Shape rolling process development and experiments for die springs

• Main Authors: Chong-ChingTseng, 曾中慶
• Other Authors: Shi-Pin Ho
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/69839167421073208858

博士 === 國立成功大學 === 機械工程學系 === 102 === In recent years, environmental issues and high labor costs for traditional industry have been receiving increasing attention. One example is the manufacturing process of conventional oil tempered shaped wire that is high cost, time-consuming and polluting. The process of annealing or spheroidizing needs to be carried out before the shaped wire drawing processes, and acid pickling, phosphate coating, and wire drawing are required three or four times in sequence until the circular section is formed into a trapezoidal section. The roll pass design is an essential part of the shape rolling process, and the primary goal of the roll pass design is to ensure that the finished products have the correct profile, and are free of surface defects. In this study, we adopted the 2D generalized plane strain finite element method with thermal-mechanical coupling to solve the complicated shape rolling problem, because the 2D generalized plane strain approach saves computing time and computer memory, which is very useful when several subsequent passes are simulated. The aim of this study is therefore to attempt to solve the problems of producing shaped wire. This study investigates the shape rolling process combined with the in-line induction heat treatment process for tempered shaped wire. The round wire was heated to austenitic temperature using in-line induction heating equipment, and the wire was formed into a trapezoidal shape using a tandem cantilever type rolling mill, then quenched in water and tempered. Hence, the entire sequence was carried out in a single procedure with an automated line。 The advantages of the manufacturing process of this study are highly efficient, low cost, and more environmentally friendly than the conventional process, because there is no need for acid pickling, annealing or spheroidizing and phosphate coating. And the wire is heated to austenitic temperature by induction heating in a few seconds, so the heating process does not cause oxidation or decarburization on the surface of the steel wire. Finally, it is evidenced that the mechanical properties, microstructure and the fatigue testing results of the shaped wire all satisfied the requirements.