Research On The Adiabatic Shear In Serrated Chips Formation Based On Cutting Simulation

Titanium alloys are commonly used in the aerospace and automotive structures. However, some problem such as poor thermal conductivity properties, low elastic modulus and high chemical affinity, occur during the cutting process. Thus, high partial cutting temperature, vibration caused by bending deformation, serious tool wear affects the surface accuracy. Based on the machining features of titanium alloys, in this paper, the simulation and experiment were combined to study serrated chips mechanism of the titanium alloys and adiabatic shear deformation in-depth, so as to understand the cutting mechanism more and improve the machining quality of the titanium alloys.The finite element model of Ti6Al4V alloy was simulated by the commercial software DEFORM-2D.The variation of the temperature in the cutting process under different cutting conditions was analyzed to obtain the influence of different cutting parameters on the serrated chips morphology. Beside of them, the distribution and deformation rules of the effective stress, the effective strain and the effective rate were analyzed according to simulation at different fracture criterion parameters.In order to obtain appropriate parameter and for material model of the fracture criterion on the serrated chips formation in Titanium alloy machining and for Fundamental method of simulate cutting of difficult-to-machine materials.4sets of different fracture criterion parameters were put into its database to simulate the chip formation process. The metallographic chip specimens were carried out under the same experimental cutting conditions.The simulation results and experimental results of micro geometric morphology via SEM were quantitative compared. When fracture criterion parameter was200, their relative error was the least. Then, the appropriate theoretical parameter of the fracture criterion in cutting simulation was acquired.This paper start at introduction covers microscopic characteristics of deformed shear band and transformed shear band. Both the two types of the adiabatic shear band through microstructure observation inside adiabatic shear band of the titanium alloy’s serrated chips. The influence of different cutting speed, feeding speed on the serrated chips morphology was also researched. As the cutting speed increased, feeding speed increased, the formation and development of the transformed shear band inside adiabatic shear band of the titanium alloy’s serrated chips will be prompted. In order to study the deformation inside adiabatic shear band for serrated chips, the deformation degree of adiabatic shear band was characterized with the shear strain γs and shear strain rate γs., Analytical formulas of shear strain and shear strain rate were derived through geometric characterization chart of serrated chips formation. And the outline geometrical sizes of serrated chips under different cutting speed were measured by metallographic microscopic image analysis system. The calculation results show that the deformation degree of adiabatic shear band of serrated chips increased with increasing the cutting speed raged from50m/min to200m/min.