RU2720437C1 - Method for automated control of articles continuity and device for its implementation - Google Patents

Abstract

FIELD: measuring equipment.

SUBSTANCE: invention relates to measurement equipment and can be used for evaluation of reliability and quality of various items. Method comprises placing on a product at the beginning of a scanning path a reference defect corresponding to the actual defect in the article according to characteristics and having dimensions corresponding to the minimum possible size of the defect in the article, measurement before control of the signal value on the article at a distance of not more than the size of the minimum defect, measuring the value of the signal change on the reference defect, setting the value of the threshold signal for detecting defects in the article, two-dimensional scanning in coordinates x, y of surface of the monitored object along the trajectory of reciprocal motion with a physical field radiation sensor with pitch Δx, Δy, exposing the article during scanning to a physical field in form of a pulse signal with frequency f_p, measurement of value of radiation signals of physical field after interaction with article from each point of article surface, registration of defects by comparison of current value of signal along scanning path with value of threshold signal. According to the invention, when a defect is detected, the pulse frequency of the exposure is increased by the physical field and the scanning pitch is reduced. After jumping beyond boundaries of j-th defect, pulse frequency and scanning pitch are reduced. Method is implemented using a device for automated control of articles continuity.

EFFECT: provision of efficient reliable control of continuity of multilayer complex structures and their elements in production process and in real operating conditions, id est reduced error of determining boundaries and location of defect areas without reducing control efficiency.

3 cl, 18 dwg, 2 tbl

Description

Technical field

The invention relates to the field of measuring equipment and can be used to assess the reliability and quality of various products. The use of this product for the control of materials with a large variation in characteristics (this variation is determined by the variation in the characteristics of various physical fields after their impact on the controlled material — thermal, acoustic, radio waves) is especially relevant, for example, multilayer structures made of polymer composite materials (PCM).

The invention can be used to control the reliability and quality of complex spatial multilayer PCM structures both during production and during operation: pipelines, spatial mesh structures, spacecraft compartments, rocket engines, aircraft engine elements, and sealed vessels.

Particularly effective is the application of the claimed invention when testing potentially dangerous and expensive structures to manufacture, on which, on the one hand, high demands are placed on reliability and quality of operation, on the other hand, they are quite expensive and time-consuming to manufacture, so that a large number of structures can be replaced other products having the required parameters. Reliable defect identification is very important for products operating in potentially hazardous conditions - oil and gas pipelines, rocket and space technology products, where there are mutually exclusive requirements: on the one hand, it is necessary to ensure the necessary reliability of the structure (for example, increase its thickness), and on the other hand, there are restrictions on weight and overall dimensions, which require reducing the thickness of the materials. An important role in this is played by economic aspects. In this case, it is necessary to identify potentially dangerous places (structural units), which in the first place can be destroyed (due to the presence of defects such as discontinuity), which can lead to an accident and which may need to be strengthened.

State of the art

A reliable determination of the quality of material continuity is an urgent task in the process of creating effective and reliable structures from various materials.

There are a large number of methods for controlling the continuity of the material: x-ray, ultrasound, visual optical, eddy current, as well as their combinations.

All methods have their own characteristics and applications. But all methods have one common operation - the process of detecting discontinuities (defects), i.e. the allocation in the controlled material of areas having characteristics different from the main material. It can be, for example, cracks, delaminations, etc.

At the same time, the requirements for detection methods are required to detect defects with the necessary reliability, defining the boundaries of defects with the necessary error.

The problem of detecting and identifying defects is significantly complicated by the complex shape of the surface of the products (for example, a cylindrical shape) and complex internal structure, large overall dimensions of the products, and a random variation in the characteristics of the products on their surface (which is especially typical for PCM).

A promising direction in modern technology is the use of composite materials, both metallic and polymeric, which have a number of advantages over traditional materials, especially in the oil and gas industry, aerospace industries, engineering, and energy. This is due to the wide variety of types of such materials, the specific features of their structures and manufacturing technology, and a number of advantages over metals.

In addition, these materials in most industries operate under static and dynamic loads.

Improving the quality of structures is impossible without a reliable assessment of the quality criteria of materials. Accordingly, it is impossible to develop measures and technologies to improve the quality of structures. Signs of the quality of structures, especially in pipelines, rocket and space and aviation industries, are the mass and size and energy characteristics, which are determined, including quality of material continuity.

Of great importance are methods of non-destructive testing based on various physical principles, and methods reliable for the problem of detecting internal discontinuities by analyzing changes in the results of the interaction of physical fields with controlled material. They allow you to objectively determine the actual state of the structure, evaluate the reliability of their operation and give recommendations for its repair or restoration.

Methods for detecting defects and identifying defects such as disruption during automated non-destructive testing are described in detail in: EP 0486689 A1, SU 1396046 A1, SU 1158919 A, SU 319895, SU 1649414 A1, SU 824032, DE 4031895 A1, SU 2171469, SU 2676857, SU 145435, SU 2650711, SU 2654298, SU 2666158, SU 172618.

A common drawback of almost all existing methods and means of automated non-destructive testing is the large error in determining the boundaries of defective areas when determining the threshold value of a signal from a reference defect and detecting defective areas by comparing the signal over the surface of the material being monitored with the threshold value of the signal. This is due to the fact that when setting up a control system for a reference defect, in order to ensure maximum control performance (especially with automated control of large structures), the maximum possible scanning step is selected for scanning (usually three times less than the size of the minimum reference defect) and the minimum frequency probing pulses for maximum performance without loss of reliability of defect detection.

Closest in technical essence to the presented method and device are the method and device described in the work of I.N. Ermolov, N.P. Aleshin, A.I. FLOWS. Unbrakable control. Acoustic control methods. Prince 2. - M .: Higher school, 1991, p. 92-95.

The known method includes the following steps:

- placement of a reference defect on the controlled product that corresponds to the characteristics of real defects in the product and having a minimum size Δx _e × Δy _e at the beginning of the scanning path, where Δx _e is the length of the reference defect in the direction of the scanning path, and Δy _e is the length of the reference defect in the direction perpendicular scan paths

- measurement before monitoring the magnitude of the signal on the monitored product near the reference defect - U _{i = 0} , where i is the integer coordinate of the controlled surface along the scanning path,

- measuring the magnitude of the change in the signal at the reference defect - ΔU _e = U _e -U _{i = 0} , where U _e is the value of the signal at the reference defect,

- setting the threshold signal to detect defects in the product as follows:

U _then = U _{i = 0} + ΔU _e xn,

where 0 <n <1 - the coefficient is determined experimentally or as a result of the calculation before the control,

- two-dimensional scanning (at x, y coordinates) of the surface of the controlled object along the path of the reciprocating or spiral movement of information sensors of the physical field with a step Δу,

- introduction to the product during the scanning of the physical field in the form of a signal with a pulse frequency f _and ,

- measuring the magnitude of the signals (U _i ) the radiation of the physical field after interacting with the controlled object from each point on the surface of the controlled object,

- registration of anomalous zones (defects) M _j , comparing the current value of the signal along the scan path with the threshold value of the signal, for example:

here j is the serial number of the defect along the scan path,

it is assumed here that the signal at the anomalous zone (defect) will be greater than the threshold value of the signal,

However, this method has significant drawbacks inherent in all of the above technical solutions: ensuring maximum performance increases the error in determining the boundaries of detected defects. This worsens the metrological characteristics of the system and control technology, reduces the likelihood of determining a defective attribute of the product, etc.

Subject to the conditions for ensuring a small error in the boundaries of the defects, the known method has low productivity.

Due to the random location of defects in the product, the current scanning path of the information signal sensor for the product may change randomly with respect to the located defect, which increases the likelihood of an increase in the error in determining the coordinates of the boundaries of defects, its area, size, etc. This reduces the reliability of the control.

The same book describes the closest to the proposed device for automated non-destructive quality control of an object, including series-connected

- a unit for measuring the magnitude of the radiation signal of the physical field, including radiation sensors and registration of the physical field and the pulse generator of the signal,

- threshold device

- registrar.

This device does not allow to determine the coordinates of the boundaries of the defects with a small error while ensuring high performance.

Therefore, today there is a need to create a method for monitoring real structures from complex materials, which can be applied in practice for a wide range of objects with different characteristics and can detect various types of internal defects with a minimum error in the coordinates of their location, sizes, etc. with a fairly high performance.

The technical result, the achievement of which the present invention is directed, is to provide real-time reliable quality control of the continuity of multilayer complex structures and their elements in the production process and in real operating conditions, i.e. reducing the error in determining the boundaries and location of defective areas without reducing the performance of the control.

Those. ultimately, the invention solves the problem of increasing the safety of operation of complex potentially hazardous structures.

SUMMARY OF THE INVENTION

This technical result in terms of the method is achieved due to the fact that in the method of automated control of product continuity, including: placing on the product at the beginning of the scanning path of a reference defect corresponding in characteristics to the real defect in the product and having dimensions Δx _e × Δy _e corresponding to the minimum possible size of the defect in the product, where Δh _e - length of the reference defect in the scanning direction of the trajectory, Δu _e - reference defect length in the direction perpendicular trae Torii scan - the measurement before the control signal value on the product at a distance of not more than the minimum size of the defect - U _{i = 0,} where i - the integer coordinates inspection surface along the trajectory scanning, measuring the amount of change of the signal on the reference defect - ΔU _e = U _e - U _{i = 0} , where U _e is the value of the signal at the reference defect, setting the threshold signal to detect defects in the product as follows:

U _then = U _{i = 0} + ΔU _e xn,

where n is the coefficient selected before the control from the range - 0 <n <1,

two-dimensional scanning in x-coordinates, at the surface of the controlled object along the path of reciprocating motion by the radiation sensor of the physical field with a step Δх, Δу, the impact on the product during scanning by the physical field in the form of a pulse signal with a frequency f _and , measurement of the magnitude of the signals (U _i ) radiation of the physical field after interacting with the product from each point on the surface of the product, registration of defects M _j , by comparing the current value of the signal along the scanning path with the value of the threshold signal :

here j is the serial number of the defect along the scan path,

provided that the signal from the defect is greater than the threshold signal value,

when the j-th defect M _j = 1 is detected, the frequency f _{and the} pulses of exposure to the physical field are increased by Δf _and : f _p = f _and + Δf _and ,

where Δf _and is the change in the frequency of the signal, f _p is the operating frequency of the pulses during registration of the signal, which is set when a defect is detected,

and reduce the scanning step Δy by (δΔy):

Δy _p = Δy-δΔy, where Δy _p - the working step of the scan, which is set when determining the defect,

- after going beyond the boundaries of the j-th defect at M _j = 0, the frequency f _{p of the} pulses is reduced to f _and ,

- and the scanning step Δy _{p is} reduced to a value of Δy.

The technical result is also achieved due to the fact that as a physical field using ultrasonic, radio wave, x-ray or infrared.

The technical result is also ensured by the use of a device for automated control of the continuity of products, including a unit for measuring the magnitude of the radiation signal of a physical field, including radiation sensors of a physical field and a pulse generator, a scanning system, a threshold device and a recorder, while the scanning system is installed with the possibility of providing relative movement of the product and a signal measuring unit for scanning the surface of the product along the paths of the recipient or spiral motion, and the output of the signal pulse generator is connected to the input of the physical field sensor, into which are entered: positioning unit, comparison unit, adder, multiplier, scanning system control unit, signal pulse generator control unit and memory unit, while the radiation signal of the physical field, including the sensors of the radiation of the physical field and the pulse generator of the signal, is configured to affect the defective product by the physical field, the output of the scanning system we are connected to the input of the positioning unit, the first output of the positioning unit is connected to the third input of the recorder, the second output of the positioning unit is connected to the second input of the comparison unit, the output of the measurement unit of the radiation signal of the physical field is connected to the first input of the comparison unit, the first output of the comparison unit is connected to the first the input of the threshold device, the second output of the comparison unit is connected to the first input of the adder, the third output of the comparison unit is connected to the input of the memory unit, the fourth output of the cp block avoniya is connected to the first input of the multiplier, the output of the memory block is connected to the second input of the multiplier, the output of the multiplier is connected to the second input of the adder, the output of the adder is connected to the second input of the threshold device, the first output of the threshold device is connected to the second input of the control unit of the signal pulse generator, the second output of the threshold the device is connected to the first input of the control unit of the signal pulse generator, the third output of the threshold device is connected to the first input of the control unit of the scanning system the fourth output of the threshold device is connected to the second input of the control unit of the scanning system, the fifth output of the threshold device is connected to the first input of the recorder, the sixth output of the threshold device is connected to the second input of the recorder, the output of the control unit of the signal pulse generator is connected to the input of the signal pulse generator, the output of the block control system of the scanning system is connected to the input of the scanning system.

Brief Description of the Drawings

The invention and the possibility of achieving a technical result will be more clear from the following description with reference to the position of the drawings, where:

FIG. 1 shows a typical dependence of the error in determining the boundaries of the defect (identification of the minimum defect) on the performance of the control,

FIG. 2 presents a diagram of the formation of an error in determining the boundaries of a defect,

FIG. 3 shows a functional diagram of the device,

FIG. 4 shows a photograph of the installation and hardware (unit for measuring the radiation signal of a physical field and a control panel) of an automated control device,

FIG. 5 shows a photograph of the location of the reference defect on the surface of the controlled product.

FIG. 6 is a photograph of a block of acoustic piezoelectric transducers.

FIG. 7 is a photograph of a control unit of a scanning device.

FIG. 8 is a diagram of a positioning unit.

FIG. 9 shows the location of artificial defects on the surface of the product, two defectograms with detected defects according to the known method (defectogram "a") and the claimed method (defectogram "b"),

FIG. 10 shows examples of a scanning path along the surface of a controlled product: a reciprocating path and a spiral path,

FIG. 11 is a photograph of a positioning unit,

FIG. 12 shows a scanning system,

FIG. 13 shows a diagram of a simulator of a defect (reference defect),

FIG. Figure 14 shows the dependence of the relative errors in determining the areas of defects during scanning over the surface of the test object at various inspection steps for single defects with the calculation of errors by the formula (1),

FIG. Figure 15 shows the dependence of the relative errors in determining the areas of defects when scanning over the surface of the test object at various inspection steps for single defects with the calculation of errors by the formula (2),

FIG. 16 shows the location of simulators of defects on the product,

FIG. 17 shows the results of automated control (spiral pitch 14 mm),

FIG. Figure 18 shows the dependence of the relative error in calculating the area on the size of the defect.

The following notation is used in the figures:

1 - controlled product

2 - internal defect in the product,

3 - scanning system,

4 - unit for measuring the magnitude of the radiation signal of a physical field,

5 - sensors of radiation of a physical field,

6 - signal pulse generator,

7 - threshold device

8 - the registrar.

9 - positioning unit,

10 is a block comparison

11 - adder

12 - multiplier,

13 - control unit of the scanning system,

14 - control unit of the signal pulse generator,

15 is a block of memory.

16 - paths of reciprocating and spiral scanning.

17, 18 - ultrasonic proximity transducers,

19, 20 - sliding rods to establish the optimal distance between the ultrasonic transducers and the controlled product,

21 - photodiode,

22 - an opaque flag or disc with slots,

23 is a rectangular signal from the positioning unit,

24 - control panel.

i is the integer coordinate of the controlled surface along the scanning path,

U _{i = 0} , U ₀ - the value of the signal near the reference defect,

U _e is the magnitude of the signal at the reference defect,

ΔU _e - the magnitude of the signal change at the reference defect,

U _pop - threshold value of the signal,

Δx _e - the length of the reference defect in the direction of the scan path,

Δу _e - the length of the reference defect in the direction perpendicular to the scanning path,

U _i - the current value of the signal at a point with the coordinate "i" along the scan path,

Δy is the scanning step along the "y" axis perpendicular to the "x" axis is the scanning path,

Δх is the scanning step in the direction of the scanning path,

X is the coordinate along the scan path,

S is the area of the defect,

ΔS / S × 100% - the error in determining the area of defects,

P is the performance control

Preferred Embodiment

All used electronic components of a device that implements the presented method are built on the basis of standard electronic elements, using logic circuits, microprocessor circuits and microprocessor assemblies with reprogrammable memory devices (see, for example, Ugryumov E.P. Digital circuitry: textbook for universities. - 3rd ed. Revised and revised - St. Petersburg: - BHV-Petersburg, 2010.).

As a unit for measuring the signal of a physical field, a pulse generator, etc. the modernized ultrasonic low-frequency flaw detector of the USD-60 brand (Fig. 5) with BP-4 non-contact transducers (www.kropus.ru) was used. Sensors that record fields other than ultrasound can be used, as described above.

The method is as follows.

A functional diagram of the device is shown in FIG. 3.

In the controlled product 1, a reference defect 2 is established, corresponding in terms of characteristics to real defects in the product and having the minimum dimensions Δx _e x Δy _e at the beginning of the scan path (Fig. 10), where Δy _e is the length of the reference defect in the direction of the scan path, Δx _e - the length of the reference defect in the direction perpendicular to the scan path.

The reference defect must correspond to the real defect in its basic informational features. For example, to dimensions: thickness (opening) of 0.2 mm, and dimensions of 30 × 30 mm. However, a real defect is not necessarily a defect such as discontinuity, for example, the presence of an air cavity in the material. A real defect can be very different: a local internal violation of the dielectric constant, a change in density, etc. The minimum dimensions of the reference defect must correspond to the minimum possible size of the defect that may be contained in the product. Those. initially examine the product for the presence of defects in it, their types and sizes, establish the dimensions of the minimum defect and then form a reference defect with these minimum sizes.

In FIG. Figure 5 shows a photograph with a reference defect 2 installed on the surface of the product 1 in the form of a special net packaged in a film simulating the acoustic delamination of the internal delamination in a multilayer composite material.

Block 3 (Fig. 4) carries out the mutual movement of the monitored product 1 and the unit for measuring the magnitude of the signal of the physical field 4. Types of physical fields: ultrasonic (ultrasonic control), radio wave (radio wave control), X-ray (X-ray control), infrared (infrared or thermal control ) etc.

Thus, scanning (inspection) of the surface of the controlled product is carried out along a reciprocating or spiral path. In FIG. 10 shows the reciprocating and spiral trajectories. The purpose of these trajectories is to fill 100% of the surface of the controlled object with the sensor area, i.e. without gaps view the entire surface. The reciprocating trajectory is used to control flat products. When monitoring products such as bodies of revolution, a spiral path is used. In general, a spiral trajectory is a special case of a reciprocating trajectory, because in both trajectories, each subsequent scan line is separated from the previous one by a certain step.

During the scanning process, a signal about the location of the scanning point from the scanning system 3 enters the positioning unit 9 (Fig. 8, Fig. 11).

Before the control by the signal field measuring unit of the physical field 4, the signal value is measured by the signal measuring unit (Fig. 4) on the product 1 near the reference defect 2-U _{i = 0} , where i is the integer coordinate of the surface to be monitored along the scanning path. For this, the generator 6 excites the radiation sensor 5 of the physical field with a signal of frequency f _and . The sensor 5 (Fig. 6) introduces radiation into the product 1, registers the magnitude of the radiation signal after interacting with the product 1, and in block 4, this signal is measured. Close - means "at a distance of no more than the size of the minimum defect."

Then, in the same way, before the control is carried out, the magnitude of the signal change at the reference defect ΔU _{e is} measured.

In FIG. 4, 12 are photographs of shadow ultrasonic monitoring devices by which measurements were made. Here 17, 18 are ultrasonic non-contact transducers, 19. 20 are sliding rods to establish the optimal distance between the ultrasonic transducers 19, 20 and the controlled product 1.

The signals U _{i = 0} and ΔU _e from block 4 by the enable signal (i = 0) from block 4 through block 10 enter the adder 11 and the multiplier 12, respectively.

Block 10 in this case plays the role of a switch: at the initial moment of scanning at i = 0 (i is the integer coordinate of the scanning path) passes the signal U _{i = 0} to the adder 11.

At the same time, from the block of comparison 10 in the block of memory 15 receives the enable signal at i = 0. The memory block 15 stores the previously entered coefficient "n", which can vary from 0 to 1 and determines the probability characteristics of defect detection.

According to these signals, the value of "n" from the memory block 15 enters the multiplier 12, where the value is determined ΔU _e x n. The coefficient "n" determines the probability of detecting a defect.

If n = 1, then U _then = U _{i = 0} + ΔU _e and the defect will be skipped, because the threshold signal is greater than the change in signal at the reference defect.

If n = 0, then U _pop = U _{i = 0} , then all anomalies not related to the defect will be detected as defects, i.e. false detection of defects will occur.

This coefficient is selected in several ways:

and. Measured noise characteristics of the information signal σ _W and n

1-σ _W / ΔU _e , b.

Often this coefficient is set based on the need to identify all defects, in which case it will be close to zero; or from the condition that there is no rejection, in this case it will be close to 1.

There are other methods for determining this coefficient. This operation is carried out at the stage of testing control methods.

This value from the multiplier 12 enters the adder 11, where the threshold signal value is formed:

U _pop = U _{i = 0} + ΔU _e xn

The threshold value of the signal from the adder 11 enters the threshold device 7, where defects are detected

here j is the serial number of the defect along the scan path,

it is assumed here that the signal at the anomalous zone (defect) will be greater than the threshold value of the signal,

In the process of monitoring, the scanning device relocates the controlled product 1 and the signal measuring unit 4 along a predetermined path, for example (Fig. 10).

In the scanning process for i> 0, the signal U _i from block 4 through block 10 enters the threshold device 7, where defects are detected.

If a defect M _j = 1, the signal supplied to the first input of the pulse generator 14 signals the control unit 6. By this signal generator 6 reconstructs the excitation frequency by an amount Δf _u and begins to excite oscillations at a frequency f _p = f + Δf _{and u.}

f _p - the operating frequency of the pulses during registration of the information signal, the frequency that is set when a defect is detected.

At the same time, from the third output of the threshold device 7, a control signal is supplied to the first input of the control unit of the scanning device 13. According to this signal, when the j-th defect M _j = 1 is detected, the scanning device 3 reduces the step of the reciprocating or spiral scanning Δу by the amount (δΔу):

Δy _p = Δy-δΔy.

After the detection of the defect along the scanning path — after the sensor 5 reaches the boundary of the jth defect and the transition to a high-quality section of the product being monitored (M _j = 0) from the threshold device, the corresponding initiative signals arrive at blocks 13 and 14, according to which the frequency f _{p of the} introduction pulses in the product of the physical field in the form of a signal decreases to a value of f _{and the} step of a reciprocating or spiral scan Δy _p decreases to a value of Δy.

At the same time, signals about the presence or absence of defects from the threshold device 7 are received in the recorder 8. At the same time, a signal about the location of the defects is received from the positioning unit 9 in the recorder 8.

The registrar 8 is the registration of the final information and the formation of the final documents.

With a predetermined extent of the defect perpendicular to the scanning direction, Δy is much larger than the scanning step Δy _p (Δy >> Δy _p ), when a defect is detected, the value of Δy _p does not change.

In the case of pre-known length of the defect in the direction of scanning Δh much greater than the scan pitch _p Δh (Δh >> Δh _p), upon detection of the defect _{and the} value of f is not changed,

here Δx _p = V × f _and , where

V is the speed of the information sensor in the direction of the scan path.

The control process is controlled from the control panel 24.

The purpose of the positioning unit 9 (Fig. 8, Fig. 11) is to register the coordinates of the point on the surface of the product 1 at which the signal is measured.

The positioning unit 9 operates as follows.

The signal from the scanning system 3 enters the positioning unit 9, which fixes the location of the signal registration point by the unit 4 on the surface of the product 1.

Registration is carried out in the form of pulses - integer coordinates.

A diagram of the positioning unit is shown in FIG. 8. It works as follows.

A check mark (slotted disc) 22 is rigidly connected to the controlled product 1.

During scanning by the device 3, the flag 22 at the end of the scanning period (for example, at the end of the revolution of the cylindrical product 1) periodically interacts with the photodiode 22. As a result, a rectangular signal 23 is generated at the output of the photodiode 22 with a period corresponding to the circumference of the monitored product or the scanning step Δу.

Thus, automated control of the claimed method and device is carried out.

The following is a theoretical assessment of the error in determining the area of defects by the presented method of automated control of product continuity and a device for its implementation

According to OST 3-5145-90, the error in determining the boundaries of defects is equal to half the diameter (length, width) of the installation base of the converter. This error will be minimal if the scanning step does not exceed the diameter of the transducer. From the point of view of the analysis of defects errors, 2 options are possible: the error in determining the area of a single defect and the total error in determining the area of several defects. Consider these issues in more detail.

Suppose we have a simulator of a defect or an artificial discontinuity embedded in a sample in the form of a conditional square with side a, where

Δx is the scanning step along the circumference, Δy is the scanning step along the generatrix (Fig. 13). For the convenience of calculation, we assume that the scanning steps along the circumference and the generatrix are the same.

Then the area of one detected defect is S = a × a. We take the criterion Δx = Δy - the scan step is equal to the error in determining the boundary of the defect. Then the maximum addition to the area on one side of the square is ΔS _i = a × Δx.

Therefore, the maximum total error area ΔS = 4 × ΔS _i = 4 × a × Δх. Suppose that the location of the defect boundary between two scan samples is equally probable, which is equivalent to a 2-fold decrease in the scan step.

With this in mind, we obtain the following formula for calculating the error in determining the area of a defect in the presence of a scanning system:

In FIG. Figure 14 shows the dependence of the relative errors in determining the areas of defects during scanning over the surface of the test object at various inspection steps for single defects with the calculation of errors by formula (1). The relative error in determining the area δSrel was calculated by the formula:

A more accurate version of calculating the area of a single defect is possible. Let the area of one detected defect S = a × a. The criterion Δx is defined in the same manner as in the preceding embodiment. Then the area of one defect S _δ , taking into account the error, is written in the following form:

Hence, the maximum error in determining the area of one defect, taking into account the error in determining its boundary, is written as:

Usually, at small values of Δx, the square of its value Δx ^{2 is} negligible and equal to zero Δx ² = 0. Then ΔS = 2 × а × Δх, and formulas (1) and (2) coincide. However, with Δx≥1 and the size of the defects not exceeding Δx by more than an order of magnitude, the contribution of Δx ² may have a weight. Then the final expression for ΔS will be the expression (3).

In FIG. Figure 15 shows the dependence of the relative errors in determining the areas of defects during scanning over the surface of the test object at various inspection steps for single defects with the calculation of errors by formula (2). The relative error in determining the area δSrel was determined by the formula:

Comparing the calculation results, we can say that the difference in the errors in determining the areas of defects can be 2 times different depending on the size of the defect and the scanning step.

Findings:

1) The calculation according to formula (1) is applicable only for a rough estimate of the error in calculating the area, while the calculation according to formula (3) is mathematically more accurate.

2) To estimate the error in the results of automated control, we use the formula (4), which will reduce the error in determining the areas of defects during automated control.

Experimental studies of the method for automated control of the continuity of products and devices for its implementation were aimed at assessing the possibility of detecting defects of a given size and determining the error in calculating their area on the cylindrical surface of the product.

It was established experimentally that if the product has an internal delamination with an opening of at least 0.2 mm and a minimum size of 30 × 30 mm, when conducting non-destructive testing using the ultrasonic transmission method, the signal level drop at the defect is about 8-10 dB.

To confirm the characteristics of an automated system in terms of determining defects of a minimum size, defect simulators are used.

For research, several simulators of defects of a square shape in the following sizes were prepared:

- 20 × 20 mm (4 cm ² );

- 30 × 30 mm (9 cm ² );

- 50 × 50 mm (25 cm ² );

- 70 × 70 mm (49 cm ² ).

On a cylindrical PCM product, artificial defects such as discontinuity with various parameters were laid over the entire surface.

The simulator, when placed on the outer or inner surface of the product when conducting non-contact ultrasonic testing using the transmission method, provides a drop in the level of transmitted radiation by 6-8 dB, which corresponds, as studies have shown, to the presence of a defect of the type delamination in the structure of the material of the product.

Defect simulators were placed on the outer surface of the product according to the circuit shown in FIG. 16. Thus, an imitation of defects such as delaminations in the structure of a pipe made of a polymer composite material was carried out.

The product was installed on a mechanized scanning system (Fig. 12).

By the method, the ultrasonic equipment and scanning parameters of the automated system were tuned. The appearance of the system is shown in FIG. 12, in FIG. 4 - operator workstation.

By setting FIG. 12, a spiral scan of the surface of the product was carried out. In accordance with the claimed method and device, a threshold signal value was determined. Further, during the scanning process, a signal was measured from each point over the entire surface area of the product.

The resolution of the measurement was determined by the positioning unit 4, Fig 8. and Fig. 11 (coordinate sensors).

Further, this product was subjected to non-destructive testing according to two methods:

- by a known method (method) adopted as a prototype,

- according to the invention.

The signal during control by both methods was measured by the same signal measuring unit 4.

The results are shown in the defectograms shown in FIG. 9.

When conducting a series of five experiments on non-destructive testing of a product with simulators of defects of various sizes, the results of calculating the areas of detected defects were obtained, which are shown in Table 1.

The analysis showed that the proposed automated control method and device for its implementation provide for the detection of defects with a size of at least 30 × 30 mm with a satisfactory error for production.

Based on the data given in table 1, the experimental dependence of the relative error in calculating the area of the defect on its size is obtained (Fig. 17). The obtained characteristic confirmed the previously conducted theoretical studies.

The analysis of defectograms and the results of processing to determine the error in determining the boundaries and coordinates of the location of defects clearly shows that the method according to the invention allows to detect all artificial defects embedded in the product with an error of less, approximately, 30%.

As an example, table 2 shows the results of processing experimental studies.

Experimental studies confirm the achievement of the technical result: the method according to the invention reduces the error in determining the sizes and coordinates of the detected defects, increases the efficiency and reliability of the quality control of the continuity of multilayer complex structures and their elements, and therefore increases the safety of operation of complex potentially dangerous structures.

Claims (54)

1. The method of automated control of the continuity of products, including: - placement on the product at the beginning of the scanning path of the reference defect corresponding to the characteristics of the real defect in the product and having dimensions Δx _e × Δu _e corresponding to the minimum possible defect sizes in the product, where Δx _e is the length of the reference defect in the direction of the scanning path, Δy _e - the length of the reference defect in the direction perpendicular to the scanning path, - measurement before monitoring the magnitude of the signal on the product at a distance of not more than the size of the minimum defect - U _{i = 0} , where i is the integer coordinate of the surface to be monitored along the scanning path, - measuring the magnitude of the change in the signal at the reference defect - ΔU _e = U _e -U _{i = 0} , where U _e is the value of the signal at the reference defect, - setting the threshold signal to detect defects in the product as follows: U _pop = U _{i = 0} + ΔU _e xn, where n is the coefficient selected before the control from the range - 0 <n <1, - two-dimensional scanning in x coordinates, at the surface of the controlled object along the path of the reciprocating motion of the radiation sensor of the physical field with a step Δх, Δу, - the impact on the product during scanning by the physical field in the form of a pulse signal with a frequency f _and , - measuring the magnitude of the signals (U _i ) the radiation of the physical field after interacting with the product from each point on the surface of the product, - registration of defects M _j , by comparing the current value of the signal along the scanning path with the value of the threshold signal:

here j is the serial number of the defect along the scan path, provided that the signal from the defect is greater than the threshold signal, characterized in that - upon detection of the j-th defect M _j = 1 increase the frequency f _{and the} pulses of exposure to the physical field by Δf _and : f _p = f _and + Δf _and , where Δf _and is the change in the frequency of the signal, f _p is the operating frequency of the pulses during registration of the signal, which is set when a defect is detected, and reduce the scanning step Δy by (δΔy): Δy _p = Δy-δΔy, where Δy _p - the working step of the scan, which is set when determining the defect, - after going beyond the boundaries of the j-th defect at M _j = 0, the frequency f _{p of the} pulses is reduced to f _and , - and the scanning step Δy _{p is} reduced to a value of Δy. 2. The method according to p. 1, characterized in that as a physical field using ultrasonic, radio wave, x-ray or infrared. 3. Device for automated control of the integrity of products, including - a unit for measuring the magnitude of the radiation signal of a physical field (4), including sensors for radiation of a physical field (5) and a pulse generator of a signal (6), - scanning system (3), - threshold device (7) and - registrar (8), the scanning system is installed with the possibility of providing relative movement of the product and the signal measuring unit for scanning the surface of the product along the paths of reciprocating or spiral motion, and the output of the signal pulse generator (6) is connected to the input of the physical field sensor (5), characterized in that introduced into it: - positioning unit (9), - comparison block (10), - adder (11), - multiplier (12), - control unit of the scanning system (13), - a control unit for the signal pulse generator (14) and - memory block (15), wherein the unit for measuring the magnitude of the radiation signal of the physical field (4), including the sensors of the radiation of the physical field (5) and the pulse generator of the signal (6), is configured to affect the product (1) with the defect (2), - the output of the scanning system (3) is connected to the input of the positioning unit (9), - the first output of the positioning unit (9) is connected to the third input of the recorder (8), - the second output of the positioning unit (9) is connected to the second input of the comparison unit (10), - the output of the unit for measuring the magnitude of the radiation signal of the physical field (4) is connected to the first input of the comparison unit (10), - the first output of the comparison unit (10) is connected to the first input of the threshold device (7), - the second output of the comparison unit (10) is connected to the first input of the adder (11), - the third output of the comparison unit (10) is connected to the input of the memory unit (15), - the fourth output of the comparison unit (10) is connected to the first input of the multiplier (12), - the output of the memory unit (15) is connected to the second input of the multiplier (12), - the output of the multiplier (12) is connected to the second input of the adder (11), - the output of the adder (11) is connected to the second input of the threshold device (7), - the first output of the threshold device (7) is connected to the second input of the control unit of the signal pulse generator (14), - the second output of the threshold device (7) is connected to the first input of the control unit of the signal pulse generator (14), - the third output of the threshold device (7) is connected to the first input of the control unit of the scanning system (13), - the fourth output of the threshold device (7) is connected to the second input of the control unit of the scanning system (13), - the fifth output of the threshold device (7) is connected to the first input of the recorder (8), - the sixth output of the threshold device (7) is connected to the second input of the recorder (8), - the output of the control unit of the signal pulse generator (14) is connected to the input of the signal pulse generator (6), - the output of the control unit (13) by the scanning system is connected to the input of the scanning system (3).

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