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Belleville washer

  1. Jul 2, 2011 #1

    Ranger Mike

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    A Belleville washer, also known as a coned-disc spring, conical spring washer, disc spring, Belleville spring or cupped spring washer, is a type of spring shaped like a washer. It has a frusto-conical shape which gives the washer a spring characteristic.

    Belleville washers are typically used as springs, or to apply a pre-load or flexible quality to a bolted joint or bearing.

    They may also be used as locking devices, but only in applications with low dynamic loads.



    what is the expected life of the typical belleville washer?
    how long until it will loose tension? loosen up?
     

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  3. Jul 2, 2011 #2

    Averagesupernova

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    How long do you need it to last? I've seen them used in slip-clutches before and typically if they do not overheat they last indefinately.
     
  4. Jul 2, 2011 #3

    turbo

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  5. Jul 3, 2011 #4

    Ranger Mike

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    Thanks for the input..the machine tool application is to locate air bearings on an aluminum guide way. the machine has movement in X , Y and Z direction. It seems to me that over time the washer would relax and the air gap would increase. Aluminum expands with temperature and the washers prevent galling of the aluminum i guess...
     
  6. Jul 3, 2011 #5

    Q_Goest

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    Hi Mike,
    I don't think there will be any creep in the material unless it's operating at very high temperature, but since it's mated with aluminum, it doesn't sound like your temperature will be that high. Steel (and virtually any material) can be subject to fatigue which is the gradual development of cracks in material due to cyclic stresses and you've indicated that may be the case here. But fatigue generally doesn't cause the material to change dimensions until the crack grows to the point of breaking, at which point you have a catastrophic failure. What may be an issue in this case is movement between the steel belleville washer and the aluminum. When you have movement between two parts, regardless of material type, there's often some kind of wear between the two. One or both parts begins losing material, so the joint would loosen up over time. So I think to answer your question, you shouldn't expect the washer to change shape over time unless you have stresses so high you get yielding or failure, and belleville washers are generally designed to go flat without yielding.
     
  7. Jul 3, 2011 #6

    enigma

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    When overstressed, I have seen stacks of Bellevilles 'flip' direction.
     
  8. Jul 4, 2011 #7

    turbo

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    Really? That would be pretty wild.
     
  9. Jul 4, 2011 #8

    Ranger Mike

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    The application in this scenario is similar to the attached pic. The air bearings are gliding over the precision surface..in the illustration a 2 micron air gap is used when GRANITE ways are used..the air gap goes to .0254mm (.001") or even 0.003" inch when aluminum is used..hence the belleville washer is used...but is this not a DYNAMIC application...exactly whet the washer manufacturer advises against?

    hey..it might be nit pickling but is concern not valid in this case?
     

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