Many types of punching processes are utilized in the production of automobile parts and other components. In normal punching with a punch and a die, a sheared surface and a fractured one are usually formed on the cut surface. Here, to produce highly accurate parts, it is important to estimate the ratio of the sheared surface to the cut surface and to economically produce smooth cut surfaces, optimal tools and punching conditions must be selected within the limits of cost constraints. The finite element method (FEM) has been applied to the analysis of the ratio of the sheared surface to the fractured surface on the cut surfaces. For this, the ductile fracture criteria for the fracture initiation of the cut surface have been proposed by several researchers. It is difficult to determine the fracture criteria on the cut surface by tensile tests or bending tests because the punching process consists of many complicated steps. In this study, we apply the FEM to four punching arrangements to evaluate the ductile fracture criteria proposed by Oyane and by Cockcroft and Latham. We find that the morphology of the cut surface is affected by clearance between the punch and the die, by blank holding conditions and by ductile fracture criteria.

The fine-blanking process is used in the production of automobile parts and other metal components. Although the fine-blanking process can produce sheared surfaces with higher precision than the punching process, shear droops on cut surfaces are also formed, as in the punching process. It is important to determine the causes of the formation of shear droops, but the mechanism is difficult to determine experimentally. Here, the finite element method (FEM) is adopted to study the causes of the formation of shear droops. The cut surfaces in the present experiments have fine sheared surfaces but no fracture surfaces. Although a combination of the fracture criterion and element-kill method is used for many simulations of the fine-blanking process, fine sheared surfaces cannot be evaluated by the combination of these methods. In the present calculations, an adaptive remeshing technique for FEM is used to create fine sheared surfaces. The shear droop is associated with the initial compression by and the subsequent clearance of the punches and dies. Results are obtained for various clearances and initial compressions in the fine-blanking process for high-strength steel, and the experimental and calculation results are compared. In the present paper, we show that the shear droops are affected by the clearance of and initial compression by the punches and die.

Many types of punching process have been utilized for the production of automobile parts and other related components. In the normal punching process that uses a punch and a die, both shear and fracture surfaces usually exist on the cutting surface. It is important to estimate the ratio of the shear surface to the cutting surface to produce highly accurate parts. To realize a smooth cutting surface of products, we have to apply the most appropriate tools and punching conditions to the process, taking account of the costs. The cutting surface of punching processes has been analyzed to study the ratio of the shear surface to the fracture surface by the finite element method (FEM). The criteria for fracture initiation on cutting surfaces have been proposed by several researchers. It is too difficult to identify the fracture criteria on cutting surfaces by simple experiments such as tensile tests, because the punching process has many complicated steps. In the present study, the finite element method is applied to several punching processes to evaluate the criteria of the ductile fracture functions proposed by Oyane and Cockcroft and Latham. As a result, the shape of cutting surfaces is affected by the clearance between the punch and the die, blank holding conditions, and the ductile fracture criterion.

The fine-blanking process is used in the production of automobile parts and other metal components. Although the fine blanking process can produce higher-precision sheared surfaces than the punching process, rounding edges on cut surfaces are also formed, as in the punching process. It is important to determine the causes of the formation of rounding edges. However, it is difficult to clarify the mechanisms of the formation of rounding edges by experiments. The finite element method is adopted to study the causes of the formation of rounding edges. The cut surfaces in the present experiments have fine sheared surfaces but no fracture surfaces. Although a combination of the fracture criterion and element kill methods is used for many simulations of the fine-blanking process, fine sheared surfaces are not evaluated by a combination of these methods. A mesh adaptive technique for the finite element method is used to create fine sheared surfaces in the present calculation. The rounding edge is associated with the initial compression and the subsequent clearance of the punches and dies. Results are obtained for various clearances and initial compressions in the fine-blanking process for high-tensile steel. The results of the experiments are compared with those of the calculation. In the present study paper, we show that the rounding edges are affected by the clearance and initial compression of the punches and die.

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