Influence of the Friction Coefficient Uniformity on the Hole Expansion Behavior

In this paper,Dynaform was used to simulate the hole expanding test,and the influence of changingfriction coefficient of the plate surface on hole expansion behavior was studied. When the friction coefficient between plate and die increases,hole expansion ratio decreases,and finally cracks in the wall of the punch occurs.Single lubrication can reduce the forming force of the test and increase the hole expansion ratio.For single side lubrication,the hole diameter will be shifted to the small side of friction coefficient.When the friction coefficient difference between the two sides is too large,it can lead to the crack in the side with the larger friction coefficient.