RU2790885C2 - Method for measurement of radius of curvature of long-length tube, and device for its implementation (options) - Google Patents

Abstract

FIELD: measuring equipment.

SUBSTANCE: group of inventions relates to measuring equipment for determination of radii of curvature of long-length tubes. A device for measurement of radius of curvature of a long-length pipe includes three sensors located at certain distances one after the other along a longitudinal axis of the tube under study. The device consists of a case, in which all three sensor are placed, among which the middle sensor is located in the middle part of the case at a random distance from one of edge sensors, and an additional sensor is installed opposite the middle sensor. Sensors are part of distance control units, each of which also includes thrust, at one end of which a roller is installed, a guide, and a spring, one support end of which rests on the other end of thrust, and the second one rests on the inner surface of the case or another part fixed from movements. An additional distance control unit is installed opposite the middle distance control unit. The device includes at least one length meter connected to the roller, or the middle roller, or an additional roller.

EFFECT: increase in the accuracy of measurements of radius of curvature of a long-length tube.

8 cl, 4 dwg

Description

The invention relates to measuring technology and can be used to determine the curvature of long pipes, including flexible tubing of coiled tubing units.

A device is known for measuring the radius of curvature of the cylindrical surface of large-sized parts, containing a housing, a support-based assembly, including a measuring and locating legs, and a reading device that interacts with the measured surface. The supporting elements of this device are fixed on two carriages, made with the possibility of smooth movement along the scale applied to the side surface of the housing, to change the base distance and fix them in the selected position, while the ends of the basing legs are made knife-shaped, and their contact surface is oriented in the direction perpendicular to the longitudinal axis of the hull (RF Patent No. 95096, IPC G01B 5/213 (2006.01). Published on June 10, 2010).

A device is known for measuring the radius of curvature of the cylindrical surface of large parts, containing a housing resting on the measured surface with support rollers fixed at its ends at a base distance from each other, a measuring transducer located in the middle of the base distance, while the housing is configured to change base distance, contains rectangular through holes with permanent magnets embedded and fixed with locking screws, located symmetrically with respect to the measuring transducer along the length of the body and designed to hold this device on the side and lower parts of the surface of the investigated cylindrical object during the measurement process (RF Patent No. 153456, IPC G01B 11/255 (2006.01) Published July 20, 2015 Bull. No. 20).

The above devices are mainly intended to control the radius of the circle of a cylindrical object in its cross section. Their use in determining the radius of curvature of the longitudinal axis of a long cylindrical product causes certain difficulties in the control process and increases the duration of the measurement, since real-time readings are not taken in the designs of these devices, which is their main drawback.

A known method for determining potentially dangerous pipeline sections with an off-design level of stress-strain state, which consists in the calculation of bending stresses performed according to in-line diagnostics, during which the measurement of the elastic bending radii of the pipeline is carried out using an in-pipe tool moving in its cavity (RF Patent No. 2602327 , IPC F16L 1/00 (2006.01) Published November 20, 2016, Bull. No. 32).

The assessment of bending stresses in the material of the pipeline being examined by this method is carried out using in-line diagnostics, the disadvantages of which include the long duration of preparatory work carried out before the control process, and the need for access of the measuring device to the internal cavity of the pipeline.

A known method for measuring the radius of curvature of the pipeline according to geodetic measurements, in which a reference line is formed in the horizontal and (or) vertical planes, measurements are made using a laser plane builder, and then using a tachometer and tape measure, geodetic measurement errors are minimized by performing a certain calculation procedure (Patent RF No. 2592733, G01B 11/00 (2006.01). Published on July 27, 2016, Bull. No. 21).

The disadvantages of this method include the long duration of the process of determining the curvature and the need for measurements of complex and expensive measuring instruments.

Closest to the claimed method is a method for determining the curvature of a rail under a loaded wheel, which consists in the fact that directly near the loaded wheel moving at a given speed, determine the relative movement of three points located on the working surface of the rail head, the coordinates of which determine the curvature, bending moment and stresses from bending of a given rail, while the measurement accuracy is ensured by choosing the measurement base and the value of the axial load (RF Patent No. 2108423, B61K 9/08 (1995.01), E01B 35/00 (1995.01)).

The disadvantage of this method is that the value of the examined radius of curvature depends on the loading scheme of the object under study, the wrong choice of which can lead to unreliable control results.

The invention is based on the task of developing a method for measuring the radius of curvature of a long pipe and a device for its implementation, which will provide measurement results that do not depend on the pipe loading scheme, and will allow measurements to be taken without using reference values of the geometric characteristics of the cross section of this pipe, which will lead to an increase measurement accuracy.

To solve the problem in the claimed method, which consists in the continuous determination of the relative displacement of three points, simultaneously with the determination of the relative displacement of the three points, the diameter of the investigated pipe is measured, while the measurement of the relative displacement of the three points and the diameter is carried out in at least one measurement plane passing through the longitudinal the axis of the test pipe, while the three points, the relative movement of which is to be measured, coincide with the centers of two rollers and the middle roller located between them, which are installed at certain distances one after the other along the longitudinal axis of the test pipe and are in constant contact with its outer surface in the control process, while the position of the centers of the rollers is determined by the readings of the sensors associated with them, and the position of the middle roller is determined by the readings of the middle sensor associated with it, while the pipe diameter is measured using the media installed opposite each other the bottom roller and the additional roller, the position of the center of which is determined using an additional sensor, then, based on the relative arrangement of three points coinciding with the centers of the two rollers and the middle roller placed between them, the radius of the circle described around the triangle, the vertices of which are located at these three points, is calculated, and determine the direction of the pipe bend in the base section, equal to the distance between the centers of the two extreme rollers, then depending on the direction of the pipe bend and taking into account its previously measured diameter, the radius of the circle circumscribed around the triangle, the vertices of which are located at three points coinciding with the centers of the two rollers and the middle roller placed between them, and the known radius of these rollers and the middle roller, determine the radius of curvature of the pipe axis, while in the case of its elastic bending, bending stresses are additionally calculated, while measurements are carried out as when moving all sensors, including the middle and complement sensors, along the longitudinal axis of the fixed pipe, and when the pipe moves longitudinally relative to the fixed sensors, including the middle and additional sensors.

To solve this problem, a device is claimed that includes three sensors located at certain distances one after another along the longitudinal axis of the pipe under study, while the device consists of a housing in which all three sensors are placed, among which the middle sensor is located in the middle part of the housing at an arbitrary distance from one of the extreme sensors, and an additional sensor installed opposite the middle sensor, while all sensors are part of the distance control units, each of which also includes a rod, at one end of which a roller is installed, a guide necessary to ensure free movement of the rod only in direction perpendicular to the longitudinal axis of the body, and a spring, one supporting end of which rests on the other end of the rod, and the second on the inner surface of the body or another part fixed from movement, while the middle sensor is part of the middle distance control unit, which also includes traction, on one horse on which the middle roller is installed, the guide necessary to ensure free movement of the rod only in the direction perpendicular to the longitudinal axis of the housing, and the spring, one supporting end of which rests on the other end of the rod, and the second on the inner surface of the housing or another part fixed from movement , while the additional sensor is part of an additional distance control unit installed opposite the middle distance control unit, while the additional distance control unit also includes a rod, at one end of which an additional roller is installed, a guide necessary to ensure free movement of the rod only in the direction perpendicular to the longitudinal axis of the body, and a spring, one supporting end of which rests on the other end of the rod, and the second - on the inner surface of the body or another part fixed from movement, while the device includes at least one length gauge connected to the roller, media it with a roller, or an additional roller.

In the first version of the device, sliding resistors are used as sensors, an average sensor and an additional sensor, the movable element of each of which is connected to the corresponding rod.

In the second version of the device, non-contact distance sensors are used as sensors, a middle sensor and an additional sensor, while the device is additionally equipped with a carriage necessary to reflect the signal of the distance sensor in the opposite direction.

An encoder or a pulse encoder is used as a length meter.

The claimed method using the claimed device performs an automated solution of a geometric problem, in which the axis of the investigated pipe in the base section, equal to the distance between the centers of the most remote rollers, the rolling of which during the control process occurs in one plane of measurement along one generatrix of this pipe, is a circle with a radius to be measured. Such a solution releases the values of controlled parameters from their dependence on the loading scheme. The use of an additional distance control unit together with a distance control unit located in the middle part of the device body makes it possible to scan the diameter of an elastic long pipe in the area of measuring its curvature, which makes it possible to determine bending stresses in the pipe material without taking into account the reference values of the geometric characteristics of the cross section of this pipe.

The technical result of the claimed invention is to increase the accuracy of measurements, achieved by minimizing the amount of initial data taken into account in the control process.

The minimization of the amount of initial data is carried out using the claimed method and device, which allow real-time determination of the curvature of a long pipe in at least one measurement plane by automated solution of a geometric problem in which the axis of the investigated pipe in the base section is equal to the distance between the centers of the most remote rollers, the rolling of which during the control process occurs in a given measurement plane along one generatrix of a given pipe, is a circle with a measured radius. Determining the diameter of a pipe in the plane of measurement of its curvature allows testing without taking into account the axial moment of inertia, the moment of resistance and other geometric characteristics of the cross section of this pipe.

In FIG. 1 shows a measuring device that uses sliding resistors to determine the parameters to be examined. In FIG. 2 shows a measuring device that uses distance sensors to determine the parameters to be examined. In FIG. 3 shows the position of the rollers on the convex section of the pipe surface. In FIG. 4 shows the position of the rollers on the concave section of the pipe surface.

In FIG. 1 adopted the following designations:

1 - body;

2 - distance control blocks;

2a - middle distance control block;

2b - additional distance control unit;

3 - pipe;

4 - roller;

4a - middle roller;

4b - additional roller;

5 - spring;

6 - thrust;

7 - guide;

8 - sensor (slider resistor);

8a - middle sensor (slider resistor);

8b - additional sensor (slider resistor).

In FIG. 2, the following designations are adopted:

1 - body;

2 - distance control unit;

2a - middle distance control unit;

2b - additional distance control unit;

3 - pipe;

4 - roller;

4a - middle roller;

4b - additional roller;

5 - spring;

6 - thrust;

7 - guide;

9 - distance sensor;

9a - middle distance sensor;

9b - additional distance sensor;

10 - carriage.

The device contains a housing 1 (Fig. 1 and 2), in which at least one measurement plane passing through the longitudinal axis of the investigated pipe 3 (Fig. 1 and 2), distance control blocks 2 are installed (Fig. 1 and 2), the middle distance control block 2a (Figs. 1 and 2) located between distance control blocks 2 (Figs. 1 and 2) at an arbitrary distance from one of them, and an additional distance control block 2b (Figs. 1 and 2) located opposite the middle distance control block 2a (Figs. 1 and 2) relative to the axis of the investigated pipe 3 (Figs. 1 and 2).

In one of the embodiments of the design of this device, each of the distance control blocks 2 (Fig. 1) consists of a rod 6 (Fig. 1), at one end of which a roller 4 (Fig. 1) is installed, a guide 7 (Fig. 1), necessary to ensure free movement of the thrust 6 (Fig. 1) only in the direction perpendicular to the longitudinal axis of the housing 1 (Fig. 1), the sensor - slide resistor 8 (Fig. 1). On the other end of the rod 6 (Fig. 1) rests one supporting end of the spring 5 (Fig. 1), which is also part of the distance control unit 2 (Fig. 1). The second support end of the spring 5 (Fig. 1) rests on the inner surface of the housing 1 (Fig. 1) or another part (not shown in Fig. 1), fixed from movement. The resistor slider 8 (Fig. 1), the body of which is fixed, is rigidly connected to the rod 6 (Fig. 1).

Middle distance control block 2a (Fig. 1), consisting of an average roller 4a (Fig. 1), rod 5 (Fig. 1), guide 6 (Fig. 1), spring 7 (Fig. 1) and an average sensor 8a ( Fig. 1) has the same design and dimensions as the distance control unit 2 (Fig. 1).

An additional distance control unit 2b (Fig. 1), consisting of an additional roller 4b (Fig. 1), a rod 5 (Fig. 1), a guide 6 (Fig. 1), a spring 7 (Fig. 1) and an additional sensor 8b ( Fig. 1) has the same design and dimensions as the distance control unit 2 (Fig. 1).

In another embodiment of the design of the measuring device, each of the distance control blocks 2 (Fig. 2) consists of a rod 6 (Fig. 2), at one end of which a carriage 10 (Fig. 2) is installed, having a roller 4 (Fig. 2), guide 7 (Fig. 2), necessary to ensure free movement of thrust 6 (Fig. 2) only in the direction perpendicular to the longitudinal axis of the body 1 (Fig. 2), fixed distance sensor 9 (Fig. 2). On the other end of the rod 6 (Fig. 2) rests one supporting end of the spring 5 (Fig. 2), which is also part of the distance control unit 2 (Fig. 2). The second support end of the spring 5 (Fig. 2) rests on the inner surface of the housing 1 (Fig. 2) or another part (not shown in Fig. 2), fixed from movement.

Middle distance control block 2a (Fig. 2), consisting of an average roller 4a (Fig. 2), rod 5 (Fig. 2), guide 6 (Fig. 2), spring 7 (Fig. 2), carriage 10 (Fig. 2), .2) and the middle distance sensor 9a (Fig. 2) has the same design and dimensions as the distance control unit 2 (Fig. 2).

Additional distance control block 2b (Fig. 2), consisting of an additional roller 4b (Fig. 2), thrust 5 (Fig. 2), guide 6 (Fig. 2), spring 7 (Fig. 2), carriage 10 (Fig. . 2) and an additional distance sensor 9b (Fig. 2) has the same design and dimensions as the distance control unit 2 (Fig. 2).

All rollers 4 (FIGS. 1 and 2), middle roller 4a (FIGS. 1 and 2) and additional roller 4b (FIGS. 1 and 2) are identical in radius.

The device also has at least one length gauge (not shown in Figs. 1 and 2) connected to one of the rollers 4 (Figs. 1 and 2), or the middle roller 4a (Figs. 1 and 2), or an additional roller 4b ( Fig. 1 and 2).

As a length gauge (not shown in Figs. 1 and 2), an encoder (not shown in Figs. 1 and 2) can be used, mounted on a rod 6 (Figs. 1 and 2) or on a carriage 10 (Fig. 2), the rotor of which is connected by a roller.

As an alternative to the encoder, a pulse sensor (not shown in Figs. 1 and 2) can be used, which is a magnetoelectric assembly.

The method is as follows.

The measurements are carried out during the longitudinal movement of the studied long pipe through a fixed measuring device or when the measuring device is moved along the axis of the fixed pipe.

In the process of measurement using distance control units 2 (Fig. 1 and 2) and the middle distance control unit 2a located between them (Fig. 1 and 2), which are installed in the housing 1 (Fig. 1 and 2) of the measuring device, continuously determine the mutual arrangement of the centers of the two extreme rollers 4 (Fig. 1 and 2) and the middle roller 4a (Fig. 1 and 2), each of which is in constant and tight contact with the outer surface of the pipe 3 (Fig. 1 and 2), provided with using a spring 5 (Fig. 1 and 2) through a rod 6 (Fig. 1 and 2), which can only move in the direction perpendicular to the longitudinal axis of the body 1 (Fig. 1 and 2) of the measuring device, which is ensured by the guide 7 ( Fig. 1 and 2). Continuous determination of the relative position of the centers of the rollers 4 (Fig. 1 and 2) and the middle roller 4a (Fig. 1 and 2) is carried out by recording signals from stationary sensors. As these sensors, slide resistors 8 (Fig. 1) and 8a (Fig. 1) or contactless distance sensors 9 (Fig. 2) and 9a (Fig. 2) can be used, which determine the positions of the centers of the rollers 4 (Fig. 2) and 4a (FIG. 2) by measuring the distances to the respective carriages 10 (FIG. 2).

Simultaneously with determining the relative position of the centers of the rollers 4 (Fig. 1 and 2) and the middle roller 4a (Fig. 1 and 2), the pipe diameter is measured using the middle distance control unit 2a (Fig. 1 and 2) and an additional distance control unit 2b ( Fig. 1 and 2).

Then, in each measurement plane, according to the relative position of the centers of the two rollers 4 (Fig. 3 and 4) and the middle roller 4a (Fig. 3 and 4), the radius of the circle described around the triangle is determined, the vertices of which coincide with the centers of the two rollers 4 (Fig. 3 and 4) and the middle roller 4a (Fig. 3 and 4), and the direction of bending of the pipe 3 (Fig. 3 and 4), which on the base section, equal to the distance between the centers of the rollers 4 (Fig. 3 and 4), can be determined as "convexity with respect to rollers", or "concavity with respect to rollers", or "lack of curvature".

In one of the calculation options, the radius R ₁ of a circle circumscribed around a triangle whose vertices coincide with the centers of the two extreme rollers 4 (Fig. 3 and 4) and the middle roller 4a (Fig. 3 and 4) can be calculated by the formula

where L ₁ - the distance between the centers of the extreme rollers 4 (Fig. 3 and 4);

δ ₁ - vertical displacement of the rightmost roller 4 (Fig. 3 and 4) relative to the middle roller 4a (Fig. 3 and 4), which is determined by the difference in the readings of the respective sensors;

δ ₂ - vertical displacement of the leftmost roller 4 (Fig. 3 and 4) relative to the middle roller 4a (Fig. 3 and 4), which is determined by the difference in the readings of the respective sensors;

L ₂ - the distance between the centers of the leftmost roller 4 (Fig. 3 and 4) and the middle roller 4a (Fig. 3 and 4).

In this case, the sine function in the denominator of the above expression is enclosed under the modulus sign in order to obtain only positive values of the calculation results.

In one of the calculation options, the direction of pipe bending 3 (Fig. 3 and 4) in the base section, equal to the distance between the centers of the extreme rollers 4 (Fig. 3 and 4) can be determined by the angle < ABC (Fig. 3 and 4), calculated by the formula

In this case, if < ABC is greater than π, which corresponds to Fig. 3, then pipe 3 (FIG. 3) will be identified as convex with respect to rollers 4 (FIG. 3) if < ABC is less than π, which corresponds to FIG. 4, then the shape of the bend of pipe 3 (fig. 4) will be recognized as concave with respect to rollers 4 (fig. 4), if < ABC is equal to π, then the shape of the pipe will be recognized as straight, i.e. having no curvature in the base section.

Further along the known radius of the circle described around the triangle, the vertices of which coincide with the centers of the rollers 4 (Fig. 3 and 4) and the middle roller 4a (Fig. 1 and 2), the known diameter of the investigated pipe 3 (Fig. 3 and 4), known the direction of its bending and the known radii of the rollers 4 (Fig. 3 and 4) and the middle roller 4a (Fig. 1 and 2) calculate the radius of curvature of the axis of the pipe 3 (Fig. 3 and 4), coinciding with the so-called neutral plane.

Meanwhile, according to FIG. 3, the radius of curvature of the axis "convex with respect to the rollers" pipe 3 (Fig. 3) is

R \u003d R ₁ - 0.5 d - r ,

where d is the diameter of the pipe, determined using the middle roller and the additional roller installed opposite each other, the positions of the centers of which are determined according to the readings of the middle sensor and the additional sensor, respectively;

r is the value of the radius of each of the rollers 4 (Fig. 3 and 4).

Meanwhile, according to FIG. 4, the radius of curvature of the axis "concave with respect to the rollers" pipe 3 (Fig. 4) is

R \u003d R ₁ + 0.5 d + r .

The radius of curvature of the pipe, which does not have a bend in the base section, equal to the distance between the centers of the two rollers 4 (Fig. 3 and 4), is equal to infinity.

Further, the parameters determined in more than one measurement plane are combined to obtain the total radius of curvature of the pipe.

In the case of elastic bending, bending stresses are additionally determined by the formula

where E is the modulus of elasticity of the material of the studied long pipe.

The distribution along the length of the pipe of the measured values of all the examined parameters, namely the radii of curvature, diameters and bending stresses in its material, is determined using a length meter (shown in Fig. 1 and 2), which can be used as an encoder (in Fig. 1 and 2 is not shown) or a pulse sensor (not shown in figs. 1 and 2), which generates pulses during the control process when the roller pressed against the surface of the pipe rotates so that when it passes over the surface of this pipe for a certain section of the path, one pulse occurs.

Example.

In several sections along the pipe, which is in a state of elastic bending, it is necessary to measure its radii of curvature and bending stresses arising in its material using the proposed method. The outer diameter of the investigated pipe is 38 mm, and the wall thickness is 3 mm. The pipe is made of steel 20 (longitudinal modulus E = 206 GPa)

The 38×3 pipe, in a state of elastic bending, is passed through a fixed measuring device, the design of which corresponds to the scheme in Fig. 1. An encoder (not shown in Fig. 1) is used as a length meter (not shown in Fig. 1).

The radius of each of the rollers 4 (Fig. 3 and 4) and the middle roller 4a (Fig. 3 and 4) is r = 10 mm. Dimensions L ₁ (FIGS. 3 and 4) and L ₂ (FIGS. 3 and 4) are 200 mm and 100 mm, respectively. The values of δ ₁ (Fig. 3 and 4) and δ ₂ (Fig. 3 and 4) are determined as the longitudinal movement of the investigated pipe through a fixed device according to the readings of slide resistors 8 (Fig. 1) and 8a (Fig. 1)

The radius of curvature and bending stresses in its material are determined automatically using a personal computer used to process the measurement results, according to the following dependencies.

To calculate the radius R ₁ (Fig. 3 and 4) the formula is used

The direction of the pipe bend is determined by the angle < ABC (Fig. 3 and 4), calculated by the formula

The radius of curvature of the axis R (Fig. 3 and 4) of the pipe is calculated depending on the direction of its bending by the formula

R \u003d R ₁ ± (0.5 d + r ).

The sign "-" is placed in the case when the pipe is convex in relation to the rollers 4 (Fig. 3) and 4a (Fig. 3), i.e. at < ABC > π, and the “+” sign is placed in the case when the pipe is concave with respect to rollers 4 (Fig. 4) and 4a (Fig. 4), i.e. for < ABC < π.

The diameter d of the pipe is determined using the middle roller 4a (Fig. 1) and the additional roller 4b (Fig. 1) installed opposite each other, the positions of the centers of which are determined according to the readings of the middle sensor 8a (Fig. 1) and the additional sensor 8b (Fig. 1).

Bending stresses are calculated by the formula

The table shows the results of calculating the radii of curvature of a 38×3 pipe and bending stresses in the zone of its maximum deflection and at distances of 1.5 m and 3 m from the zone of maximum deflection.

EFFECT: invention makes it possible to measure the radius of curvature of a long pipe and bending stresses in its material without taking into account the coefficients that determine the scheme of its loading, and the reference values of the geometric characteristics of the cross section of the pipe under study.

Table
The results of calculating the radii of curvature of a 38×3 pipe and bending stresses in the zone of its maximum deflection and at distances of 1.5 m and 3 m from the zone of maximum deflection Measurement area Diameter d, mm Vertical displacement δ ₁ , mm Vertical displacement δ ₂ , mm Angle ABC, rad. Radius R ₁ , m Radius of curvature of the pipe axis R, m Flexural stresses σ _bend , MPa Zone of maximum deflection (δ _max ) of the pipe 37.7 0.20 0.20 3.138 25,000 25.024 155.2 1.5 m from δ _max 37.7 6.00 -5.63 3.138 27.164 27.188 142.8 3 m from δ _max 37.9 10.64 -10.38 3.139 39.101 39.125 99.8

Claims (20)

1. A method for measuring the radius of curvature of a long pipe, which consists in continuously determining the relative displacement of three points, characterized in that, simultaneously with determining the relative displacement of the three points, the diameter of the investigated pipe is measured, while the measurement of the relative displacement of the three points and the diameter is carried out in at least one plane measurement passing through the longitudinal axis of the test pipe, while the three points, the relative movement of which is to be measured, coincide with the centers of two rollers and the middle roller located between them, which are installed at certain distances one after another along the longitudinal axis of the test pipe and are in constant contact with its outer surface in the control process, while the position of the centers of the rollers is determined by the readings of the sensors associated with them, and the position of the middle roller is determined by the readings of the middle sensor associated with it, while the pipe diameter is measured using the installed x opposite each other of the middle roller and the additional roller, the position of the center of which is determined using an additional sensor, then, by the relative arrangement of three points coinciding with the centers of the two rollers and the middle roller located between them, calculate the radius of the circle described around the triangle, the vertices of which are located on these three points, and determine the direction of the pipe bend in the base section, equal to the distance between the centers of the two extreme rollers, then depending on the direction of the pipe bend and taking into account its previously measured diameter, the radius of the circle described around the triangle, the vertices of which are located at three points, coinciding with the centers of the two rollers and the middle roller placed between them, and from the known radius of these rollers and the middle roller, the radius of curvature of the pipe axis is determined, while in the case of its elastic bending, bending stresses are additionally calculated, while measurements are carried out as when moving all sensors, including after the middle and additional sensors, along the longitudinal axis of the fixed pipe, and during the longitudinal movement of the pipe relative to the fixed sensors, including the middle and additional sensors. 2. A method for measuring the radius of curvature of a long pipe according to claim 1, characterized in that the radius of curvature of the pipe axis is calculated by the formula

where L ₁ - the distance between the centers of the two extreme rollers; δ ₁ - vertical displacement of the rightmost roller relative to the middle roller, which is determined by the difference in the readings of the respective sensors; δ ₂ - vertical displacement of the leftmost roller relative to the middle roller, which is determined by the difference in the readings of the respective sensors; L ₂ - distance between the centers of the leftmost roller and the middle roller; d is the diameter of the pipe, determined using the middle roller and the additional roller installed opposite each other, the positions of the centers of which are determined according to the readings of the middle sensor and the additional sensor, respectively, r - the value of the radius of each of the rollers, at the same time, after the first term, presented in this expression as a fraction, the sign "-" is indicated if the pipe is convex with respect to the rollers, and the sign "+" is indicated if the pipe is concave with respect to the rollers . 3. A method for measuring the radius of curvature of a long pipe according to claim 1, characterized in that in the case of elastic bending, the bending stresses are calculated by the formula

where E is the modulus of elasticity of the material of the studied long pipe; d is the diameter of the pipe, determined using the middle roller and the additional roller installed opposite each other, the positions of the centers of which are determined according to the readings of the middle sensor and the additional sensor, respectively; R is the radius of curvature of the pipe axis. 4. A device for measuring the radius of curvature of a long pipe, including three sensors located at certain distances one after another along the longitudinal axis of the investigated pipe, characterized in that the device consists of a housing in which all three sensors are placed, among which the middle sensor is located in the middle parts of the body at an arbitrary distance from one of the extreme sensors, and an additional sensor installed opposite the middle sensor, while the sensors are part of the distance control blocks, each of which also includes a rod, at one end of which a roller is installed, a guide necessary to ensure free movement of the rod only in the direction perpendicular to the longitudinal axis of the housing, and a spring, one supporting end of which rests on the other end of the rod, and the second on the inner surface of the housing or another part fixed from movement, while the middle sensor is part of the middle distance control unit , which includes the also a rod, at one end of which a middle roller is installed, a guide necessary to ensure free movement of the rod only in the direction perpendicular to the longitudinal axis of the housing, and a spring, one supporting end of which rests on the other end of the rod, and the second on the inner surface of the housing or another a part fixed from movement, while the additional sensor is part of an additional distance control unit installed opposite the middle distance control unit, while the additional distance control unit also includes a rod, at one end of which an additional roller is installed, a guide necessary to ensure free movement thrust only in the direction perpendicular to the longitudinal axis of the housing, and a spring, one supporting end of which rests on the other end of the rod, and the second - on the inner surface of the housing or other part fixed from movement, while the device includes at least one length gauge, connecting combined with a roller, or a middle roller, or an additional roller. 5. A device for measuring the radius of curvature of a long pipe according to claim 4, characterized in that sliding resistors are used as sensors, an average sensor and an additional sensor, the movable element of each of which is connected to a corresponding rod. 6. A device for measuring the diameter and radius of curvature of a long pipe according to claim 4, characterized in that non-contact distance sensors are used as sensors, the middle sensor and the additional sensor, while the device is additionally equipped with a carriage. 7. A device for measuring the radius of curvature of a long pipe according to claim 4, characterized in that an encoder is used as a length meter. 8. A device for measuring the radius of curvature of a long pipe according to claim 4, characterized in that a pulse sensor is used as a length meter.

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