레이저 노출량이 3차원 측정기의 성능 평가에 미치는 영향

Abstract

Modern manufacturing industries are facing many challenges such as global competition and fast-changing consumer demands. These challenges call for the adoption of a concurrent engineering method. The concurrent engineering is a systematic approach to integrated design of products and their related processes, which are including design, material processing, machining, delivery and service support. For reducing time consuming from design to manufacturing of products, a reverse engineering, which directly obtains a geometrical data from scanning of the actual product, has been commonly used in recent. There are two ways to obtain the geometrical data from the product in the reverse engineering. The one is a scanning method by a three dimensional contact type scanner, which has an orthogonal coordinate mechanism and a stylus probe. This type has an advantage to get relatively accurate data. On the other hand, a three dimensional non-contact type scanner usually based on the laser application has a fast scanning speed. Because of its high speed character, most manufacturing companies have occupied this type as a three scanning system. However, the non-contact type laser scanner has a serious problem which comes from a basic mechanism for obtaining data. In this method, in order to obtain a geometrical data, the measuring system sends a laser light stream to an object to be measured and receives the light reflected from the object. As well known, the laser light only can go straight. Thus, if the object in measurement has a complicated geometry or a flexible surface, it is impossible to obtain precise data due to the limitation of the used light source. Therefore, a study for getting accurate data in the laser scanner system of the three dimensional non-contact type is more necessary. In this study, to solve this problem, a simple and practical way is proposed by using a magnet flux which is a kind of laser exposure agents used in the reverse engineering. At first, to evaluate the effect of the magnet flux on the accuracy of the measured data, a preliminary experiment using a standard block gauge was conducted and a measuring error compared with a computer modeling data was analyzed according to different laser exposure intensities. To know influence of the geometry of the object, measuring error in drilled holes and end-milled pockets machined on the aluminum block were examined. As a result of experimentation, it was seen that the geometrical properties at the object measured played more an important role than the laser exposure intensity in the three dimensional non-contact scanning.