【摘要】：臥式螺旋卸料沉降離心機是一種應(yīng)用廣泛的離心沉降分離設(shè)備,結(jié)構(gòu)上存在螺旋和轉(zhuǎn)鼓兩個轉(zhuǎn)子,由于特殊的雙轉(zhuǎn)子結(jié)構(gòu),振動問題是制約其發(fā)展的主要因素。為此,本文針對某類型的高速臥螺離心機開展了振動測試和數(shù)值模擬計算研究,分析得到了該型離心機主要的振動故障,研究了臥螺離心機雙轉(zhuǎn)子結(jié)構(gòu)的動力學(xué)特性,以期為臥螺離心機的結(jié)構(gòu)設(shè)計提供依據(jù)。本文通過對空載下的某型號臥螺離心機進行振動測試,采用幅頻圖和幅值譜分析其振動特征,結(jié)果表明,由于螺旋轉(zhuǎn)子徑向剛度不對稱,該型臥螺離心機在低轉(zhuǎn)速共振時幅值譜表現(xiàn)出明顯的二倍頻特征。由于二倍頻的影響,臥螺離心機在低轉(zhuǎn)速下發(fā)生倍頻共振,振動劇烈,對機組影響較大,因此設(shè)計過程中應(yīng)盡量提高螺旋轉(zhuǎn)子的對稱性。分別測試了負(fù)載和同步轉(zhuǎn)速下系統(tǒng)的振動,結(jié)果表明負(fù)載后系統(tǒng)振動加劇,共振區(qū)變寬;轉(zhuǎn)速差的存在雖然沒有提高整體振動烈度,但是由于拍振的作用,存在轉(zhuǎn)速差時轉(zhuǎn)子振動的危險性更高。本文基于ANSYS的非線性瞬態(tài)分析,以旋轉(zhuǎn)位移約束模擬轉(zhuǎn)動,建立了非對稱轉(zhuǎn)子的有限元模型,研究了重力作用下非對稱轉(zhuǎn)子的動力學(xué)特性,得到了低速倍頻共振、轉(zhuǎn)子各方向振動相同的結(jié)論。通過對非對稱轉(zhuǎn)子不平衡響應(yīng)特性的研究,結(jié)果表明,相同軸向位置不同相位的加重,轉(zhuǎn)子的振幅和相位響應(yīng)差別較大,傳統(tǒng)的動平衡方法不適用于非對稱轉(zhuǎn)子。為此,研究提出了改進的適用于非對稱轉(zhuǎn)子的動平衡方法。針對臥螺離心機復(fù)雜支撐的超靜定結(jié)構(gòu),本文建立了軸承非線性剛度迭代計算模型,考慮齒輪嚙合剛度、變形阻尼和油膜阻尼,采用實體單元建立螺旋-差速器-轉(zhuǎn)鼓雙轉(zhuǎn)子耦合振動轉(zhuǎn)子動力學(xué)模型。應(yīng)用ANSYS模態(tài)分析分別計算雙轉(zhuǎn)子和單轉(zhuǎn)子臨界轉(zhuǎn)速與主振型,得到了差速器、單轉(zhuǎn)子固有模態(tài)對雙轉(zhuǎn)子固有模態(tài)的作用,并進一步研究了軸承剛度和轉(zhuǎn)子壁厚對轉(zhuǎn)子固有模態(tài)的影響規(guī)律。利用諧響應(yīng)分析分別計算系統(tǒng)在轉(zhuǎn)鼓、螺旋不平衡作用下的動態(tài)響應(yīng),結(jié)果表明,系統(tǒng)對于不同轉(zhuǎn)子相同不平衡量下的振幅和相位響應(yīng)不盡相同,單轉(zhuǎn)子的“重徑積相等,系統(tǒng)不平衡響應(yīng)相同”的準(zhǔn)則并不適用于雙轉(zhuǎn)子。應(yīng)用瞬態(tài)分析計算微速差雙轉(zhuǎn)子的拍振特性,對比雙轉(zhuǎn)子和單轉(zhuǎn)子不平衡時的振動特征,發(fā)現(xiàn)低轉(zhuǎn)速下系統(tǒng)對于各轉(zhuǎn)子不平衡的響應(yīng)互不影響。本文的研究結(jié)果,對臥螺離心機結(jié)構(gòu)的優(yōu)化設(shè)計和高速動平衡具有重要的指導(dǎo)價值,對旋轉(zhuǎn)機械的振動故障診斷和防振設(shè)計具有重要的意義。
[Abstract]:Horizontal screw discharge centrifuge is a widely used centrifuge for settling separation. There are two rotors of screw and drum in the structure. Because of the special double rotor structure, the vibration problem is the main factor that restricts the development of the centrifuge. For this reason, the vibration test and numerical simulation of a certain type of high-speed horizontal centrifuge are carried out in this paper. The main vibration faults of the centrifuge are analyzed, and the dynamic characteristics of the double rotor structure of the horizontal spiral centrifuge are studied. In order to provide the basis for the structure design of the horizontal spiral centrifuge. In this paper, the vibration characteristics of a certain type of horizontal spiral centrifuge under no load are analyzed by amplitude frequency diagram and amplitude spectrum. The results show that the radial stiffness of spiral rotor is not symmetrical. The amplitude spectrum of this type of horizontal spiral centrifuge shows obvious double frequency characteristics at low speed resonance. Because of the influence of double frequency, the double frequency resonance of horizontal spiral centrifuge occurs at low speed, and the vibration is violent, which has a great influence on the unit. Therefore, the symmetry of spiral rotor should be improved in the design process as far as possible. The vibration of the system under the load and the synchronous rotational speed is measured respectively. The results show that the vibration of the system intensifies after the load, and the resonance region becomes wider. The existence of the rotational speed difference does not improve the overall vibration intensity, but because of the action of the beat vibration, The rotor vibration is more dangerous when the speed difference exists. Based on the nonlinear transient analysis of ANSYS, the finite element model of asymmetric rotor is established by using rotating displacement constraint to simulate rotation. The dynamic characteristics of asymmetric rotor under gravity are studied, and the low speed frequency doubling resonance is obtained. The rotor vibration in all directions is the same conclusion. By studying the unbalance response characteristics of asymmetric rotor, the results show that the amplitude and phase response of the rotor vary greatly with the same axial position and different phases, and the traditional dynamic balancing method is not suitable for asymmetric rotor. Therefore, an improved dynamic balancing method for asymmetric rotor is proposed. Aiming at the statically indeterminate structure of complex support of horizontal spiral centrifuge, an iterative calculation model of bearing nonlinear stiffness is established in this paper, in which gear meshing stiffness, deformation damping and oil film damping are considered. The rotor dynamics model of screw-differential-drum-rotor coupling vibration is established by using solid element. The ANSYS modal analysis is used to calculate the critical speed and the main mode of the double rotor and the single rotor respectively, and the effect of the differential mode and the single rotor mode on the natural mode of the double rotor is obtained. The effects of bearing stiffness and rotor wall thickness on the inherent modes of the rotor are further studied. The harmonic response analysis is used to calculate the dynamic response of the system under the action of drum and screw unbalance respectively. The results show that the amplitude and phase response of the system are different for different rotor under the same unbalance, and the "weight diameter product" of the single rotor is equal. The same unbalance response criterion is not applicable to double rotors. Transient analysis is applied to calculate the beat vibration characteristics of two rotors with slight velocity difference, and the vibration characteristics of double rotors and single rotors are compared. It is found that the response of the system to the unbalance of each rotor is not affected at low speed. The results of this paper have important guiding value for the optimum design of horizontal screw centrifuge structure and high-speed dynamic balance, and are of great significance for vibration fault diagnosis and anti-vibration design of rotating machinery.
【學(xué)位授予單位】：天津大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TQ051.84

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