Thermodynamic Coupling Modeling And Characteristics Of Surface Machining Of Titanium Alloy With Hole Defects

Titanium alloys are widely used in aerospace,medical,chemical,automotive and other fields due to their high strength,low density,corrosion resistance,and high temperature resistance etc.With the widespread application of titanium alloys,people have higher and higher requirements for the machining accuracy of titanium alloy structural parts.Therefore,how to ensure the high efficiency and precision of titanium alloy cutting has become a research hotspot.However,due to the poor thermal conductivity of titanium alloys,it has become difficult to process,and the current preparation process of titanium alloys is likely to cause structural defects such as impurities,holes,and cracks in the titanium alloy.These defects not only affect the mechanical properties of the material itself,but also It will affect the stability of the cutting process and cause difficulties in the cutting process.This paper takes the hole defect as an example to study its influence on the cutting process of titanium alloy.The main research work done in this paper is as follows:(1)On the basis of the stress-strain data obtained by SHPB experiment and the J-C constitutive model obtained by LI,the five parameters in the J-C constitutive model are fitted and optimized using Monte Carlo method.The optimized J-C constitutive model fits better with the SHPB experiment.Therefore,the optimized J-C constitutive model obtains the stress value at different temperatures and different strain rates,which can characterize the stress value obtained in the experiment,which is a follow-up establishment Accurate cutting finite element model provides support.(2)Based on the above key modeling techniques,a cutting simulation model with hole defects was established,and the effects of hole defects at different positions and different sizes on the surface stress distribution,surface temperature distribution,chip shape and cutting force during the cutting process of titanium alloy were studied and analyzed.Using the Choi-Williams time-frequency analysis method to analyze the cutting force signal time-frequency,the resulting spectrogram not only verifies the correctness of the effect of different sizes and positions of defects on the cutting force,but also determines the defect location through the spectrogram The location and size,and the spectrum analysis method can provide ideas for the subsequent realization of the processing quality monitoring system and judgment of the surface processing quality.(3)The experiment was carried out using the centerless lathe test bench,and the turning experiment was carried out on the condition that the hole defect is located on the cutting path.The main cutting force value was calculated through the current value of the spindle motor measured in the experiment,and compared with the main cutting force value obtained by finite element simulation.The comparative analysis has verified the correctness of the simulation analysis.