Research Of Arithmetic About Surface Mapping Base On Compensation Of Spring-back In Sheet Metal Forming

Sheet metal forming, as an important method for manufacture of plastic working, is widely used in automobile, aircraft, electronic instrument, shipbuilding, apparatus and other industries. In sheet metal forming, wrinkling, cracking and spring-back are the main problems, amongst which spring-back is the most difficult one to be controlled. The phenomenon of spring-back greatly affects precision of parts and manufacture efficiency, so it is necessary to do further research to control the spring-back.The spring-back die compensation method is that modify the die's shape according to the value and distribution of its spring-back, and then make its shape after spring-back match the requirement of geometric precision. It is difficult to measure magnitude and distribution of spring -back value in engineering practice, and it is difficult to ensure part's geometric precision by using traditional die compensation method. Consequently, it is one of the hot points in sheet metal forming field that how to use numerical simulation to predict spring-back value and then reduce part's geometric error. It is very important that how we can transform the ultimate die's CAE geometrical model after die compensation into CAD geometrical model to be convenient for CAM processing then build CAD/CAE/CAM integrative system which is based on spring-back compensation. Therefore, research of surface mapping base on compensation of spring-back in sheet metal is very necessary and vital. The thesis mainly deals with:Systematically introduces the fundamental mathematic theory and approach closely related with the surface modeling , which building up the bases for the surface mapping and conjunction;Build the relation among nodes of original elements, original surfaces, boundaries of original surfaces, the target elements and new surfaces. Sort the original surfaces and establish the sequence of surface mapping. Using the lease square method builds new surfaces which original surfaces corresponding on target elements one by one. Realize the function that mapping the original surfaces on the target elements;Aiming at condition that the concatenation between the new surfaces are not very well, we give the arithmetic about surface G0, G1 joining, in order to satisfying the requester in industry application;Upon the study of above technology, the thesis applies surface mapping and surface conjunction of Auto Panel Die-face algorithm into Die-face Engineering module of CAE software which the author participated in development. The module has a convenient function and high implementing efficiency, which shortens mold design and manufacturing period, reduces cost and improves quality of mold product significantly.