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  1. 1. Dept. of Mechanical Engg. Presented By: Ajay Savita ME-A(5th SEM) Roll no: 0928ME121007
  2. 2. 3  Cams are used to convert rotary motion to oscillatory motion (almost always) or oscillatory motion to rotary motion (rarely)  For high speed applications – example, internal combustion engines  Objectives of this chapter: ◦ Learn fundamental concepts and terminology ◦ Learn how to design a cam and follower set to achieve a desired output motion.
  3. 3.  In IC engines to operate the inlet and exhaust valves
  4. 4. Based on modes of Input / Output motion 1 Rotating cam – Translating follower 2 Rotating cam – Oscillating follower 3 Translating cam – Translating follower
  5. 5. a) Radial or disc cam b) Cylindrical cam c) End cam
  6. 6. In radial cams, the follower reciprocates or oscillates in a direction perpendicular to the cam axis.
  7. 7. In cylindrical cams, the follower reciprocates or oscillates in a direction parallel to the cams axis.
  8. 8. It is also similar to cylindrical cams, but the follower makes contact at periphery of the cam as shown in fig
  9. 9.  Follower is the element to which the motion of cam is provided  i.e. Reciprocating or oscillating motion
  10. 10. Uniform Velocity The cam follower rises and falls at a constant speed. The start and stop of the follower is very abrupt and rough. Modified Uniform Velocity The modified uniform velocity motion smoothes out the roughness of the uniform velocity motion by adding a radius at the high and low points of the cam motion.
  11. 11. Harmonic Motion The follower motion has a smooth start and stop but the speed is not uniform. This type of motion is used where the cam rotates at a very fast speed. Uniform Acceleration The uniform acceleration is the smoothest motion of all of the cams and causes the follower to maintain a constant speed throughout the cam travel.
  12. 12. 1.According to the shape of follower  Knife edge follower  Roller follower  Flat faced follower  Spherical faced follower
  13. 13. a) Radial follower b) Offset follower
  14. 14.  When the motion of the follower is along an axis passing through the centre of the cam, it is known as radial followers. Above figures are examples of this type.
  15. 15. When the motion of the follower is along an axis away from the axis of the cam centre, it is called off-set follower. Above figures are examples of this type.
  16. 16.  1. Reciprocating or Translating  2.Oscillating or Rotating
  17. 17.  Cam profile: The outer surface of the disc cam.  Base circle : The circle with the shortest radius from the cam center to any part of the cam profile.  Trace point: It is a point on the follower, and its motion describes the movement of the follower. It is used to generate the pitch curve.
  18. 18.  Pitch curve : The path generated by the trace point as the follower is rotated about a stationery cam.  Prime circle: The smallest circle from the cam center through the pitch curve
  19. 19.  Pressure angle: The angle between the direction of the follower movement and the normal to the pitch curve.  Pitch point: Pitch point corresponds to the point of maximum pressure angle.
  20. 20.  Pitch circle: A circle drawn from the cam center and passes through the pitch point is called Pitch circle  Stroke: The greatest distance or angle through which the follower moves or rotates