On-line measurement of free-form surfaces for manufacturing applications

Measurement of free-form surfaces is a requirement to assure quality and to reduce manufacturing costs and rework. An on-line measurement system combined coordinate measuring machine (CMM) and numerical controlled (NC) sandblast manufacturing equipment for large surface is presented in this paper. It uses transmission and position functions of NC machine and CMM´s scan measuring function to make large surface measurement correspondingly. By means of auxiliary coordinate axis, CMM and NC machine can establish a unified coordinate system, data transform and on-line measurement. To perform detailed comparison of the shapes, the CAD model is geometrically adjusted with the input using model-based a new matching algorithm developed in this paper. Once the CAD model is adjusted, it is compared with input to reveal the errors between their shapes. Following, process parameters in NC machine will be adjusted by the expert system based on the errors and neural networks. In this way the integration of on-line measurement and NC manufacturing have been accomplished.