Wall thickness uniformity of railway hollow shafts by cross-wedge rolling

Wall thickness uniformity is an important quality criterion of railway hollow shafts by multi-wedge synchrostep cross wedge rolling. The stable rolling condition of railway hollow shafts in this rolling process is analyzed,and a flattening instability criterion is presented. Based on this result,a rigid-plastic finite element model of hollow railway shafts by multi-wedge synchrostep rolling is established with DEFORM-3D software,the influence of processing parameters such as broadening angle and forming angle on the wall thickness uniformity is discussed,and the change law of wall thickness is obtained by changing these processing parameters. The bigger the forming angle,the more uniform the wall thickness is; the bigger the spreading angle,the more uniform the wall thickness is,but when the spreading angle is more than 10°,the wall thickness uniformity will decrease. A 1:5 ratio high-speed railway hollow shaft is rolled based on multi-wedge synchrostep cross wedge rolling experiment. Rolling torque measurements and wall thickness comparisons between experimental and simulated results show that the relative error is controlled within 10%,which verifies the validity of this finite element model.