RU1778672C - Method for calibrating and checking pulsating magnetic inspection devices - Google Patents

Abstract

The invention relates to the field of non-destructive testing, in particular to metrological support of pulsed magnetic control. The purpose is to increase calibration accuracy by taking into account the distribution of the gradient of the field strength of the remanent magnetization along the magnetized section. Storing N values of the gradient of the field of remanent magnetization measured along the magnetized section in static, sequential reading with the frequency of the stored values and converting them into current, which feed the measure of the gradient of the magnetic field, allows you to simulate the effects on the primary transducer of the calibrated gradient control magnetic field strengths, similar to the effect of a magnetic field gradient from a magnetized portion of a controlled object during its movement. 1 ill.

Description

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The invention relates to the field of non-destructive testing, in particular to metrological support of pulsed magnetic control.

A known method for calibrating and calibrating pulsed devices for magnetic control 1 is that. measure the amplitude and duration of the magnetizing pulses of the device, simulate the field of remanent magnetization of magnetic marks on the monitored object with a field of measure, and measure the effect of this field on the primary converter of the device.

A known method of calibration and verification of pulse devices for magnetic control 2, which consists in measuring the amplitude and duration of the magnetizing pulses of the device, simulate

the field of the residual magnetization of magnetic marks on the object being monitored by the field of measure and measure the effect of this field on the primary measuring transducer of the device, as a measure use two pulsed magnetic fields directed along the common axis symmetrically towards each other and calibrated in amplitude and duration, the frequency of these pulse fields chosen equal to the frequency of the magnetizing pulses, and their duration m is chosen from the condition

I

+ t.

where I is the length of the magnetized section when measured in statics;

v is the speed of movement of the controlled object;

t-duration of magnetizing pulses.

A disadvantage of the known method is the low accuracy of the calibration simulating the high speeds of movement of the test object due to the fact that the shape of the modeled distribution of the gradient of the field of the remanent magnetization along the magnetized section is not taken into account.

The aim of the invention is to increase the accuracy of calibration by taking into account the distribution of the gradient of the field strength of the remanent magnetization along the magnetized section.

This goal is achieved by measuring the amplitude and duration of the magnetizing pulses of the device being verified, simulating the field of remanent magnetization along the magnetized section with a field of measure and measuring the effect of this field on the primary transducer of the device being verified, using two pulsed magnetic fields as the field directed along the common axis of symmetry towards each other and calibrated in amplitude and duration, the frequency of these pulsed fields is chosen equal to the magnetization frequency ivayuschih impulses and their duration is chosen from the condition r - + t,

where I is the length of the magnetized section when measured in statics;

v is the speed of movement of the controlled object;

t is the duration of the magnetizing pulses,

additionally remember N values of the gradient of the field strength of the remanent magnetization measured along the magnetized section in static, N N

accurately read with a frequency f,. .

I-v vt

stored values of the gradient of the field of the remanent magnetization and convert them into a current, which feed the measure of the gradient of the magnetic field.

The drawing shows a structural diagram of one embodiment of a device for implementing the method.

The device consists of a calibrated induction coil 1 connected to an integrator 2 connected to a pulse voltmeter 3 and a pulse meter 4, connected in series to a controlled pulse generator 5, a pulse counter 6, and a programmable read-only memory

(PROM) 7, digital-to-analog converter (DAC) 8, converter 9 voltage - current and measures 10 of the magnetic field gradient, and the installation input of the counter 6

pulses are connected to the output of the integrator 2, and its output with the blocking input of the controlled pulse generator 5.

The method is carried out as follows.

Insert one of the magnetizing coils of the verified pulsed magnetic control means into a calibrated coil 1 and measure the amplitude with a pulse voltmeter 3, and with a meter 4

duration of pulses the duration of the pulse taken from the integrator 2, which is proportional to the duration and amplitude of the magnetizing pulse. Set magnetically sensitive

elements of the verified means of pulsed magnetic control in the working areas of the measure 10 of the magnetic field gradient. Set the frequency of generation of the controlled generator 5 equal to f TTG.

where N is the number of stored values of the gradient of the field of remanent magnetization.

v is the speed of movement of the controlled object;

I is the length of the magnetized section when measured in statics;

t - the duration of the magnetizing them: pulses.

According to the signal taken from the integrator 2, the pulse counter b is set to its original state and unlocks the controlled pulse generator 5. Output pulses of the controlled generator 5

arrive at the counting input of the counter b pulses. The output code of the counter, which varies in time, is fed to the address inputs of the ROM 7, which stores information about the distribution of the voltage gradient of the remanent magnetization field. The output codes of the EPROM 7 are converted to the corresponding voltage by a digital-to-analog converter (DAC) 8, and the converter 9 voltage is the current in

the corresponding amount of current with which the TO measure is supplied.

Thus, the wire sequential enumeration of the addresses of the ROM 7 in time N v,

, -, and transform it

nor with frequency f

Claims (1)

the output information into the current passing through the measure 10 of the magnetic field gradient forms a magnetic field pulse, the shape of which (in time) is similar to the shape of a pulse from a magnetized portion of a controlled object, which, when the latter moves, acts on the primary transducer (magnetically sensitive element) of the pulse magnetic means being verified control When counter 6 reaches the number N, the latter blocks the controlled oscillator 5, with the arrival of the next magnetizing pulse, the process is repeated. By changing the conversion coefficient of the voltage-current converter 9, a magnetic field pulse of various amplitudes is formed. SUMMARY OF THE INVENTION A method for calibrating and verifying pulse devices for magnetic control, the method comprising measuring the amplitude and duration of magnetizing pulses of a device to be verified, simulating a remanent field along a magnetized area using a measure field, which uses two pulsed magnetic fields directed along the common axis of symmetry towards each other friend and calibrated by 3N amplitude and duration, the frequency of these pulsed fields is chosen equal to the frequency of the magnetizing pulses, and their duration is selected from the condition g-1 +, where I is the length of the magnetized section when measured in statics, v is the speed of movement of the device being verified, t is the duration of the magnetizing pulses, and the effect of this field on the primary converter of the device being tested is measured, characterized in that. in order to increase the calibration accuracy, N values of the gradient of the field of the remanent magnetization measured along the magnetized section in static are stored, the stored values are sequentially read, with a frequency f j, and they convert them into a current, which feed a measure of the gradient of the magnetic field.