Study On Multidirectional Cutting Characteristics And Methods For Shaft Parts

As the most common machining object in mechanical engineering,shaft parts play an important role in automotive and aerospace engines,such as crankshafts,disk shafts and aero shafts.The manufacturing process of shaft parts usually experiences a cutting process.Due to the multiple features and complex structure of shaft parts,there are problems such as multiple clamping,difficulty to shape in one go and many tool idling,causes inefficiency in energy consumption,low processing efficiency,deviations in part dimensions,etc.To solve the comprehensive problems of the current cutting process.The multidirectional machining methods of forward and reverse multidirectional cutting(MDT)and parallel multidirectional cutting(P-MDT)were presented in this paper,and a combination of finite element simulation and orthogonal dry cutting experiments was used to investigate the cutting mechanisms and process performance of multidirectional cutting.The process advantages of multidirectional cutting were demonstrated by comparing multi-case cutting of 45 steel shaft parts with the unidirectional cutting(UDT)method.The main research contents of this paper include the following aspects:(1)The concept and processing principle of MDT are introduced,the mechanism of MDT is revealed,and the optimization of multiple machining schemes for MDT is implemented in conjunction with the finite element method.First,the differences in toolchip contact conditions between MDT in different machining directions are analyzed,and the influence mechanism of the tool cutting edge angle and end cutting edge angle on the cutting characteristics of MDT is revealed.Then,the thermomechanical coupling model of MDT is constructed in the ABAQUS,and the material behavior under large strain is described based on the Johnson-Cook(JC)constitutive model.Three MDT machining schemes with tool cutting edge angle of 105°,115° and 125° and end cutting edge angle of 40°,30° and 20° are established.Finally,cutting forces,cutting temperatures,shear zone stresses and chip morphology are used as performance evaluation indexes,concluding that the MDT machining scheme with tool cutting edge angle of 115° and end cutting edge angle of 30° has better integrated cutting performance.(2)The influence mechanism of cutting parameters on the cutting characteristics of MDT is revealed.The experimental platform of cutting force and temperature based on the principle of natural thermocouple and charge amplification method is established,and a four-level dry orthogonal cutting experiment with three factors is designed.The experimental results show that the cutting characteristics of forward and reverse cutting are different.The influence mechanism of cutting parameters on the cutting force,cutting temperature and surface roughness of MDT is revealed by the S/N analysis of the smallerthe-better characteristics.The simulation results are in good agreement with the experimental values.The wear of the rake and relief tool faces of the MDT tools is observed by scanning electron microscopy,and the relief tool faces show more obvious scratches.(3)A comparative study of the process performance of MDT versus UDT is carried out and the process advantages of MDT for shaft parts are revealed.The energy consumption characteristics,cutting time characteristics and cutting residual area of MDT and UDT are compared and analyzed,and the energy efficiency factor and machining efficiency factor of MDT are established.A case study of three typical shaft parts is carried out to compare the energy consumption,cutting time,surface roughness and chip morphology of MDT and UDT.The energy consumption for MDT is reduced by 10.88%,7.25% and 9.52%,and the cutting time is reduced by 6.40%,8.45% and 7.76%respectively,while the surface burr is reduced,and the roughness is lower.The reverse cutting of MDT can cut off the chip accumulation of forward cutting,avoiding the chip accumulation causing entanglement phenomenon.Besides,the reverse cutting produces a higher degree of chip curl,clockwork and short c-shaped chips occur when the depth of cut increases,with better chip removal and chip breaking effect.(4)The concept and processing principle of P-MDT are introduced and the cutting characteristics of P-MDT in multiple material removal patterns are investigated by finite element methods.The three-dimensional motion model of P-MDT is developed,and multiple material removal patterns under the variation of cutting parameters and spatial parameters are established.The thermomechanical coupling model under P-MDT with multiple material removal patterns is established in ABAQUS,and the results of cutting force,temperature,shear zone stress and chip morphology are obtained.Compared with the MDT,the cutting force and cutting temperature are reduced to a certain extent in the shared cutting surface pattern due to the overlapping of the cutting surfaces.The difference in cutting speed of the dual tools in the non-shared cutting surface pattern has a difference on the cutting force and cutting temperature.