SU915029A1 - Device for determination of dynamic magnetization curve of ferromagnetic materials - Google Patents

Description

The invention relates to the field of magnetic measurements and can be used to determine the magnetic characteristics of ferromagnets, as well as for non-destructive testing of ferromagnetic materials and products.

A device for determining the magnetization curve of magnetic materials, containing a source of magnetizing current, made in the form of a potentiometer, the brush of which is driven by a motor through an electromagnetic clutch, with a power source, a switching device with a control circuit consisting of a multivibrator, a key and a counter, a power amplifier, the test sample with magnetizing and measuring windings, the block settings, which is a multi-divider; stabilized source of voltage comparison circuit, made in the form of a null organ, flow meter, connected2

with a measuring winding of a sample through a key and a divider "into two", a magnetic field strength meter, a voltage converter into a digital code and a recorder of measured values [1].

The disadvantage of this device is the low accuracy of determining the dynamic magnetization curve.

A device for determining the magnetization curve, containing a generator for changing the magnetic flux, is a shaped constant-current ring potentiometer with a midpoint, the slider of which can be moved by a reversible DC motor, the sample measuring and magnetizing coils, and an integrating amplifier in the form of a photoelectric fluxmeter to measure the magnetic flux increment , integrated DC amplifier, power amplifier, calibrated resistance> 91502

percussion and two-coordinate recording device [2].

However, this device does not allow ⁴ · em to determine with high accuracy the values of the dynamic magneto-curve. $ niching, as it is intended for testing ferromaterials in permanent magnetic fields,

The closest to the proposed technical solution is a device containing a master oscillator that produces a sinusoidal voltage with a frequency of 500 Hz, which is fed to a frequency divider with a division factor of 10. Its ₅ pulses from the frequency divider synchronize the blocking * oscillator tuned to a frequency of 10 Hz , the output pulses of which are fed to the sawtooth generator. On the _m modulator-generator, a sinusoidal voltage is applied with a frequency of 50 Hz from the master oscillator and a sawtooth voltage with a frequency of 10 Hz. From the output of the modulator-current generator modulated according to the law of "saw" voltage is removed. This voltage is applied to the magnetizing winding of the test sample.

From the resistor in the magnetizing winding circuit, a voltage proportional to the sample magnetization is fed through an amplifier to the horizontal plates of an electron-beam oscilloscope. The sample sample winding is loaded onto an integrator, the output voltage of which is proportional to the induction in the sample and a black amplifier is fed to the vertical plates of the oscilloscope, on the screen of which there is a series of private hysteresis loops arranged one inside the other. To illuminate the vertices of the hysteresis loops and obtain the induction curve for voltage points, taken from the integrator resistor, is fed to the mixer, to the second input of which a sawtooth voltage is also applied. From the output of the mixer, sharp voltage peaks are applied to the control electrode of the 13D oscilloscope. .

However, this device does not allow, with high accuracy, to determine the values of the dynamic magnetization curve of ferromagnets, since the measurement result depends on the subjective qualities of the operator, since it is used as an indicator.

enjoys an electron beam oscilloscope. In addition, the use of an amplitude-modulated signal for the formation of control pulses leads to a significant error in determining the points of the dynamic magnetization curve in its initial part, when the value of intensity and induction are small. These errors increase as the maximum amplitude of the magnetizing field decreases.

The purpose of the invention is to improve the accuracy of determining the values of the dynamic magnetization curve in a wide range of frequencies and amplitudes of magnetizing fields, in particular, in the region of low values of induction and intensity.

This goal is achieved by the fact that the device containing the source of amplitude-modulated oscillations, consisting of a series-connected high-frequency generator, pulse shaper, frequency divider, sawtooth generator and balanced modulator, the second input of the balanced modulator connected to the high-frequency generator, the magnetizing winding series-connected reference resistor and connected to the output of the source of amplitude-modulated oscillations, measuring winding, with of the connections to the input of the integrator, and an indicator incorporated shaper strobe, pulse, first and second strobe converters, signal inputs of which are respectively connected to the output of the integrator and exemplary resistor control inputs through shaper strobe pulses are connected to the output of the generator of high frequency amplitude source ⁴⁵ 1NO modulated fluctuations, and their outputs are connected to the indicator.

The drawing shows a functional diagram of the device.

An apparatus for determining Din ⁵⁰ nomic magnetization curve contains the test sample 1, a source 2, an amplitude-modulated waves, consisting of successive ¹ but connected generator 3 5 * high frequency pulse generator 4, the frequency divider 5, the sawtooth generator 6 and the balanced modulator 7 "and the second

five

the input of the balanced modulator 7 is connected to a high-frequency generator 3, a magnetizing winding 8 with a series-connected exemplary resistor 9 "measuring winding 10 connected to the integrator input 11, the first 12 and second 13 stroboscopic converters. The signal input of the first stroboscopic converter 12 is connected to the integrator output 11, and the signal input of the second stroboscopic converter 13 is connected to the reference resistor 9. The control inputs of the stroboscopic converters 12 and 13 are connected via the driver of the strobe pulses 14 to the generator 3, and their outputs are connected with the indicator 15 ·

The device works as follows.

The test sample 1 is re-magnetized in an alternating magnetic field created by the source 2 of amplitude-modulated oscillations, consisting of a high-frequency generator 3, generating a sinusoidal signal with a frequency of, for example 500 Hz, a driver of 4 pulses, which converts this signal into rectangular pulses following this 500 Hz frequency, divider 5 frequency with a division factor, for example 50, at the output of which rectangular pulses with a repetition frequency of 10 Hz are formed, these pulses are fed to the input of the generator 6 saws About the shape of the voltage from the output of which the sawtooth signal is fed to one of the inputs of the balanced modulator 7, and the second input receives the voltage from the generator 3 high frequency. The balance modulator 7 directly multiplies the incoming signals at its inputs. The source of 2 amplitude-modulated oscillations serves as a magnetizing winding Ι8 with a series-connected exemplary resistor 9 · The measuring winding 10 of the test sample 1 is connected to the integrator 11, the output voltage of which is proportional to induction B () in the sample.

By using the amplitude-modulated signal ⁵⁵ Rowan as magnetizing current, the magnetic state of the sample 1 for a frequency change

915029 6

hysteresis loops located one inside the other.

Shaper pulse generator 14. Made, for example, in the form of ₅ series-connected phase shifters, null organ and standby multivibrator produces pulses of duration, for example, 1-10 μs at the times corresponding to the maximum field strength.

for each private hysteresis loop These pulses control the operation of a stroboscopic converters 12 and 13. At a signal input stroboscope ₁₅ Cesky converter 12 receives a signal proportional to the instantaneous values of the induction time in {¢), and the signal input 13 of the stroboscopic converter ₂₀ is supplied with a signal model resistor 9 "proportional to the instantaneous values of the intensity H (¢). At the outputs of stroboscopic converters 12 and 13, made, for example, in ₂₅ types of blocks of sampling and storing analog signals, signals are generated that are proportional to the instantaneous values of induction V _t and maximum intensity N _t for each particular hysteresis cycle, respectively. Thus, at the outputs I of stroboscopic transducers 12 and 13, DC voltages take place, which are proportional, respectively, and! ·% ;, which are fixed during the time between two strobe pulses on the two-channel indicator 15.

The proposed device allows numerically obtaining direct values of a dynamic magnetization curve in a wide range of variation of the magnetizing field parameters with high accuracy and speed, and the required number of dynamic curve values can be changed by varying the parameters of the magnetizing field, for example, by changing the carrier ratio (high) and modulating (sawtooth) frequencies.

Claims (1)

Claim A device for determining the dynamic magnetization curve of ferromagnetic materials, containing amplitude modulated source Ί 915029 8 oscillations consisting of a series-connected high-frequency generator, a pulse shaper, a frequency divider, a sawtooth generator, and a balanced 5 r0 modulator, the second input of the balanced modulator connected to the high frequency generator, the magnetizing winding with a series-connected exemplary resistor and connected to the output of the amp source * 'loud-modulated oscillation measuring winding connected to the integrator's input, and an indicator, characterized in that, with <5 to improve the accuracy and measuring administered it shaper strobe pulses, the first and second stroboscopic transducers, the signal inputs of which are connected respectively to the output of the integrator and the exemplary resistor, the control inputs through the shaper of the gating pulses are connected to the output of the high-frequency generator of the source of amplitude-modulated oscillations, and their outputs are connected to the indicator. .