Friction analysis of microcosmic elastic-plastic contact for extrusion forming

In extrusion forming process, according to elastic-plastic contact between microcosmic rough surface of tool and workpiece, elastic-plastic contact model was founded and then real contact area, normal stress and normal deformation value were calculated in accordance with Hertz theory. Based on adhesive friction theory, the paper analyzes the formation mechanism of surface friction in extrusion process, and researches the relationship between friction coefficient and geometrical parameters of rough surface: tangential slope angle of asperity θ, the radius of asperity R2 and the maximum height of asperity h. The interpretation of results shows that θ mostly affects friction coefficient, R2 has little effect on friction coefficient and h has no effect on it. The results can guide the design of extrusion technology and the analysis of die life.