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 this paper, a low-frequency vibration-assisted drilling device is developed by using a novel ring flexure hinge as the elastic recovery mechanism. Firstly, based on the theory of elastic mechanics and mechanical vibration, the deflection of ring flexure hinge is designed theoretically, and the influence of its structural parameters on its deflection is analyzed. Then, the correctness of 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 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 titanium alloy chip into small pieces and reduces drilling temperature by 44% and inhibits secondary damage of CFRP. It provides the reference and guidance for the development of LFVAD device in presented work.