An improved method of and apparatus for ultrasonically testing butt welds

摘要

862,031. Ultrasonic wave couplings. BABCOCK & WILCOX Ltd. Sept. 18, 1959 [Sept. 19, 1958], No. 30035/58. Class 40 (4). [Also in Group XL (c)] For inspection of a butt weld 63, Fig. 9, a probe 4 carries transducers which direct ultrasonic waves in different directions 10, 11 and is rocked in the plane of the paper on the surface of workpiece 60. It is stated that attenuation is thereby reduced as compared with an oscillatory probe head arrangement as described in Specification 803,551 and deeper welds may be examined. The probe consists of transmitting and receiving sections 1, 21, Fig. 5, separated by a layer of acoustic insulation 17. The transmitting section comprises a block of transparent plastic 9, see also Fig. 1, on which is provided fault-finding transducers 2A, 2B and contacttesting transducers 3A, 3B arranged to operate as described in Specification 778,166, a predetermined delay being provided between the pulses supplied to the former and the latter transducers and the received echoes being displayed on a cathode-ray tube (C.R.T.); the display is photographed to provide a record. The inclination of facet 5 is such that the beams 12, 13 from transducers 3A, 3B intersect face 4 at respective regions corresponding to the beams 10, 11 from transducers 2A, 2B. The gap between the base of the probe and the workpiece is filled with a liquid couplant. Further transducers may be provided for inspection of weld 63 at more than two depth regions, with a corresponding increase in the number of transducers for contact testing. The regions tested are arranged to overlap. For inspecting workpieces having flat or concave outer surfaces the contact face of the probe is made convex. The probe is mounted on a carrier arranged to be rocked in a carriage movable along a track by a mechanism as described in Specification 803,551. Springs urge opposite ends of the probe carrier towards the workpiece and, to impart the rocking motion, the springs are compressed by oppositely phased eccentrics driven from a common shaft, Figs. 10 ... 13 (none shown). The carriage for the probe carrier carries a switch lever co-operating with equidistantly spaced actuators on a track rail so as to show by an indication on the C.R.T. the location along the weld to which the test results relate. According to the Provisional Specification the transducers are piezo-electric.