Die cavity design of near flashless forging process using FEM-based backward simulation

Preform design in forging processes is an important aspect for improving the forging quality and decreasing the production cost. Forward and backward simulations of the forging process based on rigid visco-plastic finite element methods (FEMs) can directly provide a preform shape from the final forged shape at a given stage. The objective of this effort is to reduce the material lost as flash by the design of an improved busting operation for a track link forging. This paper uses the FEM-based inverse die contact tracking method to design the preform shapes for a representative plane-strain cross section of the track link blocker forging. This procedure establishes a record of the boundary condition time sequence via forward simulation, using a candidate preform, into the final forged shape. This recorded time sequence is then modified according to the material flow characteristics and the state of die fill to satisfy the requirement of material utilization and forging quality. The modified boundary condition sequence is then applied to control die/node separation during the backward deformation simulation. The backward simulation for the section analyzed provided the blocker preform shape from which the buster dies can be designed. The preform for the section is then evaluated by forward FEM simulation and compared with the results from the original busting operation. Performance measures for the comparison includes die fill, flash size, strain variance, frictional power and die load. Use of round billet stock was also investigated for producing the required preform shape.