SU1293623A1 - Ferroprobe flaw detector - Google Patents

Abstract

The invention relates to non-destructive testing means, products, and can be used in various fields of mechanical engineering, including power engineering, for defectoscopy of welded joints of boiler units. The purpose of the invention is to increase the accuracy and reliability of the control. The goal is achieved by the operation of the flaw detector with both a constant and alternating field created by a magnetizing device using the first restarted former 6, which forms a square pulse, the duration of which is compared by the logic unit 8 with the duration of the pulse generated by the second driver 7. At the same time, at the output of block 8, in the event of a false defect, the voltage does not appear and the recorder 9 does not notice the presence of a defect. 1 il.

Description

The invention relates to nondestructive testing by the fluxgate method of products made of ferromagnetic materials and can be used to detect defects in all areas of mechanical engineering.

The purpose of the invention is to increase the accuracy and reliability of the control by reducing the number of false readings by selecting signals of transducers in terms of duration.

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

The fluxgate flaw detector contains a series-connected excitation current generator 1, a ferro-probe converter 2 (gradiometer), a selective amplifier 3 (for example, a second harmonic amplifier of the excitation current frequency), an amplitude detector 4 (full-threshold threshold unit 5, the first pulse shaper 6 (for example, rectangular), the second pulse shaper 7, serially connected logic block 8 and the defect recorder 9, the third pulse shaper 10. The shaper 7 and 10 are connected by their inputs to the output of the driver 6, and the outputs to the inputs of the logic unit 8.

The first driver 6 may be implemented, for example, in the form of a one-shot with a restart. The second driver 7 can be performed, for example, in the form of a one-shot with the start of the leading edge of the pulse of the driver 6, and the third driver 10 - in the form of a single-shot with the start from the rear edge of the pulse of the driver 6.

Logic unit 8 passes a signal to the input of the recorder 9 defects while simultaneously receiving signals to its inputs. The registrar 9 can be performed, for example, in the form of a pulse extender and a light

scoreboard I

The fluxgate flaw detector operates as follows.

A flaw detector electromagnet (for example, an alternating current) is installed on a test surface (not shown). The flux-bridging converter 2 is installed between the poles of the electromagnet and moves with it when scanning the surface. Include generator 1 then

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By energizing the converter 2 and the power source of the electromagnet (not shown), the electromagnet is moved along the test surface.

In the absence of defects at the output of the converter 2, the voltage is absent, since its measuring windings are connected in opposite (according to the gradiometer scheme).

When a defect appears under converter 2, the voltage of the latter is the voltage from which the second amplifier of the field current is extracted by the selective amplifier 3 and fed to the input of the amplitude detector 4. Since the magnetization is performed by an alternating field, the output of the detector 4 or several pulses (depending on the scanning speed), which arrive at the input of the threshold unit 5. When the specified discrimination level is exceeded (set during tuning with the help of a test sample), they are then sent to od shaper 6 which form a rectangular pulse arriving at the input of 7 and 10.

The duration of the rectangular pulse of the imaging unit 6, when one short pulse arrives at its input, is set somewhat longer than half the period of the magnetizing current. Since shaper 6 is repeated start, upon receipt of dv at its input, ooh or more pulses, the time between which arrival is not less than half the period of magnetizing current, a rectangular impulse will be formed, the duration of which is equal to the time interval between the arrival of the first and of the last pulse plus the duration of the rectangular pulse from a single pulse at the input. The pulse duration of the imager 10 is small — up to several tens of microseconds. And the pulse duration of the imaging unit 7 is relatively long and is set based on the sensor transit time over a defect, for example, a crack or pore.

 With the passage of the Converter 2 over the defect, the pulse duration of the driver 6 is slightly less than the pulse duration of the driver 7. Therefore, a short pulse of the driver 10 is fed to the input of logic unit 8 simultaneously with the arrival of the driver of the driver 7 to another input. The recorder and the recorder 9 will mark the presence of a defect.

When the transducer 2 is moved over a spurious defect (for example, structural heterogeneity), its output is subjected to a voltage. However, the extent of structural heterogeneity is much larger than the width of the defect. Therefore, the duration of a rectangular pulse of driver 6 will be much longer than the duration of pulse of driver 7. A short pulse of driver 10 will arrive at the input of the logic unit after passing the pulse of driver 7. Logic block 8 will not pass the signal. Registrar 9 will not work.

When the poles of an electromagnet are detached from the test surface at the output of the converter 2, voltage is applied. Shaper 6 will be

: a rectangular impulse is formed. the duration of which is much longer than the duration of the pulse. Foror A. Revin 379/48

Compiled by A. Bodrov Tehred V. Kadar

Corre Poppy

Circulation 777 VNIIPI USSR State Committee

on affairs of inventions and otkryggy 113035, Moscow, Zh-35, Raushsk nab., d. 4/5

 Production and printing company, Uzhgorod, st. Design, And

worldr 7. Logic block 8 will not pass the signal to the recorder 9. The flux-gate detector also works when the monitored product is magnetised by a constant field.

Claims (1)

Such an embodiment of the flux-gate detector allows the selection of the flux-gate converter signals in amplitude and duration, which increases the accuracy and reliability of the control. Claims of the invention Fe1) are a probe-type defectoscope containing a series-connected generator, a flux-gate converter, a selective amplifier, a detector and a threshold unit, a first pulse shaper and a sequence of connected logic block and a defect recorder, TL and -. By the fact that, in order to improve the accuracy and reliability of the control, it is equipped with the second and 5th third pulse shapers, the inputs of which are connected to the output of the first driver, and the outputs to the first and second inputs of the logic unit. Proofreader A.T. sko Subscription