【正文】 聲等級的劃分有助于工業(yè)標(biāo)準(zhǔn)的改進(jìn)。即用 um/rad 表示的軸承位移。和重復(fù)性振擺不同的是， NRR 是沒有辦法進(jìn)行補償?shù)?。潤滑劑中的固體雜質(zhì)就象磨粒一樣。如果這些條件不可避免，就應(yīng)仔細(xì)計算軸承壽命，以制定一個維護(hù)計劃。剝蝕通常是在載荷超過材料屈服極限時發(fā)生的。 the two angles are equal for a 90deg. Shaft angle. When gears are to be used to transmit motion between intersecting shaft, some of bevel gear is required. Although bevel gear are usually made for a shaft angle of 90 deg. They may be produced for almost any shaft angle. The teeth may be cast, milled, or generated. Only the generated teeth may be classed as accurate. In a typical bevel gear mounting, one of the gear is often mounted outboard of the bearing. This means that shaft deflection can be more pronounced and have a greater effect on the contact of teeth. Another difficulty, which occurs in predicting the stress in bevelgear teeth, is the fact the teeth are tapered. Straight bevel gears are easy to design and simple to manufacture and give very good results in service if they are mounted accurately and positively. As in the case of squr gears, however, they bee noisy at higher values of the pitchline velocity. In these cases it is often good design practice to go to the spiral bevel gear, which is the bevel counterpart of the helical gear. As in the case of helical gears, spiral bevel gears give a much smoother tooth action than straight bevel gears, and hence are useful where high speed are encountered. It is frequently desirable, as in the case of automotive differential applications, to have gearing similar to bevel gears but with the shaft offset. Such gears are called hypoid gears because their pitch surfaces are hyperboloids of revolution. The tooth action between such 8 gears is a bination of rolling and sliding along a straight line and has much in mon with that of worm gears. A shaft is a rotating or stationary member, usually of circular cross section, having mounted upon it such elementsas gears, pulleys, flywheels, cranks, sprockets, and other powertransmission elements. Shaft may be subjected to bending, tension, pression, or torsional loads, acting singly or in bination with one another. When they are bined, one may expect to find both static and fatigue strength to be important design considerations, since a single shaft may be subjected to static stresses, pletely reversed, and repeated stresses, all acting at the same time. The word “shaft” covers numerous variations, such as axles and spindles. Anaxle is a shaft, wither stationary or rotating, nor subjected to torsion load. A shirt rotating shaft is often called a spindle. When either the lateral or the torsional deflection of a shaft must be held to close limits, the shaft must be sized on the basis of deflection before analyzing the stresses. The reason for this is that, if the shaft is made stiff enough so that the deflection is not too large, it is probable that the resulting stresses will be safe. But by no means should the designer assume that they are safe。但是一個被損壞的軸承，會留下它為什么被損壞的線索。 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。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。相比之下，帶狀或冠狀保持架能較容易地使?jié)櫥瑒┑竭_(dá)全部表面。同樣，機床主軸只能容許最小的振擺，以保證切削精度。 軸承缺陷可以通過其頻率特性進(jìn)一步加以鑒定。通過加工制造它們可以分為許多的型號，分別用于許多的場合。它是齒輪逐漸進(jìn)行嚙合并平穩(wěn)的從一個齒到 另一個齒傳遞運動，那樣就使斜齒輪具有高速重載下平穩(wěn)傳遞運動的能力。與其相配的齒輪叫 做蝸輪，蝸輪不是真正的斜齒輪。 另外一個難題，發(fā)生在難于預(yù)示錐齒輪輪齒上的應(yīng)力，實際上是由于齒輪被加工成錐狀造成的。因此，如若軸要做得有足夠的剛度以致?lián)锨惶?，那么合?yīng)力符合安全要求那是完全可能的。因為幾何形狀的重要性是散熱表面。所傳遞的扭矩關(guān)系到作用力，摩擦系數(shù)和離合器或制動器的幾何狀況。 “軸”這個詞包含著多種含義，例如心軸和主軸。輪齒可以鑄出， 15 銑制或滾切加工。在交錯軸斜齒設(shè)計中，當(dāng)該齒的斜角相等時所產(chǎn)生滑移速度最小。 直齒圓柱齒輪輪齒的初始接觸處是跨過整個齒面而伸展開來的線。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。測量噪聲的單位為 anderon。保持架的尺寸誤差和軸承圈與滾珠的偏心都會引起 NRR。污染的特征是使軸承過早的出現(xiàn)磨損。 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。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。 that is ,a righthand driver goes with a righthand driven. In the design of crossedhelical gears, the minimum sliding velocity is obtained when the helix angle are equal. However, when the helix angle are not equal, the gear with the larger helix angle should be used as the driver if both gears have the same hand. 7 Worm gears are similar to crossed helical gears. The pinion or worm has a small number of teeth, usually one to four, and since they pletely wrap around the pitch cylinder they are called threads. Its mating gear is called a worm gear, which is not a true helical gear. A worm and worm gear are used to provide a high angularvelocity reduction between nonintersecting shafts which are usually at right angle. The worm gear is not a helical gear because its face is made concave to fit the curvature of the worm in order to provide line contact instead of point contact. However, a disadvantage of worm gearing is the high sliding velocities across the teeth, the same as with crossed helical gears. Worm gearing are either single or double enveloping. A singleenveloping gearing is one in which the gear wraps around or partially encloses the worm.. A gearing in which each element partially encloses the other is, of course, a doubleenveloping worm gearing. The important difference between the two is that area contact exists between the teeth of doubleenveloping gears while only line contact between those of singleenveloping gears. The worm and worm gear of a set have the same hand of helix as for crossed helical gears, but the helix angles are usually quite different. The helix angle on the worm is generally quite large, and that on the gear very small. Because of this, it is usual to specify the lead angle on the worm, which is the plement of the worm helix angle, and the helix angle on the gear。通過一些細(xì)致的偵察工作，我們可以采取行動來避免軸承的再次失效。這種破壞稱為低荷振蝕。 蠕動不象過早疲勞那樣普遍。 12 銹是濕氣污染的一種形式， 它的出現(xiàn)常常表明材料選擇不當(dāng)。因此在機 床的應(yīng)用中應(yīng)該使用非重復(fù)性振擺較小的軸承。通常軸承缺陷被分為低、中、 高三個波段。所以我們對齒輪和軸的了解和認(rèn)識必須是多層次多方位的。斜齒輪使軸的軸承承受徑向和軸向力。蝸桿和蝸輪通常是用于向垂直相交軸之間的傳動提供大的角速度減速比。 直齒錐齒輪易于設(shè)計且制造簡單，如果他們安裝的精密而確定，在運轉(zhuǎn)中會產(chǎn)生良好效果。但決不意味著設(shè)計者要保證；它們是安全的，軸幾乎總是要進(jìn)行計算的，知道它們是處在可以接受的允許的極限以內(nèi)。各種各樣的離合器和制動器可作如下分類： 2． 輪緣式內(nèi)膨脹制凍塊； 3． 輪緣式外接觸制動塊；