1、英文原文 Cams Various 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
2、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 simpl
3、e 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
4、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 ens
5、ure 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 co
6、nnection 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. Whe
7、n 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 cyc
8、le 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 pre
10、- 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 p
15、revented 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 situat
16、ion 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 c
17、ontours curve design. 5. cam gears bearing capacity computation. 6. cam gears structural design, plan organization assembly drawing and various components shop drawing Fromstructural 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 m
19、ovement 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 an
20、d 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 move
21、ment 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,
22、 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
