Research On The Milling Stability Of The Cradle-Type Five-Axis Machine Center

The five axis machining technology is widely used in the field of mechanical process.In this paper,the vibration problems of the milling plane issues in the five axis machining center are studied.The chatter prone sites are determined by the dynamic characteristics analysis of the main structures of the five axis machining center.And the milling forces of three directions of the vertical milling cutter are calculated and simulated.According to the force analysis of the spindle system,the milling stability lobe diagrams are drawn.The vibration tests of the spindle system prove that the milling stability lobe diagrams can effectively prevent the occurrence of flutter.The influences of different milling parameters on the milling vibration are also analyzed by the vibration tests of the spindle system.Firstly,a 3D model of the five axis machining center is drawn.And the 3D model of the five axis machining center is simplified.According to the results of the modal analysis and the harmonic response analysis of the simplified 3D model,the main deformation parts of the five axis machining center are determined.Secondly,the prediction methods of the three direction milling forces of the milling process of the aluminum alloy work piece are studied.And a new milling force prediction model is established.The milling force model takes into account the cycloid trajectory of the vertical milling cutter,the temperature of the milling area,the constitutive relation of the aluminum alloy,and so on.The finite element simulation results of the milling forces with different milling parameters are analyzed.At the end of this section,the prediction extreme values of the milling forces are compared with the simulation extreme values of the milling forces.Thirdly,based on the milling force prediction model,a prediction model of the dynamic milling force is established.The chatter stability lobes are calculated by the semi-discrete algorithm and the prediction model of the dynamic milling force.The modal tests are carried out on the spindle of the five axis machining center and the modal parameters are extracted.The characteristic curves of the frequency response function and the chatter stability lobes are drawn by software.The effects of the feed engagements,the number of milling edges and the selected milling methods on the milling stability are analyzed.Finally,the vibration experiments of the different milling parameters are designed.The influences of the different milling parameters on the vibration experiments are studied by the control variable method and the analysis of acceleration signal.And the influences of the different milling parameters on the chatter of the spindle system are also analyzed.