Since vibration data contains many hints for
process, result, and prediction, it is one of the monitoring parameters used
for analyzing failures, detecting risks, and extending life. In order to
measure this vibration, you need a sensor, measuring instrument, and analysis
program, but you cannot get the same result by simply turning on the radio and
listening to it without education. Some people ask for analysis after storing
vibration data on a recorder like storing music on a recorder. It seems that
the method of storage was not very important. At this time, I would like to
talk about the following.
Basics for collecting correct vibration data
The
following is basic, but you should know the importance of measurement, and you
will be able to see how the results of measuring without procedures were a
waste of time.
Even if there are measuring instruments and
vibration sensors, if you want to measure the vibration of a target structure
or facility (machine), where and in what direction should you attach the sensor
and acquire data? It can be overwhelming. In fact, there must be prior
knowledge with a lot of theoretical and empirical basis. Selection and setting
of measuring instruments and sensors are important, but data that is not measured
in the right location becomes the basis for error diagnosis. To summarize, the
answer would be ‘a point where the highest vibration state
(position, direction, behavior) can be read well, so evaluation is possible and
it is safe.’
It
is said that the horizontal vibration on the NDE side is high. Where should I
look?
Looking at the components of a rotating
machine, they can first be divided into the
driving part (driving part) side, the driven part (driven part) side, and the coupling (direct coupling, buffer type, belt,
etc.) that connects them. Another connection element may be a gearbox that requires an additional separate coupling.
Since each component is a machine that is all connected and rotates together,
the speed may be different, but vibration is transmitted between each other,
and if any connecting part is incorrect or misaligned, the entire machine
(equipment) is affected by vibration. Therefore, determining what the vibration
is like at a certain location is a very important appointment. Among these, DE and NDE are words that you must know and understand.
DE, NDE and Outboard, Inboard
Naming the location of the
facility is an issue that has already been------
The sound of bands and orchestras resounding in the
concert hall entertains our brains. Unfortunately, we also analyze the sound. A
string instrument that produces sound by plucking the string and its harmonics,
a wind instrument that blows wind and produces a beautiful sound with the
pipe's unique frequency, and a drum of its own size by beating a drum A
percussion instrument that makes a percussive sound, and a keyboard instrument,
a person's vocal cords vibrate, and a person's vocal cords vibrate in the throat...
This is just music, but it is also called 'structure borne noise, air
borne noise' in engineering. What does that mean? is it a guitar? is it a
flute? is it a piano? Is it the sound of drums? Why are the pictures of
railroad rails and wheels below?
The difference between 'structure borne
noise, air borne noise'
1. What is the difference between the sound coming out
of a speaker or mouth and 2. the sound made when hitting a xylophone or drum?
An accelerometer is the easiest
transducer to measure vibration. Since the measurement direction of this
transducer has already been determined, the sensor must be placed in the
desired direction for measurement. It doesn't really matter if it's up or down.
This is because vibration is repeated and if you want to know the relative
movement, you have to use two or more sensors that measure it at the same time anyway.
In this case, the concept of a phase is only additionally required. However,
compared to a single axis vibration sensor, a triaxial vibration sensor
literally means a sensor having the ability to measure the magnitude of
vibration in three axes at the same time. It is
easy to measure and you will be able to identify vibrations in all directions
in a short time.
Advantages and disadvantages of
Triaxial Accelerometer
Triaxial is described as each three-dimensional orthogonal direction
in Z, X, and Y directions (H, V, A directions in the case of vibration
diagnosis of rotating equipment) that are perpendicular to each other. The axes
in each direction have an initial phase difference of 90 degrees from each
other, and the 3-axis vibration acceleration sensor outputs the amount of
vibration acceleration in each direction as voltage. Therefore, it can be said
that the 3-axis vibration sensor has the following advantages.
First of all, it is possible to measure the vibrations in all directions at the same time. It measures the
vibration in each axis direction at the same time without the need to measure
it sequentially with several different sensors or at different times, so it is
possible to prove the simultaneous state at the time and shorten the measurement
time.
Second, it is possible to measure -----
On the other hand, the 3-axis vibration acceleration sensor is at
least twice as high expensive as the combined
price of all three single-axis sensors, and the average probability of failure (MTBF) of the single-axis sensor is shortened to 1
year compared to the manufacturer's recommended 3 years. do. However, in fact,
the piezo-type accelerometer is more robust and less durable than expected, so
it is not easy to check the broken state. Recently, like a gyro sensor, a
modularized sensor capable of measuring 6-axis vibration has already appeared,
and like MEMS, which basically employs 3 axes,
new-technology vibration sensors with clear advantages
of low frequency have already started to lead in price. The day when
MEMS sensors will be used more often than piezos can be seen in the near
future.
In order
to effectively measure vibration and perform predictive maintenance, it is
necessary to find and set the correct measurement point and store the measured
data continuously. A defect in equipment is usually found at the point where
vibration shows the highest amplitude, and this may have directionality or may
be a point that directly expresses the cause. It is a diagnosis. However, the first starting point for this diagnosis is to name the
measurement point, and we will check the internationally common naming
method.
Measurement point selection rules
If data measurement points are marked on
equipment, data are collected from the same location, so trend data has
reliability first. The measuring points should be the
same as those called on the instrument (route) or on the recording paper
(computer file). For example, if the ‘horizontal direction of the motor
half-load side’ was measured and saved by the measuring instrument, there would
be a way to easily recognize this point and express it simply.
BISOPE series 2- How to select vibration sensor and vibration
unit
A vibration problem occurred in the product or
structure. I need to analyze vibration and I know how to
measure it, but what unit should I measure?
By classifying, communicating, and storing data, we want to make a final
decision with AI through big data analysis to know the problem in advance,
analyze the cause, and submit. But, what vibration unit should be selected
here? The problem that always comes up...
Procedure for selecting vibration sensor and unit
Prior to selecting the vibration unit, the selection of
the vibration measuring sensor has priority. Then choose the unit that suits
you. The procedure and review list are briefly summarized.
