發(fā)布時(shí)間：2019-07-01 20:17

【摘要】：釬焊金剛石圓鋸片具有磨粒出露高度高、磨粒把持強(qiáng)度高、基體強(qiáng)度可靠、操作安全、加工效率高等優(yōu)點(diǎn),應(yīng)用實(shí)踐也表明,傳統(tǒng)的單層電鍍及多層燒結(jié)金剛石鋸片與樹脂砂輪片中磨粒與鍍層或胎體之間通過機(jī)械作用固結(jié),其磨粒把持強(qiáng)度低、容屑空間小,在重負(fù)荷高速加工過程中存在磨粒脫落、樹脂砂輪片基體崩裂等現(xiàn)象,限制了加工效率和操作安全性。相對(duì)于其他類型鋸片,釬焊金剛石鋸片在使用過程中與工件的相互作用更加激烈,這種相互作用引起的噪聲更大、更加尖銳。針對(duì)消音圓鋸片的研究歷史由來已久,但目前針對(duì)釬焊金剛石鋸片基體的消音研究尚未全面展開。因此,本文針對(duì)加工噪聲問題進(jìn)行深入的探索研究,找出影響釬焊金剛石鋸片噪聲的關(guān)鍵因素,給出可行的減振降噪方案。本文完成的研究工作主要包括:1)通過理想化鋸切工況受力模型,研究了鋸片不同鋸切工況下所受切削力的時(shí)頻特性,發(fā)現(xiàn)鋸片所受激勵(lì)力的能量主要集中在1kHz以下的低頻段,高頻段為寬頻諧波激勵(lì),各頻段激勵(lì)的峰值出現(xiàn)在轉(zhuǎn)頻的倍頻上。2)通過有限元、邊界元仿真,研究了普通基體釬焊金剛石鋸片的噪聲輻射機(jī)理,發(fā)現(xiàn)其中2.2mm厚的14寸圓鋸片的聲輻射臨界頻率至少在4.5kHz以上;臨界頻率以下,聲輻射效率對(duì)鋸片噪聲影響很大;低頻段在1kHz和2kHz附近,節(jié)圓振型導(dǎo)致聲輻射效率出現(xiàn)峰值,高頻段4kHz以上密集出現(xiàn)的節(jié)圓型振型使聲輻射效率顯著提高。3)提出消振級(jí)和聲輻射效率衰減級(jí)這兩個(gè)對(duì)比量來代替絕對(duì)量,用來評(píng)價(jià)消音結(jié)構(gòu)的消音特性,同時(shí)解決仿真模型中激勵(lì)力邊界條件難以確定的問題。并通過此法,研究了開孔、開縫鋸片的消音特性,發(fā)現(xiàn)外邊緣的直線型切縫是導(dǎo)致鋸片6kHz附近高頻噪聲的不穩(wěn)定結(jié)構(gòu);M型、S型縫在4kHz以上有高頻噪聲消音作用;徑向切縫有-5dB左右聲輻射效率衰減;圓孔在振級(jí)和聲輻射效率上對(duì)消音作用不明顯。4)本文針對(duì)幾類難以在仿真環(huán)境研究的問題進(jìn)行了定性分析,針對(duì)夾層阻尼、蝴蝶紋以及夾盤對(duì)聲壓、聲品質(zhì)的影響進(jìn)行了實(shí)驗(yàn)測(cè)量分析。實(shí)驗(yàn)驗(yàn)證了本文部分仿真研究,發(fā)現(xiàn)寬頻激勵(lì)下,噪聲主要出現(xiàn)在仿真中聲輻射效率高的頻帶上;發(fā)現(xiàn)夾層阻尼、大型夾盤具有寬頻降噪能力,蝴蝶紋能夠消除高頻尖銳噪聲,與仿真的結(jié)果較吻合。
[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.
【學(xué)位授予單位】：南京航空航天大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2016
【分類號(hào)】：TG717

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