Symmetric bending technology using a floating die to forge crank throws for marine engines

The critical step during open die forging of a large crank throw for a marine engine is bending the preform into a V-shaped blank. The blank may be bent in an inaccurate fashion due to its asymmetric shape, temperature non-uniformities, and/or any misalignment between the preform and the die. Correcting a distorted asymmetrically bent blank is difficult. Therefore, controlling the deformation during bending of a large crank throw is required. In this study, a new bending process that makes it possible to form a non-distorted, symmetrically bent blank is described by introducing the concept of a floating die. The feasibility of the proposed method is confirmed using test cases obtained from finite element simulation and scaled down model tests using laboratory prototype tooling. This technology will increase the shape accuracy of the bent blank and will save time during post-machining of a large crank throw.