本文選題：超聲拋光 + 超聲空化�。� 參考：《蘇州大學(xué)》2015年碩士論文

【摘要】：模具在現(xiàn)代工業(yè)的應(yīng)用日益廣泛,激烈的市場(chǎng)競(jìng)爭(zhēng)和對(duì)產(chǎn)品質(zhì)量要求的不斷提升致使對(duì)模具表面處理趨向精密化。拋光是模具制造業(yè)中一道至關(guān)重要的工序,拋光工序直接影響產(chǎn)品的性能。眾多材料具有一些特性,如持續(xù)高溫下的高強(qiáng)度和剛度、極高的硬度、脆性、耐腐蝕性、抗氧化性和化學(xué)惰性等,這些特性均需經(jīng)過(guò)包括拋光在內(nèi)的精密加工才能得以體現(xiàn)。目前國(guó)內(nèi)對(duì)模具的拋光,特別是異型的模腔主要依賴于手工,拋光的質(zhì)量往往取決于操作者的熟練程度,這將直接導(dǎo)致產(chǎn)品質(zhì)量的不穩(wěn)定,甚至?xí)档彤a(chǎn)品應(yīng)有的性能;此外,手工拋光還使拋光效率低下。因此,亟需一種有效的自動(dòng)化的拋光方法能夠解決復(fù)雜曲面、凹槽、盲孔等異型腔的拋光問(wèn)題,提高拋光效率,穩(wěn)定拋光質(zhì)量。本文針對(duì)新型超聲拋光方法中的一基礎(chǔ)理論問(wèn)題進(jìn)行了研究,對(duì)由超聲換能器高頻振蕩產(chǎn)生的超聲空化進(jìn)行了理論分析和數(shù)值模擬。超聲拋光的復(fù)雜性和微觀性因素,包括聲壓場(chǎng)和汽含率的分布、微觀磨粒的運(yùn)動(dòng)機(jī)理以及各影響因素對(duì)超聲空化的影響,都難以采用實(shí)驗(yàn)手段直接觀測(cè),因此,本文采用了基于CFD的數(shù)值仿真方法對(duì)上述關(guān)鍵問(wèn)題進(jìn)行了研究,主要的內(nèi)容和創(chuàng)新性成果如下:(1)文中首次采用FLUENT中的湍流模型、空化模型以及動(dòng)網(wǎng)格模型模擬了超聲拋光中的聲致空化現(xiàn)象,分析了超聲空化產(chǎn)生的能量可加強(qiáng)磨粒對(duì)模具異型腔的拋磨,導(dǎo)致更為強(qiáng)烈的材料去除,并給出了具體的驗(yàn)證方法。(2)本文還利用MINITAB中DOE模塊對(duì)拋光試驗(yàn)進(jìn)行了正交設(shè)計(jì),得到各影響因子之間的交互作用以及影響超聲拋光的最主要因素。(3)另外,研究中并未發(fā)現(xiàn)空化的選擇性,空泡在模具異型腔內(nèi)的分布相對(duì)穩(wěn)定,集中出現(xiàn)在模具異型腔底面中心附近,而在內(nèi)壁處和邊緣地帶相對(duì)較少。根據(jù)空化在模具異型腔內(nèi)的分布,磨粒的速度發(fā)生相應(yīng)的變化。(4)為使超聲拋光達(dá)到更精密的拋光效果,需抑制空化效應(yīng)對(duì)磨粒材料去除率產(chǎn)生的影響,而著重強(qiáng)化磨粒本身對(duì)工件表面的研磨作用。(5)可通過(guò)改變超聲頻率、振幅、液體黏度以及工具頭深度等改變超聲拋光過(guò)程中空化作用的強(qiáng)弱,這些參數(shù)的合理范圍值以及它們之間的交互影響可以依據(jù)DOE設(shè)計(jì)的正交試驗(yàn)而獲得。
[Abstract]:The application of mould in modern industry is more and more extensive. The fierce market competition and the continuous improvement of product quality make the surface treatment of mould become more and more precise. Polishing is one of the most important processes in die manufacturing industry, and the polishing process directly affects the performance of products. Many materials have some properties, such as high strength and stiffness, extremely high hardness, brittleness, corrosion resistance, oxidation resistance and chemical inertia. At present, the domestic polishing of mould, especially the special mold cavity, mainly depends on the handwork, and the polishing quality often depends on the operator's proficiency, which will directly lead to the instability of the product quality and even reduce the due performance of the product; in addition, Manual polishing also makes polishing inefficient. Therefore, an effective automatic polishing method is urgently needed to solve the polishing problems of complex curved surfaces, grooves, blind holes and other special-shaped cavities, to improve the polishing efficiency and to stabilize the polishing quality. In this paper, a basic theoretical problem in the new ultrasonic polishing method is studied, and the ultrasonic cavitation caused by the high frequency oscillation of the ultrasonic transducer is analyzed theoretically and numerically simulated. The complexity and microcosmic factors of ultrasonic polishing, including the distribution of sound pressure field and vapor holdup, the motion mechanism of micro-abrasive particles and the influence of various factors on ultrasonic cavitation, are difficult to be observed directly by experimental means. In this paper, the numerical simulation method based on CFD is used to study the key problems mentioned above. The main contents and innovative results are as follows: (1) the turbulence model in FLUENT is used for the first time. The cavitation model and dynamic mesh model are used to simulate the acoustic cavitation phenomenon in ultrasonic polishing. The energy generated by ultrasonic cavitation can enhance the grinding of the mold cavity and lead to stronger material removal. This paper also uses DOE module in MINITAB to carry on the orthogonal design to the polishing experiment, and obtains the interaction between the influencing factors and the most important factor of the ultrasonic polishing. The cavitation selectivity was not found in the study. The distribution of cavitation was relatively stable in the special cavity of the mould, which concentrated near the center of the bottom surface of the die shaped cavity, but relatively few in the inner wall and the edge zone. According to the distribution of cavitation in the die cavity, the velocity of abrasive particles changes correspondingly. In order to achieve more precise polishing effect, the effect of cavitation effect on the removal rate of abrasive material should be restrained. The grinding effect of abrasive particles on the workpiece surface can be enhanced by changing the ultrasonic frequency, amplitude, liquid viscosity and the depth of the tool head. The reasonable range of these parameters and their interaction can be obtained according to the orthogonal test designed by DOE.
【學(xué)位授予單位】：蘇州大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TG76

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