980MPa급 초고장력강 비대칭 Seat Rail 성형에 관한 연구

Abstract

Recently, environmental pollution and rapid increase of automobile demand have strengthened automobile fuel consumption and exhaust gas regulations in various countries, and global automobile companies have been continuously reducing the weight of vehicles to improve fuel efficiency. Therefore, the material of the body has to be made thinner and higher in strength as it has to be made lighter with improved performance. Since the seat occupies 3 to 5% of the weight of the vehicle, researches for developing lightweight sheet components utilizing Ultra High Strength Steel have been continuously carried out. Among them, the seat rail is the most actively studied part of the application of UHSS. Roll forming and cold press forming are most commonly used for sheet rail forming of UHSS. Roll forming is advantageous for manufacturing Long- Rail, but cold forming is preferred because of its high productivity. Therefore, in this study, we developed an efficient process by predicting the problems occurring in 980Mpa asymmetric lower rail development using cold press forming technology. An appropriate process to control the spring back and twisting problems caused by the asymmetric bending process of UHSS is presented through analysis and experiment.  After the die development and bending process, the major dimensional accuracy of the product was confirmed. Finally, the product was assembled with Seat rail, and the effectiveness of the manufacturing process was verified by evaluating clearance, operating force, and strength.