Internal Geneva Mechanism

AIM :- 

• Create 3D models for driver and driven wheels.
• Perform motion analysis by rotating the driver wheel at 10rpm.
• Obtain the following plots
  • Contact force (between driving and the driven wheel) as a function of time.
  • Angular Displacement of the driven wheel.
• Compare the contact forces with and without "Precise contact"
  • Show image for precise contact selection
  • Export the results that you get to Excel and make the plots over there.

THEORY:

The Geneva drive is also commonly called a Maltese cross mechanism. The Geneva mechanism translates a continuous rotation into an intermittent rotary motion. The rotating drive wheel has a pin that reaches into a slot of the driven wheel. The drive wheel also has a raised circular blocking disc that locks the driven wheel in position between steps.

There are three basic types of Geneva motion mechanisms namely external, internal and spherical. The spherical Geneva mechanism is very rarely used. In the simplest form, the driven wheel has four slots and hence for each rotation of the drive wheel it advances by one step of 90°. If the driven wheel has n slots, it advances by 360°/n per full rotation of the drive wheel.

In an internal Geneva drive the axis of the drive wheel of the internal drive is supported on only one side. The angle by which the drive wheel has to rotate to effect one step rotation of the driven wheel is always smaller than 180° in an external Geneva drive and is always greater than 180° in an internal one. The external form is the more common, as it can be built smaller and can withstand higher mechanical stresses.

Because the driven wheel always under full control of the driver, impact is a problem. It can be reduced by designing the pin in such a way that the pin picks up the driven member as slowly as possible. Both the Geneva mechanisms can be used for light and heavy duty applications. Generally, they are used in assembly machines.

 RESULTS:- 

The Graph where plot for different RPM

FOR 10 RPM:

Contact Force between the wheels @ 10 rpm:

Contact Force with precision of 60 frames per second@ 10 rpm:-

Angular velocity of the driven wheel@ 10 rpm:-

Angular velocity with precision of 60 fpm @10 rpm:-

Angular Displacement of the driven wheel @10 rpm :-

Angular Displacement of the driven wheel @10 rpm with same precision:-

FOR 20 RPM:-

Contact Force between the wheels @20rpm:-

Contact Force between the wheels @20rpm with precision of 120 fpm:

Angular velocity of the driven wheel @20rpm:-

Angular velocity of the driven wheel @20rpm with the precision of 120 fpm:

Angular displacement of the driven wheel @20 rpm:

Angular displacement of the driven wheel @20 rpm with same precision:

 The material selected for both the wheels, before running the motion analysis, is dry steel.