深孔加工刀具系统的动态稳定域研究

The Dynamic Stable Region of Drilling Tools System in Deep Hole Drilling

根据广义Hamilton原理,构建了基于Timoshenko梁单元的多跨柔性回转钻杆横向振动的有限元模型。通过采用自由界面模态综合技术,在保证大型复杂深孔加工装备动力学分析精度的前提下,将钻杆线性自由度的特征模态进行截断,仅保留具有非线性动力特征的模态,其中舍去的高阶主模态则由剩余附着模态来补偿,从而使得耦合动力系统求解的自由度数有效降低,节约计算资源。利用该缩减后的模型,研究了辅助支撑位置、钻杆长度及排屑孔径对深孔钻杆固有频率的影响规律。以加工复合扁孔为例,获得了在选定的切削深度和切削速度参数空间中钻杆运动的失稳方式及稳定区域。研究结果表明,文中所提出的方法将为复杂深孔加工装备的动力学设计和加工精度分析提供理论基础。

Based on the extended Hamilton principle, the finite element model of lateral vibration of drill- ing shaft is established using Timoshenko element model. Under the condition of maintain nonlinear anal- ysis precision, the linear degrees of drilling shaft system will be truncated using mode synthesis technique with free-interface but its nonlinear degrees are retained in the physical space, and simultaneously, the e- liminated eigenmodes are compensated with the residual attachment modes. So the DOF of the coupled system is reduced. Based on the updated model, the natural frequency influence rules of the drilling shaft system, as changing the distance of the intermediate supports, the length of drilling shaft and its the inner diameter, are discussed. By drilling the structural style of intersection hole as an example, the dynamic stable region and instability modes of the drilling shaft system are analyzed under the different rotating speed and drilling depth in drilling process. The numerical results show that the proposed methods for the dynamic design of complex drilling deep hole machine and the analysis of machining accuracy provide a theoretical basis.