GB1150680A - Material Tester - Google Patents

Abstract

1,150,680. Ultrasonic inspection devices. AUTOMATION INDUSTRIES Inc. 29 Sept., 1967 [18 Oct., 1966], No. 44422/67. Addition to 1,141,046. Heading H4D. A system for ultrasonically inspecting a workpiece comprises rotatable cylindrical transducers for engaging the workpiece, and means responsive to that part of the ultrasonic energy which persists in the workpiece when transmission into the workpiece has terminated. In the Fig. 1 embodiment for detecting delaminations in plywood panels 12 fed to testing station 14 by conveyer 24, pulse transmitting transducers 26 on arms 34 pivoted at 35 are moved into contact with a panel by pneumatic cylinders 36 which exert a pressure insufficient to compress unbonded plies together but sufficient to ensure good acoustic coupling through resilient tyres on the transducer surfaces. The transducers are paired with similar receiving transducers on pneumatic cylinders 42. Gate circuits coupled to the receiving transducers effect blanking of received signals during the transmission pulse period so -that only ultrasonic energy reverberating between the upper and lower panel surfaces is detected. If such energy is not detected in a predetermined interval the presence of a de-lamination of a corresponding predetermined size is indicated and paint sprays are actuated to mark the panel at the relevant position. Instead of the above through-transmission inspection, a pulse-echo inspection is envisaged. The transducers (Fig. 3) comprise piezo-electric cylinders 52 rotatable on ball-races 50 and having a resilient rubber or polyurethane tyre 60. Electrical signals to or from the cylinders are coupled inductively to external circuitry via coaxial rotor coil 56 and stator coil 58.