本文選題：深孔加工 + 顫振��； 參考：《中北大學(xué)》2014年碩士論文

【摘要】：在深孔鉆削加工過程中，一般存在著三種形式的振動：自由振動、強迫振動和自激振動。通過消除外部激振源或其他方法可以抑制甚至消除自由振動和強迫振動，但很難找到有效的方法來抑制自激振動（顫振）的產(chǎn)生。顫振不僅會降低生產(chǎn)效率、減少刀具和機床的使用壽命，而且也會危害操作者的身體健康。所以對顫振的研究具有一定的實際意義。 磁流變液是一種新型的智能材料，它可以在外加磁場作用下發(fā)生磁流變效應(yīng)，實現(xiàn)固液兩態(tài)之間毫秒級的轉(zhuǎn)化：在外加磁場作用下，其粘度、屈服應(yīng)力和剪切模量在毫秒級的單位內(nèi)會急劇增大；外加磁場消失后又能瞬時恢復(fù)至原來的狀態(tài)。因此磁流變液在振動控制方面有著良好的應(yīng)用前景。 針對深孔鉆削加工過程中出現(xiàn)的顫振問題，本文提出利用磁流變液來抑制顫振的發(fā)生。首先分析了金屬切削加工過程中顫振產(chǎn)生的機理，其中再生型顫振被證明是最主要的自激振動機理；并對鉆削加工過程中出現(xiàn)的再生型顫振和振型耦合型顫振進行了分析。通過研究各自的深孔鉆削過程的動力學(xué)模型，找出了它們各自的臨界條件。 其次研究了磁流變液材料的原理、磁流變效應(yīng)的機理和磁流變液減振器的設(shè)計原理，，設(shè)計了應(yīng)用于深孔機床的減振器，計算出減振器模型輸出的阻尼力并得到其應(yīng)用于深孔機床的動力學(xué)模型及動力學(xué)方程。然后，利用Matlab中的Simulink組件對動力學(xué)方程進行了仿真分析，結(jié)果表明減振器對顫振有很好的抑制作用。 最后，提出了基于BP神經(jīng)網(wǎng)絡(luò)PID控制的深孔加工磁流變液減振器控制算法。運用BP神經(jīng)網(wǎng)絡(luò)的在線學(xué)習(xí)能力，實現(xiàn)了PID控制參數(shù)在線最優(yōu)自調(diào)整，使控制系統(tǒng)具有較強的自適應(yīng)能力和魯棒性。
[Abstract]:In the process of deep hole drilling, there are generally three kinds of vibration: free vibration, forced vibration and self-excited vibration. Free vibration and forced vibration can be suppressed or even eliminated by eliminating external excitation sources or other methods, but it is difficult to find effective methods to suppress the generation of self-excited vibration (flutter). Flutter not only reduces production efficiency and service life of cutting tools and machine tools, but also endangers the health of operators. Therefore, the study of flutter has certain practical significance. Magnetorheological fluid (MRF) is a new kind of intelligent material, which can produce magneto-rheological effect under the action of external magnetic field, and realize the conversion of millisecond order between two states of solid and liquid: under the action of external magnetic field, the viscosity of magnetorheological fluid can be obtained. The yield stress and shear modulus increase sharply in the unit of millisecond order, and the applied magnetic field disappears and can return to its original state. Therefore, magnetorheological fluid has a good application prospect in vibration control. Aiming at the flutter problem in the deep hole drilling process, this paper proposes that the magnetorheological fluid can be used to suppress the flutter. Firstly, the mechanism of flutter in metal cutting process is analyzed, among which the regenerative flutter is proved to be the most important self-excited vibration mechanism, and the regenerative flutter and the coupling flutter in the drilling process are analyzed. Their critical conditions are found by studying the dynamic models of their deep hole drilling process. Secondly, the principle of magneto-rheological fluid material, the mechanism of magneto-rheological effect and the design principle of magneto-rheological fluid shock absorber are studied, and the shock absorber used in deep hole machine tool is designed. The damping force output from the damper model is calculated and the dynamic model and dynamic equation applied to the deep hole machine tool are obtained. Then, the dynamic equations are simulated and analyzed by using the Simulink module in Matlab. The results show that the damper has a good effect on the suppression of flutter. At last, the control algorithm of MRF shock absorber for deep hole machining based on BP neural network PID control is proposed. The online learning ability of BP neural network is used to realize the on-line optimal self-adjustment of PID control parameters, which makes the control system more adaptive and robust.
【學(xué)位授予單位】：中北大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TG52;TB535

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