Analysis of a Rigid Eccentric CAM
In this analysis, all the components of the cam system are assumed to be rigid and the results are applicable to low-speed systems.
A circular disc cam with the cam shaft hole drilled off center is known as eccentric plate cam. The image shows a simplified reciprocating eccentric cam system consisting of a plate cam, a flat face follower and a retaining spring.
Mechanism Monday TheroryofMachines xDesign
Create CAM Disc
- Open Part Design App
- Edit the 3D Shape
- Go to Essentials section of the Action bar and select Positioned Sketch
- Create the following sketch.
- Go to Model section of the Action bar and select Pad
- Create a pad of 20 mm.
- Go to Essentials section of the Action bar and select Point and create a point at origin (0,0,0)
Create Follower
- Open Part Design App
- Edit the 3D Shape
- Go to Essentials section of the Action bar and select Positioned Sketch
- Create the following sketch.
- Go to Model section of the Action bar and select Pad
- Create a pad of 20 mm.
- Go to Essentials section of the Action bar and select Point and create a point:
- (0,0,60mm)
Create Frame
- Open Part Design App
- Edit the 3D Shape
- Go to Essentials section of the Action bar and select Positioned Sketch
- Create the following sketch.
- Go to Model section of the Action bar and select Pad
- Create a pad of 20 mm.
- Go to Essentials section of the Action bar and select Point and create two points:
- (0,0,220mm)
- (0,0,0)
Create Assembly
- Create a Physical Product
- Insert the Cam Disc, Follower & Frame, and orient them properly
- Go to Assembly section of the Action bar and select Engineering Connection
- Create Fix Engineering Connection to the frame
- Create a Revolute Engineering Connection between frame and the cam disc (Add a Controlled Hinge)
- Create a Prismatic Engineering Connection between follower and the frame
- Create a Spring Engineering Connection between frame and the follower.
- Set
Simulation and Analysis
- Open Mechanical Systems Design App
- Go to Mechanical Systems Design section of the Action bar select Contact Connection
- Create a Contact Connection between follower and cam disc
- Create a mechanism using Mechanism representation command
- Test the motion using Mechanism Player
- Open Mechanical Systems Experience App
- Note: It will ask to Create a Simulation Object, Click OK
- Go to Scenario section of the Action bar
- Create a Law Excitation
- Select the revolute command of the mechanism as Support
- Angle Formula: Angle = -(`Excitations\\Law Excitation.1\\Time`* 360deg/1sec)*(0.1*`Excitations\\Law Excitation.1\\Time` /1sec)
- Create Gravity Excitation
- Create Position, Speed and Acceleration probe for Point in the Cam Disc with respect to point at the origin of the frame
- Create a Measure probe between a point on the follower and a point on the frame.
- Create a Dynamics Scenario with
- Excitation:
- Law Excitation
- Gravity Excitation
- Probe:
- Position, Speed and Acceleration
- Measurement Between
- Parameters:
- Start Time = 0s
- End Time = 25s
- Step Time = 0.01s.
- Excitation:
- Select Compute and Generate Results
- Select View Scenario Results
- Select appropriate data and switch to Plot tab to view the graphs.
| Simulation | Plot |
|---|---|
As you can see after reaching certain speed, the follower starts to jump. There will be some impact between the cam and the follower, resulting in a rattling, clicking and noisy operations. This is usually known as jump.
This can be prevented by
- increasing the preload exerted by the spring or
- the spring stiffness
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