Large-thickness electron beam weld defect repair welding spot X-ray positioning method

Abstract

The invention provides a large-thickness electron beam weld defect repair welding spot X-ray positioning method which comprises the following steps: S1, adopting vertical transillumination for the first time to find defects; s2, selecting a heavy metal marker and arranging; s3, preliminarily positioning the relative position of the marker and the defect; s4, performing primary iterative positioning; s5, iterating for multiple times until the relative positions of the positioning marker and the defect are adjusted; s6, carrying out oblique incidence and transillumination arrangement; s7, picking off the film; s8, washing the film; s9, the position of a repair welding spot and the repair welding depth are measured and calculated; and S10, ending the detection. According to the X-ray positioning method for the repair welding spot of the large-thickness electron beam welding seam defect, a heavy metal marker selection method and an oblique incident ray defect positioning method are arranged, so that rapid and accurate positioning of repair welding of the large-thickness electron beam welding seam defect is realized.

Description

Technical Field

[0001] The invention belongs to the technical field of material welding, and in particular relates to an X-ray positioning method for defective welding points of a thick electron beam weld. Background Art

[0002] A launch vehicle product uses two blocks with an area of ​​about 30m 2 , plates with a thickness of 30 to 80 mm are welded into blanks, and then spin-formed. The blanks are relatively thick and require high welding quality, so electron beam welding is used. Electron beam welding will form defects such as pores, lack of fusion, lack of penetration, and cracks. According to the requirements of GJB1718, electron beam welds need to be inspected for internal quality using X-rays. When the above defects are found, the welds need to be repaired to eliminate the defects and ensure the performance of the welds. When repairing electron beam welds, accurate repair positioning and reasonable welding parameters are the key factors for the success of repair welding. It is necessary to determine the repair welding position and adjust the welding parameters according to the position of the defect in the depth direction. Therefore, the position of the defect in the thickness direction becomes the key to the success of the repair welding. Conventional X-ray detection technology is that when X-rays pass through an object, the defective parts (such as pores, inclusions, cracks, etc.) in the object have different absorption capacities for X-rays than the matrix, resulting in differences in the intensity of the transmitted X-rays between the defective parts and the matrix. The X-rays that pass through the product will be received by the film, and the film will record the X-ray intensity that passes through the product at different positions. After being washed in a darkroom, the positions with high X-ray intensity will have a higher degree of blackness on the film, and vice versa, thus forming a film with a projection image of the defect, which does not contain the position information of the defect in the depth direction. Therefore, conventional X-ray detection technology is difficult to determine the position of the defect in the thickness direction of the weld. The present invention belongs to the technical field of electron beam weld positioning and repair welding position based on X-ray detection. The existing X-ray detection technology process is as follows: Figure 1 . The specific method is: (1) stick the film to the area to be irradiated, and place lead type labels and image quality meters, etc.; (2) adjust the focal length so that the central beam of rays is vertically incident on the center of the area to be irradiated; (3) start the X-ray machine and adjust the detection parameters according to the product thickness and focal length; (4) start the high voltage, generate X-rays, and start irradiation. After the irradiation is completed, turn off the high voltage; (5) remove the irradiated film; (6) process the film in a darkroom; (7) evaluate the film with the internal quality information of the product; (8) the detection is completed. The existing technology has the following disadvantages when detecting thick electron beam welds: it is impossible to locate the position of the defect in the thickness direction, so it is impossible to determine the repair welding position and select the repair welding parameters. It is urgent to develop a detection method that can locate the depth of the defect. Summary of the invention

[0003] In view of this, the present invention aims to propose an X-ray positioning method for defective repair welding points of thick electron beam welds, so as to solve the problem that the repair welding position cannot be determined and the repair welding parameters cannot be selected when detecting thick electron beam welds.

[0004] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0005] A method for X-ray positioning of defective welding points of thick electron beam welds, characterized in that it comprises the following steps:

[0006] S1. Vertical transillumination was used for the first time to find defects;

[0007] S2. Marker arrangement, where the size and material of heavy metal markers are determined by the following methods:

[0008] First, a cylindrical marker is selected; further, under the premise of ensuring clear images, the diameter of the marker is selected according to the size of the defect to be detected and the thickness of the base material; further, a steel cylindrical marker is selected for aluminum alloy materials; a copper cylindrical marker is selected for steel materials; further, according to the transillumination thickness and the diameter of the heavy metal marker, the following formula exists:

[0009]

[0010] in:

[0011] a: Projection length of the defect on the film;

[0012] b: The distance from the image of the upper marker on the film to the measurement origin;

[0013] c: The length of the defect from the measurement origin;

[0014] d: diameter of heavy metal marker;

[0015] F: focal length;

[0016] T: Transillumination thickness, approximately equal to the thickness of the base material;

[0017] S3. Preliminary positioning of the relative position between the marker and the defect;

[0018] S4, one iteration positioning;

[0019] S5, iterating multiple times until the relative position of the positioning marker and the defect is adjusted;

[0020] S6, oblique transillumination arrangement;

[0021] S7, take off the film;

[0022] S8, developing the film;

[0023] S9, measuring and calculating the position of the repair welding point and the repair welding depth;

[0024] S10: Detection ends.

[0025] Further, according to the X-ray positioning method for defective repair welding points of thick electron beam welds, it is characterized in that: S1, the weld is firstly illuminated by using the X-ray vertical incidence positioning method to find defects, and the specific method is as follows:

[0026] Vertical incidence method Figure 3 , the radiation source and the film are separated on both sides of the object to be inspected, the film is close to the weld, the distance between the radiation source and the surface of the object to be inspected is not less than 800mm, the X-ray beam is emitted from the radiation source, vertically incident on the surface of the object to be inspected, and passes through the object to be inspected to reach the film, forming a film with defect information, so as to preliminarily determine the defect location;

[0027] Further, according to the X-ray positioning method for a defective repair welding point of a thick electron beam weld, it is characterized in that: the method for preliminary positioning the relative position of the marker and the defect in S3 is: according to the position of the defect in S1, the upper and lower heavy metal markers are placed on the upper and lower sides of the defect, and then the marker and the defect position are verified by radiation. When the radiation is transilluminated, a plumb calibration beam is used to vertically impinge on the weld surface (such as Figure 3 ).

[0028] Further, according to the X-ray positioning method for defective repair welding points of thick electron beam welds, it is characterized in that the method of one iteration positioning in S4 is:

[0029] According to the preliminary transillumination results, adjust the positions of the upper and lower markers so that they overlap in the horizontal direction. The first iteration is completed through the above operations so that the distance between the upper and lower marker projections and the defect projection is controlled within 5 mm.

[0030] Further, according to the X-ray positioning method for defective repair welding points of thick electron beam welds, it is characterized in that: the specific method of performing multiple iterations in S5 until the relative position of the positioning marker and the defect is adjusted is:

[0031] X-rays are vertically incident on the weld surface for transillumination (such as Figure 3 );

[0032] According to the transillumination result after the first iteration, the positions of the upper and lower markers are adjusted again so that the projections of the upper and lower markers and the defects on the horizontal plane reach a higher degree of overlap than that of the first iteration. The second iteration is completed through the above operation;

[0033] Again, X-rays are vertically incident on the weld surface for transillumination (such as Figure 3 );

[0034] If there is still a deviation in the horizontal projections of the three after the second iteration, one or more iterations are performed until the deviation of the three projection centers is less than 0.2 mm (e.g. Figure 4 Right picture and Figure 5 );

[0035] Further, according to the X-ray positioning method for defective repair welding points of a thick electron beam weld, it is characterized in that: the specific method of the oblique transillumination arrangement in S6 is: the X-ray machine is moved away from the weld by 1000-1200mm, the X-ray beam is obliquely incident on the defect and the marker, and the height of the X-ray machine head is 1000-1200mm away from the upper surface of the object to be tested, so that the direction of the ray forms an observable acute angle with the upper surface of the object to be tested (such as Figure 6 );

[0036] Furthermore, according to the described X-ray positioning method for defective repair welding points of thick electron beam welds, it is characterized in that the observable acute angle of the oblique incidence of the ray beam is 45°.

[0037] Further, according to the X-ray positioning method for defective repair welding points of thick electron beam welds, it is characterized in that the method for measuring and calculating the position and depth of the repair welding points in S9 is:

[0038] In the film image, the distance between the upper marker and the defect is defined as X, the distance between the lower marker and the defect is defined as Y, the defect diameter is defined as Z, and the thickness of the weld base material to be tested is defined as R; according to the geometric relationship, it is calculated that the defect is X' away from the upper surface of the weld base material to be tested, and Y' away from its lower surface. The method for determining the repair welding point is: after the final iteration is completed, the upper and lower marker positions are determined, and the marker position closer to the defect is selected as the repair welding point; when repairing welding, all defects should be eliminated, so the repair welding depth should be greater than the distance between the defect and the upper surface + the defect diameter. X-ray detection finds that the defect has been eliminated and the product is qualified.

[0039] Compared with the prior art, the X-ray positioning method for defective repair welding points of thick electron beam welds described in the present invention has the following advantages:

[0040] (1) The X-ray positioning method for defective repair welding points of thick electron beam welds, the heavy metal marker selection method and the oblique incident ray defect positioning method provided by the present invention realize rapid and accurate positioning of defective repair welding of thick electron beam welds.

[0041] (2) The X-ray positioning method for defective repair welding points of thick electron beam welds described in the present invention effectively solves the problem of being unable to locate the position of defects in the thickness direction, determine the repair welding position and select the repair welding parameters when detecting thick electron beam welds.

[0042] (3) The X-ray positioning method for defective repair welding points of thick electron beam welds described in the present invention, wherein the method for selecting heavy metal markers is limited by a scientific formula, which is derived and summarized by the applicant based on the basic principles of detection and a large amount of practical operation experience, and can effectively improve the accuracy of determining the repair welding points.

[0043] (4) The X-ray positioning method for defective repair welding points of thick electron beam welds described in the present invention is suitable for positioning defects in electron beam repair welding with a thickness of more than 30 mm. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0045] Figure 1 This is a flow chart of the prior art detection process described in an embodiment of the present invention;

[0046] Figure 2 This is a process flow chart of the X-ray positioning method for defective repair welding points of thick electron beam welds according to an embodiment of the present invention;

[0047] Figure 3 A schematic diagram of the calibration between the metal marker and the defect position according to an embodiment of the present invention;

[0048] Figure 4 A schematic diagram of the relationship between the metal marker and the defect position after multiple iterations according to an embodiment of the present invention;

[0049] Figure 5 This is a schematic diagram of the marker and defect position image according to an embodiment of the present invention;

[0050] Figure 6 Schematic diagram of the principle of the heavy metal marker X-ray positioning method according to an embodiment of the present invention;

[0051] Figure 7 This is a schematic diagram of the positions of the metal marker and the defective film after oblique incidence according to an embodiment of the present invention.

[0052] Description of reference numerals: DETAILED DESCRIPTION

[0053] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0054] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and the like are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", and the like may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0055] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0056] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0057] Glossary: ​​Heavy metal markers: Metal substances that can leave obvious marks on film.

[0058] A method for X-ray positioning of defective welding spots in thick electron beam welds, such as Figures 2 to 7 As shown, the following steps are included:

[0059] S1. Use X-ray detection technology to perform the first penetration of the weld to find defects;

[0060] The X-ray detection technology is an X-ray vertical incidence positioning method, and its specific process is as follows:

[0061] Vertical incidence method Figure 3 , the radiation source and the film are separated on both sides of the object to be inspected, the film is close to the weld, the distance between the radiation source and the surface of the object to be inspected is not less than 800mm, the X-ray beam is emitted from the radiation source, vertically incident on the surface of the object to be inspected, and passes through the object to be inspected to reach the film, forming a film with defect information, so as to preliminarily determine the defect location;

[0062] S2. Marker arrangement, where the size and material of heavy metal markers are determined by the following methods:

[0063] Since cylindrical markers have the same effect at vertical and oblique incidence, which facilitates parameter adjustment, and square markers have an obviously unclear boundary at oblique incidence, it is recommended to choose cylindrical markers.

[0064] The diameter of the cylindrical marker affects the positioning accuracy. The smaller the diameter, the higher the positioning accuracy. However, the image resolution produced by the smaller diameter decreases. Therefore, the diameter of the marker should be selected according to the size of the defect to be detected and the thickness of the base material, while ensuring the image is clear. Due to the principle characteristics of X-ray itself, the minimum defect diameter that can be found is generally 2% of the penetration thickness. According to previous test results, the following formula exists based on the penetration thickness and the diameter of the heavy metal marker:

[0065]

[0066] in:

[0067] a: Projection length of the defect on the film

[0068] b: The distance from the lower end point of the upper marker to the measurement origin on the film

[0069] c: The length of the defect from the measurement origin

[0070] d: Diameter of heavy metal marker

[0071] F: Focal length

[0072] T: Transillumination thickness, approximately equal to the thickness of the base material of the object to be tested.

[0073] According to the principle of X-ray detection and imaging, the greater the difference between the radiation absorption coefficient of the marker and the base material to be detected, the easier it is to form a clear image. The most commonly used X-ray shielding material in daily work is lead, but due to its low hardness, lead is prone to deformation, which affects the measurement accuracy. In addition, when the atomic number is less than 40, the X-ray absorption coefficient of different elements increases with the increase of the atomic number, that is, the absorption coefficient of copper elements> the absorption coefficient of iron elements> the absorption coefficient of aluminum elements. Therefore, for aluminum alloy materials, choose a steel cylindrical marker; for steel materials, choose a copper cylindrical marker.

[0074] S3. Preliminary positioning of the relative position of the marker and the defect. According to the initial X-ray test results, place the upper and lower heavy metal markers on the upper and lower sides of the defect, and then use X-rays to verify the position of the markers and the defect. When X-rays are transmitted, use a plumb calibration beam to vertically incident on the weld surface, such as Figure 3 ;

[0075] S4. According to the preliminary transillumination results (such as Figure 4As shown in the left figure, adjust the positions of the upper and lower markers so that they overlap in the horizontal direction. The first iteration is completed through the above operation, so that the distance between the projection of the upper and lower markers and the projection of the defect is controlled within 5mm;

[0076] S5. Use X-rays to vertically incident on the weld surface for transillumination;

[0077] Use X-rays to vertically incident on the weld surface for transillumination;

[0078] According to the transillumination results after the first iteration (such as Figure 4 As shown in the middle figure, adjust the positions of the upper and lower markers again so that the projections of the upper and lower markers and the defects on the horizontal plane reach a higher degree of overlap than the first iteration. The second iteration is completed through the above operations;

[0079] If there is still a deviation in the horizontal projections of the three after the second iteration, one or more iterations are performed until the deviation of the three projection centers is less than 0.2 mm (e.g. Figure 4 Right picture and Figure 5 shown);

[0080] S6. Move the X-ray machine 1000-1200mm away from the weld, let the X-ray beam be incident on the defect and the marker obliquely, and the X-ray machine head height is 1000-1200mm away from the upper surface of the object to be measured, so that the direction of the X-ray forms an observable acute angle with the upper surface of the object to be measured, measure the distance from the X-ray machine head to the weld, and start the machine for transillumination;

[0081] S7, take off the film;

[0082] S8, darkroom processing of the film;

[0083] S9. The method for measuring and calculating the position and depth of the repair welding point is as follows: in the film image, the distance between the upper marker and the defect is defined as X, the distance between the lower marker and the defect is defined as Y, the defect diameter is defined as Z, and the thickness of the weld parent material to be tested is defined as R; according to the geometric relationship, it is calculated that the defect is X' from the upper surface of the weld parent material to be tested, and Y' from its lower surface. The method for determining the repair welding point is as follows: after the final iteration is completed, the upper and lower marker positions are determined, and the marker position that is closer to the defect is selected as the repair welding point; when repairing, all defects should be eliminated, so the repair welding depth should be greater than the distance between the defect and the upper surface + the defect diameter. X-ray detection finds that the defect has been eliminated and the product is qualified.

[0084] S10: Detection ends.

[0085] Another embodiment is:

[0086] S1. Use X-ray detection technology to perform the first penetration of the weld to find defects;

[0087] The X-ray detection technology is an X-ray vertical incidence positioning method. The vertical incidence method is as follows: Figure 3 , the radiation source and the film are separated on both sides of the object to be inspected, the film is close to the weld, the distance between the radiation source and the surface of the object to be inspected is not less than 800mm, the X-ray beam is emitted from the radiation source, vertically incident on the surface of the object to be inspected, and passes through the object to be inspected to reach the film, forming a film with defect information, so as to preliminarily determine the defect location;

[0088] S2, marker placement;

[0089] The method for selecting the heavy metal marker is:

[0090] Since cylindrical markers have the same effect at vertical and oblique incidence, which facilitates parameter adjustment, and square markers have an obviously unclear boundary at oblique incidence, it is recommended to choose cylindrical markers.

[0091] The diameter of the cylindrical marker affects the positioning accuracy. The smaller the diameter, the higher the positioning accuracy. However, the image resolution produced by the smaller diameter decreases. Therefore, the diameter of the marker should be selected according to the size of the defect to be detected and the thickness of the base material, while ensuring the image is clear. Due to the principle characteristics of X-ray itself, the minimum defect diameter that can be found is generally 2% of the penetration thickness. According to previous test results, the following formula exists based on the penetration thickness and the diameter of the heavy metal marker:

[0092]

[0093] in:

[0094] a: Projection length of the defect on the film

[0095] b: The distance from the lower end point of the upper marker to the measurement origin on the film

[0096] c: The length of the defect from the measurement origin

[0097] d: Diameter of heavy metal marker

[0098] F: Focal length

[0099] T: Transillumination thickness, approximately equal to the thickness of the base material of the object to be tested.

[0100] According to the principle of X-ray detection and imaging, the greater the difference between the radiation absorption coefficient of the marker and the base material to be detected, the easier it is to form a clear image. The most commonly used X-ray shielding material in daily work is lead, but due to its low hardness, lead is prone to deformation, which affects the measurement accuracy. In addition, when the atomic number is less than 40, the X-ray absorption coefficient of different elements increases with the increase of the atomic number, that is, the absorption coefficient of copper elements> the absorption coefficient of iron elements> the absorption coefficient of aluminum elements. Therefore, for aluminum alloy materials, choose a steel cylindrical marker; for steel materials, choose a copper cylindrical marker.

[0101] S3. Preliminary positioning of the relative position of the marker and the defect. According to the initial X-ray test results, place the upper and lower heavy metal markers on the upper and lower sides of the defect, and then use X-rays to verify the position of the markers and the defect. When X-rays are transmitted, use a plumb calibration beam to vertically incident on the weld surface, such as Figure 3 ;

[0102] S4. According to the preliminary transillumination results (such as Figure 4 As shown in the left figure, adjust the positions of the upper and lower markers so that they overlap in the horizontal direction. The first iteration is completed through the above operation, so that the distance between the projection of the upper and lower markers and the projection of the defect is controlled within 5mm;

[0103] S5. Use X-rays to vertically incident on the weld surface for transillumination;

[0104] Use X-rays to vertically incident on the weld surface for transillumination;

[0105] According to the transillumination results after the first iteration (such as Figure 4 As shown in the middle figure, adjust the positions of the upper and lower markers again so that the projections of the upper and lower markers and the defects on the horizontal plane reach a higher degree of overlap than the first iteration. The second iteration is completed through the above operations;

[0106] If there is still a deviation in the horizontal projections of the three after the second iteration, one or more iterations are performed until the deviation of the three projection centers is less than 0.2 mm (e.g. Figure 4 Right picture and Figure 5 shown);

[0107] S6. Move the X-ray machine 1000mm away from the weld, let the X-ray beam be incident on the defect and the marker obliquely, and the X-ray machine head is 1000mm away from the upper surface of the object to be tested, so that the direction of the X-ray forms an acute angle of 45° with the upper surface of the object to be tested, measure the distance from the X-ray machine head to the weld, and start the machine for transillumination;

[0108] S7, take off the film;

[0109] S8, darkroom processing of the film;

[0110] S9. The method for measuring and calculating the position and depth of the repair welding point is as follows: in the film image, the distance between the upper marker and the defect is defined as X, the distance between the lower marker and the defect is defined as Y, the defect diameter is defined as Z, and the thickness of the weld parent material to be tested is defined as R; according to the geometric relationship, it is calculated that the defect is X away from the upper surface of the weld parent material to be tested, and Y away from its lower surface. The method for determining the repair welding point is as follows: after the final iteration is completed, the upper and lower marker positions are determined, and the marker position that is closer to the defect is selected as the repair welding point; when repairing, all defects should be eliminated, so the repair welding depth should be greater than the distance between the defect and the upper surface + the defect diameter. X-ray detection finds that the defect has been eliminated and the product is qualified.

[0111] S10: Detection ends.

[0112] The third embodiment is:

[0113] S1. Use X-ray detection technology to perform the first penetration of the weld to find defects;

[0114] The X-ray detection technology is an X-ray vertical incidence positioning method. The vertical incidence method is as follows: Figure 3 , the radiation source and the film are separated on both sides of the object to be inspected, the film is close to the weld, the distance between the radiation source and the surface of the object to be inspected is not less than 800mm, the X-ray beam is emitted from the radiation source, vertically incident on the surface of the object to be inspected, and passes through the object to be inspected to reach the film, forming a film with defect information, so as to preliminarily determine the defect location;

[0115] S2, marker placement;

[0116] The method for selecting the heavy metal marker is:

[0117] Since cylindrical markers have the same effect at vertical and oblique incidence, which facilitates parameter adjustment, and square markers have an obviously unclear boundary at oblique incidence, it is recommended to choose cylindrical markers.

[0118] The diameter of the cylindrical marker affects the positioning accuracy. The smaller the diameter, the higher the positioning accuracy. However, the image resolution produced by the smaller diameter decreases. Therefore, the diameter of the marker should be selected according to the size of the defect to be detected and the thickness of the base material, while ensuring the image is clear. Due to the principle characteristics of X-ray itself, the minimum defect diameter that can be found is generally 2% of the penetration thickness. According to previous test results, the following formula exists based on the penetration thickness and the diameter of the heavy metal marker:

[0119]

[0120] in:

[0121] a: Projection length of the defect on the film

[0122] b: The distance from the lower end point of the upper marker to the measurement origin on the film

[0123] c: The length of the defect from the measurement origin

[0124] d: Diameter of heavy metal marker

[0125] F: Focal length

[0126] T: Transillumination thickness, approximately equal to the thickness of the base material of the object to be tested.

[0127] According to the principle of X-ray detection and imaging, the greater the difference between the radiation absorption coefficient of the marker and the base material to be detected, the easier it is to form a clear image. The most commonly used X-ray shielding material in daily work is lead, but due to its low hardness, lead is prone to deformation, which affects the measurement accuracy. In addition, when the atomic number is less than 40, the X-ray absorption coefficient of different elements increases with the increase of the atomic number, that is, the absorption coefficient of copper elements> the absorption coefficient of iron elements> the absorption coefficient of aluminum elements. Therefore, for aluminum alloy materials, choose a steel cylindrical marker; for steel materials, choose a copper cylindrical marker.

[0128] S3. Preliminary positioning of the relative position of the marker and the defect. According to the initial X-ray test results, place the upper and lower heavy metal markers on the upper and lower sides of the defect, and then use X-rays to verify the position of the markers and the defect. When X-rays are transmitted, use a plumb calibration beam to vertically incident on the weld surface, such as Figure 3 ;

[0129] S4. According to the preliminary transillumination results (such as Figure 4 As shown in the left figure, adjust the positions of the upper and lower markers so that they overlap in the horizontal direction. The first iteration is completed through the above operation, so that the distance between the projection of the upper and lower markers and the projection of the defect is controlled within 5mm;

[0130] S5. Use X-rays to vertically incident on the weld surface for transillumination;

[0131] Use X-rays to vertically incident on the weld surface for transillumination;

[0132] According to the transillumination results after the first iteration (such as Figure 4 As shown in the middle figure, adjust the positions of the upper and lower markers again so that the projections of the upper and lower markers and the defects on the horizontal plane reach a higher degree of overlap than the first iteration. The second iteration is completed through the above operations;

[0133] If there is still a deviation in the horizontal projections of the three after the second iteration, one or more iterations are performed until the deviation of the three projection centers is less than 0.2 mm (e.g. Figure 4 Right picture and Figure 5 shown);

[0134] S6. Move the X-ray machine 1000-1200mm away from the weld, let the X-ray beam be incident on the defect and the marker obliquely, and the X-ray machine head height is 1000-1200mm away from the upper surface of the object to be measured, so that the direction of the X-ray forms an observable acute angle with the upper surface of the object to be measured, measure the distance from the X-ray machine head to the weld, and start the machine for transillumination (such as Figure 6 );

[0135] S7, take off the film;

[0136] S8, darkroom processing of the film;

[0137] S9. The method for measuring and calculating the position and depth of the repair welding point is:

[0138] Based on X-ray detection, the defect position is determined according to the distance between the ray source and the object to be inspected, the size of the object to be inspected, the position of the upper and lower markers, the distance between the upper and lower markers and the defect, the thickness of the weld, the projection position of the upper and lower markers, and the relationship between similar triangles; A and C represent the positions of the upper and lower heavy metal markers respectively, and B represents the position of the defect. After the ray passes through, an image is formed on the film, where A' is the position of the projection of the upper marker, C' is the position of the projection of the lower marker, and C and C' are approximately coincident. B' is the position of the defect projection, so it can be obtained that △AA'C is similar to △BB'C (such as Figure 6 and Figure 7 ), and then we get the following relationship:

[0139] BC / B'C=AC / A'C……………………(2)

[0140] Formula (2) can be transformed into (3):

[0141] BC=AC·B'C / A'C……………………(3)

[0142] Since the AC length is approximately the weld thickness, the B'C length can be obtained by measuring the defect image on the film and the lower marker image, and the A'C length can be obtained by measuring the distance between the upper and lower marker images on the film. Therefore, the BC length can be calculated to determine the position of the defect distance from the upper and lower surfaces.

[0143] In one or more embodiments, specific test data is shown in Table 1 below.

[0144] Table 1 Test data statistics (unit: mm)

[0145]

[0146] The method for determining the repair welding point is as follows: after the final iteration is completed, the upper and lower marker positions are determined, and the marker position closer to the defect is selected as the repair welding point; when repairing welding, all defects should be eliminated, so the repair welding depth should be greater than the distance between the defect and the upper surface + the defect diameter. X-ray detection finds that the defect has been eliminated and the product is qualified.

[0147] S10: Detection ends.

[0148] The present invention finally realizes the repair welding positioning of defects in thick electron beam welds through a heavy metal marker selection method and an oblique incidence defect positioning method.

[0149] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for X-ray positioning of defective welding points of thick electron beam welds, characterized in that: The steps include: S1. Vertical transillumination was used for the first time to find defects; S2. Marker placement, including determination of the size and material of heavy metal markers; S3. Preliminary positioning of the relative position between the marker and the defect; S4, one iteration positioning; S5, iterating multiple times until the relative position of the positioning marker and the defect is adjusted; S6, oblique transillumination arrangement; S7, take off the film; S8, developing the film; S9, measuring and calculating the position of the repair welding point and the repair welding depth; S10: Detection ends.

2. The X-ray positioning method for defective repair welding points of thick electron beam welds according to claim 1 is characterized in that: S1. Use the X-ray vertical incidence positioning method to perform the first penetration of the weld. The specific method for finding defects is as follows: The radiation source and film are separated on both sides of the object to be inspected, the film is close to the weld, the distance between the radiation source and the surface of the object to be inspected is not less than 800mm, the X-ray beam is emitted from the radiation source, vertically incident on the surface of the object to be inspected, and passes through the object to be inspected to reach the film, forming a film with defect information, so as to preliminarily determine the defect location.

3. The X-ray positioning method for defects in thick electron beam welds according to claim 1, characterized in that: The method for determining the size and material of the heavy metal marker in S2 is: A1: Select cylindrical marker; A2: Under the premise of ensuring clear images, select the diameter of the marker according to the size of the defect to be detected and the thickness of the base material; A3: For aluminum alloy materials, choose steel cylindrical markers; for steel materials, choose copper cylindrical markers; A4: According to the transillumination thickness and the diameter of the heavy metal marker, there is the following formula: in: a: Projection length of the defect on the film; b: The distance from the image of the upper marker on the film to the measurement origin; c: The length of the defect from the measurement origin; d: diameter of heavy metal marker; F: focal length; T: Transillumination thickness, approximately equal to the base material thickness.

4. The X-ray positioning method for defective repair welding points of thick electron beam welds according to claim 1 is characterized in that: The method for preliminarily locating the relative position of the marker and the defect in S3 is: according to the position of the defect in S1, the upper and lower heavy metal markers are placed on the upper and lower sides of the defect, and then the marker and defect positions are verified by radiation. When the radiation is penetrated, a plumb calibration beam is used to vertically irradiate the weld surface.

5. The X-ray positioning method for defective repair welding points of thick electron beam welds according to claim 1 is characterized in that: The method for one iteration positioning in S4 is: According to the preliminary radiography results, the positions of the upper and lower markers were adjusted so that they overlapped in the horizontal direction. The first iteration was completed through the above operation so that the distance between the projection of the upper and lower markers and the projection of the defect was controlled within 5 mm.

6. The X-ray positioning method for defective repair welding points of thick electron beam welds according to claim 1 is characterized in that: The specific method of multiple iterations in S5 until the relative position of the positioning marker and the defect is adjusted is: Use X-rays to vertically incident on the weld surface for transillumination; According to the transillumination result after the first iteration, the positions of the upper and lower markers are adjusted again so that the projections of the upper and lower markers and the defects on the horizontal plane reach a higher degree of overlap than that of the first iteration. The second iteration is completed through the above operation; Then, X-rays are vertically incident on the weld surface for transillumination; If there is still a deviation in the horizontal projections of the three after the second iteration, one or more iterations are performed until the deviation in the centers of the three projections is less than 0.2 mm.

7. The X-ray positioning method for defective repair welding points of thick electron beam welds according to claim 1 is characterized in that: The specific method of arranging the oblique radiation in S6 is as follows: move the X-ray machine away from the weld by 1000-1200 mm, let the radiation beam be incident on the defect and the marker obliquely, and the height of the X-ray machine head is 1000-1200 mm away from the upper surface of the object to be measured, so that the radiation direction forms an acute angle of observation with the upper surface of the object to be measured.

8. The X-ray positioning method for defective repair welding points of thick electron beam welds according to claim 7, characterized in that: The oblique incident observation acute angle of the ray beam is 45°.

9. The X-ray positioning method for defective repair welding points of thick electron beam welds according to claim 1, characterized in that: The method for measuring and calculating the position of the repair welding point and the repair welding depth in S9 is: In the film image, the distance between the upper marker and the defect is defined as X, the distance between the lower marker and the defect is defined as Y, the defect diameter is defined as Z, and the thickness of the weld parent material to be tested is defined as R; according to the geometric relationship, it is calculated that the distance between the defect and the upper surface of the weld parent material to be tested is X', and the distance to its lower surface is Y'. The method for determining the repair welding point is: after the final iteration is completed, the upper and lower marker positions are determined, and the marker position closer to the defect is selected as the repair welding point; During repair welding, all defects should be eliminated, so the repair welding depth should be greater than the distance between the defect and the upper surface + the diameter of the defect. X-ray inspection shows that the defects have been eliminated and the product is qualified.

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