Experimental Study On Axial Ultrasound-Assisted Drilling Of Carbon Fiber Reinforced Plastics

Carbon fiber reinforced plastics(CFRP)is widely used in many fields such as aerospace,civil construction,transportation and sports goods because of its many performance advantages.CFRP is a typical hard-to-process material,which often needs to be connected with other structures in the process of use.In the process of drilling CFRP is prone to delamination,hole tearing and other hole-making defects,and the quality of hole-making is poor,which greatly limits the effective productivity.Therefore,it is of great significance to improve the quality of CFRP hole-making.Axial ultrasonic drilling technology has unique advantages in the field of hard and brittle materials processing.Its superior cutting performance can significantly reduce the cutting force and improve the quality of drilling.As one of the important special processing technologies,its research potential is self-evident.In this thesis,the drilling characteristics and experimental research of axial ultrasonic drilling CFRP are taken as the main line,and the mechanism of the action of axial ultrasonic drilling CFRP is studied,and the law of the influence of axial ultrasonic drilling on the cutting force and drilling quality of CFRP is explored.Through debugging and perfecting two kinds of axial ultrasonic drilling system,the construction of test platform is completed.The experimental study was carried out with the axial force,drilling delamination and hole wall roughness as evaluation indicators to verify the advantages of CFRP drilling by axial ultrasonic drilling and the influence of axial ultrasonic amplitude on the axial force and hole-making quality in the process of drilling.Through the mechanism analysis and a large number of experimental research and analysis of axial ultrasonic drilling CFRP,obtain that: 1.Through the kinematics analysis of axial ultrasonic drilling and the study of cutting mechanism of CFRP,the relationship between dynamic cutting speed and amplitude of velocity variation and parameters is analyzed,the cutting form of CFRP under different cutting direction angles is qualitatively summarized,and the main cutting edge is deduced and established.The calculation method of macro-axial force is based on the average axial force,and the mechanism of reducing the average axial force is qualitatively analyzed in the theory of impact characteristics.2.Through drilling tests,it is found that the axial force is obviously reduced by the axial ultrasonic drilling.The main and secondary contributions of drilling parameters to the axial force are feed,amplitude and rotational speed,and the drilling axial force follows the drilling axial force.Axial ultrasonic drilling can achieve smaller delamination,and the delamination factor of CFRP outlet decreases with the increase of axial ultrasonic amplitude.The larger the amplitude,the smaller the delamination factor.4.Axial ultrasonic drilling can reduce the roughness of the hole wall and obtain better shape of the hole wall.With the increase of the amplitude,the overall surface quality of the hole wall presents a good trend.