Research On Residual Stress Of Cold Roll-beating Forming Workpiece

Cold roll-beating forming technology is an energy conservation and near-clear shaping method which using of certain plastic deformation ability of natural temperature,while using certain shape and high-speed roller rotation beating workpiece surface continuously,forcing surface-layer metal local flowing then generating plastic deformation.In the cold roll-beating forming process,the surface residual stress of the workpiece will lead to stress concentration and surface cracks,which will affect the surface accuracy and fatigue life of the workpiece.In order to understand and master the distribution of residual stress in cold roll-beating surface layer of workpiece.,and can accurately predict the formation of surface residual stress as the goal,this paper focusing on the formation mechanism of residual stress in cold roll-beating process and the influence of process parameters and material parameters on the residual stress distribution are studied.Based on the forming principle and characteristics of cold roll-beating forming,the cause of residual stress in cold roll-beating process is analyzed.It is pointed out that the most important factor affecting the fatigue life of the workpiece is the residual compressive stress.and the residual stress elimination method is presented when the residual stress in the workpiece exhibits tensile stress.A finite element dynamic and static simulation model is established by ABAQUS software.Firstly,the distribution of Mises force on the workpiece surface was obtained by dynamic simulation at different speeds,penetration and material characteristics.Because inner force of workpiece in result of dynamic simulation is at unbalance state,it cannot directly solve the residual stress,so the static simulation model is established on result of dynamic simulation,and the distributions of residual stresses in tangential,axial and radial directions at different speeds,rolling depth and material properties is determined by static analysis.The variation trend of residual stress on the surface and depth of the workpiece was analyzed.Experiment on self-developed cold roll-beating equipment,build experimental platform for residual stress measurement,and study on residual stress of cold roll-beating.The distribution of the tangential residual stress along the depth direction is obtained by the measurement of the workpiece under different rotational speed and penetration depth,the comparison between the experimental results and the finite element simulation results shows that the residual stress variation has a good consistency,which verified effectiveness correctly of the simulation model.