【正文】 但 ABEC 等級并不能反映其他軸承特性，如軸承圈質(zhì)量、粗糙度、噪聲等。軸承每旋轉(zhuǎn)一周高頻不規(guī)則變化出現(xiàn) 60~300次，它表明軸承上存在著密集的振痕或大面積的粗糙不平。軸承每轉(zhuǎn)一周這種不規(guī)則變化可出現(xiàn)~10 次，它們是由各種干涉（例如 軸承圈滾道上的凹坑 ）引起的。 17 軸承缺陷可以通過其頻率特性進一步加以鑒定。測量噪聲的單位為 anderon。 噪聲是反映軸承質(zhì)量的一個指標。 一旦軸承受到污染，潤滑劑就要變質(zhì)，運行噪聲也隨之變大。同樣，機床主軸只能容許最小的振擺，以保證切削精度。保持架的尺寸誤差和軸承圈與滾珠的偏心都會引起 NRR。另外，不同的潤滑劑的噪聲特性也不一樣。 這可以在選用過程中通過考慮關(guān)鍵性能特征來實現(xiàn)。相比之下，帶狀或冠狀保持架能較容易地使?jié)櫥瑒┑竭_全部表面。污染的特 征是使軸承過早的出現(xiàn)磨損。這個問題是由于安裝不正確或公差不正確或軸承安裝現(xiàn)場的垂直度不夠造成的。 蠕動的明顯特征是劃痕、擦痕或軸與內(nèi)圈的顏色變化。另外，如果這個問題是由于載荷過大造成的， 就應(yīng)該采用抗載能力更強或其他結(jié)構(gòu)的軸承。 材料過早出現(xiàn)疲勞破壞是由重載后過大的預(yù)載引起的。 造成軸承卡住的原因 是缺少內(nèi)隙、潤滑不當和載荷過大。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 淡紅色。 類似的一種缺陷是當軸承不旋轉(zhuǎn)時由于滾珠在軸承圈間振動而產(chǎn)生的橢圓形壓痕。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。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。 然而，當事后的調(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。但是一個被損壞的軸承，會留下它為什么被損壞 的線索。t by artificial to participate in most, get from CAPP database in system directly. （ 5） . The dependability of the dependability maximization numerical control lathe has been the major indicator that users cared about most all the time . The numerical control system will adopt the circuit chip of higher integrated level , will utilize the extensive or super largescale specialpurpose and posite integrated circuit, in order to reduce the quantity of the ponents and parts , to improve dependability . Through the function software of the hardware, in order to meet various kinds of demands for controlling the function, adopt the module , standardization , universalization and seriation of the structure lathe noumenonn of the hardware at the same time , make not only improve the production lot of the hardware but also easy to is it produce to anize and quality check on.. Still through operating and starting many kinds of diagnostic programs of diagnosing , diagnosing , diagnosing offline online etc. automatically, realize that diagnoses and reports to the police the trouble to hardware , software and various kinds of outside equipment in the system. Utilize the warning suggestion, fix a breakdown in time。 Transfer vertically to the tower machining center and transfer 。s knowledge plays is more outstanding , and the machine tool industry is regarded as the foundation of the manufacturing industry of the machine, its key position and strategic meaning are more obvious. Within 19911994 years, the economic recession of the world, expensive FMS, CIMS lowers the temperature, among 19952021 years, the international economy increases at a low speed, according to requisition for NC lathe and the world four major international lathes exhibition in order to boost productivity of users of various fields of present world market (EMO , IMTS , JIMTOF , China CIMT of Japan of . of Europe), have the analysis of the exhibit, there are the following several points mainly in the technical research of NC lathe in our times: （ 1）、 Pay more attention to new technology and innovation Worldwide , are launching the new craft , new material , new structure , new unit , research and development of the new ponent in a more costeffective manner, developmental research of for instance new cutter material , the new electric main shaft of main shaft structure , high speed , highspeed straight line electrical machinery ,etc.. Regard innovating in improvement of the processing technology as the foundation, for process ultra and hard difficult to cut material and special posite and plicated part , irregular curved surface ,etc. research and develop new lathe variety constantly. （ 2）、 Improve the precision and research of machine tooling 7 In order to improve the machining accuracy of the machining center , are improving rigidity of the lathe , reduction vibration constantly, dispel hotly and out of shape, reduce the noise , improve the precision of localization of NC lathe , repeat precision , working dependability , stability , precision keeping, world a lot of country carry on lathe hot error , lathe sport and load out of shape software of error pensate technical research, take precision pensate , software pensate measure improve , some may make this kind of error dispel 60% already. And is developing retrofit constantly, nanometer is being processed. （ 3）、 Improve the research of the machine tooling productivity World NC lathe, machining center and corresponding some development of main shaft , electrical machinery of straight line , measuring system , NC system of high speed, under the prerequisite of boosting productivity. （ 4）、 What a lot of countries have already begun to the numerical control system melt intelligently, openly, study workedly A、 elligent research of the numerical control system Mainly showing in the following aspects: It is intelligent in order to pursue the efficiency of processing and process quality, the selfadaptation to the processing course is controlled, the craft parameter produces research automatically。目前主要采用超大規(guī)模集成元件、多層印刷電路板，采用三維安裝方法，使電子元器件得以高密度安裝，較大規(guī)?？s小系統(tǒng)的占有空間。通過硬件功能軟件化，以適應(yīng)各種控制功能的要求，同時采用硬件結(jié)構(gòu)機床本體的模塊化、標準化和通用化及系列化，使得既提高硬件生產(chǎn)批量，又便于組織生產(chǎn)和質(zhì)量把關(guān)。它是利用 CAD 繪制的零件加工圖樣，再經(jīng)計算機內(nèi)的刀具軌跡數(shù)據(jù)進行計算和后置處理，從而自動生成 NC 零件加工程序，以實現(xiàn) CAD 與 CAM 的集成。一旦出現(xiàn)故障時，立即采用停機等措施，并進行故障報警，提示發(fā)生故障的部位、原因等。數(shù)控系統(tǒng)由于采用了多 CPU 結(jié)構(gòu)和分級中斷控制方式，即可在一臺機床上同時進行零件加工和程序編制，實現(xiàn)所謂的“前臺加工，后臺編輯”。采用前饋控制技術(shù)，使追蹤滯后誤差大大減小，從而改善拐角切削的加工精度。 （ 1） .高速度、高精度化速度和精度是數(shù)控機床的兩個重要指標，它直接關(guān)系到加工效率和產(chǎn)品質(zhì)量。 復(fù)合加工中心，主要指五面復(fù)合加工，主軸頭可自動回轉(zhuǎn)，進行立，臥加工，在主軸自動回轉(zhuǎn)后，在水平和垂直方向?qū)崿F(xiàn)知道變換。 大型龍門式加工中心，主軸多為垂直設(shè)置，尤其使用于大型或形狀復(fù)雜的工件，像航空、航天工業(yè)及大型汽輪機上的某些零件的加工都需要用這類多坐標龍門式加工中心。臥式加工中心一般具有3— 5 個運動坐標軸，常見的是三個直線運動坐標軸和一個回轉(zhuǎn)運動坐標軸（回轉(zhuǎn)工作臺），它能在工件一次裝夾完成除安裝面和頂面以外的其余 4 個面的加工，最適合加工箱體類工件。目前開放式數(shù)控系統(tǒng)的體系結(jié)構(gòu)規(guī)范、通行規(guī)范、配置規(guī)范、運行平臺、數(shù)控系統(tǒng)功能庫 以及數(shù)控系統(tǒng)功能軟件開發(fā)工具等是當前研究的核心。并在不斷開發(fā)精細加工，納米加工。機床工業(yè)有世界經(jīng)濟相互促進和發(fā)展，進入 21 世界知識機警時代，人們的知識所起的作用更加突出，而機床工業(yè)作為機器制造業(yè)的基礎(chǔ)，其重點地位與戰(zhàn)略意義也更加明顯。在 1991— 1994 年間，世界經(jīng)濟衰退，昂貴的 FMS， CIMS 降溫， 1995— 2021 年間，世界經(jīng)濟在低速增長，根據(jù)當前世界市場各方面用戶為提高生產(chǎn)率對 NC 機床的要求以及世界四大國際機床展（歐洲的 EMO、美國的 IMTS、日本的 JIMTOF、中國的 CIMT）上展品的分析，當前世