INTERNAL GENEVA MECHANISM MOTION STUDY USING SOLIDWORKS
AIM: Internal Geneva Mechanism Motion study analysis for different conditions (change in RPM as well as frames of results).
OBJECTIVES:
1) Create 3D models for driver and driven wheels using given data
2) Perform motion analysis by rotating the driver wheel at 10rpm
3) Obtain the following plots
(i) Contact force (between driving and the driven wheel) as a function of time
(ii) Angular Displacement of the driven wheel
4) Compare the contact forces with and without "Precise contact" for following two conditions:
(i) with 10 RPM & 60 frames/sec
(ii) with 20 RPM & 120 frames/sec
5) Export the results to Excel (in form of CSV file) and make the plots over there
6) Make a plot of the driver wheel's angular velocity for 20 RPM & 120 frames/sec.
GENEVA MECHANISM:
> The Geneva Mechanism is a gear mechanism that transmits a continuous rotational motion into intermitten rotary motion.
> The rotating driving wheel is usually equipped with a pin that reaches into a slot located in the other(driven) wheel that advances it by one step as a time. The main wheel also has an elevated circular blocking disk that locks the rotating driven wheel in position beetween steps.
> In this project I have analysed an Internal geneva mechanism as per the data given in following images:
> The Model drawings that I have created are as following:
MOTION STUDY:
> Motion studies are graphical simulations of motion for assembly models. You can incorporate visual properties such as lighting and camera perspective into a motion study.
> Motion studies do not change an assembly model or its properties. They simulate and animate the motion you prescribe for a model. You can use SOLIDWORKS mates to restrict the motion of components in an assembly when you model motion.
> Motion Analysis:
- Add motors to drive the motion of one or more parts of an assembly.
- Prescribe the positions of assembly components at various times using set key points. Animation uses interpolation to define the motion of assembly components between key points
- You can use Motion Analysis for accurately simulating and analyzing the effects of motion elements (including forces, springs, dampers, and friction ) on an assembly. Motion Analysis uses computationally strong kinematic solvers, and accounts for material properties as well as mass and inertia in the computations. You can also use Motion Analysis to plot simulation results for further analysis.
STEPS INVOLVED IN ANALYSIS:
1) First of all the 3D models are created and then assembled in solidworks by giving mates and obtained the constrained motion of driving & Driven wheels.
2) First motion study is performed for the 10 RPM speed of input wheel and without the "Precise Contact". The Plots for Contact forces and Angular velocities are Obtained as a function of time.
3) Second motion study is performed for 10 RPM with "Precise contact" and the frames value is set as 60 frames/sec. The Plots for Contact forces and Angular velocities are Obtained as a function of time.
4) Third motion study is performed for 20 RPM with "Precise contact" and the frames value is set as 120 frames/sec. The Plots for Contact forces and Angular velocities are Obtained as a function of time.
5) The Graph data obtained from the solidworks is exported to the excel as a CSV file. From there the actual Plots are obtained for each motion study.
PLOTS OBTAINED FROM FIRST MOTION STUDY:
> From the above graph I can Observe that initially the value of force is higher and that is because of the motor is experiencing large amount of thrust and also the inertia of the driven wheel cause the driving wheel more contact force. After first slot contact I can Observe that in other matings the driving wheel experiencing lower force.
PLOTS OBTAINED FROM SECOND MOTION STUDY:
NOTE: As we Increase the value of the frames per seconds the new frames having the results values are getting involved in the results. The results will becomes more and more accurate as we increase the value of frames.
> Comparing this plot with previous plot I can differentiate that the value of contact force in previous plot is not entertained because of the frame containing the higher values were excluded from the results data and in this study due to the higher number of frames that value is now included in this results. therefore the value of forces in this plot are higher than that of previouse plot. Also here I can clearly see the force occuring at each contacts of slot.
PLOTS OBTAINED FROM THIRD MOTION STUDY:
> From this plot I can see that the value of contact force is increasing in the manner as the frame size increases. In addition of that the rpm also doubled, therefore the contact force is increasing at very higher rate.
THE GRAPHS OBTAINED FROM SOLIDWORKS WERE EXPORTED IN THE EXCEL FILE AS A CSV FILE AND THEN THE PLOTS ARE OBTAINED FROM EXCEL.