Research On The Key Techniques Of The Vibration-assisted Cutting For Micro/Nano-Structured Functional Surface Fabrication

Micro/nano-structured functional surfaces can enhance the functionality and performance of industrial components,and are widely used in various fields including optics,solar energy technology,information technology,bio-engineering and so on.Currently,it is still a challenge to efficiently and flexibly fabricate the complex micro/nano-structured surfaces by conventional mechanical and non-mechanical manufacturing methods.To promote the broad applications of the micro/nano-structured surfaces,a vibration-assisted cutting method is proposed and studied both theoretically and experimentally in current study.Basic working principle,toolpath generation strategy,material removal mechanism and surface topography model for this vibration-assisted cutting method are comprehensively investigated and verified by machining experiments to provide a solid basis for practically implementing this new technique.The following innovation works have been completed:A vibration-assisted surface texturing method is proposed to generate complex micro surface textures both on the cylindrical surface and the face surface of a cylinder.Then,the working principle of this vibration-assisted surface texturing method is analyzed.Based on the kinematics of the cutting process,the effects of the cutting parameters and vibration parameters on the surface texture geometries are comprehensively analyzed.Finally,based on the material removal mechanism,surface generation models are established both for the cylindrical and face surfaces of a cylinder to provide theoretical support for micro/nano-structured functional surface machining.A 2D vibration-assisted cutting method is proposed for the hierarchical freeform surface fabrication,which can provide theoretical support for the fabrication of the integrated micro/nano-structured functional surfaces.In the 2D vibration-assisted cutting process,the freeform component of the surface is realized by 1D vibration,while the hierarchical micro/nano-structures are generated by 2D high frequency vibrations with small vibration amplitudes.Benefiting of the new working principle of the proposed 2D vibration-assisted cutting method,it operates in the Cartesian coordinate system,which can overcome some inherent drawbacks of the conventional fast tool servo based diamond turning in cylindrical coordinate system.Based on the working principle of the 2D vibration-assisted cutting method,the determination of the toolpath,considering tool nose radius and cutting parameters,is presented and used as the theoretical foundation for hierarchical freeform surface fabrication.A micro-image machining method is proposed to machine the micro-images on micro freeform surfaces,which overcomes the problems of poor machining quality and the difficulty in machining micro-images on metal micro freeform surface by conventional methods.Based on the vibration-assisted cutting principle,a toolpath generation algorithm is developed by considering the toolpath components from both the grayscale image and the freeform surface.The research can provide theoretical support for the application of micro-images in anti-counterfeiting field.A double frequency vibration cutting method is proposed to efficiently and flexibly fabricate the micro freeform surface on hard-to-cut materials.In the double frequency vibration cutting process,a 1D low frequency vibration is used to generate the micro freeform surface,while an ultrasonic elliptical vibration is responsible for improving the machinability of the hard-to-cut material.Based on the working principle of this double frequency vibration cutting process,a surface roughness model is built to analyze the cutting parameters on the surface roughness.Furthermore,the cutting tool selection principle in the double frequency vibration cutting process is comprehensively analyzed for optimizing the selection of the cutting tool.Finally,the toolpath generation with ultrasonic vibration compensation is conducted to generate the toolpath for the designed surface.A set of typical machining experiments were conducted to demonstrate the feasibility of the proposed methods.Firstly,the surface texturing experiments have been conducted using a 2D non-resonant vibrator.The experimental results showed that arbitrary complex surface textures can be generated in one step by summing several different sinusoidal vibration signals.Secondly,a 2D vibration-assisted cutting system was built based on the 2D non-resonant vibrator.Then,hierarchical sinusoidal and discontinuous cubic surface arrays were successfully machined,which have verified the cutting ability of the 2D vibration-assisted cutting system and the effectiveness of the toolpath generation strategy.Furthermore,the micro-images machining experiments were conducted using this 2D vibration-assisted cutting system.The experimental results have shown that the micro-images can be successfully machined both on flat and freeform surfaces,demonstrating the feasibility of the proposed method for micro-image machining.Finally,a new double frequency vibrator was designed and used for building the double frequency vibration cutting system.Then,machining experiments have been conducted on hardened steel to verify the feasibility of the proposed double frequency vibration cutting method.The experimental results showed that double frequency cutting method can significantly improve the surface quality of machined freeform surfaces.