大行程机床动态特性灵敏度分析及实验研究

Dynamic Characteristics Sensitivity Analysis and Experimental Research of Large Stroke Machine Tools

为大行程机床动态特性随加工区间、姿态的不同将发生很大的改变,基于单一状态下的动力学模型/方程不能描述其全加工空间内动态特性的变化规律。文章以动梁式龙门机床为例,采用集总参数法建立了机床的动力学模型,并推导了其变系数线性动力学方程。采用灵敏度分析法研究了机床第1阶固有频率对于位置参数的敏感程度及变化规律。结果表明:系统第1阶特征值对于位置参数z的灵敏度大于对于位置参数x的灵敏度,系统第1阶固有频率主要由位置参数z决定,且变化幅度可达40%以上。最后通过实验测试验证了模型的准确性。

The dynamic characteristics of large stroke machine tools will highly change when its machining space and cutting pose vary. So that the dynamic model/equation based on single state cannot describe the variation of dynamic characteristics in its whole machining space. This paper take a gantry beam-moving machine tool as an example to demonstrate the method of lumped parameter dynamic model of machine tool, and the coefficient-varying linear dynamic equation is derived. The sensitivity analyzing method is used to studied the sensitivity and variation rules of the first natural frequencies with respect to position parameters. The results show that the sensitivities of the first natural frequencies with respect to position parameter z is greater than that with respect to position parameter x . The first natural frequencies are dominated by position parameter z , and the variation magnitude can be up to above 40%. At last the model accuracy is validated by experimental measurement.