靜水壓擠製之液相能量消耗分析

Abstract

靜水壓擠製為一種不同於傳統擠製的金屬成形方法，其主要特徵在於利用液體將壓力均勻的施加於擠製錠上，而非直接利用擠桿施加壓力。擠製錠周邊的壓力於模具出口處較入口處低，利用此壓力差使得擠製錠流動，通過模具而改變斷面形狀。 本研究乃利用實驗方法有系統的探討靜水壓擠製中能量的消耗。理論方面則根據過去的研究提出的假設視流體部分為管流，金屬部分為剛塑性變形而以極限解析中的上界法分析其變形所需要的能量。本研究以靜水壓擠製時液體及擠製錠所消耗的能量應趨於最小之假設，分別求出加工過程中液體和擠製錠的能量損耗，並與傳統擠製所需之能量互相比較，增加我們對靜水壓擠製之知識。

Hydrostatic extrusion is an extrusion process where the billet is completely immersed in pressurized liquid. Pressure at the die orifice is lower than that at the die entrance, and the resulting pressure differential causes metal to flow, which produces products with different cross sectional areas from the billets. The force required to push the billet through the die thus is provided by the hydrostatic pressure instead of direct ram force. The purpose of this research is to investigate the energy consumption in hydrostatic extrusion systematically by experiment. The analysis of fluid depends on a pipe flow model and the simulation of material deformation is based on the upper-bound theorem. Total energy minimization is obtained through simplex optimum method. Finally, the theoretical analysis will compared with experiment to find out the fluid energy consumption in hydrostatic extrusion. The results indicate that fluid in the area that material deformation takes place consume most of the energy required for hydrostatic extrusion.