Development of on-line automatic monitoring and measuring system for Objet Rapid Prototyping Machine

• Main Authors: Chang-tai KO, 柯錩泰
• Other Authors: 鄭逸琳
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/7s75zr

碩士 === 國立臺灣科技大學 === 機械工程系 === 94 === The Rapid Prototyping (RP) techniques manufacture the parts layer by layer by automated machines. Most of the RP machines do not have monitoring systems to detect the fabrication errors and stop itself. In this study, we developed an automatic on-line monitoring and measuring system for Objet’s EDEN330. When the errors occur, the system could alarm the user and stop the machine to reduce further damages. Moreover, it would provide measuring function during processing. The on-line visual monitoring system consists of four modules— the image capture module, PLC controlling program, mechanism assembly module, and image inspection software. The image capture module took and stored images. The PLC controlling program commanded the image capture module to work, and activated the alarm if mistakes happened. Mechanism assembly module supported the image capture components in a fixed position. The image inspection software was the main monitoring program in this system. Two detecting methods were used– automatic area comparison method and contour interval comparison of point coordinates method. The automatic area comparison method compared the area of captured picture with the area of the sliced model. The acceptable ratio was set between 0.9 and 1.1. The contour interval comparison of point coordinates method compared with the distances of point coordinate, and the maximum allowable value is 10 Pixels. The monitoring system was successfully tested by 2.5D and 3D models with simulated errors. When the mistakes were detected, the alarm was triggered and the RP process was terminated. This system also provides measuring function. In this study, diameter of a circle and the distances between two lines were measured. Spoke function was used to obtain diameter, and Rake function together with linear equation and point distance equation was used to obtain distances between two lines. A benchmark RP part was built, and certain dimensions were measured and compared with the literature.