No.7（2004）7.Reduction of the Noise arising from an Ultrasonic Cleaner with Dynamic Absorber

Norichika HASEGAWA, Koichi KANDA, Osamu NAKADA, Asako HIRAMA, Shoichi TAKADA

We have tried to reduce the noise arising from the resonance of washing liquids (spurious resonance) using a dynamic absorber for ultrasonic cleaners which utilize cavitations. First, in order to investigate the effects of a dynamic absorber, we simulated the vibration of the dynamic system with a mass-spring model. According to the results of the investigation, we have found the following facts.

1. The dynamic absorber of which the mass had a few decade grams have been effective on washing liquids of which the mass had a few decade kilograms.
2. The tolerance of the difference between the resonance frequency of the dynamic absorber system and that of the washing liquid system was a few hundred Hz.
3. A loss factor of 0.1 of dynamic absorber has been enough to reduce the noise arising from the spurious resonance.

Secondly, we prepared a damped steel beam as the dynamic absorber and equipped them on the vessel wall of the cleaner taking into account the vibration mode. According to the results of the experiment, the amount of the noise reduction reached 30dB up to 40dB.

Keywords
Ultrasonic cleaner, Spurious resonance, Dynamic absorber, Damped steel beam, Loss factor

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