Press Formability of an Inhomogeneous Sheet Metal

The improvement of the press formability of a sheet metal has been performed by the following procedure. First, benetificial characteristics are sought from the data in the actual performance of the press forming, and then the sheet producing conditions which make these characteristics dominant are examined. In our approach, basic features of the deformation elements composed in the press forming are confirmed first, and then preparation of a new sheet which has the characteristics conforming to these features is aimed at. That is, improvement of the formability is tries by proposing the idea of an inhomogeneous sheet metal which has hardness change in the thickness direction to conform to the strain distribution of the bending. The inhomogeneous sheet is simply prepared by some mechanical treatment and the following results are confirmed in this experiment. (1) In bending, the strength of the bent portion is improved. (2) In deep drawing, the limiting drawing ratio is remarkably increased.