Experimental investigation of Teflon-pad forming on circular metal blanks using a concave die

This article studies on Teflon-pad forming process of circular metal blanks using a concave die by the experimental method. Influences of material type and thickness of sheets, depth and width of ring groove of the die and thickness of Teflon-pad on the forming process are investigated. For this purpose, several dies with different depths and widths of groove are machined from hardened steel. Some blanks were prepared from galvanized iron with thickness of 0.6 mm and the others were prepared from two different aluminum alloys with different thicknesses of 0.6, 1.1 and 1.5 mm. Blank is a circular sheet with diameter of 60 mm. Solid cylindrical Teflon pads with different thicknesses of 13, 15 and 23 mm are used in different tests. Blank is placed on a rigid die with a certain ring groove and solid cylindrical polyurethane Teflon is placed on top surface of the blank. Then, the mentioned system is placed between two rigid platens. During the test, punch moves with a constant velocity and polyurethane Teflon is compressed; so, the blank is shaped into desirable product. Experimental results show that when groove width of the die enhances, bending radius of a part of blank that is over the groove increases; so, required load for the forming process decreases. Also, the measurements indicate that at a certain punch displacement, required load for the forming process of thicker blanks are less than thinner one, and, created deformations in thicker samples are less than thinner blank.