SU1183874A1 - Radiowave meter of metal sheet thickness - Google Patents

Description

The invention relates to a measuring technique and can be used both for stand-alone control and in automatic control systems for the thickness of metal 5 sheets (in particular for measuring the thickness of the rolled sheet) in conditions of high dustiness and gas pollution of the air, with a large range of temperature and humidity measurement .

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

FIG. 1 shows a block diagram of a radio wave> 5 gauge of the thickness of a metal sheet; in fig. 2 - design of sensitive elements.

The radio wave thickness gauge of a metal sheet contains a microwave generator of variable frequency 1, trigger unit 2, tee 3, first sensitive element 4, made in the form of a C-shaped waveguide, first detector 5, first generator 25 25 pulses, first trigger 7, first integrator 8, second sensitive element 9, identical to the first, second detector 10, second driver 11 pulses, second 30

trigger 12, the second integrator 13, the first adder 14, the multiplier 15, the second 16 and the third 1? adders.

Radio wave meter thickness gauge metal sheet works as follows.

Frequency-modulated high-frequency oscillations from the microwave generator 1 through the tee 3 enter the first and second sensing elements 4 and 9. On the first and second detectors 5 and 10 resonant pulses are formed, the first and second triggers 7 and 12 are generated in the pulse shaper zero sos-45 The first and second triggers 7 and 12 are brought into one state simultaneously with the launch of the microwave generator 1 by applying a pulse from the start block 2. 50

The residence time of the first and second triggers 7 and 12 in a single state (hence the voltage at the output of the first and second integrators 8 and 13) is proportional to the frequency (the thickness of the sheet). And on. the output of the first integrator 8 voltage depends on the thickness of the investigated metal sheet 18 and disturbances. This voltage through the informative parameter can be represented as

and ~ (£ + D £) / x / 0

At the output of the second integrator 13, the voltage depends only on disturbing influences.

and ~ (£ + & £) / х ϊ 0

At the output of the first adder 14, the voltage is proportional to ~ £, and at the output of the second adder 16, the voltage depends only on the disturbing influences i £ ₀ . At the output of the multiplier 15, the voltage is ϋ ~ Έ Λ £ _θ K. At the output of the third adder 17 ", the voltage is proportional to the thickness of the investigated metal sheet 18 (and l. X).

With a known frequency range of the microwave generator 1, the length of the C-shaped waveguide is selected from the following considerations

p ₌ 'λ _in (x, + x ₂ )

2 δα ’

where 71 ₆ - Wavelength in the C-shaped segment of the waveguide;

x ^ them ₂ ~ distances to the studied metal sheet 18.

The output characteristic of the sensitive element 4 or 9 in the form of a C-shaped waveguide segment can be viewed as the dependence of the resonant frequency on its length x, x _, or x (Fig. 2)

_£ = _1_ ₊ kS ¹

^οη Ρ 4ε ¹ V a ² (L + x) ²

where a is the size of the wide wall of the C-shaped segment of the waveguide;

L is the length of the C-shaped segment of the waveguide;

x is the distance from the open end to the surface of the studied metal sheet 18;

£ is the dielectric constant of the medium filling the C-shaped section of the waveguide;

K, K ₂ - constant coefficients,

determined by the medium filling the C-shaped segment of the waveguide.

1 183874

phage. one

Claims (2)

RADIO WAVE METER SHEET THICKNESS meter containing a microwave generator of varying frequency, the start input of which is connected to the output of the start block, and the output shoulder of the tee is connected to the output, the first sensitive element made in the form of a C-shaped waveguide, the input of which is connected to the first output shoulder tee, and the first detector, the first pulse shaper, the first trigger and the first integrator are connected in series with the output, while the second input of the first trigger is connected to the output of the trigger unit, from characterized by the fact that, in order to improve measurement accuracy, a second sensitive element is introduced, identical to the first sensitive element, whose input is connected to the second output tee arm, and the second detector, the second pulse shaper, the second trigger and the second integrator are sequentially connected to the output the first integrator is connected in series the first adder, the multiplier and the second adder, and the third adder is connected between the output of the second integrator and the second input of the second adder, while the output v cerned integrator coupled to the second input of the first adder, third adder output is connected to the second input of the multiplier, the second input of the second flip-flop connected to the output start block, the second input of the third adder is input to a reference voltage and the output of the second adder is the output of radio wave meter metal sheet thickness. 1183874 one 1183874 2