臺灣博碩士論文加值系統

摘要
液靜壓軸承的負載能力以及穩定性主要受到節流器的影響。傳統毛細管或孔口式的節流器只能提供固定阻抗，並不能在軸承負荷增加時，釋出較高的流量以穩定軸承的浮動高度(油膜厚度)。因此本論文以聚氨酯 (PU) 高分子材料來製作毛細管節流器。當軸承負荷改變時，流體的壓力變化會傳遞回節流器，毛細管因此而改變形狀尺寸，造成不同的阻抗以達到補償的效果。
實驗分為靜態與動態，並以可忽略變形的鋁合金製作相同結構的節流器，作為實驗的對照標準。靜態實驗測量節流器供應壓力、輸出壓力、流量、油膜厚度；動態實驗則給予步階力(方波)的負荷變動，負荷在低值與高值間以指定的頻率異動，測量以上所提之各項數據。
靜態實驗結果顯示：(1) 與鋁節流器相比，聚氨酯節流器的阻抗較不受油溫所影響； (2) 毛細管道的高彈性變形會形成出口減縮的噴嘴，至少使流量下降至鋁合金節流的一半以下，在低負荷區甚至可相差達十倍。聚氨酯的硬度越低，則流量和油膜厚度越低；(3) 聚氨酯的硬度下降時，在較低的負荷下便已開始產生明顯的流量補償，使軸承得到較佳之剛性；但較硬之聚氨酯則適合用於高供應油壓及高負荷區；(4) 增加供應油壓，會使得最大補償流量的發生點朝高負荷區移動；(5) 選擇適當的聚氨酯硬度和供應油壓，可在特定的負荷區域得到極高甚至無限大的靜態剛性。
動態實驗結果顯示聚氨酯節流器表現良好，然須注意下列情況：(1)高供油壓力下，較軟的聚氨酯其毛細管偶爾會因強力膠脫落而導至阻塞。且因流道變形過於劇烈，所得到的實驗數據非常不穩定；(2) 在流量補償的範圍內，補償流量越大則毛細管擴孔越趨於極限，油膜厚度達到穩定的時間也就越長；(3) 若負荷方波的高值超出聚氨酯的補償範圍，負荷變動時將有流量過分補償的突點出現，但油膜厚度的突點較不明顯。

Abstract
The load carrying capacity and stability of hydrostatic bearings are mainly influenced by restrictors. Traditional capillary tube or orifice restrictors can only provide fixed impedance and are unable to stabilize the flying height of bearings (oil film thickness) by releasing higher flows when loads on bearings increase. Therefore, this paper concerns the creation of a capillary tube restrictor using polyurethane (PU), a polymer material. When the load on the bearing changes, information on fluid pressure variation is sent back to the restrictor and the capillary tube will change its shape and size accordingly to generate different levels of impedance for compensation.
The experimentation was divided into the static and dynamic parts and another restrictor in the same structure was created using an aluminum alloy with negligible deformation as the control in the experimentation. The static experiment measured the supply pressure, output pressure, flow rates and oil film thickness in the two restrictors; whereas, the dynamic experiment measured load transactions between low and high levels at a fixed frequency by providing load variation by the step function (square wave). Measurement was thus carried out to obtain data of the aforementioned items.
The results of the static experiment showed the following. (1) Compared to the aluminum alloy restrictor, the impedance in the PU restrictor was less affected by the oil temperature. (2) The high elastic deformation of the capillary tube channel led to the formation of a nozzle with a reduced outlet and therefore the PU restrictor could reduce the flow to less than half of the flow achieved by the aluminum alloy restrictor and the difference between the two could be up to 10 times in the low-load region. When the PU hardness was lower, the flow and the oil film thickness were also lower. (3) When the PU hardness dropped and the load was lower, marked flow compensation began to occur, thus giving the bearing better stiffness. On the contrary, harder PU was more appropriate for the region with high oil supply pressure and high load. (4) Increase in the oil supply pressure caused the occurrence point of maximum compensated flow to move toward the high-load region. (5) The selection of appropriate PU hardness and oil supply pressure could enable extremely high or even infinitely high static stiffness in a specific load region.
The results of the dynamic experiment showed the PU restrictor performed well, but also indicated the following noteworthy instances. (1) Under high oil supply pressure, the capillary tube in the PU restrictor could become blocked by potential superglue fall-off. Moreover, overly severe deformation of the flow channel could make the obtained experimental data highly unstable. (2) Within the range of flow compensation, higher compensated flow could stretch outlet expansion in the capillary tube to its limit and hence lengthen the time for the oil film thickness to stabilize. (3) When the high level of the loading square wave exceeded the compensation range of the PU restrictor and as soon as the load changed, the salient point of overly flow compensation would appear, whereas the salient point of the oil film thickness was less noticeable.

目錄
摘要 i
目錄 vii
圖目錄 x
表目錄 xv
第一章 緒論 1
1-1前言 1
1-2文獻回顧 2
1-2-1關於國外對於固定式節流器之研究 2
1-2-2關於國外對於補償式節流器之研究 3
1-2-3關於國內對於節流器之研究 4
1-3研究動機與方法 8
第二章 液靜壓軸成特性介紹 10
2-1液靜壓軸承原理 10
2-2流體軸承原理區分 10
2-2液壓軸承供油系統分類 12
2-3節流器種類與特性 15
2-3-1伯努利定理 15
2-3-2連續法則 16
2-3-3油的黏度 17
2-3-4 節流器之重要性 20
2-3-5固定式非補償節流器 21
2-3-2壓力補償式節流器 25
第三章 聚氨酯毛細管節流器幾何設計與架構 30
3-1毛細管材質選用之液靜壓軸承設計. 30
3-2 單孔毛細管幾何設計與架構 32
3-3 雙孔毛細管幾何設計與架構 40
3-4 鋁雙孔毛細管幾何設計與架構 41
3-5 PU雙孔毛細管幾何設計與架構 46
3-6 PU毛細孔節流器快速模具灌注法 50
第四章 實驗設備 57
4-1液靜壓軸承實驗台架構 57
4-2液靜壓機台迴路 60
4-3感測設備介紹 65
4-4 LabVIEW圖控程式軟體 71
第五章 PU雙毛細管節流器靜態實驗分析 76
5-1 PU節流器在靜壓下油溫對毛細管節流器特性實驗分析結果 77
5-2 Shore A硬度在靜壓下之個別PU節流器特性實驗分析結果 80
5-2-1鋁節流器於各壓力下之特性圖 82
5-2-2市售聚氨酯PU(M)(Shore A90)節流器於各壓力下之特性圖 83
5-2-3灌注型聚安酯PU(Shore A90)流器於各壓力下之特性圖 85
5-2-3灌注型聚安酯PU(Shore A80)流器於各壓力下之特性圖 87
5-2-3灌注型聚安酯PU(Shore A70)流器於各壓力下之特性圖 88
5-3 相同供油壓力下之各材質特性實驗分析結果 89
5-3-1於各節流器於20bar供油壓力之負載與流量關係 90
5-3-2於各節流器於30bar供油壓力之負載與流量關係 92
5-3-3於各節流器於40bar供油壓力之負載與流量關係 94
5-3-4於各節流器於50bar供油壓力之負載與流量關係 96
第六章 PU雙毛細管節流器動態實驗分析 100
6-1 於20bar供油壓力下毛細管動態性質 100
6-2 於30bar供油壓力下毛細管動態性質 103
6-3 於40bar供油壓力下毛細管動態性質 107
6-4 於50bar供油壓力下毛細管動態性質 112
第七章結論與建議 117
7-1結論 117
7-2建議 118
參考文獻 117

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