QH-3型数控机械手的特性分析及优化

发布时间：2019-05-28 08:59

【摘要】：在当今工业生产中,数控技术越来越趋于成熟,为了大幅度提高工业自动化水平,数控机床功能部件的研发至关重要。机械手作为数控加工中心的关键部件,介于主轴和刀库之间,主要作用就是将下一个工序所用的刀具和即将完成加工的当前工序所用的刀具进行调换,这样可以提高加工效率。因此,本文以QH-3型数控机床换刀机械手为研究对象,针对现有机械手结构中存在的不稳定的因素,对其进行三维建模、运动学验证、有限元分析和疲劳分析,找出其中薄弱的环节,对其结构进行优化,该方法具有重要的理论指导意义以及实际应用价值(在机械手的设计初期可以作为参考)。其中主要的研究内容与数值分析结果如下:首先,既详细介绍了数控机床机械手在国内外历史上发展的研究状况从而引出本课题的研究意义又简单表述了有限元法的中心思想和它广泛的应用,对现有机械手的图纸中的每个零部件进行三维建模,然后再将其组成一个完整的机械手系统;对机械手系统进行分析,掌握系统里面各零部件的作用,就可以有针对性的进行运动学分析,通过建立坐标系和运动方程论述机械手的工作过程,因为该工作过程符合机械手实际的运动方式,所以得出的方程是正确的。其次,对机械手进行静态和模态分析。将简化后机械手的模型导入到ANSYS Workbench中得到有限元模型。静力分析主要目的就是得出机械手的最大变形和应力、应变,并给出了变形和应力云图。从云图中分析了最大变形和应力发生的部位,为机械手的优化提供了思路。模态分析时,首先阐明了机械手进行模态分析的必要性,模态分析后得出机械手前六阶固有频率和振型,通过振型图得出会影响机械手抓取刀具精度的振型。最后,对机械手进行优化设计和花键轴的疲劳寿命分析。针对静态分析中得出机械手中固定手爪处产生的位移比较大,故对固定手抓进行了优化;对固定手爪单独分析优化后重新装配再进行静力分析,得到的位移相对于优化前的减小了16.6%,说明优化的部位是正确的。优化后整个机械手的固有频率发生了改变,其中第一阶固有频率(基频)相对于优化前的得到了增加,这也从侧面验证了优化部位的合理性。随后,分别对花键轴在轴向力和扭矩这两种情况下进行了疲劳分析,得出花键轴在这两种情况下的损伤云图和寿命云图,从两张云图中可以清楚地得到危险点和寿命较长的部分,这也为后续的优化提供了依据。本文仿真分析的结果对数控机械手后续研究具有一定的理论上的参考意义。
[Abstract]:In today's industrial production, numerical control technology is becoming more and more mature. In order to greatly improve the level of industrial automation, the research and development of functional components of CNC machine tools is very important. As the key component of NC machining center, the manipulator is between the spindle and the tool storehouse. The main function of the manipulator is to replace the tool used in the next process with the tool used in the current process that is about to be completed, so that the machining efficiency can be improved. Therefore, in this paper, the tool changing manipulator of QH- 3 CNC machine tool is taken as the research object, and the 3D modeling, kinematic verification, finite element analysis and fatigue analysis are carried out according to the unstable factors existing in the existing manipulator structure. To find out the weak links and optimize its structure, this method has important theoretical guiding significance and practical application value (which can be used as a reference in the early stage of manipulator design). The main research contents and numerical analysis results are as follows: first of all, This paper not only introduces in detail the research status of the development of CNC machine tool manipulator at home and abroad, which leads to the research significance of this subject, but also briefly describes the central idea of finite element method and its wide application. The 3D modeling of each component in the drawing of the existing manipulator is carried out, and then it is formed into a complete manipulator system. By analyzing the manipulator system and mastering the function of each part in the system, the kinematic analysis can be carried out, and the working process of the manipulator can be discussed by establishing coordinate system and motion equation. Because the working process accords with the actual motion mode of the manipulator, the equation is correct. Secondly, the static and modal analysis of the manipulator is carried out. The model of the simplified manipulator is imported into ANSYS Workbench to obtain the finite element model. The main purpose of static analysis is to obtain the maximum deformation and stress and strain of the manipulator, and to give the deformation and stress cloud diagram. The location of maximum deformation and stress is analyzed from the cloud image, which provides an idea for the optimization of manipulator. In modal analysis, the necessity of modal analysis of manipulator is expounded at first. After modal analysis, the first six natural frequencies and vibration modes of manipulator are obtained, and the vibration modes that will affect the accuracy of manipulator grasping tool are obtained by mode diagram. Finally, the optimal design of the manipulator and the fatigue life analysis of the splice shaft are carried out. In view of the static analysis, it is concluded that the displacement at the fixed hand in the mechanical hand is relatively large, so the fixed hand grip is optimized. The static analysis is carried out after the fixed claw is analyzed and optimized separately, and then the static analysis is carried out, and the displacement obtained is reduced by 16.6% compared with that before optimization, which indicates that the optimized position is correct. After optimization, the natural frequency of the whole manipulator is changed, and the first natural frequency (fundamental frequency) is increased compared with that before optimization, which also verifies the rationality of the optimized position from the side. Then, the fatigue analysis of the splice shaft under the axial force and torque is carried out, and the damage cloud diagram and the life cloud diagram of the splice shaft in these two cases are obtained. The dangerous points and long life can be clearly obtained from the two cloud images, which also provides the basis for the subsequent optimization. The results of simulation analysis in this paper have certain theoretical reference significance for the follow-up research of NC manipulator.
【学位授予单位】：兰州理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TP241;TG659

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