Component specific elastic cushion design to enhance the accuracy with the usage of reconfigurable tools in stretch forming

Multi-point stretch forming (MPSF) is a flexible manufacturing technology that uses reconfigurable tools to produce a variety of three-dimensional sheet metal components. An elastic cushion is placed between the surfaces of reconfigurable tool and the sheet metal to reduce the possibility of dimple formation. It is well known that elastic cushion deformation behavior significantly affects the accuracy and surface quality of components. In the present work, a component-specific elastic cushion is designed to achieve better conformability between the pin heads and cushion (by scooping out the material from the flat cushion selectively). An analytical model is developed to determine the volume of material to be scooped out and its location based on pin head and component geometries. To demonstrate the effectiveness of the developed methodology, finite element analysis (FEA) is performed to form double curvature (spherical) component with a cushion of constant thickness and a component-specific cushion with different pin matrix sizes. Results indicate that the deformation is more uniform with significant improvement in shape accuracy of the component formed with a component-specific cushion.