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|Title:||Diamond milling servo based mechanical machining system for micro/nanomanufacturing|
|Advisors:||To, Sandy (ISE)|
|Keywords:||Microstructure -- Surfaces.|
Nanostructures -- Surfaces.
|Publisher:||The Hong Kong Polytechnic University|
|Abstract:||Currently, how to massively generate the bio-inspired micro/nanostructures with high efficiency and flexibility is a prohibitive issue for both mechanical and non-mechanical manufacturing systems. In the present study, a novel diamond milling servo (DMS) system is proposed and investigated both theoretically and experimentally for micro/nanomanufacturing. In the DMS system, the techniques of raster milling and fast tool servo (FTS) or slow tool servo (STS) are combined to overcome some inherent limitations in the two most common diamond cutting systems, accordingly enhancing the corresponding machining capabilities for mechanical micro/nanomanufacturing. On the basis of the fundamental frame of the DMS system, the concepts of bi-axial servo based DMS system with addition of another translational servo motion along the side-feeding direction, intersecting DMS system by adopting multiple cutting directions for one surface, and rotary vibration assisted DMS (RV-DMS) system are further developed to extend the flexibility and efficiency of the DMS system. Basic working principle, optimal toolpath determination, estimation of surface generation, and development of the corresponding mechatronic systems are comprehensively investigated to provide solid basis for practically implementing these innovative DMS based techniques for micro/nanomanufacturing operations. The unique features of the proposed DMS based micro/nanomanufacturing system can be summarized as follows: (I). With the DMS system, by exchanging the positions of the diamond tool and the workpiece, the machining operation is essentially transferred from the cylindrical coordinate system of the FTS/STS to the Cartesian coordinate system. The superimposition of the transitional servo motion on the workpiece provides the capability for the generation of ultra-fine surfaces with complicated shapes. On the other hand, rotation of the diamond tool allows the DMS system to operate with constant cutting velocity, making the DMS system be free from the inherent limitations (i.e. cutting quality inconsistence, azimuth sampling conflicts and tracking bandwidth limitation) in FTS/STS based diamond turning of micro-structured functional surfaces.|
(II) By actively controlling the residual tool marks to be functional nanostructures, various kinds of hierarchical micro-nanostructures featuring a superposition of secondary nanostructures on the primary micro-structured surfaces can be sufficiently generated by means of the DMS based micro/nanomanufacturing system. Feature sizes of the second order nanostructures can be well tuned by deliberately controlling the intersections of the tool loci through the intersecting DMS system as well as controlling the side-feeding motions through the bi-axial servo based DMS system. Compared with FTS/STS based diamond turning, the intersecting and bi-axial servo based DMS systems make the generation of the second order nanostructures free from the dependence on working bandwidth of the mechatronic systems. Instead, the dependence is shifted to the geometry and side-feeding motion of the diamond tool. It is of high significance for large-scale generation of high order nanostructures with only limited bandwidth of the servo motion of the machine tool. (III) By synthesizing the rotary vibration and the basic DMS system, the RV-DMS system is further proposed and systematically investigated. In the RV-DMS system, the diamond tool is actuated along the three translational directions and concurrently rotates with the spindle. Since the rotary vibration system is working with high frequency and high motion resolution, the RV-DMS system is essentially a multi-scale mechanical machining system in both time and spatial domains. Compared with other machining systems, the inherent hierarchical cutting architecture allows the RSV-DMS system to be more suitable for the generation of the bio-inspired hierarchical micro/nanostructures. (IV) In the RV-DMS system, the rotary vibration and the DMS systems are independently responsible for the generation of the secondary nanostructures and the primary complex surfaces, respectively. Meanwhile, active control of both material removal and tool mark residual is employed in the RV-DMS system to construct the complicated micro/nanostructures. Moreover, rotary vibrations of the diamond tool at a constant rotational distance offer an inherent constant cutting velocity, leading to the ability to generate homogeneous micro/nanostructures with fixed amplitudes and frequencies of the vibrations, even over large-scale surfaces. Furthermore, by deliberately combining the non-resonant three-axial vibrations and the servo motion, the generation of a variety of micro/nanostructures with complex shapes and with flexibly tunable feature sizes can be achieved. Deriving from these uniquenesses of the proposed micro/nanomanufacutring sytem, the main contributions of the thesis include: (i) Provide an efficient and powerful DMS based micro/nanomanufacturing system for large-scale generation of the micro-structured functional surfaces as well as the bio-inspired hierarchical micro/nano structures; (ii) Provide the thorough and systematic guidance for advanced design and implementation of the compliant mechanism based mechatronic system with multiple degree-of-freedoms for micro/nanomanufacturing; (iii) Provide solid theoretical basis for optimal toolpath determination and structured surface estimation for the DMS based micro/nanomanufacturing system.
|Description:||PolyU Library Call No.: [THS] LG51 .H577P ISE 2016 Zhu|
xxvi, 208 pages :color illustrations
|Rights:||All rights reserved.|
|Appears in Collections:||Thesis|
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Checked on Sep 18, 2017
Checked on Sep 18, 2017
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