Study On Design And Manufacturing Of Outer Doors With Super-thin And High Strength Steels

The restrictions to exhausts of automobiles have become stricter with air pollutionand energy crisis becomes even serious. One of the most important ways to reduce energyconsumptions is to reduce the auto-body weight. Light-weighting of auto-bodies hasbecome a common subject for all automobile companies. To manufacture parts with highstrength steels in place of mild steels and reduce the thickness of sheet metals, oncondition that the part and auto body properties are not reduced, is a way widely used inlight-weighting of auto bodies. Nowadays, different kinds of high strength steels havebeen widely used in automobile industries. But they are mainly used on structural partsand some other inner parts, and seldom used on outer panels. It is valuable to improve thestrength and reduce the thickness of outer panels for light-weighting of auto bodies.Based on previous studies, the present paper makes a deep investigation on thedesign and manufacturing of outer-panels for automobile doors with super-thin and highstrength steels. According to the results of many experiments on the door properties, suchas modes, rigidity and dent resistance, we find a most suitable design for super-thin andhigh strength steels. The main topics of the present paper are as follows:(1) Design of the door thickness based on super-thin and high strength steelsThrough finite element simulation and analysis of previous researches, the factorsthat have great affects on the rigidity and dent resistance of outer doors, and how thesefactors affect them are studied in the present paper. The minimal thicknesses for threedifferent high strength steels are determined.(2) Study on manufacturing of outer doors with super-thin and high strength steels.The fracture and spring-back in drawing are studied in the present paper. Throughprocess optimization, the problem of fracture is successfully solved. After a die compensation for spring-back, the spring-back is greatly reduced to an acceptable range.Experiments of door hemming show that the design put forward in this paper meet themanufacturing requirements.(3) Study on properties of the door based on super-thin and high strength steels.Mode, rigidity and dent resistance are the main parameters for evaluating theproperties of outer doors. In order to improve the properties of the door assembly, fivedesigns are put forward. Doors are manufactured based on every design with steels ofdifferent grades and thicknesses. Every design is evaluated through mode, rigidity anddent resistance experiments. The validity of the design put forward in this paper isvalidated and the most suitable design for super-thin and high strength steels aredetermined.