Retrofit fix for motor end shield resonance
Retrofit fix for motor end shield resonance
(OP)
I am now spamming two topics in a row.
I have a problem with end shield resonance vibration in an industrial motor. It 4000 HP 1500 rpm machine with newly modified bearing system.
I cannot change the excitation source which is however new anti-friction bearing(DGBB) in drive end. Bearings are not spring-preloaded because there is cylindrical roller in the other end. Motor is a little bit inclined because of the application so that is basically all axial load what comes from rotor mass.
I think there might be two options:
1. End shield needs to stiffened or loosened or the damping of the shield needs to be increased. In practice, what kind retrofit modifications have you done when facing this kind of issue?
2. Preloading DE bearing with the coupling (axially elastic lamellar coupling is used)... Anyone tried this?
All lessons learned stories and rules of thumbs are highly appreciated! :)
I have a problem with end shield resonance vibration in an industrial motor. It 4000 HP 1500 rpm machine with newly modified bearing system.
I cannot change the excitation source which is however new anti-friction bearing(DGBB) in drive end. Bearings are not spring-preloaded because there is cylindrical roller in the other end. Motor is a little bit inclined because of the application so that is basically all axial load what comes from rotor mass.
I think there might be two options:
1. End shield needs to stiffened or loosened or the damping of the shield needs to be increased. In practice, what kind retrofit modifications have you done when facing this kind of issue?
2. Preloading DE bearing with the coupling (axially elastic lamellar coupling is used)... Anyone tried this?
All lessons learned stories and rules of thumbs are highly appreciated! :)





RE: Retrofit fix for motor end shield resonance
There is also a material consisting of rubber and lead laminated together in several plies. Good resonance damper and looks better.
Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.
RE: Retrofit fix for motor end shield resonance
RE: Retrofit fix for motor end shield resonance
That rubber-lead laminate was used to reduce vibrations in a supercalander.
Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.
RE: Retrofit fix for motor end shield resonance
RE: Retrofit fix for motor end shield resonance
The calander was lower, though. More like your frequency.
Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.
RE: Retrofit fix for motor end shield resonance
1 - rigidly attaching mass
2 - attempt to stiffen
3 - create a tuned dynamic absorber
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(2B)+(2B)' ?
RE: Retrofit fix for motor end shield resonance
I had to delete most slides in the 3rd part (stress estimation) to get it small enough to upload. If anyone wants that part, let me know.
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(2B)+(2B)' ?
RE: Retrofit fix for motor end shield resonance
A few ways to test for resonance:
attempt temporary bracing... often by wedging wooden timber between machine and nearby support ... and check for vibration reduction.
Observe behavior during speed changes.
I'm curious why you say "about". The frequency changes... or is spread out among multiple peaks.. or you don't have a vib analyser ?
If you know the exact frequency and the bearing part number, it would be interesting to see how this frequency relates to the bearing fault frequencies such as outer race ball passing frequency.
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(2B)+(2B)' ?
RE: Retrofit fix for motor end shield resonance
I forgot to add that it is variable speed drive(0 to 1500 rpm). I dont have the vibration data now with me, to see exact resonance frequency. I am at home on a sick leave. But yes, it is one clear peak. It seems to correspond 2 x outer race bypass freq.
Resonance noise was first judged by bearing specialist who has been dealing a lot with similar motors. And he verified that it is "absolutely" bearing exciting the end shield.
RE: Retrofit fix for motor end shield resonance
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(2B)+(2B)' ?
RE: Retrofit fix for motor end shield resonance
For vfd I'm thinking damping devices like Gunnar's tar thing are the best option.
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(2B)+(2B)' ?
RE: Retrofit fix for motor end shield resonance
Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.