EXPERIMENTAL EVALUATION OF DRAW BEAD COEFFICIENT OF FRICTION
Keywords:friction, sheet metal forming, steel sheet, tribology
In this paper the results of both friction coefficient and springback testing using a drawbead test are presented. Deep drawing quality steel sheet (DC04 according to EN 10130:2009 standard) was used as the test material. The experimental investigations were carried out using a special device that allows a change in the degree of deformation of the sheet metal on the drawbead. The friction tests were carried out for different values of tool surface roughness, specimen widths and degrees of sheet deformation. Three lubrication conditions were analysed: dry friction, machine oil lubrication and lubrication using methacrylic resin. The springback values were determined based on digital image analysis for selected friction conditions. It was found that the effectiveness of reducing the value of the friction coefficient during the pulling of a sheet on the drawbead depends not only on the lubricant used, but also on the degree of sheet deformation (displacement of the middle roll). The sheet widths influence the friction coefficient value through the character of sheet deformation during the pulling of the sheet through the drawbead.