数控机床运行激励实验模态分析

Movement exciting-based experimental modal analysis of NC machine tools

针对影响加工效率和加工表面质量的数控机床结构动态特性问题,提出一种新的实验模态分析方法.该方法以数控机床自身运动产生的振动为激励源,通过控制运动部件以特定方式空运行,激励起结构的有效振动响应,并结合基于响应信号的模态参数识别方法获得结构的动态特性参数.针对参数识别中的伪模态问题,综合运用识别结果预处理方法和模态稳定性原理,有效去除了识别结果中的伪模态,最终得到影响机床加工的3阶低频模态频率和阻尼比.所得结果与传统实验模态分析结果有较好的一致性.该方法可用于大型重型难激励数控机床的结构动态特性研究.

Dynamic performance of numerical control （NC） machine tools affect machining efficiency and finished surface quality. A new experimental modal analysis was proposed to acquire the dynamic parameters of machine tools. In the modal analysis, the machine tool＇s movement was vibration excit ing source. By controlling the movement of movable parts, effective structural vibration response was excited. And, combining response-only modal parameter identification, the structural dynamic per formance parameters of machine tool were achieved. For pseudo-mode existing in parameter identifica tion, the integration of preprocessing method and modal stability principle was applied, and pseudomode was effectively eliminated from identification results. Then, 3-order modal frequency and damping ratio in low-frequency, which mainly affect machining, were obtained. The results of the experimental modal analysis and those of traditional are in good agreement. The presented method can be used to research structural dynamic performance of large or heavy-duty machine tools, which are diffi- cult to be excited.