SU1465846A1 - Device for measuring residual induction of permanent magnets - Google Patents

Abstract

The invention relates to the field of magnetic measurements and can be used for the production control of permanent magnets of complex shape in an incompletely closed magnetic system. The purpose of the invention is to improve the accuracy of the device by eliminating the negative effect of the demagnetizing field and the inconsistency of the section of the test magnet 1 on the measurement result. The device contains magnetizing coils 2, a source of magnetizing current 3, the first measuring coil 4, integrator 5, comparator 6, recording unit 7, pulse distributor 8, attenuator 9 and integrator 10, forming the second integrator second measuring coil 11, non-magnetic magnet shunt 12 gasket 13 and magneto-conductor 14. Measurement of the residual induction is performed at the moment of equality of the output signals of the integrators 5 and 10. 2 Il. L O) o: el 00 4 a

Description

The invention relates to magnetic measurements and can be used for the production control of permanent magnets of complex shape in an incompletely closed magnetic system,.

The purpose of the invention is to improve the accuracy of the device by eliminating the negative effect of the demagnetizing field and the inconsistency of the section of the test magnet on the measurement result j.

I Fig. 1 shows the functional diagram of the proposed device; I in FIG. 2 - time diagram of the operation of the pulse distributor.

A device for measuring the residual induction of the magnet I contains an incompletely closed magnetic system with magnetizing coils 2, a reversible source 3 of the magnetizing current, the measuring coil 4, the first integrator 5, the comparator 6, the recording unit 7, the distributor 8 pulses, the second integrator in the form of an I attenuator 9 and an integrating amplifier 10, a second measuring coil i 11, a magnetically strong gaunt 12 and a non-magnetic pad 13. In the device, the test permanent magnet 1 I is placed in the working space of an incompletely fixed of the whip magnetic system containing magnetizing EI of coil 2, shunt 12, gasket 13 and magnetic circuit 14, Measuring I coil D, connected to the input of integrator 5, is installed on the test permanent magnet 1, Cat1: 4 and 11, attenuator 9, integrator 5 and amplifier 10 form an induction sensor. Coils 2 are located on the magnetic core 14. Attenuator 9 and the integrating amplifier 10 form an integrator 15.

The device works as follows.

The demagnetized permanent magnet 1 under test is placed in a non-magnetic gasket 13 and placed in the cavity of the shunt 12, which is installed in the working space of an incompletely closed magnetic system between the coils 2. Before measuring, the attenuator conversion distortion coefficient 9 is set to

1C “-

 Sgwa

where S is the area of the neutral section of the test permanent magnet 1;

W is the number of turns of the measuring catupzhi 4; Sg is the area of the test subject of a permanent magnet at the location of the measuring coil 1 I;

Wg is the number of turns of the measuring coil 11. The input signal level of the amplifier 10 is reduced to the input signal level of the integrator 5 at the same rate of change of induction in the test permanent magnet. Before switching on the source current 3, the output voltages of the integrators 5 and 10 are zero. At the output of the comparator 6, to the inputs of which the output voltages of the integrator 5 and the amplifier 10 are applied, a high voltage level is established. The output voltage of the comparator 6 switches the digital distributor 8, at the first output of which a short voltage pulse is formed, resetting and triggering the integrator 5 and the amplifier 10,

The test permanent magnet 1 is magnetized in the gap of the magnetic system until the saturation state. In the subsequent process of weakening the magnetic field, the state of residual induction of the test permanent magnet 1 is reached. The output voltage of the integrator 5 is again equal to the output voltage of the amplifier 10, since induction in the planes covered by the measuring coils 4 and I, have the same value, equal to the value of the residual induction of the material of the wearingtable permanent magnet 1, At the output of the comparator 6 ivaets high voltage level, which leads to the second switching distributor 8. The first output distributor re-formed voltage pulse that sets the integrator 5 and the amplifier 10 to the zero state and initiating their integration mode. By further magnetization of the test permanent magnet 1 along the limiting loop of magnetic hysteresis, a state of residual induction of the material of the test permanent magnet 1 s is obtained.

3U65846

opposite direction of magnetization. At the same time, the output voltages of the integrator 5 and the amplifier 10 are equal, a high voltage level is set at the output of the comparator 6, which leads to the third switching of the distributor 8, at the second output of which a voltage pulse is generated, to the switching unit 7B registration mode the output voltage of the integrator 5, which is proportional to the residual induction of the test permanent magnet 1. The value of the residual induction of the test magnet 1 is determined according to the expression dB,

ten

25

that the magnetic field strength in the air gap is numerically equal to the residual magnetization of the test permanent magnet.

Due to the fact that the poles of the magnetic system are made of a magnetic material and are equipotential surfaces, the magnetic voltage applied to the working volume of the magnetic system has the same value for all power lines. To perform equation (3), it is necessary that the totalizer

15, the length of the power line in the non-magnetic gaps of the magnetic system was the same for all the power lines crossing the test permanent magnet 1. This is achieved by installing a shunt 12 made of a magnetically soft material. If equation (3) is fulfilled in the magnetic system, the residual induction state of the test permanent mold 1, having a complex shape, is determined by the same values of the measured induction in their neutral section and in the volume near the pole, as equal induction values in the entire volume of magnet 1 located in. incompletely closed magnetic system, possible only in the state of residual induction. In other states, the field in the volume of magnet 1 is non-uniform. The occurrence of a magnetic voltage on the pole surfaces, created by the magnetization of the permanent magnet 1, leads to the appearance of a scattering flux from the side surface closing through the shunt 12, and the applied magnetic voltage created by the ppm. a magnetic system results in the appearance of a scattering flux that closes the poles of the magnetic system.

Thus, the proposed device makes it possible to accurately fix the state of residual induction of the test magnet, regardless of its shape.

thirty

35

 2SoWo

where a is the value of the value measured by block 7.

The shape and dimensions of the shunt 12 are obtained when building a picture of the magnetization field of the test permanent magnet 1 placed in the working space of the magnetic system. The constructions are carried out subject to the condition of the same total length of each power line crossing the permanent magnet 1 in nonmagnetic gaps. The non-magnetic gasket 13 fills the space between the test permanent magnet 1. and shunt 12. Its purpose is to firmly fix the non-magnetic gap between the test permanent magnet 1 and shunt 12. At the same time, the permanent magnet I, having a complex shape, is in the state residual induction in an incompletely closed magnetic system, when there is no magnetic voltage between the polar surfaces of the dc magnet 1. This condition is satisfied when

m, G5 „- 0. 3)

where M is the residual magnetization of the test 5) permanent magnet 1;

215 d - the total length of the power line in the air gaps of the magnetic system №1; magnetic stress between

the poles of the magnetic system. one . Equation measuring device From equation (3) it follows that the magnetized exact induction of permanent magnets, the voltage between the poles containing the source of the magnetizing magnetic system V. must be current connected to the magnetizing coils of the magnetic system , air-gap sensor provided, induction, comparator and register 40

45

50

Claims (2)

Invention Formula 0 five that the magnetic field strength in the air gap is numerically equal to the residual magnetization of the test permanent magnet. Due to the fact that the poles of the magnetic system are made of a magnetic material and are equipotential surfaces, the magnetic voltage applied to the working volume of the magnetic system has the same value for all power lines. To perform equation (3), it is necessary that the totalizer 5, the length of the power line in the non-magnetic gaps of the magnetic system was identical for all the lines of force crossing the test permanent magnet 1. This is achieved by installing shunt 12 made of magnetically soft material. If equation (3) is fulfilled in the magnetic system, the residual induction state of the test permanent mold 1, having a complex shape, is determined by the same values of the measured induction in their neutral section and in the volume near the pole, as equal induction values in the entire volume of magnet 1 located in. incompletely closed magnetic system, possible only in the state of residual induction. In other states, the field in the volume of magnet 1 is non-uniform. The occurrence of a magnetic voltage on the pole surfaces, created by the magnetization of the permanent magnet 1, leads to the appearance of a scattering flux from the side surface closing through the shunt 12, and the applied magnetic voltage created by the ppm. a magnetic system results in the appearance of a scattering flux that closes the poles of the magnetic system. Thus, the proposed device makes it possible to accurately fix the state of residual induction of the test magnet, regardless of its shape. 0 five 0 five 0 Invention Formula radios otpichaushsya the fact that, in order to improve accuracy, OIO is equipped with a pulse distributor, and the induction sensor is made in the form of two measuring coils located in the central part of the interband gap and at the pole of the magnetic system and connected to the inputs of the first and second integrators connected to the inputs of a comparator, the output of which is connected to the input of the distribution of pulses, the first and second: swarm of the outputs of which are connected respectively to the combined inputs of the reset of the integrators and the input of the synchronous ation unit registration, information input of which is connected to the output of the first integrator, 2. The device according to claim 1, about tl is that the second integrator is made in the form of a series-connected attenuator and an integrating amplifier, and the magnetic system is made in the form of a magnetic conductor, on which are placed two coaxial magnetically shaking coils the gasket located between the magnetizing coils and the magnet of the soft tongue placed on the surface of the non-magnetic gasket. t / in 1 UBtfiK. g ig.2 .- / || igea 1