Method for manufacturing ultrasonic flaw detection test block and ultrasonic flaw detection test block

Abstract

The present invention provides a method for manufacturing an ultrasonic flaw detection test block and an ultrasonic flaw detection test block, wherein the manufacturing method comprises the following steps: sequentially paving a lower composite material layer and an upper composite material layer of a defect placeholder plate; a curing step; removing the top and / or bottom surface materials of the cured test block blank according to the design size and ensuring that the top and / or bottom surface after the material is removed and the design defect placeholder plate form a preset angle a on a projection of a preset plane, a≠0°, and at least one edge of the design defect placeholder plate is exposed on the top and / or bottom surface after the material is removed; and a placeholder plate extraction step. When the present invention performs ultrasonic detection on the top or bottom surface of the finally formed ultrasonic flaw detection test block, the depth of the design defect is continuously and uninterruptedly distributed in the extension direction of the design defect, and there is no step jump in the depth of the detection defect, thereby realizing continuous detection of the depth of the detection defect within the height range of the ultrasonic flaw detection test block, and the accuracy of the depth detection result is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of composite material nondestructive testing equipment, and in particular relates to a method for manufacturing an ultrasonic flaw detection test block and the ultrasonic flaw detection test block. Background Art

[0002] The damage forms of composite laminates include delamination and impact damage. In order to determine the damage depth of the composite layer, the prior art mostly uses the ultrasonic reflection method. In order to calibrate the corresponding ultrasonic device or compare the depth data of ultrasonic flaw detection, it is necessary to make an ultrasonic flaw detection test block in the prior art. For example, the prior art publication number CN110108793A discloses a method for testing the damage depth of a composite laminate structure, in which a comparison test block is specifically disclosed. However, in the test block, each defect is pre-embedded between different layers of prepreg, that is, in the height direction of the test block, each defect has a corresponding relationship with the paved prepreg layer, so that when defects occur at different layers, the specific position (number of layers) of the defect can be accurately located. However, due to the characteristics of the composite molding process, the "layer" attribute of the product is no longer obvious, because a large amount of resin glue is separated during curing, and the product needs to be processed to a suitable thickness after curing, and the number of layers processed cannot be determined. Therefore, the comparison test block for testing the damage depth of the composite laminate structure is made by layer, and the application range is very narrow, and the result is inaccurate. More importantly, the comparison test blocks in the prior art have multiple design defects, which simulate corresponding specific stratification defects. The positions of these design defects are in the height direction of the test blocks. The height of each design defect (which can be understood as the simulated defect depth during detection) is discrete and discontinuous, and does not completely correspond to the actual random defect occurrence depth of the test piece. Therefore, when the comparison test blocks in the prior art are used to calibrate the ultrasonic device or compare the flaw detection results of the test piece, the depth detection results are not accurate. Summary of the invention

[0003] Therefore, the present invention provides a method for manufacturing an ultrasonic flaw detection test block and an ultrasonic flaw detection test block to solve the problem in the related art that the discrete discontinuity of the defect depths at multiple designed depths in the flaw detection test block does not completely correspond to the actual random occurrence depths of the defects in the test piece, and the depth detection result is not accurate.

[0004] In order to solve the above problems, the present invention provides a method for manufacturing an ultrasonic flaw detection test block, comprising the following steps:

[0005] Prepreg layer laying step: firstly, laying multiple prepreg layers to form a lower composite material layer, laying a design defect placeholder plate on the top surface of the lower composite material layer, and then laying multiple prepreg layers on the top surface of the design defect placeholder plate to form an upper composite material layer, and the lower composite material layer, the design defect placeholder plate and the upper composite material layer after laying are formed into a test block blank;

[0006] A curing step, curing the test block body;

[0007] A machining step, removing the top and / or bottom material of the solidified test block blank according to the design size and ensuring that the top and / or bottom surface after the material is removed forms a preset angle a with the projection of the design defect placeholder on a preset plane, a≠0°, and at least one edge of the design defect placeholder is exposed on the top and / or bottom surface after the material is removed;

[0008] The step of extracting the placeholder plate is to extract the design defect placeholder plate from the test block blank to form an ultrasonic flaw detection test block.

[0009] In some embodiments, the design defect placeholder is a metal foil or a polyethylene film.

[0010] In some embodiments, when laying the design defect placeholder, a release agent is applied to the side of the design defect placeholder facing the lower composite material layer and the upper composite material layer.

[0011] In some embodiments, the curing step is performed in an autoclave, the curing temperature is 110° C. to 160° C., and the curing time is 8 h to 12 h.

[0012] In some embodiments, before the curing step, the method further comprises:

[0013] In the vacuum shaping step, the outer periphery of the test block blank is wrapped with air-permeable felt and then placed in a vacuum bag to evacuate the air.

[0014] In some embodiments, after the step of extracting the design defect placeholder, the method further includes:

[0015] The waterproof layer construction step is to apply waterproof glue on the outer surface of the ultrasonic flaw detection test block.

[0016] In some embodiments, the thickness of the design defect placeholder is d, 0.5 mm ≤ d ≤ 3 mm; and / or the design size is the same as the size of the test piece.

[0017] In some embodiments, the design defect placeholder has a plurality of rectangular comb teeth of different widths.

[0018] In some embodiments, 5°≤a≤30°.

[0019] The present invention also provides an ultrasonic flaw detection test block, which is manufactured by adopting the manufacturing method of the ultrasonic flaw detection test block as mentioned above.

[0020] The present invention provides a method for manufacturing an ultrasonic flaw detection test block and an ultrasonic flaw detection test block. In the ultrasonic flaw detection test block, only one layer of design defect placeholder plate is used to realize the structure of the design defect therein. The corresponding material is removed by machining the top surface and / or the bottom surface of the formed test block blank so that a preset angle a is formed between the plane of the design defect and the top surface and / or the bottom surface, that is, the two are not parallel. Therefore, when ultrasonic testing is performed on the top surface or the bottom surface of the finally formed ultrasonic flaw detection test block, the depth of the design defect is continuously and uninterruptedly distributed in the extension direction of the design defect, and there is no step jump in the depth of the detection defect, thereby realizing continuous detection of the depth of the detection defect within the height h range of the ultrasonic flaw detection test block, and the accuracy of the depth detection result is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic flow chart of a method for manufacturing an ultrasonic flaw detection test block according to an embodiment of the present invention;

[0022] Figure 2 It is a schematic structural diagram of a test block blank before machining formed in an embodiment of the present invention;

[0023] Figure 3 for Figure 2 A schematic diagram of the structure of an ultrasonic testing test block formed after the test block blank is processed according to the designed dimensions;

[0024] Figure 4 The figure is a schematic diagram of a specific structure of a design defect placeholder in an embodiment of the present invention.

[0025] The reference numerals are:

[0026] 1. Lower composite material layer; 2. Design defect placeholder plate; 3. Upper composite material layer; 100. Test block blank; 200. Ultrasonic flaw detection test block. DETAILED DESCRIPTION

[0027] See also Figures 1 to 4 As shown, according to an embodiment of the present invention, a method for manufacturing an ultrasonic flaw detection test block is provided, comprising the following steps:

[0028] Prepreg layer laying step, first laying multiple prepreg layers to form a lower composite material layer 1, laying a layer of design defect placeholder plate 2 on the top surface of the lower composite material layer, then laying multiple prepreg layers on the top surface of the design defect placeholder plate 2 to form an upper composite material layer 3, the lower composite material layer 1, the design defect placeholder plate 2 and the upper composite material layer 3 after laying form a test block blank 100, that is, only one layer of design defect placeholder plate 2 is laid in the test block blank 100;

[0029] A curing step, curing the test block blank 100 to form the test block blank 100 into a solid state with a reliable and stable structure;

[0030] Machining step, removing the top and / or bottom material of the solidified test block blank 100 according to the design size and ensuring that the top and / or bottom surface after the material is removed forms a preset angle a with the projection of the design defect placeholder plate 2 on a preset plane, a≠0°, and at least one edge of the design defect placeholder plate 2 is exposed on the top and / or bottom surface after the material is removed;

[0031] The step of extracting the placeholder plate is to extract the design defect placeholder plate 2 from the test block blank 100 from the edge of one side where the design defect placeholder plate 2 is exposed to form the ultrasonic flaw detection test block 200.

[0032] In this technical solution, only one layer of design defect placeholder plate 2 is used in the ultrasonic flaw detection test block 200 to realize the construction of the design defect therein, and the corresponding material is removed by machining the top surface and / or bottom surface of the formed test block blank 100 so that a preset angle a is formed between the plane of the design defect and the top surface and / or bottom surface, that is, the two are not parallel, so that when the top surface or bottom surface of the finally formed ultrasonic flaw detection test block 200 is ultrasonically inspected, the depth of the design defect is continuously and uninterruptedly distributed in the extension direction of the design defect, and there is no step jump in the depth of the detection defect, thereby realizing continuous detection of the depth of the detection defect within the height h range of the ultrasonic flaw detection test block 200, and the accuracy of the depth detection result is improved.

[0033] The aforementioned prepreg layer is specifically formed by immersing fabric in a resin raw material, wherein the resin raw material can be selected from one or more of phenolic resin and epoxy resin; the fabric can be selected from one of carbon fiber, glass fiber, and aramid fiber, and the thickness of the lower composite material layer 1 and the upper composite material layer 3 and the material distribution of each layer are consistent with the thickness of the test piece and the laying of each layer.

[0034] In a preferred embodiment, the aforementioned design dimensions are the same as the dimensions of the test piece. For example, the test piece is a rectangular composite material block. The length and width of the top surface of the ultrasonic flaw detection test block 200 are equal to the length and width of the top surface of the test piece, and the length and width of the bottom surface of the ultrasonic flaw detection test block 200 are equal to the length and width of the bottom surface of the test piece. The height between the top and bottom surfaces of the two is also completely equal. In this way, the actual position and depth of the defects in the test piece can be completely matched, and the test results are more accurate. It can be understood that the aforementioned identical dimensions are ensured by the material removal step of machining. Specifically, see Figure 2 As shown in the figure, a test block blank 100 after paving and curing is completed. Specifically, a polyethylene film is first laid on the upper plane of the mold and a release agent is coated on the top surface of the film. Then, 5 layers of prepreg layers are continuously laid on the top surface of the film, and then a layer of design defect placeholder 2 is continuously laid on the top surface of the 5th layer. Then, 5 layers of prepreg layers are continuously laid on the top surface of the design defect placeholder 2. Then, the formed test block blank 100 is separated from the aforementioned polyethylene film and subjected to a curing step to form a cured test block blank 100. At this time, the test block blank 100 is machined, for example, Figure 2 In the orientation shown, first, part of the material of the lower composite material layer 1 is removed in sequence from the bottom surface toward the top surface to form a bottom surface that forms an angle a with the design defect occupying plate 2. At this time, in theory, ultrasonic flaw detection can be performed after a coupling agent (such as water, etc.) is sprayed on the bottom surface to obtain corresponding images of defects at different positions and depths. The image can be used as a reference figure when performing ultrasonic flaw detection on the inspected part, and of course, it can also be used as a calibration figure for the ultrasonic flaw detection equipment; and as shown in FIG. Figure 2 and Figure 3 As shown, you can also Figure 2 The top surface of the test block blank 100 in the embodiment is removed from the top surface to the bottom surface in sequence to form a top surface that forms an angle a with the designed defect occupying plate 2. In theory, the top surface can also be used as an ultrasonic detection surface. The top surface or the bottom surface is used as the ultrasonic detection surface, and the defect depth conversion principle is exactly the same, see Figure 3As shown, taking the bottom surface as the ultrasonic testing surface as an example, the ultrasonic probe is directed from the exposed design defect on the bottom surface toward one side edge of the lower composite material layer 1 (defined as the lower side edge) as the testing starting point, and from left to right, the probe will obtain the vertical distance hc between each testing point on the bottom surface and the lower side edge of the design defect (that is, the probe should maintain an inclined angle a with the bottom surface during the testing process to be perpendicular to the lower side edge). At this time, the height h of the ultrasonic flaw detection test block 200 and the projection length s of the design defect on the bottom surface are known quantities, so. From the geometric relationship, it can be seen that the defect depth hc' that should be detected at the position l of the probe during ultrasonic testing is theoretically the same as the designed defect depth hc. If they are different, calibration is required.

[0035]

[0036] Of course, based on the consistency requirements of the size with the test piece, it is also necessary to Figure 2 The left side surface and the right side surface of the test block blank 100 are shown to be machined.

[0037] In some embodiments, the design defect placeholder 2 is a metal foil or a polyethylene film. Preferably, a metal foil, such as an aluminum foil, a stainless steel foil, or the like, is used. The metal foil has a certain mechanical strength, which can prevent the design defect placeholder 2 from being deformed during the manufacturing process of the test block, causing the final design defect position to deviate from the design position, thereby reducing the calibration or comparison accuracy. In some working conditions where the accuracy requirement is not high and a variety of defect shapes are desired, a polyethylene film can be used to form the design defect placeholder 2. The polyethylene film itself has anti-adhesion properties, and a release agent does not need to be applied. It can be left in the test block, which can simplify the process and reduce costs. In order to ensure the accuracy of the final test results, a design defect placeholder 2 made of a metal foil is preferably used. At this time, when the design defect placeholder 2 is laid, a release agent is applied to the side of the design defect placeholder 2 facing the lower composite material layer 1 and the upper composite material layer 3 to facilitate the smooth demolding of the metal foil.

[0038] The curing step is carried out in an autoclave, the curing temperature is 110°C to 160°C, and the curing time is 8h to 12h. Below this range, the material strength is insufficient, and above this range, the material properties do not change much, reducing production efficiency.

[0039] In some embodiments, before the curing step, it also includes: a vacuum shaping step, in which the periphery of the test block blank 100 is wrapped with breathable felt and then placed in a vacuum bag for evacuation, so as to discharge the air dissolved in each prepreg layer, thereby preventing the air from expanding due to heat in the subsequent curing step and causing structural defects inside the test block, thereby affecting the test results. The aforementioned breathable felt can ensure the smooth removal of the aforementioned air and prevent adhesion between the test block blank 100 and the vacuum bag.

[0040] When ultrasonic flaw detection is performed on the ultrasonic flaw detection test block 200, it is necessary to spray a coupling agent on at least the detection surface, generally using water. Therefore, in order to increase the service life of the test block, in a preferred embodiment, after the step of extracting the placeholder plate, it also includes: a waterproof layer construction step, in which waterproof glue (specifically, epoxy waterproof glue) is applied on the outer surface of the ultrasonic flaw detection test block 200 to form a waterproof layer on the outer peripheral surface of the ultrasonic flaw detection test block 200. It should be noted that the thickness of the design defect placeholder plate 2 is d, and the thickness is often small, for example, 0.5mm≤d≤3mm. When the waterproof glue is applied to the outer peripheral surface of the ultrasonic flaw detection test block 200, the exposed end of the design defect can be blocked to prevent the coupling agent from entering the design defect. The design defect placeholder plate 2 has a plurality of rectangular comb teeth of different widths, see Figure 4 As shown, in a specific embodiment, the design defect occupying plate 2 has rectangular teeth with widths of 0.5mm, 1mm, 1.5mm and 2mm, so that the width of the design defect can correspond to the actual defect width that often occurs in the part to be inspected, thereby further improving the accuracy of the ultrasonic flaw detection result. Specifically, in terms of the paving relationship, to ensure Figure 4 The design defect in the left or right end of the spacer 2 is Figure 3 The left or right end of the design defect in the ultrasonic flaw detection can be made along the Figure 3 The ultrasonic testing surface shown moves left and right to obtain the depth of different positions under a specific defect width.

[0041] In some embodiments, 5°≤a≤30°. Specifically, when the value of a is too large, the inclination of the bottom surface or the top surface becomes more severe, and a too steep inclination is not conducive to the contact operation of the ultrasonic probe, and the detection operation of the ultrasonic probe is inconvenient; when the value of a is too small, the length of the ultrasonic flaw detection test block 200 may be designed to be too large, which is not convenient for use. When the value of a is within the aforementioned range, the convenience of the detection operation of the ultrasonic probe and the compactness of the structure of the ultrasonic flaw detection test block 200 and the improvement of portability can be taken into account.

[0042] Machining may specifically be grinding, milling or cutting.

[0043] The present invention also provides an ultrasonic flaw detection test block, which is manufactured by adopting the manufacturing method of the ultrasonic flaw detection test block as mentioned above.

[0044] It is easy for those skilled in the art to understand that, without conflict, the advantageous technical features of the above-mentioned methods can be freely combined and superimposed.

[0045] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention shall be included in the protection scope of the present invention. The above are only preferred embodiments of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and variations can be made without departing from the technical principles of the present invention, and these improvements and variations should also be regarded as the protection scope of the present invention.

Claims

1. A method for making an ultrasonic flaw detection test block, characterized in that: The following steps are involved: Prepreg layer laying step: firstly laying multiple prepreg layers to form a lower composite material layer (1), laying a layer of design defect placeholder plate (2) on the top surface of the lower composite material layer, then laying multiple prepreg layers on the top surface of the design defect placeholder plate (2) to form an upper composite material layer (3), and the lower composite material layer (1), the design defect placeholder plate (2) and the upper composite material layer (3) after laying are formed into a test block blank (100); a curing step, curing the test block blank (100); a machining step, removing material from the top and / or bottom surfaces of the solidified test block blank (100) according to the design dimensions, so that the top and / or bottom surfaces of the test block blank (100) form a preset angle a with the design defect placeholder (2), a≠0°, and at least one edge of the design defect placeholder (2) is exposed on the top and / or bottom surfaces after the material is removed; The step of extracting the placeholder plate, wherein the design defect placeholder plate (2) is extracted from the test block blank (100) to form an ultrasonic flaw detection test block (200), enables the depth of the design defect to be continuously and uninterruptedly distributed in the extension direction of the design defect when ultrasonic testing is performed on the top surface or the bottom surface of the finally formed ultrasonic flaw detection test block (200), without any step jump in the depth of the detected defect.

2. The method according to claim 1, characterized in that: The design defect placeholder plate (2) is a metal foil or a polyethylene film.

3. The production method according to claim 1 or 2, characterized in that: When laying the design defect placeholder plate (2), a release agent is applied to the side surfaces of the design defect placeholder plate (2) facing the lower composite material layer (1) and the upper composite material layer (3).

4. The method according to claim 1, characterized in that: The curing step is carried out in an autoclave, the curing temperature is 110° C. to 160° C., and the curing time is 8 h to 12 h.

5. The method according to claim 1, characterized in that: Before the curing step, the method further comprises: In the vacuum shaping step, the outer periphery of the test block blank (100) is wrapped with air-permeable felt and then placed in a vacuum bag to evacuate the bag.

6. The method according to claim 1, characterized in that: After the step of extracting the placeholder plate, the method further includes: The waterproof layer construction step comprises coating waterproof glue on the outer surface of the ultrasonic flaw detection test block (200).

7. The manufacturing method according to claim 1, characterized in that: The thickness of the design defect placeholder plate (2) is d, 0.5 mm ≤ d ≤ 3 mm; and / or the design size is the same as the size of the test piece.

8. The method according to claim 7, characterized in that: The design defect placeholder plate (2) has a plurality of rectangular comb teeth of different widths.

9. The manufacturing method according to claim 1, characterized in that: 5°≤a≤30°。 10. An ultrasonic flaw detection test block, characterized in that: The ultrasonic flaw detection test block is manufactured by the manufacturing method of any one of claims 1 to 9.

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