基于能量分布的机床整机动态特性优化方法

基于机床结构中的能量分布,在准确建立立式加工中心整机有限元模型的基础上提出一种整机动态性能优化方法。采用弹簧阻尼系统等效结合部的接触特性,基于辨识的结合部等效刚度和阻尼值在Ansys中建立了立式加工中心整机有限元模型,对整机进行模态分析和谐响应分析。通过整机模态试验验证了该有限元模型的准确性,并根据有限元分析与试验结果确定整机的薄弱模态。计算薄弱模态下整机、结合部的弹性能以及结合部在整机中的弹性能分布率,以分布率较高的结合部作为薄弱结合部。基于薄弱结合部的等效接触刚度提出优化方案,优化后薄弱结合部的弹性能分布率明显降低,主轴轴端的动态响应幅值降低,从而使整机动态性能得到改善,验证了该优化方法的可行性。

Dynamic Characteristics Optimization for Whole Machine Tool Based on Energy Distribution

An optimized method for whole machine tool dynamic characteristics based on machine structure energy distribution is proposed after the finite element model (FEM) of a vertical machining center has been accurately established. The spring-damping system is adopted to establish the FEM with ANSYS to simulate the contact behaviors of its joint surface based on the identified joint stiffness and damping. Then, the modal characteristics and harmonic responses of the whole machine are analyzed. The FEM is verified to be accurate and the weak modes are obtained after comparing its results with that of the experiments. The elastic energy of the whole machine tool and the joints of these weak modes are calculated. The joints with a relatively high ratio of whole machine tool elastic energy are regarded as the weak joints. Finally, an optimized project based on the stiffness of these weak joints is proposed. The results show that the elastic energy ratio of each weak joint of the weak modes and the dynamic response amplitudes of the spindle tip decreases. Thus, the feasibility of this optimized method is verified with the improvement in the dynamic characteristics of the whole machine tool.