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Mechanisms Design MECN 4110

Mechanisms Design MECN 4110. Professor: Dr. Omar E. Meza Castillo omeza@bayamon.inter.edu http://facultad.bayamon.inter.edu/omeza Department of Mechanical Engineering Inter American University of Puerto Rico Bayamon Campus. Tentative Lectures Schedule.

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Mechanisms Design MECN 4110

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  1. Mechanisms Design MECN 4110 Professor: Dr. Omar E. Meza Castillo omeza@bayamon.inter.edu http://facultad.bayamon.inter.edu/omeza Department of Mechanical Engineering Inter American University of Puerto Rico Bayamon Campus

  2. Tentative Lectures Schedule

  3. One thing you learn in science is that there is no perfect answer, no perfect measure. A. O. Beckman Topic: CAMs Cam and Follower

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

  5. Cam Follower

  6. 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.

  7. 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. • Rise-This is when the follower is moving away from the cam centre. The slope reflects the follower velocity. • Dwell- the is the period when the follower is stationary • Return - This is when the follower moves back towards the cam centre • Base circle on the cam is the smallest full diameter of the cam • Prime circle is centered on the cam rotation centre with radius at the follower roller centre when the follower is on the base circle • Cam profile is the shaped surface of the cam defining the follower motion

  8. Cam Design

  9. Types of Cams

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

  11. Follower Motion

  12. Types of Followers

  13. Obtaining the S Diagram

  14. Unwrapping/Linearizing a Cam

  15. Unwrapping/Linearizing a Cam

  16. The S Diagram

  17. Why S Diagram Cannot Have Negative Values New

  18. SVAJ Diagram

  19. SVAJ Diagram

  20. SVAJ Diagram

  21. SVAJ Diagram

  22. SVAJ Diagram

  23. Type of Motion Constraints

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

  25. Double-Dwell Cam Design- Choosing SVAJ Functions

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

  27. SVAJ Diagram

  28. SVAJ Diagram

  29. Cycloidal Motion

  30. Cycloidal Motion – SVAJ Diagram

  31. a Diagram

  32. v Diagram

  33. s Diagram

  34. Cycloidal Displacement Function

  35. Polynomial Function

  36. Polynomial Function

  37. Polynomial Function

  38. SVAJ Diagram

  39. Polynomial Function

  40. Polynomial Function

  41. Polynomial Function

  42. Polynomial Function

  43. Double Dwell Cam Design

  44. Double Dwell Cam Design

  45. Double Dwell Cam Design

  46. Double Dwell Cam Design

  47. Double Dwell Cam Design

  48. Single Dwell Cam Design

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