Critical Conditions of Wrinkling in Deep Drawing of Sheet Metals : 2nd Report, Analysis and Considerations for Conditions of Blank-Holding

In this report, based on the equilibrium equation of moments induced in the first report, the critical conditions of wrinkling are considered and discussed for the case where a blankholder is used. In practice of deep drawing operation, we cannot but often allow arising of small wrinkles in a flange through various causes, but if the wave amplitude of wrinkles is lower than the allowable value, wrinkles do not practically remain in the product, since an effect of suppressing flange wrinkles exists in die radius. Thus, the allowable specific wave amplitude of flange wrinkles is deduced, and by introducing this into the equilibrium equation, a formula for prediction of the critical blank-holding pressure is induced.