Influence of Friction and Elastic Shape Recovery on the Development of Corrugations under Oblique Plate Compression in Die Tooling

Abstract

Reshaping the corner-shaped parts is an urgent technical problem making it possible to provide wall thickening at the top by compressing the artificially created excess metal in the shelves of the semi-finished product. However, shelf compression is accompanied by formation of the corrugations, which are partially deflected by the die planes and remain in the waviness form after the load is removed. Regularities in the corrugations development during the shelves’ compression were established and primarily dependence on the friction forces acting on the die boundary surfaces, which is necessary to comply with the requirements to the workpiece shelves waviness. The workpiece shelves’ compression was simulated by compression of a plate placed obliquely in the die cavity. It is shown that the number of corrugations increases with the compression stress growth. The corrugations amplitude also increases during compression. When corrugations and die walls are in contiguity, contact stresses and friction forces act on the deformable plate. This shields the compression force action in the plate behind the contact point. Localization of deformations in the area in front of the contact point contributes to an increase in the thickness of the angle-shaped workpiece during reshaping. It was established that the residual waviness was non-uniform over the plate, and was associated with the deformation area localization, and was proportional to the initial gap