| 摘要 |
FIELD: contactless ultrasonic inspection of materials and parts. SUBSTANCE: transducer has case accommodating bimorphous member in the form of thin metal disk mounted therein asymmetrically and in step manner that carries on one or both ends thin piezoelectric disks,in diameter, whereis bimorphous member bending-vibration wavelength at its high operating frequency; thin metal disk has radial slits made along lines of stepped variation of its attachment from side surface to that of piezoelectric disks; metal shields are mounted on operating and rear ends of bimorphous member at distance, whereis ultrasonic-vibration wavelength in gaseous medium at frequency f; shield mounted at working end has central hole whose diameter equals that of piezoelectric disk accommodating matching structure and horn. Design features proposed in addition are as follows: (1) diameter of bimorphous member should bewhere K=3,5,7...;is bending vibration wavelength o bimorphous member at its low operating frequency; (2) parts of piezoelectric ring should be placed on ends of each pair of opposite sectors of bimorphous member formed by radial slits, their inner and outer diameters being, respectively, ≥λ/2, ≅λ/2 + kλ, where K=1,3,5...; λis bending vibration wavelength at resonant frequency of nth pair of opposite sectors; piezoelectric disk of bimorphous member is connected to input of adjustable-gain amplifier with phase-shifting circuit and parts of piezoelectric ring, to its output; (3) one of piezoelectric disks placed on one of bimorphous member ends is connected to mentioned amplifier input and other one, placed on opposite end, to amplifier output. EFFECT: enlarged functional capabilities, extended operating frequency range and high effectiveness. 4 cl, 2 dwg |
