AUTOMATED-SYSTEM FOR LASER ULTRASONIC SENSING OF WELD PENETRATION

An on-line sensor is required for real-time control of penetration dep th in robotic welding. Currently, no on-line techniques exist for dire ct penetration depth measurement. The development of a penetration con trol system will significantly reduce the costs associated with repair ing or scrapping defective welds. Laser array generated ultrasound is a noncontact, nondestructive method that can potentially be used to me asure weld penetration. This paper will discuss the design and impleme ntation of an automated system that was used to measure the depth of s imulated solidified welds. The system consists of a laser array genera tion source and an electromagnetic acoustic transducer (EMAT) receiver . Measured penetration results for the simulated weld are compared wit h the exact results. Experimental results will also be shown for array gain measurements in order to demonstrate the power of the array. Thi s automated system is being modified in readiness for use in actual ro botic welding. (C) 1997 Elsevier Science Ltd.