A device and method for improving the fatigue performance of train body structure

Abstract

This invention discloses a device and method for improving the fatigue performance of train body structures, comprising an ultrasonic impact gun, a robot, a control system, and a camera. The ultrasonic impact gun is mounted on the robot's robotic arm, and the control system is connected to the ultrasonic impact gun, the robot, and the camera. This invention enables automated ultrasonic impact on train body samples, significantly improving the ultrasonic impact effect, increasing production efficiency, reducing labor intensity, and achieving intelligent production.

Description

Technical Field

[0001] This invention specifically relates to a device and method for improving the fatigue performance of train body structures. Background Technology

[0002] Ultrasonic impact technology utilizes an ultrasonic impact device to convert input electrical energy into mechanical energy via a transducer. This mechanical energy is then amplified by a variable amplitude rod and applied to the surface of the impacted component. Upon impact, the surface metal undergoes severe plastic deformation, eliminating some harmful residual tensile stress and introducing beneficial compressive stress. Furthermore, due to the impact, the microstructure of the material surface becomes denser, more uniform, and more stable, significantly improving microhardness, wear resistance, and corrosion resistance. This is beneficial for the material's operation in harsh environments. After half a century of development, this technology and equipment have matured and are widely used in manufacturing. The treated welded surface can even reach the nanometer level, significantly improving the fatigue life of welded structures.

[0003] Currently, ultrasonic shock stress relief equipment is all handheld, making it difficult to achieve standardization and intelligence. It requires manual experience to control the impact force and timing, resulting in extremely non-standard and irregular impacts. This makes it impossible to effectively eliminate and reduce the high concentration of stress. Ineffective impacts not only fail to ensure train safety and extend train life, but may also cause damage to the train and accelerate its aging process. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a device and method for improving the fatigue performance of train body structure, which addresses the above-mentioned defects in the existing technology, realizes automated ultrasonic impact on train body samples, greatly improves the ultrasonic impact effect, increases production efficiency, reduces labor intensity, and realizes intelligent production.

[0005] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0006] A device for improving the fatigue performance of train body structure includes an ultrasonic impact gun, a robot, a control system, and a camera. The ultrasonic impact gun is mounted on the robotic arm of the robot, and the control system is connected to the ultrasonic impact gun, the robot, and the camera.

[0007] According to the above technical solution, the robot is installed on a mobile trolley or mobile gantry, and the control system has a built-in database that stores ultrasonic impact schemes corresponding to different welding samples of the train body structure.

[0008] According to the above technical solution, the mobile trolley is equipped with wheels at the bottom, hydraulic support legs, a camera, a signal receiving antenna, and a crash bar at the front end of the mobile trolley.

[0009] According to the above technical solution, the mobile gantry includes two parallel guide rails, a traveling seat, a crossbeam, and columns. The two ends of the crossbeam are connected to columns, and the two columns are respectively set on the two guide rails through the two traveling seats. The crossbeam and columns can move back and forth along the guide rails through the traveling seats. A slide rail is provided on the crossbeam along the length of the crossbeam, and the robot is set on the slide rail and can move back and forth along the slide rail.

[0010] According to the above technical solution, the robot includes a robotic arm forearm, a robotic arm upper arm, a T-junction rotating component, a base rotating component, and a main arm rotating component. An ultrasonic impact gun is mounted on the robotic arm forearm. The robotic arm forearm is connected to one end of the robotic arm upper arm through the T-junction rotating component, and the other end of the robotic arm upper arm is connected to the base rotating component through the main arm rotating component. Motors are connected to the T-junction rotating component, the main arm rotating component, and the base rotating component.

[0011] According to the above technical solution, the ultrasonic impact gun is mounted on the robot's robotic arm via a sleeve. The sleeve includes an upper section and a lower section. One end of the upper section is connected to the robot's robotic arm, and the other end of the upper section is sleeved with the lower section. The ultrasonic impact gun is mounted on the lower section, and a spring connects the upper and lower sections.

[0012] According to the above technical solution, there are multiple cameras.

[0013] A fatigue performance elimination method using the above-described train body structure fatigue performance improvement device includes the following steps: first, determining the type of train material sample; second, determining the ultrasonic impact scheme based on the type of train material sample; third, the control system identifying the weld position in the sample through a camera; and fourth, using a robot to drive an ultrasonic impact gun to impact the weld position of the sample according to the determined impact scheme.

[0014] According to the above technical solution, when the train material sample is the side wall of a train made of 6005-T6 aluminum alloy, the ultrasonic impact scheme for the sample is as follows: Step 1, a single-headed impact needle is selected for the ultrasonic impact gun, the impact current is 1.2A~1.5A, the impact time is 6-8min, the impact gun moving speed is 8-12mm / s, and the impact is performed along the weld length, with 2 impacts; Step 2, a three-headed impact needle is selected for the ultrasonic impact gun, the impact current is 2.0A~2.5A, the impact time is 2-4min, the impact gun moving speed is 10-12mm / s, and the impact is performed once.

[0015] When the train material sample is the end of the wing plate, traction seat, or shock absorber of the train, the ultrasonic impact scheme for the sample is as follows: a three-needle impact needle is selected, the impact current is 1.2A-1.5A, the coverage is 200%-300%, and the residual stress level reaches -150 to 190 MPa.

[0016] When the train material sample is the welded part of a 6005-T6, A6N01, or A7N01 aluminum alloy welded joint, the ultrasonic impact scheme for the sample is as follows: first, a three-headed impact needle is selected, the impact current is 1.2A to 1.5A, the coverage is 100% to 300%, and the residual stress level reaches -110 to 170MPa.

[0017] According to the above technical solution, the specific process for identifying the weld location is as follows:

[0018] Step 1: Acquire sample images using a camera, and denoise the sample images using Gaussian filtering to reduce noise interference with image recognition;

[0019] Step 2: Binarize the sample image and use the gray-level differences in the image to achieve image segmentation technology, dividing the gray levels of the sample background area and the sample area into two different levels for edge detection.

[0020] Step 3: Perform Hough transform on the edge-detected image to detect straight lines;

[0021] Step 4: After detecting the straight line, some intersection point coordinates can be obtained. By comparing the intersection point coordinates with the ROI region after removing complex backgrounds, if the intersection point coordinates are within a certain threshold range of the ROI region, they can be regarded as one of the boundary points of the weld. The position of the intersection point coordinates obtained by fitting the straight line in the ROI region can be determined. Then, the nearest neighbor point of the point is searched. If the distance d between the points in the neighborhood is less than 2 pixels, the two points are considered as one point coordinate, and the size is the average of the two coordinate sizes.

[0022] Step 5: After image preprocessing, stereo matching and coordinate calculation are performed. Images containing the same object are captured by two cameras from two different positions. The disparity is calculated by matching the corresponding regions. The three-dimensional structural information of the target object is recovered through the reverse process. By establishing a reasonable objective function and constraints, the equation is solved using an optimization algorithm. The coordinate values ​​of the object in the image are obtained by triangulation.

[0023] The present invention has the following beneficial effects:

[0024] In this invention, the control system identifies the sample and weld seam through a camera, and uses a robot to drive an ultrasonic impact gun to achieve automated ultrasonic impact on the train body sample. It can provide customized, refined and standardized impact solutions, greatly improve the ultrasonic impact effect, increase production efficiency, reduce labor intensity, realize intelligent production, and achieve nanoscale grain size on the surface of the metal through ultrasonic impact. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the impact head in an embodiment of the present invention;

[0026] Figure 2 This is a schematic diagram of the structure of the vehicle-mounted train body structure fatigue performance improvement device in this embodiment of the invention;

[0027] Figure 3 This is a perspective view of the vehicle-mounted train body structure fatigue performance improvement device in an embodiment of the present invention;

[0028] Figure 4 This is a perspective view of the fatigue performance improvement device for gantry-type train body structure in an embodiment of the present invention;

[0029] Figure 5 This is a schematic diagram of the fatigue performance improvement device for train body structure in an embodiment of the present invention;

[0030] In the diagram, 1-upper section of the sleeve, 2-unequal-distance spring, 3-lower section of the sleeve, 4-ultrasonic impact gun, 5-sleeve fixing bolt, 6-sleeve fixing hole, 7-robotic arm forearm, 8-robotic arm upper arm, 9-binocular recognition camera, 10-hydraulic support leg, 11-cart compartment door, 12-rotating component of the tee section, 13-motor, 14-signal receiving antenna, 15-anti-collision bar, 16-base rotating component, 17-main arm rotating component, 18-I-beam base, 19-guide rail, 20-walking seat, 21-column, 22-camera, 23-crossbeam, 24-robot. Detailed Implementation

[0031] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0032] Reference Figures 1-5 As shown, in one embodiment 1 of the present invention, a train body structure fatigue performance improvement device includes an ultrasonic impact gun 4, a robot 24, a control system, and a camera 22. The ultrasonic impact gun 4 is mounted on the robotic arm of the robot 24, and the control system is connected to the ultrasonic impact gun 4, the robot 24, and the camera 22.

[0033] Furthermore, the control system has a built-in database that stores ultrasonic impact schemes corresponding to different welding samples of the train body structure. The ultrasonic impact schemes in the database are obtained through a large number of basic experiments and then manually entered into the database, or obtained through intelligent training based on a large amount of basic experimental data. Through extensive research, customized and standardized solutions for improving the fatigue performance of the train body are provided.

[0034] Example 2

[0035] like Figure 2-3As shown, based on Embodiment 1, the technical features of the mobile vehicle are added, resulting in Embodiment 2 having even better performance.

[0036] Furthermore, robot 24 is mounted on a mobile trolley with wheels at the bottom and hydraulic support legs 10 on one side of the wheels. Camera 22 is mounted on the mobile trolley, which also has a signal receiving antenna 14 and a crash bar 15 at the front. The crash bar is located at the front of the mobile trolley, which has a trolley door 11 and a control system located inside the trolley door 11.

[0037] Example 3

[0038] like Figure 4 As shown, the technical feature of a movable gantry frame is added to the basis of Embodiment 1, and the performance of Embodiment 1 after the limitation is better.

[0039] Furthermore, the robot 24 is mounted on a mobile gantry frame, which includes two parallel guide rails 19, a traveling seat 20, a crossbeam 23, and columns 21. The two ends of the crossbeam 23 are respectively connected to the columns 21. The two columns 21 are respectively mounted on the two guide rails 19 via the two traveling seats 20. The crossbeam 23 and the columns 21 can move back and forth along the guide rails 19 via the traveling seats 20. A slide rail is provided on the crossbeam 23 along the length of the crossbeam. The robot 24 is mounted on the slide rail and can move back and forth along the slide rail.

[0040] Furthermore, the guide rail 19 is mounted on the foundation via the I-beam base 18.

[0041] Example 4

[0042] like Figure 4-5 As shown, based on Example 1, specific structural features of the robot were added, resulting in better performance of Example 1 after the limitations were made.

[0043] Furthermore, the robot includes a robotic arm forearm 7, a robotic arm upper arm 8, a T-junction rotating component 12, a base rotating component 16, and a main arm rotating component 17. An ultrasonic impact gun 4 is mounted on the robotic arm forearm 7. The robotic arm forearm 7 is connected to one end of the robotic arm upper arm 8 through the T-junction rotating component 12, and the other end of the robotic arm upper arm 8 is connected to the base rotating component 16 through the main arm rotating component 17. Motors 13 are connected to the T-junction rotating component 12, the main arm rotating component 17, and the base rotating component 16.

[0044] Example 5

[0045] like Figure 1 As shown, the installation structure of the ultrasonic impact gun 4 is added to the basis of Example 1, and the performance of Example 1 is better after the limitation.

[0046] Furthermore, the ultrasonic impact gun 4 is mounted on the robot's robotic arm via a sleeve. The sleeve includes an upper section 1 and a lower section 3. One end of the upper section 1 is connected to the robot's robotic arm, and the other end of the upper section 1 is sleeved on the lower section 3. The ultrasonic impact gun 4 is mounted on the lower section 3, and an unequal-pitch spring 2 is connected between the upper section 1 and the lower section 3.

[0047] Furthermore, there are multiple cameras 22; they are set at the front end of the mobile trolley or on the crossbeam of the mobile gantry; the cameras are binocular recognition cameras 9 or binocular cameras.

[0048] Example 6

[0049] like Figure 5 As shown, based on Example 1, the characteristic limitation of the fatigue performance elimination method is added, and the performance of Example 1 after the limitation is better.

[0050] A fatigue performance elimination method using the above-described train body structure fatigue performance enhancement device includes the following steps: first, determining the type of train material sample; second, determining the ultrasonic impact scheme for the sample based on the type of train material sample; third, the control system identifies the weld position in the sample through a camera; fourth, the robot drives the ultrasonic impact gun 4 to impact the weld position of the sample according to the determined impact scheme; fifth, the same sample can be impacted by multiple of the above-described train body structure fatigue performance enhancement devices.

[0051] Furthermore, when the train material sample is the side wall of a CHR5 train made of 6005-T6 aluminum alloy, the ultrasonic impact scheme for the sample is as follows: Step 1, a single-headed impact needle is selected for the ultrasonic impact gun 4, the impact current is 1.2A~1.5A (selecting the impact current is equivalent to selecting the corresponding impact intensity; in this embodiment, the optimal impact current in Step 1 is 1.4A), the impact time is 6-8min (in this embodiment, the optimal impact time in Step 1 is 7min), the impact gun moving speed is 8-12mm / s (in this embodiment, the optimal impact gun moving speed in Step 1 is 10mm / s), and the impact is performed along the weld length. The number of impacts is 2; in step 2, a three-headed impact needle is selected for the ultrasonic impact gun 4, the impact current is 2.0A~2.5A (in this embodiment, the optimal impact current in step 2 is 2.33A), the impact time is 2-4min (in this embodiment, the optimal impact time in step 2 is 3min), the impact gun moving speed is 10-12mm / s (in this embodiment, the optimal impact gun moving speed in step 2 is 11mm / s), and the number of impacts is 1; in this state, the first and second steps can use two of the aforementioned train body structure fatigue performance improvement devices arranged sequentially according to the process and working simultaneously, so that frequent replacement of the impact needle is not required;

[0052] When the train material sample is the end of the wing plate, traction seat, or shock absorber of the train, the ultrasonic impact scheme for the sample is as follows: select a three-needle impact needle, the impact current is 1.2A-1.5A (i.e. impact strength), the coverage is 200%-300%, and the residual stress level reaches -150 to 190 MPa.

[0053] When the train material sample is the welded part of a 6005-T6, A6N01, or A7N01 aluminum alloy welded joint, the ultrasonic impact scheme for the sample is as follows: first, select a three-headed impact needle, the impact current is 1.2A to 1.5A (i.e., impact strength), the coverage is 100% to 300%, and the residual stress level reaches -110 to 170MPa.

[0054] Furthermore, coverage rate refers to the following: First, a layer of colored glaze or fluorescent glaze is applied to the surface of the workpiece. Then, the workpiece is shot-blasted according to the process parameters. After each shot blasting, the workpiece is removed and observed under a microscope or magnifying glass to determine the proportion of the remaining coating on the surface. If 20% remains, the coverage rate is 80%. When only 2% remains, i.e., the coverage rate is 98%, it can be considered as completely removed, i.e., the coverage rate is 100%. At this point, there is a time requirement. If a coverage rate of 400% is achieved, it would take four times that time.

[0055] Furthermore, the specific process for identifying the location of the weld seam in the sample is as follows:

[0056] Step 1: Acquire sample images using a camera, and denoise the sample images using Gaussian filtering to reduce noise interference with image recognition;

[0057] Step 2: Binarize the sample image and use the gray-level differences in the image to achieve image segmentation technology, dividing the gray levels of the sample background area and the sample area into two different levels for edge detection.

[0058] Step 3: Perform Hough transform on the edge-detected image to detect straight lines; in essence, it finds all the pixels that make up the straight line. The basic principle is to use the image edge points to calculate the trajectory of the reference points in the parameter space, transform the image space to the parameter space, and realize the line detection by processing the parameters.

[0059] Step 4: After detecting the straight line, some intersection point coordinates can be obtained. By comparing the intersection point coordinates with the ROI region after removing complex backgrounds, if the intersection point coordinates are within a certain threshold range of the ROI region, they can be regarded as one of the boundary points of the weld. The position of the intersection point coordinates obtained by fitting the straight line in the ROI region can be determined. Then, the nearest neighbor point of the point is searched. If the distance d between the points in the neighborhood is less than 2 pixels, the two points are considered as one point coordinate, and the size is the average of the two coordinate sizes.

[0060] Step 5: After image preprocessing, stereo matching and coordinate calculation are performed. Images containing the same object are captured by the camera from two different positions. The disparity is calculated by matching the corresponding regions. The three-dimensional structural information of the target object is recovered through the reverse process. By establishing a reasonable objective function and constraints, the equation is solved using an optimization algorithm. The coordinate values ​​of the object in the image are obtained by triangulation.

[0061] Furthermore, the ROI region is the region of interest.

[0062] For non-weld seam areas, due to the lack of image features, workers need to affix auxiliary markers to aid in localization, depending on the specific situation. The following uses a weld seam as an example to illustrate the implementation of this technology. Since the image acquired by the binocular camera not only includes the weld seam but also the complex background of the weld seam area, image preprocessing is required. During image preprocessing, firstly, Gaussian filtering is used to denoise the image, reducing noise interference with image recognition. Secondly, image binarization is performed, utilizing grayscale differences to segment the image, dividing the grayscale of the workpiece background area and the workpiece area into two different levels; (a reasonable threshold is selected, where pixels reach the threshold and are equal to 1, otherwise 0, thus generating the corresponding binarized image.) Thirdly, edge detection is performed.

[0063] Furthermore, the specific process of edge detection in step 2 is as follows: First, the image contour is roughly calculated, then the detected contour points are connected by connection rules, and irrelevant points are removed to retain the important structural information of the image and improve the speed of image processing; second, an N×N kernel is used to convolve with each pixel in the image, and then an appropriate threshold is selected according to the actual situation to extract the edge part.

[0064]

[0065] in

[0066]

[0067]

[0068] Using the two convolution templates shown in Equations (1), (2), and (3), we can detect the horizontal and vertical edges.

[0069] Working principle of the invention:

[0070] The first step involved conducting extensive finite element simulations of the car body through basic research. To closely reflect the actual loads experienced by the train, the fatigue loads on the car body were simulated by measuring the inertial acceleration in three directions. The fatigue load conditions in the EN12663:2010 standard were used to analyze the fatigue strength of the car body, thereby understanding the typical fatigue-prone structural characteristics of the train. Specifically, the areas with the greatest fatigue damage were located at the stress concentration points of the welds, and most fatigue damage occurred at the traction beams, floor, air duct uprights, and the connection points between the underframe side beams and the floor.

[0071] The second step involves experimentally studying the relationship between the surface hardness and stress changes of the main materials and structures of the train after stress concentration and fatigue damage, and the intensity, time, moving speed of the impact gun, number of ultrasonic impacts, and type of ultrasonic impact head. This is done through ANSYS simulation analysis, where the train body is simulated, and the results are imported into ANSYS. Simulation analysis yields solutions, and impact schemes including impact needle head, impact current, impact time, and moving speed of the impact gun are derived from the experimental results and recorded in the database. For example, a life-extending scheme was developed for the sidewall of the CHR5 model, which uses 6005-T6 aluminum alloy. The scheme consists of two steps: the first step uses a single-headed impact needle with an impact current of 1.4A, an impact time of 7 minutes, an impact gun moving speed of 10 mm / s, and 2 impacts; the second step uses a three-headed impact needle with an impact current of 2.33A, an impact time of 3 minutes, an impact gun moving speed of 11 mm / s, and 1 impact. Finally, the scientific validity and rationality of the proposed scheme were verified using an optical microscope. The results showed a significant increase in sample material density and a corresponding decrease in stress level, confirming the rationality and effectiveness of the surface modification scheme. Based on the experimental results, a standardized intelligent ultrasonic impact database was established, featuring a visual interface, access control for data within the database, user permission management, and the ability to generate impact schemes. Through preliminary finite element analysis of the train, stress cloud maps of the car body were obtained. Areas within the car body requiring ultrasonic impact were marked using washable pigment, laying the foundation for subsequent impact scheme development.

[0072] The third step involves selecting a reliable and accurate impact scheme from the database based on the required impact location. This scheme includes impact frequency, impact amplitude, impact pulse width, and equipment current. The scheme information is then transmitted to the ultrasonic impact robot. The first ultrasonic impact robot, mounted on the gantry, primarily impacts the weld seam area on the exterior of the vehicle body, while the second ultrasonic impact robot, mounted on the trolley, primarily impacts the high-stress areas inside the vehicle body. The two robots work together to complete the ultrasonic impact work inside and outside the vehicle. Both robots are equipped with binocular cameras, which utilize binocular vision technology to accurately identify and extract the weld seam location at the end of the robotic arm without the aid of other sensors.

[0073] The fourth step involves the ultrasonic impact robot identifying the weld seam and marked stress concentration areas according to the impact plan. It then plans the movement of its robotic arm and issues commands to perform ultrasonic impact. Considering the conditions of the train body manufacturing workshop and the requirements for both internal and external impacts, two ultrasonic impact robots were designed: one mounted on a gantry and the other mounted on a trolley. The gantry-mounted ultrasonic impact robot can work in conjunction with the welding robot to achieve in-process impact during welding, better improving the residual stress distribution of the welded structure and significantly increasing the efficiency of ultrasonic impact operations. The trolley-mounted ultrasonic impact robot allows for remote control and enables impact operations on the interior of the assembled car body. These two methods complement each other, achieving the goal of automating the impact process across the entire train. The impact head mounted on the gantry receives the command and moves to the designated position to identify and ultrasonically impact the weld seam on the exterior of the train. The ultrasonic impact head mounted on the trolley receives the work command, arrives at the marked impact area, and then identifies and ultrasonically impacts the marked stress concentration areas inside the train.

[0074] Table 1 Comparison of surface hardness and stress distribution of the vehicle body before and after impact.

[0075]

[0076] Table 2 Comparison of fatigue performance before and after ultrasonic impact.

[0077]

[0078]

[0079] This project conducts extensive finite element simulations of the train body, simulating fatigue loads by measuring inertial acceleration in three directions. The fatigue load conditions in the EN12663:2010 standard are used for analysis to understand the fatigue performance of the train body structure. Based on this, research is conducted on relevant factors affecting the fatigue performance of the train body structure, focusing on revealing the fatigue damage mechanism and evolution law of the body structure. The project optimizes the fatigue improvement technology of the body structure based on impact strengthening, conducting numerous ultrasonic impact experiments on the train's materials and structure, and establishing a standardized intelligent ultrasonic impact database using ANSYS analysis. Surface hardness, stress distribution, and basic train information are stored in the database, which is then retrieved by a terminal to provide operators with impact plans. These plans are then transmitted to an ultrasonic impact robot, which performs the impact, thereby improving the fatigue performance of the train body structure.

[0080] The above are merely preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. Therefore, any equivalent changes made in accordance with the claims of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A fatigue performance improvement method using a train car body structure fatigue performance improvement device, characterized by, The train body structure fatigue performance improving device comprises an ultrasonic impact gun, a robot, a control system and a camera, the ultrasonic impact gun is arranged on a mechanical arm of the robot, and the control system is connected with the ultrasonic impact gun, the robot and the camera respectively; The fatigue performance improving method comprises the following steps: firstly, determining the type of the train material sample, determining the ultrasonic impact scheme of the sample according to the type of the train material sample, identifying the weld position in the sample by the camera, and driving the ultrasonic impact gun to impact the weld position of the sample according to the determined impact scheme by the robot. The specific steps of determining the ultrasonic impact scheme of the sample according to the type of the train material sample are as follows: When the train material sample is the side wall of a train made of 6005-T6 aluminum alloy, the ultrasonic impact scheme for the sample is as follows: step 1, selecting a single-head impact needle for the ultrasonic impact gun, the impact current is 1.2A-1.5A, the impact time is 6-8min, the moving speed of the impact gun is 8-12mm / s, the impact is performed along the length of the weld, and the impact frequency is 2 times; step 2, selecting a three-head impact needle for the ultrasonic impact gun, the impact current is 2.0A-2.5A, the impact time is 2-4min, the moving speed of the impact gun is 10-12mm / s, and the impact frequency is 1 time; When the train material sample is the end of a wing plate or a traction seat or a shock absorber of a train, the ultrasonic impact scheme for the sample is as follows: selecting a three-needle impact needle, the impact current is 1.2A-1.5A, the coverage rate is 200%-300%, and the residual stress level reaches-150-190Mpa; When the train material sample is a welded joint of a 6005-T6 or A6N01 or A7N01 aluminum alloy, the ultrasonic impact scheme for the sample is as follows: selecting a three-head impact needle, the impact current is 1.2A-1.5A, the coverage rate is 100%-300%, and the residual stress level reaches-110-170Mpa; The robot is arranged on a mobile trolley or a mobile gantry, and the control system is provided with a database, which stores the ultrasonic impact schemes corresponding to different welded samples of the train body structure.

2. The fatigue performance improvement method according to claim 1, characterized by, The mobile trolley is provided with wheels at the bottom and hydraulic support legs, the camera is arranged on the mobile trolley, and the mobile trolley is further provided with a signal receiving antenna and an anti-collision rod.

3. The fatigue performance improvement method of claim 1, wherein The mobile gantry comprises two parallel arranged guide rails, a walking base, a cross beam and a stand, the two ends of the cross beam are respectively connected with the stands, the two stands are arranged on the two guide rails respectively, the cross beam and the stands move back and forth along the guide rails through the walking bases, the cross beam is provided with a slide rail along the length direction of the cross beam, and the robot is arranged on the slide rail and moves back and forth along the slide rail.

4. The fatigue property improving method according to any one of claims 1 to 3, characterized by, The robot comprises a mechanical arm small arm, a mechanical arm large arm, a three-way part rotating component, a base rotating component and a main arm rotating component, the ultrasonic impact gun is arranged on the mechanical arm small arm, the mechanical arm small arm is connected with one end of the mechanical arm large arm through the three-way part rotating component, the other end of the mechanical arm large arm is connected with the base rotating component through the main arm rotating component, and the three-way part rotating component, the main arm rotating component and the base rotating component are all connected with motors.

5. The fatigue property improving method according to any one of claims 1 to 3, characterized by, The ultrasonic impact gun is arranged on the mechanical arm of the robot through a sleeve, the sleeve comprises an upper sleeve section and a lower sleeve section, one end of the upper sleeve section is connected with the mechanical arm of the robot, the other end of the upper sleeve section is sleeved with the lower sleeve section, the ultrasonic impact gun is arranged on the lower sleeve section, and a spring is connected between the upper sleeve section and the lower sleeve section.

6. The fatigue property improving method according to any one of claims 1 to 3, characterized by, The number of the cameras is multiple.

7. The fatigue performance improvement method of claim 1, wherein The process of identifying the position of the weld of the sample piece is as follows: Step 1: the image of the sample piece is collected through the camera, the image of the sample piece is denoised through Gaussian filtering, and the interference of noise on image recognition is reduced; Step 2: the image of the sample piece is binarized, the image is segmented by using the gray difference in the image, the gray of the background area and the sample area is divided into two different levels, and edge detection is performed; Step 3: the image subjected to the edge detection is subjected to Hough transform detection of straight lines; Step 4, after detecting the straight line, some intersection point coordinates can be obtained, by comparing the intersection point coordinates with the ROI region after eliminating the complex background, if the intersection point coordinates are located in a certain threshold range of the ROI region, they can be considered as one of the boundary points of the weld, by judging the position of the intersection point coordinates obtained by fitting the straight line in the ROI region; then search the nearest neighborhood point of the point, if the distance d of the neighborhood point is less than , then the two points are considered as one point coordinate, and the size is the average of the sizes of the two point coordinates; Step 5: after the image is preprocessed, stereo matching and coordinate calculation are performed; the images containing the same object photographed from two different positions by two cameras are matched to calculate the parallax, the three-dimensional structure information of the target piece is recovered through the reverse process, a reasonable target function and constraint condition are established, an optimization algorithm is used to solve the equation, and the coordinate value of the object in the image is obtained through triangulation.

Images