Study On Cutting Force And Tool Wear Of Rotary Ultrasonic Hole Machining On SiC

SiC engineering ceramics have the characteristics of high hardness,high brittleness,high elastic modulus,high compressive strength,and low tensile strength,which are widely used in aerospace,integrated circuits,and armor protection.Due to its high hardness and brittleness,it is difficult to guarantee the machining quality because of the serious tool wear and defects such as cracking and chipping during mechanical processing.In view of this,a new type of thin-walled diamond trepanning bit and rotary ultrasonicassisted machining technology was used to conduct hole processing tests and mechanistic studies.The main research contents are as follows:(1)The kinematic characteristics of rotary ultrasonic machining of SiC engineering ceramics were analyzed,and the cutting force prediction model of the process was established in combination with the indentation fracture mechanics test,and the rotary ultrasonic assisted machining technology and the new thin-wall diamond trepanning bit were used to carry out the hole machining test of the workpiece.By comparing the cutting force of drilling and the mathematical model of cutting force established in the process of hole machining,the average error rate of the mathematical model established is verified to be 13.4%.(2)Based on JH-2 constitutive model,a three-dimensional finite element simulation of rotary ultrasonic nesting drilling for SiC engineering ceramics was carried out to analyze the influence of different process parameters on the simulation results.Based on the data of the rotary ultrasonic test,it is concluded that the error of the cutting force model obtained by 3D finite element simulation is less than 30%,and the overall fit is high.(3)Describes the preparation of a new type of thin-wall diamond trepanning bit,analyzes the factors that affect tool wear and the mechanism of tool wear,and explains in detail the shape of tool wear and the causes of each shape;The experimental study on tool wear shows that the tool wear increases with the increase of spindle speed and feed speed.On the whole,when ultrasonic is added,the tool wear ratio also decreases,with the average wear ratio reduced by 21.3%.(4)The difference in pore wall micro-appearance between conventional and ultrasonic machining conditions was studied;The influence of test parameters on the morphology of ceramic inlet and outlet was analyzed,and the influence and law of each process parameter on the outlet collapse and the roughness of the inner wall of the hole were studied.The results showed that ultrasonic-assisted machining reduced the edge breakage and hole wall roughness by 7.6% and 24.1% on average,respectively.Through the above study,the material removal mechanism and kinematic characteristics of rotary ultrasonic-assisted machining of SiC engineering ceramics were clarified,the cutting forces of the new thin-walled diamond trepanning bit for rotary ultrasonic hole machining were modeled,and the finite element simulation of the process was performed to reveal the influence of different machining parameters on tool wear and surface quality,which provides a reference for the high quality and high-efficiency hole machining of SiC engineering ceramics.