The importance of using Vibration meter in industry
The most common causes of vibration in industrial machines are as follows:
1- Mass imbalance
2- Lack of coaxiality in couplings
3- Curved axes
4- Abrasive gears
5- Worn and damaged bearings
6- Motor contact with stationary parts
7 – Electromagnetic forces
8- Hydraulic and aerodynamic forces and cavitation
9- Intensification
Targets Vibration measurement In industrial machinery
A) Troubleshooting and technical inspection of machinery
B) Vibration control
Demand for industrial products is high, so it is needed to make better use of raw materials, high-speed machines and lighter structures; The possibility of resonance is higher in them and their reliability is low, so it is very important to determine the vibration characteristics of the set.
By measurement Frequency Natural set speeds can be selected away from the intensification mode.
By measuring the vibration input and output characteristics of a set, its equivalent mass, stiffness and damping can be obtained.
For the design of buildings, oil rigs, car suspension sets and…; Information about ground vibrations caused by earthquakes, hurricanes, ocean waves, and road surface roughness is important, and there are usually no theoretical methods for this type of vibration.
Tips to consider before measuring vibrations:
1) Measurement purpose: The purpose of measurement includes vibration evaluation of the device
2) Measuring device
3)Calibration : Zero the device in a place where there is no vibration
On the specialized website of Aria Measurement Equipment and Instruments, you can find different types ofCalibratorFind sources including source, pressure, temperature, voltage and current calibrators. . .
Tips for choosing a swingarm:
– Frequency range and amplitude – Set size – Set operating conditions – Data processing type
Some important points about vibration sensors:
– Sensor type: correct sensor selection, according to the sensor specifications
– Proper installation of the sensor
– Proper condition of sensor and cable connections
Advantages and Disadvantages sensor What about a magnetic holder?
Installing the sensor with a magnetic holder on the measuring point provides a wide range of usable frequencies and eliminates the need for the sensor to move during the measurement period. The installation of the sensor is almost faster than the manual maintenance method. However, the surface of the measuring point must be naturally magnetic and free of any oil or grease.
Disadvantages and advantages accelerometer Piezoelectric:
Benefits :
Durable building, insensitive to magnetic fields, usable in any direction, small size, stainless steel body and impermeable
Disadvantages :
Having low sensitivity in measuring from low frequencies
The basis of the work of a vibration meter pickup
A vibration pickup is a converter that is used in conjunction with another device to measure vibrations. For example, a seismometer is a type of pickup. This device is a mass, spring, damper that is placed inside a chamber. With this arrangement, the movement of the spring end and the damping end is like the movement of the chamber. In this way, the displacement of the oscillating mass relative to the base can be measured by using a hand (which is attached to the oscillating mass) and a calibrated scale (which is attached to the housing).
Basics of vibration sensors:
A vibration sensor is the first device needed to measure vibrations and a device that senses vibrational motion and converts it into an AC electrical signal proportional to vibrational motion. Contact vibration sensors are classified into 3 groups:
1- Accelerometer
(Accelerometers)
2- Speedometer
(Velocity meters)
3- Displacement meter
(Displacement Probes)
Most vibrometers or vibration meters, or vibration meters, have all three of the above sensors, including vibrometers.
What causes phase distortion in vibration measurement?
This phenomenon becomes important due to the lag time lag between the input and output of the measuring instrument, when the desired vibration is the sum of several simple oscillating vibrations. Each measuring instrument has a time delay from the movement of the object to the sending of the signal. To understand this phenomenon well, pay attention to the opposite figure. It is seen in the upper diagram of the input signal and in the lower diagram of the output signal. The dashed lines represent two simple (harmonic) oscillations with frequencies ω and ω 3, the first of which has a delay of 90 and the second of 180 degrees (shift rate. Time is also different, so the shape of the main signal, which is indicated by dashed lines and is the sum of these two signals, is completely different at the input and output, and we read a different signal from the actual value at the output of the measuring device. Phase distortion is called phase distortion.
Vibration frequency measuring devices
1- Telemetry Folarton single tape or telemeter
( Single reed or Fullarton Tachometer)
2- Multi-band telemeter or frame telemeter
(Multi reed Frahm Tachometer)
3- Strobe scope
(stroboscope)
Note: The more accurate term is Tachometer, not telemeter because many vibrating devices do not have a rotating state.
These tools operate on the principle of resonance in oscillations.
What are the disadvantages of using impact hammer actuators?
Firstly, it can not provide enough energy to generate a signal in an arbitrary frequency range, and secondly, it is difficult to control the direction of the force applied to it.
The electrodynamic actuator has two natural frequencies: one corresponding to the normal frequency of the flexible support and the other corresponding to the normal frequency of the moving part, which may be very large.