Automatisierte und kontaktfreie Überprüfung von Schweißpunkten für die Automobilindustrie
Spot welding is a critical step in the production of car bodies, but the ultrasound inspection of the spot welds is still done manually, leading to high costs. Unfortunately, automation of this process is extremely challenging because the coupling fluid cannot easily be applied on the car by a robot. For a cost-efficient, automated inspection, a contact-free method compatible with alignment accuracies of a few millimeters is needed. Based on the optical microphone, XARION has developed an innovative solution that no longer requires coupling fluids and is suitable for robot-automated NDT inspection. The compact sensor head comprises the optical microphone together with an excitation laser, which is used for ultrasound excitation: a short laser pulse generates a broadband guided ultrasound wave directly in the material. After it has travelled through the spot weld, the optical microphone ‘hears’ the ultrasound radiated into the air. The scanning procedure determines the spot weld quality in only a few seconds, and an alignment accuracy of about five millimeters is sufficient and compatible with modern industrial robots. Because of its compact geometry, the sensor head can also inspect spot welds that are hard to reach.