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1、华 中 科 技 大 学 硕 士 学 位 论 文I摘要摘要多轴加工系统的综合动态特性对加工过程、工件的表面质量、机床和刀具的寿命等都有着至关重要的作用。加工系统由机床本体、各运动轴、主轴、刀柄、刀具、工件等构成，可以分为刀具子系统和工件子系统两大部分，加工系统的动态特性常用频响函数来描述。刀具子系统和工件子系统的动态特性对整个加工系统的动态特性有着影响，整体加工系统的动态特性由刀具子系统和工件子系统的动态特性共同决定。本文针对多轴加工系统的动态特性进行了研究，使用实验和有限元相结合的方法得到加工系统的综合频响函数。本文主要从以下几个方面进行了研究。首先，推导了加工系统综合频响特性与刀具子系统和工
2、件子系统频响函数的关系。其次，建立了刀具子系统动力学模型，采用实验和有限元仿真相结合的响应耦合方法预测刀尖点频响函数，以均匀分布的弹簧、阻尼模拟刀具-刀柄结合部之间的柔性联接，用实验和仿真相结合的方法辨识刀具-刀柄结合部的刚度和阻尼系数，可预测不同刀具刀柄组合以及不同刀具姿态时的刀尖点频响函数，并通过实验验证了刀具子系统动力学模型的可行性。然后，建立了工件子系统动力学模型，考虑了工件夹持支撑等因素对工件子系统动态特性的影响，通过建立完整的工件有限元模型来预测工件上不同位置的频响函数，并通过实验验证了工件子系统动力学模型的准确性。最后，利用建立的加工系统动力学模型分析了刀具长度变化、刀具直径变化
3、、刀具姿态变化等因素对刀尖点频响函数的影响，预测了工件子系统中工件各方向不同位置的频响函数变化。关键词：多轴加工系统 综合频响函数 响应耦合 有限元法 华 中 科 技 大 学 硕 士 学 位 论 文IIAbstractDynamic characteristics of multi-axis machining system play vital roles on surface quality of the workpiece, the life of machine tool and cutting tools. The machining system consists of machi
4、ne bed, axis of motion, spindle, tool holder, tool and workpiece. It can be divided into two subsystems, which are tool subsystem and workpiece subsystem. Frequency Response Function (FRF) is broadly used to describe dynamic characteristics of the machining system. Obviously, dynamic characteristics
5、 of tool subsystem and workpiece subsystem have certain influences on dynamic characteristics of the entire machining system. In this thesis, dynamic characteristic of muti-axis machining system are investigated; experimental and finite element methods are combined to acquire the machining systems g
6、eneral frequency response function. The main contents are as follows. Firstly, the relationship between machining systems general FRF and the two subsystems is deduced. Secondly, dynamic model of the tool subsystem is established. A novel response coupling method, which applies both experimental and
7、 finite element simulation to acquire FRFs of the tool point, is proposed. Uniform distributed spring and damper elements are used to simulate dynamic characteristics of the joint between tool and holder. Experiment and simulation is applied to identify stiffness and damp coefficients of the joint b
8、etween tool and holder. This method can be carried to predict FRFs of varied combination of holder and tool. The feasibility of the tool subsystems dynamic model is verified by experiments. Then, dynamic model of the tool subsystem is established, considering the influence of the workpieces clamp an
9、d rest on dynamic characteristics of the machining system. The workpiece finite element model is performed to predict FRFs at different location of the workpiece. The accuracy of the workpiece subsystems dynamic model is verified through experiments. Finally, the proposed dynamic model of machining
10、system is applied to analyze the influence of tool length, tool diameter and tool posture on the tool points FRFs, and to predict the different positions FRFs on the workpiece.Keywords: Muti-axis machining system General frequency response function (FRF) Response coupling Finite element method 华 中 科
11、 技 大 学 硕 士 学 位 论 文III目录目录摘要摘要.IABSTRACT.II1 绪论绪论.11.1 课题来源.11.2 研究目的和意义.11.3 国内外研究现状.21.4 本文的主要研究工作.62 加工系统综合频响特性概述加工系统综合频响特性概述.72.1 加工系统综合频响函数概述.72.2 频响函数的获取方法.112.3 模态参数识别方法及频响函数评价指标.132.4 本章小结.153 加工系统刀具子系统动力学建模加工系统刀具子系统动力学建模.163.1 刀具子系统的总体模型.163.2 刀具刀柄结合部参数识别.183.3 刀尖点频响函数预测.213.4 本章小结.254 加工系统工件子系统动力学建模加工系统工件子系统动力学建模.274.1 工件子系统总体模型.274.2 夹盘夹持和中心架支撑参数识别.284.3 工件子系统频响函数预测.
