1. ME321 Kinematics and Dynamics of Machines
Steve Lambert
Mechanical Engineering,
U of Waterloo
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2. Cam Design
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3. Cam Types
Plate cam with translating roller follower
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4. Cam Types Translating or wedge cam with translating follower
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5. Cam Types
Cylindrical cam with translating roller follower
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6. Cam Types
Face cam with oscillating follower
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7. Translating Followers
(a) Flat-faced (b) Roller (c) Point
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8. Oscillating Followers
Flat-Faced Roller Spherical-Face
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9. Positive Return Follower
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10. Cam Design
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11. Cam Design
We specify cams in terms of the required motion of the follower:
critical path motion
critical extreme position
Want to specify follower displacement to provide continuous velocity and acceleration - finite jerk
Once follower displacement specified, choose follower geometry and design cam profile
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12. Critical Path Motion Draw displacement profile through required points
Difficult to ensure smooth operation
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13. Critical Extreme Position
Only critical points specified (eg., maximum lift)
Must specify actual displacement profile to provide continuous velocity and acceleration and finite jerk
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14. Constant Velocity Profile
Simple design and analysis
But, horrible dynamic performance
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15. Parabolic Displacement Profile
Constant Acceleration
Equations for first half of rise:
But, infinite jerk
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16. Cycloidal Motion
C is determined by setting the maximum displacement equal to L:
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17. Other Profiles
Modified Trapezoidal Profile:
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18. Cycloidal Profiles: Rise: C-1 + C-2 = C-5 Fall: C-3 + C-4 = C-6
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19. Harmonic Profiles
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