ฝึกพูดภาษาอังกฤษด้วยเทคนิค Shadowing จากวิดีโอ: An Animated Introduction to Vibration Analysis by Mobius Institute

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Hello and welcome to this webinar an animated introduction to vibration analysis.

My name is Jason Tranter the CEO and founder of Mobius Institute.

Very briefly I've been involved with vibration analysis for over 30 years living

and working in Australia and the United States and I've been involved over

that period of time in vibration analysis condition monitoring

and reliability improvement both doing the work developing monitoring systems

and for the last almost 20 years providing training in the field and

so my company Mobis Institute I'll just take a brief moment to say

we offer training in the areas of reliability improvement lots of

training in the area of vibration analysis almost 4 000 people

a year all across the world in 60 70 countries the students come from we offer certification

that is accredited to the iso standards

and we also run a conference called the international machine vibration analysis

and condition monitoring conference we run that conference in the united states australia singapore

which at the time of this recording is coming up in just over a week and in Europe.

And yes, we have offices and training centres all over the world.

So let's talk about vibration analysis.

You know, equipment failure happens.

I'm sure if you're listening to this, you're already well aware of that fact.

The question is, how do we avoid it?

How do we catch signs of the bearing failing

or anything else failing via vibration analysis so that we can manage the repair process? we can plan and schedule that process.

So the good news is that when we're dealing with rotating machinery like this, as the rolling elements roll around inside the bearing,

they make a certain vibration that the forces involved create a certain vibration pattern when there's a problem.

When there's not a problem, actually they don't really create any vibration for the most part.

The same can be said for timing gears

or normal gears in a gearbox as those teeth there mesh together they create a vibration pattern

and if there's a problem with the misalignment with the teeth

or anything else it creates a vibration pattern and

that goes for almost every rotating component in the case of our more sophisticated gearbox the compli the vibration

I should say is more complicated but we can still diagnose an awful lot from a machine like this even complicated

wind turbines that can vary in speed that can have very complicated gearboxes

and low speed bearings high speed bearings you name it vibration analysis lets us see inside the machine

so to speak so that we can tell exactly what's going on we can detect the changes

and then decide what to do about it when we see the changes.

So I mentioned a moment ago that vibration lets us see inside the machine, so to speak.

So if you just listen to a machine, it might make a sound like this.

And hopefully you can hear that okay, and the pump may make a certain sound.

That's not a very healthy sounding pump.

But what vibration analysis allows us to do is break

that sound up into all its individual components because those individual frequencies actually relate to different components within the machine.

And as those frequency components change, it provides an indication of whether there's a problem with the bearings

or the rotor bars or the shaft which can be misalignment, unbalance or anything like that.

Now I'm just simulating the sounds.

They'd be actually more pure than that in reality.

But if there was a problem with the bearing, okay, we're just listening to it.

But the vibration pattern would change.

If there was a problem with the alignment, balance, if the shaft was bent or something like that, we would see it.

If there was a cavitation problem.

well we would be able to detect that through vibration analysis as well

and if there's a problem on the machine head I wish all machines made

that sound but yes we could detect that too yes okay

so imagine what we're going to do even though

when we look at a machine we don't see it moving like

that we pop a sensor on top of the machine and

that periodic motion you can see the machine sort of vibrating up and down creates a, a Simple signal.

That little sine wave you see there has an amplitude and frequency.

And of course, if the problem got worse, then it's a bigger waveform.

And in this case, it's actually going up and down more slowly.

So it's a different frequency.

But we can learn an awful lot from a simple signal like that.

But in reality, of course, the vibration from a machine is more complicated.

So let's take a little bit more of a look at how we collect the data just briefly.

So there's our machine.

Now as I mentioned before, you know the motor makes certain vibration, the pump makes certain vibration.

And what's actually happening is as the shaft turns there's magnetic forces in here,

electromagnetic forces, there's the bearing vibration, the fan vibration, the vibration of the rotor bars and

so on and all of that transmits along and goes up through the bearing to the housing.

So up through the bearing to the housing and so on.

So we literally place this vibration sensor that converts the vibration into an electrical signal into our measurement device.

So in the case of a portable vibration analyzer, we can walk from machine to machine,

pop it on top and either get a simple readout of vibration

or a more sophisticated spectrum which you can see very simply depicted there.

But one little thing to understand is a machine like that actually vibrates up and down.

It vibrates side to side, so we need to measure that sideways motion.

And it actually also vibrates end to end, i .e.

axially.

So it really helps to get the vibration from the three axes,

if we can, that way we can tell exactly what's happening with the machine.

Often you can get away with just a horizontal measurement and an axial, but the fact is that with different sorts of machine faults,

the vibration changes in different ways in different axes and

so that's why we like to measure on different bearings ideally on both bearings of the machine component

and in different axes

if we possibly can to get the full picture of the machine vibration you know

if this bearing had a problem the vibration may not transmit through the shaft to this bearing particularly

if it was a flexible coupling or something like that so instead we we

We take our measurement here, we take our measurement there, and then we get the complete picture.

So this is a very simple view of what the vibration is all about.

So imagine the shaft within the machine in a very simple example like this.

We're depicting the machine having unbalance.

So the shaft is actually trying to move in a circular motion.

We're looking axially along the shaft here, so the shaft's in profile.

And imagine if you could just get a dial indicator, place it up against the shaft, and see that motion.

So of course if it was safe, and it was moving slowly like that, and it had that much amplitude,

and we could trace out that variation in displacement, we would see that sine wave

that we saw just before now we can look at different sorts of vibrations

so for example

if it had fan blades as well then this vibration

we're seeing now may be the vibration just due to the the blades of the fans

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so with each rotation of the shaft you know we've got six blades there

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so we get six times as much vibration

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or I should say the frequency is six times as much

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and if we consider the reality of a situation like

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that where we're seeing the motion of the shaft

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and the vibration due to the fan blades well

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we get the two added together

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now as you can see it's becoming a little bit complicated this is actually called the time waveform

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and we'll look a bit more closely at the time waveform a little later you know

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if the machine speeds up the frequency changes it goes up if the machine slows down then the vibration changes.

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In this example the amplitudes didn't change but the frequencies change

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because it's going slower and of course we could change the amplitudes as well.

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Now in reality well actually with some machines with fluid film bearings,

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journal bearings, we can actually take a displacement measurement you know it's a sensor there

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that can detect that distance but otherwise you know for normal walk around balance of plant machines we use the accelerometer

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So, okay, we've seen this vibration.

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Let's look at that in a little bit more detail.

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So here's a machine, and let's just assume that we're going to take some measurements on the bearing there.

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So, if we were to look at the vibration in reality, it could be really quite complicated.

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Now, this is a simulated little signal here, but the signal tells us an awful lot.

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That raw vibration, that time waveform there does tell us a lot.

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But let's just go back to basic principles.

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Let's keep it really simple and just say, let's break up that vibration into its raw components because by doing so,

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we can explain or describe the most common type of presentation of vibration information and that's called the spectrum.

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And that's what most vibration analysts look at every day.

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But it really helps if you understand where the spectrum came from.

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So, let's have a look.

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Imagine, if you will, that that motion you can see there in the animation from the shaft turning

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Now just for the sake of this demonstration, you can even see the shaft is bent

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Once per revolution it makes that cyclic motion

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It would make a similar motion if it was out of balance as well

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So there's our little simple sine wave

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And we can speed up the machine a bit, you know, make it a bit more interesting sine wave

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Okay, so that's one source of vibration.

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And if it was out of balance, there'd be a lot of vibration.

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And if it was, you know, perfectly balanced, there'd be just a tiny bit of vibration.

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So there's one source.

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And this is all being measured right off that bearing there.

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What I'm going to simulate is the situation we saw just a moment ago.

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I'll just give that a bit more vibration.

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With the fan.

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Now, it's an orange fan.

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So let's make some orange vibration.

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Let's say there were 14 blades on the fan, I forget how many there are actually,

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but we get then 14 little pulses of vibration for every rotation of the shaft.

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Now we're not measuring over here, this vibration that's generated because there's something maybe the blades are bent or something like that,

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that vibration transmits through to the shaft up here to our measurement location.

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Now, in addition to the fan vibration and the shaft vibration, so the grey shaft creates this grey vibration, the orange fan makes the orange vibration,

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well the green bearing, just to really simplify things, it also creates vibration.

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Let's just turn off the other one so it's a bit easier to see.

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And this is the green vibration from the bearing.

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Now, as I mentioned a moment ago, if the bearing is in tip -top condition, then we don't expect to see any green vibration

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when you start to see some green vibration you say oh wait a minute there's something wrong with the bearings

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if the vibration gets worse and worse and worse at

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that frequency which is different to that frequency and it's different to

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that frequency they generate different frequencies

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and you know depending on how bad the problem is we can see higher or lower amplitudes.

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Unfortunately, it's more complicated than this.

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Not only do bearings create a very different vibration pattern for that, but in simple terms, they do have their unique frequency.

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But what we measure is the combination of the gray, the green, and the orange vibration,

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which looks something like that that more complicated squiggle line there the time waveform is the combination of all those motions

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and so that's what the vibration analyst gets out of

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that sensor that's placed on the bearing

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and it's like okay what can we do with

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that well let's take

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it a step further what we're seeing here is an overlay of those three sources of vibration

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that we've been talking about you know the shaft the bearing

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and the fan what I'm going to do is look at

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that in three dimensions

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so there is time along here as time passed by the machine vibrated up

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and down and it you know vibrated because of the bearings

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and it vibrated because of the of the fan I'm just gonna back

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that off just a little bit there

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so that's what happened over a period of time the up and down or y -axis is the amplitude of the vibration.

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But each of these represents a frequency.

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And our spectrum, which is the most common tool used by vibration analysts, is as if we look at the vibration from this axis.

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You can hopefully see my mouse moving.

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And so if I change the speed of the machine, you can see the waveforms all change in frequency.

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If I change the amount of fan vibration, you can see that one go up whoops I went too far

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and and you can see the changes or the unbalanced vibration let's say

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So what I'm going to do now is change my view of this data from this angle, and that is the spectrum.

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And if I just take a little bit of a better view of it, there again is the vibration just due to the shaft turning.

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There it is due to the bearings, and there it is due to the fan blade vibration so

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if my original measurement on the machine looked like that

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and then the next time I tested it looked like that

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and the next time I tested it looked like

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that I'd say well that once per revolution vibration probably due to unbalance is increasing

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if my original vibration looked like that there's no bearing vibration

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and the next time there was more

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and then more I'd start to become concerned

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that the bearings were going to fail and now with

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that early warning I can go and start the the planning process to replace

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that bearing so

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that it can be ordered you know it's a rather nice having to keep

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it in our own spares inventory we can order

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it from the vendor have it here in plenty of time

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plan the job keep the job find the right people

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and tools and all those are the things that we want to do

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so that there is the basics of the the spectrum

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which as I mentioned is the most powerful tool in vibration

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but we can go further

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so let's do go further first you know the different fault conditions do present different patterns

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so you know this little very simple

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and idealistic looking spectrum is just a peak rather than talk

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about it in terms of frequency vibration analysts often talk in orders 1x just simply means

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it's 1 times the speed of the machine

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so unbalance as we've just learned happens at the running speed of the machine

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so we call it the 1x peak so

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if there was unbalance we expect that peak to increase in amplitude it turns out

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that if the machine is misaligned now this is all just very simplistic for the moment, we might see a pattern like that.

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The 2x vibration.

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The vibration at twice running speed will increase.

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There may be some vibration at three times.

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If the bearing was loose in the housing, let's say, or there was excessive clearance,

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then we get a whole lot of peaks and the bottom of the graph lifts up.

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If we had a fault with the bearings, okay, there's that that green peak we talked about

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but it's really common to see a peak at twice that frequency BPFO that should say three times and four times.

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We can have a problem called resonance and that might also make

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that peak go up but the base of the peak broadens out.

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Anyway the key takeaway here is

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that the spectrum tells us about the nature of the fault

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and the severity of the fault and we can take

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that information we can watch how the vibration is changing

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and then we can make the recommendation

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that you know does the bearing need to be replaced is

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it a problem with damaged rotor bars is the problem with the coupling is there a problem with the foundations

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I mean all kinds of problems can be detected this way

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now we need to talk about another aspect of vibration analysis

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and that's what we can learn by detecting very high frequency vibration

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because it turns out that

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when the bearings just start to fail we can't see any sign of

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that failure using a normal spectrum instead

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if we tune our vibration monitoring system to a very high frequency

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and we go through some transformations

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which in case you've heard about it could be called demodulation

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enveloping shock pulse HD peak view spike energy HFD Swan C you know there's a lot of different technologies

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that utilize the fact that if for example we had some damage in the outer race

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if it don't go to a bigger picture of it

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if we had some damage like a little ball

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or a little crack

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or even a subsurface defect each time one of the rolling elements rolls over the top

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we get this ping of vibration it's very quick

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it rushes through the metal of the machine it's very low amplitude

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so it's hard to detect very high frequency

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but the vibration analyzer can pick it up

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and it can provide a pattern to the vibration analyst to give them

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that very early warning and then we can you know monitor the progress of

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that fault you know

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if it's a very critical machine perhaps high speed high load it could fail quite quickly

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or we hey we could get a year

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or more warning of a problem like this and therefore we can plan

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and schedule you know to suit our production requirements and so on But if you watch, there's a certain periodicity to this.

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See, ping, ping, ping, ping.

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Well, it turns out that if the damage was on the inner race of the bearing, you can see it's a different frequency.

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Ping, ping, ping, ping, ping, ping.

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That's called the ball pass inner race frequency.

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It's a different frequency.

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And if there's damage on the rolling elements themselves, then it's a different frequency again.

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And that's why a vibration analyst doesn't just say, oh there's you know the there's bearing damage the analyst can

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actually say whether it's on the inner race outer race

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or the rolling elements now it's not that you're going to go

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and buy a new set of rolling elements

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or a new in a race or something like that

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but knowing that information can really help in the planning

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and scheduling process and hey

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if you've got big expensive bearings people have been known to

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you know in this instance to actually just rotate the outer race to take

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that damaged area out of the load zone

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because it's quite common to have failures down in this area because it's under so much load for a horizontally oriented machine.

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Anyway, moving along.

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So we can use that information and detect faults quite early.

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Now I just want to briefly mention that there is another approach to vibration analysis.

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I just want to briefly sort of summarize a few things

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so if this was our spectrum what I'm doing is it's kind of simplifying things

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and this this frequency scale it's sort of log with me you know ten thousand twenty thousand

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so we tend to get this very high frequency vibration out here the stuff

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we were just talking about we get some peaks down low

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and those peaks often relate to problems like unbalance misalignment looseness

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and so on

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and then often in this sort of mid -range frequency in fact

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we can sort of divide it up into low mid high

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and very high frequencies we might get a different set of faults you know problems with the impellers

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and blades and so on

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and then higher frequency problems with gears the rotor bars the stator slots now there's other faults

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that have higher frequency and then we can get into lubrication faults and

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and very high frequencies you know cavitation lubrication bearing damage

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now there is a way just to get started with vibration analysis

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that rather than using the more sophisticated spectrum we can just take this this velocity overall level vibration

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and it just kind of says well hey without going into any detail of what's going wrong with the machine

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we can just talk about the actual vibration amplitude

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we can focus on just the low frequency vibrations let's just get rid of those little messages,

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by focusing on the vibration in units of displacement, or units of acceleration focuses on the higher frequencies,

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and we can even go into the very high frequencies as a single reading

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to tell us what's happening with lubrication and bearings and so on.

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So we can have this simple reading just to trend.

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It gives us an idea of what's going wrong, but none of the real details.

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So let's keep going.

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So, so far we've learned

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that the spectrum does break all those frequencies up into their individual components so that we can see faults like, you know, specifically unbalanced, misalignment,

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looseness, foundation problems, and so on and so forth.

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Now, that's great, but time waveform analysis gives us a perspective of what's happening

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that you can't really get from the spectrum alone.

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So imagine in this case, if you ever recorded your voice and looked at that waveform from your voice,

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this is sort of what we're talking about.

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This is what is happening from moment to moment.

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So, in this instance, you can see these damaged gear teeth.

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so there's the vibration

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so in here in here in between those spikes in other words that's the vibration

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when the good teeth go through the mesh but

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when this these chipped teeth damaged teeth go through the mesh we get this big spike

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so once per revolution we see a big spike

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because there's only one area of damaged teeth

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so I can look at this I can look at the the G's level the sort of peak acceleration level

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and I can detect the severity of the problem

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and I can see things that are very hard to see from a spectrum alone

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so time -way form analysis really complements

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the spectrum analysis and vibration analysts that are sort of masters of their domains

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so to speak you know i would like to think they would use this time waveform analysis

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and you know it's just the same thing we saw before it's just taking

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that that vibration and breaking it down into you know the you know

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but rather than breaking it down

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and just looking at the spectrum we can look at the raw waveform all by itself

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so again you know if we

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if we had a fault for example with the rolling elements well there it is

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and we see something curious in this case

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because as the balls roll into the load zone there's more force down there

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and we get this bigger pulsations when the

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when the damaged balls roll around up out of the load zone up at the top of the bearing

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then we get weaker vibration

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so the top of the bearing represents where the amplitude is small in

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that pulsating waveform at the bottom of the bearing for a horizontally oriented machine we get the bigger pulses now

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that does translate into a certain pattern in the spectrum

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but we can see it beautifully clearly in a time waveform as the gears mesh together ideally

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that force would be uniform but

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if you look closely at the animation you can see

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that this is actually eccentric or it could be bent

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so the force in that mesh gets stronger and weaker stronger

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and weaker and we can see

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that in a time waveform as well those pulsations

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you can see occur as the teeth go into sort of

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a stronger mission a week in mission a stronger mesh

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so it really complements what the analysts can do with the spectrum alone

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and in this instance we've got the the excessive clearance in the bearing

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and we can see it rattling of course my animations really exaggerate things

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but we get a time waveform with these great big spikes you know in

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that instance it might have been once per revolution maybe

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and we'll see you know bang bang bang bang bang all those spikes yes in the spectrum

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we see all these peaks they're called harmonics it's very common in this case

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but it's really good to be able to look at the time waveform as well

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and there's our tooth damage which one we saw earlier.

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But that waveform is what it should look like.

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Now, the amplitude looks really high.

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It's just that the scale is different.

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So that vibration is just kind of normal vibration, low amplitude even though it's been made to look bigger.

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So if we saw a waveform like that, who cares?

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It's telling us that everything's cool.

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Now, there's one more form of vibration analysis.

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In fact, I'm going to tell you that two more, but there's one more that's really helpful and that is phase analysis.

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It tells us about the motion of the machine as it responds to the damage within the machine.

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So for example, if we had unbalance or misalignment, eccentricity, bent shaft and the other faults that you can see there,

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it actually causes the machine to move.

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It may rock from side to side,

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bounce up and down, move axially back and forth and we can see specific sort of movements in the bearings themselves.

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And so rather than just looking at the spectrum, we can look at these phase measurements that give us an idea of the motion.

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We can do it in a couple of ways.

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This is the more difficult way.

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We put a piece of reflective tape on the shaft.

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We use this to detect the once per revolution vibration, and we compare the vibration patterns from a timing point of view.

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Look, that's just the complicated way.

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You can use strobes as well, but by putting an accelerometer, two accelerometers on the machine, in this case, one measuring vertically,

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one measuring horizontally, we can see how that bearing is moving.

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Is it moving in a circular motion or is it more elliptical or side to side or up and down?

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We can tell.

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And there's an awful lot we can learn we can take these phase readings

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so they are values between 0 and 360 you know a circle has 360 degrees

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and we use these these diagrams

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so for example rather than just looking at all these complicated numbers we can use a little symbol like

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that this little tail points off it's like a compass

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so this is pointing off at 18 degrees this is pointing off at 21 degrees now that's all sounds complicated

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but all that means because they're basically pointing in the same direction

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that just means that both ends of this machine are moving up

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and down in phase with each other

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they're both moving up together down together in some fault conditions

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we'll get one end of the machine moving down as the other end of the machine moves up

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or it may move down on one side of the coupling

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at the same time as it's moving up on the other

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when there's misalignment so this all may seem a little complicated it's just worth knowing

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that measurements like this exist that for example here you can see

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that these ones are pointing down well it's sort of down at

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that 45 degrees that's not 45 but if i compare this one to

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that one you can kind of see that there's about 90 degrees between these two and we only see that with unbalance.

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It might seem strange you know because it's moving in a circular motion

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and so on why wouldn't that always be the same?

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Well with misalignment and just about every other fault condition we see different motions of the machine.

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So now we have another weapon at our disposal.

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We can use the spectrum which gives us an indication of the fault condition and the severity.

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The time waveform provides extra detail and in certain circumstances it provides really important detail.

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And with certain fault conditions to tell, hey, is it misalignment, is it out of balance, is it resonance, is it looseness?

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There's just these faults

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that can kind of look the same with the spectrum

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this phase analysis helps us pinpoint exactly what's wrong with the machine

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so we only need to do this

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if we're really not sure what's wrong with the machine

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but we're pretty sure something's wrong so it's a really useful tool

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so in this instance this is a rotor

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that we call it static unbalance it's just like I add a balance in one plane

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if we look at this motion we see you know

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if we if we look at that both bearings are moving up

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and down together that's in phase

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if we look at this bearing here you can see it's moving in a circular motion

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so we can draw those little symbols

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and say yep end to end it's in phase from vertical versus horizontal

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there's a 90 degree change okay I'm not trying to teach you vibration analysis just show you

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that these measurements can be put to good use

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this is a more complicated situation where we have a longer road out of balance

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but actually this bearing is still moving in a circular motion it's just

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that from one end to the other it's not either perfectly in phase

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or perfectly out of phase

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it tells us how severe the problem is though it tells us how we need to go about balancing

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this machine in this case we've got an overhung rotor

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and we see something else that's curious not only is

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that rotor actually trying to move in a circular motion it's actually rocking back

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and forward which creates an axial force in this direction

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so we take our phase readings on the sides of these bearings

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and we can tell what's wrong with

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that fan in this case this machine as you can see is slightly misaligned

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I sure hope your machines don't look like that

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but hey I just have to exaggerate the animations but imagine now

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if you can see there that if I took a vibration reading here

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and here at the same time the motion is

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that they are out of phase with each other and

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that will tell us okay the machines misaligned with axial misalignment we get

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or angular misalignment we get an axial force and again phase would confirm

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that hey here we've got the inner race of the bearing

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and perhaps it's been hammered into place it's cocked on the shaft

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that will cause the bearing to fail but we can use phase analysis

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and tell that that's the problem

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because from pure spectrum analysis it's hard to tell now just in case you work in oil

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and gas or power generation

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or other applications where you have critical machines with fluid film bearings

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there is another type of vibration reading we use called orbits analysis

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so particularly for large turbines it's critical

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that we understand how this is moving as it rotates

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and we we want to know

444

you know what's happening at the bearings is it moving in

445

a circular motion is it is the shaft in the correct

446

position within the bearings there's all this complicated stuff we need to know and the orbit

447

tells us that

448

so we're actually using two proximity probes two displacement probes to tell us about the radial motion

449

and we use another proximity probe commonly called a key phaser

450

which is in a position to pick up a once per revolution event in this case a keyway

451

and with this timing information

452

and these two probes we can tell exactly what's happening with the rotor where it is inside the bearing

453

which is really important

454

and is it moving in a circular motion a large circular motion during due to unbalance a small circular motion

455

because it's properly balanced is it elliptical and highly elliptical

456

because of preload from misalignment or something like that there's so much we can tell

457

when the machine goes through its first critical

458

and maybe second critical speed it will actually flex not quite as much as what we're seeing here

459

but our orbit measurements

460

tell us what's going on so basically if this was a very exaggerated end view of that rotor we are

461

very interested to know what the center of the shaft is doing

462

and so we can see it now it's it's drawn out this orbital motion

463

and that's actually what those two proximity probes give us

464

when we look at an orbit now just for illustrative purposes

465

we've got orbits at different points along the machine we wouldn't necessarily have probes at those locations

466

but anyway just for illustrative purposes the little orbit diagram tells

467

us how the machine's moving how much the the rotor is moving relative to the bearings

468

or relative to the probes and and the phase relationship

469

and other really useful information anyway

470

if you ever hear about orbits

471

this is what it's about we we have two probes

472

I'll just slow the rotor down put our little probes on

473

there now the probes could be located at this location

474

or this location or other locations the key phase it can be mounted in different places

475

but anyway depending on the vibration pattern

476

and the forces on the machine we will see different shapes

477

so for example we may see more vibration actually I would probably say more vibration in the x -axis

478

because of the loading

479

and maybe it's got elliptical bearings we can see interesting sort of phase relationships hey

480

we can see all kinds of things depending upon what's happening with our machine it's a really useful measurement

481

and there are other measurements we can take on these sorts of machines as well anyway

482

this is just to sort of I guess open your eyes to all the sorts of measurements

483

we can take depending upon the type of machine

484

and what it is we're trying to learn so rather than looking at just a very simple

485

overall level vibration

486

which gives us a very crude idea of of how the vibration is changing the spectrum the time waveform phase and

487

if appropriate the orbit measurement really helps us to understand what's happening inside the machine

488

it puts us back in control okay

489

it doesn't necessarily stop the machine from developing the fault in the first place

490

that's for a different discussion about reliability improvement

491

but vibration analysis gives us an insight and now we can decide you know

492

if there's something we can change about the way the machine's being operated

493

if there's something simple we can do to alleviate the problem to extend the life of the machine

494

or we can start planning the maintenance it's much better to do it

495

that way than to find out oh gosh we've got another problem I've machine just failed

496

or it's gonna fail soon and now that's an extremely costly process

497

because of the spares

498

we have to keep the downtime the potential safety risks all the extra maintenance work

499

that's going to be required to deal with it vibration lets us get the information

500

we need to make those important decisions

501

so in conclusion vibration analysis is very powerful it provides an indication of the nature

502

and severity of the fold condition and it has been used in every industry all over the world for many years

503

but I would like to reinforce

504

that vibration analysts should not rely on just one technique alone like the spectrum is useful but there are other tools

505

And it's worth saying also at this point that there are other condition monitoring technologies.

506

Looking at the oil samples for maybe the quality of the oil, the condition of the oil, but also are there any wear particles,

507

any little bits of metal because the gears or bearings are damaged.

508

We can listen and analyse ultrasound.

509

We can perform special tests on the motors.

510

We can look at temperature there are other ways to assess the condition of the machine.

511

But it is essential that the analyst understand the machine, the analyzer, the vibration measurement system.

512

the failure modes as they're called, the fault conditions themselves, and the plant's business philosophy.

513

I mean, particularly when it comes to the idea of condition -based maintenance, but just understanding what the company is trying to achieve.

514

On one hand, we can just say, we're just going to measure the vibration, see it change, and then say,

515

okay, the machine needs to be taken out for repair or overhaul.

516

On the other hand, we can do a Spock mind meld with the machine

517

and truly understand why the vibration changes when the condition of the machine changes.

518

And that totally transforms what you can achieve with vibration analysis.

519

Anyway, enough said.

520

I hope you have found this presentation or this webinar useful and I look forward to answering any of your questions.

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วิดีโอแนะนำ

197 ประโยค

คำศัพท์และข้อสังเกตด้านการพูดสำหรับบทเรียนนี้

บทเรียนฝึกพูดนี้ใช้วิดีโอ “An Animated Introduction to Vibration Analysis by Mobius Institute” เป็นสื่อ คำที่ถูกพูดซ้ำบ่อยที่สุด: vibration, machine, bearing, analysis, frequency วิดีโอนี้มี 520 ประโยค และ 6449 คำ สำหรับฝึกพูดตาม ช่วงที่มีเสียงพูดยาว 40:50 ผู้พูดพูดด้วยความเร็วเป็นธรรมชาติ ประมาณ 158 คำต่อนาที ใกล้เคียงกับบทสนทนาในชีวิตประจำวัน 83% ของคำอยู่ใน 3,000 คำที่ใช้บ่อยที่สุดในภาษาอังกฤษ ส่วนที่เหลือควรดูไว้ก่อนเริ่มฝึก

คำศัพท์สำคัญในวิดีโอนี้

คำที่ควรเรียนรู้ 15 คำจากวิดีโอ พร้อมคำอ่านและความหมาย:

คำศัพท์	คำอ่าน	ความหมาย
vibration คำนาม	/vaɪˈbɹeɪʃən/	การสั่นสะเทือน
frequency คำนาม	/ˈfɹiːkwənsi/	ความถี่
spectrum คำนาม	/ˈspɛktɹəm/	สเปกตรัม
bearing คำนาม	/ˈbɛɹɪŋ/	ลูกปืน
shaft คำนาม	/ˈʃɑːft/	เพลา, ทูบ
complicated คำคุณศัพท์	/ˈkɑm.plɪˌkeɪ.tɪd/	ซับซ้อน
blade คำนาม	/bleɪd/	ใบ, มีด
orbit คำนาม	/ˈɔɹ.bɪt/	วงโคจร
monitor คำนาม	/ˈmɑ.nɪ.tɚ/	จอภาพ, หน้าจอ
bend คำกริยา	/bɛnd/	งอ
animation คำนาม	/ˌæn.ɪˈmeɪ.ʃən/	แอนิเมชัน
pump คำนาม	/pʌmp/	เครื่องสูบลม, เครื่องสูบน้ำ
pulse คำนาม	/pʌls/	ชีพจร
axis คำนาม	/ˈæksɪs/	แกน
axe คำนาม	/æks/	ขวาน

กริยาวลีที่คุณจะได้ยิน

คำศัพท์	ความหมาย
pick up คำกริยา	ยก, หยิบ
turn off คำกริยา	ปิด, ดับ

ประโยคที่ควรฝึกพูดซ้ำ

ประโยคสั้น ๆ ที่สมบูรณ์จากวิดีโอ ซึ่งนำไปใช้ในบทสนทนาประจำวันได้:

The question is, how do we avoid it?
We're depicting the machine having unbalance.
I'll just give that a bit more vibration.
It's telling us that everything's cool.

ไวยากรณ์ในวิดีโอนี้

โครงสร้างที่ผู้พูดใช้บ่อยที่สุด พร้อมคำพูดจริงจากวิดีโอ:

โครงสร้าง	ในวิดีโอ
ประโยคเงื่อนไข if + อนุประโยค, will/would + กริยา — เงื่อนไขและผลลัพธ์	if it was out of balance, there'd be
Present perfect have/has + กริยาช่อง 3 — เหตุการณ์ในอดีตที่ยังเกี่ยวข้องกับปัจจุบัน	I've been involved · we've seen · we've just learned
Passive voice be + กริยาช่อง 3 — เน้นสิ่งที่เกิดขึ้น ไม่ใช่ผู้กระทำ	I've been involved · is accredited · can be said
Relative clauses who / which + อนุประโยค — ข้อมูลเพิ่มเติมเกี่ยวกับคนหรือสิ่งของ	shaft which can · frequency which is · spectrum, which is

การออกเสียงที่ควรระวัง

ผู้พูดใช้รูปย่อและรูปลดเสียง 73 ครั้ง เช่น we're, we've, I'm ให้พูดแบบสั้นตามที่ได้ยิน

เสียง “sh” และ “zh”: vibration /vaɪˈbɹeɪʃən/, shaft /ˈʃɑːft/, measurement /ˈmɛʒ.ə.mənt/, mesh /mɛʃ/, animation /ˌæn.ɪˈmeɪ.ʃən/
คำยาว — ลงเสียงหนักให้ถูกพยางค์: complicated /ˈkɑm.plɪˌkeɪ.tɪd/, animation /ˌæn.ɪˈmeɪ.ʃən/, severity /səˈvɛɹ.ə.ti/, indication /ɪndɪˈkeɪʃən/, proximity /pɹɒkˈsɪm.ɪ.ti/

เสียงที่คนไทยมักออกเสียงยาก:

เสียงท้ายคำ — ออกเสียงให้ครบ ไม่เปลี่ยนเป็นตัวสะกดแบบไทย: mesh /mɛʃ/, awful /ˈɔːfʊl/, pulse /pʌls/, axis /ˈæksɪs/, axe /æks/
/v/ — ไม่ใช่ /w/ ให้ฟันบนแตะริมฝีปากล่าง: vibration /vaɪˈbɹeɪʃən/, severity /səˈvɛɹ.ə.ti/, relative /ˈɹɛl.ə.tɪv/, excessive /ɪkˈsɛsɪv/, versus /ˈvɝsəs/
/z/ — เสียงก้อง ไม่ใช่ /s/: presentation /ˌpɹɛzn̩ˈteɪʃn̩/, horizontal /ˌhoɹəˈzɑn.təl/, resonance /ˈɹɛzənəns/, disposal /dɪsˈpoʊ.zəl/, analyzer /ˈæn.əˌlaɪ.zɚ/

วิธีฝึกกับวิดีโอนี้

ฟังวิดีโอให้จบหนึ่งรอบโดยยังไม่ต้องพูด แล้วจดคำที่ยังไม่รู้จัก
เริ่มที่ความเร็ว 0.75× พูดตามทีละประโยค แล้วกลับไปใช้ความเร็วปกติเมื่อเริ่มคล่อง
อัดเสียงตัวเองแล้วเทียบกับต้นฉบับ โดยสังเกตคำอย่าง vibration, frequency, spectrum เป็นพิเศษ

เทคนิค Shadowing คืออะไร?

Shadowing เป็นเทคนิคการเรียนรู้ภาษาที่ได้รับการรับรองทางวิทยาศาสตร์ พัฒนาขึ้นสำหรับการฝึกนักแปลมืออาชีพ วิธีการนี้เรียบง่ายแต่ทรงพลัง: คุณฟังเสียงภาษาอังกฤษจากเจ้าของภาษาและพูดตามทันที — เหมือนเงาที่ตามผู้พูดด้วยช่วงเวลาห่าง 1-2 วินาที การวิจัยแสดงว่าเทคนิคนี้ปรับปรุงความแม่นยำในการออกเสียง ทำนองเสียง จังหวะ การเชื่อมเสียง การฟังเข้าใจ และความคล่องแคล่วในการพูดได้อย่างมีนัยสำคัญ

เทคนิค shadowing: อ่านคู่มือฉบับเต็มทีละขั้นตอน →

ฝึกพูดภาษาอังกฤษด้วยเทคนิค Shadowing จากวิดีโอ: An Animated Introduction to Vibration Analysis by Mobius Institute

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