【正文】 at can freely move in the axial direction . An arm that presses against a load cell and thereby permits friction torque measurements prevents the free rotation of this housing. Axial loading is provided by means of dead weights on a lever and is measured with a second load cell. A proximity probe that is attached to the lower holder of the stator allows online measurements of the clearance change between rotor and stator as the hydrodynamic e?ects cause axial movement of the housing to which the stator holder is ?xed. Tap water is supplied by gravity from a large tank to the center of the bearing and the leakage from the bearing is collected and recirculated. A thermocouple adjacent to the outer diameter of the bearing allows monitoring of the water temperature as the water exit the bearing. A PC is used to collect and process data online. Hence,the instantaneous clearance, friction coe?cient, bearing speed and exit water temperature can be monitored constantly. The test protocol includes identifying a reference ―zero‖ point for the clearance measurements by ?rst loading and then unloading a stationary bearing over the full load range. Then the lowest axial load is applied, the water supply valve is opened and the motor turned on. Axial loading is increased by steps of 40 N and each load step is maintained for 5 min following the stabilization of the friction coe?cient at a steadystate value. The bearing speed and water temperature are monitored throughout the test for any irregularities. The test ends when a maximum axial load of 460 N is reached or if the friction coe?cient exceeds a value of . At the end of the last load step the motor and water supply are turned o? and the reference for the clearance measurements is rechecked. Tests are performed at two speeds of 1500 and 3000 rpm corresponding to average sliding velocities of and m/s, respectively and each test is repeated at least three times. 4. Results and discussion As a ?rst step the validity of the theoretical model in Ref. [12] was examined by paring the theoretical and experimental results of bearing clearance versus bearing load for a unidirectional partialLST bearing. The results are shown in ?gure 6 for the two speeds of 1500 and 3000 rpm where the solid and dashed lines correspond to the model and experiment, respectively. As can be seen, the agreement between the model and the experiment is good, with di?erences of less than 10%, as long as the load is above 150 N. At lower loads the measured experimental clearances are much larger than the model predictions, particularly at the higher speed of 3000 rpm where at 120 N the measured clearance is 20 lm, which is about 60% higher than the predicted value. It turns out that the bination of such large clearances and relatively low viscosity of the water may result in turbulent ?uid ?lm. Hence, the assumption of laminar ?ow on which the solution of the Reynolds equation in Ref. [12] is based may be violated making the model invalid especially at the higher speed and lowest load. In order to be consistent with the model of Ref. [12] it was decided to limit further parisons to loads above 150 N. It should be noted here that the ?rst attempts to test the baseline untextured bearing with the original surface ?nish of Ra= lm on both the stator and rotor failed due to extremely high friction even at the lower loads. On the other hand the partialLST bearing ran smoothly throughout the load range. It was found that the postLST lapping to pletely remove about 2 lm height bulges, which are formed during texturing around the rims of the dimples, resulted in a slightly rougher surface with Ra= lm. Hence, the baseline untextured stator was also lapped to the same rough ness of the partialLST stator and all subsequent tests were performed with the same Ra value of lm for all the tested stators. The rotor surface roughness remained, the original one namely, lm. Figure 7 presents the experimental results for the clearance as a function of the load for a partialLST unidirectional bearing (see stator in ?gure 4(a)) and a baseline untextured bearing. The parison is made at the two speeds of 1500 and 3000 rpm. The area density of the dimples in the partialLST bearing is Sp= and the textured portion is a 188。can cause an early failure． Contaminated lubricant is often more difficult to detect than misalignment or creep． Contamination shows as premature wear． Solid contaminants bee an abrasive in the lubricant． In addition。突出表現(xiàn)在，單向和雙向定向部分反演軸承與一個基線的關(guān)系， 激光表面 微觀造型與無微觀造型軸承的比較顯示 好處在于，增加了清理和減少摩擦。 在平行滑動面可以得到一個穩(wěn)定的，有足夠的承載能力的油膜，例如，宏觀或微觀表面結(jié)構(gòu)就是不同類型。開口粗糙度的概念既[ 9 ]是基于有效地清除，減少在滑動方向和在這方面是相同的部分激光表面微造型概念所描述的標(biāo)準(zhǔn)。這些簡單的平行推力軸承，通常發(fā)現(xiàn)，在密封泵少的地方抽液是用來作為潤滑劑的軸 承。模型的紋理平行滑塊是發(fā)達(dá)國家和作用的表面紋理對承載能力進(jìn)行了分析。 [ 12 ]通過測試的實際推力軸承且與沒有表面微觀造型的軸承比較，表現(xiàn)反演軸承與該理論預(yù)測與性能標(biāo)準(zhǔn)的差異。人們發(fā)現(xiàn)，有著微觀表面造型的滑動面的油壓被分開是與滑動速度 U、液體粘度 1 和外部負(fù)載 W有關(guān) [ 12 ]認(rèn)為，有一個最佳的比例參數(shù) 存在能使微觀表面造型提供最大的無量綱負(fù)載。舉例說明，在 SP= 比例α = 時是α =1 時的三倍的的承載能力。每個墊有一個長寬比 時，其寬度是衡量沿線平均直徑定子。該激光毛化參數(shù)以下 ?？梢钥闯?，從圖 2 這兩種價值觀應(yīng)產(chǎn)生承載能力不同，接近最高的理論 試驗臺是顯示 schematically 在圖 5 。軸向載荷是所提供的手段，對絕對的權(quán)重杠桿作用，是衡量一個第二負(fù)荷單元。電腦是用來收集和處理數(shù)據(jù)上線。軸向負(fù)荷增加的步驟 40 N 和每個負(fù)載的步驟是維持 5 分鐘之后，穩(wěn)定的摩擦系數(shù)在一穩(wěn)定狀態(tài)的價值。測試是在兩種速度的 1500 和 3000 RPM 的相應(yīng)的平均滑動速度 和 米 /秒，分別和每個測試重復(fù)至少 3 次 第四章 成果與討論 作為第一步的有效性的理論模型。結(jié)果表明 ，該組合，如此龐大的間隙和相對低粘度的水可能會導(dǎo)致湍流流體膜。在另一方面部分 第 1 軸承，整個負(fù)荷范圍順利。圖 7 給出了實 驗結(jié)果為清除作為一個功能負(fù)荷為局部反演單向軸承（見定子在圖 4 （ a ） ）和基線無微觀造型軸承。很顯然，從圖 7 部分 第 1 軸承運轉(zhuǎn)大幅清拆比無微觀造型軸承。 圖 8 給出的結(jié)果為雙向軸承（見定子在圖 4 （ b ）款） 。這些價值觀所代表的減少之間的關(guān) br 33和 10 ％相比，單向的情況。無微觀造型的的摩擦系數(shù)大得多比他們大的多，即第 1 軸承。在速度上獲得了類似的結(jié)果， 3000 每分鐘轉(zhuǎn)速（圖 10 ） ，但水平的摩擦系數(shù)是有點高，由于較高的速度。 然而，當(dāng)事后的調(diào)查分析提供出寶貴的信息時，最好首先通過正確地選定軸承來完全避免失效的發(fā)生。由環(huán)境和污染 所產(chǎn)生的軸承失效是可以預(yù)防的，而且通過簡單的肉眼觀察是可以確定產(chǎn)生這類失效的原因。剝蝕的特征是在軸承圈滾道上留有由沖擊載荷或不正確的安裝產(chǎn)生的壓痕。 類似的一種缺陷是當(dāng)軸承不旋轉(zhuǎn)時由于滾珠在 軸承圈間振動而產(chǎn)生的橢圓形壓痕。與剝蝕不同，低荷振蝕的特征通常是由于微振磨損腐蝕在潤滑劑中會產(chǎn)生