深孔加工颤振分析及抑振方法的研究

发布时间：2018-05-13 18:42

本文选题：深孔加工 + 颤振　；参考：《中北大学》2014年硕士论文

【摘要】：在深孔钻削加工过程中，一般存在着三种形式的振动：自由振动、强迫振动和自激振动。通过消除外部激振源或其他方法可以抑制甚至消除自由振动和强迫振动，但很难找到有效的方法来抑制自激振动（颤振）的产生。颤振不仅会降低生产效率、减少刀具和机床的使用寿命，而且也会危害操作者的身体健康。所以对颤振的研究具有一定的实际意义。磁流变液是一种新型的智能材料，它可以在外加磁场作用下发生磁流变效应，实现固液两态之间毫秒级的转化：在外加磁场作用下，其粘度、屈服应力和剪切模量在毫秒级的单位内会急剧增大；外加磁场消失后又能瞬时恢复至原来的状态。因此磁流变液在振动控制方面有着良好的应用前景。针对深孔钻削加工过程中出现的颤振问题，本文提出利用磁流变液来抑制颤振的发生。首先分析了金属切削加工过程中颤振产生的机理，其中再生型颤振被证明是最主要的自激振动机理；并对钻削加工过程中出现的再生型颤振和振型耦合型颤振进行了分析。通过研究各自的深孔钻削过程的动力学模型，找出了它们各自的临界条件。其次研究了磁流变液材料的原理、磁流变效应的机理和磁流变液减振器的设计原理，，设计了应用于深孔机床的减振器，计算出减振器模型输出的阻尼力并得到其应用于深孔机床的动力学模型及动力学方程。然后，利用Matlab中的Simulink组件对动力学方程进行了仿真分析，结果表明减振器对颤振有很好的抑制作用。最后，提出了基于BP神经网络PID控制的深孔加工磁流变液减振器控制算法。运用BP神经网络的在线学习能力，实现了PID控制参数在线最优自调整，使控制系统具有较强的自适应能力和鲁棒性。
[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.
【学位授予单位】：中北大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TG52;TB535

【参考文献】