Carbon fiber yarn type image quality indicator for graphite heat exchange tube radiographic inspection and use method of carbon fiber yarn type image quality indicator

Abstract

The invention relates to the technical field of graphite heat exchange tube radiographic inspection, in particular to a carbon fiber yarn type image quality indicator for graphite heat exchange tube radiographic inspection and a using method thereof.The carbon fiber yarn type image quality indicator comprises a carbon fiber yarn type image quality indicator body, and an identification area is arranged in the carbon fiber yarn type image quality indicator body; a plastic film is arranged on the outer surface of the carbon fiber yarn type image quality indicator body, a first carbon fiber filament is installed in the carbon fiber yarn type image quality indicator body, and a second carbon fiber filament is installed in the identification area. According to the method, the problem that a large number of internal defects may be missed due to the fact that an aluminum image quality indicator is directly selected to judge the sensitivity of the graphite heat exchange tube detection process loosely at present is solved, and meanwhile, the method can be used for verifying the sensitivity of graphite tube radiographic inspection equipment and process; graphite pipe production enterprises are helped to master a reliable graphite heat exchange pipe internal detection mode, and production efficiency and quality are promoted to be improved.

Description

Technical Field

[0001] The invention relates to the technical field of graphite heat exchange tube ray detection, in particular to a carbon fiber wire-type image quality meter for graphite heat exchange tube ray detection and a use method thereof. Background Art

[0002] As the core heat transfer component of the shell-and-tube graphite heat exchanger, the production quality of the graphite tube is directly related to the performance stability and service life of the heat exchanger from the source. At present, the main test method for the performance of graphite tubes by manufacturers is mainly verification test, including sampling mechanical property test and pipe-by-pipe water pressure test. The former has certain uncertainty in the quality assurance of batch products, and the latter is based on manual visual observation, which not only wastes a lot of resources and time, but also has a certain risk of missed inspection. If efficient non-destructive testing projects are introduced in the production and inspection process of graphite tubes to achieve full coverage of internal defect detection of graphite tubes, it will help improve production efficiency and quality and reduce the waste of resources in subsequent unnecessary inspections;

[0003] In this regard, China's application announcement number: CN108731992A discloses a method for preparing a carbon fiber bundle test specimen, using an aqueous solution of a water-based epoxy resin and a water-based epoxy resin curing agent as an impregnation liquid, pre-soaking the carbon fiber bundle with a phosphate adhesion promoter before impregnation, and applying a certain tension to the carbon fiber bundle during the impregnation process, and obtaining a carbon fiber mechanical property test specimen after drying and curing. The present invention solves the disadvantage of using a large amount of acetone as a solvent in the traditional preparation process of carbon fiber bundle test specimens, and solves the problem of the difficulty of adhesion of the water-based epoxy resin aqueous solution as an impregnation liquid, and has the advantages of fast operation, simplicity, and non-toxicity and environmental protection.

[0004] In this regard, China Application Announcement No.: CN113205497B discloses a dual-wire image quality meter image processing method, device, equipment and medium, wherein the method includes: obtaining an image to be processed; determining candidate pixels corresponding to the grayscale minimum value from a row of pixels passing through all wire pairs; determining two target pixels corresponding to the identifiable wire pairs from the candidate pixels according to the grayscale value and / or position information of each candidate pixel; for each group of identifiable wire pairs, determining the grayscale maximum value from the grayscale values ​​of the pixels located between the two target pixels; determining the identifiable rate of each group of identifiable wire pairs according to the grayscale values ​​and grayscale maximum values ​​of the two target pixels corresponding to each group of identifiable wire pairs. At the same time, the wire pairs used to calculate the spatial resolution of the image to be processed are determined according to the identifiable rate, and the spatial resolution of the image to be processed is obtained. The present invention directly processes the image to be processed, reducing the amount of data processing during image analysis.

[0005] In this regard, China's application announcement number: CN105606633B, discloses an X-ray imaging system having a distributed X-ray source, a fixed grating module, an X-ray detector and a computer workstation, wherein the object to be detected is located between the distributed X-ray source and the fixed grating module, and the computer workstation is controlled to implement the following process: each light source of the distributed X-ray source is exposed in sequence to emit X-rays to the object to be detected; during each exposure, the X-ray detector receives the X-rays, and after a step exposure process and data acquisition of the distributed X-ray source, the light intensity of the X-rays at each pixel point on the X-ray detector is represented as a light intensity curve; the light intensity curve is compared with the light intensity curve in the absence of the object to be detected, and the pixel value of each pixel point is obtained from the change in the light intensity curve; and the image of the object to be detected is reconstructed according to the obtained pixel value.

[0006] In this regard, China's application announcement number: CN219104779U, discloses a transverse crack indicator for X-ray detection, in which a plurality of transverse crack indicator components are embedded inside a rectangular structure substrate, and the transverse crack indicator components are arranged equidistantly inside the substrate along the length direction of the substrate. The transverse crack indicator component includes an indicator and a marker, and one end of the marker is fixedly connected to the side of the indicator. The transverse crack indicator component can generate an image on the X-ray image. By observation, the identifiable indicator image farthest from the center of the indicator represents the maximum transverse crack offset of this X-ray detection, and the maximum single-exposure length and maximum transverse crack detection angle that meet the transverse crack detection can be obtained. The transverse crack detection capability of X-ray detection can be intuitively and efficiently evaluated, and can be used for X-ray detection process formulation and improving the transverse crack detection rate of X-ray detection.

[0007] Radiographic testing is an important nondestructive testing method for detecting internal defects. The indicators for evaluating image quality in traditional nondestructive testing and digital radiographic testing include sensitivity, clarity, blackness, signal-to-noise ratio, etc. Among them, sensitivity is used to evaluate the minimum size of defects that can be observed during testing and the difficulty of detecting small defects. It is related to the defect missed detection rate and directly affects the reliability and effectiveness of the radiographic testing process. The image quality meter is an important component for determining the relative sensitivity of radiographic testing. Its reliability directly leads to overly strict or loose judgments on product defects. There are three main types of image quality meters currently in widespread use: wire-type image quality meters, step-hole-type image quality meters, and flat-plate-type image quality meters. In addition, there are slot-type image quality meters and double-wire image quality meters. There are several main aspects to consider when selecting an image quality meter for radiographic testing. The first is the material of the image quality meter. Generally, the material with the same material as the object being tested or the same radiation absorption coefficient should be selected. The second is the placement and penetration thickness. According to "NB / T47013-2015 Nondestructive Testing of Pressure Equipment", the image quality meter is placed on the source side or the film side during testing. Different wire diameters or apertures of the image quality meter need to be identified for different penetration thicknesses.

[0008] From the perspective of graphite tube X-ray detection needs, there is currently no non-metallic image quality meter of suitable material and model, and new image quality meters are in urgent need of research. Summary of the invention

[0009] The object of the present invention is to provide a carbon fiber filament image quality meter for X-ray inspection of graphite heat exchange tubes and a method of using the same, so as to solve the problem that there is a certain uncertainty in the quality assurance of batch products proposed in the above-mentioned background technology. The latter is based on manual visual observation, which not only causes a large amount of resource and time waste, but also has a certain risk of missed inspection, and there is a problem that there is no non-metallic image quality meter compatible with the graphite tube when performing X-ray inspection.

[0010] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a carbon fiber filament type image quality meter for graphite heat exchange tube radiation detection, comprising a carbon fiber filament type image quality meter body, a marking area is arranged inside the carbon fiber filament type image quality meter body, a plastic film is arranged on the outer surface of the carbon fiber filament type image quality meter body, a first carbon fiber filament is installed inside the carbon fiber filament type image quality meter body, a second carbon fiber filament is installed inside the marking area, both ends of the first carbon fiber filament are fixed to the plastic film by heat sealing, the number of single filaments contained in a single bundle of the first carbon fiber filament and the second carbon fiber filament is divided into multiple specifications of 1-24K, the first carbon fiber filament is arranged in five groups, the interval between two adjacent groups of first carbon fiber filaments is 5mm, the length of the first carbon fiber filament is 30mm, and the thickness of the plastic film is 0.03mm;

[0011] A bonding film, wherein the bonding film is mounted on the left and right side surfaces of the carbon fiber filament image quality meter body, a fixing frame is mounted on the right side surface of the bonding film, a mounting plate is mounted on the inner side wall of the fixing frame, a rubber block is mounted on the top surface of the mounting plate, a leakage net is provided inside the mounting plate, two groups of the leakage nets are provided, a groove that matches the two groups of leakage nets is provided at the bottom end of the fixing frame, an extrusion block is mounted on the top surface of the rubber block, an adapting groove is provided inside the extrusion block, two groups of the adapting grooves are provided, an adapting block is provided inside the adapting groove, a bonding block is mounted on the outer surface of the adapting block, a connecting rod is mounted on the top surface of the adapting block, a pressing plate is mounted on the top surface of the connecting rod, a guide frame is mounted on the inner wall of the fixing frame, an elastic strip is mounted on the top surface of the fixing frame, the elastic strip is made of elastic material, and the lower surface of the elastic strip contacts the top surface of the pressing plate.

[0012] Preferably, the lower surface of the fitting block fits the top surface of the extrusion block, and the adapting groove and the adapting block fit each other.

[0013] Preferably, 1K means that a bundle contains about 1000 single filaments, and 24K means that a bundle contains about 24000 single filaments, and the specification of the single filaments is uniformly 6.9 μm.

[0014] Preferably, the first carbon fiber filaments and the second carbon fiber filaments are prepared by the following process: impregnating with epoxy resin and curing into filaments of a certain diameter:

[0015] S1. Using acetone as solvent, epoxy resin and triethylenetetramine according to the weight ratio of the leak: 1, a uniform carbon fiber impregnated glue solution was prepared;

[0016] S2. Cut a certain length of carbon fiber multifilament, soak it in glue for 2-4 minutes, remove excess glue from the multifilament soaked in glue, fix it on a constant tension wire rack, straighten and tighten the multifilament and dry it at room temperature, or fix the multifilament first and then soak it in glue;

[0017] S3. Place the wire rack in an oven for curing at a temperature of (120 ± 5) °C and a curing time of not less than 60 min;

[0018] S4. After curing, the carbon fiber wire diameter is cut into sections of 50 mm in length. The carbon fiber wire should be evenly impregnated with glue, smooth, straight, and free of defects, and the resin content should be controlled within the range of 35-50%.

[0019] Preferably, the compressive strength of the first carbon fiber filaments and the second carbon fiber filaments reaches 4900 MPa.

[0020] Preferably, through processes such as impregnation, curing, and stretching, the diameter of the filaments produced from 1-24K carbon fiber is in the range of 0.28-1.3 mm.

[0021] Preferably, the upper surfaces of the first carbon fiber filaments are in contact with the upper and lower surfaces of the plastic film respectively, and are fixed by heat pressing.

[0022] Preferably, the carbon fiber wire type image quality meter body is placed on the surface of the graphite heat exchange tube when in use, and the carbon fiber wire type image quality meter body has a stretching function, and the carbon fiber wire type image quality meter body is arc-shaped.

[0023] Preferably, the connecting rod and the guide frame are adapted to each other, and an adhesive is provided between the mounting plate and the extrusion block.

[0024] A method for using a carbon fiber wire-type image quality meter for ray detection of graphite heat exchange tubes:

[0025] S1. Set up X-ray digital automatic detection on the graphite tube production line to identify internal defects of the heat exchange tube. Select double-wall double-image vertical transillumination overlapping imaging for transillumination, and transillumination three times at intervals of 120° or 60°. The inspection tooling includes the function of fixed clamping and rotating angle at both ends, and can automatically complete functions such as one-time transillumination length advancement and 60° angle directional rotation through program settings;

[0026] S2. Use graphite step test blocks to make X-ray digital detection exposure curves for graphite materials, clarify the range of transillumination voltage and exposure that meet grayscale requirements under certain focal length conditions, select appropriate transillumination parameters based on transillumination wall thickness, focal length and other conditions, and place the carbon fiber wire-type image quality meter on the side of the radiation source, tightly fitting it horizontally on the heat exchange tube;

[0027] S3. Considering the influence of the penetration angle on the transverse defect detection rate, the penetration length is generally selected to be half of the penetration focal length. Considering that the specifications and penetration parameters of the entire tube (about 4-6m long) remain unchanged, when continuously collecting multiple images in the extension direction, it is only necessary to place the image quality meter at 1 / 8 of the focal length of one end of the graphite tube, and then conduct subsequent inspections. The recognition status of the image quality meter in the image is used as the sensitivity of the X-ray digital inspection of the entire graphite tube;

[0028] S4. According to the thread number of the identifiable image quality meter in the detection imaging or the number of identifiable roots of the equal-diameter image quality meter, determine whether the selected radiographic equipment and parameters meet the requirements of the considered technical level. Only after the sensitivity and other quality judgment factors are confirmed to be consistent, can the quality level of graphite radiographic inspection be further determined by manual or intelligent identification of defect type, cross-sectional size, and maximum depth, and then decide whether to transfer it to subsequent production inspection processes such as heat treatment and water pressure.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] 1. The carbon fiber filament type image quality meter for graphite heat exchange tube radiation detection and the use method thereof, by providing the carbon fiber filament type image quality meter body, the identification area, the plastic film, the first carbon fiber filament and the second carbon fiber filament, when in use, firstly after the graphite heat exchange tube is placed, the carbon fiber filament type image quality meter body is then placed as a whole on the outer surface of the graphite heat exchange tube, and the plastic film and the first carbon fiber filament both have good flexibility, so that within the range of the curvature radius of the conventional graphite tube, the carbon fiber filament type image quality meter body can be completely covered on the graphite heat exchange tube in a fully fitted manner, which solves the problem that when the traditional image quality meter detects a small-diameter tube placed on the source side, it does not fit tightly to the upper surface of the small-diameter tube, and the filaments are imaged in some positions Further geometric amplification, affecting the problem of sensitivity identification and judgment, in addition, changing the placement position of the metal image quality meter wire direction parallel to the tube axis of the metal small-diameter tube X-ray detection, attaching the carbon fiber wire along the circumference of the graphite tube, is more suitable for small-diameter tubes, avoiding the situation that when the width of the carbon fiber wire image quality meter body is greater than the tube diameter, the thickness of the wire diameter position does not conform to the actual situation, causing misjudgment of the sensitivity result. When using a universal carbon fiber image quality meter, pay attention to placing the side with a small wire diameter close to one end of the graphite tube to ensure higher sensitivity identification accuracy. The general metal image quality meter is covered with a plastic soft shell or liner, and the general double-layer thickness is 0.4-0.5mm, but because the radiation absorption coefficient of the plastic is similar to that of the metal Compared with metal wire, the gap is large. Under the X-ray transillumination process with higher tube voltage and larger exposure of metal materials, the plastic soft shell will not show images and affect the identification judgment. However, due to the relatively low atomic number and density of graphite materials, the applicable transillumination parameters are generally low. The traditional plastic soft shell will be imaged under this condition, affecting the verification of the detection process. Therefore, the image quality meter for graphite tube X-ray detection directly uses 0.03mm plastic film as the protective shell of carbon fiber filaments, and the overall use effect is good. Since the plastic film cannot support the heavier metal material identification, a single thicker second carbon fiber filament (such as 1000 filaments or 2000 filaments) is placed horizontally in the identification area to distinguish the graphite by the length difference. Specifications of equal-diameter image quality meters for tube X-ray detection, for example, 20mm represents an image quality meter made of 900-filament carbon fiber, connecting rod mm represents an image quality meter made of 800-filament carbon fiber, and so on... The transverse carbon fiber filament length of the universal image quality meter for graphite tube X-ray detection is 25mm. On this basis, a series of carbon fiber image quality meters that can be used for different wall thicknesses and different detection technology levels are formed. The material properties of the carbon fiber image quality meter are highly consistent with the graphite tube, which solves the problem that the current direct use of aluminum image quality meters to directly determine the sensitivity of the graphite heat exchange tube detection process is loose, which may cause a large number of internal defects to be missed, and at the same time solves the problem that the graphite material has no matching high-precision image quality meter.

[0031] 2. The carbon fiber wire-type image quality meter for X-ray detection of graphite heat exchange tubes and its use method, through the provided laminating film, fixing frame, mounting plate, rubber block, leakage screen, extrusion block, adapting groove, adapting block, laminating block, connecting rod, pressing plate, guide frame and elastic strip, when placing the carbon fiber wire-type image quality meter body, firstly, the carbon fiber wire-type image quality meter body is evenly laminated to the outer surface of the graphite heat exchange tube, and then the laminating film at both ends is pulled, and the lower surface of the laminating film is also laminated to the outer surface of the graphite heat exchange tube. At this time, the carbon fiber wire-type image quality meter body is in tension and tightly laminated to the outer surface of the graphite heat exchange tube, and the lower surface of the fixing frame is also laminated to the outer surface of the graphite heat exchange tube, and then the elastic strip is squeezed by hand, and the elastic strip is elastic, so that the lower surface of the elastic strip contacts the upper surface of the pressing plate, and then the pressing plate is pressed. It will move downward, and the connecting rod will also move downward. When the connecting rod moves downward, it will be limited by the guide frame, and then the connecting rod will drive the adapter block and the fitting block downward as a whole. First, the adapter block will enter the interior of the adapter groove. When the adapter block is fitted with the adapter groove, the lower surface of the fitting block will fit the top surface of the extrusion block, which will push the extrusion block downward. The rubber block has elasticity. At the same time, an adhesive is arranged between the mounting plate and the extrusion block. The adhesive is squeezed by the extrusion block, and then the adhesive will flow out from the mesh and the groove at the lower end of the fixed frame, so that the adhesive will flow to the surface of the graphite heat exchange tube through the outflowing adhesive, and be adhered and connected to the fixed frame. The overall connection stability is good, that is, the fitting stability between the carbon fiber filament image quality meter body and the graphite heat exchange tube is enhanced, which is convenient for subsequent detection operations. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a three-dimensional schematic diagram of the main structure of the carbon fiber filament image quality meter of the present invention;

[0033] Figure 2 It is a schematic diagram of the arc state of the main structure of the carbon fiber filament type image quality meter of the present invention;

[0034] Figure 3 It is a schematic diagram of the disassembled cross-section of the main structure of the carbon fiber filament type image quality meter of the present invention;

[0035] Figure 4 It is a schematic diagram of the disassembly of the fixed frame and the extrusion block structure of the present invention;

[0036] Figure 5 It is a schematic diagram of the disassembly of the fixed frame and the elastic strip structure of the present invention;

[0037] Figure 6 It is a schematic diagram of a universal image quality meter for graphite tube ray detection of the present invention;

[0038] Figure 7 This is a schematic diagram of an equal-diameter image quality meter specially used for graphite tube ray detection according to the present invention;

[0039] Figure 8 It is a schematic diagram of the placement of the image quality meter in the conventional small-diameter tube ray detection of the present invention;

[0040] Fig. 9 This is a schematic diagram of the placement of a carbon fiber image quality meter in a small-diameter tube ray detection of the present invention;

[0041] Fig.10 This is a schematic diagram of double-wall double-image vertical transillumination overlapping imaging of the present invention;

[0042] Fig.11 This is a schematic diagram of a digital ray inspection tool for heat exchange tubes of the present invention;

[0043] Fig.12 It is a schematic diagram of the digital ray detection exposure curve of the graphite material of the present invention;

[0044] Fig.13 It is a schematic diagram of digital imaging of a graphite heat exchange tube including imaging by an image quality meter according to the present invention;

[0045] Fig.14 It is a schematic diagram of the specifications of the graphite tube of the present invention and the required detection technology levels.

[0046] In the figure: 1. Carbon fiber filament image quality meter body; 2. Marking area; 3. Plastic film; 4. First carbon fiber filament; 5. Second carbon fiber filament; 6. Laminating film; 7. Fixing frame; 8. Mounting plate; 9. Rubber block; 10. Screen; 11. Extrusion block; 12. Adapter groove; 13. Adapter block; 14. Laminating block; 15. Connecting rod; 16. Pressing plate; 17. Guide frame; 18. Elastic strip. DETAILED DESCRIPTION

[0047] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0048] See also Figure 1-Figure 14 , an embodiment provided by the present invention:

[0049] The plastic film 3, the first carbon fiber filaments 4, the second carbon fiber filaments 5, the rubber block 9 and the elastic strip 18 used in the present application are all products that can be directly purchased on the market, and their principles and connection methods are all existing technologies well known to those skilled in the art, so they will not be repeated here.

[0050] A carbon fiber wire-type image quality meter for ray detection of graphite heat exchange tubes, comprising a carbon fiber wire-type image quality meter body 1, the entire carbon fiber wire-type image quality meter body 1 is flexible and can be fitted according to the diameter of the pipe, an identification area 2 is arranged inside the carbon fiber wire-type image quality meter body 1, a plastic film 3 is arranged on the outer surface of the carbon fiber wire-type image quality meter body 1, a first carbon fiber filament 4 is installed inside the carbon fiber wire-type image quality meter body 1, a second carbon fiber filament 5 is installed inside the identification area 2, both ends of the first carbon fiber filament 4 are fixed to the plastic film 3 by heat sealing, and the number of single filaments contained in a single bundle of the first carbon fiber filament 4 and the second carbon fiber filament 5 is divided into 1 -24K multiple specifications, the first carbon fiber filaments 4 are arranged in five groups, the interval between two adjacent groups of the first carbon fiber filaments 4 is 5mm, the length of the first carbon fiber filaments 4 is 30mm, the thickness of the plastic film 3 is 0.03mm, the graphite heat exchange tube is divided into two categories, one is a pressed graphite tube, which is made of graphite powder and resin mixed in a certain proportion, kneaded, pressed and heat treated, and the other is an impregnated graphite tube, which is processed by cutting, drilling, turning, impregnation with resin and bonding with graphite electrodes. Generally speaking, the raw materials of graphite heat exchange tubes are graphite and resin. The atomic numbers of carbon fiber and graphite are both 6, and the density of the former is about 1.8g / cm 3 , the latter has a density of 1.5-2.3g / cm 3 The carbon fiber filaments and graphite tubes are the same or similar in atomic number, density, process and radiation absorption coefficient. Unlike graphite, which is a brittle material with a tensile strength of only about 20MPa, the compressive strength of carbon fiber reaches 4900MPa and has excellent ductility. It is suitable as an image quality meter wire for radiographic inspection of graphite heat exchange tubes. The production method of the carbon fiber harness adopts a resin glue formula and curing process for the production of carbon fiber multifilament tensile test specimens in the current GB / T3362-2017.

[0051] A bonding film 6 is installed on the left and right side surfaces of the carbon fiber filament image quality meter body 1. A fixing frame 7 is installed on the right side surface of the bonding film 6. A mounting plate 8 is installed on the inner side wall of the fixing frame 7. A rubber block 9 is installed on the top surface of the mounting plate 8. A leakage net 10 is provided inside the mounting plate 8. Two groups of leakage nets 10 are provided. A groove that matches the two groups of leakage nets 10 is provided at the bottom end of the fixing frame 7. An extrusion block 11 is installed on the top surface of the rubber block 9. An adapting groove 12 is provided inside the extrusion block 11. Two groups of adapting grooves 12 are provided. An adapting block 13 is provided inside the adapting groove 12. A bonding block 14 is installed on the outer surface of the adapting block 13. A connecting rod 15 is installed on the top surface of the adapting block 13. The connecting rod 1 5 is installed with a pressing plate 16 on the top surface, a guide frame 17 is installed on the outer surface of the connecting rod 15, and the guide frame 17 is installed on the inner wall of the fixed frame 7. An elastic strip 18 is installed on the top surface of the fixed frame 7. The elastic strip 18 is made of elastic material, and the lower surface of the elastic strip 18 contacts the top surface of the pressing plate 16. The lower surface of the fitting block 14 fits the top surface of the extrusion block 11. The adapting groove 12 and the adapting block 13 are adapted to each other. 1K means that a bundle contains about 1000 single filaments, and 24K means that it contains about 24000 single filaments. The single filament specification is unified to 6.9μm. After the graphite heat exchange tube is placed, the carbon fiber filament type image quality meter body 1 is placed as a whole on the outer surface of the graphite heat exchange tube, and the plastic film 3 and The first carbon fiber filaments 4 all have good flexibility, which enables the carbon fiber wire-type image quality meter body 1 to be completely covered on the graphite heat exchange tube within the curvature radius of the conventional graphite tube, thereby solving the problem that when the traditional image quality meter detects a small-diameter tube and places it on the source side, it does not fit tightly to the upper surface of the small-diameter tube, and the imaging of the filaments at some positions is further geometrically amplified, which affects the sensitivity identification and judgment. In addition, the placement position of the metal image quality meter wire direction parallel to the axial direction of the tube is changed for the metal small-diameter tube X-ray detection, and the carbon fiber wire is attached along the circumference of the graphite tube, which is more suitable for small-diameter tubes, and avoids the situation that when the width of the carbon fiber wire-type image quality meter body 1 is greater than the tube diameter, the thickness of the irradiation at the wire diameter position does not conform to the actual situation, causing sensitivity When selecting a universal carbon fiber image quality meter, pay attention to placing the side with a small wire diameter close to the end of the graphite tube to ensure higher sensitivity recognition accuracy. The envelope of a general metal image quality meter is a plastic soft shell or liner, and the general double-layer thickness is 0.4-0.5mm. However, due to the large difference in the radiation absorption coefficient of plastic compared with that of metal wire, under the radiation transillumination process of metal materials with higher tube voltage and larger exposure, the plastic soft shell will not show an image and affect the recognition judgment. However, due to the relatively low atomic number and density of graphite materials, the applicable transillumination parameters are generally low. The traditional plastic soft shell will form an image under this condition, affecting the verification of the detection process. Therefore, the graphite tube radiation detection image quality meter directly uses 0.The 0.3mm plastic film 3 is used as a protective shell for the carbon fiber filaments, and the overall use effect is good. Since the plastic film 3 cannot support the heavier metal material identification, a single thicker second carbon fiber filament 5 (for example, 1000 filaments or 2000 filaments) is placed horizontally in the identification area 2, and the length difference is used to distinguish the specifications of the equal-diameter image quality meter for graphite tube X-ray detection. For example, 20mm represents an image quality meter made of 900 filaments of carbon fiber, and the connecting rod 15mm represents an image quality meter made of 800 filaments of carbon fiber, and so on... The horizontal carbon fiber filament length of the universal image quality meter for graphite tube X-ray detection is 25mm. On this basis, a series of carbon fiber image quality meters that can be used for different wall thicknesses and different detection technology levels are formed. The material characteristics of the carbon fiber image quality meter are highly consistent with the graphite tube, which solves the problem that the current direct use of aluminum image quality meters to directly determine the sensitivity of the graphite heat exchange tube detection process is loose, which may cause a large number of internal defects to be missed. .

[0052] The preparation process of the first carbon fiber filament 4 and the second carbon fiber filament 5 is as follows: impregnating epoxy resin and curing into filaments of a certain diameter:

[0053] S1. Using acetone as solvent, epoxy resin E-44 or E-51 and triethylenetetramine in a weight ratio of 10:1, a uniform carbon fiber impregnation glue solution was prepared;

[0054] S2. Cut a certain length of carbon fiber multifilament, soak it in glue for 2-4 minutes, remove excess glue from the multifilament soaked in glue, fix it on a constant tension wire rack, straighten and tighten the multifilament and dry it at room temperature, or fix the multifilament first and then soak it in glue;

[0055] S3. Place the wire rack in an oven for curing at a temperature of (120 ± 5) °C and a curing time of not less than 60 min;

[0056] S4. After curing, the carbon fiber wire diameter is cut into sections of 50 mm in length. The carbon fiber wire should be evenly impregnated with glue, smooth, straight, and free of defects, and the resin content should be controlled within the range of 35-50%.

[0057] The compressive strength of the first carbon fiber filament 4 and the second carbon fiber filament 5 reaches 4900MPa. Through the processes of impregnation, curing, stretching, etc., the diameter range of the filament made of 1-24K carbon fiber is 0.28-1.3mm. The upper surface of the first carbon fiber filament 4 is in contact with the upper and lower surfaces of the plastic film 3 respectively, and is fixed by hot pressing. The carbon fiber wire type image quality meter body 1 is placed on the surface of the graphite heat exchange tube when in use, and the carbon fiber wire type image quality meter body 1 has a stretching function. The carbon fiber wire type image quality meter body 1 is arc-shaped. The connecting rod 15 and the guide frame 17 are adapted to each other, and an adhesive is provided between the mounting plate 8 and the extrusion block 11. When placing the carbon fiber wire type image quality meter body 1, the carbon fiber wire type image quality meter body 1 is first evenly attached to the outer surface of the graphite heat exchange tube, and then the bonding film 6 at both ends is pulled, and the lower surface of the bonding film 6 is also attached to the outer surface of the graphite heat exchange tube. At this time, the carbon fiber wire type image quality meter body 1 is in tension and tightly attached to the outer surface of the graphite heat exchange tube, and the lower surface of the fixing frame 7 is also attached to the outer surface of the graphite heat exchange tube, and then Then, the elastic strip 18 is squeezed by hand, and the elastic strip 18 is elastic, so that the lower surface of the elastic strip 18 will contact the upper surface of the pressing plate 16, and then the pressing plate 16 will move downward, and the connecting rod 15 will also move downward. When the connecting rod 15 moves downward, it is limited by the guide frame 17, and then the connecting rod 15 will drive the adapter block 13 and the fitting block 14 to move downward as a whole. First, the adapter block 13 will enter the inside of the adapter groove 12. When the adapter block 13 is adapted to the adapter groove 12, the lower surface of the fitting block 14 will fit the extrusion block The top surface of 11 will push the extrusion block 11 downward, and the rubber block 9 has elasticity. At the same time, an adhesive is arranged between the mounting plate 8 and the extrusion block 11. The adhesive is squeezed by the extrusion block 11, and then the adhesive flows out from the leakage net 10 and the groove at the lower end of the fixed frame 7, so that the outflowing adhesive will flow to the surface of the graphite heat exchange tube and be adhered and connected to the fixed frame 7. The overall connection stability is good, that is, the fitting stability between the carbon fiber wire image quality meter body 1 and the graphite heat exchange tube is enhanced, which is convenient for subsequent detection operations.

[0058] A method for using a carbon fiber wire-type image quality meter for ray inspection of graphite heat exchange tubes:

[0059] S1. Set up X-ray digital automatic detection on the graphite tube production line to identify internal defects of the heat exchange tube. Select double-wall double-image vertical transillumination overlapping imaging for transillumination, and transillumination three times at intervals of 120° or 60°. The inspection tooling includes the function of fixed clamping and rotating angle at both ends, and can automatically complete functions such as one-time transillumination length advancement and 60° angle directional rotation through program settings;

[0060] S2. Use graphite step test blocks to make X-ray digital detection exposure curves for graphite materials, clarify the range of transillumination voltage and exposure that meet grayscale requirements under certain focal length conditions, select appropriate transillumination parameters based on transillumination wall thickness, focal length and other conditions, and place the carbon fiber wire-type image quality meter on the side of the radiation source, tightly fitting it horizontally on the heat exchange tube;

[0061] S3. Considering the influence of the penetration angle on the transverse defect detection rate, the penetration length is generally selected to be half of the penetration focal length. Considering that the specifications and penetration parameters of the entire tube (about 4-6m long) remain unchanged, when continuously collecting multiple images in the extension direction, it is only necessary to place the image quality meter at 1 / 8 of the focal length of one end of the graphite tube, and then conduct subsequent inspections. The recognition status of the image quality meter in the image is used as the sensitivity of the X-ray digital inspection of the entire graphite tube;

[0062] S4. According to the thread number of the identifiable image quality meter in the detection imaging or the number of identifiable roots of the equal-diameter image quality meter, determine whether the selected radiographic equipment and parameters meet the requirements of the considered technical level. Only after the sensitivity and other quality judgment factors are confirmed to be consistent, can the quality level of graphite radiographic inspection be further determined by manual or intelligent identification of defect type, cross-sectional size, and maximum depth, and then decide whether to transfer it to subsequent production inspection processes such as heat treatment and water pressure.

[0063] Graphite heat exchange tubes on the market are mainly divided into Equal specifications, belonging to the small diameter tube with an outer diameter less than 100mm, can be used for radiation detection according to the double-wall double-shadow vertical transillumination process. For sensitivity identification, ordinary image quality meter or special equal-diameter wire type image quality meter can be used. Corresponding to different transillumination thickness and technical level requirements, the wire diameter range of the image quality meter to be identified is 0.16-0.25mm. Order 500, 600, 700, 800, 900, 1000 wire carbon fiber multifilaments to produce six different diameter specifications of carbon fiber filaments;

[0064] Embodiment 1: Six carbon fiber filaments of different diameters are selected, with a length L of 30 mm and an interval S of 5 mm between adjacent filaments. A universal image quality meter for X-ray inspection of graphite tubes suitable for all specifications of heat exchange tubes and all technical levels is manufactured. The requirements for identifying filaments are expressed in the number of carbon fiber filaments as shown in the following table. The length of the filament number exceeding 1 cm is considered to be identifiable. The transillumination equipment and process are verified by sensitivity. When selecting a universal carbon fiber image quality meter, pay attention to placing the side with a small filament diameter close to one end of the graphite tube to ensure higher sensitivity identification accuracy.

[0065] Embodiment 2: five carbon fiber filaments of the same diameter are used, with a length L of 30 mm and an interval S between adjacent filaments of 5 mm, to produce an equal-diameter image quality meter for graphite tube X-ray detection. According to the identification requirements in the above table, five specifications and models of carbon fiber equal-diameter filament image quality meters of 500 filaments, 600 filaments, 700 filaments, 800 filaments and 900 filaments are produced. In the specific detection, a special equal-diameter image quality meter is selected according to different graphite tube specifications and required detection technology levels. If two of them can be identified, it is regarded that the radiography equipment and process have passed the sensitivity verification.

[0066] Through the first embodiment, a universal image quality meter for graphite tube radiographic inspection suitable for all specifications of heat exchange tubes and all technical level requirements can be manufactured, and the second embodiment can manufacture an equal-diameter image quality meter specifically for graphite tube radiographic inspection, and both of the above-mentioned image quality meters can be fitted and installed on the outer surface of the graphite heat exchange tube. This type of image quality meter can also be used for radiographic inspection sensitivity determination of other non-metallic materials similar to graphite, such as silicon carbide, carbon fiber composite materials, carbon fiber reinforced plastics, etc., to improve the accuracy of radiographic inspection of internal defects and reduce the missed detection rate. It is mainly used for sensitivity verification of graphite tube radiographic inspection equipment and processes, helping graphite tube manufacturers to master reliable internal inspection methods for graphite heat exchange tubes and promote production efficiency and quality improvement.

[0067] Working principle: When in use, first place the graphite heat exchange tube, and then place the carbon fiber filament type image quality meter body 1 as a whole on the outer surface of the graphite heat exchange tube, and the plastic film 3 and the first carbon fiber filament 4 have good flexibility, so that within the curvature radius of the conventional graphite tube, the carbon fiber filament type image quality meter body 1 can be wrapped on the graphite heat exchange tube in a completely fitting manner, by pulling the bonding film 6 at both ends, and the lower surface of the bonding film 6 will also be bonded to the outer surface of the graphite heat exchange tube. At this time, the carbon fiber filament type image quality meter body 1 is in a state of tension and tightly fitting the outer surface of the graphite heat exchange tube, and the lower surface of the fixing frame 7 is also in contact with the outer surface of the graphite heat exchange tube, and then the elastic strip 18 is squeezed by hand, and the elastic strip 18 is elastic, so that the lower surface of the elastic strip 18 It will contact the upper surface of the pressing plate 16, and then the pressing plate 16 will move downward. At this time, the connecting rod 15 will also move downward. When the connecting rod 15 moves downward, it will be limited by the guide frame 17. Then the connecting rod 15 will drive the adapter block 13 and the fitting block 14 downward as a whole. First, the adapter block 13 will enter the interior of the adapter groove 12. When the adapter block 13 is adapted to the adapter groove 12, the lower surface of the fitting block 14 will fit the top surface of the extrusion block 11, which will push the extrusion block 11 downward. The rubber block 9 has elasticity. At the same time, an adhesive is provided between the mounting plate 8 and the extrusion block 11. The adhesive is squeezed by the extrusion block 11, and then the adhesive will flow out from the groove at the lower end of the leakage net 10 and the fixing frame 7, so that the adhesive will flow to the graphite heat exchange tube. The surface of the graphite tube is adhered and connected with the fixed frame 7. An automatic X-ray digital inspection is set on the graphite tube production line to identify the internal defects of the heat exchange tube. The double-wall double-shadow vertical transillumination overlapping imaging is selected for the transillumination mode. The transillumination is performed three times at an interval of 120° or 60°. The inspection tooling includes a fixed clamping rotation angle function at both ends. The functions of one transillumination length advancement and 60° angle directional rotation can be automatically completed through program settings. The X-ray digital inspection exposure curve of the graphite material is made using the graphite step test block. The transillumination voltage and exposure range that meet the grayscale requirements under certain focal length conditions are clearly defined. According to the transillumination wall thickness, focal length and other conditions, the appropriate transillumination parameters are selected. The carbon fiber filament image quality meter is placed on the side of the ray source and closely fits the heat exchange tube horizontally. Considering the effect of the transillumination angle on the horizontal The impact of defect detection rate, the length of one exposure is generally selected to be half of the focal length of the exposure. Considering that the specifications and exposure parameters of the whole tube are about 4-6m long and remain unchanged, when continuously collecting multiple images in the extension direction, it is only necessary to place the image quality meter at 1 / 8 of the focal length of one end of the graphite tube, and then conduct subsequent inspections. The recognition of the image quality meter in the image is used as the sensitivity of the X-ray digital detection of the whole graphite tube. According to the number of threads that can be identified by the image quality meter in the detection imaging or the number of threads that can be identified by the image quality meter of equal diameter, it is judged whether the selected exposure equipment and parameters meet the requirements of the technical level. Only on the basis of confirming the consistency of sensitivity and other quality judgment factors, can the quality level of graphite ray detection be further determined by manual or intelligent recognition of defect type, cross-sectional size and maximum depth.Then decide whether to transfer it to the subsequent production inspection process such as heat treatment and water pressure. The above is the working principle of the present invention.

[0068] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any ordinary technician in the industry can smoothly implement the present invention as shown in the drawings and described above. However, any equivalent changes, modifications and evolutions made by technicians familiar with the profession without departing from the scope of the technical solution of the present invention using the technical content disclosed above are all equivalent embodiments of the present invention. At the same time, any equivalent changes, modifications and evolutions made to the above embodiments based on the essential technology of the present invention are still within the protection scope of the technical solution of the present invention.

Claims

1. A carbon fiber wire-type image quality meter for graphite heat exchange tube radiographic inspection, comprising a carbon fiber wire-type image quality meter body (1), characterized in that: The carbon fiber filament image quality meter body (1) is provided with an identification area (2) inside, the outer surface of the carbon fiber filament image quality meter body (1) is provided with a plastic film (3), the carbon fiber filament image quality meter body (1) is provided with a first carbon fiber filament (4) inside, the identification area (2) is provided with a second carbon fiber filament (5), the two ends of the first carbon fiber filament (4) and the plastic film (3) are fixed by heat sealing, the number of single filaments contained in a single bundle of the first carbon fiber filament (4) and the second carbon fiber filament (5) is divided into multiple specifications of 1-24K, the first carbon fiber filament (4) is provided with five groups, the interval between two adjacent groups of the first carbon fiber filament (4) is 5mm, the length of the first carbon fiber filament (4) is 30mm, and the thickness of the plastic film (3) is 0.03mm; A bonding film (6), wherein the bonding film (6) is mounted on the left and right side surfaces of a carbon fiber filament-type image quality meter body (1), a fixing frame (7) is mounted on the right side surface of the bonding film (6), a mounting plate (8) is mounted on the inner side wall of the fixing frame (7), a rubber block (9) is mounted on the top surface of the mounting plate (8), a leakage net (10) is provided inside the mounting plate (8), two groups of the leakage net (10) are provided, a groove mutually adapted to the two groups of leakage nets (10) is provided at the bottom end of the fixing frame (7), an extrusion block (11) is mounted on the top surface of the rubber block (9), an adaption groove (12) is provided inside the extrusion block (11), and the The adapting groove (12) is provided with two groups, an adapting block (13) is provided inside the adapting groove (12), a fitting block (14) is installed on the outer surface of the adapting block (13), a connecting rod (15) is installed on the top surface of the adapting block (13), a pressing plate (16) is installed on the top surface of the connecting rod (15), a guide frame (17) is installed on the outer surface of the connecting rod (15), the guide frame (17) is installed on the inner wall of the fixing frame (7), an elastic strip (18) is installed on the top surface of the fixing frame (7), the elastic strip (18) is made of elastic material, and the lower surface of the elastic strip (18) contacts the top surface of the pressing plate (16).

2. The carbon fiber wire-type image quality meter for radiographic inspection of graphite heat exchange tubes according to claim 1, characterized in that: The lower surface of the fitting block (14) fits the top surface of the extrusion block (11), and the adapting groove (12) and the adapting block (13) fit each other.

3. The carbon fiber wire-type image quality meter for radiographic inspection of graphite heat exchange tubes according to claim 1, characterized in that: 1K means that a bundle contains about 1000 single filaments, and 24K means that it contains about 24000 single filaments. The specification of single filaments is uniformly 6.9μm.

4. The carbon fiber wire-type image quality meter for radiographic inspection of graphite heat exchange tubes according to claim 1, characterized in that: The preparation process of the first carbon fiber filaments (4) and the second carbon fiber filaments (5) is as follows: impregnating with epoxy resin and curing into filaments with a certain diameter: S1. Using acetone as solvent, epoxy resin (E-44 or E-51) and triethylenetetramine in a weight ratio of 10:1, a uniform carbon fiber impregnation glue solution was prepared; S2. Cut a certain length of carbon fiber multifilament, soak it in glue for 2-4 minutes, remove excess glue from the multifilament soaked in glue, fix it on a constant tension wire rack, straighten and tighten the multifilament and dry it at room temperature, or fix the multifilament first and then soak it in glue; S3. Place the wire rack in an oven for curing at a temperature of (120 ± 5) °C and a curing time of not less than 60 min; S4. After curing, the carbon fiber wire diameter is cut into sections of 50 mm in length. The carbon fiber wire should be evenly impregnated with glue, smooth, straight, and free of defects, and the resin content should be controlled within the range of 35-50%.

5. The carbon fiber wire-type image quality meter for radiographic inspection of graphite heat exchange tubes according to claim 1, characterized in that: The compressive strength of the first carbon fiber filaments (4) and the second carbon fiber filaments (5) reaches 4900 MPa.

6. The carbon fiber wire-type image quality meter for radiographic inspection of graphite heat exchange tubes according to claim 4, characterized in that: Through processes such as impregnation, curing, and stretching, the diameter of filaments produced from 1-24K carbon fiber ranges from 0.28 to 1.3 mm.

7. The carbon fiber wire-type image quality meter for radiographic inspection of graphite heat exchange tubes according to claim 1, characterized in that: The upper surfaces of the first carbon fiber filaments (4) are in contact with the upper and lower surfaces of the plastic film (3) respectively, and are fixed by heat pressing.

8. The carbon fiber wire-type image quality meter for radiographic inspection of graphite heat exchange tubes according to claim 1, characterized in that: The carbon fiber wire-type image quality meter body (1) is placed on the surface of a graphite heat exchange tube when in use, and the carbon fiber wire-type image quality meter body (1) has a stretching function. The carbon fiber wire-type image quality meter body (1) is in an arc shape.

9. The carbon fiber wire-type image quality meter for radiographic inspection of graphite heat exchange tubes according to claim 1, characterized in that: The connecting rod (15) and the guide frame (17) are adapted to each other, and an adhesive is provided between the mounting plate (8) and the extrusion block (11).

10. The method for using the carbon fiber wire-type image quality meter for radiographic inspection of graphite heat exchange tubes according to claims 1-9, characterized in that: S1. Set up X-ray digital automatic detection on the graphite tube production line to identify internal defects of the heat exchange tube. Select double-wall double-image vertical transillumination overlapping imaging for transillumination, and transillumination three times at intervals of 120° or 60°. The inspection tooling includes the function of fixed clamping and rotating angle at both ends, and can automatically complete functions such as one-time transillumination length advancement and 60° angle directional rotation through program settings; S2. Use graphite step test blocks to make X-ray digital detection exposure curves for graphite materials, clarify the range of transillumination voltage and exposure that meet grayscale requirements under certain focal length conditions, select appropriate transillumination parameters based on transillumination wall thickness, focal length and other conditions, and place the carbon fiber wire-type image quality meter on the side of the radiation source, tightly fitting it horizontally on the heat exchange tube; S3. Considering the influence of the penetration angle on the transverse defect detection rate, the penetration length is generally selected to be half of the penetration focal length. Considering that the specifications and penetration parameters of the entire tube (about 4-6m long) remain unchanged, when continuously collecting multiple images in the extension direction, it is only necessary to place the image quality meter at 1 / 8 of the focal length of one end of the graphite tube, and then conduct subsequent inspections. The recognition status of the image quality meter in the image is used as the sensitivity of the X-ray digital inspection of the entire graphite tube; S4. According to the thread number of the identifiable image quality meter in the detection imaging or the number of identifiable roots of the equal-diameter image quality meter, determine whether the selected radiographic equipment and parameters meet the requirements of the considered technical level. Only after the sensitivity and other quality judgment factors are confirmed to be consistent, can the quality level of graphite radiographic inspection be further determined by manual or intelligent identification of defect type, cross-sectional size, and maximum depth, and then decide whether to transfer it to subsequent production inspection processes such as heat treatment and water pressure.

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