Judging criteria for the performance of ultrasonic cleaning transducers

First, the parameters：

1, mechanical resonance frequency of cleaning transducer ultrasonic transducer
: that is, the operating frequency of the vibration system, the design should be as close as possible to the expected value, and must match the power supply operating point.

2, dynamic resistance of piezoelectric cleaning transducer: the resistance of the series of piezoelectric vibrators, the smaller is the better under the same support conditions. For cleaning or welding vibrators, it is generally between 5 Ω and 20 Ω. If it is too large, there will be problems in the operation of the vibrator or the vibrating system, such as circuit mismatch or conversion efficiency, and short life of the vibrator.

In general, the Qm of the high power ultrasonic cleaning transducer should be between 500 and 1000. If it is too low, the vibrator efficiency is too high, and the power supply cannot be matched. For ultrasonic welding or machining, the Qm value of the vibrator itself is generally around 50-1000, and the whole system is at 1500-3000.

The vibration efficiency is low, but it cannot be too high, because the higher the Qm, the narrower is the working bandwidth, and the power supply is difficult to match, that is, the power supply is difficult to work at the resonance frequency point, and the device cannot work.

4, free capacitance: the capacitance of the piezoelectric device at 1KHZ frequency, this value is consistent with the value measured by the digital capacitance meter. This value subtracts the dynamic capacitor C1 to get the true static capacitance CO, CO = CT-C1. Use CO to balance the inductor with the inductor. in the washing machine Or in the circuit design of the ultrasonic processing machine, correctly balancing the CO can increase the power factor of the power supply. There are two methods for using the inductor balance, parallel tuning and series tuning.

Anti-resonance frequency of 28KHz cleaning transducer: The resonant frequency of the parallel branch of the Yao Dan vibrator. At this frequency, the impedance Zmax of the piezoelectric vibrator is the largest. If the anti-harmonic impedance Zmax is low, the vibrator has a problem.

Second, the graphics

The vibration performance of the ultrasonic cleaner parts transducer can be directly judged by the logarithmic graph, which is relatively intuitive and practical.

1. Under the normal circumstances, the admittance circle and the conductance curve are as shown in the following figure. The admittance circle is a single circle, and the logarithmic coordinates have only a pair of minimum and maximum values.

2.Under the abnormal conditions, the admittance circle and the conductance curve are as shown in the following figure. There are multiple parasitic small circles on the admittance chart. The logarithmic graph has many pairs of minimum and maximum values:

3.In the latter case, the admittance circle and conductance curve of the piezoceramic transducer will be abnormal: