A method for detecting brazing defects by water immersion ultrasonic C-scan with refracted waves perpendicular to the brazing surface

Abstract

The present invention discloses a method for detecting brazing defects by water immersion ultrasonic C-scan with a refracted wave perpendicular to the brazing surface. The specific process is as follows: Obtain the scanning points on the brazing surface; Based on the constraint conditions of the refracted wave perpendicular to the scanning points of the brazed part to be measured, calculate the incident points and the unit vectors of the incident wave directions on the incident surface corresponding to each scanning point, and calculate the detection trajectory of the water immersion ultrasonic testing equipment according to the incident points and the unit vectors of the incident wave directions; Perform ultrasonic C-scan testing on the brazed part to be measured according to the detection trajectory, and use the obtained ultrasonic C-scan image of the brazing surface to realize the defect detection of the brazed part to be measured. The present invention can obtain the defect echo of the brazing surface and realize the detection of brazing defects.

Description

Technical Field

[0001] The present invention belongs to the technical field of measurement and control, and particularly relates to a method for detecting brazing defects by water immersion ultrasonic C with a refracted wave perpendicular to the brazing surface. Background Art

[0002] Under the development trend of the integration, lightweight, low cost and high reliability of product structures, welded structures are widely used in industrial fields such as aerospace, automotive, shipbuilding, nuclear energy, and electronics. The brazing technology has attracted the attention of the manufacturing industry due to its advantages such as simple equipment, small post-welding deformation, and high productivity. During the brazing process, due to the combined action of various complex factors such as brazing materials, processes, and environments, defects such as pores, lack of fusion, and cracks often occur in the joints. The existence of brazing defects directly affects the service performance, reliability, and safety of products. The impeller is one of the important components of an aerospace engine and is connected to the cover plate by brazing. Its welding quality directly affects the overall service life and safety performance of the engine.

[0003] Currently, ultrasonic C-scan is usually used to detect brazing defects. However, for brazed components with complex structures, where the brazing surface is not parallel to the incident surface, when using the traditional ultrasonic C-scan method with perpendicular incidence to the incident surface, the refracted wave obliquely enters the brazing surface, and the defect echo of the brazing surface cannot be obtained, so the detection of brazing defects cannot be achieved. Summary of the Invention

[0004] In view of this, the present invention provides a method for detecting brazing defects by water immersion ultrasonic C with a refracted wave perpendicular to the brazing surface, so that the refracted wave of the sound beam obliquely incident on the incident surface in the medium can be perpendicular to the scanning point of the brazing surface, and the defect echo of the brazing surface can be obtained to achieve the detection of brazing defects.

[0005] The present invention is realized by the following technical solutions:

[0006] A method for detecting brazing defects by water immersion ultrasonic C with a refracted wave perpendicular to the brazing surface, the specific process of the method for detecting brazing defects is as follows:

[0007] Obtain the scanning points of the brazing surface;

[0008] Based on the constraint condition that the refracted wave is perpendicular to the scanning points of the brazed part to be measured, calculate the incident points on the incident surface and the unit vector of the incident wave direction corresponding to each scanning point, and calculate the detection trajectory of the water immersion ultrasonic detection device according to the incident points and the unit vector of the incident wave direction;

[0009] Perform ultrasonic C-scan detection on the brazed part to be measured according to the detection trajectory, and use the obtained ultrasonic C-scan image of the brazing surface to realize the defect detection of the brazed part to be measured.

[0010] Further, for each scanning point, a gain compensation value is obtained based on the propagation distance of the refracted wave and / or the incident angle of the corresponding incident wave, and the ultrasonic detection result is gain-compensated.

[0011] Further, the gain compensation value is obtained by determining an amplitude attenuation curve according to the echo amplitude values corresponding to different refracted wave propagation distances and different incident angles, and calculating the gain compensation value at each incident point according to the amplitude attenuation curve;

[0012] The amplitude attenuation curve is obtained by means of independent tests using a test block made of the same material as the brazed part to be measured.

[0013] Further, the amplitude attenuation curve is obtained as follows:

[0014] Independent tests are carried out using a test block made of the same material as the brazed part to be measured. The incident angle of the incident wave and the propagation distance of the refracted wave in the test block are changed, and the echo signal amplitudes are collected and recorded. An amplitude attenuation curve is plotted with the incident angle as the abscissa and the echo signal amplitude as the ordinate.

[0015] Further, the steps of obtaining the incident point and the unit vector of the incident wave direction, and calculating the detection trajectory of the immersion ultrasonic testing equipment according to the incident point and the unit vector of the incident wave direction are as follows:

[0016] Step 1: Obtain the profile information of the brazing surface from the three-dimensional model of the brazed part to be measured, discretize the brazing surface at equal intervals, and obtain the information of each scanning point on the brazing surface;

[0017] Step 2: Extract the profile information of the incident surface of the brazed part to be measured. Based on the constraint condition that the refracted wave is perpendicular to the scanning points on the brazed part to be measured, calculate each incident point and the corresponding unit vector of the incident wave direction according to the information of each scanning point on the brazing surface obtained in Step 1, the profile information of the incident surface, and Snell's law;

[0018] Step 3: According to the incident points and the unit vectors of the incident wave direction corresponding to each scanning point on the brazing surface calculated in Step 2, calculate the probe position coordinates where the refracted wave is incident perpendicular to the brazing surface according to the set water path of the probe design, generate the probe position and direction trajectory, and convert the probe position and direction trajectory into an ultrasonic detection trajectory that the ultrasonic equipment can execute.

[0019] Further, in Step 1, the information of each scanning point on the brazing surface includes the scanning point coordinates and the unit normal vector of the scanning point. The specific steps of Step 1 are as follows:

[0020] Extract the profile information of the brazing surface of the brazing part to be measured, select the Cartesian coordinate system as the workpiece coordinate system, and obtain the profile analytical formula of the brazing surface; discretize each point on the brazing surface according to the profile analytical formula of the brazing surface to obtain the coordinates of each scanning point, and obtain the unit normal vector of each scanning point.

[0021] Further, the specific steps of the second step are as follows:

[0022] Step 2-1: Extract the profile information of the incident surface of the brazing part to be measured, select the same Cartesian workpiece coordinate system as in the first step, and obtain the profile analytical formula of the incident surface;

[0023] Step 2-2, based on the constraint condition that the refracted wave is perpendicular to the scanning point of the brazing part to be measured, according to the coordinates of each scanning point on the brazing surface, the unit vector of the echo direction, and the profile analytical formula of the incident surface, for any scanning point on the brazing surface, obtain the corresponding incident point on the incident surface;

[0024] Step 2-3, through the profile analytical formula of the incident surface, obtain the normal vector corresponding to each incident point, calculate the refraction angle corresponding to each incident point according to Snell's law; according to the normal vector corresponding to each incident point and the refraction angle corresponding to each incident point, calculate the incident angle and the unit vector of the incident wave direction corresponding to each incident point through Snell's law.

[0025] Further, the specific steps of the third step are as follows:

[0026] Step 3-1, calculate the probe position coordinates corresponding to each incident point according to the coordinates of each incident point, the probe incident direction vector, and the designed water path of the probe;

[0027] Step 3-2, combine each set of probe position coordinates and its corresponding set of probe incident direction vectors to generate the probe position and direction trajectory;

[0028] Step 3-3, convert the probe position and direction trajectory into an ultrasonic detection trajectory that can be executed by the ultrasonic device.

[0029] Further, for the ultrasonic detection device that uses the method of mechanically gripping the probe or directly uses an ultrasonic scanning device with 5 axes or more, the steps of converting the probe position and direction trajectory into an ultrasonic detection trajectory that can be executed by the manipulator are as follows:

[0030] Select the posture of the workpiece;

[0031] According to the unit vectors of the probe incident direction, the scanning direction, and the indexing direction corresponding to each incident point, for the coordinate system with the end effector of the manipulator as the origin, the probe incident direction is the z direction, the probe scanning direction is the x direction, and the indexing direction is the y direction, obtain the rotation matrix of the end effector of the manipulator relative to the origin of the workpiece coordinate system;

[0032] Then, according to the rotation matrix, the pose of the end effector of the manipulator is transformed into a pose with a rotation angle, a pitch angle, and a yaw angle in a fixed X-Y-Z angular coordinate system, so as to obtain the position information of the end trajectory of the manipulator.

[0033] Finally, the obtained end trajectory of the manipulator is simulated by a manipulator simulation software to eliminate dangerous factors such as singular points and interferences, and form the final ultrasonic detection trajectory for the complex surface workpiece.

[0034] Furthermore, according to the incident angles corresponding to each incident point obtained in step two, and based on the amplitude attenuation curve, the echo gain compensation value is designed. The specific implementation process of this step is as follows:

[0035] According to the propagation distance and the incident angle of the ultrasonic wave at the incident point of the brazing workpiece to be measured in the brazing workpiece to be measured, the echo signal amplitude corresponding to the incident point is obtained in the amplitude attenuation curve.

[0036] The ultrasonic energy attenuation value is obtained by using the difference method.

[0037] The gain compensation value db corresponding to each incident point i is obtained by using the following formula:

[0038] (db i ) = 20log(100 / (ultrasonic energy attenuation value))

[0039] The gain compensation value db at the incident surface is calculated. i .

[0040] Beneficial effects:

[0041] (1) By establishing the constraint condition that the refracted wave is perpendicular to the brazing workpiece to be measured, the detection trajectory of the immersion ultrasonic testing equipment is calculated in the present invention. After the sound beam is obliquely incident on the incident surface of the brazing workpiece, its refracted longitudinal wave can be perpendicular to the scanning point of the brazing surface. When there are brazing defects, reflection will occur and defect echoes will be generated, ensuring the effective acquisition of brazing defect echoes.

[0042] (2) In the present invention, distance and / or angle gain compensation is performed on each scanning point of the brazing surface, so that the defect detection sensitivity of each scanning point is consistent, thereby improving the detection accuracy of ultrasonic C for brazing defects and overcoming the problem of large energy differences of refracted waves caused by different incident angles of the incident surface corresponding to the scanning points when both the incident surface and the brazing surface are curved surfaces.

[0043] (3) The present invention determines the gain compensation value according to the amplitude attenuation curve. The amplitude attenuation curve only needs to be measured once on a test block with the same material as the brazed part, and the measured amplitude attenuation curve is stored. Therefore, for the same material, only one measurement is required, and the measured amplitude attenuation curve can be used multiple times.

[0044] (4) The present invention adopts the method of gain compensation for the scanning points where the refracted wave is perpendicular to the brazing surface, the distance, and the angle. After defect detection, the obtained image has clear brazing boundaries and prefabricated defects, and is applicable to the detection of brazed components with complex structures. Description of the Drawings

[0045] Figure 1 is the front sectional view of the upper cover plate of the impeller;

[0046] Figure 2 is the top view of the upper cover plate of the impeller;

[0047] Figure 3 is the schematic diagram of the sound wave propagation path where the refracted wave is perpendicular to the brazing surface;

[0048] Figure 4 is the probe sound ray diagram;

[0049] Figure 5 is the probe trajectory diagram;

[0050] Figure 6 is the amplitude attenuation curve;

[0051] Figure 7 is the screenshot of the gain compensation table;

[0052] Figure 8 is the ultrasonic C-scan image Ⅰ (incident wave perpendicular to the incident surface) of the simulated brazed component with artificial defects;

[0053] Figure 9 is the ultrasonic C-scan image Ⅱ (refracted wave perpendicular to the brazing surface) of the simulated brazed component with artificial defects;

[0054] Figure 10 is the ultrasonic C-scan image Ⅲ (refracted wave perpendicular to the brazing surface and additional gain compensation) of the simulated brazed component with artificial defects.

[0055] 1 - Outer surface of the upper cover plate of the impeller, 2 - Bottom ribs, 3 - Inner surface of the upper cover plate of the impeller, 4 - Probe. Detailed Embodiment

[0056] The following examples are given in conjunction with the drawings to describe the present invention in detail.

[0057] In an embodiment of the present application, a method for detecting brazing defects by water-immersion ultrasonic C-scan with a refracted wave perpendicular to the brazing surface is as follows:

[0058] Obtain the scanning points on the brazing surface;

[0059] Based on the constraint condition that the refracted wave is perpendicular to the scanning points of the brazed part to be measured, calculate the incident points on the incident surface and the unit vector of the incident wave direction corresponding to each scanning point, and calculate the detection trajectory of the immersion ultrasonic testing equipment according to the incident points and the unit vector of the incident wave direction.

[0060] Perform ultrasonic C-scan testing on the brazed part to be measured according to the detection trajectory, and use the obtained ultrasonic C-scan image of the brazing surface to realize the defect detection of the brazed part to be measured.

[0061] In this embodiment, by establishing the constraint condition that the refracted wave is perpendicular to the brazed part to be measured, the detection trajectory of the immersion ultrasonic testing equipment is calculated, so that after the sound beam obliquely enters the brazed part on the incident surface, its refracted longitudinal wave can be perpendicular to the scanning point of the brazing surface. When there is a brazing defect, reflection will occur and a defect echo will be generated, ensuring the effective acquisition of the brazing defect echo.

[0062] In another embodiment of the present application, for each scanning point, based on the propagation distance of the refracted wave and / or the incident angle of the corresponding incident wave, obtain a gain compensation value and perform gain compensation on the ultrasonic test result.

[0063] This embodiment performs distance and / or angle gain compensation on each scanning point, making the defect detection sensitivity of each scanning point consistent, thereby improving the detection accuracy of ultrasonic C for brazing defects.

[0064] In another embodiment of the present application, the way to obtain the gain compensation value is: according to the echo amplitude values corresponding to different propagation distances of the refracted wave and different incident angles, determine the amplitude attenuation curve, and calculate the gain compensation value at each incident point according to the amplitude attenuation curve. The amplitude attenuation curve is obtained by an independent test method using a test block with the same material as the brazed part to be measured.

[0065] This embodiment only needs to measure a test block with the same material as the brazed part once and store the measured amplitude attenuation curve. Therefore, for the same material, only one measurement is required, and the measured amplitude attenuation curve can be used multiple times.

[0066] Next, in combination with specific examples, the method for detecting brazing defects by immersion ultrasonic C with the refracted wave perpendicular to the brazing surface provided in the above embodiments will be specifically described.

[0067] This example takes the upper cover plate of the impeller as a sample model of the brazed part to be measured, and provides a method for detecting brazing defects by immersion ultrasonic C with the refracted wave perpendicular to the brazing surface. See Appendix Figure 1 and 2, the smooth surface of the upper cover plate of the impeller is the outer surface 1, and the surface with the bottom ribs 2 is the inner surface 3. There are four bottom ribs, and each bottom rib is processed with a flat-bottom blind hole; during the detection process, the outer surface 1 serves as the incident surface of ultrasonic waves, the inner surface 3 serves as the brazing surface, the bottom ribs are used to simulate the brazing positions, and the flat-bottom blind holes are used to simulate brazing defects; the specific steps of the method for detecting brazing defects with the refracted wave perpendicular to the brazing surface are as follows:

[0068] Step 1, refer to Appendix Figure 1 and 2 , obtain the contour information of the inner surface 3 (brazing surface) from the three-dimensional model of the upper cover plate of the impeller, discretize the brazing surface at equal intervals, and obtain the information of each scanning point on the brazing surface, including the coordinates of the scanning points and the unit normal vector of the scanning points. The specific implementation process of this step is as follows:

[0069] Step 1-1, extract the contour information of the inner surface 3 (brazing surface) in the engineering drawing of the brazed part to be measured, select the Cartesian coordinate system as the workpiece coordinate system, and obtain the contour analytical formula of the brazing surface as B(x B , y B , z B );

[0070] Step 1-2, discretize each point on the brazing surface to obtain the coordinates of each scanning point, denoted as Obtain the unit normal vector of each scanning point, denoted as

[0071] Step 2, refer to Appendix Figure 1 and 2 , extract the contour information of the outer surface 1 (incident surface) in the engineering drawing of the brazed part to be measured, and calculate each incident point, the unit vector of the incident wave direction and the incident angle corresponding to each incident point according to the contour information of the incident surface, the unit normal vector of each scanning point on the brazing surface obtained in Step 1 and Snell's law. The specific implementation process of this step is as follows:

[0072] Step 2-1: Extract the contour information of the outer surface 1 (incident surface) in the engineering drawing of the brazed part to be measured, select the same Cartesian workpiece coordinate system as in Step 1, and obtain the contour analytical formula of the incident surface as A(x A , y A , z A );

[0073] Step 2-2, refer to Appendix Figure 3 , based on the constraint condition that the refracted wave is perpendicular to the scanning points of the brazed part to be measured, the refracted wave is incident perpendicular to the brazing surface, and its echo is also perpendicular to the brazing surface. Therefore, the unit normal vector of each scanning point obtained in Step 1 is the unit vector of the echo direction; according to the coordinates of each scanning point on the brazing surface Unit vector of echo direction and the analytical formula A(x A , y A , z A ) of the incident surface profile, for any scanning point on the brazing surface, establish a system of equations to solve for the corresponding incident point on the incident surface:

[0074]

[0075] Solve the system of equations to obtain the corresponding incident points on the incident surface

[0076] Step 2-3, through the analytical formula A(x A , y A , z A ) of the incident surface profile, obtain the normal vectors corresponding to each incident point , denoted as

[0077] Calculate the corresponding refraction angles of each incident point according to Snell's law

[0078]

[0079] Let the unit vector function of the incident wave direction be n P (u P , v P , w P ), the incident angle function θ I , and establish a system of equations according to the refraction angle and Snell's law:

[0080]

[0081] where c1 represents the propagation speed of sound waves in water, and c2 represents the propagation speed of sound waves inside the sample model

[0082] Solve the system of equations to obtain the corresponding incident angles and the unit vector of the incident wave direction for each incident point

[0083] Step three, based on the incident points and the unit vectors of the incident wave direction corresponding to each scanning point on the brazing surface calculated in step two, calculate the probe position coordinates where the refracted wave is incident perpendicular to the brazing surface according to the set water path of the probe design, generate the probe position and direction trajectory, and convert the probe position and direction trajectory into an ultrasonic detection trajectory that can be executed by the ultrasonic device. The specific implementation process of this step is as follows:

[0084] Step 3-1, obtain the probe position coordinates corresponding to each incident point

[0085]

[0086] Among them, d w is the water path designed for the probe;

[0087] Connect the positions of each probe to generate a probe trajectory curve, see Appendix Figure 5 ;

[0088] Step 3-2: Combine the positions of each group of probes and their corresponding probe incident direction vectors (i.e., the unit vector of the incident wave direction) to generate a probe position and direction trajectory.

[0089] Step 3-3: Convert the probe position and direction trajectory into an ultrasonic detection trajectory that can be executed by the ultrasonic device.

[0090] In specific implementation, the ultrasonic detection device can adopt the method of mechanically gripping the probe or directly adopt an ultrasonic scanning device with 5 axes or more. In this embodiment, the method of mechanically gripping the probe is adopted. Therefore, the probe position and direction trajectory are converted into an ultrasonic detection trajectory that can be executed by the manipulator. The specific process is as follows:

[0091] For each incident point the unit vector of the corresponding probe incident direction is Let the unit vector of the corresponding probe scanning direction be the unit vector of the corresponding indexing direction be

[0092] Select the workpiece attitude as

[0093] a coordinate system with the end effector of the manipulator as the origin: the probe incident direction is the z direction, the probe scanning direction is the x direction, and the indexing direction is the y direction;

[0094] At this time, the rotation matrix of the end effector relative to the origin of the workpiece coordinate system is

[0095]

[0096] Since the common end effector pose of the manipulator is a fixed X-Y-Z angle coordinate system, it is necessary to convert the incident direction unit vector into the rotation angle α, the pitch angle β, and the yaw angle γ. The relationship is as follows:

[0097]

[0098] Among them, c is the cosine function cos, and s is the sine function sin;

[0099] Then

[0100]

[0101] Among them, Atan 2 is the arctangent function with two arguments;

[0102] Calculate the position information of the end trajectory of the manipulator

[0103] Finally, simulate the obtained end trajectory of the manipulator through the manipulator simulation software, eliminate dangerous factors such as singular points and interferences, and form the final ultrasonic detection trajectory for the complex surface workpiece.

[0104] Even for a large number of incident points and their corresponding different incident angles and incident direction vectors, the ultrasonic detection trajectory can be generated through the above calculations, enabling the manipulator or ultrasonic detection equipment with 5-axis linkage or above to execute the ultrasonic detection trajectory for automatic detection, thus facilitating manual operation.

[0105] Step 4: According to the incident angle θ corresponding to each incident point obtained in Step 2 Ii and the propagation distance of the refracted wave, perform gain compensation on the ultrasonic detection result. The specific implementation process of this step is as follows:

[0106] Conduct independent tests using a test block made of the same material as the sample model, change the incident angle of the incident wave and the propagation distance of the refracted wave in the test block, collect and record the amplitude of the echo signal; plot the amplitude attenuation curve with the incident angle as the abscissa and the amplitude of the echo signal as the ordinate, denoted as f(S g , θ g ), where S g is the propagation distance in the test block, and θ g is the incident angle of ultrasonic wave C on the incident surface of the test block. Based on the obtained amplitude attenuation curves f(S g , θ g ) corresponding to different propagation distances of the refracted wave and different incident angles, perform echo gain compensation. See Appendix Figure 6 , which are the amplitude attenuation curves with the values of S g being 20mm, 40mm, 50mm, and 60mm respectively.

[0107] In this embodiment, the specific process of performing echo gain compensation using the amplitude attenuation curve f(S g , θ g ) is as follows:

[0108] According to the propagation distance S in the sample model corresponding to the incidence at the incident point i of the ultrasonic wave in the sample model and the incident angle at the amplitude attenuation curve f(S g , θg ) Obtain the incident point The amplitude of the echo signal corresponding to the position

[0109] Use the difference method to obtain the ultrasonic energy attenuation value

[0110] Each incident point The corresponding gain compensation value in dB i Obtained by the following formula:

[0111]

[0112] Calculate the gain compensation value in dB corresponding to each incident point The corresponding gain compensation value in dB i When using the gain compensation value for ultrasonic testing of the refracted wave perpendicular to the brazing surface, the echo sensitivity at different incident angles can be made the same.

[0113] See Appendix Figure 7 In the table, the positions, incident angles of the incident points on the incident surface of the sample model, the propagation distances in the sample model, and the gain compensation values are recorded, so that when performing ultrasonic testing of the refracted wave perpendicular to the brazing surface on the sample model, the echo sensitivity at different incident angles is the same.

[0114] Step Five: Use a robotic ultrasonic scanning device or an ultrasonic scanning device with 5 axes or more to perform immersion ultrasonic testing on the brazed part to be tested;

[0115] (1) The ultrasonic wave is incident perpendicular to the incident surface of the sample model to obtain an ultrasonic C-scan image of the brazing surface. See Figure 8 ;

[0116] (2) According to the ultrasonic detection trajectory obtained in Step Three, perform ultrasonic testing with the refracted wave perpendicular to the brazing surface to obtain an ultrasonic C-scan image of the brazing surface. See Figure 9 ;

[0117] (3) Use the ultrasonic detection trajectory obtained in Step Four and the gain compensation value obtained in Step Four to perform ultrasonic testing with the refracted wave perpendicular to the brazing surface to obtain an ultrasonic C-scan image of the brazing surface. See Figure 10 ;

[0118] After comparison, use the ultrasonic detection trajectory obtained in Step Three and the gain compensation value obtained in Step Four to perform ultrasonic testing for brazing defects. The obtained ultrasonic image has clear brazing boundaries and prefabricated defects, and is suitable for the detection of brazed components with complex structures.

[0119] Working principle:

[0120] Principle of brazing defect detection: This method uses the three-dimensional model of the upper cover plate of the impeller to obtain the brazing surface and the outer surface contour. By using contour vector calculation and Snell's law calculation, the incident point and incident angle of the outer surface corresponding to each scanning point on the brazing surface are obtained, so that after the sound beam obliquely enters the brazed part at this point, the refracted longitudinal wave can be perpendicular to the scanning point of the brazing surface. When there are brazing defects, reflection will occur and defect echoes will be generated, realizing the effective detection of brazing defects;

[0121] Principle of gain compensation: When both the inner and outer surfaces are curved surfaces, the incident angles of the outer surface corresponding to each scanning point are different, resulting in a large difference in the energy of the refracted waves. To make the defect detection sensitivity consistent for each scanning point, while the refracted wave obliquely incident through the outer surface is perpendicular to the brazing surface, angle gain compensation is performed on each scanning point to overcome the sensitivity difference of each scanning point introduced by the oblique incidence of the outer surface;

[0122] Through the above two measures, a C-scan image with consistent sensitivity and the refracted wave perpendicular to the brazing surface is obtained, realizing the detection of brazing defects in brazed components with complex geometric shapes.

[0123] In summary, the above is only a preferred embodiment of the present invention and is not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for detecting brazing defects by water immersion ultrasonic C with the refracted wave perpendicular to the brazing surface, characterized in that, The specific process of the method for detecting brazing defects is as follows: Step 1: Obtain the brazing surface contour information from the three-dimensional model of the brazed part to be measured, discretize the brazing surface at equal intervals, and obtain the information of each scanning point on the brazing surface; Step 2: Extract the contour information of the incident surface of the brazed part to be measured. Based on the constraint condition that the refracted wave is perpendicular to the scanning points of the brazed part to be measured, calculate each incident point and the unit vector of the incident wave direction corresponding to each incident point according to the information of each scanning point on the brazing surface, the contour information of the incident surface, and Snell's law obtained in Step 1; Step 3: From the incident points and the unit vectors of the incident wave directions corresponding to each scanning point on the brazing surface calculated in Step 2, calculate the probe position coordinates where the refracted wave is incident perpendicular to the brazing surface according to the set water path of the probe design, generate the probe position and direction trajectory, and convert the probe position and direction trajectory into an ultrasonic detection trajectory that can be executed by the ultrasonic device; Step 4: Perform ultrasonic C-scan detection on the brazed part to be measured according to the detection trajectory obtained in Step 3, and use the obtained ultrasonic C-scan image of the brazing surface to realize the defect detection of the brazed part to be measured.

2. The method for detecting brazing defects by water immersion ultrasonic C of a refracted wave perpendicular to a brazing surface according to claim 1, characterized in that, For each scanning point in Step 1, based on the propagation distance of the refracted wave and / or the incident angle of the corresponding incident wave, obtain the gain compensation value and perform gain compensation on the ultrasonic detection result.

3. The method for detecting brazing defects by water immersion ultrasonic C for a refracted wave perpendicular to the brazing surface according to claim 2, characterized in that, The gain compensation value is obtained by determining the amplitude attenuation curve according to the echo amplitude sizes corresponding to different refracted wave propagation distances and different incident angles, and calculating the gain compensation value at each incident point according to the amplitude attenuation curve; The amplitude attenuation curve is obtained by means of independent tests using a test block made of the same material as the brazed part to be measured.

4. The method for detecting brazing defects by water immersion ultrasonic C of a refracted wave perpendicular to the brazing surface according to claim 3, characterized in that, The method for obtaining the amplitude attenuation curve is as follows: Perform independent tests using a test block made of the same material as the brazed part to be measured, change the incident angle of the incident wave and the propagation distance of the refracted wave in the test block, collect and record the echo signal amplitudes; draw the amplitude attenuation curve with the incident angle as the abscissa and the echo signal amplitude as the ordinate.

5. The method for detecting brazing defects by water immersion ultrasonic C for a refracted wave perpendicular to the brazing surface according to claim 1, characterized in that, In Step 1, the information of each scanning point on the brazing surface includes the scanning point coordinates and the unit normal vector of the scanning point. The specific steps of Step 1 are as follows: Extract the contour information of the brazing surface of the brazed part to be measured, select the Cartesian coordinate system as the workpiece coordinate system, and obtain the contour analytical formula of the brazing surface; discretize each point on the brazing surface according to the contour analytical formula of the brazing surface to obtain the coordinates of each scanning point, and obtain the unit normal vector of each scanning point.

6. The method for detecting brazing defects by water immersion ultrasonic C of a refracted wave perpendicular to the brazing surface according to claim 5, characterized in that, The specific steps of Step 2 are as follows: Step 2-1: Extract the contour information of the incident surface of the brazed part to be measured, and select the same Cartesian workpiece coordinate system as in Step 1 to obtain the contour analytical formula of the incident surface; Step 2-2: Based on the constraint condition that the refracted wave is perpendicular to the scanning points of the brazed part to be measured, for any scanning point on the brazing surface, obtain the corresponding incident point on the incident surface according to the coordinates of each scanning point on the brazing surface, the unit vector of the echo direction, and the contour analytical formula of the incident surface; Step 2-3: Obtain the normal vectors corresponding to each incident point through the analytical formula of the incident surface profile, and calculate the refraction angles corresponding to each incident point according to Snell's law; according to the normal vectors corresponding to each incident point and the refraction angles corresponding to each incident point, calculate the incident angles and incident wave direction unit vectors corresponding to each incident point through Snell's law.

7. The method for detecting brazing defects by water immersion ultrasonic C of a refracted wave perpendicular to a brazing surface according to claim 6, wherein, The specific steps of the third step are as follows: Step 3-1: Calculate the probe position coordinates corresponding to each incident point based on the coordinates of each incident point, the probe incident direction vector, and the designed water path of the probe. Step 3-2: Generate the probe position and direction trajectory by combining each set of probe position coordinates and its corresponding probe incident direction vector set. Step 3-3: Convert the probe position and direction trajectory into an ultrasonic detection trajectory that the ultrasonic device can execute.

8. The method for detecting brazing defects by water immersion ultrasonic C for a refracted wave perpendicular to the brazing surface according to claim 7, characterized in that, The steps of converting the probe position and direction trajectory into an ultrasonic detection trajectory that the manipulator can execute by using the manipulator to hold the probe in the ultrasonic device are as follows: Select the posture of the workpiece. According to the unit vectors of the probe incident direction, the scanning direction, and the indexing direction corresponding to each incident point, for the coordinate system with the end effector of the manipulator as the origin, the probe incident direction is the z direction, the probe scanning direction is the x direction, and the indexing direction is the y direction, obtain the rotation matrix of the end effector of the manipulator relative to the origin of the workpiece coordinate system. Then, according to the rotation matrix, convert the pose of the end effector of the manipulator into a pose with a turning angle, a pitching angle, and a yaw angle in the fixed X-Y-Z angular coordinate system, so as to obtain the position information of the end effector trajectory of the manipulator. Finally, simulate the obtained end effector trajectory of the manipulator through the manipulator simulation software to eliminate singularities and interferences, and form the final ultrasonic detection trajectory for the complex surface workpiece.

9. The method for detecting brazing defects by water immersion ultrasonic C of a refracted wave perpendicular to the brazing surface according to any one of claims 6-8, characterized in that, According to the incident angles corresponding to each incident point obtained in Step 2, design the echo gain compensation value according to the amplitude attenuation curve. The specific implementation process of this step is as follows: Obtain the echo signal amplitude corresponding to the incident point in the amplitude attenuation curve according to the propagation distance and incident angle of the ultrasonic wave at the incident point of the brazing joint to be measured in the brazing joint to be measured. Use the difference method to obtain the ultrasonic energy attenuation value. Gain compensation value db corresponding to each incident point i Obtained by the following formula: (db i ) = 20 log(100 / (ultrasonic energy attenuation value)) to calculate the gain compensation value db at the incident surface i .

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