With conventional tactile measurement technology, individual points on the surface are probed, from which conclusions can be drawn about the dimensional accuracy of the component. However, component geometries can only be checked incompletely by evaluating a few individual points.

For this reason, Schuler has opted for an automated solution based on a 3D scanner from GOM. This delivers high-resolution 3D coordinate measurement data of sheet metal body parts and tools. Using the new measuring system, components up to the size of vehicle side panels can be checked completely and quickly for shape and dimensional accuracy. Full-surface comparison with the target geometry is also possible.

The optical robot measuring cell is mobile and can be used at other Schuler sites as well as at customers' premises.

© Schuler

"Because we can now measure the entire component geometry at once, we can set up the tools much faster," explains Schuler Managing Director Udo Binder, who heads up the toolmaking department. "Thanks to the high quality of the measurement data, we also improve the quality of our tools and require less corrective grinding. In addition, we can scan and digitize the tools ourselves and compare them with the data from the design department."

In order to capture the component spatially, the measuring sensor projects a precise stripe pattern onto the object surface, which is captured by two cameras using the stereo camera principle. As the beam paths of both cameras and the projector are known in advance thanks to the calibration, 3D coordinate points can be calculated from the three different beam sections. This triple scan principle offers advantages when measuring reflective surfaces, among other things.

The innovative measurement technology is particularly suitable for complicated structural parts such as side members and B-pillars or for outer skin parts such as doors, front and rear flaps, roofs and complete side panels. It allows the component geometry to be recorded seamlessly, which both speeds up the tool production phase and ensures quality in series production. Throughout the entire process chain, changes can be quickly displayed and easily interpreted, for example by means of a target/actual comparison as a false color representation on an image.

The punctual measurement of components using tactile measuring methods is inevitably always incomplete and may require further measuring passes; in addition, surfaces must be created at great expense using a CAD workstation. In contrast, the complete and area-based recording of optical measurement technology means that the digitized component can be evaluated at any point at any time.

For reverse engineering, the generated data can be read out as STL polygon meshes and further processed in CAD. Direct CNC milling on the STL data set is also possible during tool post-processing. Last but not least, the 3D measurement data makes it possible to validate and optimize the simulation software used. This accelerates and improves the development work of future tools.