NX 7.5 Assembly Sequencing û Using Motion 1

[GB74]

I am a longtime I-DEAS user now using NX 7.5. In I-DEAS, I was able to animate a constrained engine assembly (crankcase, crankshaft, rods and pistons) by adding an angular constraint to the crankshaft and using it as the driving dimension. I have been trying to animate an engine assembly in NX using assembly sequencing but I’m experiencing some difficulties.

I constrained the assembly so that I can use Assemblies -> Component Position -> Move Component… on the crankshaft and it is free to rotate, moving the other components along with it as you would expect. I go to Assemblies -> Sequence…, choose Insert -> Motion and select the crankshaft. I move the handles to the crankshaft center and choose the appropriate handle to move for the rotation. I set it to have 36 frames and type in 360° for the angle and hit enter. The crankshaft rotates but the connecting rods stay fixed in the same position as they also rotate 360° around with the crankshaft. The pistons stay in the cylinders and do not move. I don’t understand how the connecting rods can break away from the pistons if they are constrained to each other. Has anybody experienced something like this? Is there a solution?

I’d like to add that a co-worker was able to make this work in NX 7.0 before the upgrade to NX 7.5. Also, I know you can do things like this in Motion Simulation but I do not have a license for it.

Thanks

NX 7.5.4.4
Teamcenter 8 (8.3.3.3_n01.1)

 

[JohnRBaker]

If your model is properly constrained yet still has degrees-of-freedom (ability to move) for the things that you wish to drive, such as your crankshaft, it should work fine. Before going into Assembly Sequencing you can 'test' the motion of the various parts of the Assembly by going to...

Assemblies -> Component Position -> Move Component...

...and select the Component, in this case the 'crankshaft', that you wish to drive and attempt to move it manually using the 'Move Component' tools and then watch what happens. If everything is 'moving' as expected then Sequencing should behave the same way.

Note that IF you have sub-Assemblies which have their own constraints then you may have to override some of them at the top-level Assembly in order to get ALL of the parts to move as you want them to since constraints are only solved at the level of the WORK part. Note that there are many threads in this forum covering overriding Assembly constraints in sub-Assemblies.

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
Siemens PLM:
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To an Engineer, the glass is twice as big as it needs to be.

 

[GB74]

John,

I downloaded the Circular_Cam.zip file you posted from the thread below and played it. The assembly rotated but the cam-followers did not move up and down with the cam (see attached). If I exit the assembly sequence task environment and rotate the "ring-1" component, the cam-followers follow the cam as you would expect.

This is kind of what I was seeing in my original post. The crankshaft rotated but the components ignored the assembly constraints. Is there a setting in NX I need to change to make this work?

http://www.eng-tips.com/viewthread.cfm?qid=324805

Thanks

NX 7.5.4.4
Teamcenter 8 (8.3.3.3_n01.1)

 

[JohnRBaker]

While in the Sequencing task, open the 'Sequence Navigator' (in the Resource Bar), and select the Sequence item at the top. Now make sure the 'Details' panel at the bottom of the Navigator is open and check the last item in the list, 'Assembly Constraints'. Is it set to 'On'? If not, select it and it should switch to 'On'. Once it's set to 'On', now playback the Sequence.

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

 

[GB74]

They are set to 'On'. If I turn them off, only the ring-1 component rotates.

 

[JohnRBaker]

I just opened that same assembly in both NX 6.0, the version the model was originally created with, and NX 7.5, and the sequences still runs just fine in both versions. Here's a picture showing the Sequence Navigator settings so that you can verify that this is what you're seeing as well:

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

 

[GB74]

I have the same Sequence Navigator settings. Could there be a setting in customer defaults, preferences, etc., that would make it behave this way?

I really appreciate you taking time to help.

Thanks

 

[JohnRBaker]

Not that I'm aware of.

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

 

[GB74]

John,

I mocked up an engine assembly similar to what I am working on. Please download the attached and play the sequence to see if it plays the same for you. There is a movie that shows what I am experiencing. If you can figure this out, I'll buy you a cup of coffee.

 

[jpetach]

GB74

Using your parts I can replicate your result using 7.5.5.4

With 7.5.5.4 MP11 the assembly sequence and avi perform correctly (the constraint between the rod and the pin is used in the assembly sequence).

It seems that the issue was addressed some time at or before MP11.

HTH,

Joe

 

[GB74]

Hi Joe,

I reported this issue to GTAC and it looks like it is a problem with NX version 7.5.4.4 MP3 (Maintenance Pack 3). The support person I was in contact with tried it on the same version and got the same result. It looks like the problem is fixed in MP10 and that explains why you got it to work with 7.5.5.4 MP11.

Thank you for looking into it.

Gary