臺灣博碩士論文加值系統

滑動機構為機械最常見之運動機構，也廣泛地應用在機械的進給系統，其摩擦特性影響機械運動性能甚鉅，故掌握滑動面摩擦特性為機械性能提昇的重要關鍵。滑動面的典型應用為使用於重負荷低摩擦之高精度進給系統的工具機硬軌，硬軌會加以鏟花以提昇其滑動摩擦特性，然而人工鏟花之品質因人而異，亟需以穩定的加工方法且有系統地探討滑動面之摩擦特性。本研究針對此課題以機械加工之滑動面紋理仿效鏟花表面，探討在滑動面加工不同表面紋理對於該滑動面摩擦特性的影響。
本研究首先分析產業使用之鏟花方式、幾何指標以及滑動摩擦之特性，作為設計表面紋理的依據，並設計及架設滑動摩擦力量測系統，將加工檢測後之滑塊於乾摩擦與潤滑條件下量測不同運動速度及負荷情況下之摩擦特性。研究採用單位面積之凸點數(PPI)與單位面積凸點所佔面積百分比(POP)為指標，分別設計並以機械加工製作PPI分別為0（平面）、10、20、40與50五種凸點密度，搭配接觸面積比為30%、50%與100%（平面），且深度為20μm、低點形貌為連續溝槽或是不連續的油袋凹坑，以及紋理與運動方向夾角為45°與90°之滑塊，加工之滑塊經檢測後分別在4.7kg、9.4kg、11.75kg及14.1kg之負載下量測其在400mm/min、1200 mm/min、2000 mm/min、2800 mm/min以及3600 mm/min運動速度之摩擦特性，並比較其與人工鏟花滑塊之摩擦特性。
本研究之結果歸納如下：(1) 機械加工紋理以PPI為40、POP為50%形貌為凹坑油袋的滑塊之摩擦表現最接近人工鏟花；(2) 在乾摩擦或潤滑摩擦狀況下，具加工紋理或鏟花的滑動面其摩擦係數較光滑滑動面之摩擦係數為低，顯示具紋理之滑動表面可有效改善接觸面摩擦特性；(3) 在乾摩擦狀況下，各種表面紋理之鑄鐵滑塊之摩擦係數相近，其摩擦係數隨相對運動速度增加而漸降；負荷增加時，摩擦係數略為降低，且摩擦係數隨滑塊接觸面積比增加而增加；(4) 在潤滑摩擦狀況下，各種紋理滑塊的摩擦係數皆較在乾摩擦狀況下為低，在不同負載下摩擦係數隨速度變化有相似的趨勢，且其運動摩擦特性符合Stribeck曲線所描述之行為，其動摩擦係數在低速時隨運動速度提高而降低，當達到混合潤滑後，隨著運動速度的提高，摩擦係數以接近線性方式增加；(5) 在潤滑摩擦狀況下，負載較輕的滑塊其摩擦係數隨運動速度提高而降低的效果較明顯，在比較低的速度達到混合摩擦，亦即達到Stribeck曲線的反曲點；而速度高於反曲點速度後，運動摩擦係數的上升也較負載較重的滑塊來得明顯；(6) 在潤滑摩擦狀況下，不同接觸面積比以及不同紋理角度之滑塊其摩擦係數差異甚小；但摩擦係數隨單位面積凸點增加而降低，滑塊單位面積凸點較多者其摩擦係數降低較迅速，會在比較低的速度達到Stribeck曲線的反曲點；(7) 比較不同PPI與POP對於摩擦的影響顯示，PPI為50時邊界潤滑區與PPI為20及10相比較短，進入到液動潤滑區的速度較低，POP為30%時較POP為50%的滑塊在邊界潤滑區的摩擦係數較小。
綜合上述成果，本論文之研究結果證實滑動面之表面紋理可有效降低運動摩擦，透過不同表面紋理之配置可作為「機器鏟花」加工之依據，有效改進工具機產業長期無法掌握鏟花特性之情況，並可進一步應用於其它運動接觸面以調整其摩擦特性。

Sliding mechanism is one of the most commonly used mechanisms in mechanical devices. A typical application is the guideway widely used in the feeding system for heavy-duty low-friction high-precision machine tools. The guideway is manually scrapped to reduce the friction for better positioning performance. The qualities of manual scraping however are unstable and difficult to control. As the frictional properties of sliding surface greatly affect the motion performance and precision, it is a critical issue to systematically investigate the frictional characteristics of sliding surfaces by a stable machining process. In this study, surface textures, to imitate manual scrapes, are designed and machined based on geometric indices used in manual scrape. Frictional characteristics are then measured to investigate the effect of surface texture under different sliding speed.
We first analyze methods and geometric indices of manual scrape used in industrial practice. Patterns of surface texture, which are then machined on cast iron blocks, are designed based on the contact points per inch square (PPI) and area ratio of contact points (POP). The friction forces under different loadings, speeds and lubrication conditions are then measured and analyzed for each pattern. PIP of surface texture studied in this thesis are 0 (plane contact), 10, 20, 40 and 50 with POP at 30%, 50% and 100% (plane contact). The textures are either continuous grooves or isolated pockets with depth at 20μm. The friction forces of machined blocks are then measured under loadings at 4.7kg, 9.4kg, 11.75kg and 14.1kg and sliding speeds at 400mm/min, 1200 mm/min, 2000 mm/min, 2800 mm/min and 3600 mm/min. The measured data are also used as a comparison with the friction characteristics of a manually scraped block.
The results of this research are summarized as the followings. (i) Contact surfaces with textures, compared with plane surface, showed less frictions which verified that surface texture does reduce sliding friction. (ii) Machined block with PPI 40 and POP 50% pockets performs best compared to the manual scraped block. (iii) The coefficients of friction (COF) in dry sliding are about the same for all blocks while they are reduced with sliding speed increased under lubrication. The coefficient increases with higher POP but decreases when the loading increases. (iv) The friction characteristics under lubrication follow the Stribeck curve, i.e. it COF decreases with speed at lower speed but increases with speed when sliding at higher speed. (v) The COF of blocks with lower loading changes faster than that with higher loading, i.e. its Stribeck curve has higher slope. (vi) The COF of sliding block with higher POP is less than that with lower POP under lubricated sliding, though the COFs for blocks with different PIP and sliding orientation are about the same. (vii) The COF of blocks with PPI at 50 changes faster than that with PPI at 20. The COF of blocks with POP at 30% is less than that at 50%.
The results of this research verify that surface texture does reduce the sliding friction. This is an important achievement that can be used as a foundation for design texture pattern to improve the frictional characteristics of the surface “scraped by machine”. The results can be further employed in various contact surfaces to improve it frictional characteristics.

摘要 I
Abstract III
誌謝 V
目錄 VI
圖目錄 VII
表目錄 VIII
1.1研究動機及目的 1
1.2文獻回顧 2
1.3研究方法與流程 4
第二章 鏟花與磨潤特性 6
2.1鏟花之功能 6
2.2鏟花之幾何指標 7
2.3人工鏟花 9
2.4接觸面摩潤特性 13
第三章 表面紋理設計與加工 16
3.1 表面紋理設計 16
3.2表面紋理加工 18
3.3機械加工與人工鏟花之比較 22
第四章 摩擦特性量測 25
4.1量測設備與架設 25
4.2量測數據之分析 26
4.2.1乾摩擦狀態下的摩擦行為 26
4.2.2潤滑狀態下的摩擦行為 28
4.2.3不同潤滑狀態之比較 33
第五章 結論與展望 35
參考文獻 37
附錄：量測設備與材料規格 39

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