A Measurement and Analysis Technique of Curves of Metal Parts

Metal parts with large and complicated curved surfaces used widely have some characteristics such as a great volume, a big area, distorting easily. It is very difficult to measure and evaluate accurately the parts. Taking measurement of the parts as a purpose, a new measurement method called On-Line Shape Measurement System (OSMS) is put forward.Error analysis of curves is a requirement to assure quality and to reduce manufacturing costs and rework. This paper proposes a new approach and algorithms for the error analysis of curves.the system applies a robust mathematic model, Implicit polynomials (IP), to construct the model of the test-points. Once the CAD model is adjusted, it is compared with input to reveal the errors between their shapes. To accomplish this task a new shape matching algorithm is developed. Experimental results on error analysis of a variety of the machined metal skin of aircraft are reported to show the validity of the proposed methodology.