Last week 4/14/2010 I posted the following question:
I am trying to simulate a flexible conveyor belt with attachment lugs on the outside of the belt traveling around a pulley.
Has anyone come up with a technique in mechanism to show the movement of a belt traveling around a pulley ?
I searched and found information for showing a chain and sprocket in mechanism, this was not to difficult to do "bicycle chain links traveling around a sprocket", but I can't figure out how to simulate a totally flexible belt.
PTC tech support replied back to me with: "You will not be able to model the belt with the flexibility required, as Pro/ENGINEER creates only rigid models and doesn’t allow for deformation."
This was not an acceptable answer for me since I need to have a somewhat realistic simulation motion of a flexible belt to design the rest of my design around.
So here is the solution I came up with:
How to accurately show a flexible belt in motion using Pro/Mechanism
1. Create a simple model just basic curve to depict the pulleys / Gears and the belt travel.
2. Create a solid model of the lug profile that travels on the outside of the belt.
a. Add to this model a point at the center of the hole and the side datum plane
b. Also add a datum point at the vertex of the end point of the hole and the side datum plane.
3. Duplicate the solid model of the lug profile and just create datum curves that represent the shape of the lug.
a. To this model add datum points at the center of the lug and offset from the center at a distance of (lug pitch distance / 😎
b. also create a datum axis at the center of the lug
4. Create a assembly
5. Assemble the part curve that depicts the pulleys / Gears and the belt travel at the default location.
6. Assemble the solid model of the lug profile that travels on the outside of the belt, as a mechanism,
a. Planar “side datum plane to side datum plane”
b. Slot “Point at center of lug axis & datum curve that depicts the travel of the lug moving around the belt
c. Slot “point at vertex of lug dia.
7. Assemble the datum curve shape that represents the lug profile, as a mechanism,
a. Planar “side datum plane to side datum plane”
b. Bearing “the point (lug pitch distance / 😎 and the axis of the solid model of the lug.
c. Slot “point at the center of the datum curve lug and the datum curves that depicts the travel of the lug moving around the belt
8. Hide the solid model of the lug
9. Repeat assembly of the datum curve shape 7 x
a. This can be done by simply selecting the 1<sup>st</sup> instance & Selecting EDIT / REPEAT
b. Select the 2 “Point On Line” constraints and repeat until you have assembled 8 total instances in the model tree
10. Lastly assemble the solid model of the lug profile
a. Assemble by coordinate system to the last datum curve model.
11. Un-hide all models
12. Drag components around the curve.
Seems like a lot of steps but it really wasn't too hard !
I have attached a Zip file with the models and word document of the instructions.
Thanks to all those who replied back to my original post and if you have a need to do this now or in the future post back to this thread and I will be happy to assist you in anyway I can.
Regards
Dave McClinton
Sr. Mechanical Designer / MCAD Systems Administrator
McKesson Automation
724 741 7760
david.mcclinton@mckesson.com
