What Is a Vibrograph?

A vibrometer is an instrument used to directly indicate the peak, peak-to-peak, average, or root mean square value of vibration quantities such as displacement, velocity, acceleration, and acceleration derivative. The main parts of this instrument are: integral-differential circuit, amplifier circuit, voltage detector and meter head. The integration and differentiation circuit is used to complete the integration and differentiation operations between the above-mentioned vibration quantities. Generally, integration and differentiation operation amplifiers can be used, and low-pass filters and high-pass filters can be used to complete the integration and differentiation operations. However, care should be taken when using such instruments for their frequency range of application. The vibrometer can only make people obtain the total intensity (vibration level) of the vibration, but cannot obtain other information, so the range of use is limited. ^[1]

Necessity of using vibrometer * All mechanical and electrical problems of various equipment will occur

For the method of vibration measurement, it is required that it does not have any impact on the vibration process being measured. Therefore, if a point away from the measured object can be regarded as stationary

Amplitude : represents the magnitude of the vibration, the severity of damage to the equipment or mechanical components.

The units of amplitude are: displacement value (mm), speed value (mm / sec), acceleration value (g)

Frequency : representative

Vibration Meter Piezoelectric Vibrometer

The characteristics of the piezoelectric vibrometer are high natural frequency, wide measurement frequency range, small volume, light weight, and small impact on the measured object, so it is widely used in measuring vibration acceleration. The internal resistance of the piezoelectric vibration sensor is high, and the cable connected to the amplifier is easy to introduce interference. Therefore, it is desirable to keep the cable as short as possible and to consider shielding. At the same time, place the preamp near the sensor. Amplifiers used to amplify electrical signals generated by piezoelectric sensors are now mostly charge amplifiers. ^[2]

Vibration Meter Mechanical Vibration Meter

It inserts a spring K (or several springs) in the shell, and installs a mass of mass m below the spring. This also constitutes a mechanical resonance system. Normally mechanical resonance systems are damped.

The actual vibration sensor uses a casing as a base and is fixed on the object to be measured. The relative motion between the mass m and the casing is detected by a mechanical, optical, or electrical method. ^[3]

Vibration meter

The table vibrometer will fix the dial indicator on the dial indicator, fix the dial on the bracket isolated from the ventilator, and contact the dial of the dial with the surface of the bearing box or other measurement parts. measuring. This vibrometer does not need to make any other parts, has a simple structure, and can measure vibration in any direction. The disadvantage of the table vibration meter is that the bracket is not easy to isolate from vibration, and the accuracy is poor.

Vibration meter sponge vibrometer

The sponge vibrometer uses a fixing screw to fix the dial sleeve of the dial indicator on the heavy plate, and a sponge ring is set up. Its characteristics are that the p structure is simple, but its accuracy is poor, and it can only measure vertical vibration.

Vibrometer

The hand-held vibrometer will fix a weight with a handle (about 1.5 "-'2g) on the back of the dial indicator. It is simple in structure and can measure vibration in any direction. Rotate speed = 1000 ~ 2000 rpm, the error is not large at 1 minute.