Bogie frame weld seam grinding method and system

Abstract

The present application provides a kind of to be related to the field of rail vehicle, provide a kind of bogie frame weld polishing method and system, bogie frame weld polishing method includes: obtaining base material position, steel pipe center point position and weld position;According to base material position, weld position, steel pipe radius and base material thickness, determine polishing track;According to polishing track, control polishing tool to carry out polishing movement with steel pipe center point position as the center of circle.Solve the core problem of difficult positioning and unintelligent trajectory planning in manual and traditional automatic polishing, realize the upgrading from automation to intelligent autonomy, overcome the problem of poor polishing track accuracy caused by workpiece size manufacturing error, positioning and clamping error and welding deformation, ensure polishing effect consistency and overall quality.

Description

Technical Field

[0001] This invention relates to the field of rail vehicles, and provides a method and system for grinding the weld seams of a bogie frame. Background Technology

[0002] In the manufacturing of large equipment such as rail transit, the welding quality (weld quality) of key components such as train chassis bogies is a crucial guarantee for the stability and safety of the entire vehicle. The requirements for the precision and efficiency of weld grinding are becoming increasingly stringent. Traditional manual grinding methods are no longer sufficient to meet these requirements due to their low efficiency, inconsistent processing quality, high labor intensity, and harsh working environment (high noise, high pollution). Furthermore, due to unavoidable issues such as workpiece dimensional manufacturing errors, positioning and clamping errors, and welding deformation, traditional robotic grinding methods often struggle to guarantee the accuracy of the grinding trajectory, thus affecting the consistency of the grinding effect and the overall quality.

[0003] While some automated weld grinding systems have emerged on the market, they primarily rely on offline programming and are only suitable for parts with very standard dimensions. They suffer from limited applicability, insufficient flexibility, and high costs. Furthermore, the actual grinding trajectory often deviates from the theoretical design trajectory, leading to inconsistent grinding results and potentially causing safety hazards. For welds with complex shapes and varied paths, such as circumferential welds in structural frames, the adaptability and precision of existing technologies still need improvement. Summary of the Invention

[0004] This invention provides a grinding method and system for the weld seams of a bogie frame, which addresses one of the deficiencies in related technologies. It solves the core problems of difficult positioning and unintelligent trajectory planning in manual and traditional automated grinding, and achieves an upgrade from automation to intelligent autonomy. It overcomes the problems of poor grinding trajectory accuracy caused by workpiece size manufacturing errors, positioning and clamping errors, and welding deformation, ensuring consistent grinding effect and overall quality.

[0005] This invention provides a method for grinding welds on a bogie frame, comprising: Obtain the location of the base material, the center point of the steel pipe, and the location of the weld. The grinding trajectory is determined based on the location of the base material, the location of the weld, the radius of the steel pipe, and the thickness of the base material. According to the grinding trajectory, the grinding tool is controlled to perform grinding motion with the center point of the steel pipe as the center.

[0006] According to one embodiment of the present invention, it further includes: Obtain the contour of the ground area; The grinding trajectory is obtained by comparing the contour of the ground area with a set contour. The grinding tool is controlled to perform additional grinding on the already ground area along the grinding trajectory.

[0007] According to one embodiment of the present invention, obtaining the base material position and the weld position includes: The position of the base material is obtained by a 3D scanning device, and the position of the center point of the steel pipe is also obtained. The weld position is obtained by line scanning laser based on the location of the base material.

[0008] According to one embodiment of the present invention, obtaining the position of the base material and the position of the center point of the steel pipe by means of a 3D scanning device includes: The 3D scanning device is used to scan the area to be polished of the structure from multiple angles to obtain point cloud data of the area to be polished. Using the region growing method or model matching method, the point cloud data of the parent material region and the point cloud data of the cylindrical surface region of the steel pipe are segmented from the point cloud data of the region to be polished. Based on flat panel point cloud data, a plane equation is obtained by fitting a plane using the RANSAC algorithm. The fitted plane represents the spatial orientation of the parent material. Based on the point cloud data of the cylindrical surface region of the steel pipe, the equation of the central axis and the radius of the cylindrical surface are obtained by fitting the cylindrical surface using a cylindrical surface fitting algorithm; An initial reference center point is obtained based on the intersection or nearest point of the central axis of the cylindrical surface and the fitting plane.

[0009] According to one embodiment of the present invention, obtaining the weld position based on the base material position using a line-scan laser includes: Based on the location of the base material and the theoretical weld direction, the planned scanning path is obtained; The weld cross-section and the two-dimensional contour lines of the base material are obtained by scanning along the planned scanning path using a control line laser. By analyzing the cross-section of each weld and the two-dimensional contour line of the base material, the actual three-dimensional spatial trajectory point cloud data of the weld is obtained. The actual three-dimensional spatial trajectory point cloud data of the weld is smoothed by using spatial circle fitting or spline curve fitting algorithms to obtain the robot center point reference path.

[0010] According to one embodiment of the present invention, determining the grinding trajectory based on the base material position, the weld position, the steel pipe radius, and the base material thickness includes: The grinding center is determined based on the central axis of the cylindrical surface and the initial reference center point; Based on each target point on the robot center point reference path, obtain the normal plane of each target point relative to the central axis of the cylindrical surface; Within the normal plane of each target point relative to the central axis of the cylindrical surface, based on the geometry of the grinding wheel of the grinding tool and the preset grinding entry angle, the precise position of the center point of the grinding tool and the posture of the grinding tool are obtained, and the grinding trajectory executed by the robot driving the grinding tool is generated.

[0011] According to one embodiment of the present invention, obtaining the contour of the ground area includes: After one or more grinding operations, the ground area is scanned along the planned scanning path using a control line laser to obtain the actual grinding contour point cloud data.

[0012] According to one embodiment of the present invention, obtaining a grinding trajectory pair by comparing the contour of the ground area with a set contour includes: By comparing the actual grinding contour point cloud data with the contour surface of the set contour in the same coordinate system, the normal distance from each measurement point of the actual grinding contour point cloud data to the contour surface of the set contour is obtained, forming a margin distribution map. Determine whether the allowance in all areas is within the allowable tolerance zone. If there are areas with excessive allowance, obtain the grinding trajectory for areas with excessive allowance based on the allowance distribution map. If there are areas with negative allowance, record and alarm.

[0013] According to one embodiment of the present invention, before obtaining the position of the base material, the center point position of the steel pipe, and the weld position, the method further includes: Hand-eye calibration is performed on the grinding tools, 3D scanning device and line laser instrument to establish a unified relative positional relationship in the tool coordinate system and to establish a unified coordinate transformation relationship between the robot coordinate system, tool coordinate system and workpiece coordinate system. Import the data information of the three-dimensional digital model of the area to be polished, including the theoretical parameter values ​​of the polished area after polishing.

[0014] According to one embodiment of the present invention, after obtaining the initial reference center point based on the intersection or nearest point of the central axis of the cylindrical surface and the fitting plane, the method further includes: The point cloud data of the area to be polished is registered with the data information of the three-dimensional digital model of the area to be polished by the iterative nearest point algorithm to obtain the preliminary workpiece pose transformation matrix.

[0015] According to one embodiment of the present invention, obtaining the actual three-dimensional spatial trajectory point cloud data of the weld by analyzing the two-dimensional contour lines of each weld cross-section and the base material includes: Obtain feature points on the two-dimensional contour lines of each weld cross section and the base material; Based on the two-dimensional coordinates of the feature points in the tool coordinate system, combined with the robot's real-time pose, they are uniformly transformed into three-dimensional spatial points in the robot coordinate system. The set of all the three-dimensional spatial points forms the actual three-dimensional spatial trajectory point cloud data of the weld.

[0016] According to one embodiment of the present invention, the grinding trajectory ensures that when the grinding tool performs circumferential motion grinding around the axis of the steel pipe, the working surface of the grinding wheel always maintains an equidistant relationship with the theoretical cylindrical surface with the central axis of the cylindrical surface as the axis; in each segment of the grinding trajectory, the linear speed of the grinding tool, the robot feed speed, the feed amount, and the number of grinding passes are set.

[0017] According to one embodiment of the present invention, for each segment of the grinding trajectory, the set feed rate and feed speed are adjusted to 40% to 60% of the set feed rate and feed speed of the grinding trajectory.

[0018] This invention also provides a grinding system for bogie frame welds, characterized in that it is applied to the grinding method for bogie frame welds as described above, comprising: A 3D scanning device, the 3D scanning device being adapted to scan a workpiece; A line laser scanner, the line laser scanner being adapted to scan a workpiece; A grinding tool, said grinding tool being adapted to grind and polish welds; A robotic arm, which is connected to the 3D scanning device, the line laser, and the polishing tool respectively via a quick-change device, is adapted to drive the 3D scanning device, the line laser, and the polishing tool to move; A positioner, which is suitable for clamping, positioning and adjusting workpieces.

[0019] The present invention discloses a grinding method for the weld seam of a bogie frame, implemented based on a grinding system for the weld seam of a bogie frame. First, the positions of the base material, the center point of the steel pipe, and the weld seam are acquired. A two-stage positioning strategy of global coarse positioning and local fine positioning is adopted. First, a 3D scanning device scans the bogie frame to identify the spatial positions of the base material such as the flat plate and steel pipe. The central axis of the cylindrical surface of the steel pipe is fitted, and the center point position of the steel pipe is calculated. Then, based on the coarse positioning result of the base material, the weld seam contour is precisely acquired using a line laser scanner to extract the actual spatial position of the weld seam. Next, the grinding trajectory is determined. Based on the acquired base material position and the actual weld seam position, combined with the steel pipe radius and base material thickness parameters, and using the steel pipe's central axis as the geometric reference, the motion path of the grinding tool is calculated. The grinding trajectory is generated by constraints from the workpiece's geometric features, tool parameters, and tool posture, rather than simply replicating the weld seam path. Finally, the movement of the grinding tool is controlled. A robotic arm drives the grinding tool to move in a circular motion, strictly centered on the steel pipe's center point, ensuring that the working surface of the grinding wheel remains equidistant from the steel pipe's axis, achieving uniform grinding of the annular weld seam.

[0020] This invention employs a robotic arm to grip a specially designed grinding tool, combined with a vision system, for grinding circumferential welds. The weld is formed by the intersection of a flat plate and a steel plate. For coarse positioning, a 3D scanning device acquires feature points of the base material to identify its position, simultaneously determining the center point of the steel pipe. For fine positioning, a laser line scan is used to obtain the weld position based on the base material position. Trajectory planning determines the starting point of the trajectory based on the base material and weld positions, and the trajectory of the grinding tool is determined according to the steel pipe radius and base material thickness. During grinding, the robotic arm drives the grinding tool to move around the center of the steel pipe. This invention solves the core problems of difficult positioning and unintelligent trajectory planning in manual and traditional automated grinding, achieving an upgrade from automation to intelligent autonomy. It overcomes the problems of poor grinding trajectory accuracy caused by workpiece size manufacturing errors, positioning and clamping errors, and welding deformation, ensuring consistent grinding results and overall quality. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0022] Figure 1 This is one of the flowcharts for the grinding method of the weld seam of the bogie frame provided in the embodiment of the present invention; Figure 2 This is the second flowchart of the method for grinding the weld seams of the bogie frame provided in the embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of the electronic device provided in an embodiment of the present invention. Detailed Implementation

[0023] The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and should not be construed as limiting the scope of the invention.

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0025] In the description of the embodiments of the present invention, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of the present invention. In addition, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0026] In the description of the embodiments of the present invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of the present invention based on the specific circumstances.

[0027] In embodiments of the present invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0028] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0029] This invention provides a grinding system for bogie frame welds, applicable to the grinding of bogie frame welds. The system includes a 3D scanning device, a line laser, grinding tools, a robotic arm, and a positioner. The 3D scanning device is suitable for scanning the workpiece; the line laser is suitable for scanning the workpiece; the grinding tools are suitable for grinding the weld; the robotic arm is connected to the 3D scanning device, line laser, and grinding tools respectively via a quick-change device, suitable for driving the movement of the 3D scanning device, line laser, and grinding tools; and the positioner is suitable for clamping, positioning, and adjusting the workpiece.

[0030] The bogie frame weld grinding system of this invention mainly consists of a robotic arm, a 3D scanning device, a line laser, grinding tools, and a positioner. The robotic arm, acting as the actuator, uses a quick-change device to clamp the 3D scanning device, line laser, and grinding tools to perform related movements. The robotic arm can also quickly switch between the objects to be manipulated via the quick-change device. The 3D scanning device and line laser are used to scan the bogie components, achieving precise positioning and measurement of weld features. The grinding tools are used to perform grinding operations on the weld. The positioner is used to clamp and position the workpiece and is responsible for adjusting the workpiece's position and orientation as needed.

[0031] This invention deeply integrates advanced visual sensing technology and robot control technology. By replacing manual grinding with an integrated and automated grinding system, it improves the working environment and reduces labor intensity. Automatic end changing and positioner coordination achieve unmanned operation of the entire process. It can adapt to the circumferential weld of the bogie frame and achieve high precision, high efficiency and high consistency grinding requirements, supporting the intelligent manufacturing upgrade of rail transit equipment.

[0032] In this embodiment, the 3D scanning device can be a 3D laser camera, the line laser instrument can emit line scanning laser, and the grinding tool can be a special belt sander. The size of the grinding wheel of the belt sander should be designed according to the grinding arc requirements.

[0033] The grinding method for the weld seam of the bogie frame provided by the present invention will be described below. The grinding method for the weld seam of the bogie frame described below can be referred to in correspondence with the grinding system for the weld seam of the bogie frame described above.

[0034] like Figure 1 and Figure 2 As shown, an embodiment of the present invention provides a method for grinding the weld seams of a bogie frame, comprising: S100, obtain the location of the base material, the center point of the steel pipe, and the location of the weld; S200: The grinding path is determined based on the location of the base material, the location of the weld, the radius of the steel pipe, and the thickness of the base material. The S300 controls the grinding tool to perform grinding motions around the center point of the steel pipe, based on the grinding trajectory.

[0035] The grinding method for the weld seam of the bogie frame according to this invention is implemented based on a grinding system for the weld seam of the bogie frame. First, the positions of the base material, the center point of the steel pipe, and the weld seam are obtained. A two-stage positioning strategy of global coarse positioning and local fine positioning is adopted. First, the bogie frame is scanned using a 3D scanning device to identify the spatial positions of the base material such as the flat plate and steel pipe. The central axis of the cylindrical surface of the steel pipe is fitted, and the center point position of the steel pipe is calculated. Then, based on the coarse positioning result of the base material, the weld seam contour is accurately acquired using a line laser scanner to extract the actual spatial position of the weld seam. Next, the grinding trajectory is determined. Based on the obtained base material position and actual weld seam position, combined with the steel pipe radius and base material thickness parameters, and using the steel pipe central axis as the geometric reference, the motion path of the grinding tool is calculated. The grinding trajectory is generated by the constraints of workpiece geometric features, tool parameters, and tool posture, rather than simply reproducing the weld seam path. Finally, the movement of the grinding tool is controlled. The robotic arm drives the grinding tool to move in a circular motion, strictly centered on the center point of the steel pipe, ensuring that the working surface of the grinding wheel remains equidistant from the steel pipe axis, achieving uniform grinding of the annular weld seam.

[0036] This invention employs a robotic arm to grip a specially designed grinding tool, combined with a vision system, for grinding circumferential welds. The weld is formed by the intersection of a flat plate and a steel plate. For coarse positioning, a 3D scanning device acquires feature points of the base material to identify its position, simultaneously determining the center point of the steel pipe. For fine positioning, a laser line scan is used to obtain the weld position based on the base material position. Trajectory planning determines the starting point of the trajectory based on the base material and weld positions, and the trajectory of the grinding tool is determined according to the steel pipe radius and base material thickness. During grinding, the robotic arm drives the grinding tool to move around the center of the steel pipe. This invention solves the core problems of difficult positioning and unintelligent trajectory planning in manual and traditional automated grinding, achieving an upgrade from automation to intelligent autonomy. It overcomes the problems of poor grinding trajectory accuracy caused by workpiece size manufacturing errors, positioning and clamping errors, and welding deformation, ensuring consistent grinding results and overall quality.

[0037] In this embodiment, step S300 involves performing grinding and process monitoring. The robotic arm is equipped with a special grinding tool, which is then controlled to perform the grinding operation along a planned grinding trajectory. Simultaneously, motor current, vibration signals, etc., are monitored to provide early warnings for problems such as sanding belt breakage or abnormal wear.

[0038] According to one embodiment of the present invention, the grinding method for the weld seams of the bogie frame further includes: S400, obtain the contour of the ground area; S500 obtains the grinding trajectory by comparing the contour of the ground area with the set contour. The S600 uses a grinding tool to perform additional grinding on already ground areas by controlling the grinding tool to follow the grinding trajectory.

[0039] In this embodiment, after grinding is completed, the robot can be instructed to use a line laser scanner to scan the ground area again, comparing the ground contour with the original model or standard contour. When the contour is set to a preset 3D CAD model, the measured ground contour is directly compared with the preset 3D CAD model to generate a margin distribution map. It then automatically makes decisions and generates compensation grinding trajectories for locally exceeding the allowance, forming a closed-loop quality control system of "measurement-comparison-compensation." This solves the core problems of difficult positioning, unintelligent trajectory planning, and margin control based on experience in manual and traditional automated grinding, achieving an upgrade from automation to intelligent autonomy.

[0040] According to an embodiment of the present invention, step S100, obtaining the base material position and the weld position, includes: S110: The position of the base material is obtained through a 3D scanning device, and the position of the center point of the steel pipe is also obtained. S120 uses a line-scan laser to obtain the weld position based on the base material position.

[0041] In this embodiment, step S100 involves obtaining the center point positions of the base material and the steel pipe through 3D scanning and the weld position through line laser scanning. A robotic arm carrying a 3D scanning device scans the area to be ground on the frame from multiple angles to acquire point cloud data. The point clouds of the flat plate and steel pipe are segmented using an algorithm, and the plane and cylindrical surfaces are fitted to obtain the spatial orientation of the base material and the center point of the steel pipe. Then, using the coarse positioning position of the base material as a reference, a line laser scanning path is planned. The line laser instrument high-frequency acquires the two-dimensional contour of the weld cross-section, identifying features such as the weld toe and weld root to obtain the precise position of the weld.

[0042] By using two-level positioning, we can balance global positioning efficiency with local detection accuracy. The coarse-to-fine process reduces the amount of calculation and improves the response speed, making it suitable for industrial sites and effectively overcoming the impact of workpiece deformation and clamping deviation on positioning.

[0043] According to an embodiment of the present invention, step S110, obtaining the position of the base material and simultaneously obtaining the position of the center point of the steel pipe using a 3D scanning device, includes: S111, the 3D scanning device is used to scan the area to be polished of the structure from multiple angles to obtain point cloud data of the area to be polished; S112, using the region growing method or model matching method, segment the point cloud data of the parent material region and the point cloud data of the cylindrical surface region of the steel pipe from the point cloud data of the region to be polished; S113, based on flat plate point cloud data, the plane equation is obtained by fitting the plane using the RANSAC algorithm, and the fitted plane is the spatial attitude of the parent material; S114, Based on the point cloud data of the cylindrical surface region of the steel pipe, the equation of the central axis and the radius of the cylindrical surface are obtained by fitting the cylindrical surface fitting algorithm; S115, based on the intersection or nearest point of the central axis of the cylindrical surface and the fitting plane, obtain the initial reference center point.

[0044] In this embodiment, step S110 involves coarse workpiece positioning and steel pipe center determination based on 3D vision. A robotic arm carrying a 3D scanning module performs multi-angle scanning of the grinding position of the frame fixed on the positioner, acquiring complete point cloud data P_scan of the grinding area. The point cloud processing module then performs denoising, filtering, and downsampling preprocessing on the point cloud data P_scan. Using region growing or model matching methods, the point cloud data of the parent material area and the cylindrical surface area of ​​the steel pipe are segmented from the point cloud data P_scan.

[0045] For the point cloud data of the parent material region, a plane is fitted using the RANSAC algorithm to obtain the plane equation, which represents the spatial attitude of the parent material plate. For the point cloud data of the cylindrical surface region of the steel pipe, the equation of the central axis L_pipe and the radius R_pipe of the cylindrical surface are fitted using a cylindrical surface fitting algorithm. The intersection point or the closest point of this central axis with the fitted plane can be used to calculate an initial reference center point C_ref.

[0046] The stable geometric feature of the steel pipe's central axis, extracted from the 3D point cloud, is used as a global reference, rather than a variable specific point or surface. This reference is then fused with the weld space curve extracted from the line laser to plan the grinding trajectory. Using stable geometric features as a reference is more reliable than single-point and surface positioning. The RANSAC algorithm is highly resistant to interference and adaptable to harsh environments such as dust and oil. Combined with a vision system, it can accurately acquire workpiece geometric parameters, providing precise data for trajectory planning.

[0047] According to an embodiment of the present invention, step S120, obtaining the weld position based on the base material position using a line-scan laser, includes: S121, based on the location of the base material and the theoretical weld direction, the planned scanning path is obtained; S122, the control line laser is used to scan along the planned scanning path to obtain the two-dimensional contour lines of the weld cross-section and the base material; S123, by analyzing the cross-section of each weld and the two-dimensional contour line of the base material, the actual three-dimensional spatial trajectory point cloud data of the weld is obtained; S124 uses spatial circle fitting or spline curve fitting algorithms to smooth the actual three-dimensional spatial trajectory point cloud data of the weld seam and obtain the robot center point reference path.

[0048] In this embodiment, step S120 involves precise weld seam positioning and trajectory point extraction based on line laser. Based on the approximate position of the steel pipe obtained from coarse positioning and the theoretical weld seam orientation, a line laser scanning path is planned. This path allows the line laser instrument to move along a theoretical circular trajectory at a certain height above the weld seam. The robotic arm carries a 2D local precision measurement module, meaning the line laser instrument moves along the planned scanning path. The line laser instrument continuously acquires the two-dimensional contour lines Profile_i (i=1,2,...,N) of the weld seam cross-section and the base material pipe or plate at high frequency.

[0049] Real-time analysis is performed on the two-dimensional contour lines (Profile_i) of each weld cross-section and base material to identify characteristic abrupt change points on the contour lines, such as weld toes, weld roots, or the bottom of the bevel, forming the actual three-dimensional spatial trajectory point cloud data (Path_weld_actual) of the annular weld. Using spatial circle fitting or spline curve fitting algorithms, the actual three-dimensional spatial trajectory point cloud data (Path_weld_actual) is smoothed to generate a continuous and smooth robot center point reference path (Path_TCP_ref).

[0050] By scanning the weld seam with a line-scanning laser, the local precision measurement has high resolution and accurate data, capturing minute morphological differences in the weld seam. The fitting algorithm can make the grinding trajectory of the grinding tool continuous and smooth, avoiding robot movement jitter and providing high-precision input for subsequent grinding trajectories.

[0051] According to one embodiment of the present invention, step S200, determining the grinding trajectory based on the base material position, weld position, steel pipe radius, and base material thickness includes: S210, determine the grinding center based on the central axis of the cylindrical surface and the initial reference center point; S220: Based on each target point on the robot's center point reference path, obtain the normal plane of each target point relative to the central axis of the cylindrical surface; S230: In the normal plane of each target point relative to the central axis of the cylindrical surface, based on the geometry of the grinding wheel of the grinding tool and the preset grinding entry angle, the precise position of the center point of the grinding tool and the posture of the grinding tool are obtained, and the grinding trajectory of the robot driving the grinding tool is generated.

[0052] In this embodiment, step S200 involves planning the grinding trajectory, ensuring that the working surface of the sander's grinding wheel maintains an equidistant relationship with the theoretical cylindrical surface whose axis is the central axis equation L_pipe during grinding. The central axis equation L_pipe of the steel pipe cylindrical surface fitted in step S114 and the initial reference center point C_ref are reused. Then, a continuous trajectory is generated. For each target point on the robot center point reference path Path_TCP_ref, the normal plane of each target point relative to the central axis equation L_pipe of the cylindrical surface is calculated.

[0053] Within this plane, based on the geometry of the belt sander's grinding wheel, such as the radius (R-angle), and preset grinding entry angles, such as the forward tilt angle and the side tilt angle, the precise position of the grinding tool's center point and the grinding tool's posture are calculated. The key to the grinding tool's posture is ensuring that the grinding wheel forms a specific angle with the central axis equation L_pipe of the steel pipe's cylindrical surface.

[0054] The program iterates through all target points to generate a complete, robot-executable grinding trajectory. This program ensures that the belt sander moves in a circular motion around the steel pipe axis, rather than simply tracking the weld seam's spatial curve. The grinding trajectory is generated by the combined constraints of the workpiece's characteristic geometric axes, tool geometric parameters, and process parameters; that is, the trajectory is calculated, not taught or simply reproduced. It also ensures stable contact between the grinding wheel and the workpiece, consistent grinding morphology, and adaptability to steering frame components with different pipe diameters and plate thicknesses, demonstrating strong versatility.

[0055] According to an embodiment of the present invention, step S400, obtaining the contour of the ground area includes: After one or more grinding operations, the S410 uses a control line laser to scan the ground area along a planned scanning path to obtain the actual grinding contour point cloud data.

[0056] In this embodiment, after one or more grinding operations, the robot is re-equipped with a 2D local precision measurement module. A line laser is used to perform a high-precision scan along the ground weld area, similar to step 120, to acquire the actual grinding contour point cloud data P_machined.

[0057] By reusing the same line laser, the hardware cost of the system is reduced and the system structure is simplified. The scanning path of the line laser is matched with the grinding path, the data comparison benchmark is unified and the error is small. On-machine inspection does not require disassembling the workpiece, which can effectively shorten the inspection cycle and improve efficiency and product quality.

[0058] According to an embodiment of the present invention, step S500, obtaining the grinding trajectory pair by comparing the contour of the ground area with a set contour, includes: S510: By comparing the actual grinding contour point cloud data with the contour surface of the set contour in the same coordinate system, the normal distance from each measurement point of the actual grinding contour point cloud data to the contour surface of the set contour is obtained, and a margin distribution map is formed. S520 determines whether the allowance in all areas is within the allowable tolerance zone. If there are areas with excessive allowance, the grinding trajectory for areas with excessive allowance is obtained based on the allowance distribution map. If there are areas with negative allowance, the data is recorded and an alarm is triggered.

[0059] In this embodiment, the contour is set as the target ideal contour defined in the CAD model. The actual grinding contour point cloud data P_machined is compared with the contour surface of the target ideal contour defined in the CAD model in the same coordinate system. The normal distance from each measurement point to the contour surface of the ideal contour is calculated, and a margin distribution map is generated. The system analyzes and judges whether the margin in all areas is within the allowable tolerance zone, such as 0 to 0.3 mm. If there are areas with excessive margin, it proves that there are areas that are not properly ground within the ground area. Based on the margin distribution map, the system automatically generates a grinding trajectory only for these locally unground areas. If the margin is negative, it proves that there are areas of over-grinding within the ground area. The system records and alarms. Thus, after performing the compensation grinding operation, the inspection can be performed again as needed, forming a closed loop of measurement-comparison-compensation-reprocessing until the quality requirements are met.

[0060] The compensation decision-making system is based on a three-dimensional spatial allowance distribution map, using the CAD model as the sole quality standard to achieve digital and automated quality control. Through post-processing inspection and subsequent grinding, localized grinding improves efficiency and avoids waste. Over-grinding triggers an alarm to prevent workpiece scrapping, thus reducing costs.

[0061] According to an embodiment of the present invention, before obtaining the position of the base material, the center point position of the steel pipe, and the weld position in step S100, the method further includes: S700 performs hand-eye calibration of grinding tools, 3D scanning devices and line laser instruments, establishes a unified relative positional relationship in the tool coordinate system, and establishes a unified coordinate transformation relationship between the robot coordinate system, tool coordinate system and workpiece coordinate system; S800: Import the data information of the three-dimensional digital model of the area to be polished. The data information includes the theoretical parameter values ​​of the polished area after polishing.

[0062] In this embodiment, before step S100, system calibration and initialization are required. This involves completing the hand-eye calibration between the robot coordinate system, the tool coordinate system (i.e., the coordinate systems of the 3D scanning device, the line laser, and the belt sander), and the workpiece coordinate system, establishing a unified coordinate transformation relationship.

[0063] The precise three-dimensional CAD digital model of the structure to be ground is imported into the integrated control system. This three-dimensional digital model can provide the set contour. The model has marked information such as the theoretical weld position, the theoretical center axis of the steel pipe, the plate thickness, the pipe diameter, the target grinding contour, and the weld morphology after grinding.

[0064] Using a digital CAD model as the sole quality assessment standard, and through 3D comparison, quality control is made digital, automated, and traceable. The digital model drives the entire process to be automated and without human intervention, providing a unified theoretical benchmark for positioning, tracing, and detection. Calibration eliminates mechanical and installation errors between tools, ensuring coordinate consistency throughout the entire detection and operation process.

[0065] According to an embodiment of the present invention, after obtaining the initial reference center point based on the intersection or nearest point of the central axis of the cylindrical surface and the fitting plane in step S115, the method further includes: S116, the point cloud data of the area to be polished is registered with the data information of the three-dimensional digital model of the area to be polished by the iterative nearest point algorithm to obtain the preliminary workpiece pose transformation matrix.

[0066] In this embodiment, after step S115, the point cloud data P_scan of the area to be polished is roughly registered with the 3D CAD digital model using an iterative nearest-point algorithm to obtain a preliminary workpiece pose transformation matrix T_rough. This step initially aligns the actual workpiece coordinate system with the robot coordinate system and verifies the reliability of the identified features in step S110.

[0067] The registration of the point cloud data P_scan of the area to be polished with the 3D CAD digital model can improve the coarse positioning accuracy and reduce the subsequent fine measurement range. It can also verify the effectiveness of feature recognition, avoid incorrect positioning that would lead to polishing failure, and enable the actual workpiece to be accurately matched with the theoretical model, thereby improving the accuracy of the polishing trajectory.

[0068] According to an embodiment of the present invention, step S123, obtaining the actual three-dimensional spatial trajectory point cloud data of the weld by analyzing the cross-section of each weld and the two-dimensional contour line of the base material, includes: S1231, obtain the feature points on the two-dimensional contour line of each weld cross section and the base material; S1232, based on the two-dimensional coordinates of feature points in the tool coordinate system, combined with the robot's real-time pose, is uniformly transformed to the robot coordinate system to obtain three-dimensional spatial points. The collection of all three-dimensional spatial points forms the actual three-dimensional spatial trajectory point cloud data of the weld.

[0069] In this embodiment, the two-dimensional contour lines Profile_i of each weld cross-section and base material are analyzed in real time to identify characteristic abrupt change points on the two-dimensional contour lines, such as weld toes, weld roots, or the bottom of the bevel. The two-dimensional coordinates of the identified characteristic abrupt change points in the tool coordinate system are combined with the robot's real-time pose and uniformly transformed to the robot coordinate system to obtain a series of three-dimensional spatial points P_weld_i. The set of all three-dimensional spatial points P_weld_i constitutes the actual three-dimensional spatial trajectory point cloud data Path_weld_actual of the annular weld.

[0070] By extracting feature points, the system accurately focuses on key locations within the weld, ignoring irrelevant interference and reducing inspection errors. Unified coordinate transformation ensures accurate spatial positioning and supports trajectory planning. The point cloud fully reflects the actual weld morphology, adapting to deformed workpieces.

[0071] According to one embodiment of the present invention, the grinding trajectory ensures that when the grinding tool performs circumferential motion grinding around the axis of the steel pipe, the working surface of the grinding wheel always maintains an equidistant relationship with the theoretical cylindrical surface with the central axis of the cylindrical surface as the axis; in each segment of the grinding trajectory, the linear speed of the grinding tool, the robot feed speed, the feed amount, and the number of grinding passes are set.

[0072] In this embodiment, the grinding trajectory must ensure that when the belt sander moves circumferentially around the steel pipe axis, the working surface of the grinding wheel is equidistant from the theoretical cylindrical surface with the central axis L_pipe of the cylindrical surface as the axis. Process parameters are bound in each section of the trajectory, and the grinding tool linear speed, robot feed speed, feed amount, number of grinding passes or passes are set.

[0073] By equidistantly constraining the working surface of the grinding wheel with the theoretical cylindrical surface centered on the central axis L_pipe, the uniform thickness of the circumferential weld seam is ensured. Parameter binding guarantees process stability, consistent quality, and adaptability to different working conditions. This achieves high-precision, stable, and repeatable automated grinding.

[0074] According to one embodiment of the present invention, for each segment of the grinding trajectory, the set feed rate and feed speed are adjusted to 40% to 60% of the set feed rate and feed speed of the grinding trajectory.

[0075] In this embodiment, the planning principle of the grinding trajectory is the same as that of the grinding trajectory in step S200, but the parameters such as feed rate and feed speed are adjusted to 40% to 60% of the original parameters. In this embodiment, it can be specifically selected as 50%.

[0076] Lowering the process parameters for re-grinding avoids over-grinding and ensures the surface quality of the weld. It also allows for precise repair of local defects, improving the first-pass yield. By balancing re-grinding efficiency and quality, it also optimizes production cycle time.

[0077] Figure 3 A schematic diagram of the physical structure of an electronic device is provided. This electronic device may include a processor, a communications interface, a memory, and a communication bus, wherein the processor, communications interface, and memory communicate with each other via the communication bus. The processor can invoke logical instructions from the memory to execute the grinding method for the weld seams of the bogie frame as described in the above embodiment.

[0078] Furthermore, the logical instructions in the aforementioned memory can be implemented as software functional units and sold or used as independent products, and can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, or the part that contributes to related technologies, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0079] This invention discloses a computer program product, which includes a computer program stored on a non-transitory computer-readable storage medium. The computer program includes program instructions, and when the program instructions are executed by the computer, the computer can execute the grinding method for the bogie frame weld seam provided in the above-described method embodiments.

[0080] On the other hand, embodiments of the present invention also provide a non-transitory computer-readable storage medium storing a computer program thereon, which, when executed by a processor, is implemented to perform the grinding method for the bogie frame weld seam provided in the above embodiments.

[0081] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0082] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the parts that contribute to the related technology, can be embodied in the form of software products. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0083] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for grinding weld seams on a bogie frame, characterized in that, include: Obtain the location of the base material, the center point of the steel pipe, and the location of the weld. The grinding trajectory is determined based on the location of the base material, the location of the weld, the radius of the steel pipe, and the thickness of the base material. According to the grinding trajectory, the grinding tool is controlled to perform grinding motion with the center point of the steel pipe as the center.

2. The grinding method for the weld seams of the bogie frame according to claim 1, characterized in that, Also includes: Obtain the contour of the ground area; The grinding trajectory is obtained by comparing the contour of the ground area with a set contour. The grinding tool is controlled to perform additional grinding on the already ground area along the grinding trajectory.

3. The grinding method for the weld seams of the bogie frame according to claim 2, characterized in that, The process of obtaining the base material location and weld location includes: The position of the base material is obtained by a 3D scanning device, and the position of the center point of the steel pipe is also obtained. The weld position is obtained by line scanning laser based on the location of the base material.

4. The grinding method for the weld seams of the bogie frame according to claim 3, characterized in that, The step of obtaining the position of the base material and the center point position of the steel pipe using a 3D scanning device includes: The 3D scanning device is used to scan the area to be polished of the structure from multiple angles to obtain point cloud data of the area to be polished. Using the region growing method or model matching method, the point cloud data of the parent material region and the point cloud data of the cylindrical surface region of the steel pipe are segmented from the point cloud data of the region to be polished. Based on flat panel point cloud data, a plane equation is obtained by fitting a plane using the RANSAC algorithm. The fitted plane represents the spatial orientation of the parent material. Based on the point cloud data of the cylindrical surface region of the steel pipe, the equation of the central axis and the radius of the cylindrical surface are obtained by fitting the cylindrical surface using a cylindrical surface fitting algorithm; An initial reference center point is obtained based on the intersection or nearest point of the central axis of the cylindrical surface and the fitting plane.

5. The grinding method for the weld seams of the bogie frame according to claim 4, characterized in that, The step of obtaining the weld position using a line-scan laser based on the base material position includes: Based on the location of the base material and the theoretical weld direction, the planned scanning path is obtained; The weld cross-section and the two-dimensional contour lines of the base material are obtained by scanning along the planned scanning path using a control line laser. By analyzing the cross-section of each weld and the two-dimensional contour line of the base material, the actual three-dimensional spatial trajectory point cloud data of the weld is obtained. The actual three-dimensional spatial trajectory point cloud data of the weld is smoothed by using spatial circle fitting or spline curve fitting algorithms to obtain the robot center point reference path.

6. The grinding method for the weld seams of the bogie frame according to claim 5, characterized in that, The process of determining the grinding trajectory based on the location of the base material, the location of the weld, the radius of the steel pipe, and the thickness of the base material includes: The grinding center is determined based on the central axis of the cylindrical surface and the initial reference center point; Based on each target point on the robot center point reference path, obtain the normal plane of each target point relative to the central axis of the cylindrical surface; Within the normal plane of each target point relative to the central axis of the cylindrical surface, based on the geometry of the grinding wheel of the grinding tool and the preset grinding entry angle, the precise position of the center point of the grinding tool and the posture of the grinding tool are obtained, and the grinding trajectory executed by the robot driving the grinding tool is generated.

7. The grinding method for the weld seams of the bogie frame according to any one of claims 2 to 6, characterized in that, The process of obtaining the contour of the ground area includes: After one or more grinding operations, the ground area is scanned along the planned scanning path using a control line laser to obtain the actual grinding contour point cloud data.

8. The grinding method for the weld seams of the bogie frame according to claim 7, characterized in that, The step of obtaining a grinding trajectory pair by comparing the contour of the ground area with a set contour includes: By comparing the actual grinding contour point cloud data with the contour surface of the set contour in the same coordinate system, the normal distance from each measurement point of the actual grinding contour point cloud data to the contour surface of the set contour is obtained, forming a margin distribution map. Determine whether the allowance in all areas is within the allowable tolerance zone. If there are areas with excessive allowance, obtain the grinding trajectory for areas with excessive allowance based on the allowance distribution map. If there are areas with negative allowance, record and alarm.

9. The grinding method for the weld seams of the bogie frame according to claim 8, characterized in that, Before obtaining the location of the base material, the center point of the steel pipe, and the weld location, the method further includes: Hand-eye calibration is performed on the grinding tools, 3D scanning device and line laser instrument to establish a unified relative positional relationship in the tool coordinate system and to establish a unified coordinate transformation relationship between the robot coordinate system, tool coordinate system and workpiece coordinate system. Import the data information of the three-dimensional digital model of the area to be polished, including the theoretical parameter values ​​of the polished area after polishing.

10. The grinding method for the weld seams of the bogie frame according to claim 9, characterized in that, After obtaining the initial reference center point based on the intersection or nearest point of the central axis of the cylindrical surface and the fitting plane, the method further includes: The point cloud data of the area to be polished is registered with the data information of the three-dimensional digital model of the area to be polished by the iterative nearest point algorithm to obtain the preliminary workpiece pose transformation matrix.

11. The grinding method for the weld seams of the bogie frame according to claim 9, characterized in that, The step of analyzing the cross-section of each weld and the two-dimensional contour line of the base material to obtain the actual three-dimensional spatial trajectory point cloud data of the weld includes: Obtain feature points on the two-dimensional contour lines of each weld cross section and the base material; Based on the two-dimensional coordinates of the feature points in the tool coordinate system, combined with the robot's real-time pose, they are uniformly transformed into three-dimensional spatial points in the robot coordinate system. The set of all the three-dimensional spatial points forms the actual three-dimensional spatial trajectory point cloud data of the weld.

12. The grinding method for the weld seams of the bogie frame according to claim 9, characterized in that, The grinding trajectory ensures that when the grinding tool moves circumferentially around the axis of the steel pipe, the working surface of the grinding wheel always maintains an equidistant relationship with the theoretical cylindrical surface with the central axis of the cylindrical surface as its axis; in each segment of the grinding trajectory, the linear speed of the grinding tool, the robot feed speed, the feed amount, and the number of grinding passes are set.

13. The grinding method for the weld seams of the bogie frame according to claim 12, characterized in that, For each segment of the grinding trajectory, the feed rate and feed speed are adjusted to 40% to 60% of the set feed rate and feed speed of the grinding trajectory.

14. A grinding system for weld seams of a bogie frame, characterized in that, A grinding method applied to the weld seams of the bogie frame according to any one of claims 1 to 13, comprising: A 3D scanning device, the 3D scanning device being adapted to scan a workpiece; A line laser scanner, the line laser scanner being adapted to scan a workpiece; A grinding tool, said grinding tool being adapted to grind and polish welds; A robotic arm, which is connected to the 3D scanning device, the line laser, and the polishing tool respectively via a quick-change device, is adapted to drive the 3D scanning device, the line laser, and the polishing tool to move; A positioner, which is suitable for clamping, positioning and adjusting workpieces.

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