Research On Key Technologies Of Automobile Framework Covering Parts Progressive Stamping

In 2009, the yield of Chinese domestic automobile rose to 13.791 million units and exceeded some powerful nations like Japan, US and German taking the first place of automobile production in the world. The rapid growth of automobile industry boosts the development of die of automotive covering parts.Automotive covering parts include outer covering parts, inner covering parts and framework covering parts. Outer covering parts and inner covering parts are the stamping parts exposed on the external auto body and inside the auto body. Framework covering parts are the stamping parts to link and strengthen the inner and outer covering parts. These three kinds of covering parts are welded to form the auto body.Compare with general stamping parts, framework covering parts have the characteristics of big structure size, complex shape, multidimensional space curved surface, etc. framework covering parts are generally manufactured and completed by progressive stamping forming technology including blanking, bending, local deformation, flanging, restriking, piercing and cutting.This thesis takes the progressive stamping forming of BMW F45 reinforce D column(left/right)as the object of study and mainly accomplishes the following tasks: making a product stamping manufacturability analysis of reinforce D column and studying out the plan of 10-stations progressive stamping forming technology as well as blank layout; simulating the progressive stamping process of reinforce D column and predicting the different possible defects that may occur in the forming process by using the software AUTOFORM.; studying out the accurate design method of blank; relatively deeply study the design of progressive die structure; proving the reliability and accuracy in using software AUTOFORM to make finite element numerical simulation and the rationality of die structure design through test.It has been proved in the practices that the research results have guiding significance on designing progressive stamping technology of automotive framework covering parts and progressive die structure. The main research contents and conclusions in this thesis are summarized as followed:(1) Framework covering parts are generally bilateral symmetrical parts. It is considerable to stamping form this kind of covering parts in the same set of die, which can reduce the cost of die manufacture.(2)In framework covering parts stamping technology, the separating station is completed first, like piercing pilot hole and edge piercing,which is followed by the forming station like local deformation, bending, flanging and restriking. Finally, the station like piercing and cutting will be finished.(3) Framework covering parts are generally not arranged trimming and instead, accurate design methods for shape and size will be applied. The size requirements for shape of blank can be satisfied by using AUTOFORM.(4) Generally, the method of single-station and multi-process finite element numerical simulation for framework covering parts can meet the needs in forming analysis by using AUTOFORM. If any defects like fracture and wrinkle occur in the simulation, they can be solved by modifying the plan of stamping technology or the design methods for blank shape and then simulate again.(5) The method of single-station and multi-process finite element numerical simulation can be made by AUTOFORM, which can relatively accurately predict the variation in thickness of formed parts. For reinforce D column, the maximum relative error of prediction is 2.88 percentage.(6) The size of springback can be predicted and springback compensation can be done by using AUTOFORM. Generally, the size of springback of framework covering parts is relatively small. Thus, the effects of springback can be ignored at the initial stage of die design and the die structure can be modified according to the actual springback value at the later stage.(7) This thesis conducts deep research of progressive die structure by taking the example of reinforce D column, and summarizes the design methods as well as the key points.(8) Through the punching test, it is proved that the confirmed plan of stamping technology, the results of finite element numerical simulation and the die design methods are workable and applicable, which has guiding influence on real progressive stamping forming technology and die design.