Experimental Study Of Low Frequency Axial Vibration Sleeve Hole Machining For Ceramics,FRP And Their Laminate Composite Components

The protection and mobility of special vehicles are increasingly demanded in modern warfare.Engineering ceramics,fiber reinforced plastic?FRP?and their laminated composite components have low density and high specific strength.They are excellent materials for high performance light armor and play an increasingly important role in the field of armor protection.Due to the restriction of forming technology,secondary hole processing is inevitably needed in the process of mutual assembly of protective armor.Engineering ceramics and FRP are typical hard-to-machine materials with different machinability,especially for their laminated composite components.Solving the processing problems of these high-performance protective materials is conducive to their application and development.This paper combines the diamond drill bit sleeve processing technology with the low frequency axial vibration processing technology,and carries out the hole processing experiment on engineering ceramics,FRP and their laminated composite components.The main contents are as follows:?1?Based on the processing characteristics of engineering ceramics and the indentation fracture mechanics model,the mode and cause of crack formation and propagation of ceramic materials are analyzed.With scanning electron microscope?SEM?,the material removal methods of Al₂O₃ engineering ceramics are studied from the microscopic point of view.For discussing the causes of delamination and fiber tearing at the entrance and exit of FRP,the material processing characteristics of GFRP are introduced,and the processing defect model of entrance and exit is established.The trajectory of a single abrasive particle in the process of low-frequency axial vibration sleeve processing is analyzed,and the technological characteristics of low-frequency axial vibration processing are discussed.?2?Based on the machined characteristics of engineering ceramics and FRP,a thin-walled diamond trepanning bit with sintering-brazing composite technology is developed by designing the structure,composition,diamond abrasive grade,particle size,concentration and process flow of the bit.The new bit is used for trial processing of Al₂O₃ engineering ceramics,and the wear forms and characteristics of abrasive particles,end face and side face of the bit are observed and analyzed by SEM.It is verified that the new thin-walled diamond drill bit can realize constant speed feed processing of Al₂O₃ engineering ceramics,and the service life is ideal.?3?Low-frequency axial vibration drilling experiments are carried out on Al₂O₃engineering ceramics,GFRP and their laminated composite components by using the new thin-walled diamond drill bit.The influence of low frequency vibration process on the processing quality of Al₂O₃ engineering ceramics and GFRP holes is investigated by changing the vibration amplitude.Taking drilling axial force as evaluation index,the influence of processing parameters on drilling axial force is analyzed by orthogonal test method,and a better factor level scheme is obtained.The causes of processing defects such as bottom degumming and exit burns in hole processing of Al₂O₃ engineering ceramics/GFRP laminated composite components are analyzed.