Improving accuracy of robot-guided 3D laser surface processing by workpiece measurement in a blink

A double-beam deflection unit (scanner) with integrated on-axis sensors for distance and temperature measurement is developed for the production of structural hybrid composite parts. This robot-guided 3d laser scanner is integrated in a composite production cell for in-mold laser pretreatment for subsequent joining. A basic challenge of industrial laser applications - the placement problem of workpiece in workspace of robot - was solved using on-axis low-coherence interferometry. Varying positions of workpiece for remote laser processes can in the future be compensated in seconds, depending on beam characteristic, here with a theoretical accuracy of 60 μm (X,Y), 1 μm (Z), 0,003° (B,C) and 0,174° (A). Two issues reduce this theoretical accuracy in practice. However, the improvement of daily process preparation is significant and validated by measurement of accuracy of laser path image at a close-to-series carbon fiber reinforced plastic (CFRP) demonstrator of BMW. The optimal position of scanner relative to part is a fundamental condition for ablative 3d surface processing. Driven by the necessity of quality assurance within automotive industry the inherent potential of sensor technology is shown, additionally. This potential study gives impulses for further developments of multifunctional laser scanners.