CN104990984B - A kind of device and method for improving magnetic striction wave guide detection sensitivity - Google Patents

Abstract

The invention discloses a device for improving the detection sensitivity of a magnetostrictive guided wave, and a method for improving the detection sensitivity of a magnetostrictive guided wave by using the device. A central processor controls a signal generator to generate an excitation signal, which is input to an excitation sensor through a power amplifier. In the area to be detected, the ultrasonic guided wave is excited and propagated along the axial direction; after the reflection of the signal enhancement element, the ultrasonic guided wave is superimposed and enhanced, and then input to the receiving sensor, and input to the A/D converter through the signal preprocessor, and converted into a digital signal input Central processor: The central processor obtains the position of the defect on the area to be detected by analyzing the digital signal. The present invention introduces a signal enhancement element into the traditional magnetostrictive guided wave detection device to realize the amplitude enhancement of multiple echo signals of defects and achieve the purpose of improving the detection sensitivity of the guided wave. The defect detection without blind spots can be realized through transformation.

Description

A device and method for improving detection sensitivity of magnetostrictive guided waves

technical field

The invention belongs to the field of non-destructive testing, and more specifically relates to a device and method for improving the detection sensitivity of magnetostrictive guided waves.

Background technique

In petroleum, chemical, energy and other industries, pipes and pipelines are widely used, and after long-term use, failure forms such as corrosion, perforation or wall thickness reduction will occur. In order to avoid accidents, regular non-destructive testing of industrial pipelines is required. Ultrasonic guided wave detection technology has the advantage of realizing rapid detection of a section of area with single-point excitation, and is widely used in this field.

The invention patent with application number 96193606.1 discloses a non-destructive inspection method for pipes and pipes using magnetostrictive sensors (the date of publication is May 27, 1998), and mainly introduces a method for inspecting ferromagnetic pipes or other cylindrical shells. Structural methods and apparatus in which the magnetostrictive effect is utilized to detect defects within structures. However, in actual detection, due to the complex working conditions, the ultrasonic guided wave attenuates greatly during the propagation process, which reduces the detection sensitivity. The invention patent with application number 200810013047.6 discloses a method and device for ultrasonic guided wave composite non-destructive testing (disclosure date is March 10, 2010), which uses electromagnetic and piezoelectric methods to realize the excitation and reception of ultrasonic guided waves. Under the condition of pipeline attenuation, the purpose of defect detection with longer distance and higher sensitivity is achieved.

However, the existing technology only optimizes the guided wave detection technology from the excitation or reception mode, and realizes defect detection based on the primary echo signal of the defect. At this time, the attenuation will not only reduce the sensitivity of defect detection, but also reduce When the value is not obvious or the defect is in the detection blind zone, it is easy to miss the defect detection.

Contents of the invention

Aiming at the above defects or improvement needs of the prior art, the present invention provides a device and method for improving the detection sensitivity of magnetostrictive guided waves. The amplitude of the secondary echo can be increased to improve the detection sensitivity, and at the same time, the problem of missed detection of defects due to detection blind spots can be eliminated during the detection process.

In order to achieve the above object, according to one aspect of the present invention, a device for improving the detection sensitivity of the magnetostrictive guided wave is provided, which is characterized in that it includes a signal enhancement element, which is used to reflect the ultrasonic guided wave signal on the one hand, so that the ultrasonic guided wave The signal is enhanced after superposition, and on the other hand, it is used to absorb the ultrasonic guided wave propagating from the outside of the detection area to the inside, reducing the influence of interference signals on the detection.

Preferably, the device also includes an excitation sensor, a receiving sensor, a signal generator, a power amplifier, a signal preprocessor, an A/D converter and a central processor;

The signal generator is used to generate an excitation signal, the excitation signal is input to the excitation sensor through the power amplifier, and is excited on the detection object to generate an ultrasonic guided wave signal;

The receiving sensor is used to receive the ultrasonic guided wave signal and convert it into a detection signal, and the detection signal is transmitted to the A/D converter through the signal preprocessor and converted into a digital signal;

The central processor is used to control the signal generator to generate an excitation signal, and receive the digital signal in the A/D converter for analysis and processing;

The signal enhancement element is used to reflect the ultrasonic guided wave signal in the detection area, so that the ultrasonic guided wave signal received by the receiving sensor is superimposed and strengthened, and at the same time, it is used to absorb the ultrasonic guided wave that propagates from the outside of the detection area to reduce the reception The influence of the interference signal received by the sensor on the detection.

According to another aspect of the present invention, there is also provided a method for improving the detection sensitivity of the magnetostrictive guided wave by using the above-mentioned device, which is characterized in that, on the one hand, the signal enhancement element is used to reflect the ultrasonic guided wave signal, so that after the superimposed ultrasonic guided wave signal On the other hand, it absorbs the ultrasonic guided wave propagating from the outside of the detection area to the inside, reducing the influence of interference signals on the detection.

Preferably, the method comprises the steps of:

(1) The central processor controls the signal generator to generate an excitation signal, which is input to the excitation sensor through a power amplifier, and is excited on the detection object to generate an ultrasonic guided wave, and propagates along the axial direction of the detection object;

(2) When the ultrasonic guided wave encounters a defect in the detection area, an echo signal is generated, and the echo signal is reflected by the signal enhancement element and superimposed at the receiving sensor to enhance the amplitude;

(3) The echo signal after the amplitude enhancement is converted into a detection signal by the receiving converter, and then input into the A/D converter through the signal preprocessor, and converted into a digital signal;

(4) After the central processor receives the digital signal, it processes and analyzes to obtain the location of the defect.

Preferably, before step (1), two signal enhancing elements are arranged at both ends of the area to be detected, the excitation sensor and the receiving sensor are arranged between the two signal enhancing elements, and the signal generator passes through the power amplifier and the excitation sensor The receiving sensor is connected with the A/D converter through the signal preprocessor, and the central processor is respectively connected with the input end of the signal generator and the output end of the A/D converter.

Preferably, the excitation sensor is located adjacent to one of the signal enhancing elements.

According to another aspect of the present invention, there is also provided a signal enhancement element, which is characterized in that it includes an inner layer and an outer shell;

The inner layer includes a reflection module, and the outer shell fixes the inner layer on the outer surface of the detection object in a radial direction, so that the reflection module exerts pressure on the detection object, causing the detection object to produce reversible deformation, and is used to reflect the ultrasonic wave that passes through this part. Wave.

Preferably, the detection object is rod-shaped or tubular, and the inner diameters of the attenuation module and the reflection module are 0.1 mm to 2.0 mm smaller than the outer diameter of the detection object.

Preferably, the inner layer further includes an attenuation module arranged in parallel with the reflection module in the axial direction, for absorbing the ultrasonic guided wave propagating inward from the outside of the detection area.

As a further preference, the shape of the inner surface of the inner layer is the same as that of the outer surface of the detection object, so as to ensure that the reflection module and the attenuation module can be closely attached to the detection object when fixed.

As a further preference, the material of the reflection module is steel, aluminum or copper, and the material of the attenuation module is rubber, nylon or polytetrafluoroethylene.

As a further preference, the inner layer further includes partitions, which are respectively located at both ends of the inner layer, and between the attenuation module and the reflection module, for fixing the attenuation module and the reflection module in the axial direction; The thickness of the partition is smaller than the thickness of the attenuation module and the reflection module, so as to ensure that it does not contact with the detection object when it is fixed.

Compared with the prior art, the above technical solution conceived by the present invention has the following beneficial effects by introducing a signal enhancement element to reflect and superimpose the ultrasonic guided wave:

1. Use the signal enhancement element to increase the amplitude of multiple echo signals of the defect when the primary echo signal of the defect is not obvious or the defect is in the detection blind area, which can not only improve the detection sensitivity of the guided wave, but also realize the defect detection without blind area ;

2. The attenuation module in the signal enhancement component can increase the attenuation of the sound wave and reduce the amplitude of the passing signal, thereby reducing the influence of other supporting structures of the pipeline under inspection on the detection signal;

3. By changing the installation position of the signal enhancement component, the detection area can be adjusted without moving other detection devices, which simplifies the detection process;

4. The structure of the signal enhancement element is simple, there is no need to modify the existing magnetostrictive guided wave detection device, and the cost of equipment improvement is low.

Description of drawings

Fig. 1 is the device schematic diagram that the present invention improves magnetostrictive guided wave detection sensitivity;

Fig. 2 is the device installation schematic diagram that improves magnetostrictive guided wave detection sensitivity in embodiment 1

3 is a schematic diagram of a three-dimensional structure of a signal enhancement element in Embodiment 2;

Fig. 4 is the working schematic diagram of the device improving the detection sensitivity of magnetostrictive guided wave in embodiment 3;

Fig. 5 is a waveform diagram of detection signals obtained by the device for improving the detection sensitivity of magnetostrictive guided waves in embodiment 3.

In all the drawings, the same reference numerals are used to denote the same elements or structures, among them: 1 - signal enhancement element 3 - excitation sensor 4 - receiving sensor 5 - detection object 6 - central processing unit 7 - signal generator 8 - Power Amplifier 9 - Signal Preprocessor 10 - A/D Converter 22 - Magnetizer 23 - Exciting Coil 24 - Receiving Coil 11 - Set Screw 12 - Housing 13 - Attenuation Module 14 - Partition 15 - Reflection Module 16 - Clamping bolt 17-transverse groove defect

detailed description

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not constitute a conflict with each other.

Figure 1 is a typical device for improving the sensitivity of magnetostrictive guided wave detection, including signal enhancement element 1, excitation sensor 3, receiving sensor 4, signal generator 7, power amplifier 8, signal preprocessor 9, A/D conversion device 10 and central processing unit 6; in practical applications, a magnetizer 22 and a receiving coil 24 are commonly used to form a receiving sensor 4, and a magnetizer 22 and an excitation coil 23 are used to form an excitation sensor 3; or only one magnetizer 22 and a coil are set, and the The duplexer is connected to the coil and performs the functions of receiving the sensor 4 and exciting the sensor 3 at the same time. The signal enhancement component 1 may only include the reflection module 15 , or may include the reflection module 15 and the attenuation module 13 at the same time.

According to the actual detection needs during installation, the detection area of the detection object 5 is first set, and two signal enhancement elements 1 are respectively installed at both ends of the detection area, wherein the reflection module 15 of the signal enhancement element 1 is arranged on the side close to the detection area . If one side of the detection area is located at the end of the detection object 5, the end can be used to perform the reflection function of the signal enhancement element 1, and only one signal enhancement element 1 is installed on the side of the detection area away from the end. The excitation sensor 3 is installed at one end of the detection area close to the reflection module 15 of the signal enhancement element 1; the reception sensor 4 can be installed at any position in the middle of the detection area according to the working conditions, or it can be close to the reflection module of another signal enhancement element 1 15 is installed at the other end of the detection area. Connect the input end of signal generator 7 and the output end of A/D converter 10 respectively with central processing unit 6; Signal generator 7 is connected with excitation sensor by power amplifier 8; Receiving sensor 4 is connected with A/D by signal preprocessor 9. The D converter 10 is connected, and the setting process of the device for improving the detection sensitivity of the magnetostrictive guided wave of the present invention is completed.

Because in the measurement process, the defect position cannot be predicted in advance. In the traditional magnetostrictive guided wave detection device, it is often necessary to adjust the position of the sensor to change the detection area, so as to know the specific position of the defect, and the operation is cumbersome. In the device of the present invention, the detection area is determined by the position of the signal enhancement element 1, and the detection area can be changed by adjusting the position of the signal enhancement element 1 on one side, or adjusting the positions of the signal enhancement elements 1 on both sides simultaneously, and the operation is relatively Simple.

During measurement, the central processor 6 controls the signal generator 7 to generate an excitation signal, which is input to the excitation sensor 3 through the power amplifier 8, and the ultrasonic guided wave is excited on the detection object 5 and propagates along the axial direction of the detection area; when the ultrasonic guided wave is propagating When encountering the defective part of the detection object 5, the echo signal is generated, which is superimposed and enhanced at the receiving sensor 4 by the reflection of the signal enhancement element 1; after the enhanced waveguide signal is received by the receiving sensor 4, it is processed The device 9 is connected to the A/D converter 10, and converted into a digital signal, which is input to the central processor 6; the central processor 6 generates a relationship curve between time and echo amplitude through the analysis of the digital signal, so as to know the defect position The distance from the receiving sensor 4 further obtains the position of the defect on the area to be detected.

According to another aspect of the present invention, there is also provided a signal booster element 1 for the above-mentioned device, which is characterized in that it includes an inner layer and an outer shell 12;

The inner layer includes a reflection module 15, and the inner layer is fixed radially on the outer surface of the detection object by the outer shell 12. The reflection module 15 exerts pressure on the joint with the detection object 5 to generate reversible deformation, which is used for reflection propagation Ultrasound guided waves passing through the site.

The shape of the inner surface of the signal enhancement element 1 is the same as that of the outer surface of the detection object 5, so as to ensure that the inner surface can be closely attached to the detection object 5 when fixed. For example, when the detection object 5 is tubular or rod-shaped, the inner surface of the signal enhancement element 1 is tubular.

When the detection object 5 is rod-shaped or tubular, the inner diameter of the inner layer is 0.1mm-2.0mm smaller than the outer diameter of the detection object 5, so as to ensure that it can be tightly combined with the detection object 5 when fixed.

Preferably, the inner layer further includes an attenuation module 13 arranged in parallel with the reflection module 15 in the axial direction, for absorbing the ultrasonic guided wave propagating inward from the outside of the detection area.

In order to ensure the reflection effect of the ultrasonic guided wave in the detection area, the material of the reflection module 15 is a hard metal or alloy, preferably steel, aluminum or copper; and to ensure the absorption effect of the signal enhancement element on the ultrasonic guided wave signal, The selection of the material of the attenuation module 13 is related to the absorption coefficient of the ultrasonic guided wave, preferably rubber, nylon or polytetrafluoroethylene.

Preferably, the inner layer further includes partitions 14, located at both ends of the inner layer, and between the attenuation module 13 and the reflection module 15, for fixing the attenuation module 13 and the reflection module 15 in the axial direction The thickness of the partition 14 is smaller than the thickness of the attenuation module 13 and the reflection module 15, so as to ensure that it does not contact the detection object 5 when it is fixed, so as not to affect the reflection and propagation of the ultrasonic guided wave.

For ease of installation, the partition plate 14, the attenuation module 13, the reflection module 15 and the housing 12 can all be composed of two or more parts. During installation, each part is arranged radially on the corresponding position of the detection object 5 and then fixed.

Example 1

The pipeline to be tested is shown in Figure 2, where point a to point d is a section of the pipeline to be tested with a length of 2m. Install the signal enhancement components at both ends of the area to be detected. The excitation sensor is installed at point a close to the signal enhancement component at the left end, and the receiving sensor is installed at point b. The distance from the signal enhancement component at the left end is L ₁ , and other components are also connected in sequence; defects The distance from the receiving sensor is L ₂ , and the distance from the signal enhancement element at the right end is L ₃ , then the amplitude of the first echo signal D1 of the defect can be expressed as

Among them, A ₀ is the amplitude of the excitation signal, A ₁ is the amplitude of the first echo signal D1 of the defect, R _D is the reflection coefficient of the defect, α is the attenuation coefficient of the guided wave propagating in the pipeline, and for this pipeline, α is 0.03 dB/m.

According to the propagation path of the guided wave, there are two propagation paths for the third echo signal of the defect, namely a→d→a→c→b and a→c→a→d→b. The amplitude of the echo signal after superposition can be expressed as

Among them, R _C is the reflection coefficient of the signal enhancement component.

Compared with the first echo signal of the defect, the amplitude enhancement factor n of the third echo signal of the defect can be expressed as

Among them, L is the set detection area length 2m. The reflection coefficient R _D of the defect in this embodiment is 0.1, and the reflection coefficient R _C of the signal enhancement element is 0.9, so the echo signal enhancement factor n in this embodiment is 1.41.

It can be seen from the above formula that the signal enhancement factor is related to the length of the detection area, the attenuation coefficient of the guided wave propagating in the pipeline, the reflection coefficient of the defect and the reflection coefficient of the signal enhancement component. The smaller the defect, the smaller the defect reflection coefficient RD, and the larger the enhancement factor _n , indicating that the signal enhancement method is more effective for small defect detection.

Example 2

FIG. 3 is a schematic structural diagram of a signal enhancement element for a tubular or rod-shaped object to be detected, including: an attenuation module 13 , a reflection module 15 , a partition 14 , and a housing 12 .

Wherein, the reflection module 15, the partition 14 and the attenuation module 13 jointly constitute the inner layer of the signal enhancement element 1, which is fixed on the outer surface of the object 5 to be detected by the outer shell, the material of the reflection module 15 is steel, and the material of the attenuation module 13 is rubber.

The reflection module 15 and the attenuation module 13 are arranged on the outer surface of the object to be detected 5, and three pairs of partitions 14 are respectively arranged between the reflection module 15 and the attenuation module 13, and at both ends of the inner layer of the signal enhancement element.

The attenuation module 13, the reflection module 15, the casing 12 and the three partitions 14 are all composed of upper and lower parts with the same shape. During installation, the upper casing 12 and the three upper partitions 14 will be fixed with 12 fastening bolts 11. Fix the lower casing 12 and the three lower partitions 14; then place the attenuation module 13 and the reflection module 15 on the corresponding parts of the detection object 5, wherein the reflection module is installed close to the detection area; finally cover the casing 12 on the attenuation module 13 And the outer side of the reflection module 15, and fix the upper and lower parts of the shell with six clamping bolts 16, that is, the installation process of the signal enhancement element 1 is completed. Since the inner diameters of the attenuation module 13 and the reflection module 15 are 1.0 mm smaller than the outer diameter of the object to be detected 5, they can be closely attached to the object to be detected 5 after being fixed, thereby causing the object to be detected to undergo reversible deformation to play a signal function. Enhancement. And because the thickness of the partition 14 is smaller than that of the attenuation module 13 and the reflection module 15, it does not directly contact with the object to be detected after installation, and will not affect the propagation of the ultrasonic guided wave on the object to be detected.

Example 3

Fig. 4 is according to the device working schematic diagram of improving magnetostrictive guided wave detection sensitivity of the present invention, and detection object 5 is the steel pipe of L 25mm, inner diameter 20mm, length L ₁ =2.8m, 0.5mm deep transverse groove defect 17 apart from pipeline The distance from the left end is L ₂ =0.8m, and the equivalent cross-sectional area loss is about 14.4%. A section of L ₃ =1.2m from the left end of the pipeline is set as the detection area. The device is equipped with a signal enhancement element 1 in Embodiment 2 at the right end of the detection area. The internal diameter of this element is 24mm, and its reflection module 15 is installed near the sensor 3 (4). The detection steps are as follows:

(1) The central processor controls the signal generator to generate an excitation signal, which is input to the excitation sensor 3 through a power amplifier, and is excited to generate an ultrasonic guided wave on the detection object 5, and propagates to the right;

(2) When the ultrasonic guide wave encounters the signal enhancement element, it generates the first echo signal C1 and the second echo signal C2; when it encounters the transverse groove defect 17, it generates the first echo signal D1, and the second echo signal Signal D2 and the third echo signal D3; when the ultrasonic guided wave encounters the right end of the detection object 5, an echo signal E is generated;

(3) The guided wave detection signal is connected to the A/D converter 10 through the signal preprocessor 9, and converted into a digital signal, and input to the central processing unit 6;

(4) After the central processor 6 receives the digital signal, the relationship curve between the time and the echo amplitude is obtained through analysis, as shown in FIG. 5 .

Fig. 5 is a waveform diagram of the detection signal obtained by the device for improving the detection sensitivity of the magnetostrictive guided wave. The three echo signals of the transverse groove defect 17 are D1, D2 and D3 respectively. Let the left end of the pipe be point a, the defect 17 of the transverse groove be point b, and the signal enhancement element at the right end be point c.

It can be seen that due to the attenuation of the pipeline, the amplitude of the first echo signal D1 of the transverse groove defect 17 is small, and it is in the rising stage of the signal, which is difficult to identify and brings difficulties to defect detection. If the distance between the transverse groove defect 17 and the receiving sensor 4 is less than 0.8m, that is, the first echo signal of the transverse groove defect 17 appears before 0.3ms, because it is in the detection blind zone, there will be missed detection. The propagation path of D2 is a→c→b→a. Since the propagation path is unique, the signal is not enhanced; D3 is formed by the superposition of two ultrasonic guided wave signals, and the propagation path of one of them is a→c→a→ b→a, and the other is a→b→a→c→a. Since the propagation distances of the two ultrasonic guided wave signals are exactly the same, waveform superposition occurs at the receiving sensor, which causes the amplitude of the defect echo signal to increase, from It can be seen from the figure that the signal amplitude of D3 is about 1.4 times of the amplitude of D1. While the first echo signal E at the right end of the pipeline passes through the attenuation module 13 of the signal enhancement element 1, the signal amplitude is reduced to 1/3 of the original value compared with the time when the signal enhancement element 1 is not set, which weakens its ability to detect the pipeline. influences. Since the enhancement of multiple echo signals of defects has nothing to do with the position of the area to be inspected where the defect is located, when the defect is in the detection blind area, the defect identification can still be carried out by observing the amplitude of multiple echo signals of the defect, and at the same time, it can be calculated according to the sound path of the guided wave Defect location.

It is easy for those skilled in the art to understand that the above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention, All should be included within the protection scope of the present invention.

Claims (5)

1. a kind of device for improving magnetic striction wave guide detection sensitivity, including stimulus sensor, reception sensor, signal occur Device, power amplifier, signal preprocessor, A/D converter and center processor；The signal generator is used to produce excitation Signal, the pumping signal input the stimulus sensor by the power amplifier, the excitation generation ultrasound in detection object Guided wave signals；The reception sensor is used to receive ultrasonic guided wave signals and is converted into detection signal, described in detection signal warp Signal preprocessor is sent to the A/D converter, and is converted into data signal；The center processor is used to control the letter Number generator produces pumping signal, and the data signal received in the A/D converter is used to analyze and process；Its feature exists In, in addition to signal enhancing element, the signal enhancing element include internal layer and shell；The internal layer includes reflecting module, institute State shell by internal layer from radially fixed in the outer surface of detection object so that reflecting module to detection object apply pressure, order inspection Survey object and produce reversible deformation；The material of the reflecting module is steel, aluminium or copper；The signal enhancing element internal layer include with it is anti- The attenuation module that module is set up in parallel in the axial direction is penetrated, for absorbing supersonic guide-wave.

2. device as claimed in claim 1, it is characterised in that the material of attenuation module is rubber in the signal enhancing element Glue, nylon or polytetrafluoroethylene (PTFE).

3. device as claimed in claim 1, it is characterised in that the signal enhancing element internal layer includes dividing plate；The dividing plate It is located at the both ends of internal layer respectively, and between attenuation module and reflecting module, for by the attenuation module and the reflection Module is fixed in the axial direction；The thickness of the dividing plate is less than the thickness of the attenuation module and the reflecting module, solid to ensure Timing does not contact with detection object.

4. a kind of method using such as any one of claim 1-3 described device raising magnetic striction wave guide detection sensitivity, its It is characterised by, comprises the following steps：

(1) two signal enhancing elements are arranged to the both ends in region to be detected, stimulus sensor and reception sensor are arranged at Between two signal enhancing elements, signal generator is connected by power amplifier with stimulus sensor, is received sensor and is passed through Signal preprocessor is connected with A/D converter, and center processor respectively connects the input and A/D converter of signal generator Output end；

(2) center processor control signal generator produces pumping signal, by power amplifier input stimulus sensor, is examining Survey excitation on object and produce supersonic guide-wave, and along the Propagation of the detection object；

(3) when supersonic guide-wave runs into the defects of detection zone, echo-signal is produced, the echo-signal is through signal enhancing element Reflection, it is superimposed and amplitude enhancing at sensor receiving；

(4) above-mentioned echo-signal inputs the A/D converter through signal preprocessor, and is converted into data signal；

(5) after center processor receives data signal, the position of defect is obtained by Treatment Analysis.

5. as claimed in claim 4 improve magnetic striction wave guide detection sensitivity method, it is characterised in that stimulus sensor with One of signal enhancing element is disposed adjacent.