Creating a Creo 7 mechanism with non-standard gear teeth

[MZ_9727658]

I am using Creo Parametric 7.0 7.0.2.0

Hi, I have an assembly that is comprised of 3 parts. One part is fixed and the other two are gear like but have non-standard gear teeth. The parts with teeth do not rotate in the same plane like a spur gear and not at a 90 deg. right angle like a bevel gear. I've tried creating a mechanism using pin joints on the two moving parts, but the mechanism function doesn't allow me to define this as a gear mechanism. Also tried applying '3D contacts' to the surface of the teeth but apparently the surfaces on the teeth are not planer or cylindrical and are not selectable as such. Need help in defining a functional mechanism that will simulate the motion of the teeth as they rotate. We just need to view the meshing clearances as the parts move, not necessary for the parts to be motor driven (hand movement will suffice). As such, we need the meshing teeth surfaces to come in contact with each other. Any suggestions??

Here are the errors that I faced
none

[TomU]

Can you include a screenshot of the parts?

[MZ_9727658]

Hi Tom,

I would like send images but the design is proprietary, and I am not able to disclose the features that are related to this issue.  I was hoping someone might have encountered a similar issue with non-standard gear assemblies and either provide a work-around or let me know it can't be done in Creo.  Essentially, consider my design as a beveled gear arraignment that has the axis of one of the gears positioned at 120 degrees relative to the other.  It's only a partial gear, but we need to make sure the teeth mesh properly from tooth to tooth.  Also tried using 3D contacts on tooth surfaces to drive movement with no success.  Thanks for any insight you can provide. 

-Marv Z

[MZ_9727658]

Tom,

I searched the internet and found something similar that illustrates the gear mechanism within my assembly.  Here's the link to a YouTube video of it.  https://youtu.be/l3xxDxlsIdA

As you can see the gears in the video are curved (non-standard) and are aligned in a spherical arrangement. Is there a way to create a functional mechanism in Creo for this type of gear pair?  I'm guessing no, but maybe you might think of something that would work.

-Marv 

[TomU]

I don't think Creo can (easily) do what you want.

1.)  Cam surfaces cannot bow.

https://support.ptc.com/help/creo/creo_pma/r8.0/usascii/#page/simulate/mech_des/cams/surfaces_cams.html#wwID0EJVIM

2.)  Cam curves must be planner.  (Using the edges of the curved teeth won't work.)

https://support.ptc.com/help/creo/creo_pma/r8.0/usascii/#page/simulate/mech_des/cams/curves_cams.html#

3.)  3D Contact is limited on where it can be used.

https://support.ptc.com/help/creo/creo_pma/r8.0/usascii/#page/simulate/mech_des/3D_Contact/about_3d_contact.html#

Theoretically you might be able to create multiple curves through the gear teeth, offset them into the teeth some amount, place points along each of the curves, and then add 3D contacts on each of the points (with their diameters set to half of the curve offset value).  Essentially a gob of 3D contacts on each face.  Seems like a ton of work and I think it will quickly become so heavy that Creo won't be able to calculate the contact in any useful fashion.

Not sure if anyone else has any ideas...

[MZ_9727658]

Tom, thanks for the suggestion but yeah, that looks way too complicated for this particular application.

-Marv

[TomU · Accepted solution]

It's really too bad you can't just define contact at the body level.

[pausob]

Your description does not offer a clue as to why you can't define a gear pair between the two pin-joints.

Perhaps one of these tutorials will help you?

https://www.youtube.com/c/vpalffy/search?query=gear