SU1503032A1 - Method of measuring coercion force - Google Patents

Abstract

The invention relates to magnetic measurements and can be used to measure the coercive force of ferromagnetic products. The aim of the invention is to improve the accuracy of measurement of the coercive force. According to the method involving the impact of a constantly increasing alternating sinusoidal magnetic field on the sample, the first harmonic signal of the secondary field is isolated, the phase of the first harmonic signal is measured and the phase of the first harmonic signal is inverted, the corresponding amplitude value of the amplitude H _{M of the} alternating sinusoidal magnetic field is recorded , and the coercive force is determined by the formula H _C = √ H _M. 1 il.

Description

The invention relates to magnetic measurements and can be used to measure the coercive force of ferromagnetic products.

The aim of the invention is to improve the accuracy of measuring the coercive force.

The essence of the method is as follows.

When simultaneously acting on a ferromagnet by alternating sinusoidal H and permanently magnetizing H magnetic fields directed parallel to the boundary surfaces of the controlled product, magnetic induction of a material with a coercive force Hg can be represented as

B I B arctgpaH -t-HpT H);

SA9

About CO 1 hE

Nh sincot,

, one . DVg (r--);

with

B and B - maximum and residual TTLH

on induction of material, respectively.

The amplitude of the first harmonic is determined by the ratio

f fp / a | cosM, sinb) t).

 nPpBoii garns) ravn.ch

h

B,

1 7

where a and b, are the decomposition coefficients of the 5 .ap of the first harmonic

but,

- (psin ((- i-p, sinC |,);

s

- - (nrosif-p, cosCp),

where p, p, - const.

For the field of weak measured fields

ot (H, -H,), (

"In i-gTTT fn /

p.

fucking

co9 (t-cos,

   2H2 | - (H2 + Hp. Thus, the phase of the first harmonic is connected with alternating and constant magnetic fields, depends on the coercive force, and is positive if the inequality is violated, phase reversal, t. E. It changes the sign.

For the case when constant magnetization is missing (), the first harmonic phase is determined by the ratio

one

2n „,

2Н - н W с

In this case, by changing the value of the ac field until the moment of phase reversal, the coercive force is determined from the ratio

HC .- The drawing is structural

The scheme of the device that implements the method of measuring the coercive force when a controlled ferromagnet is influenced by a smoothly increasing alternating sinusoidal magnetic field.

A device that implements the method includes a pass-through converter 1, a selective amplifier 2, an excitation field tuned to the first harmonic, a phase meter 3, a logical switch 4, a generator of sinusoidal current 5, and an indicator 6.

0

0

five

five

0

five

Q

v cTioioMc lo works in the following way.

A sinusoidal current of frequency f, increasing in amplitude, flows through the excitation winding of the through converter 1 from the generator 5. The signal from the measuring winding of converter 1 is fed to a selective amplifier 2, which is tuned to frequency f, as a result of which a sinusoidal EMF with frequency f is generated at the output of selective amplifier 2 and fed to the first input of phase meter 3. the signal of the same frequency f. Thus, the phase meter 3 measures the phase of the first harmonic, the magnitude of which is determined by the properties of the product under test and the magnitude of the excitation field. The current phase values arrive at the logical key 4, which gives a signal to the generator 5 only when the phase is zero, and the indicator 6 records the value of the intensity of the alternating field at that moment. The magnitude of the coercive force is determined from the expression

Claims (1)

c. Formula of Invention The method of measuring the coercive force, including the impact of a sample on an alternating sinusoidal magnetic field, measuring this secondary magnetic field and isolating its harmonic component, characterized in that, in order to increase the measurement accuracy, The first harmonic signal of the secondary field is measured, the phase of the first harmonic signal is measured, the moment of the phase reversal of the first harmonic signal is recorded, and the coercive force H is determined t according to the formula H N, where the amplitude of the tension of the alternating sinusoidal magnetic field at the time of the phase reversal of the signal of the first harmonic of the secondary magnetic field.