义齿加工五轴机床的设计分析及实验验证

发布时间：2018-02-11 05:04

本文关键词： 义齿加工五轴机床方案设计伺服系统结构优化　出处：《哈尔滨工业大学》2017年硕士论文　论文类型：学位论文

【摘要】：牙齿在人们的饮食以及语言、发音、面部肌肉形态的保持等方面发挥着巨大的作用,牙齿健康问题是人们当前关注的一个焦点。CAD/CAM的兴起使得义齿修复体的手工制作方式逐渐被数控加工所取代。然而我国义齿修复体的制作方式仍然主要以手工制作为主,精度不稳定,加工效率低、操作环境差。针对这个问题,我国每年需要花费大量资金引进国外先进的义齿加工设备,而且设备的后期维修成本高,这严重阻碍了我国口腔修复水平的提高,因此研发具有自主知识产权的义齿加工设备,是提高我国口腔修复水平的重中之重。本课题以高效高精地完成义齿修复体的加工为目的,对义齿加工设备的功能需求进行了分析,然后以此为基础对机床进行了结构布局设计、运动功能分配、工作空间规划等工作,最终设计出了一台用于义齿加工的五轴数控机床。机床本体的精度是影响机床最终加工精度的关键因素。本文依据多体系统理论建立了机床的空间误差模型;利用矩阵偏微分法对模型进行了误差敏感性分析,定义了敏感度系数,对关键误差源进行了识别,为提高机床精度提供了指导性意见;建立了基于成本—公差的精度分配模型,利用遗传算法对机床进行了精度分配,确定了机床的精度指标。伺服进给系统是数控机床的关键部分,其运行性能的好坏直接影响到机床的加工精度和加工效率。本文在对常用的伺服进给方式进行对比分析的基础上,确定了机床的进给方案;对伺服进给系统进行了机电耦合数学建模;依据自动控制理论对伺服进给系统进行了设计;制定了控制参数;对所设计的伺服系统进行了仿真,分析了系统的动态特性,验证了系统的运行性能。机床各部件的静动态特性直接决定着机床本体的加工性能。本文采用有限元对对机床性能影响较大的重要结构部件进行了力学性能分析,并据此对其进行了优化设计以提高其静动态特性;对机床整体进行了静力学与动力学特性分析,找出了机床的薄弱环节,提出了下一步的改进意见。最后本文用所设计的机床样机进行了义齿加工的初步实验,加工实验表明本课题所设计的五轴机床所加工出的义齿能够满足口腔修复的临床要求,并且该机床具有很高的加工效率。
[Abstract]:Teeth play a huge role in people's diet, language, pronunciation, facial muscle shape, etc. The problem of dental health is a focus of people's attention at present. The rise of CAD / CAM makes the handmade method of denture prosthesis gradually replaced by numerical control machining. However, the manufacture of denture prosthesis in our country is still mainly made by hand. The precision is unstable, the processing efficiency is low, and the operating environment is poor. In view of this problem, our country needs to spend a large amount of money every year to introduce advanced foreign denture processing equipment, and the maintenance cost of the equipment in the later stage is high. This seriously hinders the improvement of the level of dental prosthesis in China, so the development of denture processing equipment with independent intellectual property rights, It is the most important to improve the level of dental prosthesis in our country. The purpose of this project is to finish the denture prosthesis with high efficiency and precision, and to analyze the functional requirements of the denture processing equipment. Then on the basis of this, the structural layout design, motion function distribution, workspace planning and so on are carried out on the machine tool. Finally, a five-axis NC machine tool for denture machining is designed. The precision of the machine body is the key factor affecting the final machining accuracy of the machine tool. In this paper, the spatial error model of the machine tool is established according to the theory of multi-body system. The error sensitivity of the model is analyzed by matrix partial differential method, the sensitivity coefficient is defined, the key error source is identified, the guidance is provided for improving the accuracy of machine tools, and the accuracy distribution model based on cost tolerance is established. The precision of machine tool is assigned by genetic algorithm, and the precision index of machine tool is determined. The servo feed system is the key part of NC machine tool. The performance of the machine has a direct impact on the machining accuracy and efficiency. Based on the comparative analysis of the common servo feed methods, the feed scheme of the machine tool is determined. The servo feed system is modeled by electromechanical coupling; the servo feed system is designed according to the automatic control theory; the control parameters are formulated; the designed servo system is simulated, and the dynamic characteristics of the system are analyzed. The operating performance of the system is verified. The static and dynamic characteristics of the components of the machine tool directly determine the machining performance of the machine body. In this paper, the mechanical properties of the important structural parts which have great influence on the machine tool performance are analyzed by using finite element method. In order to improve the static and dynamic characteristics of the machine tool, the static and dynamic characteristics of the machine tool are analyzed, and the weak links of the machine tool are found out. Finally, the preliminary experiment of denture processing with the designed machine tool prototype is carried out. The processing experiment shows that the denture manufactured by the five-axis machine tool designed in this paper can meet the clinical requirements of oral prosthesis. And the machine has a high processing efficiency.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG659

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