机床锥合固定结合部动力学建模及模型参数识别.doc

硕士学位论文 机床锥配合固定结合部动力学建模及模型参数识别 Research on Parameters Identification for NC Machine Taper Joints 摘 要 在机床整机设计的建模阶段中，机床结合部参数是机床各部件理论模型的重要边界条件，结合部的阻尼和刚度对机床结构的动态性能具有重要的影响。机床锥配合固定结合部就是其中一种重要的结合部，直接影响数控机床的高速、高精度加工。然而，锥配合结合部的处理方法不同，将会导致不同的分析结果，因此，建立一种有效的机床锥配合固定结合部动力学模型，以及精确识别结合部模型参数识别方法是本文研究的主要内容。 目前工程上常用一系列弹簧和阻尼器组成的粘弹单元连接固定结合部，该方法忽略了各粘弹单元之间和每个粘弹单元中各坐标方向之间实际存在的耦合关系，为克服这一缺点，本文首先提出了一种新的锥配合固定结合部的动力学建模方法。 针对XHK5140数控机床上的BT45号刀柄-主轴系统结构，设计了刀柄-主轴锥配合实验模型，在自由悬挂的条件下，运用LMS Test.Lab 8B振动测试系统对该模型进行了脉冲锤击法模态实验，得到了反映锥配合结合部动态特性的六阶模态频率及振型。 依据频响矩阵和阻抗矩阵的乘积为单位矩阵这一理论基础，建立了刀柄-主轴锥配合固定结合部动力学模型参数的识别方法，并用MATLAB编制了识别程序。 最后，将识别的模型参数通过大域格式DMIG卡片嵌入到MSC.Nastran有限元软件中，由振型相似，比较频率的方法分析了模型参数的求解误差，验证了锥配合固定结合部动力学模型的有效性。 关键词：锥配合固定结合部，参数识别，非线性最小二乘拟合，DMIG Abstract In the model building of the machine tool design stage, the machine tool joints parameter is the import boundary condition of the theoretical model, the damping and stiffness have a great influence on the dynamic characteristics of the machine tool structure. Of all the machine tool joints, the taper joints are very important, which have an direct effect on the processing of the high-speed and high-accruacy machine tool. However, different processing methods lead to different analyzing results. Therefor, the article will establish an effective dynamic model of the taper joints, and identify the taper joints model parameters precisely. At present, a series of viscoelastic elements, which contain spring-damper, are used to connect the fixed joints. However, the method ignores the coupling of the viscoelastic elements and different coordinate directions between them. In order to avoid these shortcomings, a new taper joints dynamic modeling method will be proposed in this paper. According to the BT45 toolholder-spindle structure of the XHK5140 CNC machine tool, a toolholder-spindle experimental model is designed in this paper. Then a pulse hammer excitation test is done on the toolholder-spindle experimental model, by using the LMS Test.Lab 8B vibratio