Study On Grinding Force And Subsurface Damage In Single Abrasive Particle Grinding Process By Theoretical Analysis And Simulation

Brittle materials such as optical glass and engineering ceramics with high mechanical properties and structural properties such as high strength,high temperature resistance and excellent corrosion resistance,has been widely used in the fields of semiconductor,medical and microelectromechanical systems and so on.However,due to the characteristics of the high hardness and brittleness of brittle materials,the effective processing methods and processing cost control are the difficult problems in the application of brittle materials.At present,grinding is the most effective method for machining brittle materials.In order to obtain the good surface integrity of brittle materials with the high efficiency and low damage,this thesis systematically investigates the interaction between abrasive particle and workpiece in the grinding process of brittle materials.Based on the theory of single abrasive particle grinding and indentation fracture mechanics,a theoretical model for predicting the grinding force of single abrasive grain and subsurface damage during the grinding process of brittle materials is established,and the influence of grinding parameters on the grinding force and subsurface damage is analyzed in depth.In addition,the finite element simulations are implemented that is conducted to verify the correctness of theoretical analysis.The main achievements and innovations of this thesis are as following:(1)Based on the theory of single abrasive particle grinding,the mode of the material removal in the grinding of brittle materials is analyzed,and a prediction model for the grinding force of single abrasive particle is established.The theoretical expression of the grinding force of single abrasive particle and grinding parameters in grinding process of brittle materials is proposed and the influences of grinding parameters on the grinding force of single abrasive particle are revealed.In addition,according to the contact relationship between abrasive particle and workpiece in ultrasonic vibration assisted grinding,the grinding modes of abrasive particle are analyzed.A prediction model for the grinding force of single abrasive grain in ultrasonic vibration assisted grinding is obtained and the effects of different vibration parameters on the grinding force of single abrasive grains are also discussed.The theoretical results indicate that increasing the grinding depth and the workpiece speed will increase the material removal volume per unit time,so that the grinding force of each abrasive particle increased in the grinding process of brittle materials.Increasing the grinding speed will increase the total amount of abrasive particle involved in the grinding process per unit time and reduce the penetration depth of the abrasive particle during grinding process,so that the grinding force of each abrasive particle decreased,which is also conducive to improve the efficiency of the grinding process of brittle materials.At the same time,increasing the amplitude and frequency of ultrasonic vibration,which is equivalent to increasing the trajectory length of the abrasive particle and reduces the penetration depth of the abrasive particle during the grinding process,resulting in the grinding force of the single abrasive particle decreased.(2)Based on the indentation fracture mechanics,the theoretical analysis model of the subsurface damage depth of single abrasive particle in grinding process of brittle materials is established,and the comprehensive influences of lateral cracks and medium cracks on subsurface damage depth are discussed in detail.In theoretical analysis model for subsurface damage depth,the rotation of the abrasive particle along with the wheel is considered and the effects of grinding parameters on the rotation angle are also analyzed synthetically,and reveal the influence of different grinding parameters on subsurface damage depth of workpiece.The theoretical results show that decreasing the grinding depth,and increasing the grinding wheel diameter and the ratio of the grinding speed to the workpiece speed,the subsurface damage depth in brittle material grinding decreases.(3)Based on the finite element method,a simulation model is established to analyze the grinding process of single abrasive particle.In the finite element simulation,the modes of material removal in brittle material grinding and the distributions of subsurface cracks on the workpiece surface are fully reflected.The results show that the conclusions obtained in the finite element simulation are consistent well with the theoretical prediction results,which confirms the correctness of the theoretical analysis model and the rationality of the finite element simulation.The results are meaningful and helpful in selecting the reasonable grinding parameters to obtain a good surface quality in brittle material grinding.