SU1392487A1 - Device for flaw detection of ferromagnetic parts - Google Patents

Description

(21) 4158112 / 25-28

(22) 12/08/86

(46) 04/30/88. Bksh. Number 16

(71) Omsk Institute of Railway Engineers

(72) C. A. Isakov, R. A. Akhmedzhanov, Yu. A. Popkov and A. A. Buldakov

(53) 620.179.14 (088.8)

(56) USSR inventor's certificate 1035503, cl. G 01 N 27/90, 1984.

(54) DEVICE FOR DEFECTOSCOPY OF FERROMAGNETIC PARTS

(57) The invention relates to non-destructive testing of materials and products. The purpose of the invention is to increase the reliability of the control due to the automatic selection of the optimal control mode. This goal is achieved through the use of a self-tuning circuit formed by a second transducer 7 and an amplitude detector 8, as well as a differential amplifier 9, a comparator 10, a linearly varying voltage generator 11, a memory element 12, an adder 13 and a waiting multivibrator 15. 4 or so.

SL

The invention relates to non-destructive testing of materials and products and can be used to detect defects in ferromagnetic parts with an untreated complex surface, in particular in cast steel parts of railway carriage running gears.

The aim of the invention is to increase the reliability of control by automatically selecting the optimal control mode by the excitation frequency of the eddy current transducer.

FIG. 1 shows a functional scheme of the device; in fig. 2 shows the amplitude-frequency characteristics of airborne transducers in air in FIG. 3 - the same, on the metal; in fig. A - timing diagrams for the operation of the device.

The device contains serially connected frequency controlled oscillator 1, first eddy current transducer 2, first amplitude detector 3, signal increment analysis unit 4 and indicator 5, phase detector 6 whose inputs are connected to the output of the generator 1 and to the output of the converter 2, and the output is connected with the second input of unit 4, the second eddy current transducer 7, the second amplitude detector 8, the differential amplifier 9, the second input of which is connected to the output of the first amplitude detector 3, connected in series comparator 10, generator 11 of linearly varying voltage (GLINE) memory element 12 and adder 13, the output of which is connected to the control input of the generator I, source 14 of the reference voltage (ION), the output of which is connected to the second input of the adder 13, and The waiting multivibrator 15, the input of which is connected to the output of the comparator 10, and the code connected to the second input of the memory element 12.

The device works as follows.

The first eddy current transducer 2 is operative and is installed on the test surface of the part, and the second eddy current transducer 7 is located far from the test surface (in air). When the device is turned on, when both transducers 2 and 7 are far from the monitored surface, their amplitude-frequency characteristics practically coincide. At the same time, the input U of the generator 1 has a voltage U (Fig. 4), which is converted into a sinusoidal signal with a frequency Gdp where K is the conversion factor of the generator 1, and the outputs of the converters 2 and 7 appear almost equal to the voltage after being converted by the detectors 3 and 8, they are fed to the inputs of the differential amplifier 9. At the output of the latter, a voltage signal close to zero is formed, which is fed to the input of the comparator 10. When the input voltage of the comparator 10 is below the threshold value, a zero signal level is maintained, which is fed to the inputs of the CLAY 11 and the multivibrator 15. At the same time, the CLINE II is closed, i.e. at its output the signal level is close to zero, the multivibrator 15 is not excited, the memory element 12 repeats at its output a zero signal from CLAY 11, therefore the adder 13 transmits only the signal to the input of generator 1

and

And he

ION 14 output.

When transducer 2 is mounted on a part, its amplitude-frequency characteristic shifts to lower frequencies, with the result that a differential voltage Di appears between the inputs of differential amplifier 9, which triggers the comparator 10 and forms a signal U at its output. LIN 11 is started. Since there is no signal at the control input of the memory element 12, and its transfer coefficient is equal to one, it transmits a rising voltage from the output of GLINE 11 to the input of the adder 13. At the output of the latter, the resulting voltage U is generated, which causes frequency increase Oscillator 1. This process lasts as long as the output signals of transducers 2 and 7 are not matched at a frequency fp. At this moment, the output voltage of the differential amplifier 9 becomes less than the threshold, the comparator 10 returns to its initial state, the backing of its pulse is waiting for the waiting multivibrator 15, transferring the memory element 12 to the storage mode of the input voltage CLIN 11. For the duration weekend

4.0

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Fi.2

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Claims (1)

Claim A device for flaw detection of ferromagnetic parts, containing a series-connected generator, eddy current transducer, amplitude detector, signal increment analysis unit and indicator, and a phase detector, the inputs of which are connected to the outputs of the generator and transducer, and its output is connected g to the second input of the signal increment analysis unit, characterized in that, in order to increase the reliability of control, it is equipped with series-connected second eddy current transducer connected to the output a generator, a second amplitude detector, a differential amplifier, the second input of which is connected to the output of the first> amplitude detector, a comparator, a ramp generator, a memory element and an adder, the output of which is connected to the generator input, a reference voltage source, the output of which connected to the second input of the adder, and a waiting multivibrator, the input of which is connected to the output of the comparator, the output of the multivibrator is connected to the second input of the memory element and the third input of the analysis unit when spins of the signal, and the generator is made controlled by frequency. Fy. " 2