The Development And Precision Analysis Of WXJJⅡ Precision Assembly System

Most micro parts are usually not completed by one time, they need to be rigged out to achieve their features. Currently the micro parts rely on operations to achieve picking, pose adjusting, placing and installing and other works, but it received a great influence on the accuracy and efficiency, the assembly workers need highly professional skills to finish the work, so it is difficult to meet the rapid development market economy. Therefore it is an urgent need for new technology to solve this situation.The emergence of precision assembly technology largely solved the problem. Currently precision assembly systems are mostly based on the machine vision, it achieved a flexible automated assembly. The appearance of precision assembly technology made the function of assembly system improved, and it also lower the cost of assembly operations.Contrary to the characteristics of the parts to be assembled, this paper designed a precision assembly system—WXJJ II precision assembly system. And according to the function requirements, the system is divided into four modules:assembly operations module, visual measurement module, workbench module, man-machine operation modules. The assembly operations module is made up by manipulators, precision motion guides etc, it can achieve parts picking, shipping, drop acting, and it also can detect changes in the force during the processing to finish the assembly; workbench module is made up by precision turntable, the material base and the mounting base, it can achieve the pose adjusting of the parts, the fixing of assembly processing and other functions; visual measurement module is made up by the imaging system, three-axis precision motion guide,1394 image acquisition boards and other components, it can collect the feature information of the parts to be assembled, and also can guide the precision assembly. Manual operation modules can analyze the image information collected by camera and can complete the automated assembly of parts and emergency stop action.This paper focuses on the factors affecting the accuracy of the assembly system. Factors that can influence this assembly system mainly include the camera error, the image processing error, the rail error, the coordinate angle error and so on. In which the camera error, the image processing error and the rail error impacts the final assembly precision slightly, the coordinate angle impacts largely. So in order to reduce the workload and avoid introducing other errors, we can ignore the image processing error and the rail error, just compensating to the coordinate angle error, and make the final accuracy of precision assembly meet the requirements.According to the assembled parts information, the articles designed a parts assembly strategy and introduced the positioning method of the parts in the assembly strategy in details. In the processing of assembling, the identification and location of the parts are finished by getting the image information after collecting the images by machine vision. Combining the visual processing technology, this article introduced the image processing method which was used in the assembly processing. Finally, this paper used a set of components to be assembled in this assembly system to verify the repeatability and stability of the system, the result showed that the coaxial accuracy was within ±10μm.