本文選題：微小孔　切入點(diǎn)：電火花　出處：《哈爾濱工業(yè)大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：隨著微機(jī)電系統(tǒng)的不斷發(fā)展,機(jī)電產(chǎn)品日趨復(fù)雜化、精密化和高性能化,在航空航天、醫(yī)療設(shè)備、電子工業(yè)和國防裝備等領(lǐng)域小孔結(jié)構(gòu)的應(yīng)用日益增多,且廣泛采用高性能材料,這使得微小孔的加工面臨極大的挑戰(zhàn)。電火花加工(EDM)作為一種微小孔加工的常用方法,傳統(tǒng)上多采用液體工作介質(zhì),加工穩(wěn)定性好,但電極損耗偏大。國枝正典等學(xué)者用壓縮氣體作為工作介質(zhì),創(chuàng)造性的提出了氣中電火花加工,顯著降低了電極損耗,甚至出現(xiàn)了負(fù)損耗。由于氣體中放電間隙小,存在加工穩(wěn)定性差,效率低等問題。本文綜合液體和氣體介質(zhì)的特點(diǎn),研究不同氣液混合比下電火花加工的特點(diǎn),以期獲得更快的加工速度和更低的電極損耗。從氣體和液體的放電擊穿特性入手,分別分析了以氣相為主相和以液相為主相的兩相介質(zhì)的放電特性。根據(jù)氣液兩相介質(zhì)電火花微小孔加工工藝實(shí)驗(yàn)的需求,搭建了加工平臺,可以提供不同去離子水和空氣體積比的工作介質(zhì)。最終選用去離子水,去離子水體積比10%的霧以及去離子水體積比90%的氣泡水作為工作介質(zhì)。為進(jìn)一步分析工作液供給系統(tǒng)的沖液效果,以實(shí)際加工參數(shù)為邊界條件,對放電間隙流場進(jìn)行了仿真,證明放電加工在兩相介質(zhì)中進(jìn)行。以加工時間、電極損耗和小孔質(zhì)量為評價(jià)指標(biāo),通過實(shí)驗(yàn)研究了電容、充電電流和伺服參考電壓對電火花微小孔加工的影響。為了對不同介質(zhì)進(jìn)行合理的比較,設(shè)計(jì)了正交試驗(yàn),分析各因素的影響程度,探求各介質(zhì)中最優(yōu)的參數(shù)組合。采用定加工時間和定進(jìn)給深度的方式,探討了不同介質(zhì)中加工速度和電極損耗與加工深度的關(guān)系。相比去離子水,霧中電極損耗低,最多降低27%,氣泡水中加工時間短,最多縮短17%,去離子水中孔錐度小。針對氣液兩相介質(zhì)電火花微小孔加工的特點(diǎn)和機(jī)床控制系統(tǒng)本身的不足,引入PID控制對機(jī)床的伺服控制系統(tǒng)進(jìn)行了改進(jìn)。通過工藝實(shí)驗(yàn),驗(yàn)證了PID控制的有效性。針對PID控制的不足,引入模糊控制,對PID參數(shù)進(jìn)行在線整定。通過實(shí)驗(yàn),與原系統(tǒng)相比,加工時間最多可縮短38%,取得了較好的加工效果。
[Abstract]:With the continuous development of MEMS, electromechanical products are becoming more and more complex, precision and high performance. The applications of orifice structure in aerospace, medical equipment, electronic industry and national defense equipment are increasing day by day. The high performance material is widely used, which makes the machining of micro hole face great challenge. As a common method of micro hole machining, EDM has traditionally used liquid working medium, so it has good processing stability. However, the electrode loss is on the high side. By using compressed gas as the working medium, some scholars creatively proposed EDM in gas, which significantly reduces the electrode loss and even results in negative loss. Because of the small discharge gap in the gas, There are some problems such as poor processing stability and low efficiency. In this paper, the characteristics of EDM under different gas-liquid mixing ratios are studied by synthesizing the characteristics of liquid and gas media. In order to obtain faster processing speed and lower electrode loss, starting with the breakdown characteristics of gas and liquid discharge, The discharge characteristics of two-phase dielectric with gas-phase and liquid-phase are analyzed, and the machining platform is built according to the requirement of the experiment of gas-liquid two-phase dielectric EDM micro-hole machining. Can provide different deionized water and air volume ratio of the working medium. Fog with deionized water volume ratio 10% and bubble water with deionized water volume ratio 90% are used as working media. In order to further analyze the efflux effect of working fluid supply system, the discharge gap flow field is simulated under the boundary condition of actual machining parameters. It is proved that the electric discharge machining is carried out in two phase medium. The capacitance is studied experimentally by taking the processing time, electrode loss and hole quality as the evaluation indexes. The effect of charging current and servo reference voltage on EDM. In order to compare different media reasonably, orthogonal test was designed to analyze the influence of various factors. The optimum parameter combination in each medium is explored. The relationship between machining speed and electrode loss and machining depth in different media is discussed by means of fixed processing time and fixed feed depth. Compared with deionized water, the electrode loss in fog is lower than that in deionized water. The maximum reduction is 27%, the processing time of bubble water is short, the maximum is 17% shorter, and the hole taper in deionized water is small. In view of the characteristics of micro-hole machining of gas-liquid two-phase dielectric EDM and the deficiency of the machine tool control system itself, The PID control is introduced to improve the servo control system of machine tools. The effectiveness of PID control is verified by technological experiments. In view of the deficiency of PID control, fuzzy control is introduced to set the parameters of PID online. Compared with the original system, the processing time can be shortened by 38%, and good processing effect has been achieved.
【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TG661;TH-39
，

本文編號：1564523