Cams and Motion
Definition
Cam
A mechanical part that converts rotational motion into linear motion.
How Cams Work
- Cam Profile: The shape of the cam determines the motion it imparts.
- Follower: A component that rides on the cam's surface, translating its shape into motion.
- Camshaft: The rotating axis on which the cam is mounted.
- Crank: In some systems, cams work alongside a crank, which converts rotary motion into reciprocating motion.
Types of Cams and Their Motion
Pear Cam
- Shape: Resembles a pear, with a rounded end and a tapered section.
- Motion: Provides a smooth rise and fall with a dwell period (no movement).
- Uses: Automated machinery where a pause in motion is needed, such as textile machines.
In a sewing machine, a pear cam controls the needle's movement, allowing it to pause at the top and bottom of each stitch.
Circular Cam
- Shape: Perfect circle.
- Motion: Produces a constant, uniform motion.
- Uses: Simple applications where consistent motion is required, like rotary pumps.
Circular cams are sometimes called eccentric cams when the rotation axis is offset from the center.
Triangular Cam
- Shape: Triangular, with rounded corners.
- Motion: Creates a sudden rise and fall, with sharp transitions.
- Uses: High-speed machinery where quick, repetitive actions are needed, such as printing presses.
- When analysing a cam, pay attention to the transition points.
- These are critical for understanding how the cam will impact the follower's motion.
