Experimental evaluation of value of friction coefficient in the drawbead region

Drawbeads are supposed to change the stress state o f sh ets in specific areas of the sheet material, or compensate for material flow at the periphery of the drawpiece, especially when forming complex shaped thin-walled products. The article presents the results of frictional resistance testing of a D C04 steel sheet using a drawbead simulator test. Experimental investigations were ca rried out using a special device that allows a change in the degree of deformation o f the sheet metal on the drawbead. Specimens were tested for: (i) three degrees of sheet deformation; (ii) three countersamples’ surface roughness; and (iii) three lubrication conditions: dry friction, machine oil lubrication and paint lubrication . The test specimens were cut out along, and transversely to, the direction of rollin g of the sheet metal. The basic relations between technological parameters of frictio n est and coefficient of friction were determined.