Study On The Stiffness Analysis And Design Technology For An Automotive Body Panel Stamping Die

Presently China has been the greatest automobile manufacturing country and sales market in the world,and the automobile industry has been one of the pillar industries of national economy.During the manufacturing process of automobile components and parts,a stamping die used for making car body panels is an important production equipment and plays an important role in whole automobile industry.Traditionally,by the stamping die design method,one die is regarded as a desirable rigid body,and an engineer often assumes that it has enough stiffness,taking no consideration of its elastic deformation in whole stamping process.Moreover,because there is a lack of reliable and efficient foundations for die structure solution and its design parameters selections,those selections depends on an engineer's practice experience and some empirical formulas.After manufactured,in stamping process,sometimes a die comes into being excessive deformation,resulting in making metal forming quality worse because of die's stiffness deficiency,or a die has a so excessive stiffness that it has a large volume and mass amount,resulting in die manufacturing material wastes and a high cost,bringing about an overload for an enterprise.Summarily,how to ensure a die with a rational stiffness so that it can stamp a sheet metal with excellent forming quality and also the die has a much less material waste and manufacture cost is a problem to which is worthy of paying attention.Aiming at solving this problem mentioned above,this paper introduced one method,which obtained loads value of all local shaping surfaces of a die by means of CAE simulation technique.Subsequently,in FEA software,mapping these surfaces loads to the die solid structure to analyze the stress conditions and deformation conducts,then the whole die's strain-stress and surface deformation distribution contours were obtained.Subsequently,according to these above results,some surface regions which had excessive or too small stiffness were confirmed,then the thickness of die shaping surface and the distribution and thickness of reinforcement ribs on the bottom of the die were optimized to acquire a more reasonable die structure to ensure good forming quality and reduce the volume and mass amount of the die,and also reduce its manufacturing cost.Above all,in this paper,the routine method of die structure design and design parameters' selection was retelled.The worse influence to forming qualification because of too small stiffness and the higher manufacturing cost because of excessive stiffness were discussed,and also the rational stiffness of one die in stamping process was studied.One solution how to transmit loads from shell surface mesh to solid structural mesh was studied,and the theories including sheet metal forming,the FEA of mechanical structure and contact problem,FEA optimization were discussed and summarized.Then,taking a die for example which stamped an exterior cover of a car boot,one method was systematically presented which included creating numerical models of blank and die in CATIA,inputting these models into Ansys Workbench to construct a structural FEA model,extracting the outer shaping surfaces of the die to import into Dynaform to simulate the forming process of the boot exterior cover to obtain the loads of die surfaces.The results from these operations laid a foundation for die structure analysis later.Based on the results above,the die structure analysis was finished in Ansys Workbench,and the stress-strain and displacement distribution contours of the whole die were achieved.Then,the whole and local stiffness of the die were discussed.Taking the die shaping surface and reinforcement ribs as study objections,its' structure distribution was schematized by strengthening the too small stiffness and reducing the excessive stiffness of the die's local constructions,thus a more reasonable die structure was acquired,to meet the good forming qualification and die structure simplification objectives.After all this work,an analysis results comparison before and after structure optimization was presented,and the amounting indexes of the sheet metal forming qualification improvement and die mass and manufacturing cost down were obtained to test the validity of these study work.Lastly,this die's FE contact analysis model was constituted,and the die structure analysis results before and after optimization were regained by contact analysis in FEA software to test the correctness of all above CAE analysis and optimization work.The results showed that the die with construction optimized by the method illustrated in this paper can reduce the deformation in forming process to ensure better forming qualification of a sheet metal,and meanwhile the mass and volume amount of the die were also reduced to some extent,so the die was simplified and the material waste and manufacturing cost were reduced.As a result,this analysis and optimization technology expressed in this paper takes on some practical reference value for improving forming qualification of a sheet metal and reducing the manufacturing cost of a die.