4/19/19

1

Suril V. Shah

ME 222: Kinematics of Machines and Mechanisms

[L29] Cam Design 1

4/19/19 1IIT Jodhpur

Suril V. Shah

Types of follower motion

2

Rotating/Oscillating

Translating

4/19/19

2

Suril V. Shah

Forced and Formed closed

3

Suril V. Shah

Formed closed cam and follower

4

4/19/19

3

Suril V. Shah

Types of Follower

5

Suril V. Shah

Axial cam with form closed follower

6

4/19/19

4

Suril V. Shah

Some Cams and follower

7

Suril V. Shah

Type of motion constraintsCritical Extreme Position (CEP)Critical Path Motion (CPM)

8

4/19/19

5

Suril V. Shah

Type of Motion Program Rise-FallRise-Fall-DwellRise-Dwell-Fall-Dwell

9

Suril V. Shah

Follower function CAM profile

CAM Design

4/19/19 10IIT Jodhpur

4/19/19

6

Suril V. Shah

Cam timing diagram

11

Suril V. Shah

SVAJ DIAGRAMS

12

4/19/19

7

Suril V. Shah

Naive Cam Design—A Bad Cam.

13

Suril V. Shah

Naive Cam Design—A Bad Cam.

14

4/19/19

8

Suril V. Shah

The Fundamental Law of Cam DesignAny cam designed for operation at other than very low speeds must be designed with the following constraints:

The cam function must be continuous through the first and second derivatives of displacement across the entire interval (360 degrees).

Corollary:The jerk function must be finite across the entire interval (360 degrees).

15

Suril V. Shah

where h is the total rise, or lift, θ is the camshaft angle, and β is the total angle of the rise interval.

Simple Harmonic Motion (SHM)

16

4/19/19

9

Suril V. Shah

SVAJ DIAGRAMS

17

Suril V. Shah

non-quick-return RF case: rise in 180°and fall in 180°

4/19/19 18IIT Jodhpur

4/19/19

10

Suril V. Shah

Cycloidal displacement

19

Suril V. Shah

Cycloidal displacement

20

4/19/19

11

Suril V. Shah

Combined functionsDynamic force is proportional to acceleration. To minimize dynamic forces,

should minimize the magnitude of the acceleration keep it continuous.

Kinetic energy is proportional to velocity squared.

We also would like to minimize stored kinetic energy,

21

Suril V. Shah

Constant AccelerationFunction that minimize the peak value of the magnitude of the acceleration for a given area in a given interval

22

4/19/19

12

Suril V. Shah

Trapezoidal Acceleration

23

Suril V. Shah

Modified Trapezoidal Acceleration

24

4/19/19

13

Suril V. Shah

Modified Trapezoidal Acceleration

25

Suril V. Shah

Modified Trapezoidal Acceleration

26

4/19/19

14

Suril V. Shah

Modified Sinusoidal Acceleration

27

Suril V. Shah

Modified Sinusoidal Acceleration

28

4/19/19

15

Suril V. Shah4/19/19 29IIT Jodhpur

Thank youNext Class: Cam Design

4/19/19 IIT Jodhpur 30