前後方軸の組合せ押出し鍛造における押出し長さおよび荷重<br>に及ぼすビレット高さ/直径比の影響

Abstract

In this study, the effects of the shape ratio of a billet on metal flow and extrusion load in forward rod-backward rod combined extrusion forging were examined by experiment and analysis. Metal flow is affected by the shape ratio of a billet. When the shape ratio is 1.5, the rate of change in extruded length changes. When the shape ratio is 0.4, extruded length is proportional to the stroke. Extrusion load increases with the shape ratio of a billet. The internal crack generated in forward rod-backward rod combined extrusion forging grew with stroke. An estimation method for void volume in the deformed work piece by Archimedes' principle was applied to the analysis of the rod-rod combined extruded work piece of aluminum alloy at each stroke. The critical stroke at which a void was generated could be determined from the relationship between stroke and void volume. A ductile fracture criterion was obtained by the critical stroke and FE simulation. By using the obtained ductile fracture criterion and FE simulation, the critical stroke could be determined.