Numerical and experimental investigation on material flow in gear forced throughfeed rolling process

Abstract

The cylindrical die forced throughfeed rolling process for gears was proposed to overcome an end-effect behavior of the standard radial-feed gear rolling process which can result in pitch variation and excessive axial end-flow. In the rolling process, the workpieces are pushed through the gap of the rolling tools to form the gear teeth. Understanding of material flow is important for grasping the cause of defect formation and improving the quality of formed gears. In this paper, the material flow behavior of the gear forced throughfeed rolling process was studied on the flow velocity and displacement of key locations by using finite element analysis (FEA). The experiment was also conducted and its blank was sliced to thin pieces, and the grid pattern (GP) was utilized to track the trajectory of flowing materials. The results show that the end-flow is located at the root rather than the tooth crest of the formed workpiece, because the compressive forces from rolling tool mainly take effect at the root of the formed workpiece. The asymmetry of circumferential flow displacements with respect to the gear teeth results in the asymmetrical flanks defect, and this is due to the meshing between teeth of rolling tool and workpiece. The local displacement in the radial direction is larger than that in the circumferential direction.