Short Answer:

A follower displacement diagram is a graphical representation that shows how the displacement of a follower varies with the rotation of the cam. It helps to understand the motion pattern of the follower, such as rise, dwell, and return during one complete rotation of the cam.

This diagram is very useful for designing cam profiles, as it clearly indicates how the follower should move in each phase of the cam’s motion. The follower displacement diagram helps engineers to design cams that provide smooth and efficient motion without jerks or sudden acceleration.

Detailed Explanation :

Follower Displacement Diagram

A follower displacement diagram is an essential graphical tool used in the study of cam and follower mechanisms. It describes how the follower moves (displacement) as the cam rotates. The horizontal axis of the diagram represents the cam angle (rotation), and the vertical axis represents the displacement of the follower. The diagram helps in visualizing the follower’s motion during one full rotation of the cam and ensures that the designed motion is smooth and continuous.

1. Meaning of Follower Displacement Diagram

The follower displacement diagram shows the relationship between the angular movement of the cam and the linear or oscillating motion of the follower. Each point on the curve of the diagram corresponds to a specific cam angle and the follower’s corresponding position. The total cam rotation (360°) is divided into several sections depending on the follower’s motion: rise, dwell, and return.

• Rise (Outstroke): The part of the diagram where the follower moves away from the cam center or upward.
• Dwell: The portion of the diagram where the follower remains stationary while the cam continues to rotate.
• Return (Fall): The part where the follower moves back to its original position.

These sections are designed according to the desired motion of the mechanism.

2. Purpose of the Follower Displacement Diagram

The main purpose of drawing the follower displacement diagram is to design the cam profile correctly. By knowing how much and how fast the follower should move for a given cam rotation, engineers can shape the cam so that it produces the desired motion. The diagram ensures:

• Smooth motion without sudden shocks.
• Accurate follower displacement according to design requirements.
• Reduced wear and tear on mechanical parts.
• Better control over acceleration and velocity of the follower.

3. Construction of Follower Displacement Diagram

To draw a follower displacement diagram, follow these basic steps:

1. Draw a Base Line: Represent the base circle or zero displacement line horizontally.
2. Mark Cam Angles: Divide the horizontal axis (representing 360° cam rotation) into different angles showing rise, dwell, and return periods.
3. Plot Displacement Points: On the vertical axis, mark follower displacements according to the required motion (e.g., 0 mm to maximum lift).
4. Join the Points: Connect the plotted points smoothly according to the type of motion (uniform, harmonic, or uniform acceleration).

The resulting curve is the follower displacement diagram.

4. Types of Motion Represented in Displacement Diagram

Different types of follower motion can be represented using the follower displacement diagram. Each motion type affects the shape of the curve:

• Uniform Velocity Motion: The displacement graph is a straight line, showing constant follower velocity.
• Simple Harmonic Motion (SHM): The displacement curve follows a sine wave pattern, providing smooth acceleration and deceleration.
• Uniform Acceleration and Retardation Motion: The curve consists of parabolic shapes, representing constant acceleration during rise and constant retardation during fall.

These motion laws are chosen based on the performance required from the cam mechanism.

5. Applications of Follower Displacement Diagram

The follower displacement diagram is widely used in:

• Internal combustion engines, to control valve movements smoothly.
• Automation and textile machines, to coordinate complex follower motions.
• Machine tools, for timing operations accurately.
• Robotics and automatic machinery, to achieve precise repetitive motions.

In all these applications, the diagram ensures that the follower moves in the intended manner without vibration or mechanical stress.

6. Importance in Cam Design

The follower displacement diagram is the first step in cam profile design. Engineers use this diagram to calculate the required cam contour that will produce the desired motion. The smoothness of the cam operation depends on the accuracy of this diagram. Incorrect design may cause vibrations, noise, or even failure of the cam-follower system. Thus, careful preparation of the follower displacement diagram is critical for efficient machine operation.

Conclusion

In summary, the follower displacement diagram is a visual representation that describes how the follower moves during the cam’s rotation. It helps engineers design cam profiles that provide the desired motion pattern with minimal wear and maximum efficiency. By clearly defining the rise, dwell, and return periods, the diagram ensures smooth motion, controlled acceleration, and reliable performance of cam-follower mechanisms. Therefore, it is a fundamental tool in the field of machine design and mechanical engineering.