Internal Geneva Mechanism

OBJECTIVE: -

• To create a 3D model of driver and driven wheel of internal Geneva Mechanism
• Create assembly of the model
• Simulate the model at 10 RPM and 20 RPM
• Plot a graph of Contact Force between driver and driven wheel as a function of time
• Plot the graph of angular displacement of the driven wheel

THEORY: -

The Geneva drive or the Maltese cross 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, the driven wheel, that advances it by one step at a time. The main wheel also has an elevated circular blocking disc that locks the rotating driven wheel in position between steps.

Geneva drive application includes the pen change mechanism in plotters, automated sampling devices, banknote counting machines, and much other indexable equipments used in manufacturing such as – tool changer in CNC machines, the turrets of turret lathes, screw machines etc.

CAD MODEL ASSEMBLY: -

fig 1: Dimensions of Geneva Wheel Assembly

fig 2: Dimensions of Driver Wheel

RESULT AND DISCUSSION: -

fig 3: Contact force at 10 RPM

fig 4: Precise contact setting at 10 RPM

fig 5: Contact Force at 10 RPM with precise contact

fig 6: Angular Displacement at 10 RPM of Driven wheel

fig 7: Angular Displacement at 10 RPM of Driven wheel with precise contact

fig 8: Angular Velocity of Driven Wheel at 10 RPM

fig 8: Angular Velocity of Driven Wheel at 10 RPM with precise contact

fig 9: Contact force at 20 RPM

fig 10: Contact force at 20 RPM with precise contact

fig 11: Angular Displacement at 20 RPM of Driven wheel

fig 12: Angular Displacement at 20 RPM of Driven wheel with precise contact

fig 13: Angular Velocity of Driven Wheel at 20 RPM

fig 14: Angular Velocity of Driven Wheel at 20 RPM with precise contact

ANIMATION:-

https://youtu.be/3eDcLP2NO9o

CONCLUSION: -

• The average contact force increases with the angular rotation.
• Precise contact gives analytically correct results by using the equation s that represent the solid bodies.
• The velocity of the driven wheel increases and then decreases and then stops. This pattern repeats itself.
• At first, the angular acceleration takes place and then the retardation of the driven wheel takes place.
• At the start, the forces are high because of the initial jerk at the start