بررسي مسايل اكستروژن معكوس براي توليد قطعات با شكل داخلي دلخواه از بيلت هاي دايره اي با استفاده از روش حد بالا

An Investigation of Reversed Extrusion Problems for the Production of Arbitrary Internal Shaped Parts from Rands Billets

Backward exterusion is one of the metal forming processes that have been developed for use in industries in recent years. In this paper ,an upper bound analysis of the backward extrusion process of tubes of arbitrary shapes from round billets is carried out .A new kinematically admissible velocity field is proposed. Using this velocity field, the upper bound expression is determined and is minimized with respect to optimizing parameters. Results for ellipse and gear shaped punches are shown in diagrams that indicate extrusion load and gauge pressure variations with reduction of area, shape factor and friction factor variations. These results are compared with experimental and theoretical results of other researchers. Agreements of the present work with the experimental results have been observed for higher values of reduction of area. For low values of the reduction of area observations of the present and experimental work show some differences.