Internal Geneva Mechanism
AIM: MOTION ANALYSIS OF INTERNAL GENEVA MECHANISM
OBJECTIVES:
- Motion analysis by rotating driving wheel at 10 RPM with & without precise contact.
- Motion analysis by rotating driving wheel at 20 RPM with & without precise contact.
- Obtain plot of contact force Vs time.
- Study the motion analysis.
BODY OF CONTENT:
- Geneva mechanism consists of two parts, one is driver wheel (input) & another is driven wheel (output).
- It is used to convert continuous motion of the driver wheel to the intermittent motion of the driven wheel.
Application:
- Indexing table of assembly line
- Tool changer of CNC machine
- Mechanical watches
- Film projectors
- Automobile industries
Design Steps:
- Make the CAD Model of the driver & driven wheel from the draft.
Driver Wheel:
Driven Wheel:
- Now do the assembly of driver & driven wheel.
- For motion analysis add the option from the Solidworks add in.
- Select motion analysis.
- Assign rotary motor to the driven wheel. Give 10 RPM as a value.
- Here we consider 60 Frame per second for 10 RPM & 120 Frame per second for 20 RPM.
- Now, we consider two cases
(1) With Precise motion
(2) Without Precise motion
Case: 01
With precise motion
- 10 RPM With 60 FPS:
To enable precise motion go to motion option & mark the option as shown below.
As discussed we considered 60 FPS here.
Now apply driven wheel & driver wheel as a contact body.
Calculate & run motion analysis for 20 second.
Now plot the graph of contact force Vs time.
We can see the peak value of reaction force is nearly 4250 N at regular interval of time.
- 20 RPM With 120 FPS
Now duplicate the same study.
Change the motor RPM to 20 & assign FPS to 120 as shown below.
Now run the analysis.
Now plot the graph of contact force Vs time.
We can see the peak value of reaction force is nearly 8600 N at regular interval of time.
Case: 02
Without precise motion
- 10 RPM With 60 FPS
Now disable precise motion option.
As discussed we considered 60 FPS here.
Now apply driven wheel & driver wheel as a contact body.
Calculate & run motion analysis for 20 second.
Now plot the graph of contact force Vs time.
We can see the peak value of reaction force is nearly 518980 N between interval of 12-14 sec.
- 20 RPM With 120 FPS
Now duplicate the same study.
Change the motor RPM to 20 & assign FPS to 120 as shown below.
Now run the analysis.
Now plot the graph of contact force Vs time.
We can see the peak value of reaction force is nearly 824620 N between interval of 8-10 sec.
CONCLUSION:
From the above plots we can conclude that the value of contact force is very high in case-02. This high values indicates high value of jerk which can be seen in imprecise motion. While in case-01 particular same value increases at regular interval of time. As I select precise option, time required for the study increases & hence the accuracy. Solver takes more time to solve the motion in case-01. Hence, the values obtain in case -01 are more precise.
Motion at 10 Rpm:
https://drive.google.com/file/d/1FhRmYrZQGcrnkzizI5I7rqG6Vs01NgmY/view?usp=sharing
Motion at 20 Rpm:
https://drive.google.com/file/d/1jgLDTX1ryh9ZJrvNTlLGR4De9f699NZT/view?usp=sharing