Papers by Keyword: Cold Metal Forming

Abstract: The present paper investigates the evolution of the WC grain size and morphology with the number of produced parts. Four reduction dies used in cold forward extrusion of steel are taken from the production line: a brand new die and three dies which have respectively produced 100.000, 150.000 and 220.000 parts. 3D roughness measurements and SEM micrographs are performed on the contact surface of each die. Results of these analyses highlight that WC grains are subject to plastic strain and are removed from the surface as the number of produced parts increase, leading to a growth of WC free areas where steel adhesion may occur. When analyzing the size of the WC grains, it appears that the population of small grains increases with the number of produced parts until 150.000. Then the population of small grains decreases. A wear mechanism is proposed to explain this variation of WC grains size with the number of extruded parts.

Abstract: It was impossible to obtain the transverse friction along the strip width in most previous studies of cold strip rolling because the surface roughness lays were assumed to be vertical to the rolling direction. In this study, several types of oblique roughness textures were manufactured on aluminum samples and compression tests were carried out to obtain the effect of different textures on the deformation behavior of surface asperity. Different surface textures resulted in very different peak value of stress. It was found that stress was high and changed dramatically at the initial compression stage but tended to be stable when the total reduction increased. The asperity of which the top angle is 160° showed relatively high resistance to deformation.