RU2619356C1 - Device for measuring wire diameter - Google Patents

Abstract

FIELD: measuring equipment.

SUBSTANCE: proposed device for measuring the wire diameter comprising a metal tube and a cavity resonator on the measuring section, comprising a segment of this metal tube, a controlled wire is located coaxially within the metal tube, an electronic unit for excitating electromagnetic waves in the cavity resonator and measuring the resonant frequency of electromagnetic waves, electrically connected to the cavity resonator via the communication line and the communication element. Herewith the metal tube is made of the three sections, the first and the second sections of which have the same inner diameter outside the measuring section, and the third section, located between them on the measuring section and forming a coaxial cavity resonator with the wire of the fluctuation type H_m1p (M=1, 2, 3, …; p=1, 2, 3, …), has an inner diameter enlarged in comparison with the inner diameter of the metal tube at its first and the second sections. The frequency of the electromagnetic oscillations excited in the coaxial cavity resonator, open at both ends, is chosen less than the critical excitation frequency of electromagnetic waves in the coaxial waveguides formed by the wire and each of the first and the second sections of the metal tube outside the measuring section.

EFFECT: improving the measurement accuracy.

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Description

The invention relates to measuring equipment and can be used for non-contact measurement of the diameter of the wire as a finished product, and in its production. It can also be used to measure the diameter of other extended metal products (rods, threads, etc.).

Known reflectometry method for measuring the diameter of extended metal products and the device that implements it (monograph: Viktorov V.A., Lunkin B.V., Sovlukov A.S. High-frequency method for measuring non-electric quantities. M .: Nauka. 1978. 280 p. S. 248-249). These technical solutions provide a sufficiently high accuracy of diameter measurement within its measurement 0 ÷ 4 mm. At higher values of the diameter change, the error in its determination increases significantly. The disadvantage of this method and device is the limited scope due to the small measurement range.

A device is also known for measuring the diameter of a wire using an open microwave resonator in the form of a combination of two metal reflecting mirrors coaxial with the axis of rotation (SU 873155, 10/15/1981). The controlled wire crosses the axis of the resonator at a right angle. The measurement of the diameter of the wire is based on the measurement of the angle of rotation of the resonator, providing a fixed value of the losses introduced into the resonator by a controlled wire (shift of resonant frequencies). The rotation angle meter associated with the cavity rotation mechanism and calibrated in diameter values determines the average diameter value. The disadvantages of this device are limited functionality due to the complexity of its implementation and the unreliability of the structure caused by the presence of movable structural elements.

A technical solution is also known (monograph: Viktorov V.A., Lunkin B.V., Sovlukov A.S. Radio wave measurements of technological process parameters. M.: Energoatomizdat. 1989. 208 p. 61-62), which contains a description devices, the technical nature of which is closest to the proposed device and adopted as a prototype. This prototype device contains a cylindrical volume resonator in the form of a cavity of a metal pipe and end metal planes. A controlled wire located along the axis of this resonator passes through small through holes in the metal end planes of the cavity. Electromagnetic oscillations of type E ₀₁₀ or type E _{110 are} excited in this volume resonator. By measuring the resonant frequency of electromagnetic waves of a given resonator, determine the diameter of the wire. The disadvantage of this device is its limited functionality, allowing you to control wires with small diameters; otherwise, it is necessary to make large through holes in the end planes of the resonators, which leads to an unacceptable decrease in the quality factor of the resonators due to the loss of electromagnetic energy due to the emission of electromagnetic waves through these holes.

The technical result of the invention is the expansion of functionality.

The technical result in the proposed device for measuring the diameter of the wire containing a metal pipe and a volumetric resonator on the measuring section, including a segment of this metal pipe, a controlled wire, an electronic unit for excitation of electromagnetic oscillations in the volume resonator and measuring the resonant frequency of electromagnetic oscillations, electrically connected through a communication line and a communication element with a volume resonator, is achieved by the fact that the metal The pipe is made of three sections, the first and second sections of which outside the measuring section have the same inner diameter, and the third section, located between them on the measuring section and forming a coaxial volume resonator with oscillations of the type H _m1p (m = 1, 2, 3 ...; p = 1, 2, 3, ...), has an inner diameter increased compared to the inner diameter of the metal pipe in its first and second sections, while the frequency of electromagnetic waves excited in a coaxial volume resonator open from both ends, selected less than the critical frequency of excitation of electromagnetic waves in coaxial waveguides formed outside the measuring section by the wire and each of the first and second sections of the metal pipe.

The proposed device for measuring the diameter of the wire is illustrated by the drawing in FIG. one.

Here, a cavity resonator 1, a transverse waveguide 2, a wire 3, a metal pipe 4, a communication line 5, a communication element 6, an electronic unit 7 are shown.

The device operates as follows.

On the measuring section - where it is necessary to measure the diameter of the wire being monitored - they form an oscillating system - a cavity resonator with a piece of metal pipe coaxial with respect to the wire outside the wire. Excitation of electromagnetic waves — standing electromagnetic waves — within the measuring section is possible if conditions are created at its boundaries under which these boundaries will reflect electromagnetic waves incident on them from the cavity bounded by the wire and the pipe inner surface in the given measuring section. To create such boundary conditions, it is proposed to organize an out-of-band propagation mode for the electromagnetic waves excited in the measuring section on both sides of the wire’s measuring section. In this case, this measuring section becomes a volume resonator, electromagnetic waves in which exist in accordance with the excited type of oscillations.

To physically ensure the existence of electromagnetic waves within the measuring section and the non-proliferation mode (i.e., the transcendental mode) outside of it can be done by positioning the outside of the wire coaxially with respect to it a piece of metal pipe, with a difference in the diameters of which within the measuring section and outside it is possible transcendental mode outside this section. In this case, the wire and metal pipe form a coaxial line. If oscillations are excited in a measuring section — a coaxial-type volume resonator in a certain range often [f ₁ , f ₂ ], corresponding to a change in the wire diameter in the measured range, then it is necessary that the geometric parameters of the transverse waveguides at these frequencies be such that the critical frequency f _cr their excitation was higher than the maximum frequency f _{2 the} range of variation of the resonator frequency. Then the radiation of electromagnetic waves outside the measuring section of the wire will be absent, and high-quality oscillations will exist in the cavity of this volume resonator.

Design features of the device. The highest type of wave in the coaxial line, characterized by the largest critical wavelength λ _cr , is H ₁₁ , starting with wavelengths λ> λ _krH11 ≈π (R ₁ + R ₂ ), where R ₁ and R ₂ are the radii of the inner and external line conductors. Then follows the type of field E ₀₁ , starting with λ> λ _крЕ01 ≈π (R ₂ -R ₁ ), etc. The natural (resonant) frequency f _{p of} such a resonator is close to the natural frequency of a closed coaxial resonator and can be estimated by the formula (monograph: Milovanov OS, Sobenin NP Technique of superhigh frequencies. M .: Atomizdat. 464 p. S. 45-46):

where l is the cavity length; p = 0, 1, 2, ...; c is the speed of light.

Formula (1) when working on vibrations of the type H ₁₁₁ takes the form

Oscillations of type H _m1p (m = 1, 2, 3 ...; p = 1, 2, 3, ...), among which the lowest type is H ₁₁₁ with an eigenfrequency defined by formula (2). In this case, we have the following expression for the critical wavelength λ _krH11 (monograph: Milovanov OS, Sobenin NP Technique of superhigh frequencies. M: Atomizdat. 464 p. S.45-46):

and, accordingly, formula (3), the following expression for f _cr :

where R is the value of the inner radius R _{2 of the} metal pipe outside the measuring section with a volume resonator.

A feature of the waves of these H-types, characterized by an arbitrary first index m, but the second index 1, is the presence in the formula for λ _{cr of the} sum of the radii R ₁ and R ₂ . It is this that determines, as is not difficult to see, an increase in the inner diameter 2R _{2 of the} metal pipe within the volume resonator compared to its diameter, that is, the diameter of the transcendental waveguides located on both sides of this volume resonator.

In fact, the condition f ₂ <f _cr can be written taking into account (1) and (3) in the following form:

or after conversions

Here R is the radius of the outer conductor of the coaxial line at the transverse end sections of the resonator, that is, the value of the inner radius R _{2 of the} metal pipe outside the measuring section with a volume resonator. Since the second term (fraction) of the product on the right-hand side of this inequality is less than unity, then it holds if R <R ₂ .

The device of FIG. 1 contains a resonator sensor in the form of a coaxial volume resonator 1 of a coaxial type with end sections — transverse waveguides 2, a controlled wire 3, a metal pipe 4, a communication line 5, a communication element 6, an electronic unit 7.

In the resonator sensor, which is an open cavity volume resonator 1 in the form of a segment of a coaxial line with segments of coaxial transcendental waveguides 2 conjugated at both ends thereof, electromagnetic waves are excited. To form this coaxial volume resonator, a metal pipe 4 is arranged coaxially with the outside of the controlled wire 3. Excitation and removal of oscillations in the resonator, as well as measurement of the natural (resonant) oscillation frequency, which changes when the diameter of the controlled wire is changed, and its conversion into the output signal are carried out through communication line 5 and communication element 6 (metal pin, communication loop) connected to the volume resonator 1, using the electronic unit 7. The number of communication elements (one or two) op edelyaetsya applied measurement circuit; This figure shows the excitation of vibrations in the resonator and their removal with a single metal pin. The metal pipe 4 can be made relatively thin by increasing its inner diameter only in the area where the volume resonator is organized.

The synthesis of a device implemented using a metal pipe located coaxially with the outside of the wire and having an increased inner diameter on the measuring section consists of the following sequence of actions: choose, based on the technological features of a particular task, for example, permissible accuracy and weight, the value of the radius R ₂ metal pipes, and also, proceeding, in particular, from the necessary degree of locality of measurements, the length l of this part of the pipe; then, on the basis of formulas (1) or (2), the range of variation of the resonance frequency f _{p is} calculated and, knowing its maximum value f ₂ , the radius R of the metal pipe outside the resonator is determined (and, therefore, the value of the jump R-R2 of the radius of this pipe in the boundary sections resonator) in such a way as to satisfy the condition f ₂ <f _cr , where f _cr is the critical frequency of a coaxial waveguide with an outer conductor of radius R; f _cr = s / λ _cr , s is the speed of light; the better the frequencies f ₂ , f _cr satisfy this inequality, the shorter the wave of transcendental waveguides that electromagnetic energy weakens (is reflected) exponentially (usually this value is several centimeters, which is quite acceptable).

Note that the proposed device is operable on just one of the highest types of vibrations in the coaxial resonator under consideration, since the vibrations in it on the main TEM type are characterized by a very low Q factor (end “jumps” of radii are small for observing resonant pulses, which also have no functional depending on the radius R ₁ ).

Thus, this device allows you to make non-contact measurements of the diameter of the wire and other extended metal products (rods, threads, etc.) both in one and, if necessary, simultaneously in several of their sections.

Claims (1)

A device for measuring the diameter of a wire containing a metal pipe and a volume resonator on the measuring section, including a segment of this metal pipe, a controlled wire placed coaxially with the inside of the metal pipe, an electronic unit for excitation of electromagnetic waves in the cavity and measuring the resonant frequency of electromagnetic waves, electrically connected by means of a communication line and a communication element with a volume resonator, characterized in that the metal pipe is made of three parts Cove, the first and second portions which is measuring section have the same inner diameter, and a third portion located between the measuring section and forming a conductor coaxial cavity resonator with the oscillations of type H _m1p (m = 1, 2, 3 ...; p = 1 , 2, 3, ...), has an inner diameter increased in comparison with the inner diameter of the metal pipe in its first and second sections, while the frequency of electromagnetic waves excited in a coaxial volume resonator open from both ends is less than critical what is the frequency of excitation of electromagnetic waves in coaxial waveguides formed outside the measuring section by the wire and each of the first and second sections of the metal pipe.

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