前方後方押出しによる複合ギア成形 : 成形性と金型応力に及ぼすスラグ形状の影響

概要

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The compound gear has a gear on one side and a cam profile on the other side. It is used in a seat belt system for an automobile. The compound gear has been produced through multiple forging processes and cutting processes. From the requirement for the lower costs of production and labor saving, it is very important to reduce the number of forging processes. So, the compound gear forming by the forward-backward extrusion in the cold forging was attempted. But it is very difficult to obtain the product without the defect, and the damage of the die sometimes occurs. In this study, to obtain the suitable slug shape for improving formability of the slug and preventing the damage of the die, 3D finite element simulations for the forward-backward extrution process using several types of slugs with the different shapes in cross section and the same volume were carried out, and the relationship between the slug shape and its formability and the influence of the slug shape on the stress of the die in the extrusion process were examined in detail. On basis of the obtained results, the suitable slug shape which was able to be formed into near net shape of the product and which could be formed in the lower extrusion load were proposed. The effects of the proposed slug shape on the forward-backward extrusion in the cold forging were also confirmed by the finite element simulation and the experiment.
2010-10-25