A method of radiographic calculation of linear flaw depth

Abstract

The application discloses a kind of linear defect depth's ray detection calculation method, comprising the following steps: special positioning mark is made;Special positioning mark includes several with the same point as center outward radial distribution branch;Part is once penetrated, and once penetrated negative is obtained, and the object distance f and focal length F are determined;Linear defect fitting line is obtained by linear fitting to linear defect on once penetrated negative, according to the direction of linear defect fitting line, the branch of special positioning mark is selected and is parallel to linear defect fitting line, and the vertical distance L1 of the branch of special positioning mark and linear defect fitting line is measured;According to the normal direction of linear defect overall trend, part is parallelly displaced, and the parallel displacement distance W is displaced;Part after parallel displacement is twice penetrated, and twice penetrated negative is obtained, and linear defect fitting line is obtained by linear fitting to linear defect on twice penetrated negative, the branch of special positioning mark is selected and is parallel to linear defect fitting line, and the vertical distance L2 between the branch of special positioning mark and linear defect fitting line is measured;Linear defect depth is calculated according to the following public demonstration:。

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of aero-engine defect detection, and particularly relates to a linear defect depth radiographic detection calculation method. BACKGROUND

[0002] Linear defects can be generated at welding positions or base material positions of an aero-engine during manufacturing, use and repair. A general repair method is to remove the linear defects by grinding and then repair the linear defects by welding. During the removal process, if the removal amount is insufficient, the linear defects cannot be completely eliminated, and if the removal amount is too large, the base material can be easily penetrated, which causes difficulty in subsequent welding. A general detection method is radiographic detection vertical penetration, which can only find the planar position and cannot determine the depth. The depth cannot be determined due to the principle of radiographic detection. Radiographic detection converts three dimensions into two dimensions. The radiographic detection penetrates a workpiece from a specific direction. Internal defects can absorb or scatter the radiographic detection. The energy of the penetrated radiographic detection is recorded by a film, and finally a two-dimensional image is formed. However, only the planar coordinates can be determined, and the depth information cannot be recorded, which causes that the removal amount cannot be determined during the repair process, and the removal amount that is too large or insufficient cannot meet the repair needs. SUMMARY

[0003] The present application aims to overcome the shortcomings of the prior art and provide a linear defect depth radiographic detection calculation method.

[0004] The present application is achieved by the following technical scheme: a linear defect depth radiographic detection calculation method, comprising the following steps.

[0005] Step one: special positioning marks are made according to the material and thickness of a part; the special positioning marks comprise a plurality of branches distributed radially outward from a same point;

[0006] Step two: radiographic detection parameters are determined according to the material and thickness of the part, and one-time penetration is performed to obtain a one-time penetration negative, and the object distance f and the focal distance F are determined;

[0007] Step three: linear fitting is performed on the linear defects on the one-time penetration negative to obtain a linear defect fitting line, a special positioning mark branch parallel to the linear defect fitting line is selected according to the direction of the linear defect fitting line, and the perpendicular distance L1 between the special positioning mark branch and the linear defect fitting line is measured;

[0008] Step four: the part is parallelly displaced according to the normal direction of the overall trend of the linear defects, and the parallel displacement distance W is measured;

[0009] Step five, the second transmission of the parts after parallel displacement is carried out, and a second transmission negative is obtained. Linear defects fitting lines are obtained by linear fitting of linear defects on the second transmission negative. A special positioning mark branch parallel to the linear defects fitting lines is selected, and the vertical distance L2 between the special positioning mark branch and the linear defects fitting lines is measured.

[0010] Step six, according to the parallel displacement distance W, the part thickness T, the object distance f, L1, L2, the linear defect depth is calculated according to the following trigonometric function relationship:

[0011] ;

[0012] The part thickness T is 5-85 mm.

[0013] The parallel displacement distance W is 2 / F, wherein F=f+T. If the parallel displacement distance is small, the difference between L1 and L2 is small and it is not convenient to calculate. If the parallel displacement distance is large, it will exceed the range of the ray detection.

[0014] The special positioning mark includes 12 branches, each branch has a length of 100 mm, and the interval between adjacent two branches is 15°.

[0015] The branch is a metal wire with a width of 0.32-1.00 mm, and the material is any one of high-temperature alloy, low-carbon steel and aluminum alloy. If the width of the branch is less than 0.32 mm, it cannot be seen on the negative after the ray detection. If the width of the branch is greater than 1.00 mm, the error is large when the distance is measured.

[0016] The relationship between the part thickness and the width of the special positioning mark is as follows: when the part thickness is 5-15 mm, the width of the special positioning mark branch is 0.32 mm; when the part thickness is 15-32 mm, the width of the special positioning mark branch is 0.50 mm; when the part thickness is 32-55 mm, the width of the special positioning mark branch is 0.80 mm; and when the part thickness is 55-85 mm, the width of the special positioning mark branch is 1.00 mm.

[0017] The linear fitting specifically includes the following steps:

[0018] A. According to the linear type of the linear defect, a plurality of initial feature points are selected on the line of the linear defect at equal intervals, and the initial feature points are uniformly distributed along the length direction of the linear defect.

[0019] B. Connecting adjacent initial feature points with line segments, taking the midpoints of the line segments, obtaining the midpoints between adjacent initial feature points, and forming a first set of midpoints.

[0020] C. If the number of midpoints in the first set of midpoints is greater than 2 after step B, connecting adjacent midpoints with line segments, taking the midpoints of the line segments, and forming a second set of midpoints.

[0021] D, repeat step C until only two points are left in the midpoint set of the nth group, and the line segment connecting the two points is the linear defect fitting line;

[0022] If the linear defect is a straight line, four equidistant initial feature points are selected, and the distance between adjacent two initial feature points is 1 / 3 of the total length of the line;

[0023] If the linear defect is a polyline, six equidistant initial feature points are selected, and the distance between adjacent two initial feature points is 1 / 5 of the total length of the line;

[0024] If the linear defect is a curve, eight equidistant initial feature points are selected, and the distance between adjacent two initial feature points is 1 / 7 of the total length of the line;

[0025] If the selected special positioning marks are different after twice radiographic examination, L2 is the vertical distance between the midpoint of the linear defect fitting line after twice radiographic examination and the selected branch after once radiographic examination, the angle difference θ between the linear defect fitting line after once radiographic examination and the linear defect fitting line after twice radiographic examination is measured, the linear defect fitting line is extended at both ends, the vertical lines from the initial feature points at both ends of the linear defect to the fitting line are drawn, and the vertical distance between the two vertical lines is l. The maximum penetration depth is calculated according to the following formula:

[0026] ;

[0027] The maximum penetration depth refers to the vertical distance between the highest point and the lowest point of the linear defect in the height direction.

[0028] The present application has the following advantages:

[0029] 1. The present application realizes the ray detection and calculation of the linear defect depth by making special positioning marks and then performing twice linear translation vertical ray radiographic examination in specific directions according to the trigonometric function relationship, which is beneficial to determine the polishing removal amount during repair and avoid excessive or insufficient polishing amount.

[0030] 2. The present application can calculate the maximum penetration depth of the non-planar linear defect, such as the vertical distance between the highest point and the lowest point of the inclined linear defect in the height direction, through linear defect fitting. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 It is a structural schematic diagram of a special positioning mark.

[0032] Figure 2 It is a schematic diagram of a once radiographic film.

[0033] Figure 3Schematic view of the second radiographic film.

[0034] Figure 4 Schematic view of the two radiographic systems.

[0035] Figure 5 Schematic view of the linear fitting process.

[0036] In the figure: S1 is the first radiographic source position; S2 is the second radiographic source position; Q is the actual position of the special positioning mark; X is the actual position of the defect; Q1 is the position of the special positioning mark on the first radiographic film; Q2 is the position of the special positioning mark on the second radiographic film; X1 is the position of the linear defect on the first radiographic film; X2 is the position of the linear defect on the second radiographic film. DETAILED DESCRIPTION

[0037] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application but not all the embodiments. The components of the embodiments of the present application described and shown in the accompanying drawings can be arranged and designed in various different configurations.

[0038] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0039] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0040] It should be noted that: similar reference numerals and letters represent similar items in the following drawings, therefore, once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings.

[0041] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use, or the orientation or positional relationship commonly understood by those skilled in the art. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. In addition, the terms "first," "second," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0042] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0043] Example 1: As Figures 1-5 As shown, a method for calculating the depth of a linear defect using X-ray inspection includes the following steps:

[0044] Step 1: Create special positioning marks according to the material and thickness of the part; the special positioning marks include several branches that radiate outward from the same point;

[0045] Step 2: Determine the X-ray inspection parameters based on the material and thickness of the part, and perform a radiographic test to obtain a radiographic film, and determine the object distance f and focal length F;

[0046] Step 3: Perform linear fitting on the linear defects on the radiograph to obtain the linear defect fitting line. Based on the direction of the linear defect fitting line, select a special positioning mark branch that is parallel to the linear defect fitting line, and measure the vertical distance L1 between the special positioning mark branch and the linear defect fitting line.

[0047] Step 4: Perform parallel displacement on the part according to the normal direction of the overall linear defect, with a parallel displacement distance W.

[0048] Step 5: Perform a second radiograph on the part after parallel displacement to obtain a second radiograph film. Perform linear fitting on the linear defects on the second radiograph film to obtain a linear defect fitting line. Select a special positioning mark branch that is parallel to the linear defect fitting line and measure the vertical distance L2 between the special positioning mark branch and the linear defect fitting line.

[0049] Step six, according to the parallel displacement distance W, the part thickness T, the object distance f, L1, L2, the linear defect depth is calculated according to the following trigonometric function relationship:

[0050] ;

[0051] The part thickness T is 5-85mm;

[0052] The parallel displacement distance W is 2 / F, wherein F=f+T;

[0053] The special positioning mark includes 12 branches, each branch length is 100mm, and the interval between adjacent two branches is 15°;

[0054] The branch is a metal wire with a width of 0.32-1.00mm, and the material is any one of high-temperature alloy, low-carbon steel and aluminum alloy;

[0055] The relationship between the part thickness and the width of the special positioning mark is that when the part thickness is 5-15mm, the branch width of the special positioning mark is 0.32mm; when the part thickness is 15-32mm, the branch width of the special positioning mark is 0.50mm; when the part thickness is 32-55mm, the branch width of the special positioning mark is 0.80mm; and when the part thickness is 55-85mm, the branch width of the special positioning mark is 1.00mm;

[0056] The linear fitting specifically includes the following steps:

[0057] A. According to the line type of the linear defect, a plurality of initial feature points are selected on the line of the linear defect at equal intervals, and the initial feature points are uniformly distributed along the length direction of the linear defect;

[0058] B. Connecting adjacent initial feature points with a line segment, taking the midpoint of each line segment, obtaining the midpoint between adjacent initial feature points, and forming a first set of midpoints;

[0059] C. If the number of midpoints in the first set of midpoints is greater than 2 after step B, connecting adjacent midpoints with a line segment, taking the midpoint of each line segment, forming a second set of midpoints;

[0060] D. Repeat step C until there are only two points in the nth set of midpoints, and the line segment connecting the two points is the fitting line of the linear defect;

[0061] If the line type of the linear defect is a straight line, 4 initial feature points at equal intervals are selected, and the interval between adjacent two initial feature points is 1 / 3 of the total length of the line;

[0062] If the linear defect is a broken line, then select 6 equally spaced initial feature points, with the distance between two adjacent initial feature points being 1 / 5 of the total line length;

[0063] If the linear defect is a curve, then select 8 equidistant initial feature points, with the distance between two adjacent initial feature points being 1 / 7 of the total line length.

[0064] If the selected dedicated positioning marker branches are different after the two radiographs, then L2 is the perpendicular distance between the midpoint of the linear defect fitting line after the second radiograph and the selected branch after the first radiograph. Measure the angle difference θ between the linear defect fitting lines after the first and second radiographs. Extend both ends of the linear defect fitting line after the first radiograph to obtain the fitting line. Draw perpendicular lines from the initial feature points at both ends of the linear defect to the fitting line. The perpendicular distance between the two perpendicular lines is l. Calculate the maximum penetration depth according to the following formula:

[0065] ;

[0066] The maximum penetration depth refers to the vertical distance between the highest and lowest points of the linear defect in the height direction.

[0067] Example 2: As Figures 1-5 As shown, a method for calculating the depth of a linear defect using X-ray inspection specifically includes the following steps:

[0068] Step 1: Create special positioning marks according to the material and thickness of the part; the special positioning marks include several branches that radiate outward from the same point;

[0069] Step 2: Determine the X-ray inspection parameters based on the material and thickness of the part, and perform a radiographic test to obtain a radiographic film, and determine the object distance f and focal length F;

[0070] Step 3: Perform linear fitting on the linear defects on the radiograph to obtain the linear defect fitting line. Based on the direction of the linear defect fitting line, select a special positioning mark branch that is parallel to the linear defect fitting line, and measure the vertical distance L1 between the special positioning mark branch and the linear defect fitting line.

[0071] Step 4: Perform parallel displacement on the part according to the normal direction of the overall linear defect, with a parallel displacement distance W.

[0072] Step 5: Perform a second radiograph on the part after parallel displacement to obtain a second radiograph film. Perform linear fitting on the linear defects on the second radiograph film to obtain a linear defect fitting line. Select a special positioning mark branch that is parallel to the linear defect fitting line and measure the vertical distance L2 between the special positioning mark branch and the linear defect fitting line.

[0073] Step six, according to the parallel displacement distance W, the part thickness T, the object distance f, L1, L2, the linear defect depth is calculated according to the following trigonometric function relationship:

[0074] ;

[0075] The parallel displacement distance W is 2 / F, wherein F=f+T;

[0076] The special positioning mark includes 12 branches, each branch has a length of 100 mm, and adjacent two branches are spaced apart by 15°;

[0077] The linear fitting specifically includes the following steps:

[0078] A. According to the line type of the linear defect, a plurality of initial feature points are selected on the line of the linear defect at equal intervals, and the initial feature points are uniformly distributed along the length direction of the linear defect;

[0079] B. Connecting adjacent initial feature points with a line segment, taking the midpoint of each line segment, obtaining the midpoint between adjacent initial feature points, and forming a first set of midpoints;

[0080] C. If the number of midpoints in the first set of midpoints is greater than 2 after step B, connecting adjacent midpoints with a line segment, taking the midpoint of each line segment, forming a second set of midpoints;

[0081] D. Repeat step C until only two points are left in the nth set of midpoints, and the line segment obtained by connecting the two points is the fitting line of the linear defect;

[0082] If the selected special positioning mark branches are different after twice transillumination, L2 is the vertical distance between the midpoint of the linear defect fitting line after twice transillumination and the selected branch after once transillumination, the angle difference θ between the linear defect fitting line after once transillumination and the linear defect fitting line after twice transillumination is measured, the linear defect fitting line is extended at both ends to obtain a fitting line, the vertical lines from the initial feature points at both ends of the linear defect to the fitting line are drawn, and the vertical distance between the two vertical lines is l. The maximum penetration depth is calculated according to the following formula:

[0083] ;

[0084] In this embodiment, the part material is a high-temperature alloy, the thickness is 6 mm, the special positioning mark is made of a high-temperature alloy, and the width is 0.32 mm. Transillumination is performed by using a voltage of 130 kv, a current of 10 mA, an exposure time of 3 min, F=2000 mm, and f=1994 mm.

[0085] The linear defect of the part in the embodiment is straight line type, and the initial point is divided into three segments, marked as A1, A2, A3 and A4. Iteration: connecting A1-A2 to get midpoint M1, connecting A2-A3 to get endpoint M2, and connecting A3-A4 to get midpoint M3. Drawing: second iteration: connecting M1-M2 to get midpoint N1, connecting M2-M3 to get midpoint N2, and connecting N1-N2 to get the linear defect fitting line.

[0086] In step three, the linear defect on the primary transmission film is parallel to the branch of the special positioning mark at 30°, and the measurement L1 is 3mm. In step four, the part is translated along the normal direction of the overall trend of the linear defect by 1000mm. In step five, the measurement L2 is 4.5mm, the primary transmission film and the secondary transmission film are overlapped, the angle difference θ between the linear defect fitting line after the primary transmission and the linear defect fitting line after the secondary transmission is 0, and the penetration depth does not need to be calculated. In step six, according to the parallel displacement distance W of 1000mm, the part thickness T of 6mm, the object distance f of 1994mm, the focal length F of 2000mm, L1 of 3mm and L2 of 4.5mm, the defect depth is calculated according to the following trigonometric function relationship:

[0087] 。

[0088] The calculated defect depth h is 3mm, that is, the linear defect depth is 3mm.

[0089] Although the present application is described in detail with reference to the foregoing embodiments, those skilled in the art can modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement to part of the technical features, and any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for calculating the depth of linear defects using X-ray inspection, characterized in that, Includes the following steps: Step 1: Create special positioning marks according to the material and thickness of the part; the special positioning marks include several branches that radiate outward from the same point; Step 2: Determine the X-ray inspection parameters based on the material and thickness of the part, and perform a radiographic test to obtain a radiographic film, and determine the object distance f and focal length F; Step 3: Perform linear fitting on the linear defects on the radiograph to obtain the linear defect fitting line. Based on the direction of the linear defect fitting line, select a special positioning mark branch that is parallel to the linear defect fitting line, and measure the vertical distance L1 between the special positioning mark branch and the linear defect fitting line. Step 4: Perform parallel displacement on the part according to the normal direction of the overall linear defect, with a parallel displacement distance W. Step 5: Perform a second radiograph on the part after parallel displacement to obtain a second radiograph film. Perform linear fitting on the linear defects on the second radiograph film to obtain a linear defect fitting line. Select a special positioning mark branch that is parallel to the linear defect fitting line and measure the vertical distance L2 between the special positioning mark branch and the linear defect fitting line. Step Six: Based on the parallel displacement distance W, part thickness T, object distance f, L1, L2, calculate the linear defect depth using the following trigonometric function relationships: 。 2. The X-ray inspection calculation method for linear defect depth according to claim 1, characterized in that, The thickness T of the part is 5 to 85 mm.

3. The method for calculating the linear defect depth using X-ray inspection according to claim 1, characterized in that, The parallel displacement distance W is 2 / F, where F = f + T.

4. The method for calculating the linear defect depth using X-ray inspection according to claim 1, characterized in that, The dedicated positioning mark includes 12 branches, each branch is 100mm long, and the interval between two adjacent branches is 15°.

5. The X-ray inspection calculation method for linear defect depth according to claim 4, characterized in that, The branch is a metal wire with a width of 0.32 to 1.00 mm, and the material is any one of high-temperature alloy, low-carbon steel, and aluminum alloy.

6. The method for calculating the linear defect depth using X-ray inspection according to claim 5, characterized in that, The relationship between part thickness and the width of the special positioning mark branch is as follows: when the part thickness is 5-15mm, the width of the special positioning mark branch is 0.32mm; when the part thickness is 15-32mm, the width of the special positioning mark branch is 0.50mm; when the part thickness is 32-55mm, the width of the special positioning mark branch is 0.80mm; and when the part thickness is 55-85mm, the width of the special positioning mark branch is 1.00mm.

7. The method for calculating the linear defect depth using X-ray inspection according to claim 1, characterized in that, Linear fitting specifically includes the following steps: A. Based on the line shape of the linear defect, select several initial feature points at equal intervals on the line of the linear defect. The initial feature points are evenly distributed at equal intervals along the length direction of the linear defect. B. Connect adjacent initial feature points with line segments, take the midpoint of each line segment, obtain the midpoint between each adjacent initial feature point, and form the first set of midpoints. C. If, after step B, the number of midpoints in the first set of midpoints is greater than 2, then connect the adjacent midpoints with line segments, take the midpoint of each line segment, and form the second set of midpoints. D. Repeat step C until only two points remain in the midpoint set of the nth group. The line segment obtained by connecting the two points is the linear defect fitting line. If the linear defect is a straight line, then select 4 equidistant initial feature points, with the distance between two adjacent initial feature points being 1 / 3 of the total line length; If the linear defect is a broken line, then select 6 equally spaced initial feature points, with the distance between two adjacent initial feature points being 1 / 5 of the total line length; If the linear defect is a curve, then select 8 equidistant initial feature points, with the distance between two adjacent initial feature points being 1 / 7 of the total line length.

8. The method for calculating the linear defect depth using X-ray inspection according to claim 7, characterized in that, If the selected dedicated positioning marker branches are different after the two radiographs, then L2 is the perpendicular distance between the midpoint of the linear defect fitting line after the second radiograph and the branch selected after the first radiograph; measure the angle difference θ between the linear defect fitting lines after the first radiograph and the second radiograph, extend both ends of the linear defect fitting line after the first radiograph to obtain the fitting line, draw the perpendicular lines from the initial feature points at both ends of the linear defect to the fitting line, and the perpendicular distance between the two perpendicular lines is l. Calculate the maximum penetration depth according to the following formula: ； The maximum penetration depth refers to the vertical distance between the highest and lowest points of the linear defect in the height direction.

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