【作者】 郭晓磊；

【导师】 曹平祥；

【作者基本信息】 南京林业大学 ， 木材科学与技术， 2006， 硕士

【摘要】 硬质合金圆锯片(以下简称圆锯片)是木材加工企业常用刀具之一，然而在圆锯片空载或负载状态下发出的噪声可高达110dB(A)噪声声功率级。圆锯片噪声的主要来源是圆锯片在空载或负载状态下的高频噪声，其频率一般在1000Hz以上。对圆锯片进行噪声控制可以有效降低圆锯机的空载和负载噪声，减少车问里的噪声污染，保护操作人员的身心健康。 本文首先设计、试制了几种不同结构的圆锯片，如无径向槽和消音细缝的圆锯片、有径向槽或消音细缝的圆锯片、有径向槽和消音细缝的圆锯片及几种齿距和锯齿前角的圆锯片。通过圆锯片固有频率和噪声声压级的测试，研究分析圆锯片各种噪声源的形成机理，及其噪声源控制方法和途径。 空气动力性噪声是圆锯片最主要的噪声。当圆锯片旋转产生自激振动时，会有持续的共振噪声，通常被称之为“啸声”。当空载圆锯片产生“啸声”时，其空载噪声比负载噪声还要刺耳，且最大可超出空气动力性噪声达20dB(A)。“啸声”具有一定的指向性，在负载状态下，可以减弱或消除这种噪声。负载噪声主要是由圆锯片击打工件，圆锯片与工件相互作用产生的稳态脉冲激励噪声、振动噪声、摩擦噪声和空气动力性噪声组成。 不同结构的圆锯片噪声测试结果表明：不同结构的径向槽均可改变圆锯片高频共振频率，消除圆锯片较高转速下的“啸声”；而径向槽底部圆孔塞有金属铜的圆锯片，可以消除所有测试转速范围的“啸声”，并且噪声控制稳定；在基体内部加工不同结构消音细缝可以增大系统阻尼，当径向槽与消音细缝组合后，其可以消除整个测试转速范围内的“啸声”，且消音细缝有助于降低负载状态下的振动噪声。圆锯片动态不平衡不会导致产生共振噪声。齿距对空气动力性噪声的影响是，随着齿距的增大，噪声也随之增大，但这种趋势是在不断减弱；而对负载噪声的影响也是随着齿距的增大，噪声也随之增大。锯齿前角对空气动力性噪声的影响是，随着前角的减小，噪声随之增大，但这种趋势并不十分明显；而对负载噪声的影响也是随着前角的减小，噪声随之增大。转速对空气动力性噪声的影响要远大于对负载状态下稳态脉冲激励噪声、振动噪声和摩擦噪声的影响。更多还原

【Abstract】 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更多还原