【作者】 东辉；

【导师】 于慎波；

【作者基本信息】 沈阳工业大学 ， 机械电子工程， 2011， 硕士

【摘要】 随着数控机床加工精度要求的提高,其结构也越来越复杂,随之引起的机床振动问题愈加严重,引起了人们的普遍关注。机床振动对工件加工质量、加工速度及刀具与机床的寿命都有很大的影响。本文主要针对数控机床伺服系统振动特性进行研究。首先,利用有限元软件对永磁同步电动机进行了电磁场分析,计算电动机空载和加载后的磁场,并对其进行了对比,得到了电磁场中随位置变化径向磁密、切向磁密、径向力密度以及切向力密度的波形图。利用编程控制转子旋转,得到永磁同步电动机瞬念磁场的变化规律,绘制出径向磁密、切向磁密、径向力密度和切向力密度随时问变化的波形。电动机转矩脉动的主要来源是电动机的切向磁密。通过前面的分析可以计算电动机转矩脉动并绘制出转矩脉动波形图。在此基础上,提出了一种有效抑制电动机转矩脉动的方法,即改变电动机定子槽槽口参数,降低电动机的转矩脉动。通过多组数据的计算对比得出该型号电动机的最佳参数及对应的转矩脉动的数值。以上计算分析为优化永磁同步电动机设计提供了参考。其次,对机床的切削振动进行了研究。基于切削振动的产生机理,利用解析法求出不同转速下数控机床的极限切削宽度,对机床实际加工生产有一定的参考意义。运用有限元软件对刀架系统进行模态分析并提取出各阶固有频率,计算了切削力作用下的刀架变形。最后,分析了丝杠系统的刚度和变形对数控机床振动特性的影响。根据计算公式算出丝杠系统的刚度,考虑丝杠的变形因素主要来自切削力和电动机转矩脉动的综合作用,为了更加直观的观察丝杠的变形情况,采用有限元软件进行瞬态动力学分析,得到了电动机旋转一周的时间内丝杠受力变形的变化规律。更多还原

【Abstract】 The structure of NC Machine Tool is more complicated as high accuracy requirements. The problem of machine vibration causes serious concern. Machine vibration affects machining quality and cutting speed, furthermore, it makes a shorter life of tool and machine. Therefore, this paper foci on the study of vibration characteristics of the NC machine tool servo-system.First, Permanent Magnet Synchronous Motor is analyzed with the finite element software.The magnetic fields with no load and load are calculated and compared. The wave figures of radial flux density, tangential flux density, radial force density and tangential force density varied with position are gotten. Rotor of rotation is controlled by the program for a better research on the changes of motor magnetic field. The wave figures of radial flux density, tangential flux density, radial force density and tangential force density varied with time was drawn. Then the changing regulations of transient magnetic field were derived. Motor torque ripple resulted from motor tangential flux density, so the motor torque ripple and the torque waveform figure are got basing on the analysis of magnetic field of motor. On this basis, an effective method of suppressing motor torque ripple is proposed. The motor torque ripple is reduced by changing the parameters of motor stator slots The Optimal parameters are obtained from multiple results comparison. The calculation and analysis provide the basic design reference for the permanent magnet synchronous motor.Secondly, cutting vibration of machine tool is calculated. According on the generating mechanism of cutting vibration, the limits of cutting width are calculated by analytical method in different speed. It provides references for actual machining. Natural frequencies are extracted through modal analysis of cutter system with the finite element software. The cutting system deformation is also analyzed.Finally, the influence of stiffness and deformation of ball lead screw system on the vibration characteristics of NC machine is explored. The stiffness of ball lead screw system is calculated according to the calculation formula. The ball lead screw deformation results from cutting force and motor torque ripple. The figures of the screw deformation changing in one cycle are drawn by transient dynamic analysis with the finite element software, which shows more directly the ball lead screw deformation.更多还原