Numerical and experimental research on warm cross wedge rolling of hollow shafts with corrugated surface

HCWR (hot cross wedge rolling) of hollow shafts has been investigated while there are few investigations on CWR (cross wedge rolling) of hollow shafts at other temperatures. Because of the severe oxidative decarburization of HCWR and large deformation resistance of CCWR (cold cross wedge rolling), the WCWR (warm cross wedge rolling) was proposed for forming hollow shafts to compromise these limitations. In this paper, relevant investigations about a WCWR process of hollow shafts with corrugated surface were carried out. At first, the parameters and the geometry of the WCWR rollers of hollow shafts with corrugated surface were designed. Then, the finite element (FE) model of the WCWR process was established and verified by the laboratory test. Next, the FE results with various mandrel diameters were presented, and the influence of the mandrel diameter on the distribution of stress, effective strain, and temperature and the rolling force and torque was analyzed. Finally, the experiment results with various mandrel diameters were presented, and the effect of the mandrel diameter on the forming quality was discussed. The results show that as mandrel diameter increases, the temperature of the workpiece after rolling decreases, while the effective stress and strain and the rolling torque increase. The maximum dimensional deviation at the symmetric cross section is not larger than 0.3 mm when there is no mandrel or the relative mandrel diameter is 0.7, and the roundness is gradually worse as mandrel diameter increases.