基于有限元法的数控车床主轴系统频率可靠性分析

基于有限元法参数化建立主轴系统三维有限元模型,将轴承简化为弹性支撑.考虑皮带轮和卡盘的影响,对整个主轴系统进行模态分析,得到主轴系统的前八阶固有频率及固有振型.进行临界转速分析,将工作转速与非零最低阶频率对应的转速进行比较,验证主轴设计的合理性.利用ISIGHT集成ANSYS进行正交试验设计并计算非零最低阶固有频率,将有公差范围要求的轴段的直径和长度以及基本物理参数作为随机变量,采用BP神经网络拟合主轴系统非零最低阶固有频率与随机变量之间的关系.利用一次二阶矩法计算主轴系统在特定转速下的可靠度并求解各随机参数的可靠性灵敏度.

FEM-based Frequency Reliability Analysis of Spindle System of CNC Lathes

Based on the finite element method， we created a parametric three-dimension finite element model for spindle system and simplified the bearing as elastic support. Taken pulley and chuck into consideration， modal analysis of the entire system was conducted， thus the natural frequencies of the first eight vibrations and the corresponding spindle vibration modes were acquired. Critical speed of rotation was analyzed. We compared the working speed with rotation speed of the lowest non-zero set of frequency， hereby the rationality of design was verified. The ISIGHT integrated with ANSYS was used in designing orthogonal experiment and in calculating the lowest non-zero set of frequency. Diameters and length with tolerance requirements， and basic physical parameters considered as random variables， the BP neural network fitting method was used to get the relationship between the lowest non-zero set of frequency and random variables. The first order second moment (FOSM) method was used to calculate the spindle system reliability with specific rotation speed and reliability sensitivity of random variables.