Internal Geneva Mechanism Using Solidworks

Objective:

To Create 3D model for driver and driven wheel of Internal Geneva Mechanism and perform motion analysis by rotating the driver wheel at 10rpm and 20rpm and compare the contact force as a function of time between driven and driver wheel at 10rpm and 20rpm with and without precise contact. And also to study the angular displacement of driver and driven wheel.

About Geneva Mechanism:

The Geneva Mechanism is a linkage that supplies a discontinuous (intermittent) rotary motion, and it is commonly used in both high and low-rotating speed machines. Generally, it consists of two important members the crank with a pin (driver member) and the slotted plate or wheel (driven member).The crank member provides an intermittent rotation to the follower member and keeps it from spinning between the stages of meeting. The two members should be designed so that the driving pin enters or leaves the slots tangentially. The driver member typically rotates at a constant angular velocity and when it rotates one revolution, the geneva mechanism rotates through a small portion of a revolution. This portion of revolution is dependent on the number of slots or stations.

Application and Use's of Geneva Mechanism

• Indexing tables in assembly lines,
• Tool changers for CNC machines,
• Mechanical watches etc...

Procedure:

Multibody Dynamics is used to find the Motion Analysis of driver and driven wheel of Internal Geneva Mechanism

Driver Wheel

Driving wheel is the wheel that transmits force or torque into the driven wheel and causing the rotation. A motor is connected to driver wheel and motor delivers enough torque to the driving wheel to rotate the driven wheel.

Driven Wheel

Driven wheel is the wheel from which output rotation is extracted. The driven wheel is rotated by driving wheel.

Assembly of Driver and Driven wheel

• Creating 3D model of driver and driven wheel.
• Assembling the 3D model of driver and driven wheel by use of constraints.
• Using Multibody Dynamics to find the Motion Analysis driver and driven wheel.
• In driver wheel motor is fixed to rotate at the constant speed of 10rpm and then increased to 20rpm.
• Fixing the contact type as Solid bodies of driver and driven wheel and assigning material as STEEL, and calculating the motion analysis for 14sec.

Output:

• Comparing the Contact Forces with and without Precise contact and Using 60 Frames per second for 10 rpm and then 120 Frames per second for 20 Rpm
• Angular Displacement of the driver and driven wheel.

Contact force at 10rpm without Precise contact.

Angular displacement of Driver wheel at 10rpm.

Angular displacement of Driven wheel at 10rpm.

Contact force at 10rpm with Precise contact.

Precise Angular displacement of Driver wheel at 10rpm.

Precise Angular displacement of Driven wheel at 10rpm.

Contact force at 20rpm without Precise contact.

Angular displacement of Driver wheel at 20rpm.

Angular displacement of Driven wheel at 20rpm.

Contact force at 20rpm with Precise contact.

Precise Angular displacement of Driver wheel at 20rpm.

Precise Angular displacement of Driven wheel at 20rpm.

Image of precise contact selection.

Result:

• Precise Contact gives has higher contact force and accurate results comparing with non-precise contact force.
• As we increase the motor rpm of the driver wheel contact force also get increased.
• When it comes to angular displacement of driven, when the driver tries to enter into the slot of the driven wheel, the contact force and angular displacement gets suddenly increases due to jerk which is easily visible in the graph.