SU819709A2 - Acoustical method of flaw detection - Google Patents

Description

(54) ACOUSTIC DETECTION METHOD

one

The invention relates to the field of non-destructive testing and can be used to control the uniformity and uniformity of products.

The known acoustic method of defectoscopy is that resonant mechanical vibrations are excited in a controlled and etched objects, the number of resonant peaks of the controlled object is determined in a given frequency range, compared with the same number for the reference sample and the difference and resonant peaks are measured. about imperfection of sample 1

The disadvantage of this method is the impossibility of using it to determine the size of defects.

The aim of the invention is to expand the scope.

This goal is achieved by determining the frequency difference between the ocHOBHfcOM resonance peak corresponding to the reference sample and the additional resonance peak, judging the size of the defects.

FIG. 1 shows a functional diagram of the device that implements the method: in FIG. 2 - frequency spectrum

The sample is defect free and the sample is defective.

The device contains a series-connected audio frequency generator 1, a piezo emitter 2, a core-conductor 3, sample 4, a core-conductor 5, a piezo receiver b, an amplifier 7, a detector 8, a differentiating device 9, a diode 10, a driver 11 standard pulses and a frequency meter 12, an input which is connected to the output of the generator 1 audio frequency.

With the aid of an audio frequency generator 1, the frequency of which varies within pre-selected limits, a piezo emitter 2 is excited, which is fixed on the core guide pipe 3.

The oscillations generated by the piezo emitter 2 propagate along the core-sound guide 3 and excite oscillations of the sample, recorded through the core-sound guide 5

6. When the frequency of the generator 1 with resonance “and the oscillation frequency of the test sample coincide, the amplitude of the oscillations of the latter increases sharply. This voltage

amplified by amplifier 7.

 the signal is detected by detector 8, at the output of which pulses appear, corresponding to the passage through the resonance of the sample under study. At small defect sizes, the sample under study may have similar resonance peaks. In order to separate the electrical pulses that display the amplitude-frequency characteristic, they are differentiated by device 9 and rectified by diode 10. The received pulses are fed to the former 11 standard pulses, which starts the frequency counter 12. Thus, the frequency meter 12 passes through the resonances of the sample under study. registers its resonance peaks.

FIG. 2 shows the frequency difference between the main resonance peak 13, corresponding to the reference sample, and the additional resonance

peak 14, which depends on the size of the defect.

The use of a flaw detection method allows one to estimate the size of defects in controlled samples.

Claims (1)

1. USSR author's certificate No. 655961, cl. G 01 N 29/04, 1977 (prototype). / 40 thirty 50 70 kHz 60