Expansion of pinion and gear tooth in radial direction 1

[SMKRe]

The gear and pinion are running at high speeds and no-load condition.

are the pinion and gear tooth will have different expansions in radial direction?

I think, as the the gear is larger in size, the growth or expansion of the gear tooth is more than the pinion tooth.

if the expansion of the gear tooth is more, is there any contact between the gear tooth and pinion root area?

Please clarify.

 

[Tmoose]

"Please clarify."
ditto


"I think, as the the gear is larger in size, the growth or expansion of the gear tooth is more than the pinion tooth."
But the rpm of the pinion is faster in direct proportion to the diameters.
The relative thickness of the gear rim ( bore to dedendum/root circle) may enter into it.

"High rpm." ?
3" gear 3,000 rpm, or 15,000 rpm ?

 

[SMKRe]

Both the gear and pinion on solid gears.

Both are running at same pitch line velocity.

The Ansys results are showing the expansion of gear tooth is more than the pinion tooth.

is there any contact between the gear tooth and pinion root area?

Thanks

 

[mfgenggear]

Op
That depends, if designed correctly no there should not be contact in the root area.
Thermal expansion depends on the temperature and the type of material
And the thermal expansion rate of the
Material. The gear will have more expansion because it is larger.
The rate of expansion inch per inch.
If the gear major diameter and backlash are design correct there should be no issues.
A total composite and tooth to tooth
TCE, TTCE Will verify if there is interference, and if the gear teeth have been machined correctly.
Please advise AGMA grade new or old spec, or ISO grade.

 

[Tmoose]

"The Ansys results are showing the expansion of gear tooth is more than the pinion tooth."
How long is a rope?

And the radial expansion due to "centrifugal force" is .............
2µm, 10 mm, ????

"Please clarify."
You go first.

Describing technical results with adjectives like MORE, LESS, BETTER, WORSE does not provide much at all for even a kind hearted interested listener to go on.
Surely you had more than that when you defined the problem and built the FEA model?

https://www.sciencebuddies.org/scie.../engineering-design-compare-scientific-method

https://www.bobbydarin.net/linepanel.jpg

https://static.wikia.nocookie.net/gameshows/images/c/cb/WML_03.PNG/revision/latest?cb=20120406064507

 

[BrianPetersen]

Why do you care?

Properly designed gearboxes will have sufficient clearances between teeth, evident as backlash, for any such minor thermal or stress-related expansion to be accommodated without interference. If it ever gets to a binding condition with no backlash, you are going to have big trouble in a big hurry.

Design in the right amount of backlash (clearance) ... Done. No problem.

What am I missing?

 

[3DDave]

Another request to answer the generally unanswerable, mainly from incomplete questions.

What Ansys analysis? What are the gear materials? Is it a thermal expansion? We don't know. Yes, a nylon gear might expand more than a steel pinion even if it has lower centripetal acceleration. We don't know.

Will there be interference? What's the tooth profile? Is it shifted? Are the teeth tips chamfered? We don't know.

AGMA has many guides to designing gears to account for all sorts of factors. As I recall AGMA is one of the more reasonably priced sources of information for their area of expertise. (ASME - take the hint.)

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