Removal Mechanism Of Particulate Reinforced Titanium Matrix Composites In High-speed Grinding

Particulate reinforced titanium matrix composite(PTMCs)has many advantages,such as high strength,high temperature resistance and corrosion resistance,which makes it have broad application prospects in aerospace and aviation industry.However,PTMCs is a typical difficult-to-cut material.During the grinding process,the phenomenon of reinforcing particles breakage and shedding results in the serious decrease of ground surface quality.At present,some scholars have investigated the high-speed grinding force,grinding temperature and ground surface morphology of PTMCs.However,the material removal mechanism in high-speed grinding process,especially the removal behavior and influencial factors of reinforcing particles are not yet clear,which leads to the fact that the optimization of high-speed grinding process of PTMCs is lack of basic data and scientific basis.In view of this,the material removal mechanism of PTMCs in high-speed grinding is investigated by combining the finite element simulation with the grinding experiment.The material removal behavior in high-speed grinding process of PTMCs is clarified.The influence of grinding parameters and grit rake angle on the grinding force,reinforcing particle removal behavior and workpiece material stress field during grinding process are revealed.The corresponding mechanism is also discussed.The research result could give a deep understanding of the material removal mechanism of PTMCs during high-speed grinding,and it is of great significance for achieving high-quality machining of PTMCs.The main research work and achievements of the present investiation are as follows:(1)The morphology of CBN grains on the working surface of single-layer brazed abrasive wheel are characterized,meanwhile,the micro-morphology of PTMCs workpiece materials is also revealed.Furthermore,by using the model assembly technology,a geometric model of PTMCs material in high-speed grinding is established for the finite element simulation work.The simulation parameters are set,and the constitutive models and separation criteria of workpiece materials are determined.Accordingly,the finite element simulation model of PTMCs in high-speed grinding is established.(2)The accuracy of the above-mentioned simulation model is confirmed by comparing and analyzing the simulated and measured single-grit grinding force in high-speed grinding of PTMCs.Meanwhile,the influence of grinding parameters and grit rake angle on grinding force is clarified.It is found that the grinding force in the grinding process of PTMCs can be divided into two parts: one is the removal region of matrix,while the other is removal region of reinforcing particle.In the removal region of reinforcing particle,the obvious fluctuation phenomenon of grinding force is observed.(3)The influence of grinding parameters on the distribution and evolution of stress within the matrix material and the reinforcing particle during high-speed grinding of PTMCs under the grinding condition with single grit is clarifid.The removal behavior of PTMCs can be generally divided into four stages.The effect of the grit rake angle,the undeformed chip thickness and the grinding speed on the material removal behavior is revealed.Finally,a finite element simulation model of two grains is established,and the mechanism of crack formation and breakage of TiC reinforcing particles during the grinding process is clarified,which is consistent with the experimental results.