Study On The Forming Characteristics Of GH4169 Sawtooth Chip Under High Pressure Cooling

Nickel-based superalloy are characteristically difficult to work with and are prone to high cutting forces and high cutting temperatures during machining,resulting in the formation of serrated chips,the process consumes energy to total energy consumption is relatively high,and causes high-level vibration of the cutting force,which seriously reduces the operating life of the tool and the worked surface quality of the workpiece.High-pressure cooling,as a new form of machining technology,can effectively reduce the cutting temperature,improve the chip breaking ability and plays an active effect in the cutting process.In this paper,through cutting Nickel-based superalloy GH4169 under high pressure cooling test,the characteristics of serrated chip generation under high pressure cooling are carried out,and the energy dissipation characteristics during high pressure cooling cutting process are analyzed,which is of great significance in improving tool life,machining accuracy and reducing the loss of energy.Firstly,the finite element software ABAQUS are used to simulate the cutting of nickel-based superalloy using PCBN tools at high pressure cooling,to analyse the chip characterisation during the formation of serrated chips at different cooling pressures and cutting parameters,to conduct a preliminary discussion on the causes of the adiabatic shear zone,and to explore the changes in the temperature and strain fields inside the adiabatic shear zone at different cooling pressures and cutting parameters.Secondly,through turning nickel-based superalloy test,chip is taken and metallographic sample is prepared,and then compares with finite element simulation to analyze the sawtooth degree and sawtooth frequency and step of sawtooth formed under conventional cooling,dry cutting,high pressure cooling(different pressure values)and different cutting parameters.The formation characteristics of chip burr is observed,the frequency and height of chip burrs and their effect on PCBN tool wear are investigated;the principle of serrated chip formation during PCBN tool cutting is studied and the qualitative mechanism of the adiabatic shear zone is analysed;the evolution of the adiabatic shear zone and the geometrical characteristics of the adiabatic shear zone are investigated and the trends in strain and strain rate are analysed accordingly and the simulated results are the subject of comparison.At last,The energy dissipation model and adiabatic shear zone energy model are established to study and analyze the plastic deformation energy of the machined surface during the sawtooth chip formation under high pressure cooling.By analysing the impact energy,the plasticity of the first deformation zone,the friction energy of the tool-chip contact surface and the kinetic energy of the chip,the energy dissipation under different cutting conditions is contrasted and the influence of different cooling pressures and different cutting parameters on the energy dissipation during the formation of serrated chips are explored.