钎焊金刚石锯片振动噪声的理论分析与实验研究

发布时间：2019-07-01 20:17

【摘要】：钎焊金刚石圆锯片具有磨粒出露高度高、磨粒把持强度高、基体强度可靠、操作安全、加工效率高等优点,应用实践也表明,传统的单层电镀及多层烧结金刚石锯片与树脂砂轮片中磨粒与镀层或胎体之间通过机械作用固结,其磨粒把持强度低、容屑空间小,在重负荷高速加工过程中存在磨粒脱落、树脂砂轮片基体崩裂等现象,限制了加工效率和操作安全性。相对于其他类型锯片,钎焊金刚石锯片在使用过程中与工件的相互作用更加激烈,这种相互作用引起的噪声更大、更加尖锐。针对消音圆锯片的研究历史由来已久,但目前针对钎焊金刚石锯片基体的消音研究尚未全面展开。因此,本文针对加工噪声问题进行深入的探索研究,找出影响钎焊金刚石锯片噪声的关键因素,给出可行的减振降噪方案。本文完成的研究工作主要包括:1)通过理想化锯切工况受力模型,研究了锯片不同锯切工况下所受切削力的时频特性,发现锯片所受激励力的能量主要集中在1kHz以下的低频段,高频段为宽频谐波激励,各频段激励的峰值出现在转频的倍频上。2)通过有限元、边界元仿真,研究了普通基体钎焊金刚石锯片的噪声辐射机理,发现其中2.2mm厚的14寸圆锯片的声辐射临界频率至少在4.5kHz以上;临界频率以下,声辐射效率对锯片噪声影响很大;低频段在1kHz和2kHz附近,节圆振型导致声辐射效率出现峰值,高频段4kHz以上密集出现的节圆型振型使声辐射效率显著提高。3)提出消振级和声辐射效率衰减级这两个对比量来代替绝对量,用来评价消音结构的消音特性,同时解决仿真模型中激励力边界条件难以确定的问题。并通过此法,研究了开孔、开缝锯片的消音特性,发现外边缘的直线型切缝是导致锯片6kHz附近高频噪声的不稳定结构;M型、S型缝在4kHz以上有高频噪声消音作用;径向切缝有-5dB左右声辐射效率衰减;圆孔在振级和声辐射效率上对消音作用不明显。4)本文针对几类难以在仿真环境研究的问题进行了定性分析,针对夹层阻尼、蝴蝶纹以及夹盘对声压、声品质的影响进行了实验测量分析。实验验证了本文部分仿真研究,发现宽频激励下,噪声主要出现在仿真中声辐射效率高的频带上;发现夹层阻尼、大型夹盘具有宽频降噪能力,蝴蝶纹能够消除高频尖锐噪声,与仿真的结果较吻合。
[Abstract]:Brazed diamond circular saw blade has the advantages of high particle exposure height, high abrasive particle control strength, reliable matrix strength, safe operation and high processing efficiency. The application practice also shows that the traditional single-layer electroplating and multi-layer sintered diamond saw blade and resin wheel blade are consolidated by mechanical action between abrasive particle and coating or matrix, and the abrasive particle holding strength is low, the chip space is small, and there is wear particle shedding in the process of heavy load high speed machining. Resin grinding wheel matrix cracking and other phenomena limit the processing efficiency and operation safety. Compared with other types of saw blades, the interaction between brazed diamond saw blades and workpiece is more intense, and the noise caused by this interaction is greater and sharper. The research on silencing circular saw blade has a long history, but the silencing research on brazed diamond saw blade matrix has not yet been carried out in an all-round way. Therefore, in this paper, the problem of machining noise is deeply studied, the key factors affecting the noise of brazed diamond saw blade are found out, and a feasible scheme of vibration reduction and noise reduction is given. The research work completed in this paper mainly includes: 1) through idealizing the force model of sawing under different sawing conditions, the time-frequency characteristics of cutting force under different sawing conditions are studied. It is found that the energy of excitation force on saw blade is mainly concentrated in the low frequency band below 1kHz, the high frequency band is broadband harmonic excitation, and the peak value of excitation in each frequency band appears on the frequency doubling of rotating frequency. 2) through finite element and boundary element simulation, The noise radiation mechanism of diamond saw blade brazed by ordinary matrix is studied. It is found that the critical frequency of acoustic radiation of 14 inch circular saw blade with 2.2mm thickness is at least above 4.5kHz. Below the critical frequency, the acoustic radiation efficiency has a great influence on the noise of saw blade. In the low frequency band near 1kHz and 2kHz, the circular mode leads to the peak acoustic radiation efficiency, and the dense circular mode above the 4kHz in the high frequency band improves the acoustic radiation efficiency significantly. 3) two contrast quantities, the damping level and the acoustic radiation efficiency attenuation level, are proposed to replace the absolute quantity to evaluate the silencing characteristics of the silencing structure, and to solve the problem that the boundary conditions of the excitation force in the simulation model are difficult to determine. Through this method, the silencing characteristics of open and slit saw blades are studied, and it is found that the linear slit on the outer edge is the unstable structure of high frequency noise near the saw blade 6kHz, the M type, the S type slit has the high frequency noise silencing effect above the 4kHz, and the radial slit has the attenuation of the left and right acoustic radiation efficiency of-5dB. The silencing effect of circular hole on vibration level and acoustic radiation efficiency is not obvious. 4) in this paper, several kinds of problems which are difficult to be studied in simulation environment are qualitatively analyzed, and the effects of sandwich damping, butterfly grain and chuck on sound pressure and sound quality are measured and analyzed. The experimental results show that under broadband excitation, the noise mainly appears in the frequency band with high acoustic radiation efficiency in the simulation, and it is found that the sandwich damping, the large chuck has the ability of broadband noise reduction, and the butterfly pattern can eliminate the high frequency sharp noise, which is in good agreement with the simulation results.
【学位授予单位】：南京航空航天大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TG717

【参考文献】