Patent GB-1226091-A (GB)
IPC: G01N29/27
Filed: 1967-03-01
Abstract: 1,226,091. Ultrasonic inspection devices; probes. S.T.D. SERVICES Ltd. 28 Feb., 1968 [1 March, 1967], No. 9694/67. Addition to 1,121,903. Headings H4D and H4J. The apparatus of the parent Specification (Division H4) is modified in that there is provided (a) a ring controlling simultaneous angular adjustment of the carrier members, (b) a pair of spaced transducers on the or each carrier member, the transducers having the normals to their active faces co-planar and inclined at equal and opposite angles to the carrier member axis, or (c) an electronic circuit whereby the transducers on a plurality of carrier members are sequentially energized as transmitters and act as receivers in a synchronous sequence. In the embodiment described the body, 10, (Fig. 2) forms part of a test station through which the tube to be tested is advanced and rotated by skewed rollers. Twenty-four transducer carrier members 22 are spaced around a water-filled passage 9 through which the tube passes and each carries a pair of transducers having co-planar beams directed normally to or at opposite inclinations to the carrier member axis. The members 22 are provided with extensions 37 (Fig. 3), having faces 38 which are sprung against stops 39. Stops 39 are adjustable to give individual angular adjustments of the carriers 22 relative to body 10, and are carried on a ring 40 which can be moved by screw 45 to give a ganged angular adjustment which is indicated by pivoted pointer 47. In the Fig. 5 system the twentyfour transducers at the left-hand side (as seen in Fig. 2) of the carriers 22 act as pulse transmitters and the other twenty-four act as receivers. Generator 51 provides 180 degrees phase-shifted square-wave outputs at terminals 52, 53, and short pulses at terminal 54 coincident with the beginning of each squarewave at terminal 52. Ring counter 55 is clocked by terminal 52 output and its stages TR1-TR24 drive AND gates TG1-TG24 supplied also with terminal 54 output, whereby the transmitter transducer circuits T1-T24 are pulsed in turn at the beginnings of the terminal 52 square-waves. A second ring counter 56, enables gates RG1-RG24 in turn in the second half-cycles of the square-waves from terminal 52, to pass flaw echo signals from receiver circuits R1-R24 in turn to amplifier 57: this gating ensures that transmission has ceased before receiver-signals are passed to the amplifier. Gain control circuits GC1-GC24 for amplifier 57 are also enabled in turn by counter 56 and are individually preset so that variations in the sensitivity of the transducers and their gate circuits can be allowed for. The amplifier feeds a display 59, an alarm 60 and/or a flaw recorder 61. The transducer beam directions may be determined as in Specification 866,457. The transducers may be used as transceivers as described in Specification 1,226,092. Transducer details, (Fig. 4). Each carrier member 22 comprises a stainless steel tube apertured at each end to receive a lead zirconate transducer wafer 23 silvered on both sides and mounted on a tungsten powder-filled epoxy resin backing 24 in a copper tube 25. The transducer 23 is inductively coupled to transmitting/receiving circuits via coil 28 and an overwound coil 33 (Fig. 2), carried by the body 10. Reference has been directed by the Comptroller to Specification 1,121,904.