Cams Cam Basics
Cams Cylindrical Cam Radial Cam Cam Principle A cam produces a simple means to obtain irregular or specified predictable designed motion. The simple operation of a cam has a rotating shaft with an irregularly shaped disc (Cam) attached. A follower with a small roller attached to it pushes against the cam. As the shaft rotates, the roller follows the irregular surface of the cam causing the follower to rise or fall according to the profile of the cam. There are two major kinds of cams, the radial ram and the cylindrical design. The radial arm design changes a rotary motion into either an up and down motion or a rocking action. The cylindrical design causes the follower to operate perpendicular to the cam shaft.
Cam Terms Cam Terms Working Circle The working circle is considered the distance equal to the distance from the center of the cam shaft to the highest point on the cam. Base Circle The base circle is a circle with a radius equal to the distance from the center of the shaft to the center of the follower wheel at its lowest position. Follower Displacement The follower displacement is the position of the follower from a specific zero or rest position in relation to time or distance measured in inches or degrees. Rotation The rotation of the cam is either clockwise or counter clockwise. Cam profile The cam profile is the actual working surface contour of the cam. .
Cam Terms Displacement Diagram The displacement diagram is a designed layout of the required motion of the cam. It is laid out on a grid with the length of the grid equal to one revolution of the cam. Dwell The dwell is a period of time during which the follower does not move. Time Interval The time interval is the time it takes the cam to move the follower to the designed height.
Cam Motion 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.
Cam Motion 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.
Cam Followers Cam Followers There are many types of followers. A few of the basic types of followers are: roller, pointed, flat face, and spherical face.