Continue to Site

Welcome to 3DCADForums

Join our CAD community forums where over 25,000 users interact to solve day to day problems and share ideas. We encourage you to visit, invite you to participate and look forward to your input and opinions. Acrobat 3D, AutoCAD, Catia, Inventor, IronCAD, Creo, Pro/ENGINEER, Solid Edge, SolidWorks, and others.

Catia Kinematics problem - Mechanism Simulation

MechEngFta

New member
Hello,
I am new to this forum and beginner in Catia. I have a problem and I need your valuable help! I designed a gripping mechanism, and I am in the process of creating the joints in order to simulate its motion, but for some reason it doesn't work the way I want it to. I am attaching a pic with the design so far
catia_help.jpg.
I hope it does get uploaded...So, I have made rigid joints between parts 5, 6, 7, 8, 9, 10 and the screw. (I am only describing one side, the other side is mirrored obviously...)And I have added a cylindrical joint between the screw and part 1(I want it to move only linearly though). Part 1 and rod 11 have a rigid joint as well, and so do part 2 and rod 12. Then I created a revolute joint between 11 and 2, and between 12 and 3. So far so good. It moves perfectly. Then, I wanted to make a revolute joint between 3 and 9 but it wont let me go on with the simulation any more. It says "The created command has no effect on the degree of freedom of the mechanism". The motion I want it to perform is this. As part 1 goes linearly up and down, part 15 closes and opens. rod 9 is fixed and part 3 revolves around it. Do you have any idea how I can fix that?
Thanks in advance!
 
Sorry for the delay. I don't have access to the Kinematics workbench to verify this for you. I hope you have this working by now. But if not, my comments below are based on the picture you attached.

a. To simplify the mechanism, I suggest ignoring (hide) all the pins (8, 9, 11, 12, 13 & 14). Just add a revolute joint between the holes in each set of linked parts. Once you get this working, you can add the pins later as rigid to their mating part.

b. I agree with you that parts 5, 6, 7, 8, 9 & 10 are all rigid to each other. Are these parts also fixed (do not move)?

c. The screw is not rigid to parts 5, 6, 7, 8, 9 & 10. The screw has to rotate about parts 6 & 7 and 1.

d. The screw must be engaged with a threaded hole, but I'm not sure if the threaded hole is in part 1 or parts 6 & 7. Could you please clarify this. Whichever part does not contain the threaded hole must have a clearance hole.

e. I'm surprised you were able to validate the screw portion of the mechanism (you said "it moves perfectly"). How were you able to get part 1 to move up and down without having a screw joint? Which part is fixed and which part/joint is the input command?

f. The picture shows several joints on the left-side. I would delete those until you get the right-side working.

g. After you added the revolute joint to part 3, I would suggest adding the other revolute joints to parts 3 & 15, 15 & 4 and 4 & 5 to "close the loop" and then try the simulation.
 
Last edited:

Articles From 3DCAD World

Sponsor

Back
Top