Search

Carbon fiber reinforced polymer (CFRP) drilling operation is a very important machining process in the aerospace industries. Ultrasonic vibration-assisted drilling (UVAD) has achieved some positive effects in CFRP drilling. Because of the strong correlation between the drilling force and the hole quality, it is important to predict drilling force to optimize drilling parameters for improving the machining quality and efficiency. However, the prediction of drilling force for CFRP in UVAD is still a problem. In this paper, a mechanical drilling force model for unidirectional CFRP (UD-CFRP) in longitudinal ultrasonic vibration-assisted drilling (LUVAD) is established. In particular, the cutting lip of drill is divided into several discrete elements with different dynamic cutting characteristics. The cutting forces of different discrete elements, including the indentation force, the cutting force and the ploughing force of the cutting edge, were calculated by considering the dynamic change of fiber orientation during drilling. Then they are transformed into the thrust force and torque of the drilling process. Finally, the validity of the maximum, minimum and mean of the drilling force predicted by the model is verified through LUVAD experiments of UD-CFRP. The prediction errors of maximum thrust, minimum thrust and mean thrust can reach 14.09%, 15.72% and 8.81% respectively, and the prediction errors of maximum torque, minimum torque and mean torque are 16.20%, 18.61% and 14.96% respectively, demonstrating the validity of the model for LUVAD of UD-CFRP. In addition, the hole surface morphology of UD-CFRP under different processing conditions was compared. [ABSTRACT FROM AUTHOR]

Carbon fiber reinforced polymer (CFRP)/titanium alloy (Ti) stacks have promising application in aerospace field due to their excellent mechanical properties. During integrated drilling of CFRP/Ti stacks, the machining process at interface between CFRP and titanium alloy is very complicated. The interaction among CFRP, titanium alloy and cutting tool leads to poor processing quality, serious tool wear and other problems. In this paper, in order to deeply analyze the influence mechanism of interface area on the machining process, the research achievements and progress of drilling CFRP/Ti stacks are reviewed. Special attention is paid to the machining characteristics and CFRP damage mechanism at stack interface during drilling and helical milling of CFRP/Ti stacks. The cutting force characteristics, temperature characteristics and tool wear characteristics of interface machining are analyzed, and the damage mechanism and evaluation method are summarized. In order to solve the existing problems in drilling CFRP/Ti stacks, the suppression strategies of interface damage in recent years are discussed from four aspects: machining parameters, machining environment, tool structure and advanced machining technology. The research trend of laminated interface machining is prospected, which provides an important reference value for the realization of precision, high efficiency and low damage integrated drilling of CFRP/Ti stacks. [ABSTRACT FROM AUTHOR]