Study on the metal flow of large marine full-fiber crankshaft processed by TR bending-upsetting method

摘要

Large marine crankshaft is the heart of medium-speed diesel engine. The TR forming method used to obtain full-fiber workpiece is considerably complex. However, the metal flow behavior during bending-upsetting process, which determines the forming quality, was seldom studied in previous works. In this study, a finite element model (FEM) was established using constitutive model of 42CrMo4 steel and specified boundary conditions. The simulated results has demonstrated that the early filled metal resists the following metal entering the upper cavity, thereby causing the flash on the upper edge and the unfilled defect on the lower edge of the crank-arm. Further analysis has indicated that larger initial angel of the elbow rod θ_0 and a good lubrication condition between dies and workpiece can effectively decrease the volume of flash and eliminate the unfilled defect on the final product.