SU1732254A1 - Device for electromagnetic checking - Google Patents

Abstract

The invention relates to non-destructive quality control of products by electromagnetic methods and can be used to detect defects in a conductive body. The purpose of the invention is to increase the sensitivity to a defect by changing the phase of the reference voltage during the control process. The generator 1 creates in the eddy current transducer (VTP) 2 a variable field. In setup mode, a reference part is placed in the VTP 2. The output voltage of the VTP 2 is amplified by the amplifier 3. By changing the parameters of the phase shifter 5, a zero voltage is set at the output of the first phase detector 4. By changing the parameters of the controlled phase shifter 6, the voltage at the output of the second phase detector 7 is set. . If there is a defect, a non-zero voltage appears at the output of the first phase detector 4, which changes the parameters of the controlled phase shifter 6. The second phase detector 7 measures the phase angle between two voltages, the phase of each of which depends on the parameter being monitored. The indicator 8 indicates the value of the monitored parameter, 1 Il. fe

Description

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CO hO Yu SL

The invention relates to non-destructive quality control of products by electromagnetic methods and can be used, for example, to detect defects in a conductive body.

A device for electromagnetic control is known, comprising a generator, a sensor, an amplifier, an amplitude detector and an indicator connected in series. The device allows monitoring the parameters of products in a contactless manner.

However, the device has low noise immunity, since it implements an amplitude method of extracting information.

It is also known a device for electromagnetic control, comprising a generator, in an oscillating circuit of which an eddy current transducer, detector, indicator is included.

This device is simple to implement and configure, but it has low stability and sensitivity.

Closest to the present invention is an electromagnetic control device comprising a series-connected generator, sensor, amplifier, phase detector and indicator, as well as a phase shifter, the input of which is connected to the output of the generator.

This device has a higher noise immunity, as it implements a phase method of extracting information. The disadvantage of the device is low sensitivity to changes in the monitored parameter.

The aim of the invention is to increase the sensitivity to a change in the monitored parameter by changing the phase of the reference voltage during the control process.

This goal is achieved by the fact that in a known device comprising a generator, eddy current transducer (VTP), an amplifier, a first phase detector, a phase shifter, an indicator, the generator is connected to the ETP moves and a phase shifter whose output is connected to the first input of the first phase detector which is connected to the output of the amplifier, the output of the VTP is connected to the input of the amplifier, additionally equipped with a controlled phase shifter and a second phase detector, the output of which is connected to the input of the indicator, the output of the amplifier dinene with the first input of the second phase detector, the output of the controlled phase shifter is connected to the second input of the second phase detector, the output of the first phase detector is connected to the control input of the controlled phase shifter, and the generator is connected with the second input of the controlled phase shifter.

Introduction to device controlled

the phase shifter, the second phase detector and their interrelation with the units of the device allows the phase of the reference voltage to change during the monitoring process. As a consequence, the phase shift angle between the ETP output signal and the reference signal is larger than in the case of a constant reference voltage phase. This makes it possible to increase the sensitivity of the output signal of the device to a change in the monitored parameter.

The drawing shows a block diagram of the device.

The device for electromagnetic control contains a harmonic oscillator 1, VTP 2, an amplifier 3, a first phase detector 4, a phase shifter 5, a controlled phase shifter 6, a second phase detector 7, an indicator 8. The output of the generator 1 is connected to the inputs of the VTP, phase shifter 5, controlled phase shifter 6 output

VTP 2 is connected to the input of the amplifier 3, the output of which is connected to the first inputs of the first 4 and second 7 phase detectors, to the second input of the first phase detector

4 is connected to the output of the phase shifter 5, the output of the first phase detector 4 is connected

to the control input of the controlled phase shifter 6, the output of which is connected to the second input of the second phase detector 7, the output of which is connected to the input of the indicator 8.

The device works as follows.

Generator 1 creates a harmonic electromagnetic field in the ECT 2. In the setup mode, a reference part is placed in the VTP 2, and the input voltage is applied at the VTP 2 output. This voltage is amplified by amplifier 3 and fed to the first input of the first phase detector 4. To the second input of the first phase detector 4, a phase shifted phase shifter is applied

5 voltage from generator 1. Manually change parameters of phase shifter 5 (change

values of resistors or capacitors), set the zero voltage at the output of the first phase detector 4. Thus, the voltage supplied to the control input of the controlled phase shifter 6 becomes equal to 0. Change the parameters of the controlled phase rotator 6 manually (for example, changing the capacitance of the variable capacitor), a zero voltage is set at the output of the second phase detector 7. The latter measures the shear angle

between the amplified signal from the VTP output and the reference voltage.

In the control mode, the part to be inspected is placed in the ECT 2. If the parameters of this part differ from the parameters of the part being monitored, the phase of the ETS output signal changes. This leads to the appearance of a non-zero voltage at the output of the first phase detector 4, which changes the parameters of the controlled phase generator 6. Thus, the second phase detector 7 measures the phase angle between two harmonic signals, the phase of each of which depends on the monitored signal. The parameter, i.e., the parameter being monitored, changes both the phase of the signal from the ETP output and the phase of the reference signal. If, in this case, the phase increment has a different sign, then the voltage at the output of the second phase detector 7 exceeds the voltage at the output of the first phase detector 4 with the same transmission coefficients of the detectors. This means that the sensitivity of the device signal (output of element 7) to changes in the monitored parameter has increased. Indicator 8 indicates the value of the monitored parameter.

Claims (1)

Invention Formula An electromagnetic control device comprising a generator, a vortex converter, an amplifier, a first phase detector, a phase shifter and an indicator, a generator connected to the inputs of the eddy current converter and a phase shifter, the output of which is connected to the first input of the first phase detector, the second input of which is connected to the output the amplifier, the output of the eddy current transducer is connected to the input of the amplifier, characterized in that, in order to increase the sensitivity, it is equipped with a controllable phase shifter and a second phase The detector, whose output is connected to the indicator input, the amplifier output is connected to the first input of the second phase detector, the output of the controlled phase shifter is connected to the second input of the amplifier, the output of the first phase detector is connected to the control input of the controlled phase shifter, and the generator is connected to the second input of the control phase shifter.