Research On The Effect Of The Structure Of Tungsten Circular Saw Blades On Noise

Tungsten circular saw blade is a frequently employed cutting to(?)l in the wood-working industry, but it radiates noise as high as 110dB(A) by sound power level when idling or cutting. The noise mainly roots in high-frequency vibration of the circular saw blade, which is more than 1000Hz. So the noise control of the circular saw blade can effectively decrease the noise pollution and protect the health of the operator on the production line.Firstly, this paper designed and trial-produced some kinds of circular saw blades, such as circular saw blades without radial slots and noise-damping slots, with several patterns of radial slots, with several patterns of noise-damping slots, with several patterns of radial slots and noise-damping slots, with different tooth pitch, with different hook angle. By measuring the natural frequencies and idling or cutting noise of circular saw blades, several noise sources and techniques for noise reduction could be studied.The aerodynamic noise is the dominant noise source. When the self-excited vibration of circular saw blade occurs, there will be the resonant noise which is often called whistling noise. The whistling noise during idling is often more intense than during cutting, and may be more 20dB(A) than the aerodynamic noise. The whistling noise shows a directivity different from that of a non-resonant noise. During cutting, the whistling noise may be weakened or eliminated. The main noise source in cutting is the noise from the work piece hit by the teeth of the saw, which concludes stable state pulsed excitation noise, vibration noise, frictional noise and aerodynamic noise.These results of measuring noise of the different blade samples showed that these blade samples with different radial slots all change the high resonant frequencies, and eliminate the whistling noise of high rotational speed. In the rotational speed range in which the saw blades were tested, the saw blades with copper corks at the end of radial slots produced no whistling noise at all, and then can be said to be a stable saw. Making different noise-damping slots like comb over a saw body can give damping capacity to a saw blade. Over the whole range of rotational speed, a saw blade with radial slots and noise-damping slots can eliminate the whistling noise. In cutting, a saw blade with noise-damping slots can reduce the vibration noise. It is proven that the mechanical imbalance can not excite saw resonant vibration. The effect of tooth pitch on aerodynamic noise is that the noise usually increases with tooth pitch increasing, but the trend is getting weak with increase of tooth pitch. The noise in cutting also increases with tooth pitch increasing. The effect of rake angle on aerodynamic noise is that the noise usually increases with decrease of rake angle, but the trend is not prominent. The noise in...