1、6.附录：6.1 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.Th
2、e 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
3、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
4、 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
5、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 c
6、onnection 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. Wh
7、en 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 cy
8、cle 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
9、 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 pr
10、e- 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 impac
11、t 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
12、 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 r
13、esistant 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
14、 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 pr
15、evented 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 situati
16、on 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 co
17、ntours 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:
18、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 mov
19、ement 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
20、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 moveme
21、nt 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, w
22、ill 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 sto
23、ps 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
24、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 Ca
25、msPlate 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 probl
26、ems 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
27、 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 b
28、e 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.
29、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 m
30、ore),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 provid
31、ing 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) i
32、s 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 c
33、ircular 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
34、 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 b
35、e 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
36、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 seri
37、ous.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 si
38、milar 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 fac
39、tors 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 foll
40、ower 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.6.2 汉语翻译:凸轮 通过凸轮和从动件的作用，可得到不同的运动。许多计时装置由凸轮驱动。使用凸轮的目的是使其从动件产生位移，次级从动件常
41、用来在另一位置产生附加位移。最常用的凸轮是盘形凸轮。圆柱凸轮用来将其旋转运动转变为从动件的直线运动。最常用的凸轮是盘形凸轮。圆柱凸轮用来将其放置运动转变为从动件的直线运动。有时也用三维凸轮，它们提供一些不建党的从动件运动，也使从动件设计难度加大。汽车发动机上的凸轮轴显示了盘形凸轮的简单和重要的应用场合，录音机上的凸轮组件是更复杂的应用实例。凸轮轮廓可用作图法或数学计算法来精确设计，将设计图转换成加工图可用下面几种方法：1 制造一个实尺样板。这是制造需要，但不能保证精确的凸轮轮廓。2 使用径向尺寸设计。这相当精确，但在生产时有时会产生排布问题。3 用座标尺寸设计。这种方法能保证精度。选用这些方法
42、时，应按要求的精度考虑凸轮的作用。凸轮的结构设计：因凸轮的工作轮廓已经确定，所以凸轮的结构设计主要是确定曲线轮廓的轴向厚度和凸轮与传动轴的连接方式。当工作载荷较小时，曲线轮廓的轴向厚度一般取为轮廓曲线最大矢径的1/101/5；对于受力较大的重要场合，需按凸轮轮廓面与从动件间的接触强度进行设计。在确定凸轮与传动轴的联接方式时，应综合考虑凸轮的装拆、调整和固定等问题。对于执行机构较多的设备，其各执行构件之间的运动协调性通常由运动循环图确定，因此在装配凸轮机构时，凸轮轮廓曲线起始点（推程开始点）的相对位置需按运动循环图进行调整，以保证各执行构件能按预定程序协调动作。为此，在结构设计上要求凸轮能相对于
43、传动轴沿圆周方向进行转动，并可靠地加以固定。最简便的方法是采用紧定螺钉固定凸轮，或用紧定螺钉预固定，待调整好后再用销子固定。从动件的结构设计：直动从动件的结构：设计时要考虑从动件的导向和防止旋转。从动件运动规律的设计:从动件运动规律的设计涉及许多方面的问题，除考虑刚性冲击和柔性冲击外，还应对各种运动规律所具有的最大速度vmax、最大加速度amax及其影响加以比较。1)vmax愈大，则动量mv愈大。若从动件突然被阻止，过大的动量会导致极大的冲击力，危及设备和人身安全。因此，当从动件质量较大时，为了减小动量，应选择vmax值较小的运动规律。2)amax愈大，惯性力愈大。作用在高副接触处的应力愈大，
44、机构的强度和耐磨性要求也就愈高。对于高速凸轮，为了减小惯性力的危害，应选择amax值较小的运动规律。前述几种运动规律的vmax、amax、冲击特性及适用场合如下表对于摆动从动件凸轮机构，其运动线图的横坐标表示凸轮转角，纵坐标则分别表示从动件的角位移、角速度和角加速度。这类运动线图具有的运动特性与上述相同。凸轮机构设计的基本问题1. 凸轮机构类型选择，确定凸轮形状、从动件形状与运动形式及凸轮与从动件维持高副接触的方式2. 从动件运动规律设计，根据应用场合对从动件行程和运动特性的要求，确定从动件运动规律。3. 凸轮机构基本参数设计，确定从动件行程、各运动角、凸轮基圆半径、偏距、滚子半径、中心距、从
45、动件长度等。4. 凸轮轮廓曲线设计。5. 凸轮机构承载能力计算。6. 凸轮机构结构设计，绘制机构装配图和各零件的工作图。凸轮机构的应用凸轮机构是含有凸轮的高副机构，凸轮机构具有结构简单，可以准确实现要求的运动规律等优点，因而在工业生产中得到广泛的应用，特别是自动机械和自动控制装置中，得到广泛的应用。凸轮机构的分类按两活动构件间的相对运动特性分类(1)平面凸轮机构1)盘形凸轮；2)移动凸轮。 (2)空间凸轮机构按从动件运动副元素形状分类(1)尖顶从动件；(2)滚子从动件；(3)平底从动件。注：在介绍凸轮机构分类这部分内容时，应指出各种凸轮机构的优缺点及其适应场合，说明各种凸轮机构的内在联系，为以
46、后的移动凸轮及圆柱凸轮轮廓的设计打下基础。推杆的运动规律（1）凸轮机构的运动循环及基本名词术语推程运动角：与从动件推程相对应的凸轮转角；远休止角 ： 与从动件远休程相对应的凸轮转角；回程运动角：与从动件回程相对应的凸轮转角；近休止角 ： 与从动件近休程相对应的凸轮转角；凸轮基圆 ： 以凸轮轴心为圆心,以其轮廓最小向径 r0 为半径的圆； 从动件行程: 在推程或回程中从动件的最大位移,用 h 表示；偏 距 : 凸轮回转中心与从动件导路间的偏置距离,用 e 表示。凸轮的类型有以下几种：盘形凸轮设计简单，制造容易。切向盘形凸轮，常用来适时开关阀门。从动件可按不同升降比实现不同形式的运动，应控制运动以
47、避免凸轮传到从动件的力发生突变。设计者应仔细分析从动件受力的水平力分量，因为它们会使从动件的导向出现问题。极限情况出现在A、B点必须计算这两点的作用力值。如果B点的值超量，点A相对于B的垂直位置就要升同。B点应量靠近凸轮，以减少滚子从动件支承弯曲。圆柱凸轮，它使从动件产生往复运动。需用分析受力，选择尺寸，以避免零件尺寸过大。圆柱凸轮经常使用锥形滚了从动件，并将凸轮表面上的槽适当加工以容纳从动件。这种凸轮制造成本高。圆柱凸轮有两个突出特点：一个特点是：凸轮与从动件为几何锁合，不需要外力（如重力或弹簧力）将从动件贴紧凸轮工作面；第二个特点是：可在凸轮转几转中，从动件完成一个完整循环。比如，可设计这
48、样的凸轮，当凸轮转3转（或更多转）时，从动件从左端起始点运动到右端极限位置，然后凸轮再转2转使从动件回到起点。当然，还可能有其他设计。凸轮水平往复运动，从动作一下运动。摆动从动件也可用于这种形式。通过带有斜槽的导板，可使移动凸轮与从动件实现几何锁合，斜槽与作垂直往复运动的从动件上的销或滚子配合。然而，在后一种型式中，完整的力的分析是设计的一个关键阶段。在这种形式中，凸轮旋转，从动件实现（通常是滚子或销）通过凸轮端面上的槽来引导。凸轮旋转使从动件移动。这种类型 的机构也是几何锁合，它的制造费用比简单的盘形凸轮高很多。等径凸轮，这只是一个带有偏心凸轮轴孔的圆盘，偏心量的大小决定了从动件位移的大小，
49、当凸轮旋转时，从动件作往复运动。这种装置有时称为苏格半约克机构。从动件运动时与凸轮为几何锁合。可通过这种装置得到谐和的运动。从动件的类型总的说来，从动件是与凸轮轮廓相接触的零件。然而，当用次数从动件时，次级从动件的运动就需通过主要从动件来实现。比如，滚子从动件可紧靠着摆动从动伯的边缘作往复运动。最简单的从动件是随着凸轮的转动而仅作上下（或进出）往复运动的从动件，其中心线可与凸轮中心线共线，也可与之偏离。它可通过点、刃口、表面或滚子与凸轮接触。如果用点或表面接触，很高的正应力会导致擦伤和过量的磨损。如果凸轮传到从动件的力不大，问题就不大严重。比如，操纵一个小的速动开关不会产生凸轮表面磨损。微型速动电开关有多种形式的启动器，有一些是圆点，有一些薄金属片。气动回路中的微型三通阀中有类似的启动器。如果凸轮用来直接驱动机械组件，滚子就非常有效。这就是一个往复运
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