Hydrostatic Extrusion of Composite Rods
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 flow, the force required to push the billet through the die thus is provided by the hydrostatic pressure instead of direct ram force. Composite rods or wire can be composed of two or more different materials, and each material has its own distinctive mechanical characteristics. Because a composite rod billet is deformed more uniformly in the hydrostatic extrusion process than in the conventional extrusion, it is considered hydrostatic extrusion is one of the most effective processes for manufacturing of composite rods and wires. The aim of this thesis is to propose an analytic model for hydrostatic extrusion process. In this model the liquid surround the billet will be considered to be one kind of hydrodynamic lubrication and upper-bound theorem will be adopted for the analysis of the deformation of composite rods or wire. Model describing the plastic flow of the above mentioned clad rods was established. Work-hardening effects of the materials are taken into account. The results show the deformation behaviors of billets under hydrostatic extrusion with different processing parameters. Finally an experiment of the hydrostatic extrusion of round rod was conduced, and its results were found very close with the analysis.
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