2007 年 48 巻 552 号 p. 61-65
In this study, the effect of tool modeling accuracy on finite-element simulation of a square cup deep-drawing process is examined. First, the accuracy of tool modeling by a conventional approach, in which polyhedral surfaces are used, is compared with that of an alternative one, in which the quadratic parametric surfaces proposed by Nagata (Nagata patch) are used. It is clear that the Nagata patch yields a much more accurate tool model than the polyhedral surface in terms of tool shape and tool normal vector. Next, the simulations of the square cup deep-drawing process are carried out for various numbers of tool elements. It is clarified that a polyhedral tool with at least 10 patches at the die shoulder is required to carry out appropriate simulations. The simulated result of the Nagata patch tool with two patches at the die shoulder corresponds well to that of the polyhedral tool with more than 10 patches. From this point of view, it is concluded that the number of tool elements can be markedly decreased by using the Nagata patch tool. In the present case, the number of tool elements can be reduced to about 10% that of the polyhedral tool.