随着对减小零件尺寸和增加其复杂性和准确性的日益增加的需求，传统机床已经不能有效的加工微型元件了。一个典型的例子是牙科种植体（生物医学设备）和和用于机械手表机芯的齿轮轴。由于这些零件的复杂几何形状和严格的公差要求，市面上只有很少一部分机床有能力加工它们。我们设计的多轴数控“车削-铣削-滚齿加工中心对加工精密复杂工程零件是非常有效的。此机器为8轴机床，除了执行加工的8轴外，还有一个自动上料机构和一个自动收集机构,可以实现自动上料，加工，收集等整条生产线的运作。运用电子齿轮技术以保证精密滚齿功能；运用先进控制技术（深层交叉耦合技术）以保证多轴的同步控制，实现加工的高效，高精度，并且容易使用。另外，为了保障机床精度，我们研发了多轴数控机床几何误差的软件补偿技术。根据实验测试，此加工中心的车削精度为0.003毫米，铣削精度为0.005毫米，滚齿误差小于0.0075毫米。 / 众多的生物医学零件是轴不对称零件。虽然这些零件可以用传统的数控加工方法进行加工，但是效率极低且成本高。而基于我们加工中心的新型铣削方法可以有效、高精度的加工这些零件。这种方法是运用极坐标的插值原理，比利用笛卡尔直角坐标系加工的原理更加优越，特别是当需要一个线性轴和旋转轴插值生成曲线时。为了方便使用这个极坐标插值模块，我们开发了一系列特殊的极坐标加工G代码。整个开发的程序模块最终融入我们多轴数控“车削-铣削-滚齿“加工中心。 / 另外一个重要的发现是运用滚齿方法加工轴对称和轴不对称零件。从滚齿方法被发明出来的这100年中，其一直是最有效的加工齿轮的方式。它的高效是由于多个刀齿同时切削工件。现在，滚齿是一种标准的加工方式并且每天运用这种方法加工几百万个零件。但是，没有人用这种方法加工轴不对称零件。经过仔细研究滚齿原来，可以得出以下观点：一）齿轮的齿形是与滚刀的齿形一样的；二）齿轮轮廓是由工件和滚刀的相对位置确定的。把滚刀设计和控制工件和滚刀的相对位置结合起来，我们发现运用滚齿的方法是可以加工各种轴对称和非对称部分，例如：星形零件和多边形零件。特别是，该方法可以有效的加工不断变化的轴不对称零件。最后，我们比较其的加工效率和传统的铣削加工，结果验证运用这种方法的加工时间远小于采用铣削方法。 / 我们设计的加工中心和新型加工方法在生物医学工程有很多的应有。牙科种植体就是一个典型的例子。具权威机构统计，约有10%的人会在一生中选用种植牙技术对牙齿进行修复。但是不幸的是，没有人研究个性化种植体。目前，市面上的种植体并不能精确的适合病人牙根情况，完成特殊口腔环境的牙齿修复。所以，对个性化种植体的研究是迫切并具有市场效益的。关于个性化种植体研制的一个难点是其的制造。个性化种植体之所以难加工是由于它的复杂形状及所用材料（钛）。但是，我们设计的多轴数控“车削-铣削-滚齿“加工中心和基于此机床的新型加工方法可以有效、高精度的加工此种植体。 / With the ever increasing demand for reduced size and increased complexity and accuracy, traditional machine tools have become ineffective for machining miniature components. A typical example is the dental implant and the other is the pinion used mechanical watch movement. With complex geometry and tight tolerance, few machine tools are capable of making these parts. We designed and built a CNC Turn-Mill-Hob Machining Center that is capable of machining various complex miniature parts. The machining center has 8 axes, an automatic bar feeder, an automatic part collection tray, and a custom-made CNC controller. In particularly, the CNC controller gives not only higher accuracy but also ease of use. In addition, to improve the accuracy, a software based volumetric error compensation system is implemented. Based on the experiment testing, the machining error is ± 4 μm for turning, ± 7 μm for milling, and the maximum profile error is less than ± 7.5 μm for gear hobbing. / Many biomedical parts are axial asymmetric parts. While these parts can be machined using conventional CNC machining methods, the efficiency is low and the cost is high. We proposed a new CNC machining method based on polar coordinate interpolation, which is better than the Cartesian coordinate interpolation when rotational axes are involved. To facilitate the use the polar coordinate interpolation module, a special G code is developed. This module is integrated into our CNC Turn-Mill-Hob Machining Center. / Another important development is the use of hobbing method for machining axial symmetric / asymmetric parts. Invented some 100 years ago, hobbing is the most efficient method for machining gears. Its efficiency lies on multiple teeth simultaneous cutting. Presently, gear hobbing is a standard manufacturing process making millions of gears every day. Though, no one has used it for machining axial asymmetrical parts. After carefully examining the gear hobbing, it is found that the profile of the gear tooth is determined by a combination of the profile of the hob tooth and the relative position and motion between the hob and the workpiece. Therefore, by tuning the hob tooth profile and controlling the relative position and motion between the hob and the workpiece, it is possible to machine various axial symmetrical and asymmetrical parts, such as a start, a hexagon and etc. This method is efficient to machine continuously changed axial asymmetrical parts. This is validated by means of experiments. The experiments also indicate that the new method is much more efficient than the conventional milling method. / Our machining center and new machining methods have many practical applications. Dental implant is a typical example. It is estimated that 10% of the people will need dental implants in their life time. Presently, there are a number of brands in the market, though these implants may not fit for patients who have special oral conditions. In this case, custom-made implants are necessary. The key problem of the custom-made dental implant is manufacturing. Our multi-axes CNC Turn-Mill-Hob Machining Center and the new machining method can effectively machine the custom-made dental implants. Moreover, the efficient is good. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Chen, Xianshuai. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 116-127). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese. / Abstract --- p.I / 摘要 --- p.III / Acknowledgement --- p.V / Table of Contents --- p.VI / List of Tables --- p.VIII / List of Figures --- p.IX / Acronym --- p.XIII / Chapter Chapter 1: --- Introduction --- p.1 / Chapter 1.1 --- Background --- p.1 / Chapter 1.2 --- Overall Literature Review --- p.3 / Chapter 1.3 --- Objectives --- p.17 / Chapter Chapter 2: --- The Multi-Axes CNC Turn-Mill-Hob Machining Center --- p.18 / Chapter 2.1 --- A Brief Review --- p.18 / Chapter 2.2 --- The Design and Prototype --- p.20 / Chapter 2.3 --- The CNC Controller --- p.26 / Chapter 2.4 --- The Calibration --- p.32 / Chapter 2.5 --- Cutting Tests --- p.35 / Chapter 2.6 --- Summary --- p.43 / Chapter Chapter 3: --- Hobbing Gears and Axial Asymmetric Parts --- p.45 / Chapter 3.1 --- A Brief Review --- p.45 / Chapter 3.2 --- The Theory --- p.47 / Chapter 3.3 --- Computer Simulation --- p.54 / Chapter 3.4 --- Cutting Tests --- p.68 / Chapter 3.5 --- Summary --- p.78 / Chapter Chapter 4: --- Millining Axial Asymmetric Parts --- p.80 / Chapter 4.1 --- A Brief Review --- p.80 / Chapter 4.2 --- The Theory --- p.81 / Chapter 4.3 --- Cutting Tests --- p.89 / Chapter 4.4 --- Summary --- p.94 / Chapter Chapter 5: --- Machining Dental Implants --- p.95 / Chapter 5.1 --- A Brief Review --- p.95 / Chapter 5.2 --- The Database of Custom-made Dental Implant --- p.98 / Chapter 5.3 --- The Design and FEA --- p.103 / Chapter 5.4 --- Cutting Tests --- p.108 / Chapter 5.5 --- Summary --- p.110 / Chapter Chapter 6: --- Concluding Remarks and Future Work --- p.111 / Chapter 6.1 --- Concluding Remarks --- p.111 / Chapter 6.2 --- Future Work --- p.113 / Bibliography --- p.116 / Publication Record --- p.127

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The geometric dimensioning and tolerancing concept of coaxiality is often required by design engineers for balance of rotating parts and precision mating parts. In current practice, it is difficult for manufacturers to measure coaxiality quickly and inexpensively. This study examines feasibility of a manually-operated, mechanical device combined with formulae to indicate coaxiality of a test specimen. The author designs, fabricates, and tests the system for measuring coaxiality of holes machined in a steel test piece. Gage Repeatability and Reproducibility (gage R&R) and univariate analysis of variance is performed in accordance with Measurement System Analysis published by AIAG. Results indicate significant design flaws exist in the current configuration of the device; observed values vary greatly with operator technique. Suggestions for device improvements conclude the research.