SU1420563A1 - Apparatus for inspecting magnetic properties of cores of open shape - Google Patents

Abstract

The invention can be used in determining the magnetic permeability of cores made in the form of plates used, for example, in the manufacture of magnetic heads. A device for monitoring the magnetic properties of open-core cores contains a magnetic circuit (MP) 1 with magnetizing and measuring windings (O) 2 and 3, respectively, MP 4 with a compensation winding 5, controlled core 6 with measuring winding 7, sources 8, 9 AC, flow meter 10, switch 14, voltage divider 18, subtractive blocks 16, 17, indicator 19, collector resistor 21, control block 20, level memory 15, analog switches 11, 12, rectifier 13. The device has an increased performance s and by automating its mode of operation in the measuring cycle, reducing the control algorithm while maintaining its reliability. 3 il.

Description

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The invention relates to magnetic measurements and can be used in determining the magnetic permeability of cores made in the form of plates used, for example, in the manufacture of magnetic heads.

The purpose of the invention is to improve the performance of the device by automating its mode of operation in the measuring cycle, reducing the control algorithm while maintaining its reliability.

FIG. 1 shows a block diagram of the proposed device; in fig. 2 - current source, one of the variants; in fig. 3 - voltage divider, one of the embodiments.

The device contains the first magnetic conductor 1 with magnetizing 2 and measuring 3 windings, the second magnetic conductor 4 with compensation winding 5, the controlled core 6 with the second measuring winding 7, the first 8 and second 9 current sources, the flow meter 10, the first 11 and the second 12 analog switches, rectifier 13, switch 14, level memory unit 15, second 16 and first 17 subtraction units, voltage divider 18, indicator 19, control unit 20 into a removable resistor 21. Measuring winding 7 is connected to a flow meter 10 and through analog A new switch 11 is connected to the control input of source 9. The output of source 8 is connected in series with the magnetizing winding 2 and current-carrying resistor 21, and the output switch of source 9 is connected in series with an analog switch 12 and compensation winding 5. Measuring winding 3 through a rectifier 13 is connected to the input of the switch 14, the first and second outputs of which, respectively, through the level memory unit 15 and the first channel of the divider 18 are connected to the first and second inputs of the subtractive unit 16, the output of which is connected to the control the input of the divider 18. The first input of the subtracting unit 17 is through the second channel of the divider 18, and its second input is directly connected to the collector resistor. The output of the unit 17 is connected to the input of the indicator 19. The outputs of the control unit 20 are connected to the control inputs of the analog switch 12 and the analog switch of the generator 14, and the control input of the analog switch 11 is connected in parallel to the compensation winding 5.

The device works as follows. In the first setup cycle, control unit 20 locks the analog switch 12 and sets switch 14 to the state in which the input signal passes to its first output. When this alternating current with an amplitude of / specified by the current source 8, has flowed through the magnetizing winding 2, creates magnetic fluxes Ф i в

the magnetic circuit 1 and Φ in the controlled core 6. The magnitude of the current is established to ensure the flow Φ F o, which is monitored by the flow meter 10. For a closed magnetic circuit formed by the magnetic core 1, controlled by the core 6 and non-magnetic gaps, the ratio

0

five

five

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35

40

/ F, () + Fo Yap,

(Ij

where W is the number of turns of the winding 2;

/ m is the magnetic resistance of the magnetic circuit 1;

 - the total resistance of the non-magnetic gaps between the core 6 and the magnetic core 1;

Rn is the magnetic resistance of the core 6.

The variable EMF induced in winding 3 is converted by rectifier 13 into a constant voltage level (K - proportionality coefficient), which is fixed by unit 15. In the second measuring cycle, control unit 20 opens analog switch 12 and sets switch 14 to the state when which the input signal passes to its second output. In this case, an alternating current begins to flow in the compensation winding 5, the amplitude of which is set by the current source 9, and the phase coincides with the current phase in the magnetizing winding 2. The magnetic flux in the magnetic core 4, depending on the compensation current value in the winding 5 or is out of phase by 180 ° relative to the flow in the controlled core 6 (with insufficient compensation current), or coincides with it in phase (with a compensation current exceeding that required for no flow in the core 6). Accordingly, the voltage on the compensation winding 5 applied to the control input of the analog switch 11, or is shifted in phase by 180 ° relative to the signal induced in the measuring winding 7, or coincides with it in phase. As a result, an analog switch 11, which is opened during, for example, positive half-periods of voltage variation at 45 winding 5, passes only the positive component of the signal from winding 7 to the control input of current source 9 at a compensation current exceeding that required for no flow in the core 6, and only the negative component of this signal 50, when the compensation current is insufficient.

A positive or negative voltage at the control input of the current source 9 leads, respectively, to a decrease or increase in the compensation current, and in the steady state the compensation current ensures the absence of magnetic flux

controlled core 6. At the same time for a closed loop formed by the first magnetic core 1, the core 6 and the gaps between them, the ratio

()

where f 1 is the new value of the flux in the magnetic circuit 1.

In the steady-state measurement cycle, a constant voltage level from the output of rectifier 13 through the switch 14 and the first channel of the divider 18 is fed to the second input of the second subtracting unit 16, the first input of which records the voltage level Y, / (. F |. Differential signal from the output of block 16, it acts on the control of the input of the divider 18, setting the divider's transmission coefficient on both channels Ka F 1 / F where the output of the subtracting block 16 is zero. reading signal block 17

w / Cn (pf times greater than the second input

this block, and since a signal arrives at the second input (R is the resistance of the collector resistor 21), a differential signal appears at the output of block 17 and, accordingly, at the input of indicator 19

(i-)

From relations (1), (2) it follows that the magnitude of the magnetic resistance of the controlled core is determined by the expression

R -hf. (about 9G

Thus, the input of the indicator 19 receives a signal proportional to the magnitude of the magnetic resistance of the monitored core, and the proportionality coefficient is easily determined from the known) and given (F o) values.

To ensure the operability of the device, current sources 8 and 9 (voltage-current transducers) in the simplest case can be (see Fig. 2) variable resistors 22 () connected to the output of the alternator 23 (for example, GZ-56) at the source 9, the variable resistor slider is rigidly mechanically connected to the rotor of a low-speed DC motor 24 connected to the output of power amplifier 25, the input of which serves as the control input of source 9. Such a circuit provides the sensitivity of the device polarity of the input voltage and fixing the resistance of the resistor 22 at zero

signal at the control input. Divider 18 can be made according to the resistive divider scheme (see Fig. 3) having two identical channels with a dual variable resistor 26 () common to both channels, which is controlled according to the same principle as the source 9, t i.e. using a 24 dc motor and a power amplifier 25. The use of a double variable resistor ensures the same transmission coefficient on both channels when the latter is changed. Block 20 is implemented as switches on the control panel of the device, connecting a current source (for example, a power source of electronic devices used in the device) to the control inputs of the respective blocks.

The use of the proposed device allows increasing productivity.

20 control in comparison with the prototype by fully automating the measuring cycle while retaining all its positive qualities, namely, the independence of the result from the magnetic resistance of the closing

25 of the magnetic circuit, on the magnitude of the non-magnetic gaps and the measurement mode, which allows the device to be used directly in shop conditions, for example, to control the magnetic permeability of magnetic heads plates.

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Claims (1)

Invention Formula A device for monitoring the magnetic properties of open-core cores, containing two magnetic conductors with magnetizing and compensating windings, respectively, two measuring windings placed respectively on the first magnetic conductor and on the controlled core, two AC sources, to the outputs of which are connected and for the first time the outputs are respectively magnetizing and compensation winding, flow meter, the input of which is connected to the first output of the second measuring winding, switch, divider eg and a subtracting unit, the output of which is connected to the indicator input, a collector resistor, the first terminal of which is connected to the second output of the magnetizing winding and the first input of the subtractive unit, and the second output of the collector resistor is connected to the second output of the second measuring winding, the first output of the first measuring winding and a common bus, characterized in that, in order to improve performance, a second subtraction unit, a control unit, a memory unit, two analogue inputs are inserted into it.  key and rectifier, the input of which is connected to the second output of the first measuring winding, and the rectifier output connected to the input of the switch, the first output of which is connected to the input of the unit for level memory, the output of which is connected to the first input of the second subtractive unit, the second input of which is connected to the first output of the voltage divider, the first input of which is connected to the second output of the switch, and the output of the second unit subtracting is connected to the control input of the voltage divider, the first output of the second measuring winding is connected to the control input of the first analog switch, the output of which is connected to the control The second input of the current source, the second output of the compensation winding is connected to the input of the second analog switch, the output of which is connected to the common bus, the input of the first analog switch is connected to the output of the second current source, the first output of the collector resistor is connected to the second input of the voltage divider, the second the output of which is connected to the second input of the first subtraction unit, and the first and second outputs of the control unit are connected respectively to the control inputs of the compiler and the second analog key. Manage) 0sch phage. Compiled by S. Shumilishska Editor S. LisinaTehred I. VeresKorrektor L. Patay Order 4327/52 Circulation 772 Subscription VNIIPI USSR State Committee for Inventions and Discoveries 113035, Moscow, Zh-35, Raushsk nab. 4/5 Production and printing company, Uzhgorod, ul. Project, 4 I -0 fi. $. 2