Research On Milling Force Model Considering Dynamic Characteristics Of Cutter For Ruled Surface Blades In Five-axis Flank Milling

Milling force model and milling system dynamics model are the theoretical basis and prerequisite for analyzing milling state,predicting stability,studying surface topography simulation and error compensation,and establishing and optimizing reasonable cutting parameters.The five-axis finishing flank milling process of the ruled surface blades has the characteristics of large tool overhang,large distortion in geometrical profile,resulting in a decrease in tool and workpiece rigidity.Therefore,ignoring the dynamic characteristics of the tool and milling system,the establishment of milling force and dynamic models in the ideal case,the result is not easy to make an accurate prediction and may expand the deviations in follow-up researches.So it is necessary to study the dynamic characteristics of milling cutter and system for ruled surface blades in the five-axis flank milling process,and to establish the milling force model and dynamics model,which can better reflect the actual machining situation.Firstly,the milling force coefficient model and the method of parameter identification were established.By analyzing the contact areas between milling cutter and workpiece,the parameters such as the start and exit radial immersion angles and the axial position range of the model were determined.The three instantaneous milling force components were measured by the designed milling experiment and the average value was calculated,then the edge-specific coefficients and shear-specific coefficients in three directions were obtained with the milling force coefficient model.Secondly,a five-axis instantaneous milling force model considering cutter runout was established.Based on the geometrical description of cutter runout and the definition of undeformed chip thickness,geometric analysis and matrix transformation were carried out with the aid of the established coordinate system.The chip thickness model considering cutter runout was deduced by vectorcalculation.According to the undeformed chip thickness model,the milling force modeling of ruled surfaces was carried out in five-axis flank milling,and the parameters’ identification method of cutter runout in this model is given.Based on the established model,the simulation results of milling force,undeformed chip thickness and effective cutting radius are given,and the simulation results of different cutter runout parameters are compared and analyzed theoretically.Thirdly,a five-axis instantaneous milling force model was established,which considers the influence of cutter deflection.The cutter deflection model was defined by the cantilever beam structure,which was added to the calculation of the undeformed chip thickness.Then,the milling force model was established,which considers the deformation of tool in five-axis flank milling.And the finite element software ANSYS was used to simulate the deformation of the ball-end milling cutter in the flank milling.The deformation data of angular and axial positions,the overall deformation characteristics of the milling cutter in one rotation period were obtained,while the simulation results were analyzed theoretically.Finally,the dynamic model of double flexible milling system was established.Based on the dynamic model of flexible tool and the dynamic model of flexible workpiece,the dynamic characteristics of tool and workpiece were analyzed synthetically.And a dynamic model of double flexible system with multi-degree of freedom considering tool-workpiece coupling was established.The dynamic undeformed chip thickness model and the milling force model under the influence of the dynamic displacement response of the system were proposed,according to the theory of the dynamic response of the double flexible system and the effect of the chip thickness.The dynamic displacement and the milling force of the system were simulated and analyzed respectively.Compared with the experimental data of the ruled surface impeller in flank milling process,the comparison results show that the established model has good consistency and accuracy.