자동차 부품 Bracket의 CF 검사구 개발에 관한 연구

Abstract

In a global age, the technology competitiveness is the key for knowing an international position of certain country compared with others. If the country had higher technologies to produce complicated products or assembly parts, it surly seems for that country to have international competitiveness. Nowadays a lot of products have a variety of geometric characteristics to be used for application fields such as machinery, automobile, aerospace, shipbuilding, heavy machinery and semiconductors. The main consideration in a case of manufacturing these complicated products is cost effectiveness and reliability of the product quality by reduction of the number of process, new process development and automation system. In addition, the development of a CNC (Computerized Numerical Control) machine tool can help to make geometrically malformed products and parts. In recent, products were measured with new generation of advanced measuring instruments including a tool microscope, a projector of products and three dimensional measuring devices, while a vernier calipers, a micrometer was used conventionally for measuring the length of products. Using the traditional instruments such as the vernier calipers, outer diameter of the products, inner diameter, depth and width were tested without any exact reference lines of that product. When this kind of measurement was performed, sometimes it can’t assemble with his counterparts although all contents of the measurements were acceptable because of no references. It is the reason that each tolerance will be accumulated according to the contents of measurements. So it is seen that reducing the accumulated errors had a limitation or was impossible when two dimensional measurements were carried out. On the other hands, the measurement by three dimensional devices has some benefits of accuracy of measuring data in certain case with below 0.001 mm resolution. But the measurements using these devices appear serious problems such as time consuming, a lot of maintenance cost and skilled operator. To solve these problems of measurements, the development of an enhanced measuring device is necessary. A CF (Checking Fixture) is one of the alternatives for easy and precise measurements. The CF can be defined as follows. “It is a user-oriented instrument for checking easily geometric precision and dimensional accuracy of the products for mass production system.” In this study, a novel CF for automobile bracket parts was developed with the concept of minimizing the static deformation and maximizing the life time in a design stage. The selection of suitable materials and the machining technique of the CF were proposed. The developed CF was evaluated with three dimensional devices of contact and non-contact types. Finally, the CF was applied to the real field of automobile company to compare the measuring efficiency with conventional devices.