正交车铣铝合金薄壁回转体振动信号的试验分析

在MAZAK机床上正交车铣薄壁铝合金试件，压电加速度传感器安装在内壁上，通过PCI-1712高速数据采集卡采集薄壁的振动信号。利用MATLAB强大的信号处理功能对采集的加速度信号进行分析，振动信号的时域标识了振动幅值大小，功率谱显示了薄壁振动信号的频率构成和能量分布。分析了自激振动的频率随刀具转速和壁厚变化的趋势，给出了工艺系统发生颤振时的主频率。然后利用小波包处理信号的优势将剧烈颤振加速度信号进行小波包分解，根据能量和频段分布进行节点信号重构，得到小波包滤波后的颤振信号。为了了解车铣切削力在剧烈颤振前后变化情况，应用小波包分解并重构出颤振前后3种不同刀具转速时强迫振动信号，对比发现剧烈颤振时强迫振动的当量电压幅值增大，振动加强，这从侧面反映了正交车钪切削力的大小和变化。此振动分析对正交车铣薄壁零件有一定的指导意义。

Test Analysis on Vibration Signal of Thin Aluminium-alloy Cylinder Machined with Orthogonal Turn-Milling

The cutting test of orthogonal turn-milling thin aluminium-alloy cylinder was performed by MAZAK machine tool, piezoelectricity acceleration sensors fixed to inner wall of the cylinder, PCI- 1712 high speed data acquisition card used for acquiring vibration signals of the cylinder. The acquired acceleration signals were analyzed by MATLAB to obtain the vibration signals in time domain which sign the vibration amplitudes and their power spectral densities which display frequency structure and energy distribution. The tendency of varying self-excited frequency with rotating speed for cutter and wall thickness was analyzed, the main frequency of chatter from technology system was given in fre?quency domain ? The acute chatter signal was decomposed with wavelet packets and the node signal was reconstructed based on energy and frequency distribution of the chatter signal, to gain chatter signal fil?tered by wavelet packets. For understanding the change of turn-milling cutting force before and after acute chatter, the vibration signals of three different cutter rotating speed were decomposed and recon?structed with wavelet packets, to gain forced vibration signals. It is found by contrasting the three forced vibration signals that the forced vibration enhances at appearance of acute chatter with incre?ment of equivalent voltage of forced, vibration, which reflects the magnitude and change of turn-milling cutting force from one aspect. The above analysis of the vibration signal has guidance meaning to machining thin cylinder with orthogonal turn-milling.