数控机床振动模态分析与薄弱部位辨识方法研究

Research on Vibration Modal Analysis of CNC Machine Tools and Identification of Weak Parts

数控机床在加工过程中的振动会影响加工稳定性和零件成型质量,研究辨识引起较大振动的机床薄弱部位对提高零件加工质量有重要意义。以VMC850E型立式数控加工中心为研究对象,对引起机床振动的薄弱部位开展辨识研究。机床结构的模态参数是机床的固有属性,只与机床本身的结构有关。进行了机床静态下的锤击实验,得到机床结构的模态参数。根据机床结构的模态振型得到模态质量分布矩阵,模态质量越大则对应部件的振动能量越大,该部件越可能是薄弱部件,由此辨识出主轴最有可能是薄弱部件。进一步,针对传统常用模态分析法的缺点,提出了基于机床自身部件运动来激励机床运行的自激励方法,在主轴随机启停的空运行实验中,通过主轴的响应信号辨识出了机床对应阶次的模态,实验结果表明主轴是机床的薄弱部件。

The vibration of CNC machine tools during the machining process will affect the machining stability and the forming quality of the parts.It is of great significance to study and identify the weak parts of the machine tool that cause larger vibrations to improve the machining quality of the parts.Taking the VMC850E vertical CNC machining center as the research object,the identification and research of the weak parts that cause the vibration of the machine tool were carried out.The modal parameters of the machine tool structure were inherent properties of the machine tool,and were only related to the structure of the machine tool itself.The hammering experiment under the static state of the machine tool was carried out,and the modal parameters of the machine tool structure were obtained.The modal mass distribution matrix was obtained according to the modal mode shape of the machine tool structure.The greater the modal mass,the greater the vibration energy of the corresponding component,and the more likely the component was to be a weak component.From this,it was identified that the spindle was most likely to be a weak component.Furthermore,in view of the shortcomings of the traditional common modal analysis method,a selfexcitation method based on the movement of the machine tool′s own components was proposed to stimulate the operation of the machine tool.The experimental results show that the spindle is the weak part of the machine tool.