Development of a low-frequency vibration-assisted drilling device for difficult-to-cut materials

In the drilling process of difficult-to-cut materials, conventional drilling has resulted in various problems such as high drilling temperature and poor machining quality. Low-frequency vibration-assisted drilling has great potential in overcoming these problems since broken chips are generated. In order to promote the application of low-frequency vibration-assisted drilling device in machining difficult-to-cut materials. In this paper, a low-frequency vibration-assisted drilling device is developed by using a novel ring flexure hinge as the elastic recovery mechanism. First, based on the theory of elastic mechanics and mechanical vibration, the stiffness of the ring flexure hinge is designed theoretically, and the influence of its structural parameters on its deflection is analyzed. And then the correctness of the theoretical design is further verified by static and dynamic simulation and stiffness test. Finally, the vibration performance of the device is tested under no-load condition, and the actual drilling test is conducted to verify the drilling performance. The results show that the device could realize the axial low-frequency vibration with constant frequency-to-rotation ratio and amplitude stepless adjustment and present good working stability under no-load and load conditions. In the actual drilling test of titanium alloy and carbon fiber reinforced plastic (CFRP)/ titanium alloy laminated structure, the device under appropriate processing parameters breaks the titanium alloy chip into small pieces and reduces the drilling temperature by 44% and inhibits the secondary damage of CFRP. It is demonstrated that the device could meet the actual processing requirements. And it also provides guidance for the design of low-frequency vibration-assisted drilling device.