氣門(mén)搖臂軸支座 加工工藝及銑Φ26面夾具設(shè)計(jì)

喜歡就充值下載吧。資料目錄下的全部文件，下載了全部有的哦 機(jī)械加工工序卡片產(chǎn)品型號(hào)1105型零（部）件圖號(hào)設(shè)計(jì)者：產(chǎn)品名稱柴油機(jī)零（部）件名稱柴油機(jī)氣門(mén)搖臂支座共 8 頁(yè)第 1 頁(yè)車間工序號(hào)工序名稱材料牌號(hào)機(jī)加1粗銑HT200毛坯種類毛坯外型尺寸每毛坯可制件數(shù)每臺(tái)件數(shù)鑄件11設(shè)備名稱設(shè)備型號(hào)設(shè)備編號(hào)同時(shí)加工件數(shù)銑床X521夾具編號(hào)夾具名稱切削液專用夾具不用工位器具編號(hào)工位器具名稱工序工時(shí)準(zhǔn)終單件0.046工步號(hào)工 步 內(nèi) 容工藝裝備（含：刀具、量具、專用工具）主軸轉(zhuǎn)速r/min 切削速度m/min進(jìn)給量mm/r切削深度mm進(jìn)給次數(shù)工 步 工 時(shí)1粗銑底平面，銑尺寸39mm至42.mm三面刃銑刀，游標(biāo)卡尺，專用夾具7501171.2621機(jī)動(dòng)輔助機(jī)械加工工序卡片產(chǎn)品型號(hào)1105型零（部）件圖號(hào)設(shè)計(jì)者：產(chǎn)品名稱柴油機(jī)零（部）件名稱柴油機(jī)氣門(mén)搖臂軸支座共 8 頁(yè)第 2 頁(yè)車間工序號(hào)工序名稱材料牌號(hào)機(jī)加2粗銑HT200毛坯種類毛坯外型尺寸每毛坯可制件數(shù)每臺(tái)件數(shù)鑄件11設(shè)備名稱設(shè)備型號(hào)設(shè)備編號(hào)同時(shí)加工件數(shù)銑床X521夾具編號(hào)夾具名稱切削液通用夾具不用工位器具編號(hào)工位器具名稱工序工時(shí)準(zhǔn)終單件0.022工步號(hào)工 步 內(nèi) 容工藝裝備（含：刀具、量具、專用工具）主軸轉(zhuǎn)速r/min 切削速度m/min進(jìn)給量mm/r切削深度mm進(jìn)給次數(shù)工 步 工 時(shí)1粗銑圓柱上端面。三面刃銑刀，通用夾具，游標(biāo)卡尺7501171.262.51機(jī)動(dòng)輔助 機(jī)械加工工序卡片產(chǎn)品型號(hào)1105型零（部）件圖號(hào)設(shè)計(jì)者：產(chǎn)品名稱柴油機(jī)零（部）件名稱柴油機(jī)氣門(mén)搖臂軸支座共 8 頁(yè)第 3 頁(yè)車間工序號(hào)工序名稱材料牌號(hào)機(jī)加3粗銑HT200毛坯種類毛坯外型尺寸每毛坯可制件數(shù)每臺(tái)件數(shù)鑄件11設(shè)備名稱設(shè)備型號(hào)設(shè)備編號(hào)同時(shí)加工件數(shù)銑床X521夾具編號(hào)夾具名稱切削液通用夾具不用工位器具編號(hào)工位器具名稱工序工時(shí)準(zhǔn)終單件0.15工步號(hào)工 步 內(nèi) 容工藝裝備（含：刀具、量具、專用工具）主軸轉(zhuǎn)速r/min 切削速度m/min進(jìn)給量mm/r切削深度mm進(jìn)給次數(shù)工 步 工 時(shí)1粗銑28圓柱上端面端面。三面刃銑刀，通用夾具，游標(biāo)卡尺7501181.262.01機(jī)動(dòng)輔助2粗銑26圓柱上端面。三面刃銑刀，通用夾具，游標(biāo)卡尺7501181.262.513粗銑28圓柱下端面端面。三面刃銑刀，通用夾具，游標(biāo)卡尺7501181.262.014粗銑26圓柱下端面。三面刃銑刀，通用夾具，游標(biāo)卡尺7501181.262.51 機(jī)械加工工序卡片產(chǎn)品型號(hào)1105型零（部）件圖號(hào)設(shè)計(jì)者：產(chǎn)品名稱柴油機(jī)零（部）件名稱柴油機(jī)氣門(mén)搖臂軸支座共 8 頁(yè)第 4 頁(yè)車間工序號(hào)工序名稱材料牌號(hào)機(jī)加4精銑HT200毛坯種類毛坯外型尺寸每毛坯可制件數(shù)每臺(tái)件數(shù)鑄件11設(shè)備名稱設(shè)備型號(hào)設(shè)備編號(hào)同時(shí)加工件數(shù)銑床X521夾具編號(hào)夾具名稱切削液專用夾具不用工位器具編號(hào)工位器具名稱工序工時(shí)準(zhǔn)終單件0.116工步號(hào)工 步 內(nèi) 容工藝裝備（含：刀具、量具、專用工具）主軸轉(zhuǎn)速r/min 切削速度m/min進(jìn)給量mm/r切削深度mm進(jìn)給次數(shù)工 步 工 時(shí)1精銑底平面，保證尺寸39mm 。三面刃銑刀，游標(biāo)卡尺，專用夾具30047.10.8040.51機(jī)動(dòng)輔助 機(jī)械加工工序卡片產(chǎn)品型號(hào)1105型零（部）件圖號(hào)設(shè)計(jì)者：產(chǎn)品名稱柴油機(jī)零（部）件名稱柴油機(jī)氣門(mén)搖臂軸支座共 8 頁(yè)第5頁(yè)車間工序號(hào)工序名稱材料牌號(hào)機(jī)加5鉆HT200毛坯種類毛坯外型尺寸每毛坯可制件數(shù)每臺(tái)件數(shù)鑄件11設(shè)備名稱設(shè)備型號(hào)設(shè)備編號(hào)同時(shí)加工件數(shù)鉆床Z5251夾具編號(hào)夾具名稱切削液通用夾具不用工位器具編號(hào)工位器具名稱工序工時(shí)準(zhǔn)終單件0.3工步號(hào)工 步 內(nèi) 容工藝裝備（含：刀具、量具、專用工具）主軸轉(zhuǎn)速r/min 切削速度m/min進(jìn)給量mm/r切削深度mm進(jìn)給次數(shù)工 步 工 時(shí)1鉆11小孔成。高速鋼錐柄麻花鉆，游標(biāo)卡尺，5450.300.265.51機(jī)動(dòng)輔助 機(jī)械加工工序卡片產(chǎn)品型號(hào)1105型零（部）件圖號(hào)設(shè)計(jì)者：產(chǎn)品名稱柴油機(jī)零（部）件名稱柴油機(jī)氣門(mén)搖臂軸支座共 8 頁(yè)第6 頁(yè)車間工序號(hào)工序名稱材料牌號(hào)機(jī)加6精銑HT200毛坯種類毛坯外型尺寸每毛坯可制件數(shù)每臺(tái)件數(shù)鑄件11設(shè)備名稱設(shè)備型號(hào)設(shè)備編號(hào)同時(shí)加工件數(shù)銑床X521夾具編號(hào)夾具名稱切削液專用夾具不用工位器具編號(hào)工位器具名稱工序工時(shí)準(zhǔn)終單件0.097工步號(hào)工 步 內(nèi) 容工藝裝備（含：刀具、量具、專用工具）主軸轉(zhuǎn)速r/min 切削速度m/min進(jìn)給量mm/r切削深度mm進(jìn)給次數(shù)工 步 工 時(shí)1精銑28圓柱上端面三面刃銑刀，游標(biāo)卡尺，專用夾具30047.10.8040.51機(jī)動(dòng)輔助2翻面精銑28圓柱另一端面三面刃銑刀，游標(biāo)卡尺，專用夾具30047.10.8040.51 機(jī)械加工工序卡片產(chǎn)品型號(hào)1105型零（部）件圖號(hào)設(shè)計(jì)者：產(chǎn)品名稱柴油機(jī)零（部）件名稱柴油機(jī)氣門(mén)搖臂軸支座共 8 頁(yè)第7頁(yè)車間工序號(hào)工序名稱材料牌號(hào)機(jī)加7鉆HT200毛坯種類毛坯外型尺寸每毛坯可制件數(shù)每臺(tái)件數(shù)鑄件85404011設(shè)備名稱設(shè)備型號(hào)設(shè)備編號(hào)同時(shí)加工件數(shù)鉆床Z30251夾具編號(hào)夾具名稱切削液專用夾具不用工位器具編號(hào)工位器具名稱工序工時(shí)準(zhǔn)終單件1工步號(hào)工 步 內(nèi) 容工藝裝備（含：刀具、量具、專用工具）主軸轉(zhuǎn)速r/min 切削速度m/min進(jìn)給量mm/r切削深度mm進(jìn)給次數(shù)工 步 工 時(shí)1鉆孔 至高速鋼錐柄麻花鉆，專用夾具40017.220.267機(jī)動(dòng)輔助2擴(kuò)孔至15.8鉆孔高速鋼錐柄麻花鉆，專用夾具63028.360.50.93鉸孔高速鋼錐柄麻花鉆，內(nèi)徑百分尺，專用夾具1256.660.130.14鉆至高速鋼錐柄麻花鉆，專用夾具40019.20.2685擴(kuò)孔至17.8高速鋼錐柄麻花鉆，專用夾具63034.60.50.96鉸孔高速鋼錐柄麻花鉆，內(nèi)徑百分尺，專用夾具1257.30.130.1機(jī)械加工工藝過(guò)程卡片產(chǎn)品型號(hào)1105型零（部）件圖號(hào)共 1 頁(yè)產(chǎn)品名稱柴油機(jī)零（部）件名稱氣門(mén)搖臂支座第 1 頁(yè)材料牌號(hào)HT200毛坯種類鑄件毛坯外型尺寸每毛坯可制件數(shù)每 臺(tái) 件 數(shù)1備 注工序號(hào)工序名稱工 序 內(nèi) 容車間工段設(shè) 備工 藝 裝 備工 時(shí)準(zhǔn)終單件1銑粗銑底平面，以上圓柱端面定位，銑尺寸39mm至42mm。機(jī)加X(jué)52專用夾具、錯(cuò)齒三面刃銑刀、0.0462銑粗銑圓柱上端面，以底面定位。銑尺寸39mm至39.5mm機(jī)加X(jué)52通用夾具、錯(cuò)齒三面刃銑刀0.0223銑粗銑圓柱兩端面，銑尺寸mm至38mm。粗銑圓柱端面，保證軸向尺寸16mm。機(jī)加X(jué)52通用夾具錯(cuò)齒、三面刃銑刀0.154銑精銑底平面，以上圓柱端面定位，保證尺寸39mm。機(jī)加X(jué)52專用夾具錯(cuò)齒、三面刃銑刀0.1165鉆鉆小孔成機(jī)加Z525通用夾具、錐柄麻花鉆0.36銑精銑圓柱端面成，保證尺寸mm機(jī)加X(jué)52專用夾具錯(cuò)齒、三面刃銑刀0.0977鉆鉆擴(kuò)鉸、孔成，保證兩孔中心距 mm，保證中心與底平面距離mm，中心與底平面距離mm。機(jī)加Z525專用夾具、錐柄麻花鉆18倒角、兩孔兩端倒角。9鉆鉆孔成機(jī)加Z525專用夾具、錐柄麻花鉆0.0110鉗去毛刺、銳邊。11檢終檢、入庫(kù)。0.030.3編號(hào)無(wú)錫太湖學(xué)院畢業(yè)設(shè)計(jì)（論文）相關(guān)資料題目： 搖臂零件工藝及工裝設(shè)計(jì) 信機(jī) 系 機(jī)械工程及自動(dòng)化專業(yè)學(xué) 號(hào)： 0923140學(xué)生姓名： 司舒暉 指導(dǎo)教師： 許文（職稱：副教授） 2013年5月25日目 錄一、畢業(yè)設(shè)計(jì)（論文）開(kāi)題報(bào)告二、畢業(yè)設(shè)計(jì)（論文）外文資料翻譯及原文三、學(xué)生“畢業(yè)論文（論文）計(jì)劃、進(jìn)度、檢查及落實(shí)表”四、實(shí)習(xí)鑒定表無(wú)錫太湖學(xué)院畢業(yè)設(shè)計(jì)（論文）開(kāi)題報(bào)告題目： 搖臂零件工藝及工裝設(shè)計(jì) 信機(jī) 系 機(jī)械工程及自動(dòng)化 專業(yè)學(xué) 號(hào)： 0923140 學(xué)生姓名： 司舒暉 指導(dǎo)教師： 許文 （職稱：副教授 ） 2012年11月14日 課題來(lái)源自擬題目科學(xué)依據(jù)（1）課題科學(xué)意義隨著現(xiàn)代社會(huì)進(jìn)程的加快，柴油機(jī)發(fā)揮的社會(huì)作用不可估量，特別是在社會(huì)工業(yè)化之后，柴油機(jī)作為動(dòng)力內(nèi)燃機(jī)的一種，在社會(huì)的各個(gè)領(lǐng)域無(wú)處不在，為社會(huì)創(chuàng)造著巨大的效益。在這領(lǐng)域中，柴油機(jī)所發(fā)揮的作用也是不盡相同，所以根據(jù)作用的需要，柴油機(jī)也被設(shè)計(jì)出了很多種型號(hào)，各種型號(hào)功率不同，發(fā)揮的作用大小也就不一樣，創(chuàng)造出的價(jià)值也不一樣。但是柴油機(jī)的污染排放也是一個(gè)不小的社會(huì)問(wèn)題，隨著社會(huì)的發(fā)展，人類對(duì)生活質(zhì)量要求的提高，而高污染排放的柴油機(jī)必定不能滿足人類的這一生活需求，但是柴油機(jī)已經(jīng)是社會(huì)發(fā)展不可缺少的一個(gè)重要零部分，徹底取代柴油機(jī)在目前的技術(shù)條件下似乎還不太可能。（2）研究狀況及其發(fā)展前景：隨著社會(huì)的需要，柴油機(jī)生產(chǎn)數(shù)量將不斷的增長(zhǎng)，而氣門(mén)搖臂軸支座是柴油機(jī)上不可或缺的零件，也就是意味著氣門(mén)搖臂軸支座的生產(chǎn)數(shù)量將是與日俱增，為了創(chuàng)造出更大的效益，設(shè)計(jì)出輕便，經(jīng)久耐用，便于生產(chǎn)的氣門(mén)搖臂軸支座這一零件是很有必要的。柴油機(jī)具有熱效率高的顯著優(yōu)點(diǎn)，其應(yīng)用范圍越來(lái)越廣。隨著強(qiáng)化程度的提高，柴油機(jī)單位功率的重量也顯著降低。為了節(jié)能，各國(guó)都在注重改善燃燒過(guò)程，研究燃用低質(zhì)燃油和非石油制品燃料。此外，降低摩擦損失、廣泛采用廢氣渦輪增壓并提高增壓度、進(jìn)一步輕量化、高速化、低油耗、低噪聲和低污染，都是柴油機(jī)的重要發(fā)展方向。研究?jī)?nèi)容了解氣門(mén)搖臂零件的工作原理，國(guó)內(nèi)外的研究發(fā)展現(xiàn)狀； 完成氣門(mén)搖臂零件的總體方案設(shè)計(jì)； 完成有關(guān)零部件的選型計(jì)算、結(jié)構(gòu)強(qiáng)度校核； 熟練掌握計(jì)算機(jī)CAD繪圖軟件，并繪制裝配圖和零件圖紙，折合A0不少于2.5張； 完成說(shuō)明書(shū)的撰寫(xiě)，并且翻譯外文資料1篇。擬采取的研究方法、技術(shù)路線、實(shí)驗(yàn)方案及可行性分析1）技術(shù)路線首先根據(jù)氣門(mén)搖臂零件的特殊性對(duì)其造型等方面的設(shè)計(jì)需求進(jìn)行分析，從整體上把握其設(shè)計(jì)原則；然后對(duì)不同的功能區(qū)域進(jìn)行單獨(dú)的研究分析，總結(jié)出符合工程學(xué)要求的設(shè)計(jì)理論；最后將整體的設(shè)計(jì)分析和每一部分的設(shè)計(jì)相結(jié)合，尋找有效的結(jié)合點(diǎn)并進(jìn)行統(tǒng)一協(xié)調(diào)，最終設(shè)計(jì)出高質(zhì)量、高檔次的產(chǎn)品。（2）研究方法 測(cè)試出氣門(mén)搖臂各零件的尺寸、剛度，獲得大量的實(shí)驗(yàn)數(shù)據(jù)。 對(duì)實(shí)驗(yàn)數(shù)據(jù)進(jìn)行分析處理，為建立氣門(mén)搖臂力學(xué)模型與分析作了必要的準(zhǔn)備。（3）實(shí)驗(yàn)方案 確定具體設(shè)計(jì)方案：零件的工藝分析及生產(chǎn)類型的確定，零件的工藝分析研究計(jì)劃及預(yù)期成果（1）研究計(jì)劃：2012年10月28日-2012年11月16日：學(xué)習(xí)并翻譯一篇與畢業(yè)設(shè)計(jì)相關(guān)的英文材料2012年11月20日-2013年1月20日：按照任務(wù)書(shū)要求查閱論文相關(guān)參考資料，填寫(xiě)畢業(yè)設(shè)計(jì)開(kāi)題報(bào)告書(shū)。2013年1月25日-2013年2月10日：填寫(xiě)畢業(yè)實(shí)習(xí)報(bào)告。2013年2月20日-2013年3月10日：按照要求修改畢業(yè)設(shè)計(jì)開(kāi)題報(bào)告。2013年3月19日-2013年3月30日：氣門(mén)搖臂軸支座銑18孔端面的夾具結(jié)構(gòu)設(shè)計(jì)。2013年4月1日-2013年4月25日：CAD繪圖。2013年4月26日-2013年5月21日：畢業(yè)論文撰寫(xiě)和修改工作。（2）預(yù)期成果：我國(guó)市場(chǎng)前景廣闊，產(chǎn)品質(zhì)量性能逐漸滿足要求，因此產(chǎn)品的發(fā)展必須由單純的追求技術(shù)上的完善，轉(zhuǎn)向產(chǎn)品外觀質(zhì)量的提高，放到與技術(shù)改進(jìn)放到同等重要的位置，通過(guò)本課題的研究，產(chǎn)品必定以合理的色彩以及人性化的結(jié)構(gòu)方式提高自己的附加值，吸引到更多地客戶，加大自己產(chǎn)品的市場(chǎng)占有率，提高在行業(yè)中的競(jìng)爭(zhēng)力。特色或創(chuàng)新之處1通用性好，氣門(mén)搖臂軸支座銑18孔端面在設(shè)計(jì)過(guò)程中，考略到通用性，因此留有余地，因此除搬運(yùn)外，還可以焊接噴漆等。2工作效率，提高了勞動(dòng)生產(chǎn)效率，同時(shí)也降低了成本。已具備的條件和尚需解決的問(wèn)題（1）.夾具的構(gòu)造應(yīng)與其用途和生產(chǎn)規(guī)模相適應(yīng)，正確處理好質(zhì)量、效率、方便性與經(jīng)濟(jì)性四者的關(guān)系。 （2）.保證使用方便，要便于裝卸、便于夾緊、便于測(cè)量、便于觀察、便于排屑排液、便于安裝運(yùn)輸，保證安全第一。 （3）.注意結(jié)構(gòu)工藝，對(duì)加工、裝配、維修通盤(pán)考慮，降低成本。指導(dǎo)教師意見(jiàn) 指導(dǎo)教師簽名：年 月 日教研室（學(xué)科組、研究所）意見(jiàn) 教研室主任簽名： 年 月 日系意見(jiàn) 主管領(lǐng)導(dǎo)簽名： 年 月 日英文原文Experimental investigation of laser surface textured parallel thrust bearingsPerformance enhancements by laser surface texturing (LST) of parallel-thrust bearings is experimentally investigated. Testresults are compared with a theoretical model and good correlation is found over the relevant operating conditions. A compari-son of the performance of unidirectional and bi-directional partial-LST bearings with that of a baseline, untextured bearing ispresented showing the benets of LST in terms of increased clearance and reduced friction.KEY WORDS: uid lm bearings, slider bearings, surface texturing1. IntroductionThe classical theory of hydrodynamic lubrication yields linear (Couette) velocity distribution with zero pressure gradients between smooth parallel surfaces under steady-state sliding. This results in an unstable hydrodynamic lm that would collapse under any external force acting normal to the surfaces. However, experience shows that stable lubricating lms can develop between parallel sliding surfaces, generallybecause of some mechanism that relaxes one or more of the assumptions of the classical theory.A stable uid lm with sucient load-carrying capacity in parallel sliding surfaces can be obtained, for example, with macro or micro surface structure of dierent types. These include waviness 1 and protruding microasperities 24. A good literature review on the subject can be found in Ref. 5. More recently, laser surface texturing (LST) 68, as well as inlet roughening by longitudinal or transverse grooves 9 were suggested to provide load capacity in parallel sliding. The inlet roughness concept of Tonder 9 is based on eective clearance reduction in the slidingdirection and in this respect it is identical to the par- tial-LST concept described in ref. 10 for generating hydrostatic eect in high-pressure mechanical seals.Very recently Wang et al. 11 demonstrated experimentally a doubling of the load-carrying capacity for the surface- texture design by reactive ion etching of SiC parallel-thrust bearings sliding in water. These simple parallel thrust bearings are usually found in seal-less pumps where the pumped uid is used as the lubricant for the bearings. Due to the parallel sliding their performance is poorer than more sophisticated tapered or stepped bearings. Brizmer et al. 12 demon-strated the potential of laser surface texturing in the form of regular micro-dimples for providing load-carrying capacity with parallel-thrust bearings. A model of a textured parallel slider was developed and the eect of surface texturing on load-carrying capacitywas analyzed. The optimum parameters of the dimples were found in order to obtain maximum load-carrying capacity. A micro-dimple collective eect was identi-ed that is capable of generating substantial load-carrying capacity, approaching that of optimumconventional thrust bearings. The purpose of the present paper is to investigate experimentally the validity of the model described in Ref. 12 by testing practical thrust bearings and comparing the performance of LST bearings with that of the theoretical predictions and with the performance of standard non-texturedbearings2. BackgroundA cross section of the basic model that was analyzed in Ref. 12 is shown in figure 1. A slider having a width B is partially textured over a portion Bp =B of its width. The textured surface consists of multiple dimples with a diameter，depthand area density Sp. As a result of the hydrodynamic pressure generated by the dimples the sliding surfaces will be separated by a clearancedepending on the sliding velocity U, the uid viscosity l and the external loadIt was found in Ref. 12 that an optimum ratio exists for the parameter that provides maximum dimensionless load-carrying capacity where L isthe bearing length, and this optimum value is hp=1.25. It was further found in Ref. 12 that an optimum value exists for the textured portion a depending onthe bearing aspect ratio L/B. This behavior is shown in gure 2 for a bearing with L/B = 0.75 at various values of the area density Sp. As can be seen in the range of Sp values from 0.18 to 0.72 the optimum a value varies from 0.7 to 0.55, respectively. It can also be seen from gure 2 that for a 0.85 no optimum value exists for Sp and the maximum load W increases with increasing Sp. Hence, the largest area density that can be practically obtained with the laser texturing is desired. It is also interesting to note from gure 2 the advantage of partial-LST (a 1) over the full LST (a = 1) for bearing applications. At Sp= 0.5, for example, the load W at a = 0.6 is about three times higher than its value at a = 1. A full account of this behavior is given in Ref. 12.3. ExperimentalThe tested bearings consist of sintered SiC disks 10 mm thick, having 85 mm outer diameter and 40 mm inner diameter. Each bearing (see gure 3) comprises a at rotor (a) and a six-pad stator (b). The bearings were provided with an original surface nishby lapping to a roughness average Ra= 0.03 lm. Each pad has an aspect ratio of 0.75 when its width is measured along the mean diameter of the stator. The photographs of two partial-LST stators are shown in gure 4 where the textured areas appear as brighter matt surfaces. The rst stator indicated (a) is a unidirectional bearing with the partial-LST adjacent to the leading edge of each pad, similar to the model shown in gure 1. The second stator (b) is a bi-directional version of a partial-LST bearing having two equal textured portions, a/2, on each of the pad ends. The laser texturing parameters were the following; dimple depth, dimple diameter and dimple area density Sp= 0.60.03. These dimple dimensions were obtained with 4 pulses of 30 ns duration and 4 mJ each using a 5 kHz pulsating Nd:YAG laser. The textured portion of the unidirectional bearing was a= 0.73 and that of the bi-directional bearing was a= 0.63. As can be seen from gure 2 both these a values should produce load-carrying capacity vary close to the maximum theoretical value.The test rig is shown schematically in gure 5. Anelectrical motor turns a spindle to which an upper holder of the rotor is attached. A second lower holder of the stator is xed to a housing, which rests on a journal bearing and an axial loading mechanism that 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 on-line measurements of the clearance change between rotor and stator as the hydrodynamic eects 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 re-circulated. A thermocouple adjacent tothe 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 on-line. Hence,the instantaneous clearance, friction coecient, 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 coecient ata steady-state 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 coecient exceeds a value of 0.35. 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 1500and 3000 rpm corresponding to average sliding velocities of 4.9 and 9.8 m/s, respectively and each test is repeated at least three times.4. Results and discussionAs a rst step the validity of the theoretical model in Ref. 12 was examined by comparing the theoretical and experimental results of bearing clearance versus bearing load for a unidirectional partial-LST 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 dierences 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 combination 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 comparisons 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= 0.03 lm on both the stator and rotor failed due to extremely high friction even at the lower loads. On the other hand the partial-LST bearing ran smoothly throughout the load range. It was found that the post-LST lapping to completely 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= 0.04 lm. Hence, the baseline untextured stator was also lapped to the same rough-ness of the partial-LST stator and all subsequent tests were performed with the same Ra value of 0.04 lm for all the tested stators. The rotor surface roughnessremained, the original one namely, 0.03 lm. Figure 7 presents the experimental results for the clearance as a function of the load for a partial-LST unidirectional bearing (see stator in gure 4(a) and a baseline untextured bearing. The comparison is made at the two speeds of 1500 and 3000 rpm. The area density of the dimples in the partial-LST bearing is Sp= 0.6 and the textured portion is a 0:734. The load range extends from 160 to 460 N. The upper load was determined by the test-rig limitation that did not permit higher loading. It is clear from gure 7 that the partial-LST bearing operates at substantially larger clearances than the untextured bearing. At the maximum load of 460 N and speed of 1500 rpm the partial-LST bearing has a clearance of 6 lm while the untextured bearing clearance is only 1.7 lm. At 3000 rpm the clearances are 6.6and 2.2 lm for the LST and untextured bearings, respectively. As can be seen from gure 7 this ratio of about 3 in favor of the partial-LST bearing is maintained over the entire load range.Figure 8 presents the results for the bi-directionalbearing (see stator in gure 4(b). In this case the LST parameters are Sp 0:614 and a 0:633. The clearances of the bi-directional partial-LST bearing are lower compared to these of the unidirectional bearing at the same load. At 460 N load the clearance for the 1500 rpm is 4.1 lm and for the 3000 rpm it is 6 lm. These values represent a reduction of clearance between33 and 10% compared to the unidirectional case. However, as can be seen from gure 8 the performance of the partial-LST bi-directional bearing is still substantially better than that of the untextured bearing. The friction coecient of partial-LST unidirectional and bi-directional bearings was compared with that of the untextured bearing in gures 9 and 10 for the two speeds of 1500 and 3000 rpm, respectively. As can be seen the friction coecient of the two partial-LST bearings is very similar with slightly lower values in the case of the more ecient unidirectional bearing. The friction coecient of the untextured bearing ismuch larger compared to that of the LST bearings. At 1500 rpm (gure 9) and the highest load of 460 N the friction coecient of the untextured bearing is about 0.025 compared to about 0.01 for the LST bearings.At the lowest load of 160 N the values are about 0.06 for the untextured bearing and around 0.02 for the LST bearings. Hence, the friction values of the untextured bearing are between 2.5 and 3 times higher than the corresponding values for the partial-LST bearings over the entire load range. Similar results were obtained at the velocity of 3000 rpm (gure 10) but the level of the friction coecients is somewhat higherdue to the higher speed. The much higher friction of the untextured bearing is due to the much smaller clearances of this bearing (see gures 7 and 8) that result in higher viscous shear.Bearings fail for a number of reasons，but the most common are misapplication，contamination，improper lubricant，shipping or handling damage，and misalignment. The problem is often not difficult to diagnose because a failed bearing usually leaves telltale signs about what went wrongHowever，while a postmortem yields good information，it is better to avoid the process altogether by specifying the bearing correctly in The first placeTo do this，it is useful to review the manufacturers sizing guidelines and operating characteristics for the selected bearing.Equally critical is a study of requirements for noise, torque, and runout, as well as possible exposure to contaminants, hostile liquids, and temperature extremes. This can provide further clues as to whether a bearing is right for a job.1 Why bearings failAbout 40% of ball bearing failures are caused by contamination from dust, dirt, shavings, and corrosion. Contamination also causes torque and noise problems, and is often the result of improper handling or the application environmentFortunately, a bearing failure caused by environment or handling contamination is preventable，and a simple visual examination can easily identify the causeConducting a postmortem il1ustrates what to look for on a failed or failing bearingThen，understanding the mechanism behind the failure, such as brinelling or fatigue, helps eliminate the source of the problem.Brinelling is one type of bearing failure easily avoided by proper handing and assembly. It is characterized by indentations in the bearing raceway caused by shock loadingsuch as when a bearing is dropped-or incorrect assembly. Brinelling usually occurs when loads exceed the material yield point(350,000 psi in SAE 52100 chrome steel)It may also be caused by improper assembly, Which places a load across the racesRaceway dents also produce noise，vibration，and increased torque.A similar defect is a pattern of elliptical dents caused by balls vibrating between raceways while the bearing is not turningThis problem is called false brinelling. It occurs on equipment in transit or that vibrates when not in operation. In addition, debris created by false brinelling acts like an abrasive, further contaminating the bearing. Unlike brinelling, false binelling is often indicated by a reddish color from fretting corrosion in the lubricant.False brinelling is prevented by eliminating vibration sources and keeping the bearing well lubricated. Isolation pads on the equipment or a separate foundation may be required to reduce environmental vibration. Also a light preload on the bearing helps keep the balls and raceway in tight contact. Preloading also helps prevent false brinelling during transit.Seizures can be caused by a lack of internal clearance, improper lubrication, or excessive loading. Before seizing, excessive, friction and heat softens the bearing steel. Overheated bearings often change color，usually to blue-black or straw coloredFriction also causes stress in the retainer，which can break and hasten bearing failurePremature material fatigue is caused by a high load or excessive preloadWhen these conditions are unavoidable，bearing life should be carefully calculated so that a maintenance scheme can be worked outAnother solution for fighting premature fatigue is changing materialWhen standard bearing materials，such as 440C or SAE 52100，do not guarantee sufficient life，specialty materials can be recommended. In addition，when the problem is traced back to excessive loading，a higher capacity bearing or different configuration may be usedCreep is less common than premature fatigueIn bearingsit is caused by excessive clearance between bore and shaft that allows the bore to rotate on the shaftCreep can be expensive because it causes damage to other components in addition to the bearing0ther more likely creep indicators are scratches，scuff marks，or