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MEEN 4110 – Mechanisms Design Fall - 2010 Lecture 09

MEEN 4110 – Mechanisms Design Fall - 2010 Lecture 09. CAM. Chapters Objectives. Up on completion of this chapter, the student will be able to Understand how to design a CAM-FOLLOWER Systems. Cam. Follower. Cam.

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MEEN 4110 – Mechanisms Design Fall - 2010 Lecture 09

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  1. MEEN 4110 – Mechanisms DesignFall - 2010Lecture 09 CAM

  2. Chapters Objectives • Up on completion of this chapter, the student will be able to • Understand how to design a CAM-FOLLOWER Systems.

  3. Cam Follower

  4. Cam • A cam is a rotating or sliding piece in a mechanical linkage used especially in transforming rotary motion into linear motion or vice versa. It is often a part of a rotating wheel (eg. an eccentric wheel) or shaft (eg a cylinder with an irregular shape) that strikes a lever at one or more points on its circular path. The cam can be a simple tooth, as is used to deliver pulses of power to a steam hammer, for example, or an eccentric disc or other shape that produces a smooth reciprocating (back and forth) motion in the follower which is a lever making contact with the cam. • The reason the cam acts as a lever is because the hole is not directly in the centre, therefore moving the cam rather than just spinning. On the other hand, some cams are made with a hole exactly in the centre and their sides act as cams to move the levers touching them to move up and down or to go back and forth.

  5. Design of Cam Systems The first stage in designing a cam system is the creation of a displacement diagram. A typical plate cam with an in-line roller follower is shown below with a displacement diagram. This figure shows the following characteristic features. • The rise- This is when the follower is moving away from the cam centre. The slope reflects the follower velocity. • The dwell- the is the period when the follower is stationary • The return - This is when the follower moves back towards the cam centre • The base circle on the cam is the smallest full diameter of the cam • The prime circle is centered on the cam rotation centre with radius at the follower roller centre when the follower is on the base circle • The cam profile is the shaped surface of the cam defining the follower motion

  6. Cam Design

  7. Types of Cams

  8. Types of Joint Closers (cam/follower joint)

  9. Follower Motion

  10. Types of Followers

  11. Obtaining the S Diagram

  12. Unwrapping/Linearizing a Cam

  13. Unwrapping/Linearizing a Cam

  14. The S Diagram

  15. Why S Diagram Cannot Have Negative Values New

  16. SVAJ Diagram

  17. SVAJ Diagram

  18. SVAJ Diagram

  19. Type of Motion Constraints

  20. Type of Motion Program • RF = rise-fall • RFD = rise-fall-dwell • RDFD = rise-dwell-fall-dwell

  21. Double-Dwell Cam Design- Choosing SVAJ Functions

  22. How Not Meet Cam Design Specifications (Linear Function)

  23. SVAJ Diagram

  24. SVAJ Diagram

  25. Cycloidal Motion

  26. Cycloidal Motion – SVAJ Diagram

  27. a Diagram

  28. v Diagram

  29. s Diagram

  30. Cycloidal Displacement Function

  31. Polynomial Function

  32. Polynomial Function

  33. Polynomial Function

  34. SVAJ Diagram

  35. Polynomial Function

  36. Polynomial Function

  37. Polynomial Function

  38. Polynomial Function

  39. Double Dwell Cam Design

  40. Double Dwell Cam Design

  41. Double Dwell Cam Design

  42. Double Dwell Cam Design

  43. Double Dwell Cam Design

  44. Single Dwell Cam Design

  45. Single Dwell Cam Design

  46. Single Dwell Cam Design

  47. Single Dwell Cam Design

  48. Single Dwell Cam Design

  49. Single Dwell Cam Design

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