Basic Studies On Accuracy Management System for Shipbuilding

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One of the most significant issues in assembly industries is accuracy management of products. Accuracy management is deeply related with product quality, manufacturing efficiency, costs and so on. Accuracy management will be more and more important in the future manufacturing systems. In this research we propose computer aided accuracy management systems based on the concept of a product model.There are two significant ways for accuracy management. One way is "accuracy planning", and the other way is "accuracy measurement". The former is accuracy management in production design stage to make production plans in the view of accuracy of products.. The latter is accuracy management in real assembling stage to evaluate accuracy of built products.For accuracy planning, it is important to estimate deformation in assembling stages. We propose models to estimate easily weld deformation of products. The concepts of equivalent stiffness and equivalent loading (that is equivalent shrinkage force and equivalent bending moment) of a welding are introduces to estimate deformation for FEM linear analysis. According to assembling procedure, deformed shapes of products are easily understood. By using them ideal shape of initial parts and an ideal shape of intermediate products in each production stage can be gotteen.For accuracy measurement we propose two types of computer models of products. Those are an ideal shaped model and a real measured shaped model. When a measurement is carried for special points on ideal shaped model, the implemented system describes these measured values in measured model. Furthermore we make clear the function for difference evaluation between two types of shaped models. The first function is setting a position. And the second function is interpretation of difference of coordinates into shape accuracy inrotmation. Differences of two shapes are evaluated by the concept of a tolerance zone inside of a computer.