Finite element analysis of deformation characteristics in cold helical rolling of bearing steel-balls

CAO Qiang(曹强)^{1, 2}, HUA Lin(华林)^{2, 3}, QIAN Dong-sheng(钱东升)^{1, 2}

(1. School of Materials Science and Engineering, Wuhan University of Technology, Wuhan 430070, China;
2. Hubei Key Laboratory of Advanced Technology of Automotive Parts (Wuhan University of Technology)
Wuhan 430070, China;
3. School of Automotive Engineering, Wuhan University of Technology, Wuhan 430070, China)

Abstract:Due to the complexity of investigating deformation mechanisms in helical rolling (HR) process with traditional analytical method, it is significant to develop a 3D finite element (FE) model of HR process. The key forming conditions of cold HR of bearing steel-balls were detailedly described. Then, by taking steel-ball rolling elements of the B7008C angular contact ball bearing as an example, a completed 3D elastic-plastic FE model of cold HR forming process was established under SIMUFACT software environment. Furthermore, the deformation characteristics in HR process were discovered, including the forming process, evolution and distribution laws of strain, stress and damage based on Lemaitre relative damage model. The results reveal that the central loosening and cavity defects in HR process may have a combined effect of large negative hydrostatic pressure (positive mean stress) caused by multi-dimensional tensile stresses, high level transverse tensile stress, and circular-alternating shear stress in cross section.

Key words:cold helical rolling; finite element (FE) simulation; rotary forming; bearing steel-balls