摘要：The purpose of this investigation is to characterizeand latter make a full development of variable metal sheetblank holding force (VBHF). Permanent blank holdingforce has been used so far (Fig. 1). The present paper is acontinuation of authors’ papers. Until present day optimaldependence of minimal blank holding force on punchtravel in order to avoid the wrinkles has not been identi-fied, even in theory [1-3]. All theoretical formulations ofblank holding force (BHF) describe only the maximum ofBHF, which does not describe nonlinearity in metal form-ing operation. From literature [4] we know the holdingmaximum pressure to the sheet should be around 1 -3 MPa. Several analytical equations have been invented orderived in order to characterize BHF. For example scien-tists [1, 2, 5] describes the following equation for neededBHF.
