| With the rapid development of micro/nano technology,the micro/nano processing technology has been widely used in aerospace,medical,precision engineering and robot fields.However,the widely used micro/nano processing technologies,such as lithography and high energy beam processing,have the disadvantages of complex processing technology,high processing environment requirements and high processing costs;the mechanical scratching technology based on atomic force microscope(AFM)has the advantages of low cost,high processing accuracy,low requirements of processing environment and wide range of processing materials.However,the AFM mechanical scratching technology has the problems of small processing size,low processing depth and low processing speed,which limit its application in high-tech fields.Therefore,it is of great strategic significance to build a new type of cross-scale micro/nano scratching system to improve China’s competitiveness and equipment level in the high-tech field.As one of the important devices in the field of modern micro/nano manufacturing,the piezoelectric actuator based on the inverse piezoelectric effect has the characteristics of nanometer resolution,large output and fast response.However,the existing piezoelectric actuators,such as direct driving type piezoelectric actuators,inertial type piezoelectric actuators and inchworm type actuators,are difficult to realize the characteristics of large stroke,large output force,high accuracy and multidegree of freedom at the same time.To solve the above scientific problems,this thesis will start with the design of piezoelectric actuators with different actuation principles,and propose a multi-degree-of-freedom piezoelectric precision manipulate system for cross-scale micro/nano scratching.Firstly,the overall system architecture design will be carried out to provide theoretical guidance for the designing piezoelectric actuators in the following chapters;Next,the design,prototype processing and experimental characteristics of direct driving type piezoelectric actuator and inchworm type piezoelectric motion platform are carried out respectively;Finally,according to the developed direct driving type piezoelectric actuator and inchworm type piezoelectric motion platform,a system prototype that can realize cross-scale scratching is constructed,and cross-scale micro/nano scratching experiments are carried out.The specific research content of this thesis includes the following four aspects:First of all,the conceptual design of the cross-scale micro/nano scratching system is carried out according to the actual needs,and the layout scheme of the direct driving type piezoelectric manipulator and inchworm type piezoelectric motion platform is determined.Finally,the basic architecture of the cross-scale micro/nano scratching system is determined.Based on the design and analysis of direct driving type piezoelectric manipulators,the working mode of piezoelectric components is described,the patch and sandwich excitation methods of piezoelectric manipulators are described,and the basic structure of a 3-DOF direct driving type piezoelectric manipulator is proposed.Imitate the basic motion mode of inchworm,explain the actuating principle of 2-DOF inchworm type piezoelectric motion platform,and formulate the excitation voltage signal for the action sequence of two direction driving feet in the actuating process.The design of flexure hinge element is carried out,and a theoretical fully decoupled structure scheme of flexure hinge element is proposed.Based on the structural scheme of flexure hinge elements,a basic architecture of 2-DOF inchworm type piezoelectric motion platform is proposed.Through the finite element analysis software,the optimization design of the 3-DOF piezoelectric manipulator is carried out to determine its final material parameters and structural dimensions.The kinematics model of the 3-DOF piezoelectric manipulator is established,which provides theoretical support for the trajectory planning of the piezoelectric manipulator in the open loop or semi closed loop state.The experimental prototype is developed and its motion characteristics are tested.The experimental results show that the motion range of the piezoelectric actuator is 13.4μm×13.3μm×3.1μm.The linear displacement resolution is better than5 nm.The first order resonant frequencies of X direction,Y direction and Z direction are 2.734 k Hz,2.758 k Hz and 16.462 k Hz,respectively.The hysteresis rate is less than2%.The closed loop control system of the 3-DOF piezoelectric actuator is constructed and relevant experimental tests are carried out.The positioning accuracy of ±18nm is achieved within ±6μm stroke.The experimental results show that the 3-DOF piezoelectric actuator has the advantages of compact structure,low hysteresis and high accuracy.The equivalent stiffness model of the flexure hinge element in the 2-DOF inchworm type piezoelectric motion platform is established and its structural optimization design is carried out to determine its final material parameters and structural dimensions.Based on the inchworm actuating mechanism in bionics,an inchworm type 2-DOF piezoelectric motion platform prototype is developed and the output characteristics under inchworm working mode are tested.The maximum movement stroke in X and Y directions are 40 mm,the maximum output speed are about 1mm/s,and the maximum output force is 41.5N.The experimental results show that the proposed motion platform has the characteristics of large stroke,two degrees of freedom motion,large output and good step consistency.Finally,based on the 3-DOF piezoelectric manipulator and the 2-DOF piezoelectric motion platform,a prototype of the cross-scale micro/nano scratching system is developed.Cross-scale micro/nano scratching experiments are carried out,including four representative micro/nano structures: array triangle,array circle,concentric triangle and concentric circle.Meanwhile,the micro/nano scratching experiments based on the principle of vibration assisted machining are carried out.The experimental results show that the developed cross scale micro nano lithography system not only realizes the cross-scale micro/nano structure scratching from nanometer scale to millimeter scale on plane components,also provides a new way for the cross-scale scratching of planar two-dimensional micro/nano structures,and has the ability to improve the quality of micro/nano scratching under the principle of vibration assisted machining. |
PDF Full Text Request