Using assembly component constraints in NX6 1

[huhtabob]

I want to couple 2 discs together and have them act like gears meshing with each other using NX6 assembly constraints.
For instance: I have one disc on a axle that is 16 inches in diameter. I have another disc that is 32 inches in diameter on another axle that its center line is 24 inches from the 16 inch disc center line. Can I constrain the 2 discs so that if I turn the 16 inch disc 1 revolution the 32 inch disc turns 1/2 revolution? If so how?

 

[JohnRBaker]

That behavior is typically what you would expect to see in a Motion application, for which Constraints were never intended to be. As the name implies, we are talking about 'positional constraints' and not 'kinematic relationships'.

That being said, you could try this. Once you have them positioned correctly relative to each other, Constrain the rotational position of both 'gears' using an Angle constraint. And then assign the angular position of the larger 'gear' to be an expression equal to the ratio of the teeth in the smaller gear divided by the teeth in the larger gear times the expression value used for the angle of the smaller 'gear', or in your example, the ratio of the circumferences of the circles (make sure that either the orientation of the angular references or the sign of the expression is such that the gears 'rotate' in opposite directions). Now to rotate the gears simply edit the angle of the smaller 'gear'.

Attached is a sample consisting of an Assembly of 2 gears arranged and constrained as I've described above. Also included is a GRIP program 'animate_assy.grx'. Open the Assembly and execute the program, entering the expression name 'Input-Angle' and then entering the start and end values of the expression as well selecting a speed factor from 1 to 10.

John R. Baker, P.E.
Product 'Evangelist'
Product Design Solutions
Siemens PLM Software Inc.
Industry Sector
Cypress, CA

http://www.siemens.com/plm

http://www.plmworld.org/museum/

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

 

[JohnRBaker]

For those of who would like to see that gears animated, but who does not have a GRIP license, the attached example is self-contained in that the animation cycle is built into the assembly, but you will need a Studio license to play it back. So if you do have a Studio license, open the assembly, and go to...

View -> Visualization -> Create Animation...

...and when the dialog comes up, select the 'Rotate_Gear' item in the list and select the 'Preview Animation' button and then use the 'VCR' controls to play the animation.

Have fun.

John R. Baker, P.E.
Product 'Evangelist'
Product Design Solutions
Siemens PLM Software Inc.
Industry Sector
Cypress, CA

http://www.siemens.com/plm

http://www.plmworld.org/museum/

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