THOERY OF MECHANISMS AND MACHINES Module-10 CAMS Instructed by: Dr. Anupam Saxena Associate Professor Department of Mechanical Engineering Indian Institute of Technology Kanpur anupams@iitk.ac.in FB 361 Prepared by: Abhishek Attal & Abhishek Sharma Final Year Dual Degree Student Department of Mechanical Engineering Indian Institute of Technology Kanpur attalab@iitk.ac.in, abhishr@iitk.ac.in NL312, FB369

M08- Recap Gears Terminology Gear Trains Simple Compound Epicyclic 12 Oct 2015 ME352A

Cam and Follower What are they? Why are they used? A higher pair joint, with one driver and one follower Why are they used? To transmit complex coordinated periodic motions Which one would be the driver? Cam! Which one would be driven? Follower! 12 Oct 2015 ME352A

Classification of Followers Radial Translating Follower Offset Translating Follower Oscillating Follower Nature of contact surface According to type of motion Knife Edge Follower Flat Face Follower Roller Follower Spherical Face Follower 12 Oct 2015 ME352A

Classification of Cams Disk/Radial Cam Wedge & Plate Cam Cylindrical Cam What would they look like? Observe! Most of the followers you’ve seen will need a spring to maintain contact. But those who don’t need a spring are called positive acting cams. Can you think of an example? 12 Oct 2015 ME352A

Radial Cam Nomenclature Traces motion of the follower Smallest circle that can be drawn tangential to the pitch curve Corresponding to point of maximum pressure angle, also decides the pitch circle Angle between direction of follower movement & normal to the pitch curve at any point Curve generated by trace point when we fix the cam (with reference to the cam) Smallest circle that can be drawn tangential to the cam profile 12 Oct 2015 ME352A

Displacement Diagram (Introduction & Terminologies) When follower moves away from cam centre When follower moves towards cam centre Maximum velocity pitch point When follower is as calm as Buddha! Minimum velocity pitch point It plots follower displacement against cam rotation 12 Oct 2015 ME352A

Displacement Diagram (Introduction & Terminologies) q y y q x 12 Oct 2015 ME352A

Displacement Diagram (Introduction & Terminologies) q y y x 12 Oct 2015 ME352A

How to Design a Cam 12 Oct 2015 ME352A Desired Motion Displacement Diagram Cam Type & Features Cam Profile 12 Oct 2015 ME352A

Constructing Displacement Diagram -Uniform Motion Sharp edges, infinite acceleration! NO! Uniform motion! Uniform velocity! Straight line graph! 12 Oct 2015 ME352A

Constructing Displacement Diagram -SHM L=5cm ϴ=0 ϴ=130 12 Oct 2015 ME352A

Constructing Displacement Diagram -Parabolic (y = aϴ2) & Polynomials L = 6cm ϴ = 80 12 Oct 2015 ME352A

Hungry for MORE? Go ahead and watch this Dude: [Seems like he got some money from Bentley to teach kinematics using MicroStation- an engineering software platform developed by the mammoth itself.] https://www.youtube.com/watch?v=8JtcEjaqc4Y&list=PLB059985630300733 12 Oct 2015 ME352A