Overview
The pen vibrometer, also called the vibrating pen, is designed using the piezoelectric effect of quartz crystal and artificially polarized ceramic (PZT). It is widely used in machinery manufacturing, electric power, metallurgy and other fields.
The vibrating pen adopts an integrated acceleration sensor. The body is compact, light and portable. It is mainly used for quick inspection of motors, fans, pumps, compressors, machine tools, etc., for preventive inspection of mechanical equipment failures; especially suitable for inspection personnel. use.
working principle
The working principle of the pen vibrometer is the same as that of other vibrometers. Today's vibrometers are generally piezoelectric, and there are roughly two types of structures: 1 compression type; 2 shear type.
The principle of the vibrometer is designed using the piezoelectric effect of quartz crystal and artificially polarized ceramic (PZT). When a quartz crystal or an artificially polarized ceramic is subjected to mechanical stress, a charge is generated on the surface thereof, and the magnitude of the charge density formed is strictly linear with the magnitude of the applied mechanical stress. At the same time, the mechanical stress is proportional to the acceleration value under certain sensitive mass. Under certain conditions, the electric charge generated by the piezoelectric crystal is proportional to the perceived acceleration value. The generated charge is output by the charge amplifier and other arithmetic processing. It is the data we need. Q=dij·F=dij·ma where: Q-piezoelectric crystal output charge, dij-piezoelectric crystal second-order piezoelectric Tensor, sensitive mass of m-acceleration, a-accepted vibration acceleration value. The vibrometer piezoelectric accelerometer bears the amount of charge output per unit of vibration acceleration value, and its charge sensitivity is expressed in units of pC/ms-2 or pC/g (1g=9.8ms-2). The vibration accelerometer is essentially equivalent to a charge source and a capacitor. After the equivalent circuit is simplified, the voltage sensitivity of the accelerometer can be converted to Sv=SQ/CaSv-, the voltage sensitivity of the accelerometer, mV. Charge sensitivity of /ms-2SQ-accelerometer, capacitance sensor of pC/ms-2Ca-accelerometer Piezoelectric speed sensor, which adds an integral circuit to the piezoelectric accelerometer by passing an acceleration signal By dividing the product once, you can get the speed value of the vibration!
Instructions
1. Measurement of measuring point of vibration measuring table: Using the vibration measuring table, the bearing and axial end point of the main equipment are tested, and the on-site inspection record table is provided, and each measuring point must correspond to each other.
2. Measurement period: It should be measured once every two weeks after the equipment is overhauled or close to overhaul; once every month during normal operation; if there is a significant change between the measured value and the previous measurement, the test density should be strengthened to Prevent accidents and cause downtime.
3. Basis for determining the measured value: Refer to the international standard ISO2372.
Speed: 600~1200r/min, vibration measurement range: 10~1000Hz. Generally, when the equipment is in normal operation, the detection speed value is in the range of 4.5~11.2mm/s (units above 75kW) for monitoring use. If it exceeds 7.1mm/s, it is necessary to consider major repairs. In addition to considering the motor capacity of the equipment, the determination of this value should also consider the aspects of strong work continuity and high safety and reliability. In short, the vibration meter is used in conjunction with other testing instruments to facilitate analysis of the operating state of the equipment. If the vibration meter is used together with oil quality analyzer, motor fault detector, alignment instrument, etc., it can more accurately judge the operation of the equipment.
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