OPTICAL MEASUREMENT OF FITTED BACK AXLE PARTS
An automobile manufacturer is looking for a fully automatic test stand for mounted rear axles to check the geometry of the two brake discs and the torsion bar on the axle. The positioning of the cameras makes special demands, since the installation possibilities are strongly limited by the interfering contours of the gripper system. Permissible tolerances of +/-0.5 mm occur for the torsion bars and the thickness of the brake discs, and +/-5 mm for the diameter of the brake discs.
ISW GmbH implemented a PC-based Visionscape image processing solution with a total of five high-resolution cameras. The rear axles are placed in the workpiece holder of the test station by a handling system with a gripper and the test sequence is then started. Each brake disc is recorded by two cameras for complete recording, whereby the measurement is carried out in transmitted light. The four cameras for the brake discs are connected via a frame grabber, the fifth camera for the torsion bar via a second frame grabber. Since the Visionscape software supports the simultaneous connection of several frame grabbers, the effort for this remains minimal. The geometry of the brake discs and the torsion bar is determined via contour recognition, evaluated, then compared with the pre-programmed nominal values and evaluated. NIO parts are marked and ejected. In addition, the test results are displayed on an operator terminal with a customer-specific user interface.
The implemented multi-camera system enables fast testing with all required criteria. The solution of connecting the cameras to a powerful PC system via frame grabbers allows a significantly faster and more powerful image processing system than a solution with intelligent cameras. Thanks to the efficient Visionscape software, ISW GmbH was able to develop a powerful and cost-effective solution within a short time in conjunction with proven hardware components.