System and method for detecting arc extinguishing points and surface defects on the end face of an additive fusion layer

Abstract

The present application provides a kind of system and method for detecting arc extinguishing point and surface defects of additive deposition layer end face;Wherein the system includes visual inspection system, positioner workbench and positioning mark.The system is suitable for the quality monitoring of arc additive forming, when abnormal situation occurs during the additive process, leading to arc extinguishing, or during the interlayer waiting process, the visual inspection industrial robot quickly scans the deposition layer end face by line laser profiler and obtains its forming morphology, to locate the reference, after image processing, the complete deposition layer end face forming morphology is obtained and analyzed whether there is surface defect, finally the average height layer height ΔH of forming piece, additive arc starting / extinguishing point, surface defect and corresponding repair arc starting / extinguishing point world coordinates are calculated.The present application provides a kind of forming quality detection and monitoring method for arc additive process, with the advantages of non-contact detection, fast recognition speed, low equipment occupancy, few operating personnel required, less production time-consuming.

Description

Technical Field

[0001] This invention relates to the field of electric arc additive manufacturing technology, and in particular to a system and method for detecting the arc initiation and extinguishing points and surface defects on the end face of the additive cladding layer. Background Technology

[0002] Wire arc additive manufacturing (WAAM) is a process that uses an electric arc to melt and deposit metal wire layer by layer to create blanks that closely approximate the required dimensions of the final product. Compared to other metal additive manufacturing technologies, WAAM offers advantages such as lower equipment investment, higher manufacturing efficiency, lower production costs, higher material utilization, and suitability for large and complex metal components. Currently, WAAM is attracting increasing attention in the aerospace field.

[0003] With increasingly stringent product quality requirements in the aerospace industry, process quality inspection and monitoring of arc additive manufacturing products have become crucial. However, existing arc additive manufacturing technologies based on vision inspection systems combine dynamic programming algorithms with machine vision technology to measure the end face of the weld layer on the semi-finished workpiece during the interlayer waiting period of arc additive manufacturing, and then readjust the layer height by re-cutting layers, achieving dynamic automatic correction during the printing process. However, this system has shortcomings:

[0004] 1) The start / extinguish coordinates during arc additive manufacturing deviate from the start / extinguish coordinates set in the additive manufacturing program;

[0005] 2) During the process of electric arc additive manufacturing, problems such as wire blockage can lead to arc extinction. Abnormal arc extinction requires re-arcing. The world coordinates of the abnormal arc extinction point and the re-arcing point cannot be accurately and quickly obtained. Instead, the phenomenon can only be recorded manually and measured and located, which is inaccurate and inefficient.

[0006] 3) The forming quality of the weld layer end face of the formed part is inspected manually, which is prone to misjudgment and omission. Moreover, the inspection workload is large and highly repetitive, and the automatic identification of surface defects has not been achieved.

[0007] 4) When surface defects are discovered, it is impossible to obtain their world coordinate information accurately and quickly. Instead, the phenomenon can only be recorded manually and measurement and positioning work can be carried out, which is inaccurate and inefficient.

[0008] 5) After surface defects are discovered, manual grinding and repair are required. It is impossible to obtain the world coordinate information of the arc start / end point of the repair accurately and quickly. Only the phenomenon can be recorded manually and measurement and positioning work can be carried out, which is inaccurate and inefficient.

[0009] These factors have, to some extent, limited the promotion of electric arc additive manufacturing technology in product applications. Summary of the Invention

[0010] The purpose of this invention is to provide a system and method for detecting the arc initiation and extinguishing points and surface defects on the end face of the additive cladding layer. By using visual inspection technology, it can replace manual measurement and inspection, and realize the forming quality detection and monitoring of the electric arc additive manufacturing process.

[0011] To solve the above-mentioned technical problems, the technical solution of the present invention is: to provide a system for detecting the arc initiation and extinguishing points and surface defects on the end face of additive cladding layers, including a vision inspection system, a positioner worktable and positioning marks;

[0012] The vision inspection system includes an industrial robot and a line laser profilometer, wherein the line laser profilometer is mounted on the robotic arm of the industrial robot via a tooling flange.

[0013] The positioner workbench includes a positioner support arm structure, a positioner base, and a rotating platform; the rotating platform is a forming base for the part to be processed, and the base plate is clamped and fixed on the rotating platform by a fixture; the rotating platform is rotatably connected to the positioner support arm structure via a rotating shaft.

[0014] The positioning mark is installed on the positioner workbench, and its height can be adjusted to be the same as the average height of the formed part. The installation position can also be adjusted, and it is used for reference positioning in image stitching processing and coordinate calculation.

[0015] Furthermore, the relative position of the line laser profilometer and the end face of the weld layer is adjusted within the measurement range of the line laser profilometer, and the end face of the weld layer is scanned at a constant speed along the scanning path to obtain its profile, while maintaining the relative positional relationship during scanning.

[0016] Furthermore, the rotating platform can rotate around the axis from -90° to 90°, and can rotate around the center point in a 360° direction.

[0017] Another technical solution of the present invention provides a detection method using the above-described system for detecting the arc initiation and extinguishing points and surface defects on the end face of additive welded layers, comprising the following steps:

[0018] S1. Install positioning markers and scan the end face of the additive cladding layer;

[0019] S2. Image stitching and data processing of the end face morphology and contour of the weld layer;

[0020] S3. Treatment of surface defects on the end face of the weld layer;

[0021] S4. The industrial robot returns to its initial position, and a coordinate information document is generated.

[0022] Furthermore, step S1 includes:

[0023] Adjust the robotic arm of the industrial robot until the relative position of the line laser profilometer and the end face of the nth cladding layer is within the working range of the line laser profilometer; install positioning marks on the positioner's worktable, with O1 as the zero point reference of the image coordinate system, and O1's world coordinates...

[0024] When an abnormal situation occurs during additive manufacturing that causes the arc to be extinguished, or during the waiting period between layers, a scanning path is set according to the line laser width d and the shape of the end face of the cladding layer, and the scanning path intervals are the same; the end face of the nth cladding layer is scanned at a uniform speed to obtain its morphological contour.

[0025] Furthermore, step S2 includes:

[0026] The topographic contour is obtained by image stitching to obtain the complete topographic contour of the nth weld layer end face, and the presence of surface defects is analyzed; then the average height of the formed part is calculated. The height ΔH of the nth layer, and the height difference |h between the end face contours of the nth and (n-1)th layers. n -h n-1 |, with MAX(|h n -h n-1 |) is the starting point of the additive manufacturing arc (A), and its position coordinates in the image coordinate system (X) are obtained. nA Y nA ) and world coordinates Intersection points need to be excluded; MIN(|h n -h n-1 |) is the arc extinguishing point (B) of the additive manufacturing process, and its position (X) in the image coordinate system is obtained. nB Y nB ) and world coordinates

[0027] Furthermore, step S3 includes:

[0028] S3-1. Determine the type of surface defect:

[0029] When |h n -h n-1 | <0.1 indicates no overlap, starting point (C1), obtain its position coordinates (X) in the image coordinate system. nC1 Y nC1 ) and world coordinates The endpoint (C1′) is used to obtain its position coordinates in the image coordinate system (X). nC1′ Y nC1′ ) and world coordinates

[0030] |hn -h n-1 |-ΔH>0.2, excluding the additive arc initiation point A, the rest are spatter points (C2), and their image coordinate system position coordinates (X) are obtained. nC2 Y nC2 ) and world coordinates ΔH-|h n -h n-1 |>0.2, excluding the additive arc extinguishing point B, the remaining points are porosity points (C3), and their image coordinate system position coordinates (X) are obtained. nC3 Y nC3 ) and world coordinates

[0031] The breakpoints of the weld layer end face contour curve are excluded, and the edges are excluded as crack initiation points (C4). The position coordinates (X) of these breakpoints in the image coordinate system are obtained. nC4 Y nC4 ) and world coordinates The endpoint (C4′) is used to obtain its position coordinates in the image coordinate system (X). nC4′ Y nC4′ ) and world coordinates

[0032] S3-2. If the surface defect is spatter or pores, it shall be polished; if the surface defect is non-overlapping, it shall be repaired; if the surface defect is crack, it shall be polished and repaired. The arc starting / extinguishing position should avoid the starting and ending points of the crack.

[0033] S3-3. After completing the grinding and repair, repeat steps S3-1 and S3-2 to calculate the world coordinates of the starting point (A′) of each surface defect and corresponding repair. The world coordinates of the extinguishing arc point (B′) Continue until there are no surface defects on the end face of the weld layer;

[0034] S3-4. When there are no surface defects on the end face of the weld layer, calculate the average height of the formed part after grinding and processing.

[0035] Furthermore, step S4 includes:

[0036] The vision inspection industrial robot stops working and returns to its initial position. The computer generates a document containing world coordinate information of all additive start / end points, surface defects, and corresponding repair start / end points for the nth layer, and marks abnormal start / end points as records.

[0037] The beneficial effects of the system and method for detecting the arc initiation and extinguishing points and surface defects on the end face of additive welded layers provided by this invention are as follows:

[0038] 1) Automated inspection of the forming quality of the weld layer end face of the formed part enables high-precision and high-efficiency identification and location of surface defects, facilitating corresponding grinding and repair. The world coordinate information of the surface defects can be used for subsequent process improvement analysis to further improve the quality of the formed part;

[0039] 2) It can effectively record the location and world coordinate information of the arc start / end point of the formed part and the repair arc start / end point, and can mark abnormal arc start and end points to realize the quality detection and monitoring of the forming process;

[0040] 3) After the formed parts undergo non-destructive testing, internal quality problems can be linked to the actual process, which facilitates quality analysis and corresponding process improvements. Attached Figure Description

[0041] The invention will be further described below with reference to the accompanying drawings:

[0042] Figure 1 This is a schematic diagram of the structure of an arc additive manufacturing system based on vision detection according to the present invention.

[0043] Figure 2 This is a schematic diagram of the positioner's worktable.

[0044] Figure 3 This is a schematic diagram of an aluminum alloy ring-shaped structural part.

[0045] Figure 4 This is a schematic diagram of arc initiation / extinction at the end face of the weld layer of an aluminum alloy ring-shaped component. Detailed Implementation

[0046] The system and method for detecting arc initiation and extinguishing points and surface defects on the end face of additive welded layers, as proposed in this invention, will be further described in detail below with reference to the accompanying drawings and specific embodiments. The advantages and features of this invention will become clearer from the following description and claims. It should be noted that the drawings are all in a very simplified form and use non-precise ratios, and are only used to facilitate and clarify the illustration of the embodiments of this invention.

[0047] Example 1:

[0048] Figure 3 This is a schematic diagram of an aluminum alloy ring structure. The specific steps for using this invention to perform arc additive manufacturing on this aluminum alloy ring structure are as follows:

[0049] Step 1: Path planning for aluminum alloy ring structure

[0050] In this embodiment, the aluminum alloy annular structure has a wall thickness of 7mm, a bottom outer diameter R1 = 150mm, a top outer diameter R2 = 100mm, and a total height of 100mm. The center of the annular structure coincides with the center O of the positioner's worktable. The arc initiation point and arc extinguishing point are both placed at the tail blank. The first layer height is set to 2mm, the layer height is set to 1mm, and the arc initiation and extinguishing overlap distance is 4mm.

[0051] Step 2: Parameter Setting and Arc Additive Manufacturing

[0052] In this embodiment, the process mode adopted is CMT-Pluse pulse composite cold metal transition mode, with a wire feeding speed of 6m / min, a cladding speed of 10mm / s, and a high-purity argon protective gas flow rate of 15L / min. Then, the arc additive manufacturing industrial robot is used to perform arc additive manufacturing on the structural parts according to the arc additive manufacturing path obtained in step (1).

[0053] Step 3: Install positioning markers and scan the end face of the weld layer of the aluminum alloy ring structure.

[0054] In this embodiment, a total of 6 positioning markers are installed, with a spacing of 25mm between them. Using the first positioning marker O1 as a reference, world coordinates... Adjust the robotic arm of the vision inspection industrial robot until the line laser profilometer is 90mm away from the end face of the weld layer, with a line laser width of 47mm, while maintaining a constant height. After completing the nth layer of arc additive manufacturing, proceed along the line parallel to... Figure 2 The positioner AA axis is shown to perform end face scanning on the ring structure with a scanning interval of 40mm, obtaining 4 scan contour images.

[0055] Step 4: Image stitching and data processing of the weld layer end face morphology contour.

[0056] In this embodiment, four images are stitched together to obtain the complete contour of the nth weld layer end face, and the presence of surface defects (non-overlap, cracks, pores, spatter) is analyzed. Then, the average height of the formed part is calculated. The height ΔH of the nth layer, and the height difference |h| between the end face contours of the nth and (n-1)th layers. n -h n-1 |, with MAX(|h n -h n-1 |) is the starting point of the additive manufacturing arc (A), and its position coordinates in the image coordinate system (X) are obtained. nA Y nA ) and world coordinates With MIN(|h n -h n-1 |) is the arc extinguishing point (B) of the additive manufacturing process, and its position (X) in the image coordinate system is obtained. nB Y nB ) and world coordinates

[0057] Surface defects are classified according to their defect type as: |h n -h n-1 | <0.1 indicates no overlap, starting point (C1), obtain its position coordinates (X) in the image coordinate system. nC1 Y nC1 ) and world coordinates The endpoint (C1′) is used to obtain its position coordinates in the image coordinate system (X). nC1′ Y nC1′ ) and world coordinates |h n -h n-1 |-ΔH>0.2, excluding the additive arc initiation point A, the rest are spatter points (C2), and their image coordinate system position coordinates (X) are obtained. nC2 Y nC2 ) and world coordinates ΔH-|h n -h n-1 |>0.2, excluding the additive arc extinguishing point B, the remaining points are porosity points (C3), and their image coordinate system position coordinates (X) are obtained. nC3 Y nC3 ) and world coordinates The breakpoints of the weld layer end face contour curve are excluded, and the edges are excluded as crack initiation points (C4). The position coordinates (X) of these breakpoints in the image coordinate system are obtained. nC4 Y nC4 ) and world coordinates The endpoint (C4′) is used to obtain its position coordinates in the image coordinate system (X). nC4′ Y nC4′ ) and world coordinates

[0058] Step 5: Surface defect treatment of the weld layer end face

[0059] In this embodiment, if the surface defect on the end face of the weld layer is spatter or pores, it is ground; if it is not overlapped, it is repaired; if it is a crack, it is ground and repaired, and the arc start / extinguishing position is reset. After the grinding and repair are completed, steps (3) and (4) are repeated to calculate the world coordinates of the arc start point (A′) of each surface defect and the corresponding repair. The world coordinates of the extinguishing arc point (B′) Continue until there are no surface defects on the end face of the weld layer, and calculate the average height of the formed part after grinding and processing.

[0060] Step 6: The robot returns to its initial position, and a coordinate information document is generated.

[0061] In this embodiment, after the aluminum alloy ring structure reaches the required dimensions of the three-dimensional model, the arc additive manufacturing robot and the vision inspection robot stop working and return to their initial positions. The computer compiles and generates a document containing world coordinate information of all additive manufacturing start / end points, surface defects, and corresponding repair start / end points for the ring structure, and marks abnormal start / end points as records.

[0062] The contents not described in detail in this specification are prior art known to those skilled in the art. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A systematic detection method for detecting the arc initiation and extinguishing points and surface defects on the end face of additive welded layers, characterized in that, This includes a vision inspection system, a positioner worktable, and positioning markers; The vision inspection system includes an industrial robot and a line laser profilometer, wherein the line laser profilometer is mounted on the robotic arm of the industrial robot via a tooling flange. The positioner workbench includes a positioner support arm structure, a positioner base, and a rotating platform; the rotating platform is a forming base for the part to be processed, and the base plate is clamped and fixed on the rotating platform by a fixture; the rotating platform is rotatably connected to the positioner support arm structure via a rotating shaft. The positioning mark is installed on the worktable of the positioner, and its height can be adjusted to be the same as the average height of the formed part. The installation position can also be adjusted, and it is used for reference positioning in image stitching processing and coordinate calculation. The detection method for the system for detecting the arc initiation and extinguishing points and surface defects on the end face of the additive weld layer includes the following steps: S1. Install positioning markers and scan the end face of the additive cladding layer; S2. Image stitching and data processing of the end face morphology and contour of the weld layer; S3. Treatment of surface defects on the end face of the weld layer; S4. The industrial robot returns to its initial position, and a coordinate information document is generated. After non-destructive testing of the formed parts, internal quality problems can be linked to the actual process, which facilitates quality analysis and corresponding process improvements. Step S1 includes: Adjust the robotic arm of the industrial robot until the relative position of the line laser profilometer and the end face of the nth cladding layer is within the working range of the line laser profilometer; install positioning marks on the positioner's worktable, with O1 as the zero point reference of the image coordinate system, and O1's world coordinates... When an abnormal situation occurs during the additive manufacturing process, causing the arc to be extinguished, or during the waiting process between layers, the scanning path is set according to the line laser width d and the shape of the end face of the weld layer, and the scanning path interval is the same; the end face of the nth weld layer is scanned at a uniform speed to obtain its morphological contour. Step S2 includes: The topographic contour is stitched together to obtain the complete topographic contour of the nth weld layer end face, and the presence of surface defects is analyzed; then the average height of the formed part is calculated. The height ΔH of the nth layer, and the height difference |h between the end face contours of the nth and (n-1)th layers. n -h n-1 |, with MAX(|h n -h n-1 |) is the starting point of the additive manufacturing arc (A), and its position coordinates in the image coordinate system (X) are obtained. nA Y nA ) and world coordinates Intersection points need to be excluded; MIN(|h n -h n-1 |) is the arc extinguishing point (B) of the additive manufacturing process, and its position (X) in the image coordinate system is obtained. nB Y nB ) and world coordinates Step S3 includes: S3-1. Determine the type of surface defect: When |h n -h n-1 | <0.1 indicates no overlap, starting point (C1), obtain its position coordinates (X) in the image coordinate system. nC1 Y nC1 ) and world coordinates The endpoint (C1') yields its position coordinates in the image coordinate system (X). nC1' Y nC1' ) and world coordinates |h n -h n-1 |-ΔH>0.2, excluding the additive arc initiation point A, the rest are spatter points (C2), and their image coordinate system position coordinates (X) are obtained. nC2 Y nC2 ) and world coordinates ΔH-|h n -h n-1 |>0.2, excluding the additive arc extinguishing point B, the remaining points are porosity points (C3), and their image coordinate system position coordinates (X) are obtained. nC3 Y nC3 ) and world coordinates The breakpoints of the weld layer end face contour curve are excluded, and the edges are excluded as crack initiation points (C4). The position coordinates (X) of these breakpoints in the image coordinate system are obtained. nC4 Y nC4 ) and world coordinates The endpoint (C4') yields its position coordinates in the image coordinate system (X). nC4' Y nC4' ) and world coordinates S3-2. If the surface defect is spatter or pores, it shall be polished; if the surface defect is non-overlapping, it shall be repaired; if the surface defect is crack, it shall be polished and repaired. The arc starting / extinguishing position should avoid the starting and ending points of the crack. S3-3. After completing the grinding and repair, repeat steps S3-1 and S3-2 to calculate the world coordinates of the starting point (A') of each surface defect and corresponding repair. World coordinates of the extinguishing arc point (B') Continue until there are no surface defects on the end face of the weld layer; S3-4. When there are no surface defects on the end face of the weld layer, calculate the average height of the formed part after grinding and processing. Step S4 includes: The vision inspection industrial robot stops working and returns to its initial position. The computer generates a document containing world coordinate information of all additive start / end points, surface defects, and corresponding repair start / end points for the nth layer, and marks abnormal start / end points as records.

2. The detection method of the system for detecting the arc initiation and extinguishing points and surface defects on the end face of the additive weld layer as described in claim 1, characterized in that, The relative position of the line laser profilometer and the end face of the weld layer is adjusted within the measurement range of the line laser profilometer. The end face of the weld layer is scanned at a constant speed along the scanning path to obtain its profile, while maintaining the relative positional relationship during scanning.

3. The detection method of the system for detecting the arc initiation and extinguishing points and surface defects on the end face of the additive weld layer as described in claim 2, characterized in that, The rotating platform can rotate around the axis from -90° to 90°, and can rotate around the center point in a 360° direction.

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