SU828062A1 - Method and device for electromagnetic checking - Google Patents

Description

one

The invention relates to instrumentation engineering and can be used for electromagnetic non-destructive quality control of materials and products.

The phase electromagnetic control method is known, which means that the output signal of the eddy current transducer is amplified, then its phase is measured relative to some reference voltage and the resulting constant voltage is applied to the indicator 1.

However, the known method does not provide the necessary control accuracy.

The closest to the technical essence of the invention is a method of electromagnetic control of the physicomechanical parameters of products, which consists in compensating the output signal of the eddy current transducer, placing the eddy current transducer in the control zone and determining the amplitude of the output signal. In this case, the working point of the eddy current transducer is chosen so that the magnitude of the amplitude of the output signal vector does not depend on the variations of the suppressed parameter.

A device for carrying out a known method comprises a generator connected in series, an eddy current transducer with a compensator, an amplifier, an amplitude detector and an indicator 2.

However, the scope of application of the known method and device for its implementation is limited by the requirements imposed on the shape of the hodographs of the signal introduced into the ECP, which must be (when the amplitude method is implemented, they are close to concentric circles). Because of this, the range of permissible variations of the inhibited parameter is, as a rule, very limited, and, consequently, the reliability and accuracy of measurements are limited.

The aim of the invention is to increase the reliability and accuracy of the control.

This goal is achieved due to the fact that the output signal of the eddy current transducer is compensated before the operating point of the eddy current transducer reaches the center of the homotography hodograph of the output signal of the eddy current transducer depending on the changes in the suppressed parameter before placing the eddy current transducer in the control zone, measuring the signal phase, determining the dependence amplitudes from the phase of the output signal at the nominal value of the monitored parameter and the change in the magnitude of the suppressed parameter, op determine the ratio of the magnitude of the measured signal to the magnitude of the amplitude of the obtained dependence for the measured value of the phase of the signal and the value of the ratio is judged on the monitored parameter. A device for carrying out the method is provided with serially connected phase generator and a phase meter connected to the generator, the second input of which is connected to the output of the amplifier, a storage unit connected to the output of the phase meter, and a ratio measuring unit whose inputs are connected to a storage unit and an amplitude detector, and the output is connected to an indicator .

FIG. 1 shows a block diagram of an apparatus for carrying out the method; in fig. 2 - hodographs of the output signal of the eddy current transducer depending on the changes of the suppressed parameter in relation to the task of measuring the gap (H) regardless of variations in the specific electrical conductivity (Po) of the product.

The device contains a series-connected generator 1, an eddy current transducer 2 with a compensator (not shown), an amplifier 3, an amplitude detector 4 connected to the generator in series by a phase shifter 5 and a phase meter 6, the second input of which is connected to the output of the amplifier 3, the storage unit 7 is connected to the output phase meter 6, the ratio measurement unit 8 with its inputs is connected to the detector 4 and the storage unit 7, and the output to the indicator 9.

The method is carried out as follows.

The signal of the eddy current transducer 2 is compensated depending on the particular problem being solved, for example, in air (see point O of Fig. 2) when measuring the size of the gap regardless of the electrical conductivity of the material of the product, or above the product of the coating material when it comes to controlling the thickness of the electrically conductive coatings on an electrically conductive base. In this case, the operating point of the converter falls into the homothety center of the hodographs of the output VTP signal, depending on the changes in the suppressed parameter.

Then, taking, for example, in relation to solving the problem of measuring the thickness of dielectric coatings on an electrically conductive base (Fig. 2) for the nominal value of the monitored parameter of the gap (I 07 in Fig. 2), the dependence of the amplitude on the phase of the output signal (t / u, i) The RPV of the nominal value (I 0.7) of the monitored parameter and the change in the magnitude (| 3 °) of the suppressed parameter. Remember this addiction. After that install the converter on the controlled product.

Generator 1 is flooded with converter 2 with a compensator. The output voltage of this unit through the amplifier 3, where the scale conversion takes place, is fed to the inputs of the amplitude detector 4 and the phase meter 6. The reference voltage to the phase meter 6 is fed through the phase shifter 5 from the generator 1.

A signal from the output of phase meter 6, proportional to the phase of the output voltage of converter 2 and compensator, is fed to the input of storage unit 7 (whose amplitude characteristic has the form coinciding with the dependence of amplitude on the phase of the output signal of the eddy current converter when the suppressed parameter changes for the nominal value of the monitored parameter) . The voltage from the output of the storage unit 7 is applied to one of the inputs of the ratio measurement unit 8, to the other input of which the voltage from the output of the amplitude detector 4 is proportional to the amplitude of the output signal of the eddy current converter 2 with a compensator. A signal from the output of the voltage ratio measurement unit 8, depending only on the value of the monitored parameter, is fed to the indicator 9.

From the ratio obtained, the value of the controlled parameter is determined. At 0, the error in determining the monitored parameter H does not exceed 0.5% in the range of changes in the suppressed parameter from 0.5 to 1000.

Claims (2)

1. A method of electromagnetic control of physicomechanical parameters of products, which consists in compensating the output signal of the eddy current transducer, placing the eddy current transducer in the control zone and determining the amplitude of the output signal, characterized in that, in order to improve the reliability and accuracy of control, the output the signal of the eddy current transducer is compensated until the operating point of the eddy current transducer falls into the center of the homotography hodograph of the output signal of the eddy current transducer depending on changes in the suppressed parameter before placing the eddy current transducer in the control zone, measure the signal phase, determine the amplitude dependence on the output signal phase at the nominal value of the monitored parameter and change the suppressed parameter value, determine the ratio of the amplitude of the measured signal to the amplitude value on the resulting dependence when measured the value of the phase of the signal and the magnitude of the ratio is judged on the controlled parameter. 2. An apparatus for carrying out the method of claim 1, comprising a series-connected generator, an eddy current transducer with a compensator, an amplifier, an amplitude detector and an indicator, characterized in that it is equipped with a series-connected phase shifter and a phase meter connected to the generator, the second input of which is connected to the output of the amplifier , a storage unit connected to the phase meter output, and a ratio measurement unit, the inputs of which are connected to the storage unit and the amplitude detector, and the output connection with indicator. Sources of information taken into account in the examination 1. Instruments for non-destructive control of materials and products. Ed. V. V. Klyuev. M., Mashchinostroenie, 1976, Vol. 2, s. 126-127. 2. Instruments for non-destructive control of materials and products. Ed. V. V. Klyuev. M., Mashchinostroenie, 1976, Vol. 2, s. 128-130 (prototype).