Abstract: Accurately calculating flanging forming forces has important theoretical and practical significance to the correct selection of processing equipment, rational design of forming dies and scientifically formulating process planning. Because of the complexity of the problem, approximate calculation of the flanging force according to empirical formula or simplified model will reduce the calculation precision. Analysis on the existing methods of flanging force calculation is carried out from the aspects of mechanics principle and calculation precision, the problems in the original theory are pointed out, the solution process of flanging force is analyzed on the basis of considering the thickness variation of deformation zone and adopting the power function hardening law, a new mathematical model of hole flanging force is built and a new calculation formula is derived. In order to verify the correctness of the new formula, flanging forming tests are carried out on two holed circular slabs with same external diameter but different internal diameter, and the obtained test data are compared with the calculated data of the original formula and the new formula. The results show that the new formula greatly improves the calculation accuracy under the same conditions, its consideration of problem is closer to the facts, and its theoretical derivation is more reasonable.

Key words: Flanging force, Mathematical model, Power function hardening law, Variation in thickness