Noncontact Ultrasonic Sensing of Weld Pools for Automated Welding.

摘要

Contacting ultrasonic techniques can determine the geometry of the molten/solid interface and detect conditions which could lead to defect formation. However, the couplant required is a potential source of contamination in the weld and may be difficult to use under industrial conditions. Stress waves can also be generated and detected using noncontacting techniques. Ultrasonic stress waves are generated by focusing a beam from a pulsed laser on a stationary weld pool formed on the surface of a steel plate or on a weld pool in a fillet weld. The transmitted ultrasound is detected by an electromagnetic-acoustic transducer (EMAT). The signal received by the EMAT provides information about the properties of the pool, including the geometry and defect generating conditions. This information can be input to an intelligent controller. The ultrasonic system described in this paper is being developed as a portion of the sensing and control system for a completely automated welder. 11 refs., 5 figs. (ERA citation 14:011546)