Experimental study of the effects of rough texture on surface deformation during cold metal forming
Both longitudinal and transverse frictions arising from plane strain during cold metal forming are of crucial importance for the accurate modelling, optimum design, and control of industrial processes. However, the influence of the friction and roughness along the transverse direction has been neglected in much previous research. Oblique roughness textures are considered, and the scale of roughness asperities is enlarged in this study. Four types of prism patterns, in which the angles between the longitudinal direction and the top line of prism are 90°, 60°, 30°, and 0°, and three types of pyramid patterns, in which the top angles are 151.9°, 161.1°, and 168.6°, were designed and manufactured using samples of annealed Al 6060T5. All compression tests were completed in 10 passes, and the total displacement of the pressure head was 5.4 mm. The first five passes were carried out on an Instron 8033 Materials Testing Machine, and the last five passes on a 500-ton compression-testing machine. The surface morphologies of the deformed peak were analysed, and the top areas of the deformed peak were measured. The effects of the angle between the longitudinal direction and the top line of the prism texture or the top angle of the pyramid texture on the surface morphology of the deformed peak are not obvious. The angles have a relatively significant effect on the deformation behaviour of the surface layer during cold metal forming when the deformation is small. The pattern with a top angle of 161.1°, which is the closest to the real value, shows the highest deformation resistance when the displacement of the pressure head is less than 1.2 mm.
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