Internal Geneva Mechanism

AIM :

Design the Internal Geneva Mechanism

OBJECTIVE :

1. Create 3D models for driver and driven wheels.
2. Perform motion analysis by rotating the driver wheel at 10rpm for 1st study and 20 rpm for another study.
3. Obtain the Results for Contact force (between driving and the driven wheel) as a function of time, angular displacement of the driven wheel & then driver wheel's angular velocity with and without "Precise contact"

INTRODUCTION :

An internal Geneva drive represents a unique variation in design. In this configuration, the drive wheel's axis is supported on just one side.The angle through which the drive wheel must rotate to initiate a single step of the driven wheel is consistently less than 180° for an external Geneva drive, while it exceeds 180° for an internal one. This difference results in a longer switch time for the internal Geneva drive, prolonging the duration during which the driven wheel remains stationary.

THEORY :

The Geneva drive is a gear mechanism that translates a continuous rotation movement into intermittent rotary motion.The rotating drive wheel is usually equipped with a pin that reaches into a slot located in the other wheel (driven wheel) that advances it one step at a time. The drive wheel also has an elevated circular blocking disc that "locks" the rotating driven wheel in position between steps.

Types of Geneva drives are Follows:

1) External Geneva Drive
2) Internal Geneva Drive
3) Spherical Geneva Drive

Applications of Geneva Mechanism :

1) The common application of Geneva Drive is Movie Projectors.
2) Wrist Watches.
3) Plotters – Plotter is a computer printer for printing vector graphics.
4) Automated sampling machines.
5) Banknote Counting Machines.

PROCEDURE :

1. Create a 2D sketch for the Driven Wheel according to the provided dimensions.
2. Transform the 2D sketch into a 3D part model and save it as a part file.
3. Create a 2D sketch for the Drive Wheel of the internal Geneva drive based on the given dimensions.
4. Convert the 2D sketch into a 3D part model and save it as a part file.
5. Begin a new assembly part file.
6. Import both the part files for the Drive Wheel and the Driven Wheel of the internal Geneva drive.
7. Use mates to assemble the Drive Wheel with the Driven Wheel, ensuring they are properly aligned and at a specific center-to-center distance.
8. Save the assembled assembly file separately.
9. Open the assembly in a new window for motion analysis.
10. Set up a motion study, choose motion analysis, and configure the necessary parameters.
11. Add a motor to the center axis of the Drive Wheel, initially set at 10 RPM.
12. Implement solid contact surfaces for the mechanism, specifying the materials for the Drive Wheel and Driven Wheel.
13. Calculate the contact force between the Drive Wheel and Driven Wheel, display the results in plots.
14. Select angular displacement for the Driven Wheel and angular velocity for the Drive Wheel.
15. Set the frame count to 60 for the 10 RPM motor, and then to 120 frames for the 20 RPM motor, both with and without precision contact.
16. Click on the "Calculate" option and initiate the animation to obtain the final results.

Parts Created:

Motion Study Performed:

Final Results: