Variable Thickness Ring Laser-Arc Complementary Fused Wire Additive Manufacturing Device and Method

Abstract

This invention discloses a ring-shaped laser-arc complementary fused wire additive manufacturing device and method for variable thickness structures, relating to the field of additive manufacturing technology. Specifically, it implements zoning processing for variable thickness structures, dividing the thick-walled region into a primary region and a secondary region. The primary region is formed by an electric arc, the secondary region by a laser-arc composite, and the thin-walled region by a laser. During each layer of additive manufacturing, surface defects are detected by a visual recognition system, and the defects are filled using three quarter laser modes. The above steps are repeated until the workpiece is formed, and then laser additive filling is performed on the outer surface of the workpiece. Overall, by leveraging the complementary advantages of laser and electric arc heat sources and the precise control of the ring laser, both additive manufacturing efficiency and forming accuracy are balanced, ultimately obtaining additive products with excellent forming quality and high precision.

Description

Technical Field

[0001] This invention belongs to the field of additive manufacturing technology, specifically relating to a variable thickness structure ring laser-arc complementary fused wire additive manufacturing device and method. Background Technology

[0002] Existing additive manufacturing technologies include two main categories: laser additive manufacturing and arc additive manufacturing. While laser additive manufacturing offers high forming accuracy, its concentrated energy density results in low deposition efficiency in thick-walled areas. Arc additive manufacturing, on the other hand, boasts higher deposition efficiency and can rapidly deposit material in thick-walled regions, but its heat dissipation and large heat input can easily lead to residual stress and deformation in components, and its lower forming accuracy makes it unsuitable for the high-precision manufacturing requirements of thin-walled areas. Therefore, how to utilize laser-arc complementary additive manufacturing to achieve integrated forming of variable-thickness structures has become one of the challenges facing the additive manufacturing field.

[0003] To address the above issues, existing patent CN109175364A discloses a laser additive manufacturing device and its additive manufacturing method, which can solve defects such as element segregation, gas entrapment, uneven microstructure, and thermal stress concentration within the molten pool. However, this method is not suitable for integrated forming of variable thickness structures and lacks a real-time surface morphology recognition and feedback mechanism, which can easily lead to the accumulation of interlayer defects and affect the mechanical properties of the component. Existing patent CN108326430A discloses a laser-arc composite partitioned additive manufacturing process and equipment, combining laser additive manufacturing, arc additive manufacturing, and a lateral wire feeding method to form a new additive manufacturing system. However, this invention only discloses a system combining multiple processes and does not explain the specific means of laser-arc complementary additive manufacturing, nor does it address defect filling. Summary of the Invention

[0004] The purpose of this invention is to provide a variable thickness structure annular laser-arc complementary fused wire additive manufacturing device and method to solve the above-mentioned problems.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a variable thickness structure ring laser-arc complementary fused wire additive manufacturing method, the specific steps of which are as follows:

[0006] S1. Based on the design drawings of the variable thickness structure and combined with the criteria of structural stiffness and process efficiency, the area is divided and the additive manufacturing path is planned. Then, the data of the divided area and the planned additive manufacturing path are entered into the control system to allocate the work area and set the safety distance.

[0007] S2, three quadrature laser modes are set, and the laser coaxial filament additive manufacturing system is controlled by the control system to achieve mode switching;

[0008] S3, perform surface cleaning on the substrate of the workpiece to be additively processed; fix the cleaned substrate on the positioning fixture of the substrate; set the additive process parameters through the control system;

[0009] S4, based on the zoning planning results of S1, controls the synchronous start of the laser coaxial filament additive manufacturing system and the electric arc additive manufacturing system to perform additive manufacturing according to the preset process; based on the linkage control of the six-axis robot and the six-axis robot II, the coordination of the two systems is ensured and the interference of operations is avoided;

[0010] S5. After each additive manufacturing operation is completed, the control system activates the additive manufacturing surface vision recognition system to perform a comprehensive scan of the current additive layer surface and transmits the initial data to the control system. The control system preprocesses the scanned data to obtain a 3D point cloud, compares it with the preset CAD model, sets a deviation threshold to filter defect points, calculates the geometric center coordinates of the defects, and defines the defect size along the additive direction as length D. C The defect dimension perpendicular to the additive direction is width D. K The final output includes the size, coordinates, and shape data of the defect.

[0011] S6, based on the surface defect data output by S5, adapts the corresponding filling strategy; given the irregular shape of the defects and the differences in defect filling capabilities among the three laser modes, the applicable ranges of the three modes are divided according to the filling width of the three laser modes: D K When D1 < D1, use mode c; when D1 < D K <D2 uses pattern b, D K >D2 uses mode a; after each range of defect filling is completed, the laser coaxial filament additive system's quarter laser spacing is adjusted through the control system, and the laser mode is switched to perform the next range of defect filling; after the defect filling is completed, the additive surface is scanned again to confirm that the surface roughness meets the additive requirements;

[0012] S7. Repeat steps S4-S6 until the additive manufacturing operation is completed; the control system controls the laser coaxial filament additive manufacturing system to fill the outer surface of the workpiece with laser additive manufacturing; after the workpiece cools down, the additive manufacturing surface vision recognition system is restarted to scan and inspect the entire workpiece to confirm that the forming quality of the workpiece meets the design requirements, thus completing the entire additive manufacturing process.

[0013] Preferably, the regions in the division area in S1 specifically include a thin-walled region (wall thickness < 5 mm), corresponding to laser additive manufacturing; a first-level thick-walled region (wall thickness ≥ 10 mm), corresponding to electric arc additive manufacturing; and a second-level thick-walled region (wall thickness 5-10 mm), corresponding to laser-electric arc composite additive manufacturing.

[0014] Preferably, in step S1, the variable thickness structure design drawing is imported using Slic3r slicing software to complete the workpiece layer slicing. The slicing layer thickness is set to h, and the slicing layer thickness h is matched with the workpiece wall thickness t to ensure the additive forming quality of each layer. At the same time, the wire feeding speed is precisely set in conjunction with the slicing layer thickness h. With welding speed To ensure precise matching between wire feeding speed, welding speed, slice layer thickness, and workpiece wall thickness; for slices involving only a single area, a Zig-Zag additive path is used, which employs a reciprocating alternating scanning method; for slices involving multiple areas, a unidirectional parallel line additive path is used, and each path must pass through multiple different areas until the additive layer is completed.

[0015] Preferably, the three quadrature laser modes in S2 are: mode a, in which the two beams of the quadrature laser are elongated along the direction perpendicular to the additive manufacturing direction; mode b, in which the two diagonals of the quadrature laser are parallel to the direction perpendicular to the additive manufacturing direction; and mode c, in which the two beams of the quadrature laser are elongated along the additive manufacturing direction.

[0016] Preferably, the detailed process of S5 is as follows:

[0017] S51: After each additive manufacturing layer is completed, the control system activates the additive manufacturing surface vision recognition system, which uses a scanner to perform a full scan of the current additive layer surface, with a scanning step size of [missing information]. With slice thickness Adaptation, satisfaction To ensure no area is missed during the scan, the initial scan data is transmitted to the control system. The control system preprocesses the scan data, first removing noise interference using a Gaussian filtering algorithm to obtain the accuracy of the filtered point cloud data. .

[0018] S52: After preprocessing, a clean 3D point cloud is obtained. This is then imported into Geomagic point cloud processing software. The 3D point cloud is aligned and compared with a preset CAD model. Arbitrary points in the point cloud are defined. The three-dimensional coordinates are The corresponding 3D coordinates of the points on the CAD model are Then the deviation at that point Set deviation threshold Its relationship with slice thickness The quantitative relationship is =0.15h, when > When this point is identified, it is determined to be a defect point;

[0019] S53: Independent defect point cloud clusters are filtered and segmented using software; a single defect point cloud cluster is defined as containing... There are 3 defect points, and the geometric center coordinates of the defect cluster are given as follows: ;

[0020] S54: Construct a central axis passing through the geometric center coordinates and parallel to the additive direction. Define the defect size along the central axis as length D. C The defect dimension perpendicular to the central axis is width D. K Output the size of the defect (D) C D K Geometric center coordinates and morphological data.

[0021] Preferably, the detailed process of S6 is as follows:

[0022] S61: The control system receives the defect size, coordinates, and shape data output from step S5, and extracts the defect width D. K Parameters; then, based on the differences in additive width corresponding to the three four-part laser modes, the additive width and defect width D of the laser mode are established. K The adaptation relationship is set by defining two thresholds, D1 and D2, to determine the defect width D. K It is divided into three different adaptation ranges.

[0023] S62: Based on the laser mode obtained by the above matching, the control system sends a precise control command to the laser coaxial filament additive manufacturing system to adjust the angle of the adjustable mirror in the laser mirror group, thereby changing the spacing of the ring laser beam and realizing precise switching of the laser mode; at the same time, the laser power and the wire feeding speed are adjusted synchronously, wherein the laser power is filled to no less than the laser power of the laser filament additive manufacturing in step S4, and the wire feeding speed is reduced synchronously with the laser power to ensure that the filling layer thickness is controlled within the range of 0.1mm-0.3mm.

[0024] S63: Laser-coaxial fused wire additive manufacturing system based on defect geometric center coordinates Under the coordinated control of a six-axis robot, it moves to the location of the defect and performs defect filling operations according to the matched laser pattern, with the filling path along the defect length D. C Uniform scanning in the direction.

[0025] S64: If a single defect point cloud cluster has multiple segments with different D K For defect areas of a certain width, then according to D K The thresholds are matched with the corresponding laser modes in descending order. After each defect filling operation of a certain width is completed, the mode switching and parameter adjustment operation in step S62 is repeated, and then the filling operation of the next width is performed until the filling work of the defect point cloud cluster is completed.

[0026] S65: After a single defect or all defects are filled, the control system restarts the additive manufacturing surface vision recognition system to perform a local scan of the filled area. The point cloud data obtained from the scan is compared with the preset CAD model to verify whether the surface deviation of the filled area is less than the preset threshold and to confirm that the surface roughness meets the additive design requirements. If the filling quality does not meet the standards, the steps S61-S64 are repeated for a second filling until the design requirements are met.

[0027] Preferably, the adjustable reflector in S62 has an angle adjustment range of -15° to 15° and an adjustment accuracy of 0.1°. The angle change of the reflector directly determines the spacing of the ring laser beams: when the reflector angle increases, the angle between the emission directions of the sub-laser beams increases, and the spacing of the ring laser beams increases accordingly; when the reflector angle decreases, the spacing of the ring laser beams decreases. Different additive filling strategies can be adapted through the above angle adjustment.

[0028] A variable thickness structure ring-shaped laser-arc complementary fused wire additive manufacturing device, comprising: a laser coaxial fused wire additive manufacturing system, an arc additive manufacturing system, a control system, and a visual recognition system for additive manufacturing surfaces;

[0029] The laser coaxial wire melting additive manufacturing system includes a wire feeder, a laser, an optical fiber, a six-axis robot, and a laser mirror assembly. The laser is controlled by the six-axis robot, and its laser power is adjusted and its laser beam is controlled by the control system. The laser beam is transmitted to the laser mirror assembly through the optical fiber, and four ring laser beams are formed under the action of the laser mirror assembly. The ring laser beams are used to melt the welding wire to complete the additive manufacturing process.

[0030] The electric arc additive manufacturing system includes an electric arc power source, a wire feeder, a six-axis robot, and a welding torch. It completes the additive manufacturing process by melting the welding wire with an electric arc.

[0031] The control system precisely regulates each system to perform additive manufacturing operations based on the zoning processing results of the variable thickness structure. At the same time, based on the surface defect data fed back by the additive manufacturing surface vision recognition system, the system adjusts the spacing of the ring laser beams of the laser coaxial filament additive manufacturing system and uses three laser modes to perform additive filling operations.

[0032] The additive manufacturing surface vision recognition system includes a laser additive scanner and an arc additive scanner, which are fixed on both sides of the laser welding gun and the arc welding gun, respectively. They scan the additive surface synchronously with the additive process and transmit the obtained morphology data to the control system. After processing by the control system, the surface accuracy data after additive manufacturing is obtained. The control system implements the corresponding filling strategy based on the surface accuracy data.

[0033] The technical effects and advantages of this invention are as follows: This invention implements a zoned processing for structures with varying thicknesses. The thick-walled region is divided into a primary region and a secondary region. The primary region is formed by an electric arc, the secondary region is formed by a laser-electric arc composite, and the thin-walled region is formed by a laser. During each layer of additive manufacturing, surface defects are detected by a visual recognition system, and the defects are filled using three quarter laser modes. The above steps are repeated until the workpiece is formed, and then laser additive filling is performed on the outer surface of the workpiece. Overall, by leveraging the complementary advantages of laser and electric arc heat sources and the precise control of the ring laser, both additive manufacturing efficiency and forming accuracy are balanced, ultimately resulting in additive products with excellent forming quality and high precision. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the overall structure of the device according to an embodiment of the present invention;

[0035] Figure 2 This is a schematic diagram of the laser mirror assembly of the present invention;

[0036] Figure 3 This is a schematic diagram of the annular laser beam spacing under the three modes of the present invention;

[0037] Figure 4 This is a flowchart illustrating an embodiment of the present invention.

[0038] In the diagram: 1. Laser coaxial fused wire additive manufacturing system; 10. Welding wire; 11. Wire feeder 1; 12. Laser; 13. Optical fiber; 14. Six-axis robot;

[0039] 2. Arc additive manufacturing system; 20. Arc power supply; 21. Wire feeder II; 22. Six-axis robot II; 23. Welding torch;

[0040] 3. Control system;

[0041] 4. Additive manufacturing surface vision recognition system; 41. Laser additive scanner; 42. Arc additive scanner; 5. Laser mirror assembly; 51. Housing; 52. Prism beam splitter; 53. Focusing lens; 54. Adjustable reflector;

[0042] 6. Fixture; 7. Substrate; 8. Worktable. Detailed Implementation

[0043] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] This invention provides, for example Figures 1-4The variable thickness structure annular laser-arc complementary fused wire additive manufacturing device and method shown herein, the device comprising:

[0045] like Figure 1 A variable thickness structure ring laser-arc complementary fused wire additive manufacturing device is used to adapt to additive manufacturing of variable thickness structures. The device includes: a laser coaxial fused wire additive manufacturing system 1, an arc additive manufacturing system 2, a control system 3, and an additive manufacturing surface vision recognition system 4.

[0046] The laser coaxial welding wire additive manufacturing system 1 includes a wire feeder 11, a laser 12, an optical fiber 13, a six-axis robot 14, and a laser mirror group 5. The laser 12 is controlled by the six-axis robot 14, and its laser power is adjusted and controlled by the control system 3 to emit a laser beam. The laser beam is transmitted to the laser mirror group 5 through the optical fiber 13. Under the action of the laser mirror group 5, four ring laser beams are formed. The welding wire 10 is melted by the ring laser beams to complete the additive manufacturing process.

[0047] The electric arc additive manufacturing system 2 includes an electric arc power source 20, a wire feeder 21, a six-axis robot 22, and a welding torch 23, which completes the additive manufacturing process by melting the welding wire with an electric arc.

[0048] The control system 3 can precisely control each system to perform additive manufacturing operations based on the zoning processing results of the variable thickness structure; at the same time, based on the surface defect data fed back by the additive manufacturing surface vision recognition system 4, the spacing of the annular laser beam of the laser coaxial filament additive manufacturing system 1 is adjusted, and additive filling operations are performed using three laser modes.

[0049] The additive manufacturing surface vision recognition system 4 includes a laser additive scanner 41 and an arc additive scanner 42, which are fixed on both sides of the laser welding gun and the arc welding gun, respectively. They scan the additive surface synchronously with the additive process and transmit the obtained morphology data to the control system 3. After processing by the control system 3, the surface accuracy data after additive manufacturing is obtained. The control system 3 implements the corresponding filling strategy based on the surface accuracy data.

[0050] A variable thickness ring-shaped laser-arc complementary fused wire additive manufacturing method includes the following steps:

[0051] S1: Based on the design drawings of the variable thickness structure, and combined with the criteria of structural stiffness and process efficiency, the area is divided and the additive manufacturing path is planned. Then, the data of the divided area and the planned additive manufacturing path are entered into the control system to allocate the work area and set the safety distance.

[0052] The threshold for the boundary between thin-walled and thick-walled regions is determined using the structural bending stiffness calculation formula:

[0053] (1)

[0054] in The structural bending stiffness (N·m); t represents the material's elastic modulus (MPa); t represents the wall thickness (m). Poisson's ratio; The minimum allowable stiffness (N·m) for the project can be calculated. The lower limit of the wall thickness t can be obtained. Combining the rounding principle of the project, 5mm is determined as the threshold for dividing the thin-walled region and the thick-walled region.

[0055] Determination of grading thresholds for thick-walled regions: Establishment of a process efficiency adaptation criterion equation:

[0056] (2)

[0057] When t≥10mm: The deposition efficiency requirement for thick-walled regions is much higher than the accuracy requirement. The cladding layer thickness and scanning speed of arc additive manufacturing can be matched to the deposition of large-walled regions. =15cm 3 / min (no obvious defects) =1cm 3 ( / min), η=15≥1.2, the efficiency is optimal; if laser-arc composite is used at this time, the high laser energy density will lead to thermal input redundancy, which will increase defects. As η increases, η decreases.

[0058] When 5mm < t < 10mm: medium wall thickness, efficiency and accuracy need to be balanced. Arc additive manufacturing alone will result in poor wall thickness control accuracy and increased defect rate due to heat dissipation. Increased to 3-4cm 3 / min), η is reduced to 4-5; while laser-arc composite additive manufacturing achieves precise laser shape control and efficient arc deposition. =8cm 3 / min, =1cm 3 With a processing speed of / min and η=8≥1.2, balancing efficiency and forming accuracy, this is the optimal process for this range. A threshold of 10mm is determined as the boundary between the first-level and second-level thick-walled regions, adapting to the process characteristics of arc additive manufacturing and laser-arc composite additive manufacturing. This ensures structural integrity under load and avoids plastic deformation, brittle fracture, and fatigue failure. The wall thickness range and corresponding additive manufacturing process for each region are clearly defined: thin-walled regions (<5mm) use laser additive manufacturing; first-level thick-walled regions (≥10mm) use arc additive manufacturing; and second-level thick-walled regions (5-10mm) use laser-arc composite additive manufacturing. The above partitioning data is entered into the control system, which then allocates the operating areas for each additive manufacturing system and sets the safe operating distances for each system.

[0059] Additive manufacturing path planning: Import the variable thickness structure design drawing into Slic3r slicing software, complete the workpiece layer slicing, and set the slice layer thickness to [value missing]. (Unit: mm), slice thickness With workpiece wall thickness Adaptation ensures the quality of each additive manufacturing layer; while also considering the slice layer thickness. Precisely set the wire feeding speed With welding speed The three satisfy the following quantitative relationship:

[0060] (3)

[0061] (4)

[0062] in, The unit is m / min. The unit is mm / s, and the slice thickness is... The adjustment range is 0.2-0.8mm, and it is related to the workpiece wall thickness. satisfy To ensure precise matching between wire feed speed, welding speed, slice layer thickness, and workpiece wall thickness; for slices involving only a single area, a Zig-Zag additive path is used, employing a reciprocating alternating scanning method; for slices involving multiple areas, a unidirectional parallel line additive path is used, with each path traversing multiple different areas until the additive layer is completed. This path scans at a uniform speed in the same direction, with different additive widths in each area, satisfying the following relationship:

[0063] (5)

[0064] in, Indicates the additive width. The coefficients represent the different coefficients for the three additive manufacturing methods. Indicates the wire feeding speed. Indicates the welding speed.

[0065] S2: Laser mode setting, three quadrant laser modes are set, and the control system 3 controls the laser coaxial fuse additive system 1 to switch modes: mode a, the two beams of the quadrant are lengthened along the direction perpendicular to the additive direction; mode b, the two diagonals of the quadrant are parallel to the direction perpendicular to the additive direction; mode c, the two beams of the quadrant are lengthened along the additive direction.

[0066] S3: Pre-processing: Clean the surface of the substrate of the workpiece to be additively processed; fix the cleaned substrate onto the positioning fixture 6 of the substrate 7; set the additive process parameters through the control system 3.

[0067] S4: Additive manufacturing operation. According to the zoning planning results of S1, the control system 3 controls the laser coaxial filament additive manufacturing system 1 and the electric arc additive manufacturing system 2 to start synchronously and perform additive manufacturing according to the preset process: electric arc additive manufacturing is performed in the first-level area, laser-electric arc composite additive manufacturing is performed in the second-level area, and laser filament additive manufacturing is performed in the thin-walled area. Based on the linkage control of the six-axis robot 14 and the six-axis robot 22, the coordination of the two systems is ensured and the operation interference is avoided.

[0068] S5: After each additive manufacturing layer is completed, the control system 3 activates the additive manufacturing surface vision recognition system 4, which uses a scanner to perform a full scan of the current additive layer surface, with a scanning step distance of [missing information]. (Unit: mm) and slice thickness Adaptation, satisfaction To ensure no area is missed during the scan, the initial scan data is transmitted to control system 3. Control system 3 preprocesses the scan data, first removing noise interference using a Gaussian filtering algorithm, thus improving the accuracy of the filtered point cloud data. (Unit: mm) satisfies the following formula:

[0069] (6)

[0070] After preprocessing, a clean 3D point cloud is obtained. This point cloud is then imported into Geomagic point cloud processing software. The 3D point cloud is aligned and compared with a preset CAD model, and arbitrary points in the point cloud are defined. The three-dimensional coordinates are The corresponding 3D coordinates of the points on the CAD model are Then the deviation at that point (Unit: mm) The calculation is as follows:

[0071] (7)

[0072] Set deviation threshold (Unit: mm), which is related to the thickness of the slice layer. The quantitative relationship is =0.15h, when > When this point is identified, it is determined to be a defect point;

[0073] The software filters and segments individual defect point cloud clusters, defining each defect point cloud cluster as containing... The geometric center coordinates of the defect cluster are: [Number] defect points. (Unit: mm) The calculation is as follows:

[0074] (8)

[0075] Construct a central axis passing through the geometric center coordinates and parallel to the additive direction (X-axis direction), and define the defect size along the central axis as length D. C (Unit: mm) The defect dimension perpendicular to the central axis is the width D. K Output the size of the defect (D) C D K Geometric center coordinates and morphological data.

[0076] S6: Control system 3 receives the defect size, coordinates, and shape data output from step S5, and extracts the defect width D. K Parameters; Derivation of defect width threshold based on laser mode forming characteristics; Control system 3 derives defect width D based on the spot shape, cladding deposition width, energy distribution characteristics, and defect filling accuracy adaptability of three quadrant laser modes. K The threshold for division is determined, and then the additive width differences corresponding to the three four-part laser modes (mode a, mode b, and mode c) are derived according to formulas (3), (4), and (5). The additive width of the laser mode and the defect width D are established. K The adaptation relationship is set by defining two thresholds, D1 and D2, to determine the defect width D. K It is divided into three different adaptation ranges.

[0077] According to the laser mode obtained by matching above, the control system 3 sends a precise control command to the laser coaxial filament additive manufacturing system 1 to adjust the angle of the adjustable reflector 54 in the laser mirror group 5, thereby changing the spacing of the ring laser beam and realizing precise switching of the laser mode; at the same time, the laser power and the wire feeding speed are adjusted synchronously, wherein the laser power is filled to no less than the laser power of laser filament additive manufacturing in step S5, and the wire feeding speed is reduced synchronously with the laser power to ensure that the filling layer thickness is controlled within the range of 0.1mm-0.3mm.

[0078] Laser coaxial filament additive manufacturing system 1 based on defect geometric center coordinates Under the linkage control of the six-axis robot 14, it moves to the location of the defect and performs the defect filling operation according to the matched laser pattern. The filling path is along the defect length D. C Uniform scanning in the direction.

[0079] If a single defect point cloud cluster has multiple segments with different D K For defect areas of a certain width, then according to D K The thresholds are matched with the corresponding laser modes in descending order. After each defect filling of a width range is completed, the above steps of mode switching and parameter adjustment are repeated before the filling operation of the next width range is performed until the filling work of the defect point cloud cluster is completed.

[0080] After a single defect or all defects are filled, the control system 3 restarts the additive manufacturing surface vision recognition system 4 to perform a local scan of the filled area. The point cloud data obtained from the scan is compared with the preset CAD model to verify whether the surface deviation of the filled area is less than the preset threshold and to confirm that the surface roughness meets the additive design requirements. If the filling quality does not meet the standards, the above steps are repeated for a second filling until the design requirements are met.

[0081] S7: Finished product forming, repeat steps S4-S6 until the additive manufacturing operation is completed; control system 3 controls laser coaxial filament additive system 1 to fill the outer surface of the workpiece with laser additive manufacturing; after the workpiece cools down, the additive manufacturing surface vision recognition system 4 is restarted to scan and inspect the entire workpiece to confirm that the forming quality of the workpiece meets the design requirements, and the entire additive manufacturing process is completed. Specific Implementation

[0082] This embodiment uses a titanium alloy TC4 variable thickness frame component commonly used in the aerospace field as the additive manufacturing object. The component is an overall ring-shaped frame structure with a thin-walled region of 3mm, a secondary thick-walled region of 7mm, and a primary thick-walled region of 12mm. The overall dimensions of the component are Φ500mm × 200mm. The requirements are a surface roughness Ra ≤ 3.2μm, dimensional accuracy ±0.2mm, and bending stiffness not less than 800N・m after forming. This embodiment uses the variable thickness structure ring laser-arc complementary fused wire additive manufacturing device and method described in this invention to complete the additive manufacturing of this component. The detailed implementation process is as follows.

[0083] The additive manufacturing apparatus used in this implementation case includes a laser coaxial wire welding additive manufacturing system 1, an arc additive manufacturing system 2, a control system 3, and an additive manufacturing surface vision recognition system 4. The supporting substrate 7 is a TC4 titanium alloy substrate, the positioning fixture 6 is a pneumatic self-centering fixture, and the welding wire 10 is a φ1.2mm TC4 titanium alloy solid welding wire. The laser 12 is a fiber laser with a rated power of 3000W; the wire feeder 11 has a wire feeding accuracy of ±0.1m / min; the six-axis robot 14 has a repeatability accuracy of ±0.05mm; the laser mirror group 5 includes a four-prism beam splitter 52 with a beam splitting ratio of 1:1:1:1, and an adjustable reflector 54 with an angle adjustment accuracy calibrated to 0.1°, an initial angle set to 0°, and an initial spot spacing of 5mm for the ring laser beam.

[0084] Arc power supply 20 is a pulsed MIG arc power supply with a rated output current of 500A; wire feeder 21 is the same as wire feeder 1 of the laser coaxial wire melting additive manufacturing system; six-axis robot 22 is the same as robot of the laser coaxial wire melting additive manufacturing system; welding torch 23 is a water-cooled MIG welding torch with the nozzle distance from the workpiece initially set to 10mm.

[0085] Both the laser additive scanner 41 and the arc additive scanner 42 are line laser scanners with a scanning accuracy of ±0.01mm and a scanning frequency of 50Hz. The scanners are fixed on both sides of the laser welding gun and the arc welding gun respectively, with a spacing of 15mm, to ensure that the scanning is unobstructed.

[0086] Control system parameter initialization: Set the TC4 titanium alloy material parameters (elastic modulus E=110GPa, Poisson's ratio) to the specified parameters. =0.34), component design drawing input control system 3, preset Gaussian filter algorithm parameters, Geomagic point cloud processing software alignment comparison parameters, set the defect filling layer thickness range of 0.1mm-0.3mm, and the surface roughness qualified threshold Ra≤3.2μm.

[0087] Partition threshold verification: based on the structural bending stiffness formula Substitute the TC4 material parameters and the minimum allowable stiffness for engineering use. =800 N·m, the lower limit of the wall thickness is calculated to be 4.2 mm. Based on the rounding principle in engineering, 5 mm is determined as the boundary threshold between the thin-walled and thick-walled regions. According to the process efficiency adaptation criterion equation... Process testing has verified that when using arc additive manufacturing in a 12mm thick-walled area, =15cm³ / min, =1cm³ / min =15; When using laser-arc composite additive manufacturing in a 7mm thick-walled area =8cm³ / min, =1cm³ / min =8, all of which meet the efficiency requirements. Therefore, 10mm is determined as the boundary threshold between the first and second level thick-walled regions.

[0088] The component is divided into a thin-walled region (3mm, laser-fused wire additive manufacturing), a thick-walled secondary region (7mm, laser-arc composite additive manufacturing), and a thick-walled primary region (12mm, arc additive manufacturing). The coordinate data of the regions are entered into the control system 3. The operating range of the laser coaxial fused wire additive manufacturing system is allocated to the thin-walled region + the thick-walled secondary region, and the operating range of the arc additive manufacturing system is allocated to the thick-walled primary region + the thick-walled secondary region. The safe distance between the two systems is set to 5mm to avoid interference.

[0089] The component's CAD design drawings were imported using Slic3r slicing software. The slicing layer thickness h was adjusted according to the wall thickness. Based on h=0.08t, the following values ​​were calculated: h=0.24mm for thin-walled areas, h=0.56mm for secondary thick-walled areas, and h=0.96mm for primary thick-walled areas. Since the slicing layer thickness adjustment range is 0.2-0.8mm, h=0.8mm was used for primary thick-walled areas, h=0.2mm for thin-walled areas, and h=0.6mm for secondary thick-walled areas. Slicing was then performed in three layers with thicknesses of 0.2mm, 0.6mm, and 0.8mm.

[0090] Calculation of wire feed speed and welding speed: based on the formula , Calculate the process parameters for each region:

[0091] Thin-walled region (h=0.2mm): =1.8m / min, =0.36mm / s;

[0092] Thick-walled secondary region (h=0.6mm): =2.4 m / min, =0.68mm / s;

[0093] Thick-walled primary region (h=0.8mm): =2.7 m / min, =0.84mm / s.

[0094] Additive path design: For sections where a single layer slice involves only a single region (such as a pure thin-walled section or a pure thick-walled primary section), a Zig-Zag reciprocating alternating scanning path is used with a scanning interval of 0.8 mm. For sections where a single layer slice involves two or more regions (such as a thin-walled-thick-walled secondary transition section or a thick-walled secondary-thick-walled primary transition section), a unidirectional parallel line scanning path is used. The path scans at a uniform speed along the radial direction of the component, and each path passes through different regions. The additive width is calculated according to... Calculations, including laser additive manufacturing =0.6, arc additive manufacturing =1.2, Laser-Arc Composite Additive =0.9.

[0095] The control system 3 presets three quadrature laser modes to complete the mode switching calibration:

[0096] Mode a: Adjust the adjustable reflector from 54° to +5° to elongate the two beams of the four-way beam along the direction perpendicular to the additive manufacturing process, and adjust the beam spacing to 8mm;

[0097] Mode b: Adjust the adjustable reflector from 54° to 0°, so that the two diagonals of the beam splitter are parallel to the direction perpendicular to the additive manufacturing direction, and the beam spacing is kept at 5mm.

[0098] Mode c: Adjust the angle of the adjustable mirror 54 to -5° to lengthen the two beams of the four beams along the additive direction and adjust the beam spacing to 3mm; the control system 3 stores the mirror group angle and beam spacing parameters of the three modes to achieve one-click switching.

[0099] Surface treatment of the TC4 titanium alloy substrate to be added: use sandpaper to polish and remove the surface oxide scale, then use anhydrous ethanol for ultrasonic cleaning for 15 minutes to remove oil and impurities, and let it dry for later use.

[0100] The cleaned substrate is fixed on the positioning fixture 6 of the substrate 7, and the pneumatic fixture is activated to complete the centering and clamping, with the coaxiality error controlled within ±0.05mm;

[0101] The basic additive manufacturing process parameters for each region are set by the control system 3: laser wire welding laser power 1200W, shielding gas is argon, flow rate 20L / min; arc welding current 280A, voltage 28V, shielding gas is argon + 5% helium, flow rate 25L / min; laser-arc composite additive manufacturing laser power 800W, welding current 200A, voltage 24V, shielding gas flow rate 22L / min.

[0102] Based on the zoning planning results, control system 3 coordinates the control of six-axis robot 14 and six-axis robot 22 to simultaneously initiate the laser coaxial filament additive manufacturing system 1 and the electric arc additive manufacturing system 2 to perform additive manufacturing operations.

[0103] Thick-walled Class I region (12mm): Only the electric arc additive manufacturing system 2 is activated, and electric arc additive manufacturing is performed according to the preset Zig-Zag path. The welding torch 23 moves at a constant speed with the six-axis robot 22, with a wire feeding speed of 2.7m / min and a welding speed of 0.84mm / s.

[0104] Thick-walled secondary region (7mm): Simultaneously start the laser coaxial wire welding additive system 1 and the arc additive system 2 to perform laser-arc composite additive manufacturing. Maintain an 8mm distance between the laser welding gun and the arc welding gun, move along a unidirectional parallel line path, wire feed speed 2.4m / min, welding speed 0.68mm / s;

[0105] Thin-walled area (3mm): Only the laser coaxial wire bonding additive manufacturing system 1 is activated, and laser wire bonding additive manufacturing is performed according to the Zig-Zag path. The laser welding torch moves at a constant speed with the six-axis robot 14, with a wire feeding speed of 1.8m / min and a welding speed of 0.36mm / s. During the additive manufacturing process, the control system 3 monitors the motion trajectory of the two robots in real time to ensure the coordination of the operation and prevent interference.

[0106] After each layer of additive manufacturing is completed, the control system 3 activates the additive manufacturing surface vision recognition system 4 to perform a full-surface scanning inspection. The specific process is as follows:

[0107] Scanning parameter settings: Based on the slice layer thickness h, the scanning step distance s=0.5h is set, that is, s=0.1mm for thin-walled area, s=0.3mm for thick-walled secondary area, and s=0.4mm for thick-walled primary area. The scanner performs a full scan of the current additive layer according to the set step distance and transmits the initial scan data to the control system 3.

[0108] Control system 3 uses a Gaussian filtering algorithm to remove noise interference from the scanning data. Point cloud accuracy calculated: thin-walled region =0.007mm, thick-walled secondary region =0.011mm, thick-walled first-level region =0.013mm, obtaining a clean 3D point cloud;

[0109] Import the 3D point cloud into Geomagic software, align and compare it with the preset CAD model, and then... =0.15h set deviation threshold: thin-walled region =0.03mm, thick-walled secondary region =0.09mm, thick-walled first-level region =0.12mm, through Calculate the point cloud deviation and determine points with deviations greater than a threshold as defect points;

[0110] Filter and segment out independent defect point cloud clusters, according to Calculate the geometric center coordinates of the defect cluster, and define the defect size along the additive direction as length D. C The defect dimension perpendicular to the additive direction is width D. K In this implementation case, a depression defect was detected in a thick-walled Class I region, with geometric center coordinates (200mm, 150mm, 50mm). C =10mm, D K =3mm; A raised defect in the thick-walled secondary region, with geometric center coordinates (180mm, 160mm, 45mm), D C =8mm, D K =1.5mm; no obvious defects in the thin-walled area.

[0111] Control system 3 performs defect filling according to the output defect data and the laser mode. In this implementation case, D1=1mm and D2=2mm are preset, that is, D K <1mm, use mode c; 1mm <D K <2mm, use mode b, D K >2mm, use mode a, specific filling process:

[0112] Thick-walled Class I Defect Filling (D) K=3mm>D2=2mm, mode a) is adopted.

[0113] The control system 3 sends a command to the laser coaxial filament additive manufacturing system 1 to adjust the angle of the adjustable reflector 54 to +5°, switch to mode a, and synchronously adjust the laser power to 1500W (not lower than the basic laser power of 1200W). The filament feeding speed is adjusted to 1.2m / min according to the laser power to ensure that the filling layer thickness is 0.2mm.

[0114] The six-axis robot 14 moves the laser welding torch to the geometric center of the defect (200mm, 150mm, 50mm), along the defect length D. C The defect is filled by scanning at a constant speed (0.5 mm / s) along the X-axis.

[0115] Thick-walled secondary region defect filling D K =1.5mm, D1<D K <D2, using pattern b;

[0116] The control system 3 adjusts the angle of the adjustable reflector 54 to 0°, switches to mode b, adjusts the laser power to 1300W, the wire feeding speed to 1.5m / min, and the filling layer thickness to 0.15mm;

[0117] The six-axis robot 14 moves the laser welding torch to the geometric center of the defect (180mm, 160mm, 45mm), along D... C Uniform scanning and filling in the correct direction;

[0118] Filling quality verification: After the defect filling is completed, the control system 3 starts the vision recognition system to perform a local scan of the filled area. The point cloud comparison results show that the deviation after filling the thick-walled first-level area is ∆d=0.08mm<0.12mm, the deviation after filling the thick-walled second-level area is ∆d=0.05mm<0.09mm, and the surface roughness Ra=2.8μm≤3.2μm. The filling quality meets the standards and no secondary filling is required.

[0119] Repeat the above steps, completing the additive manufacturing, inspection, and defect filling operations for each layer in the order of layer slicing, until the entire component is additively manufactured.

[0120] Control system 3 controls laser coaxial filament additive manufacturing system 1 to switch to mode b, which performs overall laser additive filling on the outer surface of the component. The laser power is 1000W, the filament feeding speed is 1.0m / min, and the filling layer thickness is 0.1mm, thereby improving the surface forming quality.

[0121] Turn off all additive manufacturing systems and allow the components to cool naturally to room temperature along with the substrate (cooling time is approximately 2 hours).

[0122] The additive manufacturing surface vision recognition system 4 was activated to scan and inspect the entire component. The inspection results showed that the overall dimensional accuracy of the component was ±0.15mm, which meets the ±0.2mm requirement; the surface roughness Ra=2.5μm≤3.2μm; and the bending stiffness was 920N・m≥800N・m. All performance indicators met the design requirements, and the entire additive manufacturing process of the titanium alloy variable thickness frame component was completed.

[0123] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A variable thickness ring-shaped laser-arc complementary fused wire additive manufacturing method, characterized in that: The specific steps are as follows: S1. Based on the design drawings of the variable thickness structure and combined with the criteria of structural stiffness and process efficiency, the area is divided and the additive manufacturing path is planned. Then, the data of the divided area and the planned additive manufacturing path are entered into the control system to allocate the work area and set the safety distance. S2, three quadrature laser modes are set, and the laser coaxial filament additive manufacturing system is controlled by the control system to achieve mode switching; S3, perform surface cleaning on the substrate of the workpiece to be additively processed; fix the cleaned substrate on the positioning fixture of the substrate; set the additive process parameters through the control system; S4, based on the zoning planning results of S1, controls the synchronous start of the laser coaxial filament additive manufacturing system and the electric arc additive manufacturing system to perform additive manufacturing according to the preset process; based on the linkage control of the six-axis robot and the six-axis robot II, the coordination of the two systems is ensured and the interference of operations is avoided; S5. After each additive manufacturing operation is completed, the control system activates the additive manufacturing surface vision recognition system to perform a comprehensive scan of the current additive layer surface and transmits the initial data to the control system. The control system preprocesses the scanned data to obtain a 3D point cloud, compares it with the preset CAD model, sets a deviation threshold to filter defect points, calculates the geometric center coordinates of the defects, and defines the defect size along the additive direction as length D. C The defect dimension perpendicular to the additive direction is width D. K The final output includes the size, coordinates, and shape data of the defect. S6, based on the surface defect data output by S5, adapts the corresponding filling strategy; given the irregular shape of the defects and the differences in defect filling capabilities among the three laser modes, the applicable ranges of the three modes are divided according to the filling width of the three laser modes: D K When D1 < D1, use mode c; when D1 < D K <D2 uses pattern b, D K >D2 uses mode a; after each range of defect filling is completed, the laser coaxial filament additive system's quarter laser spacing is adjusted through the control system, and the laser mode is switched to perform the next range of defect filling; after the defect filling is completed, the additive surface is scanned again to confirm that the surface roughness meets the additive requirements; S7. Repeat steps S4-S6 until the additive manufacturing operation is completed; the control system controls the laser coaxial filament additive manufacturing system to fill the outer surface of the workpiece with laser additive manufacturing; after the workpiece has cooled down, the additive manufacturing surface vision recognition system is restarted to scan and inspect the entire workpiece to confirm that the forming quality of the workpiece meets the design requirements, thus completing the entire additive manufacturing process. The regions defined in S1 specifically include thin-walled regions (wall thickness < 5 mm, corresponding to laser additive manufacturing); thick-walled first-level regions (wall thickness ≥ 10 mm, corresponding to electric arc additive manufacturing); and thick-walled second-level regions (wall thickness 5-10 mm, corresponding to laser-electric arc composite additive manufacturing). The three quadrature laser modes in S2 are: mode a, in which the two beams of the quadrature laser are elongated along the direction perpendicular to the additive manufacturing direction; mode b, in which the two diagonals of the quadrature laser are parallel to the direction perpendicular to the additive manufacturing direction; and mode c, in which the two beams of the quadrature laser are elongated along the additive manufacturing direction.

2. The variable thickness structure annular laser-arc complementary fused wire additive manufacturing method according to claim 1, characterized in that: In step S1, based on the variable thickness structure design drawing, the design drawing is imported using Slic3r slicing software to complete the workpiece layer slicing. The slicing layer thickness is set to h, and the slicing layer thickness h is matched with the workpiece wall thickness t to ensure the additive forming quality of each layer. At the same time, the wire feeding speed is precisely set in conjunction with the slicing layer thickness h. With welding speed To ensure precise matching between wire feeding speed, welding speed, slice layer thickness, and workpiece wall thickness; for slices involving only a single area, a Zig-Zag additive path is used, which employs a reciprocating alternating scanning method; for slices involving multiple areas, a unidirectional parallel line additive path is used, and each path must pass through multiple different areas until the additive layer is completed.

3. The variable thickness structure annular laser-arc complementary fused wire additive manufacturing method according to claim 1, characterized in that: The detailed process of S5 is as follows: S51: After each additive manufacturing layer is completed, the control system activates the additive manufacturing surface vision recognition system, which uses a scanner to perform a full scan of the current additive layer surface, with a scanning step distance. With slice thickness Adaptation, satisfaction To ensure no area is missed during the scan, the initial scan data is transmitted to the control system. The control system preprocesses the scan data, first removing noise interference using a Gaussian filtering algorithm to obtain the accuracy of the filtered point cloud data. ; S52: After preprocessing, a clean 3D point cloud is obtained. This is then imported into Geomagic point cloud processing software. The 3D point cloud is aligned and compared with a preset CAD model. Arbitrary points in the point cloud are defined. The three-dimensional coordinates are The corresponding 3D coordinates of the points on the CAD model are Then the deviation at that point Set deviation threshold Its relationship with slice thickness The quantitative relationship is =0.15h, when > When this point is identified, it is determined to be a defect point; S53: Independent defect point cloud clusters are filtered and segmented using software; a single defect point cloud cluster is defined as containing… There are 3 defect points, and the geometric center coordinates of the defect cluster are given as follows: ; S54: Construct a central axis passing through the geometric center coordinates and parallel to the additive direction. Define the defect size along the central axis as length D. C The defect dimension perpendicular to the central axis is width D. K Output the size of the defect (D) C D K Geometric center coordinates and morphological data.

4. The variable thickness structure annular laser-arc complementary fused wire additive manufacturing method according to claim 1, characterized in that: The detailed process of S6 is as follows: S61: The control system receives the size, coordinates, and shape data of the defect output from step S5, and extracts the defect width D. K Parameters; then, based on the differences in additive width corresponding to the three four-part laser modes, the additive width and defect width D of the laser mode are established. K The adaptation relationship is set by defining two thresholds, D1 and D2, to determine the defect width D. K It is divided into three different adaptation ranges; S62: Based on the laser mode obtained from the above matching, the control system sends a precise control command to the laser coaxial filament additive manufacturing system to adjust the angle of the adjustable mirror in the laser mirror group, thereby changing the spacing of the ring laser beam and achieving precise switching of the laser mode; at the same time, the laser power and wire feeding speed are adjusted synchronously, wherein the laser power is filled to no less than the laser power of laser filament additive manufacturing in step S4, and the wire feeding speed is reduced synchronously with the laser power to ensure that the filling layer thickness is controlled within the range of 0.1mm-0.3mm; S63: Laser-coaxial fused wire additive manufacturing system based on defect geometric center coordinates Under the coordinated control of a six-axis robot, it moves to the location of the defect and performs defect filling operations according to the matched laser pattern, with the filling path along the defect length D. C Uniform scanning in the direction; S64: If a single defect point cloud cluster has multiple segments with different D K For defect areas of a certain width, then according to D K The thresholds are matched with the corresponding laser modes in descending order; after each defect filling of a width range is completed, the mode switching and parameter adjustment operation in step S62 is repeated, and then the filling operation of the next width range is performed until the filling work of the defect point cloud cluster is completed. S65: After a single defect or all defects are filled, the control system restarts the additive manufacturing surface vision recognition system to perform a local scan of the filled area. The point cloud data obtained from the scan is compared with the preset CAD model to verify whether the surface deviation of the filled area is less than the preset threshold and to confirm that the surface roughness meets the additive design requirements. If the filling quality does not meet the standards, the steps S61-S64 are repeated for a second filling until the design requirements are met.

5. The variable thickness structure annular laser-arc complementary fused wire additive manufacturing method according to claim 4, characterized in that: The adjustable mirror in S62 has an angle adjustment range of -15° to 15° and an adjustment accuracy of 0.1°. The angle change of the mirror directly determines the spacing of the ring laser beams: when the mirror angle increases, the angle between the emission directions of the sub-laser beams increases, and the spacing of the ring laser beams increases accordingly; when the mirror angle decreases, the spacing of the ring laser beams decreases. Different additive filling strategies can be adapted through the above angle adjustment.

6. A variable thickness ring-shaped laser-arc complementary fused wire additive manufacturing device, operating the method described in claim 1, characterized in that: The device includes: a laser coaxial fused wire additive manufacturing system, an electric arc additive manufacturing system, a control system, and a visual recognition system for additive manufacturing surfaces; The laser coaxial wire melting additive manufacturing system includes a wire feeder, a laser, an optical fiber, a six-axis robot, and a laser mirror assembly. The laser is controlled by the six-axis robot, and its laser power is adjusted and its laser beam is controlled by the control system. The laser beam is transmitted to the laser mirror assembly through the optical fiber, and four ring laser beams are formed under the action of the laser mirror assembly. The ring laser beams are used to melt the welding wire to complete the additive manufacturing process. The electric arc additive manufacturing system includes an electric arc power source, a wire feeder, a six-axis robot, and a welding torch. It completes the additive manufacturing process by melting the welding wire with an electric arc. The control system precisely regulates each system to perform additive manufacturing operations based on the zoning processing results of the variable thickness structure. At the same time, based on the surface defect data fed back by the additive manufacturing surface vision recognition system, the system adjusts the spacing of the ring laser beams of the laser coaxial filament additive manufacturing system and uses three laser modes to perform additive filling operations. The additive manufacturing surface vision recognition system includes a laser additive scanner and an arc additive scanner, which are fixed on both sides of the laser welding gun and the arc welding gun, respectively. They scan the additive surface synchronously with the additive process and transmit the obtained morphology data to the control system. After processing by the control system, the surface accuracy data after additive manufacturing is obtained. The control system implements the corresponding filling strategy based on the surface accuracy data.

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