潤滑性能光學分析儀製作與潤滑劑油膜厚度影響研究

The Fabrication of Optical Lubrication Device and Applied Influence of Lubricants on The Film Thickness

蘇琮仁(Tsung-Jen Su)

指導教授 ： 洪政豪

國立虎尾科技大學/工程學院/機械與機電工程研究所/碩士(2013年)

https://doi.org/10.6827/NFU.2013.00054

摘要

摘要
本論文利用光干涉原理製造一個潤滑性能光學分析儀，並針對固定滑塊傾角、不同切線速度、不同負載、以及不同潤滑油性質探討不同油膜厚度的影響，並用液動潤滑理論驗證其可行性。
主系統在一定的負載下，以靜止的滑塊平面與施加切線速度的石英玻璃盤形成液動潤滑，而產生油膜厚度，並利用光干涉原理對潤滑油的最薄油膜厚度進行量測，而滑塊工作面為高反射率研磨拋光表面，石英玻璃盤表面鍍有Cr薄膜與SiO2薄膜，利用微型結構對滑塊設置，使滑塊與石英玻璃盤做液動潤滑而保持傾角固定但是可以上下運動。系統採用鹵素光源與光影像擷取器，在油膜厚度達奈米時依然可以獲得清晰的干涉圖像，目前利用本機台可以量測到約100 nm油膜厚度，最小解析度還需經過較嚴密的測試，透過伺服馬達及PLC控制石英玻璃盤的切線速度，可以獲得有規則的光強曲線圖，利用擷取的干涉圖像配合等厚干涉計算出油膜厚度。
利用上述潤滑性能光學分析儀，研究了三種不同潤滑油對液動潤滑之油膜厚度影響，包含有兩種生質潤滑油及一種普通礦物油，以相同材料的滑塊與不同潤滑油形成油膜界面，結果顯示，當負載越大時，油膜厚度呈現越薄的趨勢，傾角角度越大時油膜厚度呈現越厚的趨勢，但當傾角到達一定角度時，油膜厚度隨著傾角增大而變薄，上述的油膜厚度變化推測為產生空蝕(Cavitation)現象產生，實現量測系統的可行性。
本實驗所使用的三種潤滑油，R68潤滑油、咖啡生質潤滑油、稻稈生質潤油，在施加壓力(54 kPa)，較低轉速時12 (mm/s) 與高轉速時61 (mm/s)，稻稈生質潤滑油與R68潤滑油油膜厚度最厚，最低油膜厚度為咖啡生質潤滑油，對於R68潤滑油與稻桿生質潤滑油油膜厚度較厚原因，判斷為接觸角影響，接觸角現象越低，呈現黏附力較大，油膜厚度較厚。
在施加壓力下(408 kPa)，較低轉速時12 (mm/s) 與高轉速時61 (mm/s)，咖啡生質潤滑油油膜厚度較厚，其次為R68潤滑油和稻稈生質潤油，三種潤滑油在較重施加壓力下，油膜厚度有相同的趨勢與現象，隨著施加壓力越大接觸角影響油膜厚度的效果越不明顯，油膜厚度下降之原因為施加壓力因素影響較大。
利用奈米粒徑分析儀結果顯示，咖啡生質潤滑油奈米粒徑平均為：258 nm，與稻桿生質潤滑油奈米粒徑平均為：285 nm，R68潤滑油奈米粒徑平均為：92 nm，所以潤滑油中奈米顆粒的大小對油膜厚度差異影響不大。

關鍵字

面接觸 ； 液動潤滑 ； 傾角 ； 切線速度 ； 光干涉 ； 油膜厚度 ； 生質潤滑油 ； 奈米顆粒

並列摘要

Abstract
This study used the principle of optical interference to create an optical analyser for measuring lubricant performance. The effects thatthe fixed angle of inclination to the slider, varyingtangential speeds, different loads, and variouslubricant properties have on the lubricant film thickness wereexamined. Hydrodynamic lubrication theory was adopted to assess the feasibility of the proposed analyser.
Under a specific load, the main system generatedhydrodynamic lubricationbetween the surface of a static slider and a fused-silica (SiO2)plate, on whicha tangential speed was applied. The resulting minimum film thicknesswas then measured using the optical interference principle. The workingsurface of the sliderwas a high-reflectance polished surface. The surface of the fused-silica plate was coated with Cr and SiO2 films. A microstructure was used to installthe slider, which retained a fixed angle of inclination (although up-down movement was allowed) and underwent hydrodynamic lubrication with the fused-silica plate. The proposed system adopted halogen light sources and anoptical image extractor to capture clear interference images of the lubricant filmthickness at the nanoscale. The minimum lubricant filmthickness measurable using the proposed device was approximately 100 nm, and the minimum resolution necessitated relatively extensive examination. By employing a servo motor and programmable logic controller, the tangential speed of the fused-silica plate could be controlled, generating a regular luminous intensity curve. The lubricant film thickness was calculated using the capturedinterference images combined with equal thickness interference.
The proposed opticallubricant performance analyser was used to investigate the effectsthat three types of lubricants (two biolubricants and one mineral oil) had on the thickness of hydrodynamic lubricant film. Sliders of the same material formed alubricant film interface with the different lubricants. The results showed that when the load was increased, the lubricant film thickness decreased; the larger the angle of inclination, the thicker the lubricant film thickness. However, when the angle of inclination reached a specific degree, the lubricant film thickness declined in correlation to the angle of inclination. Such variations in film thickness may occurbecause of the cavitation phenomenon,which verifies the feasibilityof the proposed measurement system.
The three lubricants used for this experiment were R68 lubricant and biolubricants derived from coffee and rice straw. Under a pressure of 54 kPa at low (12 mm/s) and high (61 mm/s) rotational speeds, the thickness of rice straw biolubricant and R68 lubricant films was higher than that of the coffee biolubricant. The greater film thickness of R68 lubricant and rice straw biolubricant was attributed to the contact angle. The smallerthe contact angle, the higher the adhesion is, resulting in greater lubricant film thickness.
Under a pressure of 408 kPa at low (12 mm/s) and high (61 mm/s) rotational speeds, the thickness of the coffeebiolubricantfilm exceeded that of the R68 lubricant and rice straw biolubricantfilms. The three lubricants exhibited identical trends regarding lubricant filmthickness under high pressure. When the pressure was increased, the effect of the contact angle on the lubricant film thickness decreased in significance, and the reduction in film thickness was primarily attributed to high pressure.
The nanoparticle analyserresults showed that the average nanoparticle size of the coffee and rice straw biolubricants and R68 lubricant was 258 nm, 285 nm, and 92 nm, respectively. Thus, the size of the nanoparticles in lubricants has minimal influence on the thickness of lubricant film.

並列關鍵字

Angle of inclination ； biolubricant ； hydrodynamic lubrication ； nanoparticle ； lubricant film thickness ； optical interference ； surface contact ； tangential spee

參考文獻

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