考虑过程阻尼的铣削稳定性建模及仿真分析

发布时间：2018-08-06 18:01

【摘要】：切削过程中过程阻尼的存在导致低速区临界切削深度显著增加。建立考虑过程阻尼影响的铣削稳定性模型,对铣削过程稳定性叶瓣图进行准确预测,对于实现诸如钛合金、镍基合金等无法采用高速加工的航空难加工材料的高效切削至关重要。本论文拟以铣削过程中产生的过程阻尼为研究对象,首先进行过程阻尼建模研究并分析刀具几何参数及加工条件等对过程阻尼的影响;其次建立了考虑过程阻尼影响的铣削稳定性模型,采用解析法及全离散法对铣削稳定性模型进行了求解;最后通过颤振稳定域试验验证了铣削稳定性模型及其求解方法的正确性。在过程阻尼建模方面:首先描述了过程阻尼的产生机理,指出过程阻尼是在切削过程中刀具后刀面与已加工表面振纹之间的挤压所产生的,在此基础上分别通过解析法与数值法计算压痕面积并获得了过程阻尼的解析表达式;其次,采用能量等效法对过程阻尼系数进行辨识,通过将压痕力所消耗的能量等效为粘性阻尼所消耗的能量,求出了压痕力系数;最后,通过数值仿真,分析了刀具几何参数及切削条件等对过程阻尼系数的影响。在考虑过程阻尼影响的铣削稳定性建模与解析求解方面:首先,将铣削系统简化为二自由度振动系统,基于过程阻尼力模型和再生切削力模型,建立其动力学微分方程;其次,将动态切削力进行傅里叶级数展开并只保留一次谐波,由特征方程的特征根来求解临界轴向切削深度,进而获得稳定性叶瓣图;最后通过切削颤振试验验证模型及其解析求解方法的正确性,通过仿真来分析铣削加工工艺参数对稳定性叶瓣图的影响。针对经典解析方法无法预测浅径向浸入铣削时存在的附加稳定性叶瓣的局限性,通过借鉴用于求解未考虑过程阻尼影响铣削稳定性的全离散方法,实现了考虑过程阻尼影响的铣削稳定性模型求解,并评估了算法的收敛性,最后通过切削颤振试验验证了求解方法的正确性。
[Abstract]:The existence of process damping in the cutting process leads to a significant increase in critical cutting depth in the low speed region. The stability model of milling considering the influence of process damping is established to predict accurately the stability of vanes in milling process. High-efficiency cutting of non-machined aeronautical materials such as nickel-based alloys is very important. In this paper, the process damping produced in milling process is taken as the research object. Firstly, the modeling of process damping is carried out and the effects of tool geometry parameters and machining conditions on the process damping are analyzed. Secondly, the stability model of milling considering the influence of process damping is established, and the stability model of milling is solved by analytic method and full discrete method. Finally, the validity of milling stability model and its solution are verified by flutter stability region test. In the modeling of process damping: firstly, the mechanism of process damping is described, and it is pointed out that the process damping is produced by extrusion between the tool surface and the machined surface in the cutting process. On this basis, the indentation area is calculated by the analytical method and the numerical method, and the analytical expression of the process damping is obtained. Secondly, the damping coefficient of the process is identified by the energy equivalent method. By equivalent the energy consumed by indentation force to the energy consumed by viscous damping, the indentation force coefficient is obtained. Finally, through numerical simulation, the effects of tool geometry parameters and cutting conditions on the damping coefficient of the process are analyzed. The modeling and analytical solution of milling stability considering the influence of process damping are as follows: firstly, the milling system is simplified as a two-degree-of-freedom vibration system, and its dynamic differential equation is established based on the process damping force model and the regenerative cutting force model. The dynamic cutting force is expanded by Fourier series and only the first harmonic is retained. The critical axial cutting depth is solved by the characteristic root of the characteristic equation, and the stable leaf lobe diagram is obtained. Finally, the correctness of the model and its analytical solution are verified by cutting flutter test, and the influence of milling process parameters on the stable vanes diagram is analyzed by simulation. In view of the limitation of the classical analytical method which can not predict the additional stable flaps in shallow radial immersion milling, the full discrete method is used to solve the problem that the process damping is not considered to affect the milling stability. The stability model of milling considering the influence of process damping is solved, and the convergence of the algorithm is evaluated. Finally, the correctness of the method is verified by cutting flutter test.
【学位授予单位】：湖南工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG54

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