LECTURE NOTES ENT348 MECHANICAL SYSTEM DESIGN Lecture 6 25/3/2015 CAM DESIGN

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1 LECTURE NOTES ENT348 MECHANICAL SYSTEM DESIGN Lecture 6 25/3/2015 CAM DESIGN Dr. HAFTIRMAN MECHANICAL ENGINEEERING PROGRAM SCHOOL OF MECHATRONIC ENGINEERING UniMAP COPYRIGHT RESERVED 2015 ENT348 Mechanical System 1

2 Study Week 6-7 Course Content Cam-follower systems Cam terminology, SVAJ diagrams, Fundamental law of cam design, Simple Harmonic motion, Cycloidal displacement or sine constant acceleration, Critical extreme position (CEP, and critical path motion (CPM). Delivery Mode Lecture Levels of Complexity Asses sment (7 hours) ENT348 Mechanical System 2

3 CO2: Ability to evaluate machinery dynamics of a mechanical system. ENT348 Mechanical System 3

4 OUTLINE Introduction Cam Terminology SVAJ diagrams Double-dwell cam design Single-Dwell Cam design Critical Path Motion Sizing The Cam-Pressure Angle and Radius of Curvature Practical Design Considerations ENT348 Mechanical System 4

5 Introduction A cam is a common mechanism element that drives a matting component known as follower. The camshaft is driven by the engine. As the cam rotates, and the rocker arm in turn, imparts a linear, reciprocating motion to a valve stem. The rocker arm follower needs to maintain contact with the cam surface to achieve the desired motion. ENT348 Mechanical System 5

6 ENT348 Mechanical System 6

7 CAM TERMINOLOGY Types of Cams 1. Plate or disk cam This type of cam is formed on a disk or plate. The radial distance from the center of the disk is varied throughout the circumference of the cam. Allowing a follower to ride on this outer edge gives the follower a radial motion. ENT348 Mechanical System 7

8 CAM TERMINOLOGY Types of Cams 2. A cylindrical or drum This type of cam is formed on a cylinder. A groove is cut into the cylinder, which varies along the axis of rotation. Attaching a follower that rides in the groove gives the follower motion along the axis of rotation. ENT348 Mechanical System 8

9 Types of Cams 3. A linear cam CAM TERMINOLOGY This type of cam is formed on a translated block. A groove is cut into the block with a distance that varies from the plane of translation. Attaching a follower that rides in the groove gives the follower motion perpendicular to the plate of translation. ENT348 Mechanical System 9

10 CAM TERMINOLOGY Classification of Cam-follower 1. Type of follower motion (translating or rotating). 2. Type of cam, radial, cylindrical, threedimensional. 3. Type of joint closure (force or form closed). 4. Type of follower (curved or flat and rolling or sliding). 5. Type of constraints (critical extreme position (CEP). ENT348 Mechanical System 10

11 Type of follower motion System with an oscillating or rotating follower Radial Cam AN OSCILLATING CAM-FOLLOWER ENT348 Mechanical System 11

12 CAM TERMINOLOGY Radial Cam A TRANSLATING CAM-FOLLOWER The choice between these two forms of the cam-follower is usually dictated by the type of output desired. ENT348 Mechanical System 12

13 Follower Position ENT348 Mechanical System 13

14 Type of joint closure Force closure requires an external force be applied to the joint in order to keep the two links, cam and follower, physical in contact. The force is usually provided by a spring. This force defined as positive in a direction that close the joint, cannot be allowed to become negative. The links have lost contact because a forceclosed joint can only push, not pull. ENT348 Mechanical System 14

Radial Cam Form closure No external force is required. There are really two cam surfaces in this arrangement, one surface on each side of the follower.

15 Radial Cam Form closure No external force is required. There are really two cam surfaces in this arrangement, one surface on each side of the follower. Each surface pushes, in its turn, to drive the follower in both directions. Figure shows track or groove cams that capture a single follower in the groove and both push and pull on the follower. ENT348 Mechanical System 15

16 Conjugate cams Radial Cam Figure shows conjugate terms. Two roller followers, attached to a common arm, are each pushed in opposite directions by the conjugate cams. ENT348 Mechanical System 16

17 Type of follower Radial Cam Part of the follower link that contacts the cam ENT348 Mechanical System 17

18 An axial cam An axial cam whose follower moves parallel to the axis of cam rotation. A face cam if open (face-closed) and a cylindrical or barrel cam if grooved or ribbed (form-closed) ENT348 Mechanical System 18

19 An axial cam ENT348 Mechanical System 19

20 Part loader ENT348 Mechanical System 20

21 ENT348 Mechanical System Part-handling machine 21

22 ENT348 Mechanical System 22

23 GRAPHICAL DISK CAM PROFILE DESIGN ENT348 Mechanical System Design Sem /2015 Mechanical Engineering Program School of 23

24 ENT348 Mechanical System Design Sem /2015 Mechanical Engineering Program School of 24

25 ENT348 Mechanical System Design Sem /2015 Mechanical Engineering Program School of 25

26 ENT348 Mechanical System Design Sem /2015 Mechanical Engineering Program School of 26

27 ENT348 Mechanical System Design Sem /2015 Mechanical Engineering Program School of 27

28 ENT348 Mechanical System Design Sem /2015 Mechanical Engineering Program School of 28

29 IN-LINE KNIFE-EDGE FOLLOWER ENT348 Mechanical System Design Sem /2015 Mechanical Engineering Program School of 29

30 IN-LINE ROLLER FOLLOWER ENT348 Mechanical System Design Sem /2015 Mechanical Engineering Program School of 30

31 IN-LINE ROLLER FOLLOWER ENT348 Mechanical System Design Sem /2015 Mechanical Engineering Program School of 31

32 ENT348 Mechanical System Design Sem /2015 Mechanical Engineering Program School of 32

33 TRANSLATING FLAT-FACED FOLLOWER ENT348 Mechanical System Design Sem /2015 Mechanical Engineering Program School of 33

34 ENT348 Mechanical System Design Sem /2015 Mechanical Engineering Program School of 34

35 PIVOTED ROLLER FOLLOWER ENT348 Mechanical System Design Sem /2015 Mechanical Engineering Program School of 35

36 PRESSURE ANGLE ENT348 Mechanical System Design Sem /2015 Mechanical Engineering Program School of 36

37 GRAPHICAL CYLINDRICAL CAM PROFILE DESIGN ENT348 Mechanical System Design Sem /2015 Mechanical Engineering Program School of 37

38 ENT348 Mechanical System Design Sem /2015 Mechanical Engineering Program School of 38

39 MACHINING A CAM ENT348 Mechanical System Design Sem /2015 Mechanical Engineering Program School of 39

40 ACTUAL CAM PERFORMANCE COMPARED TO THEORETICAL PERFORMANCE ENT348 Mechanical System Design Sem /2015 Mechanical Engineering Program School of 40

41 ENT348 Mechanical System Design Sem /2015 Mechanical Engineering Program School of 41

42 ENT348 Mechanical System Design Sem /2015 Mechanical Engineering Program School of 42

43 GENEVA MECHANISM ENT348 Mechanical System Design Sem /2015 Mechanical Engineering Program School of 43

44 ENT348 Mechanical System Design Sem /2015 Mechanical Engineering Program School of 44

45 THANK YOU ENT348 Mechanical System 45

12/25/2015. Chapter 20. Cams. Mohammad Suliman Abuhiba, Ph.D., PE

12/25/2015. Chapter 20. Cams. Mohammad Suliman Abuhiba, Ph.D., PE Chapter 20 Cams 1 2 Introduction A cam: a rotating machine element which gives reciprocating or oscillating motion to another element (follower) Cam & follower have a line constitute a higher pair. of