Numerical study on cold extrusion of gears varying the extrusion shoulder geometry

Abstract

Abstract. Cold forging processes, such as cold extrusion and in particular the Samanta process, provide a considerable potential for improvement in gears production. The method behind the Samanta process is based on the principle of cold extrusion in stacks. After partial forming of a workpiece, another workpiece is inserted into the die in order to eject a completely formed gear in the direction of the punch movement. Although this operating principle offers great potential for high-volume production, the industrial relevance of this process is limited by disadvantages such as high tool loads, limited gear accuracy and deformations on both face ends of the gear wheel. In order to overcome the technological challenges associated with the Samanta process, the die geometry was adapted. In this case the die operating surface was modified in terms of an extended forming zone length combined with an undercut in the tooth cavities of the die. In this paper the numerical results for this novel process regarding the correlations between geometric die parameters and resulting process data, such as punch force, contact pressure and die filling, are presented. The spline-based tool was methodically varied between one linear and two square (concave, convex) designs and was numerically evaluated using Deform 3D™ software.