本文選題：單顆金剛石磨粒 + 機(jī)械磨損��； 參考：《華僑大學(xué)》2016年博士論文

【摘要】：金剛石磨粒工具被廣泛應(yīng)用于多種材料的高效精密加工。金剛石磨粒的機(jī)械磨損對工具壽命及加工質(zhì)量都有著重要的影響。對工具中金剛石磨粒的觀察發(fā)現(xiàn)磨粒磨損具有較大隨機(jī)性。雖然學(xué)者們試圖利用磨粒排布的思路來提高金剛石磨損的均勻性,但是其效果有限,其根本原因是金剛石磨粒的磨損機(jī)理尚不明確。本文選用立方八面體金剛石磨粒,分別制備了點(diǎn)、線、面三種與工件不同接觸形式的單顆釬焊金剛石試樣;并結(jié)合晶體結(jié)構(gòu)規(guī)劃劃擦方向,設(shè)計(jì)了九種不同的劃擦方式。跟蹤了不同劃擦方式下金剛石磨粒劃擦典型脆性材料(藍(lán)寶石)和塑性材料(Ta12W)時(shí)的材料去除體積、劃擦力、磨粒磨損體積及磨損形貌。比較分析了接觸形式、工件材料及劃擦方向?qū)饎偸チC(jī)械磨損的影響規(guī)律。采用光滑粒子流體動(dòng)力學(xué)(SPH)方法和理論計(jì)算推導(dǎo)建立了金剛石磨粒劃擦應(yīng)力理論模型,分析不同劃擦方式對金剛石磨粒劃擦過程的影響及應(yīng)力變化特征,最終建立起了金剛石磨粒的磨損理論模型,較好解釋了金剛石磨粒的磨損規(guī)律。通過上述分析和討論,本文的主要研究成果工作可概述如下:(1)影響金剛石磨粒機(jī)械磨損的主要原因是接觸形式、工件材料類型和劃擦方向。其中接觸形式的影響最為顯著,面接觸時(shí)金剛石磨粒的耐磨性明顯超過點(diǎn)、線接觸形式下的金剛石耐磨性,其中{100}晶面接觸形式的耐磨性最高。點(diǎn)、線接觸情況下,其接觸面積小而導(dǎo)致接觸應(yīng)力增大是使其耐磨性變差的主要原因。(2)金剛石磨粒機(jī)械磨損形式主要包括:裂紋,臺階狀斷裂,河流狀解理以及片狀解理。金剛石磨粒的片狀解理多發(fā)生在{111}晶面,而臺階面沿{111}晶面產(chǎn)生斷裂破碎,裂紋多沿110晶向產(chǎn)生。劃擦藍(lán)寶石時(shí),這四種機(jī)械磨損形式都存在,但劃擦Ta12W時(shí),以河流狀解理和片狀解理為主。(3)工件材料類型對金剛石的磨損形式有著顯著的影響,劃擦藍(lán)寶石(脆性材料)時(shí)金剛石磨粒主要受到擠壓應(yīng)力的作用而產(chǎn)生沿一定角度的破碎;劃擦Ta12W(塑性材料)時(shí),金剛石磨粒受到剪切力矩和擠壓應(yīng)力的綜合作用而形成平整的剪切面。(4)建立了金剛石磨粒劃擦機(jī)械磨損理論模型,分析不同接觸形式下的應(yīng)力特征模型,較好地解釋了金剛石的磨損規(guī)律;利用PBC模型,可較好解釋金剛石磨損形貌的產(chǎn)生原因。本文的研究成果豐富了金剛石磨粒機(jī)械磨損的理論研究,對優(yōu)化金剛石磨粒工具性能、制備新型金剛石磨粒工具具有實(shí)際指導(dǎo)意義。
[Abstract]:Diamond abrasive tools are widely used in high-efficiency precision machining of many kinds of materials. The mechanical wear of diamond abrasive particles has an important effect on tool life and machining quality. It is found that the abrasive wear of diamond particles in the tool is random. Although scholars try to improve the uniformity of diamond wear by using the idea of abrasive particle arrangement, its effect is limited, and the basic reason is that the wear mechanism of diamond abrasive particles is not clear. In this paper, cubic octahedron diamond abrasive particles are used to prepare single brazed diamond samples with different contact forms of points, lines and surfaces with workpiece, and nine different scratching methods are designed in combination with the crystal structure planning scratching direction. The material removal volume, scratch force, abrasive wear volume and wear morphology of typical brittle material (sapphire) and plastic material (Ta12W) were tracked under different scratching methods. The effects of contact form, workpiece material and scratch direction on the wear of diamond abrasive are compared and analyzed. The theoretical model of diamond abrasive scratch stress is established by using smooth particle hydrodynamics (SPH) method and theoretical calculation. The influence of different scratching methods on diamond particle scratch process and the characteristics of stress variation are analyzed. Finally, the wear theory model of diamond abrasive particles is established, and the wear law of diamond abrasive particles is well explained. Through the above analysis and discussion, the main research results of this paper can be summarized as follows: (1) the main reasons that affect the mechanical wear of diamond abrasive particles are the contact form, the material type of the workpiece and the scratching direction. The effect of contact form is the most obvious, and the wear resistance of diamond particles is obviously higher than that of point, and the wear resistance of diamond in line contact form is the highest, among which the {100} crystal surface contact form is the highest. When the contact area is small, the increase of contact stress is the main cause of poor wear resistance.) the mechanical wear forms of diamond grain mainly include: crack, step fracture, fluvial cleavage and flake cleavage. The lamellar cleavage of diamond grains occurs in the {111} crystal plane, while the step surface breaks along the {111} crystal plane and the crack occurs along the 110 crystal direction. These four kinds of mechanical wear forms exist when scratching sapphire, but when scratching Ta12W, the material type of workpiece mainly composed of fluvial cleavage and flake cleavage has significant influence on the wear form of diamond. When scrubbing sapphire (brittle material), diamond abrasive particles are mainly crushed at a certain angle due to the effect of extrusion stress, and when scratching Ta12W (plastic material), The diamond abrasive particles formed a flat shear surface by the combined action of shearing moment and extrusion stress. (4) the theoretical model of diamond abrasive friction mechanical wear was established, and the stress characteristic model under different contact forms was analyzed. The wear law of diamond is well explained, and the cause of diamond wear morphology can be explained by using PBC model. The research results in this paper enrich the theoretical study of diamond abrasive wear, and have practical guiding significance for optimizing the performance of diamond abrasive tools and preparing new diamond abrasive tools.
【學(xué)位授予單位】：華僑大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2016
【分類號】：TG74

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