基于非线性吸振器的薄壁件切削振动控制

Vibration Control in Milling of Thin-walled Parts Based on Nonlinear Dynamic Vibration Absorber

在航空发动机的涡轮风扇及叶片等薄壁件在铣削加工过程中,由于材料切削困难、零部件刚度低以及加工中时变性强等原因易造成薄壁件出现颤振,导致加工精度降低及表面质量变差。利用动力吸振器可有效控制振动现象,但由于材料去除时被加工件等效参数变化而导致其模态频率迁移,易造成振动控制失效。为保证切削全过程中的有效振动控制,提出了非线性吸振器,建立了主系统耦合非线性吸振器的动力学模型,利用复变量平均法分析了系统的慢变方程,得出了系统发生鞍结分岔以及霍普夫分岔的边界条件,分析了激励频率对分岔边界及截断阻尼的影响。利用数值方法从时域及频域进行分析,得出了系统的能量谱,对比了非线性吸振器及线性吸振器的振动抑制性能,结果表明,非线性吸振器可在全频段有效进行振动控制,避免了引入线性吸振器引起的二阶共振。

In the milling process of thin-walled parts,such as turbine fan and blade of aeroengine,due to difficult material cutting,low component stiffness and strong time-varying in machining,thin-walled parts are prone to chatter during ma chining,resulting in reduced machining accuracy and poor surface quality.Dynamic vibration absorber technology can effectively control vibration,but due to the removal of materials and the change of equivalent parameters of machined parts,its modal frequency will migrate,which is easy to cause the failure of vibration control.In order to ensure the effective vibration control in the whole cutting process,a nonlinear vibration absorber is proposed.The dynamic model of the coupled nonlinear vibration absorber of the main system is established,the slow varying equation of the system is analyzed by using the complex variable average method.The boundary conditions of saddle node bifurcation and Hopf bifurcation are obtained,and the effects of excitation frequency on the bifurcation boundary and truncation damping are analyzed.The energy spectrum of the system is obtained by using the numerical method from the time domain and frequency domain.The vibration suppression performance of the nonlinear vibration absorber and the linear vibration absorber is compared.The results show that the nonlinear vibration absorber can effectively control the vibration in the full frequency band and avoid the second-order resonance caused by the introduction of the linear vibration absorber.