Device and method for detecting and locating foaming defects of metal sandwich foam panels

Abstract

The present application discloses a device and method for detecting and locating foaming defects of metal sandwich foam panels. The detection and positioning device includes an ultrasonic guided wave excitation and receiving device, an ultrasonic guided wave detection probe, and a motor-driven XY cross-biaxial motion platform; the ultrasonic guided wave detection probe includes an excitation probe and four ultrasonic guided wave receiving probes, which are used to scan the outer surface of the test piece in the horizontal and vertical directions, and determine the position of the foaming defect of the test piece by comparing the change rate of the detection amplitude curve and the fitting amplitude curve based on the distance and amplitude change curve of the ultrasonic guided wave A-scan receiving signal. This technical solution can accurately locate the position of invisible defects, avoid irreversible damage to the test piece caused by sampling, and improve the efficiency and effectiveness of defect detection and positioning. It can reduce the detection steps of operators, reduce detection costs, and has high practical value in the field of industrial production and intelligent manufacturing.

Description

Technical Field

[0001] The present application relates to the technical field of non-destructive testing, and in particular to a device and method for detecting and locating foaming defects of metal sandwich foam panels. Background Art

[0002] Energy issues are a hot topic worldwide. China is vigorously promoting energy conservation and emission reduction. Using insulation materials for thermal insulation in industries like construction is an extremely effective energy-saving measure. The polyurethane metal sandwich insulation board industry is rapidly developing and is widely used in various fields. Polyurethane metal sandwich panels are used for home insulation, cold storage and cold chain logistics, and building insulation. Many applications utilize metal sandwich panels (aluminum, iron, or stainless steel). However, metal sandwich panels, such as polyurethane foam panels, often exhibit uneven foaming density during the foaming process due to production process issues, resulting in foaming defects in areas with lower foaming density. Metal sandwich panels with foaming defects not only fail to meet quality standards but also affect the safety of the finished product during subsequent assembly. Since polyurethane metal sandwich panels with different foaming conditions exhibit significant differences in insulation performance, this directly impacts the insulation effect. Furthermore, quantifying the maintenance, wear, and replacement time of insulation panels not only directly impacts company profits but also concerns order security. The use of new technology for real-time detection of foaming defects in metal sandwich panels is of great significance to the cold chain container logistics industry.

[0003] Currently, there's no proven method for locating foam defects in metal sandwich panels. Workers often rely on the percussion echo method to determine defect locations, a method with high error rates and high worker experience requirements. Designing a probe and method for locating foam defects in metal sandwich panels, effectively locating defects in sandwich panels with metal foam outer panels, is an urgent industrial challenge. Summary of the Invention

[0004] In view of this, the present application provides a device and method for detecting and locating foaming defects of metal sandwich foam panels, which can solve the problem in the prior art that the foaming defect positioning detection error of metal sandwich panels with outer panels is large and requires high worker experience.

[0005] In a first aspect, the present application provides a device for detecting and locating foaming defects of a metal sandwich foam panel, comprising an ultrasonic guided wave excitation and receiving device, an ultrasonic guided wave detection probe, and a motor-driven XY cross-biaxial motion platform;

[0006] The ultrasonic guided wave detection probe includes an excitation probe and four ultrasonic guided wave receiving probes, which are used to scan the outer surface of the test piece in the horizontal and vertical directions, and fit a distance-amplitude change curve based on the amplitude signal of the electromagnetic ultrasonic guided wave A-scan receiving signal. The position of the foaming defect of the test piece is determined by comparing the change rate of the detection amplitude curve with the fitted amplitude curve;

[0007] The motor directly drives the XY cross biaxial motion platform, which includes a motor and a cross guide slide driven by the motor. The ultrasonic guided wave receiving probe is connected to the end of the cross guide slide by a mechanical structure, and the ultrasonic guided wave excitation probe is connected to the cross intersection of the guide slide and is configured to switch the motion track and excitation direction.

[0008] Optionally, each pair of ultrasonic guided wave detection probes is connected in a one-transmit-one-receive manner. When each pair of ultrasonic guided wave detection probes performs one-transmit-one-receive detection, each pair of probes is placed at relative positions on the same side and maintains a certain distance within the optimal signal attenuation range.

[0009] Optionally, the motor directly driven XY cross dual-axis motion platform includes a square platform frame and a cross axis, the motion track is set on the four sides of the square platform frame, and the cross axis is set in the square platform frame, characterized in that the cross axis includes an X-axis and a Y-axis, and the XY axis is a dual axis.

[0010] Optionally, the outer plate material of the metal sandwich foam panel is one of 1mm to 3mm steel plate and aluminum plate.

[0011] Optionally, the signal distance-amplitude variation curve obtained by fitting the A-scan received signal at a defect-free location is defined as follows:

[0012] y1=kx a +b,0 <a<1,x> 0

[0013] y2=k(lx) a +b,0 <a<1,x> 0

[0014] Where y1 and y2 are the signal amplitudes of the two receiving probes, x is the distance from the excitation probe to the first receiving probe, l is the distance between the two receiving probes, and b, k, and a are all constants.

[0015] The signal distance-amplitude change curve of the A-scan receiving signal during defect detection is defined as follows:

[0016] y3=kx a +b1,0 <a<1,x> 0

[0017] y4=k(lx) a +b2,0 <a<1,x> 0

[0018] Where y3 and y4 are the signal amplitudes of the two receiving probes, x is the distance from the excitation probe to the first receiving probe, l is the distance between the two receiving probes, b, k, and a are all constants. When the defect is on one side of the excitation probe:

[0019] b 1,2 =b+b x

[0020] b x is the effect of the complete defect on the received amplitude, and the other side is b;

[0021] When the excitation probe moves on the X or Y axis and contacts the edge of the defect, its distance-amplitude curve will change. The curve change rate W is defined as follows:

[0022]

[0023]

[0024] When W1 or W2 starts to change, it is the defect boundary, and when it stops changing, it is the other boundary of the defect. This can locate the boundary of the defect in the uniaxial direction.

[0025] In a second aspect, the present application provides a method for detecting foaming defects in metal sandwich foam panels, using a probe as described above for defect location detection of metal sandwich panels. When using a one-transmit-one-receive detection method, the four ultrasonic guided wave receiving probes are mechanically connected to the ends of a cross guide rail slide, and the ultrasonic guided wave excitation probe is connected to the cross intersection of the guide rail slide to switch the motion track and excitation direction, and a constant distance is maintained between the guided wave excitation probe and the guided wave receiving probe;

[0026] A high-frequency pulse excitation signal is loaded into the waveguide excitation probe, and the waveguide signal propagated from the outer plate is received by the waveguide receiving probe.

[0027] One or more technical solutions provided in this application have at least the following technical effects or advantages:

[0028] In order to perform non-destructive testing to locate foaming defects in metal sandwich panels with outer panels, this application uses a Lamb wave ultrasonic waveguide probe based on the Lorentz force, which can smoothly generate high-frequency vibrations in the outer panels due to the magnetic and electrical conductivity characteristics of the outer panels. The electromagnetic ultrasonic waveguide probe used in this application does not require the use of coupling agents, has a simpler structure, and is more convenient to detect, making it suitable for conventional panel testing. At the same time, in order to enhance the waveguide capability in the outer panels, highly magnetized neodymium iron boron permanent magnets are used. The magnetic flux density of the permanent magnet sheet is high, which can effectively achieve the enhancement effect. This application can locate and detect foaming defects in metal sandwich panels with outer panels. When the probe provided by this application is applied to the inspection of metal refrigerated containers, it can be simple to operate and highly efficient without damaging the appearance of the container. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The following detailed description of the specific embodiments of the present application in conjunction with the accompanying drawings will make the technical solutions and other beneficial effects of the present application apparent.

[0030] Figure 1 A schematic diagram of the structure of an ultrasonic guided wave probe for locating and detecting foaming defects in metal sandwich panels provided in an embodiment of the present application;

[0031] Figure 2 A schematic diagram of a structure of a probe for locating and detecting foaming defects in metal sandwich panels provided in an embodiment of the present application, mounted on a motor-driven XY cross-biaxial motion platform;

[0032] Figure 3 The received signal of an electromagnetic ultrasonic guided wave probe for locating and detecting foaming defects in metal sandwich panels provided by an embodiment of the present application;

[0033] Figure 4 The invention provides an electromagnetic ultrasonic guided wave probe for locating and detecting foaming defects in metal sandwich panels provided in an embodiment of the present application to obtain the foaming defect location status of the entire panel. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the embodiments described are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative efforts are within the scope of protection of this application.

[0035] In the description of this application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the described features. In the description of this application, "plurality" means two or more, unless otherwise specifically defined.

[0036] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections, electrical connections, or mutual communication; they can refer to direct connections or indirect connections through an intermediate medium; they can refer to internal communication between two components or the interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0037] The disclosure below provides many different embodiments or examples for realizing different structures of the present application. In order to simplify the disclosure of the present application, the components and settings of specific examples are described below. Of course, they are merely examples and are not intended to limit the present application. In addition, the present application may repeat reference numbers and / or reference letters in different examples, and such repetition is for the purpose of simplicity and clarity, and does not itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present application provides examples of various specific processes and materials, but those of ordinary skill in the art will appreciate the application of other processes and / or the use of other materials.

[0038] Example 1

[0039] This embodiment 1 provides a device for detecting and locating foaming defects of a metal sandwich foam board, see Figure 1 and Figure 2, including: ultrasonic guided wave excitation and receiving device, ultrasonic guided wave detection probe, motor-driven XY cross-biaxial motion platform, probe housing, cable and connector; each pair of detection probes is one transmitting and one receiving, and adopts electromagnetic ultrasonic guided wave probe detection, wherein four ultrasonic guided wave receiving probes are connected to the end of the cross guide rail slide by a mechanical structure, and the ultrasonic guided wave excitation probe is connected to the cross intersection of the guide rail slide to switch the motion track and excitation direction, and the guided wave propagation coverage range is the detection area. The detection probe is driven by a motor to move the probe left and right in the XY direction on the slide rail. The edge of the probe housing is rectangular, and the detection probe signal is vertically incident on the outer surface of the material plate; the ultrasonic guided wave detection probe is located at the bottom of the probe housing, and the motor-driven XY cross-biaxial motion platform is connected to the cross guide rail slide by a stepper motor control device through a cable.

[0040] The probe is used for performing non-destructive testing on the location of foaming defects in a metal sandwich panel, wherein the outer panels of the metal sandwich panel are metal outer panels.

[0041] The detection probe is tightly fitted to the lower surface of the probe housing and the lower surface of the permanent magnet.

[0042] The outer plate material of the metal sandwich panel is one of 1mm-3mm steel plate, aluminum plate or other metal plates.

[0043] The electromagnetic ultrasonic guided wave probe provided in this embodiment has the characteristics of non-contact and non-harmful. Electromagnetic ultrasonic guided waves have the advantages of long propagation distance, low energy attenuation and large detection range. They are widely used in non-destructive testing of plate structures and can greatly improve the detection efficiency. In addition, it is difficult to locate the detected defects. For large detection objects, accurate flaw detection can be achieved, which can reduce the cost of defect detection and repair. At the same time, the electromagnetic ultrasonic guided wave probe can effectively enhance the guided wave energy in the outer plate of the metal sandwich panel and compensate for the attenuation of the guided wave by the core material in the metal sandwich panel. Defect positioning and flaw detection are easy, the detection efficiency is high, and the operation is simple. Compared with other existing methods, it is a non-destructive detection positioning method.

[0044] Example 2

[0045] This embodiment provides a method for locating and detecting foaming defects in metal sandwich panels. Compared with the elliptical positioning method of traditional guided wave ultrasonic defect detection, this method can realize damage positioning detection of metal sandwich panels without considering material parameter information and dispersion relationship in the detection, and is not affected by the anisotropic characteristics of metal sandwich panels. Guided waves have multimodal characteristics in the structure and are affected by the dispersion effect. Their signals are complex and difficult to analyze. Narrowband excitation is relatively less affected by dispersion, the waveform distortion is not significant, and the signal is simple and conducive to analysis. According to the calculation based on the signal amplitude density plot, the detection probe preferably uses a peak wave narrowband signal modulated by a Hanning window as the excitation signal to excite the Lamb wave of the A0 mode with a larger off-plane displacement, as shown in the following formula:

[0046]

[0047] Where: A is the amplitude of the excitation signal; f is the center frequency; n is the peak wave number.

[0048] The guided wave ultrasonic probe has the advantages of being sensitive to small defects and damage in metal sandwich foam board structures and easy to achieve automated scanning and positioning, and can transmit long distances in the structure. After adjusting the receiving probe according to the calculated detection distance, it is installed at the four ends of the motor-driven XY cross dual-axis motion platform. The excitation probe is installed in the middle of the cross. A signal transmitter is used to apply a rectangular pulse wave with a cycle number of 5 as the excitation signal. The stepper motor is used to drive the XY axis of the motion axis in turn, and the workpiece plate is divided into equally spaced areas to be inspected, thereby changing the position of the excitation receiving probe, and collecting a receiving signal at each position of the X and Y axes.

[0049] like Figure 3 As shown in the figure, during testing, two electromagnetic ultrasonic guided wave probes are placed at each end of the XY axis on the outer surface of the metal sandwich panel, maintaining a constant distance. A high-frequency pulse excitation signal is applied to the excitation probe, and the other two probes receive the guided wave signal transmitted from the outer panel.

[0050] In order to verify the effectiveness of the electromagnetic ultrasonic guided wave probe provided by the present invention in locating foaming defects in metal sandwich panels, the probe provided by the present invention was placed on the metal sandwich panels to perform foaming defect location measurement and obtain corresponding detection data. Figure 4 In order to use the electromagnetic ultrasonic guided wave probe to receive the signal, the workpiece is divided into equally spaced areas to be inspected. Using the characteristics of the received ultrasonic signal, the signal distance amplitude of the defect-free inspection area is first calibrated. The curve is defined as follows:

[0051] y1=Kx a +b,0 <a<1,x> 0

[0052] y2=k(lx) a +b,0 <a<1,x> 0

[0053] Where y1 and y2 are the signal amplitudes of the two receiving probes, x is the distance from the excitation probe to the first receiving probe, l is the distance between the two receiving probes, and b, k, and a are all constants.

[0054] Then, the foaming of the metal sandwich panel is detected: the signal distance-amplitude change curve of the A-scan receiving signal during defect detection is defined as follows:

[0055] y3=kx a +b1,0 <a<1,x> 0

[0056] y4=k(lx) a +b2,0 <a<1,x> 0

[0057] Where y3 and y4 are the signal amplitudes of the two receiving probes, x is the distance from the excitation probe to the first receiving probe, l is the distance between the two receiving probes, b, k, and a are all constants. When the defect is on one side of the excitation probe:

[0058] b 1,2 =b+b x

[0059] b x is the effect of the complete defect on the received amplitude, and the other side is b.

[0060] When the excitation probe moves on the X or Y axis and contacts the edge of the defect, its distance-amplitude curve will change. The curve change rate W is defined as follows:

[0061]

[0062]

[0063] When W1 or W2 starts to change, it is the defect boundary, and when it stops changing, it is the other boundary of the defect. In this way, the boundary of the defect in the uniaxial direction can be located.

[0064] by Figure 4For example, when the detection probe is in a defect-free position, the distance-amplitude curve of the A-scan received signal changes similarly to the curve during calibration, affected only by a slight error. With a curve change rate of W = 0.02, the system determines that there is no defect. When the detection probe sweeps across the defect boundary in the X-axis direction, the amplitude of the distance-amplitude curve of the A-scan received signal changes to a certain extent based on the geometry of the defect. At this time, W = 0.3, and the system determines that it has passed through the defect. Similarly, in the Y-axis direction, the amplitude changes to varying degrees when passing through defect boundaries of different shapes, with W = 0.5 and W = 0.8 respectively. When the detection probe completely sweeps across the defect, the signal distance-amplitude curve follows a pattern that is essentially the same as during calibration, and the system continues detection.

[0065] It can be seen that the electromagnetic ultrasonic guided wave probe has a stronger anti-interference ability for receiving signals, smaller signal noise, no signal processing is required during analysis, and the signal reception amplitude is large, which is convenient for observing and locating defects in metal sandwich panels. The electromagnetic ultrasonic guided wave probe can be used to non-destructively detect the location of defects in metal sandwich panels and greatly improve detection efficiency.

[0066] The above is only a preferred specific implementation method of the present application, but the scope of protection of the present application is not limited thereto. Any changes or replacements that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed in this application should be covered by the scope of protection of the present application.

Claims

1. A device for detecting and locating foaming defects of metal sandwich foam panels, characterized in that: It includes ultrasonic guided wave excitation and receiving devices, ultrasonic guided wave detection probes, and motor-driven XY cross-axis motion platform; The ultrasonic guided wave detection probe includes an excitation probe and four ultrasonic guided wave receiving probes, which are used to scan the outer surface of the test piece in the horizontal and vertical directions, and fit a distance-amplitude change curve based on the amplitude signal of the electromagnetic ultrasonic guided wave A-scan receiving signal. The position of the foaming defect of the test piece is determined by comparing the change rate of the detection amplitude curve with the fitted amplitude curve; The motor directly drives the XY cross-axis motion platform, which includes a motor and a cross-guide slide driven by the motor. The ultrasonic guided wave receiving probe is connected to the end of the cross-guide slide by a mechanical structure, and the ultrasonic guided wave excitation probe is connected to the cross intersection of the guide slide and is configured to switch the motion track and excitation direction. The signal distance-amplitude variation curve fitted by the A-scan received signal at the defect-free location is defined as follows: Where y1 and y2 are the signal amplitudes of the two receiving probes, x is the distance from the excitation probe to the first receiving probe, l is the distance between the two receiving probes, and b, k, and a are all constants. The signal distance-amplitude change curve of the A-scan receiving signal during defect detection is defined as follows: Where y3 and y4 are the signal amplitudes of the two receiving probes, x is the distance from the excitation probe to the first receiving probe, l is the distance between the two receiving probes, b, k, and a are all constants. When the defect is on one side of the excitation probe: bx is the effect of the complete defect on the received amplitude, and b is the other side; When the excitation probe moves on the X or Y axis and contacts the edge of the defect, its distance-amplitude curve will change. The curve change rate W is defined as follows: When W1 or W2 starts to change, it is the defect boundary, and when it stops changing, it is the other boundary of the defect. In this way, the boundary of the defect in the uniaxial direction can be located.

2. The detection and positioning device according to claim 1, characterized in that: Each pair of ultrasonic guided wave detection probes is connected in a one-transmitting and one-receiving manner. When each pair of ultrasonic guided wave detection probes performs one-transmitting and one-receiving detection, each pair of probes is placed at relative positions on the same side and maintains a certain distance within the optimal signal attenuation range.

3. The detection and positioning device according to claim 1, characterized in that: The motor direct-driven XY cross dual-axis motion platform includes a square platform frame and a cross axis. The motion tracks are set on the four sides of the square platform frame. The cross axis is set in the square platform frame. It is characterized in that the cross axis includes an X axis and a Y axis, and the XY axis is a dual axis.

4. The detection and positioning device according to claim 1, characterized in that: The outer plate material of the metal material sandwich foam board is one of 1 mm ~ 3 mm steel plate and aluminum plate.

5. A method for detecting foaming defects of metal sandwich foam panels, characterized in that: A detection and positioning device for foaming defects of a metal sandwich foam panel according to any one of claims 1 to 4 is used. When using a one-transmit-one-receive detection, the four ultrasonic guided wave receiving probes are connected to the ends of a cross guide rail slide by a mechanical structure, and the ultrasonic guided wave excitation probe is connected to the cross intersection of the guide rail slide to switch the motion track and excitation direction, and a constant distance is maintained between the guided wave excitation probe and the guided wave receiving probe; A high-frequency pulse excitation signal is loaded into the waveguide excitation probe, and the waveguide signal propagated from the outer plate is received by the waveguide receiving probe.

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