龙门加工中心进给系统动态特性分析及结构优化

发布时间：2018-06-13 19:51

本文选题：进给系统 + 动态特性　；参考：《山东大学》2017年硕士论文

【摘要】：进给系统是数控机床的重要组成部分,进给系统的设计要符合特定的条件,从而确保进给系统具有优异的静动态性能,最终保证数控机床的几何精度、运动精度以及加工精度。随着数控机床不断向高精度、高速度发展,进给系统的振动成为制约加工中心性能改善及加工精度提高的重要因素之一。因此,对进给系统进行动态特性研究与结构优化一直受到机床制造厂商和专家学者们的广泛关注。本文结合国家重大科技专项"高速龙门五轴联动加工中心"课题(2012ZX04006-011),采用实验测试与仿真分析相结合的方式建立进给系统的虚拟样机,开展进给系统的动态特性分析与结构优化工作。完成的主要工作如下:首先,建立进给系统动力学虚拟样机,仿真进给系统在不同条件下的运动,获得动力学参数。利用Ansys与Adams创建进给系统动力学虚拟样机模型,利用谐响应分析得到工作台X向的固有频率。并对切削以及快速进给条件下的进给系统进行了动力学分析,得到丝杠的驱动力矩,进行了进给系统电机匹配性研究。同时分析了丝杠副接触刚度、轴承轴向刚度以及工作台质量对工作台振动频率的影响。其次,结合仿真模型与实验测试对进给系统的振动特性进行分析研究,获得其模态参数。利用东华DH5922N信号采集分析系统完成了切削激励与快速进给条件下的进给系统各部分的振动响应的测试与分析,通过实测发现工作台振动加速度信号中的强迫与固有频率振动的成分,与仿真得到的固有频率进行对比,可以为虚拟样机建立的准确性提供参考。设计了模态测试方案,完成了模态测试;建立了较为准确的进给系统有限元模型,进行了模态分析,得到进给系统前六阶模态振型与频率,确定进给系统变形较大的部位,为下一步的进给系统结构优化提供指导。最后,利用Workbench对进给系统进行结构与拓扑优化,提高伺服进给系统动态特性。对工作台内部筋板结构进行了尺寸优化,在工作台不增重的前提下提高了工作台的固有频率和刚度。对进给运动传动链中丝杠螺母副以及丝杠两端的支承轴承副的轴向刚度对工作台振动频率的影响程度进行了分析。对床身轴承座安装部位处的筋板结构进行了拓扑优化,提高了丝杠支承轴承的轴向支承刚度。本研究对优化龙门加工中心进给系统和改善机床静动态性能,进而提升机床的加工质量具有一定的指导意义。
[Abstract]:Feed system is an important part of NC machine tool. The design of feed system should conform to the specific conditions, so as to ensure the excellent static and dynamic performance of the feed system, and finally ensure the geometric accuracy, motion accuracy and machining accuracy of NC machine tool. With the development of NC machine tools to high precision and high speed, the vibration of feed system has become one of the important factors that restrict the improvement of machining center performance and machining precision. Therefore, the dynamic characteristics of feed system and structural optimization have been widely concerned by machine tool manufacturers and experts. In this paper, the virtual prototype of feed system is established by combining experiment test and simulation analysis with the national important science and technology project "High-speed gantry five-axis linkage machining center" project (2012ZX04006-01111). Carry out dynamic characteristic analysis and structure optimization of feed system. The main work is as follows: firstly, the virtual prototype of feed system dynamics is built, and the dynamic parameters are obtained by simulating the movement of feed system under different conditions. The virtual prototype model of feed system dynamics is created by Ansys and Adams, and the natural frequency of the worktable in X direction is obtained by harmonic response analysis. The dynamic analysis of the feed system under the condition of cutting and fast feed is carried out, the driving moment of the lead screw is obtained, and the motor matching performance of the feed system is studied. At the same time, the effects of the contact stiffness of the screw pair, the axial stiffness of the bearing and the quality of the worktable on the vibration frequency of the table are analyzed. Secondly, the vibration characteristics of the feed system are analyzed and studied by combining the simulation model and the experimental test, and the modal parameters are obtained. The vibration response of each part of the feed system under cutting excitation and fast feed is tested and analyzed by using the Donghua DH5922N signal acquisition and analysis system. The components of forced vibration and natural frequency vibration in the vibration acceleration signal of the worktable are found by actual measurement, and compared with the natural frequency obtained by simulation, which can provide a reference for the accuracy of building the virtual prototype. The modal testing scheme is designed, the modal testing is completed, the more accurate finite element model of the feed system is established, the modal analysis is carried out, the first six modal modes and frequencies of the feed system are obtained, and the deformed parts of the feed system are determined. Provides the guidance for the next step feed system structure optimization. Finally, the structure and topology of the feed system are optimized by the Workbench to improve the dynamic characteristics of the servo feed system. The internal stiffened plate structure of the worktable is optimized, and the inherent frequency and stiffness of the worktable are improved without increasing the weight of the worktable. The influence of axial stiffness of the screw nut pair and the supporting bearing pair on the vibration frequency of the table is analyzed. The structure of the stiffened plate at the mounting part of the bearing seat of the bed body is topology optimized, and the axial support stiffness of the leadscrew bearing is improved. This research has certain guiding significance for optimizing the feed system of the gantry machining center and improving the static and dynamic performance of the machine tool and then improving the machining quality of the machine tool.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG659

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