Internal Geneva Mechanism

Aim:

To create a 3D model of an internal geneva mechanism from the dimensions given. Perform motion study using SolidWorks using the given input parameters and find the contact forces in system and the angular displacment of the driver wheel.

Objective:

1. Model the driver in SolidWoeks
2. Model the driven wheel in Solid Works
3. Assemble the mechanism with calculated center to center distance.
4. Perform motion analysis on the assembled mechanism
5. Extract important parameters like angular displacment and contact force.

Theory:

Geneva mechansm or Malatese cross is gear mechanism that translates continuous rotation into intermittent rotory movment. The mechanism consists of a driving and a driven wheel. The driving wheel is equipped with a pin that generally slides into a slot in the driven wheel.

Applications:

• Production industries for mass production
• film projectors
• mechanical watches
• indexing tables and tool changers

Models:

Internal Geneva driver:

Driven wheel:

The following models were made based on the dimensions given.

Assembly:

Motion Analysis:

The motion analysis is done to find out contact forces with and without "precise contact".

Analysis parameters

1. Speed: 10 rpm
2. Frames per sec: 60 fps
3. Contact : Solid bodies - Precise contact

Precise contact selection screenshot:

Contact force(precise contact):

Contact force(without precise contact):

Angular displacment of Driven wheel:

Analysis parameters

1. Speed: 20 rpm
2. Frames per sec: 120 fps
3. Contact : Solid bodies - Precise contact

Contact force (precise contact):

Contact force (without precise contact):

Angular displacment of driven wheel

Plot for drivers angular velocity:

1. 10 rpm and 60fps

The above plot shows that the angular velocity of the wheel is constant at 60 deg/sec

2. 20rpm 120fps

the above plot shows that the angular velocity is constant at 120 deg/sec

Conclusion:

The internal geneva mechanism was modeled and assembled. the motion analysis for the system was also performed based on given specifications and contact forces along with angular displacment of driven wheel were plotted.