动态载荷激励下的床身结构动力学响应

Dynamic Response of NC Machine Tool's Bed which Caused by Dynamic Load

考虑到数控加工系统的振动及噪声问题,建立了数控机床床身的参数化有限元模型,在模态分析基础上计算固有频率与振动幅值。以简谐力作为动态激振载荷,在350-800Hz频率段进行扫频计算,获得了位移—频率和应力—频率曲线,确定了各阶共振频率点的响应幅值,谐振响应结果表明第2阶模态频率对床身的危害性较大。采用Full方法(完全法)对床身进行瞬态动力学分析,计算出了时域下的位移和加速度响应曲线,分析了机床启动阶段冲击载荷对床身的激励影响。在参数化建模基础上实现了床身结构动力学优化,使其动力学性能得到有效改进,有利于数控机床的高速化发展。

In view of the problem of vibration and noise for NC machining system,finite element modeling of NC machine tool＇s bed was set up,and some important natural frequencies and amplitude of the bed were calculated through modal analysis. A harmonic force was used to as simulating load,and displacement- frequency curve and stress- frequency curve between 350 Hz and 800 Hz were acquired based on frequency sweep computing,and then the response amplitude relative to each resonant frequency was confirmed. According to the result of harmonic analysis,the second natural frequency was more harmful to the bed. Transient dynamic analysis of the bed was carried out by Full method,displacement curve and acceleration curve in time domain were calculated,and the influence of impact load on the bed during the process of NC machine tool＇s starting was analysis. Besides,dynamics optimizing of the bed was carried out based on parametric modeling,and dynamic characteristics of the bed was improved effectively,thus then its benefit for NC machine tool＇s development with high- speed.