RU2545499C1 - Method for determining external volume of cylindrical item - Google Patents

Abstract

FIELD: measurement equipment.

SUBSTANCE: in a method for determining external volume of a cylindrical item, which applies interaction of electromagnetic waves with the test item, first, the item is placed in the first and the second electrical fields; the item is sounded with the first and the second orthogonally directed electromagnetic waves; the first and the second pairs of orthogonally polarised electromagnetic waves are received; correlation functions of constituents of the first and the second pairs of polarised waves are calculated, and item volume V is determined by the formula: $$V=\pi c^3{t}_{pd}^2\cdot t_{ph}/4n^3{\left(\Delta n-1\right)}^3,$$

where c - speed of propagation of an electromagnetic wave in free space; n - wave refraction parameter; Δn - difference of wave refraction parameters; t_pd - time of propagation of the polarised wave along the line of diameter of the cylindrical item (the first and the second pairs of polarised waves), t_ph - time of propagation of a polarised wave along the line of height of the cylindrical item (the first and the second pairs of polarised waves).

EFFECT: enlarging a measurement range.

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Description

The invention relates to the field of measuring equipment and can be used in process control systems.

A known method of measuring the geometric dimensions of various products, implemented by the device (see S. S. Savitsky "Methods and means of non-destructive testing", Minsk, 2012, pp. 180-182), containing as a sensitive element a short-circuited coil in which eddy currents. According to the principle of operation of this device, the controlled object is placed in the electromagnetic field of the coil, which is powered by alternating electric current. In this case, measuring the strength of eddy currents makes it possible to obtain information about the size of the geometric size of the product.

The disadvantage of this known method is the error associated with a change in the magnetic properties of the core of the coil and its winding due to temperature effects.

The closest technical solution to the proposed one is the method adopted by the author for determining the geometric size of the product, implemented by a device containing a measuring resonator in the form of a sensitive element (see S. S. Savitsky. "Methods and means of non-destructive testing", Minsk, 2012, pg. 57-59). According to this device, the resonator is first excited by electromagnetic waves and then a controlled article is placed in the resonator. By measuring the natural resonant frequency of the resonator, a change in the geometric size of the controlled medium is judged.

The disadvantage of this method is the limited measurement range due to the dependence of the volume of the measuring resonator on the geometric dimensions of the controlled medium.

The technical result of the proposed solution is to expand the measurement range.

The technical result is achieved by the fact that in the method for determining the external volume of a cylindrical product using the interaction of electromagnetic waves with a controlled product, the product is preliminarily placed in the first and second electric fields, the product is probed with the first and second orthogonally directed electromagnetic waves, the first and second pairs of orthogonally polarized electromagnetic waves are received waves, calculate the cross-correlation functions of the components of the received first and second pairs of polarized waves and volume products V m is determined by the formula:

, $$V=\pi c^3{t}_{pd}^2\cdot t_{ph}/\mathrm{four}{n}^3{\left(\Delta n-\mathrm{one}\right)}^3$$

,

where c is the speed of propagation of an electromagnetic wave in free space; n is the refractive index of the waves in the absence of applied electric fields; Δn is the difference in the refractive indices of the waves due to the anisotropy of the product; t _pd is the propagation time of the polarized wave along the line of the diameter of the cylindrical product (first and second pairs of polarized waves, t _ph is the propagation time of the polarized wave along the height line of the cylindrical product (first and second pairs of polarized waves).

The essence of the claimed invention, characterized by a combination of the above features, is that when probing an artificially polarized cylindrical product of the first and second orthogonally directed electromagnetic waves, the calculation of the correlation functions of the first and second pairs of orthogonally polarized waves makes it possible to determine the external volume of the cylindrical product.

The presence in the claimed method of a combination of the listed existing features allows us to solve the problem of determining the external volume of a cylindrical product based on the formation of artificial polarization and calculating the correlation functions of the first and second pairs of orthogonally polarized waves with the desired technical result, i.e. expanding the measuring range.

The drawing shows a functional diagram of a device that implements the proposed method.

A device that implements this technical solution contains a first electrode of a first electric field 1, a first radiation source 2, a first receiver 3, a second receiver 4 connected to a first input of a first correlator 5, a first electrode of a second electric field 6, a second radiation source 7, and a third receiver 8, the second electrode of the second electric field 9, the second correlator 10 connected by the second input to the fourth receiver 11, the second electrode of the first electric field 12 and the calculator 13. In the drawing, the number 13 indicates a cylindrical e product.

The essence of the proposed method is as follows. In nature, substances are known that have the property of anisotropy, and substances that do not have this property. This method involves measuring the external volume of a cylindrical product that does not have anisotropy.

From the theory of anisotropic substances it is known that when anisotropic matter is located (irradiated) by an electromagnetic wave, due to anisotropy, orthogonally polarized waves are formed in the substance, propagating through the material at different speeds. Due to the fact that this technical solution is aimed at measuring the volume of a non-anisotropic product, it is necessary to first place it in an electric field for acquiring a controlled product with anisotropy.

According to this method, the product is placed in the first and second electric fields, the lines of force of which are mutually perpendicular. After that, the artificially anisotropic controlled product is probed with the first and second electromagnetic waves, the lines of force of the electromagnetic fields of which are mutually perpendicular. As a result of all this, we obtain the first and second pair of orthogonally polarized waves propagating through the substance at different speeds due to the effect of double artificial polarization in the substance.

Let us designate the first pair of orthogonally polarized two waves, caused by the first electromagnetic field applied to the product and sensing the substance by the first electromagnetic wave, and the second by the second electric field applied to the product and sensing the product by the second electromagnetic wave.

In the case under consideration, if we assume that the lines of force of the first electromagnetic wave coincide (are parallel) with the lines of force of the first electric field and they are directed along the line of height of the cylindrical product, then in this case, due to anisotropy, one component of the first pair of anisotropic waves will propagate along the line the height of the cylindrical product, and the second along the diameter of the cylindrical product, i.e. we will have two orthogonally polarized waves. In this case, the component propagating parallel to the force lines of the first electric field will lag in the propagation velocity from the component propagating perpendicular to the force lines of the first electric field.

When applied to an already artificially anisotropic first electric field, a cylindrical product and a second electric field probed by the first electromagnetic wave and sensing this product with a second electromagnetic wave, taking into account the above conditions of orthogonality of the force lines, both electric fields and electromagnetic fields of the first and second waves can be indicate the existence of a second pair of orthogonally polarized waves (the lines of force of the second electric field are parallel to the lines of force of the second electric magnetic wave). In this case, a component of this pair, propagating parallel to the force lines of the second electric field (along the line of the diameter of the cylindrical product), will lag behind the propagation velocity from the component propagating perpendicular to the lines of force of the second electric field (along the height of the cylindrical product).

In this case, for the propagation times of the orthogonally polarized first and second pairs of electromagnetic waves, we can write:

t _1h = h / υ ₁ ; t _1d = d / υ ₂ ;

t _2h = h / υ ₂ ; t _2d = d / υ ₁ ,

where t _1h and t _1d are the propagation times of the first pair of orthogonally polarized waves; t _h2 and t _2d are the propagation times of the second pair of orthogonally polarized waves; h is the height of the cylindrical product; d is the diameter of the cylindrical product; υ ₁ is the propagation velocity of polarized waves propagating parallel to the lines of force of the first and second electric fields; υ ₂ is the propagation velocity of polarized waves propagating perpendicular to the lines of force of the first and second electric fields. Moreover, due to double anisotropy in the controlled cylindrical product, the speed υ _{2 is} ahead of the speed υ ₁ . Therefore, for speeds υ ₁ and υ ₂ we can write:

υ ₁ = c / n; υ ₂ = c / nΔn,

where c is the propagation velocity of electromagnetic waves in free space, n is the refractive index of the waves in the absence of laid electric fields, Δn is the difference in the refractive indices of the waves due to the anisotropy of the product (Δn = rn ³ E _vn / 2, where r is the linear electro-optical effect, E _vn is the intensity of the external electric field). Given the latest formulas, expressions (1) can be rewritten as t _1h = hn / c; t _1d = dnΔn / c; t _2h = hnΔn / c; t _2d = dn / c.

In the case under consideration, it is assumed that h> d. In addition, it is assumed that the characteristics of the first and second electric fields applied to the product and the products of the first and second electromagnetic waves probed by the product are the same.

The determination of the external volume of this cylindrical product according to the proposed technical solution is reduced to the determination of the height and diameter (radius) of the cylindrical product. To this end, the use of cross-correlation signal processing describing the dependence of the propagation times of the orthogonally polarized first and second pairs of electromagnetic waves on the diameter, height of the cylindrical product and refractive index (n) and the difference in refractive index (Δn) of electromagnetic waves is proposed.

To determine the height of the cylindrical product, signals are processed correlatively, having the form: t _1h = hn / c and t _2h = hnΔn / c. Here, since t _2h > t _1h , then, taking into account the theory of cross-correlation of two functions, in order to find the time lag between these signals, it is necessary to delay the leading signal in time, i.e. t _2h . Then the time lag determined by correlation processing should satisfy the condition:

t _ph = hn (Δn-1) / c,

where t _ph - time lag t _1h from t _2h , measured after correlation processing. As a result, solving the last formula with respect to h makes it possible to calculate the height as follows:

. $$h=t_{ph}\cdot c/n\left(\Delta n-\mathrm{one}\right)\left(\mathrm{one}\right)$$

.

Similarly, after the correlation processing of the signals corresponding to t _1d and t _2d , you can first measure the time lag between these signals t _pd , and then calculate the diameter of the cylindrical product as

. $$d=t_{pd}\cdot c/\left(\Delta n-\mathrm{one}\right)\left(2\right)$$

.

The joint solution of equations (1) and (2), taking into account the measurement features of cylindrical products, makes it possible to determine the external volume V of a cylindrical product by the formula:

. $$V=\pi c^3{t}_{pd}^2\cdot t_{ph}/\mathrm{four}{n}^3{\left(\Delta n-\mathrm{one}\right)}^3$$

.

In the proposed technical solution, the double artificial anisotropy of the cylindrical product 13 is organized by the first 1, second 12 electrodes of the first electric field and the first 6, second 9 electrodes of the second electric field. After that, the product is probed simultaneously by electromagnetic oscillations of the first radiation source 2 and the second radiation source 7. In this case, the edge of the product should be chosen as the place for introducing electromagnetic waves into the product so that the orthogonally polarized waves formed propagate along the height and diameter lines of the cylindrical product. Further, the components from the first pair of orthogonally polarized waves are received by the second 4 and fourth 11 receivers. Components of the second pair of orthogonally polarized waves are received by the third 8 and first 3 receivers. The output signal of the second receiver, which picks up the component from the first pair of polarized waves with the lines of force perpendicular to the power lines of the first probe wave, is fed to the first input of the first correlator 5. The output signal of the third receiver, which picks up the component from the second pair of polarized waves, is fed to the second input of the first correlator with lines of force parallel to the lines of force of the second electric field. The output signal of the first receiver, which picks up the component from the second pair of polarized waves with the lines of force perpendicular to the lines of force of the second probe wave, is fed to the first input of the second correlator 10. The output signal of the fourth receiver, which picks up the component from the first pair of polarized waves, is fed to the second input of the second correlator with lines of force parallel to the lines of force of the first probe wave. The output signals of the first and second correlators, respectively, are supplied to the first and second inputs of the calculator 13, which reflects information about the determination of the external volume of the cylindrical product.

Thus, based on cross-correlation treatments of two pairs of orthogonally polarized waves arising in a cylindrical product due to its double artificial anisotropy, it is possible to provide an extension of the measuring range of the geometric size of the controlled medium.

Claims (1)

A method for determining the external volume of a cylindrical product by using the interaction of electromagnetic waves with a controlled product, characterized in that the product is first placed in the first and second electric fields, the product is probed with the first and second orthogonally directed electromagnetic waves, the first and second pairs of orthogonally polarized electromagnetic waves are received, calculate the cross-correlation functions of the components of the received first and second pairs of polarized electromagnetic waves and eat V products are determined by the formula

,
where c is the speed of propagation of an electromagnetic wave in free space; n is the refractive index of the waves in the absence of applied electric fields; Δn is the difference in the refractive indices of the waves due to the anisotropy of the product; t _pd is the propagation time of the polarized wave along the line of the diameter of the cylindrical product, t _ph is the propagation time of the polarized wave along the line of height of the cylindrical product.