Development of die design strategies for precision forging of complex parts: Compensation of die deflection development of multiple action tooling for forgings with undercuts

The term precision forging does not describe a particular forging process, but rather an approach to forging. The goal of precision forging is to produce parts with complex functional surfaces to very close tolerances that otherwise would be made by expensive machining operations.; In recent years the forging industry is using increasingly FEM process simulations, to determine metal flow to design forming sequences and to predict forming loads. However, this approach has not been used extensively for the compensation of die deflection, which is still a trial and error process.; In this research a methodology to systematically compensate for die deflection has been developed. This methodology allows the designer to use the information generated during the process simulation, i.e., contact stresses and temperature distributions to perform the stress analysis of the tools and compensate for the deflection of the tooling. Verification of the die correction through a simulation with a plastic workpiece and an elastic die has help to validate this approach.; Some of the components traditionally manufactured by machining are currently being forged to near net or to net shape at high production rates. However, the production of components with undercuts has been limited to the aerospace industry, where because of the size and complexity of the components material savings achieved by forging justify the use of expensive tooling. In this study, design guidelines for multiple action tooling are developed to forge automotive parts with undercuts. Analytical equations were developed to determine the size of the tooling based on stresses and allowable deflection of the tooling. The design guidelines have been verified by comparing the calculated results with FEM structural analysis results. The loading on the dies was obtained through 3D FEM process simulation.; In addition a multiple action tooling for physical modeling for the cold forging of a cross groove inner race was constructed. Qualitative as well as quantitative evaluation of the results is possible by knowing the flow stress relationship of the model material and that of the actual metal. Thus, this study demonstrates that physical modeling can be used to estimate forging loads and to make engineering decisions based on physical modeling results.