recently , we get a new service for balancing a mollases blender .

The shaft its weight 1000 kg with paddles like below picture.

Type balacing: 2 planes intermediates.

diameter the disc for attached balancing weight is 800 mm.

Lenght of shaft is 4 meter.

the issue we meet is our balancing machine suggest to only position at both side .

At the end , we get so much weight to applied to recommend angles.( SEE PICS2)

after that , when we trim vibration to meet the standard (G 6.3 ) it make more vibration .

I checked that the phase at both side  ( vertical) is not change only the value is down.

But on the horizon the value is come up !!!

thanks for get some comment!

 

 

 

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What type/model of balancing device are you using? How many sensors are you using on each bearing for your 2 plane balance? Are you paying attention to with/against rotation for your weight addition? Have you done a 2 plane balance before, the size of this machine, it will take a lot of weight on the ends of the rotor to bring into balance.

Long skinny rotors are difficult to balance, I have balanced several similar mixers about 1/3 the size of your unit with success. Sometimes you have to remove and add weight, find the heavy mixer blade and swap it to the light side in some cases. Sometimes you have to weld flat plate to the main shaft between the blades to get close. MAKE SURE THE SHAFT IS NOT BENT, you can not balance out a bent shaft.

Dave

Thanks Dave!

This bis the second shaft we changed, the first is bent. The tool from Schenk.

U are right , we did balance before with initial value over 120 mm/s NDE  and 100 mm/s at DE.for your info, we balanced succeed almost with the same machine but smaller ( 2.7meter long shaft).

Now they upgrade to new model longer.

Common the procedure for balancing is followed strict.

Thanks

 

Yesterday we remove 50kg paddles on the rotor...and match the value under specs 5mm/s all location in Machine at ful operating speed  socwe accept this value .But Due to check the coastdown we have issue .High peak at 300rpm .IMG_20191128_223245After check the impact test we get a record on the steel frame .

They calculate the natural frequency of shaft at 803rpm.

So the frame of machine need to Reinforce?

 

 

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