機(jī)械類中英文翻譯.doc

英文原文camsvarious motions can be produced by the action of a cam against a follower.mamy timing devices are operated by can action.the purpose of andy cam is to produce a displacement of its follower;a secondary follower is often .used to produce additional displacement in another location.the most popular type is the plate cam.the cylindrical type is used to transmit linear motion to a follower as the cam rotates.three-dimensional cam are sometimes used;these provide some unusual follower motions,but also make follower design difficult.the camshaft in the automotive engine illustrates a simple but important application of a late cam.the cam assemblies in automatic record players illustrate a somewhat more complex application.cam profiles are accurately constructed by either praphical or mathematical methods.the transitiom from development drawings to working (shop) drawing can be made in several ways:1.make a full-scale template.this is desirable from the manufacturing standpoint,but it will not guarantee accurate cam profiles.2.use radial dimensions.this is fairly accurate,but sometimes produces layout problems in the shop.3.use coordinate dimensioning.this procedure will ensure accuracy.in selecring one of these methods,one should consider the function of the cam in terms of desired preciseness.because the cam work outline already determined, therefore the cam structural design mainly was determines the curve outline axial thickness and the cam and the drive shaft connection way. when the work load compares the hour, curve outline axial thickness generally takes for the outline curve biggest radius of vector 1,/10 /5; regarding a stress bigger important situation, must with carry on the design according to the cam contour surface from the contact intensity. when determination cam and drive shaft joint way, should synthesize the consideration cam the assembling and dismantling, the adjustment and firmly grades the question. regarding implementing agency more equipment, between its each execution component movement coordination usually determined by the cycle of motion chart, therefore in assembly cam gear time, the cam contour curve initial station (pushes regulation starts) the relative position to have according to the cycle of motion chart to carry on the adjustment, guarantees each execution component to be able according to the pre-set sequence synchronized action. therefore, requests the cam in the structural design to be able to be opposite to the drive shaft carries on the rotation along the circumference direction, and reliably performs fixedly. the simplest method uses the clamping screw nail fixed cam, or with clamping screw nail pre- fixed, after treats adjusts uses the pin to be fixed again.from structural design: from structure: when design must consider from the guidance and prevented revolves. from movement rule design: involves many aspects from the movement rule design the questions, besides consideration rigidity impact and flexible impact, but also should maximum speed vmax which has to each kind of movement rule, maximum acceleration amax and its the influence performs the comparison. 1) vmax bigger, then momentum mv is bigger. if from is suddenly prevented, the oversized momentum can cause the enormous impulse, endangers the equipment and the personal safety. therefore, when is bigger from the quality, in order to reduce the momentum, should choose the vmax value smaller movement rule. 2) amax bigger, is bigger. function in high vice- contact place stress bigger, the organization intensity and the wear resistant request is also higher. regarding high speed cam, in order to reduce the harm, should choose the amax value smaller movement rule. first states several kind of movements rules vmax, amax, the impact characteristic and the suitable situation following table regarding swings from the cam gear, its movement graph x-coordinate expression cam corner, y-coordinate then separately expresses from, angular speed and angle acceleration. this kind of movement graph has the state of motion and above is same.from structural design: from structure: when design must consider from the guidance and prevented revolves. from movement rule design: the cam gear design basic question 1. cam gears type choice, the definite cam shape, with from maintains the high vice- contact from the shape and the movement form and the cam the way 2. from the movement rule design, according to the application situation to from the travelling schedule and the state of motion request, determines from the movement rule. 3. cam gears basic parameter design, determines from the travelling schedule, various movements angle, the cam radius, , the roller radius, the center distance, from the length and so on. 4. cam contours curve design. 5. cam gears bearing capacity computation. 6. cam gears structural design, plan organization assembly drawing and various components shop drawingfromstructural design: from structure: when design must consider from the guidance and prevented revolves. from movement rule design: the cam gear design basic question 1. cam gears type choice, the definite cam shape, with from maintains the high vice- contact from the shape and the movement form and the cam the way 2. from the movement rule design, according to the application situation to fromthe travelling schedule and the movement 1, the cam gear application cam gear is includes the cam the high vice- organization, the cam gear has the structure to be simple, may accurately realize request merit and so on movement rule, thus obtains the widespread application in the industrial production, specially automatic device and in the automatic control device, obtains the widespread application. 2nd, the cam gear classification according to two moves the relative motion characteristic classification between the component (1) the plane cam gear 1) the disk cam; 2) translation cam. (2) space cam gear according to from movement vice- element shape classification (1) apex from; (2) roller from (3) flat base from. note: classifies this part of content when the introduction cam gear, should point out each kind of cam gear the good and bad points and its the adaption situation, showed each kind of cam gear the inner link, will build the foundation for the later translation cam and the column cam contour design.3rd, the throwout lever movement rule (1) the cam gear cycle of motion and the basic term terminology push the regulation movement angle: with from pushes the cam corner which the regulation corresponds; far stops the angle: with from far rests the cam corner which the regulation corresponds; return trip movement angle: with cam corner which corresponds from the return trip; nearly stops the angle: with from nearly rests the cam corner which the regulation corresponds; cam: take the cam axle center as the center of a circle, take its outline slightly to diameter r0 as the radius circle; from ravelling schedule: in pushes in the regulation or the return trip from the biggest displacement, indicated with h;: the cam center of rotation with from guides way the bias distance, indicated with e.types of camsplate cams are simple to fabricate.the follower can be moved in various patterns with various rise /fall ratios.motion should be controlled to avoid abrupt changes in force transmitted from the cam to the follower.one should carefully determine horizontal force components,since these present problems designing the follower assembly guide.critical reactions occur at points a and b.these reaction values must be computed.the relative vertical position of point a with respect to b needs to be raised if the reaction value at bis excessive.the position of b should be as close to cam as possible to minimize flexure in the roller-follower support.this type produces reciprocating motion in the follower.again,dorces need to be determined and dimensions chosen so as to avoid excessive component sizes.a tapered roller follower is frequently employed ;the groove in the periphery of the cam should be shaped to accommodate the follower.this type of cam is expensive to produce.the cylindrical cam has two outstanding features.one is the fact that the cam is positive actiong.n outside forces (such as gravity or spring action ) are needed to hold the follower against the working surface of the cam.the second feature is the fact that the follower can move through a complete cycle in the course of several revolutions of the cam.for example,it is possible to design the cam so the follower could move from a starting position at the left end to the extreme right position in three revolutions( or more),then the starting position in two revolutions.other variations are possible.a translation cam is illustrated.in the figure shown the cam reciprocates horizontally and the follower moves up and down.a pivoted follower can be used with this type .the translation cam can be made positive by providing a guided plate with an inclined slot for the cam;the slot cam then engage a pin or roller on a guided vertical reciprocated follower.with the latter type ,however,a complete force analysis is a critical phase of the design.in this type,the cam rotates and the follower (ususlly a roller or pin) is guided by a groove cut into the end face of a cylindrical section .rotation of the cam provides translation of the follower.this type is also positive acting.production costs for this type of cam are much higher than for a simple plate cam.a constant diameter cam is illustrated .this is merely a circular plate with the camshaft hole eccentrically located.the amount of eccentricity determines the amount of follower displacement.as the cam rotates,the follower reciprocates.this arrangement is sometimes known as a scotch yoke mechanism.follower action is positive ;harmonic motion is produced by this type of arrangement.types of followersin neneral,the follower is considered to be the part that comes in contact with the cam profile .however,when a seconday follower is used, the motion of the secondary follower is dictated by that of the primary follower.for example ,a roller follower can be reciprocated by acting against the edge of a pivoted follower.the simplest type of follower is the reciprocationg type that merely moves up and down (or in and out ) with the rotation of the cam;the centerline can be either collinear with the cam centerline or offset from it .contact with the cam can be via a point,a knife edge,a suface ,or a roller.a flat-afced reciprocating follower is shown if a point or surface is employed for contact the high normal force can result in abrasion and excessive wear.if the load being transmitted from the cam to the follower is small,the problem is not serious.for example ,the operation of a small snap-action switch does not produce cam surface wear.miniature snap-action electrical switches have actuators with various configurations;some of these are in the form of rounded points or thin meta sections.miniature three-way valves in air circuits have similar actuators.if cams are used to operate mechanical components directly,a roller is much more effective.cam rollers are commercially available in roller sizes ranging from1/2 in .to 6 in basic dynamic capacities range from 620 to 60000 ,based on 33.33 rpm and 500hr of minimum life .correction factors must be used for any other speed or life values.it should be noted that the cam can be lubricated through and oil hole in the end of the shank.rolling contact with the cam surface minimizes wear problems.several mounting arrangements are possible with this type of followr .shows the roller follower mounted on a pivoted arm .a pivoted flat-faced follower is shown .as with any flat-faced follower,friction between the follower face and the cam profile must be controlled.proper lubrication can reduce the effects of friction.漢語翻譯:凸輪 通過凸輪和從動件的作用，可得到不同的運(yùn)動。許多計時裝置由凸輪驅(qū)動。使用凸輪的目的是使其從動件產(chǎn)生位移，次級從動件常用來在另一位置產(chǎn)生附加位移。最常用的凸輪是盤形凸輪。圓柱凸輪用來將其旋轉(zhuǎn)運(yùn)動轉(zhuǎn)變?yōu)閺膭蛹闹本€運(yùn)動。最常用的凸輪是盤形凸輪。圓柱凸輪用來將其放置運(yùn)動轉(zhuǎn)變?yōu)閺膭蛹闹本€運(yùn)動。有時也用三維凸輪，它們提供一些不建黨的從動件運(yùn)動，也使從動件設(shè)計難度加大。汽車發(fā)動機(jī)上的凸輪軸顯示了盤形凸輪的簡單和重要的應(yīng)用場合，錄音機(jī)上的凸輪組件是更復(fù)雜的應(yīng)用實(shí)例。凸輪輪廓可用作圖法或數(shù)學(xué)計算法來精確設(shè)計，將設(shè)計圖轉(zhuǎn)換成加工圖可用下面幾種方法：1 制造一個實(shí)尺樣板。這是制造需要，但不能保證精確的凸輪輪廓。2 使用徑向尺寸設(shè)計。這相當(dāng)精確，但在生產(chǎn)時有時會產(chǎn)生排布問題。3 用座標(biāo)尺寸設(shè)計。這種方法能保證精度。選用這些方法時，應(yīng)按要求的精度考慮凸輪的作用。凸輪的結(jié)構(gòu)設(shè)計：因凸輪的工作輪廓已經(jīng)確定，所以凸輪的結(jié)構(gòu)設(shè)計主要是確定曲線輪廓的軸向厚度和凸輪與傳動軸的連接方式。當(dāng)工作載荷較小時，曲線輪廓的軸向厚度一般取為輪廓曲線最大矢徑的1/101/5；對于受力較大的重要場合，需按凸輪輪廓面與從動件間的接觸強(qiáng)度進(jìn)行設(shè)計。在確定凸輪與傳動軸的聯(lián)接方式時，應(yīng)綜合考慮凸輪的裝拆、調(diào)整和固定等問題。對于執(zhí)行機(jī)構(gòu)較多的設(shè)備，其各執(zhí)行構(gòu)件之間的運(yùn)動協(xié)調(diào)性通常由運(yùn)動循環(huán)圖確定，因此在裝配凸輪機(jī)構(gòu)時，凸輪輪廓曲線起始點(diǎn)（推程開始點(diǎn)）的相對位置需按運(yùn)動循環(huán)圖進(jìn)行調(diào)整，以保證各執(zhí)行構(gòu)件能按預(yù)定程序協(xié)調(diào)動作。為此，在結(jié)構(gòu)設(shè)計上要求凸輪能相對于傳動軸沿圓周方向進(jìn)行轉(zhuǎn)動，并可靠地加以固定。最簡便的方法是采用緊定螺釘固定凸輪，或用緊定螺釘預(yù)固定，待調(diào)整好后再用銷子固定。從動件的結(jié)構(gòu)設(shè)計：直動從動件的結(jié)構(gòu)：設(shè)計時要考慮從動件的導(dǎo)向和防止旋轉(zhuǎn)。從動件運(yùn)動規(guī)律的設(shè)計:從動件運(yùn)動規(guī)律的設(shè)計涉及許多方面的問題，除考慮剛性沖擊和柔性沖擊外，還應(yīng)對各種運(yùn)動規(guī)律所具有的最大速度vmax、最大加速度amax及其影響加以比較。1)vmax愈大，則動量mv愈大。若從動件突然被阻止，過大的動量會導(dǎo)致極大的沖擊力，危及設(shè)備和人身安全。因此，當(dāng)從動件質(zhì)量較大時，為了減小動量，應(yīng)選擇vmax值較小的運(yùn)動規(guī)律。2)amax愈大，慣性力愈大。作用在高副接觸處的應(yīng)力愈大，機(jī)構(gòu)的強(qiáng)度和耐磨性要求也就愈高。對于高速凸輪，為了減小慣性力的危害，應(yīng)選擇amax值較小的運(yùn)動規(guī)律。前述幾種運(yùn)動規(guī)律的vmax、amax、沖擊特性及適用場合如下表對于擺動從動件凸輪機(jī)構(gòu)，其運(yùn)動線圖的橫坐標(biāo)表示凸輪轉(zhuǎn)角，縱坐標(biāo)則分別表示從動件的角位移、角速度和角加速度。這類運(yùn)動線圖具有的運(yùn)動特性與上述相同。凸輪機(jī)構(gòu)設(shè)計的基本問題1. 凸輪機(jī)構(gòu)類型選擇，確定凸輪形狀、從動件形狀與運(yùn)動形式及凸輪與從動件維持高副接觸的方式2. 從動件運(yùn)動規(guī)律設(shè)計，根據(jù)應(yīng)用場合對從動件行程和運(yùn)動特性的要求，確定從動件運(yùn)動規(guī)律。3. 凸輪機(jī)構(gòu)基本參數(shù)設(shè)計，確定從動件行程、各運(yùn)動角、凸輪基圓半徑、偏距、滾子半徑、中心距、從動件長度等。4. 凸輪輪廓曲線設(shè)計。5. 凸輪機(jī)構(gòu)承載能力計算。6. 凸輪機(jī)構(gòu)結(jié)構(gòu)設(shè)計，繪制機(jī)構(gòu)裝配圖和各零件的工作圖。凸輪機(jī)構(gòu)的應(yīng)用凸輪機(jī)構(gòu)是含有凸輪的高副機(jī)構(gòu)，凸輪機(jī)構(gòu)具有結(jié)構(gòu)簡單，可以準(zhǔn)確實(shí)現(xiàn)要求的運(yùn)動規(guī)律等優(yōu)點(diǎn)，因而在工業(yè)生產(chǎn)中得到廣泛的應(yīng)用，特別是自動機(jī)械和自動控制裝置中，得到廣泛的應(yīng)用。凸輪機(jī)構(gòu)的分類按兩活動構(gòu)件間的相對運(yùn)動特性分類(1)平面凸輪機(jī)構(gòu)1)盤形凸輪；2)移動凸輪。 (2)空間凸輪機(jī)構(gòu)按從動件運(yùn)動副元素形狀分類(1)尖頂從動件；(2)滾子從動件；(3)平底從動件。注：在介紹凸輪機(jī)構(gòu)分類這部分內(nèi)容時，應(yīng)指出各種凸輪機(jī)構(gòu)的優(yōu)缺點(diǎn)及其適應(yīng)場合，說明各種