SU1649419A1 - Acoustic emission method of test of conducting components - Google Patents

Abstract

The invention relates to non-destructive testing of acoustic emission signals (A3) and can be used for quality control in thermal cathode production technology. The aim of the invention is to improve the accuracy and sensitivity of the control of thermal cathode heaters due to the time selection of AE signals from current pulses, which excite AE in the heater. AE signals are excited by pulsed current, they are received after passing through the acoustic immersion medium. 1 il.

Description

The invention relates to non-destructive testing of acoustic emission (AE) signals and can be used for quality control in thermal cathode production technology.

The purpose of the invention is to improve the accuracy and sensitivity of the control of the heaters of thermal cathodes due to the temporary selection of AE signals from current pulses that excite AE in the heater.

The drawing shows a block diagram of a device for implementing a method of acoustic emission monitoring of electrically conductive materials.

A device for implementing the method of acoustic emission monitoring of electrically conductive materials contains a metal bath 1 with an immersion medium 2 (liquid), a series-connected pulse generator 3 and a current generator 4, sequentially

United one-shot 5, electron

. key 6, amplifier 7, comparator 8 and meter 9 of the energy of AE signals. The device also contains a piezoelectric receiver 10 connected to the second input of the electronic key 6 and located on the surface of the metal bath 1, the second output of the pulse generator 3 is connected to the input of the one-vibrator 5 and to the second input of the meter 9 of AE signal energy. A controlled 11 | is connected to the output of the current generator 4 and immersed in the immersion

, liquid 2 at a distance from the piezoelectric receiver 10.

The method of acoustic emission monitoring of electrically conductive materials is implemented as follows.

A controlled helix (heater, heater) 11 is placed in a bath 1 filled with an immersion medium, for example, alcohol. Spiral 11 is placed on rasNvA

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standing from the piezo receiver 10. The distance is chosen from the conditions. Јts -r- where v g, is the speed of sound in the immersion medium, Јand is the current pulse duration of the current generator 4. Through the coil 11, a current of microsecond duration is passed, the amplitude of the current I is determined from the expression

I YTG.ShPG

G LTSt I I J

where DT is the amplitude of the temperature pulse (does not exceed the boiling point of the liquid) C is the specific heat capacity} m is the preheater mass, R is the ohmic resistance.

As a result, generate spiral

11 thermoelastic voltages leading to the occurrence of AE signals from defective zones of the helix 11. AE signals are received in an immersion medium at a distance of 1 from the helix, providing a delay of acoustic impulses for a time Sdd measure the energy of AE signals by the meter 9 of AE signal energy the magnitude of which is judged on the quality of the spiral. The one-vibrator 5 delays the control signal from the pulse generator 3 to the time of propagation of AE signals in the immersion medium. The delay of the signals provides an increase in the measurement accuracy by eliminating the effect on the recording part of the device of the impulse of electrical pickup from the current generator 4. The immersion medium also reduces the effect on the useful AE signal of natural spiral oscillations excited by a current pulse I.

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Claims (1)

Thus, the proposed method allows to increase the accuracy and sensitivity of the control due to the delay of AE signals and filtering the natural acoustic oscillations of the control object. Invention Formula The method of acoustic emission monitoring of electrically conductive objects, which consists in creating a stress-strain state in the object by passing an electric current through the object and recording acoustic emission signals, determine the defectiveness of the object according to the parameters of signals, increase the accuracy and sensitivity of the thermal cathode heaters, the heater is placed in a liquid immersion medium and microsecond pulses of electric current are passed through it, taking Acoustic emission signals in an immersion medium at a distance from the preheater provide delaying acoustic pulses for time Ј IM (T, measure the energy of AE signals, the magnitude of which determines the quality of the preheater, and the amplitude of the electric current is chosen from the ratio . / 2  GYG Cm V 2 L kDimp J temperature pulse amplitude specific heat capacity of the preheater, preheater mass, ohmic resistance, current pulse duration.