Lin Jieqiong

Tool path generation for fabricating optical freeform surfaces by non-resonant three-dimensional elliptical vibration cutting:

Optical freeform surfaces on difficult-to-machine materials are used widely in a range of areas such as optical engineering, semiconductor and biomedical products. However, it is a challenge to achieve both a high surface quality and complex surface shape because of their tendency of being damaged in brittle fracture in the machining process. In this article, non-resonant three-dimensional elliptical vibration cutting method is proposed to obtain optical freeform surfaces of some difficult-to-machine materials, which is realised by making the diamond tool vibrate at a three-dimensional ellipse in the non-resonant manner. The elliptical motion parameters of this method can be taken active control under different machining conditions, which can make us get optimal cutting performance. Based on this new elliptical vibration cutting method, the algorithm of the tool path generation considering the tool arc radius compensation is proposed, which can avoid excess turning. The three-dimensional surface topography prediction model is established to verify the tool path. Simulation analysis on a typical optical freeform surface, toric surface, has shown that the tool path generation algorithm with the proposed elliptical vibration cutting method can envelope the toric surface, which has illustrated the validity of the proposed algorithm and technique. The tool path generation algorithm can be used to direct one to machine the optical freeform surface in the cutting experiments.

Development of nonresonant elliptical vibration cutting device based on parallel piezoelectric actuator

Because of its unique intermittent cutting and friction reversal characteristics, elliptical vibration cutting (EVC) has become the most promising method for machining of otherwise difficult-to-machine materials in recent years. However, some problems remain in the research towards development of EVC devices. In this paper, with the intention of solving the existing problems of EVC devices, a nonresonant-type EVC device that is driven by two parallel piezoelectric stacks is developed. After the principle of the device is introduced, the stiffness of the EVC device is calculated, and device simulations and experimental evaluations are performed. In addition, the performance of the EVC device is also tested. The experimental results show that the maximum strokes of the two directional mechanisms operating along the X- and Z-axes can reach 16.78 μm and 15.35 μm, respectively, and the motion resolutions in the X-axis and Z-axis directions both reach approximately 50 nm. Finally, a curved surface cutting exper...