SU930178A1

SU930178A1 - Magnetic flaw detector

Info

Publication number: SU930178A1
Application number: SU792865598A
Authority: SU
Inventors: Владимир Дмитриевич Грибанов; Борис Иванович Киселев; Владимир Павлович Шмелев
Original assignee: за вители
Priority date: 1979-11-26
Filing date: 1979-11-26
Publication date: 1982-05-23

Description

Изобретение относится к измерительной технике и может быть использовано для контроля качества магнитной ленты при ее производстве или эксплуатации.The invention relates to measuring equipment and can be used to control the quality of a magnetic tape during its production or operation.

Известен магнитный дефектоскоп,ра- $ ботающий в режиме автогенерации, который содержит индикатор, усилитель, охваченный положительной обратной связью. К выходу усилителя подсоединена первичная обмотка, а ко входу - ₁₀вторичная. Обмотки расположены на разомкнутом магнитопроводе, причем образец помещается в щель магнитопровода. Параллельно вторичной обмотке подключен конденсатор _|5 A known magnetic flaw detector operating in the auto-generation mode, which contains an indicator, an amplifier, covered by positive feedback. The primary winding is connected to the amplifier output, and ₁₀ secondary is connected to the input. The windings are located on an open magnetic circuit, and the sample is placed in the slot of the magnetic circuit. Parallel to the secondary winding connected capacitor _{| 5}

Однако в известном магнитном дефектоскопе зондирующий магнитный поток имеет значительную величину, что не позволяет проводить неразрушающий контроль магнитной пленки, кроме того, из-за взаимного влияния обмоток на высоких частотах точность измерения снижается.However, in a known magnetic flaw detector, the probe magnetic flux is significant, which does not allow non-destructive testing of the magnetic film, in addition, due to the mutual influence of the windings at high frequencies, the measurement accuracy is reduced.

Цель изобретения - повышение точности.The purpose of the invention is improving accuracy.

Поставленная цель достигается тем, что в магнитном дефектоскопе, содержащем индикатор и усилитель, охваченный положительной обратной связью, к выходу которого подключена первичная обмотка, а к входу - вторичная обмотка, параллельно которой подсоединен конденсатор, причем обмотки расположены на разомкнутом магнитопроводе, в щель которого введен образец, первичная обмотка выполнена в виде одного витка из металлической ленты, расположенного поверх вторичной обмотки и подключенного к выходу усилителя через дополнительно введенный токоограничивающий резистор, параллельно которому подсоединен индикатор, при этом усилитель выполнен в виде эмиттерного повторителя.This goal is achieved by the fact that in a magnetic flaw detector containing an indicator and amplifier, covered by positive feedback, the output of which is connected to the primary winding, and to the input is the secondary winding, in parallel with which a capacitor is connected, and the windings are located on an open magnetic circuit, into the slot of which is inserted the sample, the primary winding is made in the form of a single turn of a metal tape located on top of the secondary winding and connected to the output of the amplifier through an additional input current a limiting resistor, in parallel with which an indicator is connected, while the amplifier is made in the form of an emitter follower.

Причем параллельно вторичной об- мотке подсоединен кварцевый резонатор.Moreover, a quartz resonator is connected parallel to the secondary winding.

На чертеже изображена блок-схема предлагаемого магнитного дефектоско· па.The drawing shows a block diagram of the proposed magnetic defect · pa.

Магнитный дефектоскоп содержит магнитный сердечник 1, в зоне которого расположен образец 2, усилитель. 3,к выходу которого подключены параллельно соединенные индикатор 4 и (токоограничивающий резистор 5· Через токоограничивающий резистор 5 к выходу усилителя 3 подключена первичная обмотка 6, выполненная из металлической ленты в виде одного витка, расположенного поверх вторичной обмотки 7. Параллельно вторичной обмотке 7 подсоединен конденсатор 8.A magnetic flaw detector contains a magnetic core 1, in the area of which a sample 2 is located, an amplifier. 3, to the output of which a parallel indicator 4 and is connected (current-limiting resistor 5 · Through the current-limiting resistor 5, the primary winding 6 is connected to the output of the amplifier 3, made of metal tape in the form of a single coil located on top of the secondary winding 7. A capacitor is connected in parallel with the secondary winding 7 8.

) Магнитный дефектоскоп работает следующим образом.) A magnetic flaw detector operates as follows.

Вторичнай обмотка 7 и конденсатор 8 образуют.резонансный контур, на частоте резонанса которого возникают автоколебания при выполнении условий баланса фаз и амплитуд. Баланс фаз достигается переменной концов одной из обмоток 6 и 7, а баланс амплитуд - выбором числа витков вторичной обмотки 7· Усилитель 3 представляет собой эмиттерный повторитель - усилитель мощности. 3 зазоре магнитопровода 1 возникает магнитный поток, проходящий через образец 2. В случае изменения магнитных параметров образца 2, меняются параметры обратной связи, что вызывает изменение амплитуды колебаний, фиксируемое индикатором 4.The secondary winding 7 and the capacitor 8 form a resonant circuit, at the resonance frequency of which self-oscillations occur when the conditions of phase and amplitude balance are satisfied. The phase balance is achieved by the variable ends of one of the windings 6 and 7, and the amplitude balance is achieved by choosing the number of turns of the secondary winding 7. Amplifier 3 is an emitter follower - power amplifier. 3, the gap of the magnetic circuit 1 causes a magnetic flux passing through the sample 2. In the case of a change in the magnetic parameters of the sample 2, the feedback parameters change, which causes a change in the amplitude of oscillations, fixed by indicator 4.

В общем случае возможно некоторое изменение частоты колебаний. Тогда вместо конденсатора 8 необходимо включить кварцевый резонатор, который стабилизирует частоту колебаний дефектоскопа и сделает его нечувстви10In the general case, some change in the frequency of oscillations is possible. Then, instead of the capacitor 8, it is necessary to include a quartz resonator, which stabilizes the oscillation frequency of the flaw detector and makes it insensitive 10

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930178 4 тельным к изменению магнитной проницаемости. В этом случае изменение амплитуды будет происходить за счет диссинации энергии в образце 2.930178 4 to the change in magnetic permeability. In this case, the change in amplitude will occur due to energy dissipation in sample 2.

Применение предлагаемого магнитного дефектоскопа позволяет повысить точность измерений, а также обеспечивает роля возможность неразрушающего контмагнитной ленты.The use of the proposed magnetic flaw detector can improve the accuracy of measurements, and also provides the role of non-destructive magnetic tape.

Claims

The invention relates to a measuring technique and can be used to control the quality of a magnetic tape during its manufacture or operation. A magnetic defectoscope operating in the autogeneration mode is known, which contains an indicator, an amplifier, covered by a positive feedback. A primary winding is connected to the output of the amplifier, and a secondary is connected to the input. The windings are located on an open magnetic circuit, and the sample is placed in the slot of the magnetic circuit. A capacitor l is connected in parallel with the secondary winding. However, in a known magnetic flaw detector, the probing magnetic flux is of considerable magnitude, which does not allow non-destructive testing of the magnetic film, moreover, due to the mutual influence of the windings at high frequencies, the measurement accuracy decreases. The purpose of the invention is to improve accuracy. The goal is achieved by the fact that in a magnetic flaw detector containing an indicator and an amplifier covered by a positive feedback, the output winding is connected to the output, and the secondary winding is connected to the input, parallel to which a capacitor is connected, and the windings are located on the open magnetic circuit, in the slot of which a sample is inserted, the primary winding is made as a single turn of a metal tape located on top of the secondary winding and connected to the output of the amplifier through the additionally introduced oogranichivayuschy resistor, which is connected parallel to the lamp, wherein the amplifier is configured as an emitter follower. Moreover, a quartz resonator is connected parallel to the secondary winding. The drawing shows a block diagram of the proposed magnetic flaw detector. The magnetic flaw detector contains a magnetic core 1, in the zone of which sample 2, the amplifier, is located. 3, the output of which is connected in parallel with the t indicator and the current limiting resistor 5- Through the current limiting resistor 5 to the output of the amplifier 3 is connected the primary winding 6, made of metal tape in the form of one coil located on top of the secondary winding 7. Parallel to the secondary winding 7 of the subconnector 8 h Magnetic flaw detector works as follows. The secondary winding 7 and the capacitor 8 form a resonant circuit, at the resonance frequency of which self-oscillations occur when the conditions of phase and amplitude balance are satisfied. The balance of the phases is reached by the variable ends of one of the windings 6 and 7i and the balance of the amplitudes by selecting the number of turns of the secondary winding 7. Amplifier 3 is an emitter follower - power amplifier. In the gap of the magnetic circuit 1, a magnetic notoK appears, passing through the sample 2. In the case of a change in the magnetic parameters of the sample 2, the feedback parameters change, which causes a change in the amplitude of oscillations, fixed by the indicator A. In general, some variation of the frequency of oscillations is possible. Then, instead of the capacitor 8, it is necessary to include a quartz resonator, which stabilizes the oscillation frequency of the flaw detector and makes it insensitive to changes in magnetic permeability. In this case, the amplitude change will occur due to the energy dissipation in sample 2. The use of the proposed magnetic flaw detector makes it possible to improve the measurement accuracy and also provides the possibility of non-destructive testing of the magnetic tape. 1. Magnetic flaw detector containing an indicator and an amplifier covered by a positive feedback, to the output of which the primary winding is connected, and to the input - the secondary winding, in parallel to which a capacitor is connected, and the windings are located on an open magnetic circuit, into the slot of which a sample is inserted, characterized in that, in order to increase the accuracy, the primary winding is made as a single turn of metal tape located on top of the secondary winding and connected to the output of the amplifier through additionally introduced current limiting resistor, in parallel to which the indicator is connected, and the amplifier is made in the form of an emitter follower.

2. Flaw detector section 1, about t l and due to the fact that a quartz resonator is connected parallel to the secondary winding. Sources of information taken into account in the examination. Leiman A.A. Automatic oscillator magneto-transistor sensors and relays. M., Energie, 1971, p. .