By using the Finite Element Method, the hot-rolled simulation model can be created. The trial and error efforts can be saved remarkably. In combination with theories and practical discovery of optimal control methods, following problems can be solved. The said problems are: 1. critical factors affecting quality and yield rates, 2. verification of improved achievements under the control of critical factors, and 3. creation for the engineering design of hot-rolled simulation. It is expected that the win-win competence advantages of both companies under our case studies and relevant applicable industries can be reached. Finally, this article is proposed with the opinion that the critical factors to affect quality and yield rates are exactly the control over the selecting of hot-rolled billets and rolled volumes. Meanwhile, the engineering design with simulation dimensions is also created. It is allowable for on-site operators to adjust dimensions of hot roller grooves according to simulation dimensions. The trial and error efforts for practical hot rolling can be reduced with more excellent quality reachable. Keywords：High Speed Steel Flat Bar; Six Sigma; the Finite Element Method