Optimum Blank Design of Thick-Plate Metal Forming without Blank Holder

Many blank design methods are used in sheet metal forming industry, but most of them originated from applications of thin sheet metal forming with blank holder. There are few researches on blank design methods of thick-plate metal forming without blank holder, which process has two characteristics: workpiece thinning locally and severely, workpiece inside surface not contacting with top punch because of local bulk deforming. An optimum blank design method is proposed in this paper for the thick-plate metal forming without blank holder. This method consists of two stages: the initial blank design stage and the blank optimization stage. The first stage is to obtain initial blank shape using Inverse Finite Element Approach (IFEA) from the middle-thick layer of 3D model of target part. In the second stage, firstly, simulate and obtain deformed workpiece by forward finite element analysis; then calculate the shape error between deformed workpiece and target part, and the indicator ▵ of optimization procedure; finally, correct the blank shape by the feedback of shape error until the indicator ▵ is smaller than tolerance. In order to verify the proposed method, a reverse arm bracket is investigated.