Forming of tailor blanks having local thickening for control of wall thickness of stamped products

A two-stage forming process of tailor blanks having local thickening for controlling the distribution of wall thickness of stamped parts was developed. In the 1st stage, the target portion of the sheet for the local thickening is drawn into the die cavity, and then the bulging ring is compressed with the flat die under the clamping of the flange portion in the 2nd stage. The effects of the punch stroke, the clearance between the punch projection and die, and the projection width on the amount of the location thickening were examined. A 12% increase in thickness of the blank was obtained in an experiment. The tailor-formed blank having local thickening was applied to increase the wall thickness at the inner corner of a wheel disk. An 11% increase in wall thickness at the inner corner was successfully obtained in the experiment. The tailor blanks having local thickening obtained by the two-stage forming process are effective in controlling the distribution of wall thickness of the stamped parts.