【作者】 焦锋；

【导师】 赵波； 朱训生；

【作者基本信息】 上海交通大学 ， 机械制造及其自动化， 2008， 博士

【摘要】 工程陶瓷零件的精密超精密加工技术越来越被得到重视,不同的精整加工方法被提出和应用。固着磨料高效研磨技术是在离散磨料研磨基础上发展起来的一种精整加工技术,兼具超精密磨削和传统研磨的特点,较好解决了传统的游离磨料研磨效率低、磨料浪费严重、研磨质量不易控制等缺点,并且克服了传统超精密磨削中对环境和机床依赖性大等不足。同时考虑到超声振动加工方法在加工硬脆材料方面独特的优越性,本文提出了采用固着磨料对工程陶瓷进行超声辅助研磨这一课题,将特种加工与普通超精密加工技术相结合,高效获得工程陶瓷材料高精密超光滑加工表面。本课题在河南省杰出人才创新基金和河南省自然科学基金的资助下,选择常见的Al2O3、ZrO2工程陶瓷和目前陶瓷界研究热点之一的ZTA复相陶瓷作为研究对象,对工程陶瓷的超声辅助固着磨料高效研磨机理及其表面加工质量进行了系统的理论和试验研究。研究内容主要包括:1.针对工程陶瓷精密外圆类零件的高效精密加工要求,提出超声辅助固着磨料高效研磨技术,并研制出相应的加工装置。采用有限元方法结合振动特性试验对超声研磨装置声学系统振动特性进行分析,获得在发生器频率可调范围内的系统固有频率和振型及研具内外两条金刚石丸片路径的振动幅值分布特性,研究结果为超声辅助固着磨料高效研磨机理及相关试验的研究提供有力的保证。2.通过对圆柱面超声辅助固着磨料研磨磨粒运动特性进行分析,建立了无附加超声、附加轴向、径向和切向超声振动四种模式下的单颗磨粒运动模型。基于压痕断裂力学,结合单点金刚石超声辅助单摆刻划试验,对三种超声辅助方式下的工件材料去除机理进行研究,分析了辅助超声能够增大延性加工范围的原因。基于冲量理论和振动加工理论,对附加超声振动的磨粒受力进行分析,建立了在延性域和脆性域的材料去除率理论模型,并定性讨论了影响工程陶瓷研磨去除率的因素及规律。3.试验研究了研磨参数对材料延性去除与脆性断裂比例的影响规律及研磨过程平均研磨分力比与材料脆延去除特性之间的关系。通过对ZTA陶瓷超声辅助单点金刚石单摆刻划过程的声发射信号进行时频分析,结合划痕CCI图像,获得材料脆延去除特征频率范围。构建工程陶瓷超声辅助研磨材料脆延去除特性在线监测系统,通过小波包分析,建立了基于小波包分解频带能量的材料脆延去除特性在线监测判据。4.从表面形貌、表面粗糙度、表面分形特性、表面残余应力特性以及表面物相结构的变化等五方面,对ZrO2、Al2O3和ZTA三种工程陶瓷材料超声辅助固着磨料研磨表面质量进行研究,获得不同加工方式和参数对研磨表面质量的影响规律,研究结果表明超声振动的附加在一定程度上改善了表面加工质量。5.结合生产实践要求,基于响应曲面法(RSM)建立了工程陶瓷超声辅助研磨加工材料去除率和表面粗糙度的预测模型;综合处理高效与精密的关系,以最大材料去除率为目标变量,以表面粗糙度为约束变量,同时考虑机床和工件的实际约束条件,建立了超声研磨参数优化数学模型,应用遗传算法(GA)对超声辅助研磨参数进行了寻优并进行了工程实例验证。课题研究结果有助于揭示工程陶瓷超声辅助高效精密加工机理,完善和发展工程陶瓷固着磨料研磨加工新技术,寻求高效精密延性域研磨加工新工艺,进一步推动工程陶瓷的工程实际应用。更多还原

【Abstract】 Nowadays, there are more and more attentions on the precision and ultra-precision processing technology of engineering ceramics parts, and different finishing processing methods have been proposed and put to use. The new developed high efficiency lapping technology with solid diamond abrasive based on traditional free abrasive lapping, possessing both the advantages of ultra-precision grinding and traditional lapping, is suitable for the precision processing of engineering ceramics. For it, the weaknesses of low efficiency, serious waste of abrasive, difficulty to control the quality and so on in the traditional lapping are resolved, and the severe dependence on the environment and machine tool in the ultra-precision grinding is overcomed. Meanwhile, considering the unique advantages of the ultrasonic vibration machining in the processing of hard-brittle materials, in order to ultra-precision lap engineering ceramics parts with high efficiency, a new ultrasonic aided high efficiency lapping technology for engineering ceramics cylinder is developed in this study by combining the ultra-precision lapping technology with the USM technology.Sponsored by Henan Innovative Fund for Outstanding Scholars (No. 0421001200) and Henan Natural Science Fund (No. 0411053500), a series of theoretical and experimental studies on the ultrasonic aided high efficiency lapping mechanism and surface machining quality of Al2O3、ZrO2 and ZTA engineering ceramics are carried out in this project. The main contents of this study are as follows: 1. Ultrasonic aided high efficiency lapping technology of engineering ceramics is put forward and the corresponding machining device is researched to meet the precision machining requirements for engineering ceramics cylindrical parts. The vibration characteristics of acoustic system in the ultrasonic lapping device are clarified on the base of finite element analyses (FEA) and vibration characteristics experiments. The system natural frequencies within the adjustable scope of generator and corresponding vibration modes are analyzed, and the vibration amplitude distribution characteristics along the two paths of diamond pellet installation location in the lapping tool are obtained. The study results provide a powerful guarantee to the research of ultrasonic aided high efficiency lapping mechanism and related experiments.2. Single-grit motion models with additional axial, radial and tangential ultrasonic vibration and without additional ultrasonic vibration are established respectively through the analyses of the movement characteristics in the process of ultrasonic aided lapping of the engineering ceramics cylinder. Based on indentation fracture mechanics and ultrasonic aided pendulum scratch tests with single-point diamond, the material removal mechanisms in the three ultrasonic aided scratch modes are investigated. The reasons that ultrasonic assistance can enlarge the ductile regime are analyzed. Based on the impulse theory and the vibration machining theory, the material removal rate (MRR) models in ductile and brittle regime are established and the influencing factors and rules on MRR in ultrasonic aided lapping of engineering ceramics are discussed qualitatively.3. The effect of lapping parameters on the proportions of ductile removal and brittle fracture removal is discussed experimentally, and the relationship between the ratio of lapping component forces and material removal character is investigated. The characteristic frequency range of material removal is obtained through the time-frequency analysis of the acoustic emission signals in single point diamond pendulum scratch of ZTA engineering ceramics together with the CCI images of scratch marks. The in-process identification system of material removal mode in the process of ultrasonic aided lapping of engineering ceramics is constructed, and the in-process material removal criteria is established based on the wavelet packet frequency band energy decomposition of AE signals.4. The surface processing quality characteristics in ultrasonic aided lapping of ZrO2, Al2O3 and ZTA engineering ceramics are investigated experimentally. The influence rules of different lapping modes and parameters on the surface quality are researched from different aspects including surface topography, surface roughness, surface fractal characteristic, surface residual stress and surface phase structures, etc. The research results show that surface quality is improved to a certain extent for the assistance of ultrasonic vibration.5. The prediction models of surface roughness and material removal rate in the process of ultrasonic aided lapping are built using response surface methodology (RSM). To deal with the relationship between the high efficiency and precision synthetically, taking the maximum material removal rate as target variable and the surface roughness as bounded variable, and considering the actual constraint between the machine tool and the workpiece, the parameters optimization mathematical model is constructed, and the optimized parameters are solved by genetic algorithm (GA) and validated by the contrast experiments.The research results are help to reveal the precision and high efficient mechanism of ultrasonic aided lapping, develop the new technology of solid abrasive lapping of engineering ceramics, and further promote the applications of engineering ceramics.更多还原