Bogie welding seam eddy current detection equipment and detection method

Abstract

The invention belongs to the field of nondestructive testing, and particularly relates to bogie weld seam eddy current testing equipment and a testing method. The bogie weld seam eddy current testing equipment comprises a bogie, a robot, a sky rail, a displacement device and a quality inspection tool; the robot is installed on the sky rail through the robot sky rail sliding block and can move in the length direction of the bogie, and the robot clamps the quality inspection tool to conduct quality inspection on the welding seam surface and the near surface of the bogie. According to the eddy current detection system, automatic operation can be achieved, the detection performance is reliable, the detection efficiency is improved, and meanwhile the requirement for the number of quality inspection workers is lowered.

Description

Technical Field

[0001] The present invention belongs to the field of non-destructive testing for bogie welding, and particularly relates to an eddy current testing device and method for bogie welds. Background Art

[0002] The bogie is a key component of the running gear of railway vehicles, bearing the weight of the car body and the cyclic load caused by track vibration. Its fatigue resistance directly affects the driving safety of the train. The welded bogie has a large stiffness, a large number of welds and a complex distribution. Most of the main load-bearing welds are T-shaped fillet welds, such as the weld between the vertical plate and the cover plate of the bogie side beam, the weld between the cross beam sleeve and the vertical plate of the side beam, the weld between the positioning seat and the cover plate of the side beam, etc. Generally, the fatigue strength of fillet welds is much lower than that of corresponding butt welds. For full-penetration T-shaped fillet welds, fatigue failure generally initiates at the weld toe of the joint. Residual stress and deformation are likely to occur at the position of the bogie weld, which has a very adverse impact on the fracture characteristics, fatigue strength, accuracy and stability of the shape and size of the bogie.

[0003] Eddy current testing refers to a non-destructive testing method that uses the principle of electromagnetic induction to non-destructively evaluate certain properties of conductive materials and their workpieces or detect defects by measuring the changes in the induced eddy currents in the workpiece to be inspected, and occupies an important position in the field of non-destructive testing technology.

[0004] Existing bogie weld testing equipment lacks advanced core technologies and has low detection sensitivity:

[0005] First, the testing of some important parts still uses traditional manual methods. Even with the help of relevant equipment, it is difficult to effectively enhance the convenience of testing-related operations, and the missed detection rate cannot be significantly reduced.

[0006] Second, it has high requirements for the surface smoothness of the workpiece to be inspected, the technology and experience of the inspectors, has a small detection range and a slow speed, and often only conducts testing for a specific link, making it difficult to effectively improve the efficiency of testing-related operations.

[0007] Third, it uses the human eye to view or a gauge to simply take point measurements, lacking the authenticity and integrity of the surface data of the entire weld, and making it difficult to effectively enhance the accuracy of testing-related operations.

[0008] Fourth, using the principle of magnetic flux leakage generated by ferromagnetic materials at the surface and near-surface defects of the workpiece has certain limitations, such as only being applicable to ferromagnetic materials, the sensitivity during testing has a great relationship with the magnetization direction, and being affected by the workpiece surface coating, etc.

[0009] In summary, in order to improve the detection accuracy and efficiency, reduce labor consumption, and at the same time reduce the harm of magnetic particle testing to human safety, there is a great demand for non-destructive testing technology in bogie testing. Summary of the Invention

[0010] The object of the present invention is to provide an eddy current detection device for bogie welds, which mainly includes a bearing unit, a detection unit, a machine vision positioning device, a probe assembly, and a control and data processing unit, to solve the problems involved in the above-mentioned detection of railway vehicle bogies, and has the advantages of high detection sensitivity, low missed detection rate, and good convenience, and is suitable for intelligent detection of flat straight welds, corner welds, circumferential welds, etc. of bogies.

[0011] The object of the present invention is achieved by the following technical solutions:

[0012] An eddy current detection device for bogie welds includes a bogie 1, a robot 8, an overhead rail 9, a position-changing device, and a quality inspection tooling 11; the robot 8 is slidably connected to the overhead rail 9, the overhead rail 9 is parallel to the length direction of the bogie 1, the robot 8 can move along the length direction of the bogie 1, and the robot 8 clamps the quality inspection tooling 11 to perform surface and near-surface quality detection on the welds of the bogie 1; the bogie 1 is fixedly connected to the position-changing device, and the position-changing device drives the bogie to move in three directions of X, Y, and Z.

[0013] As a more optimal technical solution of the present invention, the position-changing device includes a fixed frame platform 2, a bearing unit, and a ground rail. The bearing unit includes a main bearing unit 3 and a secondary bearing unit 4. The main bearing unit 3 and the secondary bearing unit 4 are respectively fixedly connected to the front and rear ends of the fixed frame platform 2. The bogie 1 is fixedly connected to the fixed frame platform 2. The ground rail includes a main bearing ground rail 5 and a secondary bearing ground rail 6. The main bearing unit 3 is slidably connected to the main bearing ground rail 5, and the secondary bearing unit 4 is slidably connected to the secondary bearing ground rail 6.

[0014] As a more optimal technical solution of the present invention, the bearing unit includes a turntable and a mounting seat. A Y-direction track is provided on the mounting seat. The fixed frame platform 2 is fixedly connected to the eccentric position of the turntable. The turntable is slidably connected in the Y-direction track. The eccentric structure can better carry the bogie 1, and the rotation pose of the bogie 1 has no constraint, realizing full-coverage detection of welds, and improving the detection efficiency. The turntable is driven by a gear or a motor to lift and rotate, thereby driving the bogie 1 to lift and rotate arbitrarily. The fixed frame platform 2 facilitates the loading of the bogie 1, and at the same time keeps a safe distance from the ground when the bogie 1 rotates 360° to prevent touching the ground. The supporting hand on the turntable can adapt to the installation requirements of different types of bogies. On the one hand, the ground rail can make the bearing unit move to adapt to the installation requirements of different types of bogies, and on the other hand, it locks the position of the bearing unit to prevent the bogie from causing the bearing unit to move backward due to its own weight.

[0015] As a more preferable technical solution of the present invention, the quality inspection tooling 11 includes a probe tooling 12 for eddy current testing, a probe holder 16, and a CCD vision camera 14. The probe tooling 12 includes an XYZ three-axis electric slide rail mechanism 17 and an eddy current flaw detection mechanism 18. The eddy current flaw detection mechanism 18 is fixedly connected to the slide rail mechanism 17. The slide rail mechanism 17 and the CCD vision camera 14 are fixedly connected to both sides of the probe holder 16, and the probe holder 16 is fixedly connected to the robot 8. The eddy current flaw detection mechanism 18 is used to detect groove welds, fillet welds, and circumferential welds. When detecting groove welds, it scans along both sides of the weld respectively. When detecting fillet welds, it first scans the front of the fillet weld, and then uses the XYZ three-axis electric slide rail mechanism 17 to adjust the angle and scan along the side wall of the fillet weld. The CCD vision camera 14 monitors the scanning state of the eddy current flaw detection mechanism 18 detecting the weld and scans the weld to obtain several feature points on the weld image. The eddy current flaw detection mechanism 18 realizes translational movement on the XYZ three axes through the slide rail mechanism 17 to achieve refined detection.

[0016] As a more preferable technical solution of the present invention, the probe holder 16 includes a flange 19 and a connecting frame 20. The quality inspection tooling 11 is fixedly connected to the end of the robot 8 through the flange 19 on the probe holder 16.

[0017] As a more preferable technical solution of the present invention, the slide rail mechanism 17 includes an X-axis slide rail 21, a Y-axis slide rail 22, and a Z-axis slide rail 23 which are arranged in the XYZ directions and fixedly connected as a whole.

[0018] As a more preferable technical solution of the present invention, the eddy current flaw detection mechanism 18 includes a laser sensor 24 and an eddy current flaw detection head 25. The laser sensor 24 projects a laser projection line onto the weld of the bogie 1. The CCD vision camera 14 collects the pictures with the laser line, extracts the feature points of each frame of the image after processing, and transmits them to the controller to control the robot 8. The robot 8 drives the trajectory of the eddy current detection probe tooling 12 to detect the weld.

[0019] Another object of the present invention is to provide a bogie weld eddy current detection method based on the above detection equipment, including the following steps:

[0020] Step 1: Install the bogie 1 on the fixed mount 2, and the positioning device lifts the bogie 1 to the specified height;

[0021] Step 2: Determine the weld to be detected;

[0022] Step 3: Use the CCD vision camera 14 and the laser sensor 24 to scan the weld to be detected frame by frame. After the weld image is preprocessed and the center line is extracted, the weld geometric contour morphology characterized by the center line is obtained; the laser light plane is parallel to the weld cross-section, and the laser center line is located on the angular bisecting plane of the weld base metal plane;

[0023] Step 4: Extract the feature points of each frame of image, which are A, D, C, and B in sequence. Points A and B are the two end points of the weld geometric profile, and points C and D are the intersection points of the weld bulge and the plane. The lengths of line segments AD and CB are equal to the diameter of the eddy current testing head 25. Assume that the line where point A is located is the X-axis and the weld length direction is the Y-axis, and establish a three-dimensional coordinate system of the bogie 1. Determine the plane where the workpiece is located by using point A1 and point B1 in the first frame of image and point A2 in the second frame of image.

[0024] Step 5: Obtain the detection angle of the eddy current detection probe tooling 12:

[0025] Step 5.1: Determine the coordinates of the midpoint E of line segment AD and the midpoint F of line segment BC. Move the eddy current detection probe tooling 12 to points E and F, and the detection angles at the two points are perpendicular to the workpiece plane and are 90°.

[0026] Step 5.2: Obtain the curve equations of D, Q, and C. Use numerous points among them for polynomial fitting to determine the curve equations, and take the derivative of the normal line thereof to determine the angles at each scanned point.

[0027] Step 5.3: Use integration to obtain the weld arc length L. Name the trajectory fitted by point E in each frame of image as trajectory L1, name the trajectory fitted by point F in each frame of image as trajectory L2, and at the same time divide the DC curve into equal parts, and name the trajectories fitted by the midpoints of each equal part as trajectories L3, L4...L n ;

[0028] Step 5.4: Obtain the normal slope at a certain point on the curve to determine the angles at each scanned point and determine the angles at the scanned trajectories.

[0029] Step 6: Plan the detection trajectory of the eddy current detection probe tooling 12:

[0030] Transform the coordinates of points E and F in each frame of image and the midpoints of each segment of the weld arc under the bogie coordinate system into three-dimensional coordinates under the robot base coordinate system, and perform quasi-uniform cubic B-spline curve fitting on the coordinates of points E and F in each frame of image and the midpoints of each segment of the weld arc respectively to obtain the grinding trajectory curves L1, L2, L3, L4...L n ;

[0031] Step 7: Detect the front and back welds of the bogie according to the planned detection trajectory:

[0032] According to the completed detection angles and detection trajectories, the robot 8 drives the eddy current detection probe tooling 12 to be positioned on the bogie 1 and sequentially detects the welds to be inspected on the front and back of the bogie.

[0033] As a better technical solution of the present invention, the specific steps for obtaining the detection angle of the eddy current detection probe tooling 12 in step 5 are as follows:

[0034] Step 5.2.1: Construct a polynomial model:

[0035] Given an order of 2, the polynomial model can be expressed as:

[0036] f(x) = a2x 2 + a1x + a0

[0037] where a2 and a1 are coefficients to be solved.

[0038] Step 5.2.2: Define the error metric:

[0039] Use the mean square error (MSE) as the error metric:

[0040]

[0041] where m is the number of data points, and (x i , y i ) is a given data point. To minimize the MSE, we can take its partial derivative with respect to each coefficient a i (i = 0, 1,..., m), set the partial derivative to 0, use a system of linear equations to express the value of the polynomial f(x) at each data point x as a linear combination of the coefficients a i and solve this system of linear equations to find the coefficients that minimize the MSE;

[0042] Step 5.2.3: Use stepwise regression technology to evaluate the fitting effect and determine the polynomial order:

[0043] Starting from a second-order polynomial, gradually increase the order, and evaluate the performance of the model at each step and repeat steps 5.2.1 to 5.2.3. When increasing the order no longer significantly improves the model performance, stop increasing the order. Evaluate the fitting effect by the size of the coefficient of determination R 2 , and the formula for the coefficient of determination R 2 is:

[0044]

[0045] Step 5.2.4: Determine the polynomial curve equation:

[0046] Determine the fitted polynomial curve equation as:

[0047] f(x) = a m x m + a m-1 x m-1 +... + a1x + a0

[0048] As a more optimal technical solution of the present invention, the specific steps for planning the detection trajectory of the eddy current detection probe tooling 12 in step 6 are as follows:

[0049] Step 6.1: Define the basic coordinate system as [B], the gantry coordinate system [G], the robot base coordinate system [MB], the probe holder coordinate system [MH], the head tooling 1 coordinate system [T], the positioner coordinate system [P], and the bogie coordinate system [BG].

[0050] Step 6.2: Describe the pose of the eddy current detection probe tooling 12:

[0051] The position of the robot 8 refers to the vector change of the position of the eddy current detection probe tooling 12 relative to the origin of the basic coordinate system in the basic coordinate system. Then, the position point P of the eddy current detection probe tooling 12 can be described as B P.

[0052]

[0053] The pose of the eddy current detection probe tooling 12 can be expressed as that the basic coordinate system X - Y - Z undergoes three coordinate rotations to become a new coordinate system U - V - W, where U, V, and W are the three coordinate axes of the eddy current detection probe tooling 1 coordinate system. Then, the rotation matrix R is obtained as:

[0054]

[0055] Express the rotation matrix R in terms of the yaw angle γ, pitch angle β, and roll angle α. The rotation matrix R in the new expression is:

[0056] R xyz = R x (α)R y (β)R z (γ)

[0057]

[0058] Combining the above pose and position descriptions, the pose of the eddy current detection probe tooling 1 coordinate system is obtained as:

[0059]

[0060] Convert the matrix [T] into a transformation matrix from [B] to [T] Obtain:

[0061]

[0062]

[0063] Step 6.3. Pose description of the trajectory points in the base coordinate system [MB] of the six-axis robot:

[0064] Define as the transformation matrix from the base coordinate system to the gantry coordinate system, as the transformation matrix from the gantry coordinate system to the base coordinate system of the six-axis robot, as the transformation matrix from the coordinate system of the probe gripper 1 of the six-axis robot to the base coordinate system of the six-axis robot, as the transformation matrix from the coordinate system of the eddy current testing probe tooling 1 to the coordinate system of the probe gripper 1 of the six-axis robot, as the transformation matrix from the coordinate system of the positioner to the base coordinate system, as the transformation matrix from the bogie coordinate system to the coordinate system of the positioner;

[0065] The trajectory points in the bogie coordinate system are represented in the base coordinate system of the six-axis robot as Obtained from the calculation formula:

[0066]

[0067]

[0068] During the detection process, the probe tooling 12 contacts the bogie 1. At this time, the pose of the trajectory to be detected on the surface of the bogie 1 is equivalent to that of the eddy current testing probe tooling 12, that is Similarly, the pose description of the midpoint of each segment in the weld arc in the base coordinate system [MB] of the six-axis robot is obtained;

[0069] Step 6.4. Determine the detection trajectory:

[0070] Perform quasi-uniform cubic B-spline curve fitting on the coordinates of point E in each frame of the image to obtain the detection trajectory curve L1. Perform quasi-uniform cubic B-spline curve fitting on the coordinates of point F in each frame of the image to obtain the detection trajectory curve L2. Perform quasi-uniform cubic B-spline curve fitting on the coordinates of the midpoint of each segment in the weld arc in each frame of the image to obtain the detection trajectory curves L3, L4... L n .

[0071] The beneficial effects are as follows:

[0072] The intelligent eddy current testing equipment and method for bogies provided by the present invention improve the detection accuracy and efficiency for the detection of high-speed train bogies, reduce the labor consumption, while reducing the harm to human safety caused by magnetic particle testing in the past, and the detection accuracy is much higher than that of portable eddy current flaw detectors, meeting the requirements of high-speed vehicle detection for non-destructive testing technology.

[0073] The bogie intelligent eddy current detection equipment and method provided by the present invention can automatically scan the bogie welds, extract image feature points, and can independently transform the coordinates of the feature points by using the Euler angle coordinate system transformation method, so as to plan the detection trajectory. The accurate trajectory planning makes up for the blank of low-energy cancellation in intelligent eddy current detection, automatically completes the quality inspection process, and realizes the complete acquisition, analysis and recording of the weld surface information and the near-surface quality information of the weld. BRIEF DESCRIPTION OF THE DRAWINGS

[0074] The drawings described herein are used to provide a further understanding of the present invention, and constitute a part of this application. The schematic examples and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation of the present invention.

[0075] Figure 1 It is a schematic structural diagram of the bogie weld eddy current detection equipment of the present invention.

[0076] Figure 2 It is a schematic structural diagram of the weld quality inspection tooling of the present invention.

[0077] Figure 3 It is a schematic structural diagram of the probe holder and the connecting plates on both sides of the present invention.

[0078] Figure 4 It is a schematic diagram of the weld mark to be detected on the front of the bogie of the present invention (the red line is the weld).

[0079] Figure 5 It is a schematic diagram of the weld mark to be detected on the back of the bogie of the present invention (the red line is the weld).

[0080] Figure 6 It is a schematic diagram of the weld scan result.

[0081] Figure 7 It is a schematic diagram of the detection angle planning principle of the present invention.

[0082] Figure 8 It is a schematic diagram of the detection trajectory planning principle of the present invention, where M1 is the position 1 of the eddy current detection probe, M2 is the position 3 of the eddy current detection probe, M3 is the position n - 1 of the eddy current detection probe, and M4 is the position n of the eddy current detection probe.

[0083] Figure 9 It is a schematic structural diagram of the X-axis slide rail of the present invention.

[0084] Figure 10 It is a schematic structural diagram of the Y-axis slide rail of the present invention.

[0085] Figure 11 It is a schematic structural diagram of the Z-axis slide rail of the present invention.

[0086] Figure 12Schematic structural diagram of the laser sensor of the present invention.

[0087] Figure 13 Schematic structural diagram of the eddy current flaw detector head of the present invention.

[0088] In the figure: 1, bogie; 2, bogie fixing frame; 3, main load-bearing unit; 4, auxiliary load-bearing unit; 5, main load-bearing ground rail; 6, auxiliary load-bearing ground rail; 7, gantry; 8, robot; 9, overhead rail; 10, robot overhead rail slider; 11, quality inspection tooling; 12, probe tooling; 13, probe tooling connecting plate; 14, CCD vision camera; 15, camera connecting plate; 16, probe gripper; 17, slide rail mechanism; 18, eddy current flaw detection mechanism; 19, flange; 20, connecting frame; 21, X-axis slide rail; 22, Y-axis slide rail; 23, Z-axis slide rail; 24, laser sensor; 25, eddy current flaw detector head. Detailed implementation mode

[0089] The following further describes the detailed content and specific implementation mode of the present invention with reference to the accompanying drawings.

[0090] See Figures 1 to 13 As shown, the present invention provides an intelligent eddy current detection device for bogies, including a bogie 1, a robot 8, an overhead rail 9, a position-changing device, and a quality inspection tooling 11; the robot 8 is installed on the overhead rail 9 through a robot overhead rail slider 10 and can move along the length direction of the bogie 1. The robot 8 holds the quality inspection tooling 11 to perform surface quality inspection and near-surface quality inspection of the welds of the bogie 1.

[0091] In some embodiments, the position-changing device includes a fixed frame 2, a main load-bearing unit 3, an auxiliary load-bearing unit 4, a main load-bearing ground rail 5, and an auxiliary load-bearing ground rail 6. The main load-bearing unit 3 and the auxiliary load-bearing unit 4 are both fixed on the translation sliders of the load-bearing unit ground rail and can move translationally relative to the bogie 1. The turntables of the main load-bearing unit 3 and the auxiliary load-bearing unit 4 have an eccentric design, which can better carry the bogie and achieve full-coverage detection of welds in all directions, improving the detection efficiency. The bogie 1 has no pose constraint when rotating under the position-changing device. The turntable is driven by a gear and can rotate the bogie 1 arbitrarily. The turntables of the main load-bearing unit 3 and the auxiliary load-bearing unit 4 have a lifting function and are also equipped with a fixed frame 2 to facilitate the loading of the bogie 1 and prevent the bogie 1 from touching the ground when rotating 360°, maintaining a safe distance from the ground. The hand support design on the turntables of the main load-bearing unit 3 and the auxiliary load-bearing unit 4 can adapt to the installation requirements of different types of bogies. The load-bearing ground rail can enable the load-bearing unit to move, meeting the installation requirements of different types of bogies, and on the other hand, locking the position of the load-bearing unit to prevent the bogie from causing the load-bearing unit to move backward due to its own weight.

[0092] In some embodiments, one end of the bogie 1 fixed to the main load-bearing unit 3 is the A end, and one end of the bogie 1 fixed to the auxiliary load-bearing unit 4 is the B end. The A end of the bogie must be fixed to the main load-bearing unit 3, and the B end of the bogie must be fixed to the auxiliary load-bearing unit 4 to meet the requirement of improving the high efficiency of intelligent detection of the bogie 1.

[0093] In some embodiments, the quality inspection tooling 11 includes an eddy current detection probe tooling 12, an eddy current detection probe tooling connection plate 13, a CCD vision camera 14, a CCD vision camera connection plate 15, and a six-axis robot probe gripper 16. The eddy current detection probe tooling 12 includes an XYZ three-axis electric slide rail mechanism 17 and an eddy current flaw detection mechanism 18. The eddy current detection probe tooling 12 is fixed to the right side of the six-axis robot probe gripper 16 through the eddy current detection probe tooling connection plate 13. The CCD vision camera 14 is fixed to the left side of the six-axis robot probe gripper 16 through the CCD vision camera connection plate 15. The eddy current flaw detection mechanism 18 can achieve translational movement on the XYZ three axes through the XYZ three-axis electric slide rail mechanism 17 to achieve refined detection.

[0094] In some embodiments, the six-axis robot probe gripper 16 includes a flange 19 and a connecting frame 20. The entire quality inspection tooling 11 is fixed to the sixth axis of the robot 8 through the flange 19 on the six-axis robot probe gripper 16.

[0095] In some embodiments, the eddy current flaw detection mechanism 18 is used to detect groove welds, fillet welds, and circumferential welds. When detecting groove welds, it scans along both sides of the weld respectively. When detecting fillet welds, it first scans the front of the fillet weld, and then adjusts the angle along the side wall of the fillet weld by using the XYZ three-axis electric slide rail mechanism 17. The CCD vision camera 14 monitors the scanning state of the eddy current flaw detection mechanism 18 detecting the weld and scans the weld to obtain several feature points on the weld image. The XYZ three-axis electric slide rail mechanism 17 includes an X-axis electric slide rail mechanism 21, a Y-axis electric slide rail mechanism 22, and a Z-axis electric slide rail mechanism 23. The eddy current flaw detection mechanism 18 includes a laser sensor 24 and an eddy current flaw detection head 25. The laser sensor 24 projects a laser projection line onto the bogie weld. The CCD vision camera 14 collects the pictures with the laser line, extracts the feature points of each frame of the image after processing, and transmits them to the six-axis robot controller. The robot 8 controls the trajectory of the eddy current detection probe tooling 12 to detect the weld.

[0096] Refer to Figures 1 to 7 , an intelligent eddy current detection method for a bogie of the present invention includes the following steps:

[0097] Step 1, preparation work of the intelligent eddy current detection equipment for the bogie:

[0098] Move the carrying unit to a suitable position for the carrying ground rail to facilitate the upper and lowering of the bogie 1, and move the robot 8 to the leftmost end of the overhead rail 9, install the bogie 1 to be tested on the bogie fixing frame 2, start the displacement device, and lift the bogie to the specified height.

[0099] Step 2, determine the weld area to be tested: obtain the stress concentration area through actual finite element simulation, fatigue test or force analysis, and determine the weld in the fatigue weak area.

[0100] Step 3, scanning the weld and image processing: Use the CCD visual camera 14 and the laser sensor 24 to scan the weld to be detected frame by frame. During scanning, the laser light plane is parallel to the weld cross section, and the laser center line is located on the plane that divides the angle of the weld parent material plane. The weld images scanned frame by frame by the CCD visual camera 14 are sequentially transmitted to the controller of the robot 8, and are subjected to image preprocessing and center line extraction. The image preprocessing includes video frame acquisition, effective area positioning and extraction, Ostu filtering, and morphological trimming, and the geometric contour morphology of the weld represented by the center line is obtained respectively.

[0101] Step 4, extracting feature points of each frame image: assuming that the diameter of the eddy current flaw detection head 25 is d, the length of the weld is m, and the arc length of the weld is L, the two end points of the weld geometric contour are set as point A and point B respectively, and the straight line where point A on the weld geometric contour is located is used as the X-axis and the direction perpendicular to the plane where the weld geometric contour is located is used as the vertical coordinate to establish a three-dimensional coordinate system for the bogie 1, and use point A1 and point B1 in the first frame and point A2 in the second frame image to determine the plane where the workpiece is located.

[0102] First, calculate the vectors from A1 to B1 and from A1 to A2:

[0103]

[0104]

[0105] Then use the vector outer product to find the normal vector of the plane:

[0106]

[0107] Then use the point equation to represent the plane:

[0108] A(x-x1)+B(y-y1)+C(z-z1)=0

[0109] Intersect with the weld convex plane to determine the characteristic points C and D. Starting from point A, the first endpoint is point D, and starting from point B, the first endpoint is point C. AD = BC = eddy current flaw detection head 25 diameter d;

[0110] Step 5, obtaining the detection angle of the eddy current detection probe tooling 12: First, determine the midpoints of line segment AD and line segment BC, then find the curve equations of D, Q, and C, then set the scanning principle, and finally take the derivative of its normal line to determine the angles at each scanning point and the angle at the scanning trajectory. It includes the following steps:

[0111] Step 5.1, determine the midpoints of AD and BC; Step 5.2, fit a polynomial and take the derivative to determine the angles at each scanning point; Step 5.3, set the scanning principle; Step 5.4, determine the angle at the scanning trajectory; the specific steps are as follows:

[0112] Step 5.1, determine the midpoints of line segment AD and line segment BC:

[0113] The coordinates of the midpoint E of AD are:

[0114]

[0115] The coordinates of the midpoint F of BC are:

[0116]

[0117] The detection angles of the eddy current detection probe tooling 12 at points E and F are perpendicular to the workpiece plane and are 90°.

[0118] Step 5.2, fit a polynomial and determine the angles at each scanning point:

[0119] Use countless points on the D, Q, C curves to perform polynomial fitting to determine the curve equation and take the derivative of its normal line to determine the angles at each scanning point. The specific steps are as follows:

[0120] Step 5.2.1, construct a polynomial model:

[0121] Since the order directly affects the fitting accuracy and the risk of overfitting. A too low order may lead to underfitting, while a too high order may lead to overfitting. Therefore, start fitting from the second order, and then construct a polynomial model. Given the order of 2, the polynomial model can be expressed as:

[0122] f(x) = a2x 2 + a1x + a0

[0123] where a2 and a1 are the coefficients to be solved.

[0124] Step 5.2.2, define the error metric:

[0125] Use the mean squared error (MSE) as the error metric:

[0126]

[0127] where m is the number of data points, (x i, y i ) is the given data point. To minimize the MSE, we can take its partial derivative with respect to each coefficient a i (i = 0, 1, …, m), set the partial derivative to 0, and use the system of linear equations to express the value of the polynomial f(x) at each data point x as a linear combination of the coefficients a i and solve this system of linear equations to find the coefficients that minimize the MSE.

[0128] Step 5.2.3, Use the stepwise regression technique to evaluate the fitting effect and determine the polynomial order:

[0129] Starting from a second-degree polynomial, gradually increase the order, and evaluate the performance of the model at each step and repeat Steps 5.2.1 to 5.2.3. Stop increasing the order when increasing the order no longer significantly improves the model performance. Evaluate the fitting effect by the magnitude of the coefficient of determination R 2 The coefficient of determination R 2 The formula is:

[0130]

[0131] Step 5.2.4, Determine the polynomial curve equation:

[0132] Determine the fitted polynomial curve equation as:

[0133] f(x) = a m x m + a m-1 x m-1 +... + a1x + a0

[0134] Step 5.3, Set the scanning principle; first, use integration to find the weld arc length L:

[0135] y = f(x) = a m x m + a m-1 x m-1 +... + a1x + a0

[0136]

[0137] Name the trajectory fitted at point E of each frame of the image as trajectory L1, name the trajectory fitted at point F of each frame of the image as trajectory L2, and at the same time divide the DC curve into equal parts, and name the trajectory fitted at the midpoint of each equal part as trajectory L3, L4... L n .

[0138] Step 5.4, Determine the angle at the scanning trajectory:

[0139] Find the normal slope at a certain point on the curve to determine the angles at each scanning point and the angles at the scanning trajectory: Given that the curve equation is y = f(x) = a m x m + a m-1 x m-1 +... + a1x + a0. Assume that the midpoint P of a certain part is (x0, y0), and the tangent slope obtained is:

[0140] k = f′(x0)

[0141] Using k normal × k = -1, find the slope of the normal:

[0142]

[0143] Find that the detection angle of the eddy current detection probe tooling 12 at point P should be:

[0144] α P = arctank normal

[0145] Similarly, determine the detection angles α3, α4... α n at the trajectories L3, L4... L n ;

[0146] Step 6, Planning of the detection trajectory of the eddy current detection probe tooling 12: Transform the coordinates of the midpoints of each segment of E, F, and the weld arc in the bogie coordinate system in each frame of the image into the three-dimensional coordinates in the robot base coordinate system, and perform quasi-uniform cubic B-spline curve fitting on the coordinates of the midpoints of each segment of E, F, and the weld arc in each frame of the image to obtain the grinding trajectory curves L1, L2, L3, L4... L n , The specific steps are as follows:

[0147] Step 6.1, Define each coordinate system in the bogie intelligent eddy current detection equipment system:

[0148] Including the base coordinate system, the gantry coordinate system (at the center of the position of the hoisting six-axis robot), the robot base coordinate system, the eddy current detection probe tooling coordinate system, the six-axis robot probe gripper coordinate system, the positioner coordinate system, and the bogie coordinate system. Define the base coordinate system as [B], the gantry coordinate system [G], the six-axis robot base coordinate system [MB], the six-axis robot probe gripper 1 coordinate system [MH], the eddy current detection probe tooling 1 coordinate system [T], the positioner coordinate system [P], and the bogie coordinate system [BG].

[0149] Step 6.2, Describe the pose of the eddy current detection probe tooling 12:

[0150] The position of the robot 8 refers to the vector change of the position of the eddy current detection probe tooling 12 relative to the origin of the base coordinate system in the base coordinate system. Then, the position point P of the eddy current detection probe tooling 12 can be described as B P.

[0151]

[0152] The attitude of the eddy current detection probe tooling 12 can be expressed as that the base coordinate system X - Y - Z undergoes three coordinate rotations to become a new coordinate system U - V - W, where U, V, and W are the three coordinate axes of the eddy current detection probe tooling 1 coordinate system. Then, the rotation matrix R is obtained as follows:

[0153]

[0154] The rotation matrix R can already accurately describe the attitude of the eddy current detection probe tooling 1 coordinate system. To simplify the operation of inputting the expected attitude of the eddy current detection probe tooling 12, the Euler angle coordinate transformation method is used to express the rotation matrix R in terms of the roll angle γ, pitch angle β, and yaw angle α. The rotation matrix R in the new expression is:

[0155] R xyz = R x (α)R y (β)R z (γ)

[0156]

[0157] Combining the above attitude and position descriptions, the pose of the eddy current detection probe tooling 1 coordinate system can be obtained as follows:

[0158]

[0159] Convert the matrix [T] into a transformation matrix from [B] to [T] The result is:

[0160]

[0161]

[0162] Step 6.3, the pose description of the trajectory point in the six - axis robot base coordinate system [MB]:

[0163] Define as the transformation matrix from the base coordinate system to the gantry coordinate system, as the transformation matrix from the gantry coordinate system to the six - axis robot base coordinate system, as the transformation matrix from the six - axis robot probe gripper 1 coordinate system to the six - axis robot base coordinate system, is the transformation matrix from the coordinate system of the eddy current testing probe tooling 1 to the coordinate system of the six-axis robot probe gripper 1, is the transformation matrix from the coordinate system of the position-changing device to the base coordinate system, is the transformation matrix from the bogie coordinate system to the coordinate system of the position-changing device.

[0164] Finally, the trajectory point in the bogie coordinate system is represented in the base coordinate system of the six-axis robot as According to the calculation formula:

[0165]

[0166]

[0167] During the detection process, the eddy current testing probe tooling 12 contacts the bogie 1. At this time, the pose of the trajectory to be detected on the surface of the bogie 1 is equivalent to that of the eddy current testing probe tooling 12, that is

[0168] Similarly, the pose description of the midpoint of each segment in the weld arc in the base coordinate system [MB] of the six-axis robot is obtained.

[0169] Step 6.4, determine the detection trajectory:

[0170] Perform quasi-uniform cubic B-spline curve fitting on the coordinates of point E in each frame of the image to obtain the detection trajectory curve L1. Perform quasi-uniform cubic B-spline curve fitting on the coordinates of point F in each frame of the image to obtain the detection trajectory curve L2. Perform quasi-uniform cubic B-spline curve fitting on the coordinates of the midpoint of each segment in the weld arc in each frame of the image to obtain the detection trajectory curves L3, L4... L n 。

[0171] Step 7, detect the front weld of the bogie according to the planned detection trajectory: The robot 8 drives the eddy current testing probe tooling 12 to position the eddy current testing probe tooling 12 on the in-place bogie 1 according to the detection angle planned in step 5 and the detection trajectory planned in step 6, and sequentially detect the welds to be inspected.

[0172] Step 8, detect the back weld of the bogie according to the planned detection trajectory: When all the welds to be inspected on one side of the bogie 1 are detected, use the position-changing device to flip the bogie 1, and at the same time, detect the remaining welds according to the detection angle planned in step 5 and the detection trajectory planned in step 6. It is also possible to flip the bogie 1 by a certain angle according to specific requirements.

[0173] Step 9, analyze and save the detection images and data results:

[0174] Use a portable eddy current instrument or magnetic particle flaw detection method to perform composite flaw detection on the suspected defective part of the bogie 1 to further determine the equivalent and location of the suspected defect. Save the images captured by the CCD vision camera 14 and the processed data structure.

[0175] After the inspection, the next batch of bogies 1 is loaded into the bogie fixing jig 2, and surface quality inspection and near-surface quality inspection are carried out on the next batch of bogies 1 according to steps 1 to 9.

[0176] In the present invention, the "front" and "rear" are located in the length direction of the bogie.

[0177] In the present invention, unless otherwise clearly defined and limited, the terms "installation" and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; for those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0178] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0179] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A bogie weld eddy current testing device, characterized in that: It includes a bogie 1, a robot 8, a ceiling rail 9, a displacement device, and a quality inspection tool 11; the robot 8 is slidably connected to the ceiling rail 9, the ceiling rail 9 is parallel to the length direction of the bogie 1, the robot 8 can move along the length direction of the bogie 1, and the robot 8 clamps the quality inspection tool 11 to perform weld surface and near-surface quality inspection on the bogie 1; the bogie 1 is fixedly connected to the displacement device, and the displacement device drives the bogie to move and rotate.

2. The bogie weld eddy current testing equipment according to claim 1, characterized in that: The displacement device includes a fixed frame 2, a load-bearing unit and a ground rail. The load-bearing unit includes a main load-bearing unit 3 and a secondary load-bearing unit 4. The main load-bearing unit 3 and the secondary load-bearing unit 4 are respectively fixedly connected to the front and rear ends of the fixed frame 2. The bogie 1 is fixedly connected to the fixed frame 2. The ground rail includes a main load-bearing ground rail 5 and a secondary load-bearing ground rail 6. The main load-bearing unit 3 is slidably connected to the main load-bearing ground rail 5, and the secondary load-bearing unit 4 is slidably connected to the secondary load-bearing ground rail 6.

3. The bogie weld eddy current testing equipment according to claim 2, characterized in that: The bearing unit comprises a turntable and a mounting seat, a Y-track is provided on the mounting seat, a fixed stand 2 is fixedly connected to the eccentric part of the turntable, and the turntable is slidably connected in the Y-track.

4. The bogie weld eddy current testing equipment according to claim 1, characterized in that: The quality inspection tooling 11 includes a probe tooling 12 for eddy current detection, a probe holder 16 and a CCD visual camera 14. The probe tooling 12 includes an XYZ three-axis electric slide mechanism 17 and an eddy current flaw detection mechanism 18. The eddy current flaw detection mechanism 18 is fixedly connected to the slide mechanism 17. The slide mechanism 17 and the CCD visual camera 14 are fixedly connected on both sides of the probe holder 16. The probe holder 16 is fixedly connected to the robot 8.

5. The bogie weld eddy current testing equipment according to claim 4, characterized in that: The probe holder 16 includes a flange 19 and a connecting frame 20 , and the quality inspection tool 11 is fixedly connected to the end of the robot 8 via the flange 19 on the probe holder 16 .

6. The bogie weld eddy current testing equipment according to claim 4, characterized in that: The slide rail mechanism 17 comprises an X-axis slide rail 21, a Y-axis slide rail 22 and a Z-axis slide rail 23 which are arranged in the XYZ directions and fixedly connected as one.

7. The bogie weld eddy current testing equipment according to claim 4, characterized in that: The eddy current flaw detection mechanism 18 includes a laser sensor 24 and an eddy current flaw detection head 25. The laser projection line of the laser sensor 24 is projected onto the weld of the bogie 1, and the CCD visual camera 14 collects images with the laser projection line.

8. A bogie weld eddy current detection method based on the above detection equipment, characterized in that: The following steps are involved: Step 1: Install the bogie 1 on the fixed platform 2, and the displacement device lifts the bogie 1 to a specified height; Step 2: Determine the weld to be tested; Step 3, using the CCD visual camera 14 and the laser sensor 24 to scan the weld to be inspected frame by frame, and after the weld image is preprocessed and the center line is extracted, the weld geometric contour morphology represented by the center line is obtained; the laser light plane is parallel to the weld cross section, and the laser center line is located on a plane that divides the angle of the weld parent material plane equally; Step 4, extract the feature points of each frame image, which are A, D, C and B in sequence, where points A and B are the two end points of the weld geometric contour, points C and D are the intersection points of the weld bulge and the plane, and the length of line segment AD and line segment CB are equal to the diameter of the eddy current flaw detection head 25; let the straight line where point A is located be the X-axis and the weld length direction be the Y-axis, establish a three-dimensional coordinate system for the bogie 1, and use points A1 and B1 in the first frame image and point A2 in the second frame image to determine the plane where the workpiece is located; Step 5: Get the detection angle of the eddy current detection probe tooling 12: Step 5.1, determine the coordinates of the midpoint E of the line segment AD and the midpoint F of the line segment BC, move the eddy current detection probe fixture 12 to points E and F, and the detection angle at the two points is 90° perpendicular to the workpiece plane; Step 5.2, find the curve equations of D, Q, and C, use countless points to perform polynomial fitting to determine the curve equations, and take the derivative of its normal to determine the angles at each scanning point; Step 5.3, use the integral to calculate the arc length L of the weld, name the fitting trajectory of point E of each frame image as trajectory L1, name the fitting trajectory of point F of each frame image as trajectory L2, and divide the DC curve into The trajectory of the midpoint fitting of each equal part is named trajectory L3, L4...L n ; Step 5.4, calculate the normal slope at a certain point of the curve to determine the angle at each scanning point and determine the angle at the scanning trajectory; Step 6: Plan the detection trajectory of the eddy current detection probe tooling 12: The coordinates of the E and F points in each frame image and the midpoint of each segment of the weld arc in the bogie coordinate system are transformed into the three-dimensional coordinates of the robot base coordinate system, and the coordinates of the E and F points in each frame image and the midpoint of each segment of the weld arc are fitted with a quasi-uniform cubic B-spline curve to obtain the grinding trajectory curves L1, L2, L3, L4...L n ; Step 7: According to the planned detection angle and detection trajectory, the robot 8 drives the eddy current detection probe tooling 12 to be positioned on the bogie 1 to detect the welds to be inspected on the front and back of the bogie in turn.

9. The bogie weld eddy current testing method as claimed in claim 8, characterized in that: The step 5 of obtaining the detection angle of the eddy current detection probe tooling 12 specifically includes the following steps: Step 5.2.1, build a polynomial model: Given the order 2, the polynomial model can be expressed as: f(x)=a2x 2 +a1x+a0 Among them, a2 and a1 are the coefficients that need to be solved; Step 5.2.2, define the error metric: Use mean squared error (MSE) as the error metric: Where m is the number of data points, (x i ,y i ) is a given data point, and each coefficient a i (i=0,1,…,m) find the partial derivative and set it to 0. Use the linear equation system to express the value of the polynomial f(x) at each data point x as the coefficient a i The linear combination of and solve this linear equation system to find the coefficient that minimizes the MSE; Step 5.2.3: Use stepwise regression techniques to evaluate the fit and determine the polynomial order: Starting from the 2nd order term, gradually increase the order, evaluate the performance of the model at each step, and repeat steps 5.2.1 to 5.2.

3. When increasing the order no longer significantly improves the model performance, stop increasing the order and use the coefficient of determination R 2 Size evaluation fitting effect, determination coefficient R 2 The formula is: Step 5.2.4, determine the polynomial curve equation: The equation of the fitted polynomial curve is determined as: f(x)=a m x m +a m-1 x m-1 +...+a1x+a 0。 10. The bogie weld eddy current testing method as claimed in claim 8, characterized in that: Planning the detection track of the eddy current detection probe tooling 12 in step 6 specifically includes the following: Step 6.1, define the base coordinate system as [B], the gantry coordinate system [G], the robot base coordinate system [MB], the probe holder coordinate system [MH], the head fixture 1 coordinate system [T], the displacement device coordinate system [P], and the bogie coordinate system [BG]; Step 6.2, describe the posture of the eddy current detection probe fixture 12: The position of the robot 8 refers to the vector change of the position of the eddy current detection probe fixture 12 relative to the origin of the basic coordinate system in the basic coordinate system. The position point P of the eddy current detection probe fixture 12 can be described as B P; The posture of the eddy current detection probe fixture 12 can be expressed as the basic coordinate system XYZ undergoing three coordinate rotations to become a new coordinate system UVW, where U, V, and W are the three coordinate axes of the eddy current detection probe fixture 1 coordinate system, and the rotation matrix R is: The rotation matrix R is expressed by the rotation angle γ, the pitch angle β, and the yaw angle α, and the rotation matrix R of the new expression is: R xyz =R x (a)R y (b)R z (c) Combining the above posture and position description, the posture of the eddy current detection probe fixture 1 coordinate system is obtained: Transforms the matrix [T] into a transformation matrix from [B] to [T] have to: Step 6.3: Description of the position and posture of the trajectory point in the six-axis robot base coordinate system [MB]: definition is the transformation matrix from the base coordinate system to the gantry coordinate system, is the transformation matrix from the gantry coordinate system to the six-axis robot base, is the transformation matrix from the six-axis robot probe holder 1 coordinate system to the six-axis robot base coordinate system, is the transformation matrix from the eddy current detection probe fixture 1 coordinate system to the six-axis robot probe holder 1 coordinate system, is the transformation matrix from the displacement device coordinate system to the basic coordinate system, is the transformation matrix from the bogie coordinate system to the displacement device coordinate system; Trajectory points in the bogie coordinate system In the six-axis robot base coordinate system, it is expressed as From the calculation formula: During the detection process, the probe fixture 12 is in contact with the bogie 1. At this time, the trajectory to be detected on the surface of the bogie 1 is equivalent to the posture of the eddy current detection probe fixture 12, that is, Similarly, the position description of each midpoint of the weld arc in the six-axis robot base coordinate system [MB] is obtained; Step 6.4, determine the detection trajectory: The coordinates of point E in each frame of image are fitted with a quasi-uniform cubic B-spline curve to obtain the detection trajectory curve L1, the coordinates of point F in each frame of image are fitted with a quasi-uniform cubic B-spline curve to obtain the detection trajectory curve L2, and the coordinates of each midpoint in the weld arc in each frame of image are fitted with a quasi-uniform cubic B-spline curve to obtain the detection trajectory curves L3, L4...L n .

Images