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Dave Reynolds

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Posts: 53
Reply with quote  #16 
If you are looking for a potential resource, I am in Nebraska and could help/mentor if you are interested
Dave
midlandsrc@cox.net
hidenseeky

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Posts: 5
Reply with quote  #17 
Crah(s),

Thanks again for all of the great feedback I have received. It has been a blessing to know that there are human resources available to me. Acting on the sage advice and wisdom of the senior posters, I have decided to incorporate what I can into my overall plan of self-realization/actuation/flagellation.

Tomorrow I head out on a route, two ethanol plants and a rubber manufacturing plant. I have not been able to get any extra time allocated from work, so I hope I can get everything done in 3 days. I am going to re-collect all the nameplate data I can, and try to get with the maintenance staff to confirm models, and hopefully score any electronic documentation they have (excel spreadsheets would be amazing). 

One of the harder things I am trying to understand is gearboxes. I have quite a few on my routes (driving agitators on fermentation tanks, driving rollers in the rubber mixing facility) and I'm a little lost on collection methodology, displacement vs. velocity, and identification. I don't know where to collect data from on the axial of an intermediate shaft for example, and I worry that I am taking horizontal and vertical measurements inconsistently. I have attached a drawing to outline what I mean. Sometimes there is a shaft cap or ring and I can collect off of that, but often it seems like I'm guessing, especially since I don't know for sure the gear configuration. I have a request in to get some diagrams but it seems like the asking is reflecting badly on me, since I should either trust the database (I don't) or I should already know (I don't!).

Gearbox Example.jpg 

In any case, thanks to all for your continuing help and support. 

In gratitude,

Technician No. 24601


__________________
Nothing Is Constant
Shurafa2

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Posts: 170
Reply with quote  #18 
For the database, I suggest taking photos if it is allowed.

They would help you in a variety of ways especially at the beginning of your specialty and as a newcomer to these facilities. Take photos for the nameplates, equipment layout, defects, access issues or other interesting findings. This photo collection is your memory instrument to recall what you see at site X. They could also help reporting.

Find a way to confirm the speeds in your first site visit if this is practical.

Regards- you- Ali M. Al-Shurafa

trapper

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Posts: 77
Reply with quote  #19 
Welcome to the forum. You're enthusiasm is palpable. Sounds like your situation is going to grind on that a little but don't give up.

Quote:
Originally Posted by hidenseeky
Crah(s),
One of the harder things I am trying to understand is gearboxes. I have quite a few on my routes (driving agitators on fermentation tanks, driving rollers in the rubber mixing facility) and I'm a little lost on collection methodology, displacement vs. velocity, and identification. I don't know where to collect data from on the axial of an intermediate shaft for example, and I worry that I am taking horizontal and vertical measurements inconsistently. I have attached a drawing to outline what I mean. Sometimes there is a shaft cap or ring and I can collect off of that, but often it seems like I'm guessing, especially since I don't know for sure the gear configuration. I have a request in to get some diagrams but it seems like the asking is reflecting badly on me, since I should either trust the database (I don't) or I should already know (I don't!).


I work with rubber machinery also so maybe I can help you along there. What type of mixers are you dealing with? We have all Banbury mixers here which output to mills -- either dual-roll type or sheeters which incorporate both a dual-screw and dual-roll. Either way, they all output sheet compound which is further worked into components with extruders or calenders, etc.

All use gearboxes to get the speed down to <100 RPM to work the rubber without tearing or separating it. It's important to remember that the roll mills typically have the rolls turning at slightly different speeds to knead the rubber as the sheet stock is formed. At this low a frequency, don't be tempted to switch to displacement (mils) for your spectrums. The resultant "ski slope" at the bottom of the range from the double integration will usually hide any details you possibly may find in the 1-3x turning speed range. At those RPMs, the waveform with about 7-12 revolutions and/or enveloping of some type will be more useful for detecting problems. The spectrum may be helpful with things such as gear mesh or bearing fault harmonics. I use a 100mV/g accelerometer. I'd personally prefer the 500mV/g. I don't use it for several reasons although if I needed to do some specific troubleshooting, I may call it in for duty.

As to where to take the readings on the gearboxes, see if you can collect some pictures. I'll see if I can get some together in the near future although the beginning and end of the month are pretty busy for me so it may take a bit.

Lastly, don't give up on asking for information on any of your equipment -- especially for gearboxes. I finally got the drawings, parts list and tooth counts for one of my mills just a couple months before confirming the gearbox was eating itself. However, if you have to "guesstimate", there's some great information here:

https://www.machineryanalysis.org/post/gearbox-intermediate-shaft-figuring-out-the-geartooth-numbers-7942251?highlight=gearbox+tooth+count&pid=1290997643

https://www.machineryanalysis.org/post/need-help-with-gearbox-specs-9746282?highlight=gearbox+tooth+count&pid=1304374733

https://www.machineryanalysis.org/post/gear-tooth-count-9994036?highlight=gearbox+tooth+count&pid=1307077223


Danny Harvey

Sr. Member / Moderator / Supporter
Registered:
Posts: 1,402
Reply with quote  #20 
We have covered a rubber/plastic facility with three calendar lines.  All have great big gearboxes and operate at varying speeds. It took about 15 years to get all the bearing and geartooth data for every single drive. I got it by scraping nameplates, digging through drawings and records, contact manufacturers, opening gearboxes and counting teeth, inspecting bearings that we made blind calls on, and inspecting one that we missed (also blind). I got some of it by googling once that became a tool so it is a little easier now. Google the nameplate and you can at least look at the pictures and figure out what's inside and where.

Some of the gearbox manufacturers are very forthcoming with their information, while others do not give it out at all.

Banbury Mixers can be tricky like Trapper said. There will be an extra set of gears either in the gearbox or on the mixer itself. That's so that the mixer shafts will be counter rotating at different speeds.  The mixer will also make a big clunk.

Make sure that you get the data under load and at least know the input and output speeds.  The gearmesh frequencies and other shaft speeds might be found in the velocity spectra with some examination. The mixers we cover are manually loaded and make batches as opposed to a continuous mixing process. Hopefully, your data acquisition time will match the batch time and you'l be able to get through in one batch.

Things like Feed Mills, Drop Mills, Strainers and some extruders often have big open gearing that is old and worn from years of misalignment and poor lubrication. They make a whole lot of noise but keep on turning. On all of our mills on all three Calendar lines that is at 2560 cpm from the 25 tooth mill pinion turning at 102.4 rpm. We did have a case where the drop mill gears were effecting the product and leaving an impression after the calendar about 100 feet away.


As far as mounting, the most direct path to the bearing in the radial position is where I go.  On what you are showing (a parallel shaft reducer), that's usually vertical.  I also get an axial directly over the bearing diameter as close to the load zone as possible. I usually collect a velocity spectrum and acceleration twf plus a demod or PeakVue in both the radial and axial directions. Look at the overalls and start with the highest ones. 

If it's a Calendaring process, then the gearboxes go from big on the mills, to huge on the Calendar or Pinion Stand. And they might have multiple drive trains in one housing. If they are variable speed it gets trickier. The big one has 4 double reduction drive trains with slightly different input and output speeds.  
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