The Effects of Friction at Tool Surface on Plastic Flow and Bulk Deformation Analyzed Quantitatively by Plane Strain Extrusion Experiments

摘要

An experimental apparatus of plane strain forward extrusion, in which one side of the facing tools was the plane plate tool and the other side was the container wall and flat die, was used to measure the effects of lubricating conditions at the plane plate tool on bulk plastic deformation of a billet in steady-state extrusion. The plane strain extrusion experiments and deformation analysis of aluminum (JIS-1050) billets were carried out under different lubricating conditions by applying the visioplasticity method. Another experimental apparatus, in which both sides were the container walls and flat dies spacing twice of the container cavity width of the former apparatus, was introduced, so that the symmetric plastic flow with regard to the central axis of the container cavity could be obtained. The plastic flow observed in half of the assembled billets, contacting together along on the central axis of the container cavity, could represent the plastic flow with no frictional constraint at the plane plate tool in the former apparatus. An introduced friction-free result makes it possible to comprehensively compare and exactly analyze the net effects of frictional constraint at the plane plate tool on the flow characteristics of material at the given lubrication.