丸鋸への噴流吹きつけによる騒音低減

Abstract

丸鋸は高次の固有振動数の1つと共鳴していわゆる金属音を発するが, 共鳴振動時の鋸身半径方向の振動は鋸外周部へ向うほど強くなり, 歯底線から2 - 3cmの幅で特に強く振動する。このような金属音を除くため回転丸鋸の側面に空気噴流を吹きつけると, 丸鋸の工作性能を損うことなく金属音を抑制することができる。もっとも適当な条件の場合, 音圧レベルで10dB以上, ピーク周波数の成分音を15dB以上減衰させることが可能である。

Circular saw in idling emits sometimes a discrete high frequency noise which is called screaming or whistling, when the saw blade vibrates resonantly in one of its natural modes as a disk. In a rotating saw blade in resonance, the part of 2-3cm width range from the bottom of gullet vibrates especially strong. To reduce such a screaming noise, air jet against the disk surface was attempted. It damped on the saw blade by frictionless force, by which the cutting performance might be expected to be not influenced. With this method, the sound pressure level and the level of peak frequency component was reduced by about 10dB and 15dB or more, respectively, under proper conditions.