Case Study 3.2: Semiautomatic Tool Reference for Application on Large Parts

Abstract

For large parts machining, workpiece set-up is a time-consuming and usually an error prone process. Large parts of unitary or very small batches are located in the machine using previously designed references in its surfaces according to machining specifications (marking out process). Both, the marking out process and the alignment in the machine are normally manual processes. The part has to be aligned according to machine axes. This process is done normally for each workpiece using touch probes or dial indicators. Zero point systems are conventionally not used in large parts machining. A 3D metrology system based on photogrammetry technology has advantages with respect to the marking out process: quick response, high precision in the captures, and the easiness to use. A photogrammetric application was developed here with the goal of producing parts with minimum material removal. An on-board solution was developed to control positioning of the part in the machine according to photogrammetric application requirements. Also, a kinematic alignment table was developed with the ability to rotate in three degrees of freedom simplifying the alignment process of the part in the machine. Finally, the developed system was validated in an industrial environment.