Theoretical analysis and numerical simulation of external spline cold rolling

Cold rolling process has become an important alternative to form small module spline shafts because there are significant advantages in enhancing the mechanical properties of the component, increasing productivity, reducing production cost. However the study of spline cold rolling process is still very fewer. In the present study, the contact ratio between roller and workpiece in process of spline cold rolling is studied, which provides a theoretical basis for simplifying the analytical model and finite element (FE) model. A FE model of the external spline cold rolling process is developed under DEFORM-3D environment. Some key techniques for modelling have been proposed, such as: (1) in order to avoid magnifying slipped phenomenon, the movement system of the roller and workpiece is equivalently changed; (2) the model is treated with a cyclosymmetric problem because the geometric and processing parameters in rolling process are periodic symmetrical; (3) local mesh densification and automatic re-meshing techniques are used to improve computational efficiency and precision. Based on the slip-line field method (SLFM) and the analysis of contact state between roller and workpiece, the simplified formula of the peak value of rolling force at the infeed amount f is established. When the analytical results of rolling force are compared with FE results of rolling force, it is found that for maximal rolling force in the rolling process, the analytical predictions based on SLFM could be as reliable as the FE results.