PRESS-FORMING METHOD FOR JOINED STOCK

PURPOSE:To slowly perform the deformation in the course of press-forming by providing an inclined surface made by the difference between plate thicknesses and the length exceeding a specific times the difference on a lower (or an upper) die of a press die and positioning a stocks joining part on the inclined surface. CONSTITUTION:The clearance step 12 on the lower die 11 of the press die is an inclined surface and the level difference t is equal to the difference between the plate thicknesses in the joined stock to be pressed and the length S exceeds 50 times as long as t. The upper die of the press die is flat and abuts on the flat surface of the joined stock. Joined (laser-welded) stock of plates different in thickness is press-formed by the lower die 11 and a flat upper die so that the joined part different in level comes to a clearance step (inclined surface) 12. S/ T is changed in a range 50-140, and the larger the ratio S/ T is, the smaller the strain quantity ratio H/L of the strain height H near the joined part to the strain range L is. Thus, the deformation in the course of press-forming is made slowly on the inclines surface and the clearance step corresponding to the difference between plate thicknesses does not make trouble to forming.