Method of reducing springback in mechanically pressed sheet materials - i

Abstract From the Canadian patent

A method of pressing sheet material utilizing counterpad pressure to eliminate springback is disclosed. The sheet material is sequentially bent at paris of bend radii during first and second increments of striking. The first increment of striking is carried out with little or no counterpad pressure to permit a curvilinear section to form immediately beneath the male punch member due to the bending moment. The second increment of striking is carried out with a positive counterpad pressure effective to flatten the curvilinear section and thereby space the second pair of bend radii from the first pair. Residual springback from the first bending action subtracts from the springback of the …