SU1341570A1 - Ferroprobe flaw detector - Google Patents

Abstract

The invention relates to non-destructive testing and can be used for remote monitoring of the surface condition of ferromagnetic steel products. The aim of the invention is to improve the accuracy and reliability of control due to automatic detuning from spurious signals that occur when the size of the gap between the flaw detector transducer and the surface of the test item changes. When the device operates, in the event of a sharp increase in the gap between the transducer 2 of the flaw detector and the surface of the tested product, the voltage of the 2nd and 3rd harmonics simultaneously increases, i.e. signals taken from the measuring windings of the converter 2, in case of exceeding the specified threshold from the output of the second measuring channel to the trigger input 13 a prohibition signal is received. The output signal from the trigger 13 closes the key 12, and the false signal from the threshold unit 7 does not go to the indicator 9. 1 Il. (L SP

Description

The invention relates to non-destructive testing and can be used for remote monitoring of the surface condition of ferromagnetic steel products.

The aim of the invention is to improve the accuracy and reliability of control due to the automatic detuning from a false signal that occurs when the gap between the flaw detector transducer and the surface of the product under test changes.

The drawing shows a block diagram of the fluxgate flaw detector.

The fluxgate flaw detector contains, subsequently, an excitation oscillator 1 and a fluxgate transducer 2, two measuring channels, each of which consists of a series-connected selective amplifier 3 and 4, an amplitude detector 5 and 6, and a threshold block 7 and 8, an indicator 9, the first driver 10 pulses, the input of which is connected to the output of the amplitude detector 5 of the first channel, the second driver 11 pulses, the input connected to the output of the threshold block of the second channel, the key 12 set between the threshold vym unit 7 and the first channel indicator 9, and a trigger 13 whose inputs are connected to outputs of shapers 10 and 11 pulses, and its output connected to a control input of switch 12.

In the device, the pulse shaper 10 is triggered from the falling edge of the signal arriving at it. input, and the driver 11 pulses from, the leading edge of the incoming signal. The fluxgate transducer 2 measures the gradient of the normal component of the magnetic field strength of the defect. The flip-flop 13 changes its state only when a pulse arrives at the input associated with the pulse shaper 11, and then when the pulse arrives at another input connected with the pulse shaper 10. Key 12, in the absence of a control voltage at its input, is open. Between the threshold unit 7 of the first channel and the keys 12 may be included the delay line.

Fluxgate flaw detector works as follows.

Ferrozondovy converter 2, placed between the poles of the electro

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a magnet (non-shown), is installed together with the latter on the surface of the control article (not shown). The generator 1 excites the flux-gate converter 2, the measuring windings of which are connected to the inputs of the selective amplifiers 3 and 4. The electromagnet moves along the tested surface of the product.

In the absence of defects under converter 2 and there is no change in the gap between the poles of the electromagnet and the tested surface of the unit, the voltage at the ends of the measuring windings of the converter 2 is absent, since the measuring windings are connected in opposite directions.

When a defect appears, under the converter 2, periodically varying voltage appears at the ends of its measuring windings, which is fed to the inputs of selective amplifiers 3 and 4, which isolate and amplify the second and third harmonics of the excitation current. The amplitude of the third harmonic of the defect signal is small compared to the second harmonic, therefore the signal is not received at the input of the imaging unit 11, the trigger 13 does not change state, and the control input of the switch 12 is not energized. Key 12 is open. At the output of the amplifier 3, a voltage appears, which is fed to the input of the amplitude detector 5 and from its output goes to the input of the threshold unit 7 and the driver 10 pulses. The generated pulse at the output of the driver 10 is applied to the input of the trigger 13, but does not change its state. If the voltage at the input of the threshold unit 7 exceeds the specified threshold amplitude selection, then through the key 12 it is fed to the input of the executive body, which is triggered.

With a sharp change in the gap, the voltage of the second and third harmonics simultaneously increases at one of the poles of the electromagnet. The voltage from the output of the selective amplifier 4 is fed through an amplitude detector 6 to the input of the threshold unit 8. When a predetermined trigger threshold specified during tuning is exceeded, a voltage appears at the input of the pulse former 11. A pulse shaper 11 is generated

a short pulse and is applied to the input of the trigger 13, which changes its state. The voltage detected at the output of the trigger 13 is applied to the input of the key 12. The key 12 is closed. The voltage received at the input of the key 12 from the output of the threshold unit 7 does not flow to the indicator 9. The key 12 returns to its original state only after the gap is removed under the pole, and the input voltage of the driver 10 disappears and a short pulse is generated, which returns trigger 13 to its initial state. Key 12 opens. The shunting of the key 12 is performed both with long-lasting signals from the output of the selective amplifier 4 and short signals when the monitored product is magnetized by a constant or alternating magnetic field.

The proposed flaw detector allows you to automatically rebuild from spurious signals associated with a sharp increase in the gaps between the poles of the electromagnet and the surface of E. Slygan 4431/49 surface.

Compiled by A. Cherkhikh Tehred M.Didzh

Cor Pod

Circulation 776 VNIIPI USSR State Committee

for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5

Production and printing company, Uzhgorod, st. Project, 4

whether that improves the accuracy and reliability of the control.

Claims (1)

Invention Formula A fluxgate flaw detector containing a series-connected excitation generator and a flux-probe 0 transducer, two measuring channels, each of which consists of a series-connected selective amplifier, an amplitude detector and a threshold unit, and an indicator, 5 is due to the fact that, in order to increase the accuracy and reliability of the control, it is equipped with the first pulse shaper, whose input is connected to the output of the amplitude detector of the first channel, the second shaper of the pulses, the input of which is connected to the output of the threshold block of the second channel, between keys a threshold unit of the first channel and an indicator, and a trigger, the inputs of which are connected to the outputs of the pulse formers, and the output to the control input of the key. Proofreader A.T. sko Subscription