薄壁筒车削颤振表面纹理形成机理研究

Formation mechanism of chatter surface texture in thin-walled tube turning

切削颤振引起的加工表面纹理蕴含着丰富的加工状态信息。针对薄壁筒工件的车削颤振问题,采用理论分析、数值仿真和试验测试相结合的方法,研究切削参数、工件动态特性等因素对表面纹理形成的作用机理。首先利用有限元法获得一次完整走刀过程中薄壁筒模态随切削位置的变化规律,得出工件壳体模态的固有频率有明显的下降趋势。进而结合切削加工表面形貌模型,理论推导并解释了特殊振纹图案的形成与工件尺寸、单位时间内固有角频率的减少量和转过圈数的二次方有关。最后通过实时采集并提取车削过程中的颤振频率、工件尺寸以及切削参数,再现了薄壁筒表面特殊振纹,验证了理论分析的正确性。研究结果对于薄壁筒加工表面形貌的预测与控制具有指导意义。

The processed surface texture caused by cutting chatter contains abundant processing state information.Here,aiming at turning chatter problems of thin-walled cylindrical workpieces,a combination of theoretical analysis,numerical simulation and test measuring was adopted to study formation mechanism of surface texture under turning chatter.Effects of workpiece dynamic characteristics and machining parameters on surface texture formation were studied.Firstly,the finite element method was used to obtain variation laws of thin-walled tube modes with varying of cutting position in process of a complete cutting.It was shown that natural frequencies of workpiece shell modes have an obviously dropping trend.Furthermore,combined with the cutting surface topography model,the theoretical derivation and explanation showed that the formation of the special vibration texture is related to workpiece size,reduction of natural angular frequency per unit time,and square of revolution number.Finally,cutting tests were conducted to verify the theoretical analysis results.The chatter frequency,workpiece size and cutting parameters in turning process were collected and extracted,and the special vibration texture on thin-walled tube surface was reproduced.The results showed that this study is of significance for prediction and control of surface morphology of thin-walled tube in turning operations.