数控旋压机床旋轮架广义空间位置维动态特性分析

数控旋压机床是集旋压、自动化机械、液压伺服控制等多项先进技术为一体的高科技机床产品。数控旋压机床进行旋压件加工时的精度取决于加工过程中旋轮与芯模的相对间隙。随着数控旋压机床在加工过程中旋轮空间位置姿态的不断变化，旋轮架结构构形及轴间耦合作用也随之发生改变，导致旋压机机床动态特性预测具有复杂性和不确定性。针对企业提升大型双轮数控旋压机床动态性能的需求，基于虚拟样机技术，构建了考虑机床结合部动态特性参数的旋轮架系统动力学有限元模型，并基于实际加工工况进行模型边界条件设置。以一阶固有频率为主要参考指标，基于有限元分析模型修正法对旋轮架在广义加工空间中的不同位置进行了模拟模态分析和实验模态分析，研究了旋轮架的动态特性与广义加工空间位置姿态变化之间的关系。数字仿真分析和实验结果表明：对旋轮架一阶固有频率来说，不同位置点的模拟模态值与实验模态值总体吻合较好，平均误差率为2.21%；系统的一阶固有频率、振型及阻尼比随位置姿态的改变而变化；不同位置之间的最低与最高固有频率相差26%左右；X轴坐标越居中，Z轴坐标越大，旋轮架固有频率越低，旋轮振幅越大。证明旋轮架的不同空间位置姿态对旋压机床的动态特性影响较大。得到的结论可以用于研制新型旋压机床、优化加工路线和设计最优加工位置。

Dynamic Characteristics Analysis for Spinning Frame of CNC Spinning Machine Based on Generalized Manufacturing Space

CNC spinning machine is a high-tech machine tool which integrates the spinning system, automatic machinery system, hydraulic servo control system and other advanced technologies. The machining accuracy of CNC spinning machine is depended on the gap between spinning wheels and the core mould. Because of the change of spinning wheels'' positions and postures in manufacturing process, the spinning frame configuration and axis coupling forces will change accordingly, which causes complexity and uncertainty of predicting the spinning machine dynamic characteristics. In order to improve the characteristics of a two-wheels CNC spinning machine, a dynamic finite element model of spinning frame system was constructed based on virtual prototyping technology. The joint coupling forces and dynamic parameters were fully considered during the modeling process. The first order natural frequency was taken as the reference index for dynamic characteristics analysis. Simulated and experimental modal analysis were carried out throughout the whole manufacturing space using finite element model modified method, in order to investigate the dynamic characteristics of spinning frame and its variation with different positions and postures. Simulated and experimental results showed that the values from two different methods agreed with each other well with an average error rate of 2.21%. The first order natural frequencies, vibration modes and damping ratios were changed when the spinning frame was moving along X-axis and Z-axis. The maximum changing of first order natural frequencies was up to 26% comparing two extreme positions. When the coordinate of spinning wheel was larger at Z-axis and more centered at X-axis, the first natural frequency was smaller and the amplitude was higher. This indicated that the spatial positions and postures of spinning frame had great effect on the dynamic characteristics of spinning machine. The results can be used to develop new spinning machine tools, optimize processing routes and design optimal processing positions.