SU1067346A2 - Dielectric coating thickness meter - Google Patents

Abstract

THICKNESS / ER OF DIELECTRIC COATINGS according to ed. St. 905620, characterized in that, in order to improve the measurement accuracy, the parameters of the eddy current transducer are selected from the following ratios, 3 where Ь, and | 72 is the distance from the exciting and measuring windings to the working end of the eddy current converter, respectively; R J and the radii of the exciting and measuring windings, respectively.

Description

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The invention relates to a reference measurement technique and can be used to measure the thickness of dielectric coatings.

According to the main author. St. LL 905620 is known for tolilimer dielectric coatings containing a series-connected auto-oscillator, an invoice eddy current transducer, a phase-sensitive detector, a reference voltage to which is supplied from the auto-oscillator through a phase shifter, an adder, the second input of which is connected to the output of the eddy current transducer via an amplitude detector and an indicator 1.

However, the measurement accuracy of the known thickness gauge is not optimal, since it essentially depends on the design parameters of the eddy current transducer, and the latter are not defined in the known device.

The purpose of the invention is to increase the accuracy of measurements.

This aim is in thickness meter dielectric coatings containing series-connected oscillator, bill eddy current transducer, a phase sensitive detector, reference voltage which is supplied from the oscillator via a phase shifter, an adder, a second input coupled to an output of the eddy current .preobrazovatel through amplitude detector, and an indicator is achieved due to that the parameters of the eddy current transducer are selected from the following ratios:

0.3. | --- - 0.4,

where hj and h are the distances from the exciting and measuring windings to the working end of the vihrothread converter, respectively; R (and RJ are the radii of the exciting and measuring windings, respectively.

FIG. 1 shows a block diagram of a dielectric coating thickness gauge; in fig. 2 shows a variant of the mutual arrangement of eddy current transformer windings; in fig. 3 - dependences .module 6 of the maximum relative measurement error and the relative amplitude V of the insertion voltage of the eddy current transducer versus the variations of H (h, + hj) / TlR, ranging from 0.1 to 3.0. Thickness of the dielectric coating is composed of series-connected oscillator 1, the applicator eddy current transducer 2, a phase-sensitive detector 3, a reference voltage which is supplied from the oscillator 1 via the phase shifter 4, the adder 5 is connected a second input of the amplitude detector 6 to the eddy current transducer output 2, and the indicator 7. The exciting winding 8 and the measuring winding 9 are arranged in such a way that the ratios are satisfied

where b, b 2, are the distances from the exciting winding 8 and measuring winding 9 to the working end 10 of the eddy current transducer, respectively;

R and Rj are the radii of the exciting winding 8 and measuring winding 9, respectively.

The thickness gauge of the dielectric coatings works as follows.

The auto-oscillator 1 feeds a sinusoidal current to the superimposed eddy current transducer 2. The input voltage from the eddy-current transducer 2 is fed simultaneously to the inputs of the phase-sensitive detector 3 and the amplitude detector 6 and the reference voltage of the phase-sensitive 0 detector 3 using the phase-shifter 4 has been set up to use the phase-response detector 6 and the amplitude detector 6, using the phase-sensitive 0 of the 3, to use the phase-shifter 4 to set the 4 of the amplitude detector 6 through the phase-sensitive 0 of the 3, using the phase shifter 4, to set the 4 of the amplitude detector 6 to the amplitude detector the output voltages of the detectors are summed up in the adder 5, and then fed to the indicator 7.

 The dependence analysis (Fig. 3) shows that the curve a - the dependence of module 6 of maximum relative measurement error has a characteristic break in the area of NOT 0.3; 0.4. The deviation from this area to the left leads to a sharp increase in the measurement error, and to the right to a significant decrease in the amplitude of the output signal of the converter. Thus, with variations of H from 0.3 to 0.1, the measurement error increases by a factor of 2, and when H is changed from 0.4 to 1.2, it practically remains constant (decreases by only 1%).

On the other hand, an increase in H from 0.4 to 1.2 leads to a decrease in the amplitude of the output signal of the converter by more than 3 times.

Thus, an increase in the measurement accuracy due to the shift of the absolute value of H to the region of large values is limited by a significant decrease in the sensitivity of the transducer to the measured value, which makes it difficult to implement the device.

Range of values Hf 0.3; 0.4 is optimal and allows you to ensure measurement accuracy that is sufficiently high for practice without significantly reducing the sensitivity of the converter to the thickness of the dielectric layer.

The error in measuring dielectric coating thickness, for example, up to 1 mm, on a non-ferromagnetic basis does not exceed ± 2%, and on a ferromagnetic basis - ± 3%. The device allows measuring the thickness of the dielectric coating on any electrically conductive base in the same range, but with greater accuracy.

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Claims (1)

THICKNESS METER OF DIELECTRIC COATING according to ed. St. Λ »905620, characterized in that, in order to increase the accuracy of measurements, the eddy current transducer parameters are selected from the following relations ^{0.3 έ} ° ' ⁴ ' where 1ι, and h _{2 are the} distances from the exciting and measuring windings to the working end of the eddy current transducer, respectively; RjH R _{z are the} radii of the exciting and measuring windings, respectively. O <1 SC? σ: