【作者】 张涛；

【导师】 王晓东；

【作者基本信息】 大连理工大学 ， 微机电工程， 2010， 硕士

【摘要】 在多环片零件的轴孔装配中,环片类零件特征尺寸小、装配精度要求高,故依赖于手工作业,对操作者的经验和技巧要求很高,工作强度大,且人为因素较多,严重影响了装配的质量和效率。而自动化的精密装配系统以其柔性化装配的特点,在提高装配精度、保证产品一致性以及提高生产效率等方面,均显示出极大的优越性。本文针对多环片零件的轴孔装配及检测作业的特点,研制了自动化的精密装配与检测系统,并围绕面向多环片零件的装配控制及检测关键技术展开研究。在分析了系统所需实现功能以及技术要求的基础上,确定了系统装配及检测原理,搭建了精密装配与检测系统,其主要由装配及取出作业、检测作业、作业平台、计算机控制四个功能模块组成,对系统各组成模块进行分析介绍,并简要描述了系统的控制结构体系及控制软件架构。对环片类零件的轴孔装配模型及相关问题进行了分析,围绕柔顺夹持、跳动及偏摆补偿及不合格零件取出等多环片零件轴孔装配的关键技术展开了研究。基于前述研究,在系统的装配及取出作业模块集成了柔顺夹持机构、跳动偏摆检测机构和不合格零件取出机构等功能部件。装配作业基于被动柔顺夹持机构以及自动装配控制方法实现,针对本文环片装配过程中阻力较大的特点,提出了一种新的装配力/刚度综合补偿控制方法,通过对装配过程中的装配力及导轨变形量进行检测,计算得到系统刚度,并据此实时预测装配位置偏差量,对装配目标位置进行修正和补偿。对装配作业过程进行合理规划和控制,减小分度转动等装配中间环节所引起的装配误差,提高系统装配精度。对位于狭小封闭装配孔内的多环片零件的位姿检测采用视觉检测方法实现,采用硬杆内窥镜实现了狭小无照明空间内的图像采集。针对内窥镜图像畸变,提出了一种基于硬杆内窥镜的精确测量方法,通过结合内窥镜的测量位置信息及采集到的图像信息来获得被测零件的位置和姿态信息。在LabVIEW平台上基于IMAQ Vision视觉模块进行图像处理程序的开发,包括图像增强、滤波、锐化,测量区域拾取,边缘检测、提取及拟合等步骤,最终实现对零件中心位置的精确检测。实验表明,所研制的精密装配与检测系统能够成功地完成多个环片零件在装配模具中的精密装配及检测,装配与检测的最大绝对误差均能控制在9μm之内。更多还原

【Abstract】 Most peg-hole assembly of multiple ring parts with small size and high assembly precision requirement, are assembled manually by experienced and skilled workers, with high intensity and many factitious factors, thus the quality and efficiency of assembly is influenced greatly. With the characteristic of flexible assembly, automatic and precise system shows the advantage in improving assembly precision and coincidence, and increasing production efficiency. A precise assembly and measurement system is developed according to the characteristics of peg-hole assembly and measurement of multiple ring parts, and the key technology of peg-hole assembly and measurement for multiple ring parts is deeply studied.Based on the analysis of the system function and technological requirements, the assembly and measurement principle is determined, and the precise assembly and measurement system is established. The main function modules of this system, which including assembly and remove module, measurement module, operation platform module and computer control module, are introduced, then the architecture of control system and software are described briefly.After analyzing the assembly model and related problems of ring parts assembly, the study on key technologies of assembly including compliant gripping, axial runout compensation and unqualified parts removing is done. Based on the above study, a compliant gripping mechanism, an axial runout measurement mechanism and a removing mechanism are integrated into the assembly and remove module. The assembly of multiple ring parts is achieved based on the compliant gripping mechanism and automatic assembly control method. A new assembly force and stiffness synthesis compensation method is proposed to improve the assembly precision under a large system deformation caused by large assembly force. The system stiffness cvan be calculated out according to the assembly force and deformation measured during the assembly procedure, and then real-time prediction of system deformation can be achieved, thus the assembly destination position could be modified to ensure the assembly precision. The assembly error caused by the intermediate link, such as indexing rotation, can be decreased through reasonable assembly process plan, therefore the assembly precision can be improved. Vision-based measurement method is adopted to measure multiple ring parts assembled in the narrow assembly hole, and a rigid borescope is taken as the image transmission device to achieve image transmission in narrow space without illumination. To eliminate the influence on measurement caused by the borescope image distortion, a precise measurement method based on rigid borescope is proposed. In this method, the position and attitude information of the ring part to be measured can be obtained by combing the measuring position information and image information of the borescope. The image processing in the measurement operation, comprising enhancement, filtering, sharpening, picking measurement area, edge detection, extraction and fitting, is achieved by using IMAQ Vision toolkit built in Lab VIEW, and the center of the ring part can be measured precisely at last.The experimental results show the developed system can successfully achieve precise assembly and measurement for multiple ring parts in the assembly mold, and both of the assembly and measurement precision can be controlled below 9μm.更多还原