Determination of Effects of Exit Positions and Extrusion Ratios on FormingCurved Rectangular Bars and Tubes by Finite Element Analysis

Abstract

In this paper, we describe the mechanisms responsible for the forming of rectangular bars and tubes extruded through inclined dies by numerical simulations and experiments. We carried out simulations and experiments of rectangular bars and tubes at various exit positions and extrusion ratios. The calculated trend of curvature showed good agreement with experimental results. From this reason, the validity of the numerical simulation was concluded. Curvature generation mechanisms were elucidated on the bases of simulation outputs related to the distributions of the material exit velocity and dead metal area. The turn direction differs according to the difference in exit position and the curvature increases with extrusion ratio as observed from the analytical results. The generation of dead metal area and the configuration of the container used affect the curvatures of curved rectangular bars and tubes.Key words: extrusion，forward extrusion，FEM，deformation behavior，manufacturing system. 緒 言 鍛造や板成形時のフレキシブル加工技術について多くの 検討がなされている

Effects of Die Dimensions for Curvature Extrusion of Curved Rectangular Bars

“…Previous studies have revealed that the material exit velocity in the upper and lower parts of the exit affect curvature. 6) This study also verified by simulation that the material was squeezed out along dead metal regions, and that the material exit velocity increased in the upper part of the exit where the dead metal volume is large, as depicted in Fig. 6.…”

“…6,7) However, because the extrusion ratio is the ratio of areas, the effects of the aperture height ratio and the aperture width ratio are not necessarily equivalent. It is therefore necessary that each be evaluated independently and that the die thickness effect also be examined, for detail investigation of the die dimension effects.…”