【作者】 李曙生；

【导师】 徐九华；

【作者基本信息】 南京航空航天大学 ， 机械制造及其自动化， 2008， 博士

【摘要】 工程陶瓷材料目前在航空航天、汽车及切削刀具等领域的应用日益广泛,且需求正逐年增加。金刚石砂轮性能及相关的磨削工艺参数对陶瓷工件的加工成本、效率和磨削表面完整性有决定性的影响,因此研制性能优异的新型金刚石砂轮并对其磨削性能进行科学评价,将有助于推动工程陶瓷材料的优质和高效加工。凭藉单层钎焊工具钎料层对磨料的超强把持作用和有序排布技术,本课题研制了磨粒有序排布的新型单层钎焊金刚石砂轮,并将其应用于工程陶瓷的高性能磨削,以期进一步拓宽钎焊工具的应用领域。本文完成的主要研究工作包括:(1)为实现工程陶瓷的精密磨削,根据钎焊工艺要求设计了新型结构磨粒有序排布的单层钎焊金刚石镶块砂轮。确定了合适的钎焊工艺和砂轮结构件制造工艺,重点对其回转精度进行了控制,并对磨粒的等高性进行了有效控制,成功研制出应用于工程陶瓷磨削的磨粒有序排布的细粒度新型单层钎焊金刚石砂轮。(2)阐明了单层钎焊金刚石砂轮磨削工程陶瓷的工艺基础条件,探讨了陶瓷材料脆-延性转变机理和临界条件,并对氧化锆(Y-PSZ)陶瓷的延性域去除进行了基础试验研究,进行了钎焊金刚石砂轮延性域磨削陶瓷的可行性分析。针对普通精密磨床和和高速磨床试验条件,基于脆延性转变机理对延性域磨削参数进行了科学调控。(3)通过磨削试验和磨损试验对新型单层钎焊金刚石砂轮的磨削加工性能进行了探讨,重点对氧化铝(99%)和氧化锆(Y-PSZ)两种工程陶瓷的磨削力和磨削比能进行了研究。基于单颗磨粒磨削力及力比两方面分析了钎焊金刚石砂轮的锋利度,详细分析了工程陶瓷磨削能量的耗散机制,论证了工程陶瓷磨削过程中材料去除方式存在脆-延性转变的规律。此外,进行了新型单层钎焊金刚石砂轮磨损试验研究,阐明了磨损的主要形式。(4)应用研制的单层新型钎焊金刚石砂轮进行了两种陶瓷材料的不同磨削参数下表面完整性研究,从工程陶瓷磨削后表面粗糙度、残余应力、抗弯强度以及表面/亚表面损伤等四个方面阐明了不同单颗磨粒最大切厚下的表面完整性更多还原

【Abstract】 Engineering ceramics are now widely used under great and complex demands to produce different parts in many fields such as aviation and aerospace industry, automotive industry, cutting tools manufacturing industry, etc. Because the diamond grinding wheel performance and the related grinding process parameters significantly influence the cost, efficiency and surface integrity, it is helpful to develope the innovative diamond grinding wheel and scientifically to evaluate the performance of grinding wheel for promoting ceramics machining with good quality and high productivity.Depending on the strong joining effects induced by the chemical and metallurgical behavior among the abrasive grains, the filler alloy and the metal substrate and the orderly distributed grains technology, the innovative monolayer brazed diamond grinding wheels with orderly distributed grains are developed. Subsequently the special tools were evaluated in the high performance grinding of engineering ceramics in order to further broaden the application field of the brazing diamond grinding wheels.The main contents in this paper are as follows:1) The innovative monolayer brazed diamond segmented grinding wheels with orderly distributed grains is designed according to the requirements of brazing technique to realize the precision grinding of engineering ceramics. Moreover, on the basis of determined the suitable brazing process, the machining process of the grinding wheel with structural components mainly controlling the rotary accuracy of the wheel and the equal height characteristics of grains is effectively controlled, this kind of fine-grained diamond grinding wheel applied to engineering ceramics is successfully developed.2) The technique foundation conditions of grinding engineering ceramics by the monolayer brazed diamond are elucidated and the mechanism and the critical conditions of brittle–ductile transition are investigated. What’s more, the fundamental experimental researches of the ductile mode cutting of zirconia ceramic are conducted and the feasibility of ductile grinding engineering ceramics with the brazed diamond tools is presented. Furthermore, ductile grinding parameters are scientifically optimized based on the mechanism of brittle–ductile transition according to the ordinary precision grinding machine and the high speed grinding machine.3) Grinding performance of the innovative monolayer brazed grinding wheel was investigated based on the grinding and wear experiments. The grinding force and the specific grinding energy of the alumina ceramic and the zirconia ceramic are mainly discussed. The sharpness of the brazed diamond grinding wheel is analyzed based on both the single grain grinding force and the grinding force ratio. The energy dissipation mechanism of the engineering ceramics is elucidated and the brittle–ductile transition exists in the material removal modes when grinding engineering ceramics. Furthermore, the wear experiments for the innovative monolayer brazed grinding wheel are conducted and the wear main form of the grinding wheel is investigated.4) Research on the grinding surface integrity of the two different ceramics is conducted with the fabricated innovative monolayer brazed diamond grinding wheel. The variation law of the surface integrity of engineering ceramics after being ground under the different maximum undeformed chip thickness is discussed from four aspects: surface roughness, residual stress, flexural strength and surface/subsurface damage. Furthermore, the surface integrity in the ductile grinding process is mainly investigated.更多还原