As I said before, its a complex situation and not normally solved in a few days.
Items 3 and 5 are related. In our mill we found that older work rolls were consistently involved when we had chatter. One solution was to use all newer work rolls when we had chatter. For some critical products...
Its been years since I did Chatter investigations on a 4 stand Cold Mill. There are many conditions which cause the mill to go into Chatter but it takes time and measurements to sort it out.
Some observations and comments I have are:
1) Its interesting that the work rolls do not show chatter...
Not much information to work with so I have questions.
Is the vibration problem on the compressor or is it the support beam?
What is the overall vibration at the compressor? Higher or lower than the support beam?
I agree with StrykerTech that frequency info is required.
Taking a shot at...
Just a quick comment.
Time Domain Analysis has been around a lot longer than a few years. It just had a different name but is the same thing.
It was called the "Chart Recorder". You got amplitude versus time. Faster paper speed equals more resolution. Chart recorders were around long...
The basic equation is in "Noise and Vibration Control Engineering" by Beranek and Ver. A simplified form is below.
Lp = Lw - 20 log (r) + DI -11
Lp = sound pressure level.
Lw = sound power level
r = distance from source to receiver
DI = directivity index. Use 3 for free field (outdoors)...
The short answer to your question is Yes.
You need to make/determine a few parameters.
1) Distance to the sound pressure level point, (usually 3 feet or 1 metre).
2) Is the measurement point indoors or outdoors. Most contracts just assume outdoor conditions or "free field conditions". i.e...
In the past where there are multiple degrees of freedom, I have used wire rope isolators. I used it in reverse to protect a computer system on a locmotive engine and also to isolate a fan system which was shaking a roof.
See: http://www.enidine.com/Industrial/WireRopeIsolators.html
Just make...
Do you mean specify or design. I don't see why you have to design a new louvre unless you are talking a new product. There are quite a few suppliers of off-the-shelf acoustical louvres out there which can also be made to fit.
Most louvres are 6" to 12" deep and provide a maximum 12 dB...
Somptinguy,
I looked up the solution for a Helmholtz resonator and the equation is:
helmholtz resonance freq = v/2PI * sqrt (A/Vo L)
The v in the equation is the speed of sound in a gas so do you have another equation where the speed of sound is not required?
Interesting Question here are my thoughts:
1) In my experience the noise comes from the vacuum pump itself and the motor. The pipe noise is not usually a problem.
2) OK assuming the pipe noise is an issue, the inlet pipe is operating in a vacuum. What speeed of sound do you use to design the...
You don't mention the frequency(s) of the high vibration, which can provide a significant clue to your problem. However, I have seen the follwing items cause high to severe vibration:
1) Pump shaft runout.
2) Motor overload due to motor damage or pump impeller wear, or a system change (they...
The answer to your question should be covered in the paper:
"Explicit formulas for the calculation of regenerated noise in ducts" by Tim M Marks
The entire paper is available online. Do a google search and you should find the downloadable paper. The link is below but I find that long links...
