本文選題：Al-Si合金 + 去氫��； 參考：《山東大學(xué)》2016年碩士論文

【摘要】：Al-Si合金材料因其質(zhì)量輕、強(qiáng)度高和導(dǎo)熱性、流動(dòng)性好等優(yōu)點(diǎn),廣泛的應(yīng)用于諸多領(lǐng)域。根據(jù)分析,鋁合金中溶解的氣體有85%為氫氣,熔體的“含氣量”可近似等同于“含氫量”。由于液態(tài)Al-Si合金的氫溶解度較高,當(dāng)熔體冷卻至固態(tài)時(shí),氫溶解度將大大降低,從而過飽和的氫將釋放,在鑄件內(nèi)部形成分散性的細(xì)小氣孔,致使鑄件的力學(xué)性能、抗疲勞性能、耐腐蝕性、延展性均大大降低。因此,除氣(去氫)是增強(qiáng)Al-Si合金的綜合機(jī)械性能的主要措施。本文為優(yōu)化精煉品質(zhì),提高氫凈化率,主要內(nèi)容如下：(1)分析了Al-Si合金熔體中氫的動(dòng)力行為。通過在濱州活塞公司進(jìn)行的BH122A牌號的Al-Si合金精煉后回氫規(guī)律測定實(shí)驗(yàn),驗(yàn)證了氬氣攪拌除氣后的回氫規(guī)律。為減少熔體回氫,進(jìn)一步提高氫凈化率,確定了基于超聲振動(dòng)的二次除氣方法；(2)通過對Al-Si合金熔液中聲場規(guī)律的研究,確定了工具桿下方的聲壓場分布場；通過對空化閾值特性的研究,確定了有效空化作用范圍,此外,通過對瞬態(tài)空化與穩(wěn)態(tài)空化規(guī)律的研究,確定了在熔體去氫過程中穩(wěn)態(tài)空化將起到重要作用,為氣泡上浮模型的建立提供了必要條件；(3)氣泡的生長與上浮規(guī)律,是影響Al-Si合金熔體除氣效果的關(guān)鍵因素�；赗ayleigh-Plesset二階微分方程對氣泡生長規(guī)律進(jìn)行了研究�？紤]由于超聲除氣的過程中氣泡將不斷上浮,本文基于Rayleigh-Plesset方程與Stocks模型,建立了氣泡上浮全程氣泡壁運(yùn)動(dòng)的模型；(4)利用Matlab對氣泡上浮全程氣泡壁運(yùn)動(dòng)的模型進(jìn)行了仿真研究：以氣泡的半徑變化倍數(shù)、上升時(shí)間及振蕩劇烈程度(以氣泡半徑最大值與最小值的差值來描述)等為考核數(shù)據(jù),通過不同高低頻施振頻率與施振時(shí)間下與超聲獨(dú)立施振作用下仿真結(jié)果的對比研究結(jié)果表明：協(xié)同振動(dòng)下氣泡上浮時(shí)間可縮短28.8%,振蕩更為劇烈,從機(jī)理上證明了提高去氫效果的有效性；(5)本文以壓電陶瓷超聲換能器為高頻振源,超磁致伸縮換能器為低頻振源,為使GMA振動(dòng)系統(tǒng)在10-50Hz內(nèi)可控,產(chǎn)生穩(wěn)定的正弦波形。本文基于經(jīng)典P-I模型,結(jié)合相角補(bǔ)償模型,建立了動(dòng)態(tài)復(fù)合前饋補(bǔ)償系統(tǒng),相角補(bǔ)償結(jié)合改進(jìn)型P-I模型的控制方法提高了P-I模型的適用頻域,遲滯補(bǔ)償實(shí)驗(yàn)表明該控制方法可有效減小遲滯系統(tǒng)的非線性誤差,但在高頻情況下,模型精度會(huì)受到一定影響。實(shí)驗(yàn)結(jié)果表明,最大誤差容易產(chǎn)生在滯環(huán)的拐點(diǎn)附近,即信號的極值點(diǎn)附近。為Al-Si合金超聲與低頻結(jié)合振動(dòng)除氣,提供了可行的控制方案與理論基礎(chǔ)。本文主要?jiǎng)?chuàng)新點(diǎn)如下：(1)補(bǔ)充以前研究的局限�；赗ayleigh-Plesset方程與Stocks模型,建立了氣泡上浮全程的運(yùn)動(dòng)的模型；(2)利用Matlab進(jìn)行了仿真研究,通過高低頻結(jié)合施振與超聲獨(dú)立施振作用下氣泡的半徑變化倍數(shù),上升時(shí)間,振蕩劇烈程度的對比,確定更有利于氣泡的上浮和振蕩的高低頻振動(dòng)優(yōu)化參數(shù)組合(功率、頻率、作用時(shí)間)；(3)基于經(jīng)典P-I模型,結(jié)合相角補(bǔ)償模型,建立了GMA動(dòng)態(tài)復(fù)合前饋補(bǔ)償系統(tǒng),相角補(bǔ)償結(jié)合改進(jìn)型P-I模型的控制方法提高了P-I模型的適用頻域,有效改善了低頻振動(dòng)的波形。研究結(jié)果的意義：(1)本文研究了Al-Si合金的去氫機(jī)理,提出的聲場作用下的氣泡上浮模型能直觀體現(xiàn)聲波對氣泡的激勵(lì)作用,對于了解聲波除氣的機(jī)理和本質(zhì)有一定的理論意義。(2)本文提出的GMA控制方法,能顯著改善振源波形,為搭建高低頻復(fù)合振動(dòng),提供了有效的控制方法,具有一定的應(yīng)用意義。
[Abstract]:Al-Si alloy material is widely used in many fields because of its light quality, high strength, good thermal conductivity and good fluidity. According to analysis, 85% of the dissolved gas in aluminum alloy is hydrogen, and the "gas content" of the melt can be approximately equal to "hydrogen content". Because of the high hydrogen solubility of liquid Al-Si alloy, when the melt is cooled to solid, hydrogen is used. The solubility will be greatly reduced, thus the supersaturated hydrogen will be released and the dispersed small pores are formed inside the castings, which greatly reduce the mechanical properties, fatigue resistance, corrosion resistance and ductility of the castings. Therefore, degassing (dehydrogenation) is the main measure to enhance the comprehensive mechanical properties of Al-Si alloys. This paper is to optimize the refining quality and improve the hydrogen. The main contents are as follows: (1) the dynamic behavior of hydrogen in Al-Si alloy melts was analyzed. The law of hydrogen recovery after argon stirring was verified by the test of the recovery of hydrogen after refining the BH122A grade of Al-Si alloy in the Piston Corp of Binzhou. The two degassing method is moved; (2) the distribution field of sound pressure field under the tool bar is determined by the study of the sound field law in the molten liquid of Al-Si alloy. The effective cavitation range is determined by the study of the characteristics of the cavitation threshold. In addition, through the study of the law of transient cavitation and steady cavitation, the steady state in the process of dehydrogenation of the melt is determined. Cavitation will play an important role and provide necessary conditions for the establishment of bubble floating model. (3) the growth and floating law of bubbles are the key factors affecting the degassing effect of Al-Si alloy melt. Based on the two order differential equation of the bubble, the bubble growth law is studied. On the basis of the Rayleigh-Plesset equation and the Stocks model, the model of bubble wall motion is established in this paper. (4) a simulation study of the bubble wall motion model by using Matlab is carried out by using the radius of the bubble radius, the rise time and the intensity of vibration (the maximum and the minimum of the bubble radius). Compared with the simulation results under the action of different high frequency vibration frequency and vibration time and ultrasonic independent vibration, the results show that the floating time of bubbles can be shortened by 28.8% and the oscillation is more intense under the cooperative vibration. The effectiveness of improving the dehydrogenation effect is proved in mechanism. (5) this paper is based on the piezoelectricity. The ceramic ultrasonic transducer is a high frequency oscillator, and the super magnetostrictive transducer is a low frequency oscillator. In order to make the GMA vibration system controllable in the 10-50Hz and produce a stable sinusoidal waveform. Based on the classic P-I model and the phase angle compensation model, a dynamic compound feedforward compensation system is established. The phase angle compensation and the improved P-I model are improved. The P-I model is applied to the frequency domain and the hysteresis compensation experiment shows that the control method can effectively reduce the nonlinear error of the hysteresis system, but the model accuracy will be affected by the high frequency. The experimental results show that the maximum error is easily produced near the turning point of the hysteresis loop, that is, near the extreme point of the signal. It is the combination of the ultrasonic and low frequency of the Al-Si alloy. Vibration degassing provides a feasible control scheme and theoretical basis. The main innovation points of this paper are as follows: (1) supplement the limitations of previous studies. Based on the Rayleigh-Plesset equation and Stocks model, a model of the movement of the whole process of bubble floating is established. (2) the simulation study is carried out by using Matlab, and the combined vibration and ultrasonic vibration of the high and low frequencies are used for the independent vibration of vibration. On the basis of the classical P-I model and the phase angle compensation model, a GMA dynamic compound feedforward compensation system is established based on the classical P-I model and the phase angle compensation mode, and the phase angle compensation combination is combined. The control method of the improved P-I model improves the applicable frequency domain of the P-I model and effectively improves the waveform of the low frequency vibration. The significance of the research results is as follows: (1) the dehydrogenation mechanism of Al-Si alloy is studied in this paper. The bubble floating model under the action of sound field can directly reflect the excitation effect of sound waves on the bubble and the mechanism of understanding the acoustic degassing of sound waves. And the essence has some theoretical significance. (2) the GMA control method proposed in this paper can significantly improve the waveform of the vibration source. It provides an effective control method for building high frequency complex vibration. It has some practical significance.
【學(xué)位授予單位】：山東大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2016
【分類號】：TG292

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1 肖博涵;高低頻協(xié)同振動(dòng)下Al-Si合金熔液去氫機(jī)理與振源控制研究[D];山東大學(xué);2016年

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本文編號：2030022