A Framework for Measurement and Analysis of Sheet Metal Parts

This paper presents an measurement and analysis system of sheet metal parts with large and complicated curved surfaces used widely for manufacturing applications. For such sheet metal parts, which is characterized by a great volume, a big area, deforming easily and its loading and unloading can be difficultly, the required accuracy and rigidity of the system are critical features. The purpose of the system is to inspect sheet metal parts before and after the remanufacturing process for avoiding a range of possible errors that can occur during the manufacturing process. In the system, the online measurement system (OLMS) developed with improved accuracy, flexibility and advanced measuring efficiency advantages, and the shape error analysis are used to assure quality and to reduce manufacturing costs and rework. The proposed shape error analysis approach first uses a statistical method to determine the number of test-points with suitable sample size. Then, the approach applies a robust mathematic model, implicit polynomials (IP), to construct the model of the test-points, following the geometrical adjustment of the CAD model and a report on detected shape errors. Therefore, the system can work well for sheet metal parts mentioned. Experimental results on measurement and analysis of a variety of the metal skin of aircraft are reported to show the performance of the system in manufacturing processes.