【摘要】：高鎢合金憑借高強(qiáng)度、耐高溫等性質(zhì)被廣泛應(yīng)用于航空航天等領(lǐng)域中,其中許多零件中包含散熱、通氣等作用的微小孔,這些微小孔的加工若利用傳統(tǒng)方式則存在著很多困難,而電火花加工借助自身的諸多優(yōu)點(diǎn)提供了一種有效的加工方法。但是在電加工中也存在著電極損耗大、加工效率低、加工效果差等問(wèn)題,為此針對(duì)鎢含量高達(dá)90%的銅鎢合金(CuW90)進(jìn)行了加工工藝及穿透檢測(cè)等方面的研究。采用單因素實(shí)驗(yàn)和正交試驗(yàn)相結(jié)合的方案,使用直徑為0.5 mm的管電極對(duì)CuW90微小孔電火花加工進(jìn)行了一系列的基礎(chǔ)實(shí)驗(yàn)研究。首先對(duì)電源電容、電流、伺服參考電壓、伺服速度、占空比等實(shí)驗(yàn)參數(shù)進(jìn)行了單因素實(shí)驗(yàn)研究,分析了使用電火花油和去離子水作為工作液時(shí)電極損耗和加工時(shí)間不同的原因;之后選用L16(45)正交表對(duì)所研究的5個(gè)參數(shù)進(jìn)行了正交試驗(yàn),最終以電極損耗和加工時(shí)間為目標(biāo)得到了微小孔加工的最優(yōu)參數(shù)組合,綜合優(yōu)化幅度達(dá)73%。針對(duì)CuW90的特殊結(jié)構(gòu),對(duì)其物理模型進(jìn)行了分析比較,并計(jì)算了密度、比熱容、熱導(dǎo)率和熱膨脹系數(shù)等性能參數(shù)的理論值,從理論上分析了在電火花加工中電極損耗大的原因。對(duì)旋轉(zhuǎn)內(nèi)沖液加工間隙流場(chǎng)進(jìn)行了仿真分析,利用不同工作液流場(chǎng)結(jié)構(gòu)特點(diǎn)對(duì)不同加工階段流速和壓力的分布進(jìn)行了分析比較,探討了柱狀殘留的成因,從理論方面研究了不同深度時(shí)的加工特點(diǎn),解釋了使用不同工作液時(shí)電極形狀發(fā)生變化的原因。為實(shí)現(xiàn)難加工材料的盲孔加工,利用神經(jīng)網(wǎng)絡(luò)法對(duì)不同參數(shù)下的加工速率進(jìn)行預(yù)測(cè),分析了微小孔加工時(shí)有效放電次數(shù)和工件材料蝕除量的對(duì)應(yīng)關(guān)系,搭建了基于平均電壓檢測(cè)法的檢測(cè)電路,利用STM32F103ZET6芯片對(duì)所采集電壓進(jìn)行了比較判斷,通過(guò)對(duì)數(shù)碼管的直接驅(qū)動(dòng)實(shí)現(xiàn)了加工深度的實(shí)時(shí)顯示,最終所加工盲孔的平均誤差為3.9%。以管電極加工時(shí)穿透前后電壓波形的獨(dú)特變化趨勢(shì)為依據(jù),實(shí)現(xiàn)了最小出口距離為0.7 mm的通孔加工。對(duì)穿透前后柱狀殘留的影響進(jìn)行了理論分析與驗(yàn)證,最終證實(shí)了穿透檢測(cè)判據(jù)的可靠性。
[Abstract]:High tungsten alloy has been widely used in aerospace and other fields because of its high strength, high temperature resistance and other properties. Many of the parts contain micropores such as heat dissipation, ventilation and so on. There are many difficulties in the processing of these micropores by using the traditional method. With the help of many advantages of EDM, EDM provides an effective machining method. However, there are also some problems in electrical machining, such as large electrode loss, low machining efficiency and poor processing effect. Therefore, the processing technology and penetration detection of copper-tungsten alloy (CuW90) with tungsten content of up to 90% have been studied. A series of basic experiments on CuW90 microhole EDM were carried out by using a tube electrode with diameter of 0.5 mm. Firstly, the single factor experimental study on the experimental parameters such as power capacitance, current, servo reference voltage, servo speed and duty cycle is carried out, and the reasons for the different electrode loss and processing time when EDM oil and deionized water are used as working liquid are analyzed. Then the L16 (45) orthogonal table was selected to carry out orthogonal experiments on the five parameters studied. Finally, the optimal parameter combination of micro hole machining was obtained with the goal of electrode loss and processing time, and the comprehensive optimization range was 73%. According to the special structure of CuW90, the physical models are analyzed and compared, and the theoretical values of performance parameters such as density, specific heat capacity, thermal conductivity and thermal expansion coefficient are calculated, and the reasons for the high electrode loss in EDM are analyzed theoretically. The flow field in the clearance of rotating internal flushing fluid is simulated and analyzed, and the distribution of velocity and pressure in different processing stages is analyzed and compared by using the structural characteristics of different working fluid flow fields, and the causes of cylindrical residue are discussed. The machining characteristics of different depths are studied theoretically, and the reasons for the change of electrode shape when different working fluids are used are explained. In order to realize the blind hole machining of refractory materials, the processing rate under different parameters is predicted by neural network method, and the corresponding relationship between the number of effective discharge and the amount of material erosion in micro hole machining is analyzed. The detection circuit based on average voltage detection method is built, the collected voltage is compared and judged by STM32F103ZET6 chip, and the real-time display of machining depth is realized by driving the digital tube directly. The average error of the blind hole is 3.9%. Based on the unique change trend of voltage waveform before and after penetration of tube electrode, the through hole machining with minimum outlet distance of 0.7 mm is realized. The influence of cylindrical residue before and after penetration is analyzed and verified theoretically, and the reliability of penetration detection criterion is finally verified.
【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TG661

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