An adaptive wire-powder synchronous laser welding method and device for uneven gap welds

Abstract

The present invention belongs to the field of welding manufacturing technology, and discloses an adaptive wire-powder synchronous laser welding method and device for uneven gap welds. The device mainly comprises a laser welding system, a robot work platform system, a wire-powder synchronous feeding mechanism, a protective gas system and a real-time control system based on a laser vision sensor device. The method adopts a laser vision sensor device to observe and detect the geometric characteristics of the variable gap weld in real time during the laser welding process, and compensates the operation through an efficient algorithm to feed back the operation results. According to the results, the laser power, laser welding mode, wire / powder filling amount and other process parameters are adaptively adjusted to finally achieve the shape control of the uneven gap weld adaptive laser welding. The adaptive wire-powder mixed laser welding method adopted by the present invention has high measurement accuracy, high control efficiency, fast response speed, strong adjustment ability, and can realize automatic welding online real-time feedback control, solving the problem of poor forming during the welding process of uneven welds.

Description

Technical Field

[0001] The invention belongs to the technical field of welding manufacturing, and discloses an adaptive wire-powder synchronous laser welding method and device for uneven gap welds. Background Art

[0002] Laser beam welding unit technology for complex, thin-walled components in the aviation industry currently faces a major challenge: the pre-welding manufacturing method uses sheet metal forming and mechanical cutting, resulting in extremely poor straightness and unevenness along the edges to be welded. This results in the gap uniformity of the welded parts not meeting the requirements after assembly. The lack of machining precision for large, complex structures limits the application of laser welding technology. Uneven weld gaps and excessively large gaps in certain locations can lead to frequent welding defects such as undercutting, lack of fusion, and poor back-forming, which affect welding quality. To address the welding defects caused by uneven gaps, existing solutions often involve manually measuring the gap distribution and marking them in sections. Different welding techniques and specifications are used for different gaps, resulting in reduced production efficiency, a sharp increase in the number of weld joints, and a subsequent increase in the defect rate. Therefore, there is an urgent need to develop a highly adaptive laser welding method for uneven gaps that can achieve high-quality, automated welding with controllable fill volumes under conditions of constantly changing joint gap sizes. Summary of the Invention

[0003] The purpose of the present invention is to provide an adaptive wire-powder synchronous laser welding method and device for uneven gap welds. Through the method of "weld gap state pre-scan → efficient algorithm compensation calculation → adaptive control of laser power, laser welding mode, and wire / powder filling amount", adaptive and precise control of uneven gap welds is achieved, solving the frequent welding defects caused by uneven gap structures in the aerospace field.

[0004] To achieve this object, the present invention adopts the following technical solutions:

[0005] An adaptive wire-powder synchronous laser welding method for uneven gap welds, comprising the following steps:

[0006] Step 1: Turn on the shielding gas system to ensure that the workpiece to be welded and the filler material in the shielding chamber are continuously in a high-purity inert atmosphere during the welding process;

[0007] Step 2: Turn on the robot work platform system and real-time control system in sequence to control the movement of the six-axis robot so that the laser vision sensor fixed to the side of the laser head in the welding direction scans the gap size. The laser vision sensor emits a line laser perpendicular to the welding direction, identifies and collects the surface contour of the weld line by line along the welding direction, and analyzes the spatial geometric characteristics of the weld gap.

[0008] Step 3: The laser vision sensor imports the weld gap spatial geometric feature image data into the computer 3D reconstruction software, and measures and calculates the gap position, size and other geometric parameters. A first-order derivative is taken for each contour, and the two extreme points of the first-order derivative are defined as the gap feature points, thereby obtaining the gap size at the scanned contour position. Combining the position information of each contour with the corresponding gap size, a gap curve along the welding direction is obtained. The gap curve is subjected to a combination of limiting filtering, Gaussian filtering, and median filtering to remove noise and smooth the curve, thereby obtaining gap data that is easy to call.

[0009] Step 4: The filtered gap curve is transferred to the algorithm processor for efficient algorithm compensation calculation, and feedback control is used to adjust process parameters such as wire feeding speed and powder feeding speed. Specifically: when the weld gap size is detected to be less than the threshold value of 0.3mm, the wire-powder synchronous feeding mechanism is not started, and laser self-melting welding is performed at this time; when the gap size is detected to be between the threshold value of 0.3mm and 0.6mm, the wire feeding mechanism is started, and laser wire filling welding is performed at this time; when the weld gap size is detected to be less than the threshold value of 0.6mm, the powder feeding mechanism is started, and wire-powder synchronous laser welding is performed at this time;

[0010] Step 5: The algorithm processor adjusts the wire feeding speed, powder feeding speed and laser power in real time according to the gap threshold. As the gap size GAP to be welded increases, the wire feeding speed V is adjusted. w , powder feeding speed V a , laser power P increases by a factor of K, specifically: wire feeding speed and gap K a The coefficient increases linearly, the wire feeding speed V w =0.6m / min+(GAP-0.3mm)×K a ; Powder feeding speed is proportional to the gap value K b The coefficient increases linearly, and the powder feeding speed V a =0.7r / s+(GAP-0.6mm)×K b ; Laser power and wire feeding speed V w Cheng K c The coefficient changes linearly, laser power P = 3000W + (Vw-0.3m / min) × K c , and finally realize adaptive silk-powder synchronous laser welding to solve the problem of poor weld formation with uneven gaps.

[0011] Optionally, the gap size tolerance threshold of laser autogenous welding is 0.3mm, and the tolerance threshold of laser wire welding is 0.6mm. The threshold range is determined based on the existing laser processing technology level and equipment conditions. If the equipment is replaced, preliminary experiments are required to revise the threshold range.

[0012] Optionally, when laser welding different metal materials, the wire feeding speed V w, powder feeding speed V a and the control coefficient K of the laser power P a , K b , K c If there are changes, process tests are carried out based on the unique welding characteristics of the material, and the growth coefficient is revised by fitting.

[0013] Optionally, the uneven gap weld refers to a significant change in the gap size GAP of the structure to be welded, specifically including: a. irregular gap: uneven gap size before welding due to inconsistent material processing and assembly dimensions; b. variable gap: during the welding manufacturing process, large-sized thin-walled structures have deformation during welding, resulting in uneven weld gap; c. bevel gap: large-sized curved surface structures have multi-position welding, and the transition position of the curved surface often presents a beveled edge on one side due to the difficulty of manufacturing, and the gap shape of the transition weld position is uneven.

[0014] An adaptive wire-powder synchronous laser welding device for uneven gap welds, mainly including a laser welding system, a robot work platform system, a wire-powder synchronous feeding mechanism, a shielding gas system and a real-time control system;

[0015] The laser welding system uses a laser generator to generate a high-energy beam light source, which is transmitted to the laser galvanometer chamber through an optical fiber and acts on the surface of the workpiece to be welded in an inert gas protection chamber;

[0016] The robot work platform system is used to control the welding work path, including a workbench, a six-axis robot, and a lifting fixed fixture;

[0017] The wire-powder synchronous feeding mechanism is controlled by a real-time control system and includes a powder feeder, a powder storage tank, a wire feeder, a wire guide nozzle, and a laser head connected to a powder feeding pipe, which synchronously inputs the filling wire and powder materials to the welding position;

[0018] The shielding gas system consists of a shielding gas cylinder, a gas supply pipe, and a shielding chamber to be welded. By controlling the shielding gas valve, the gas supply pipe is connected to the air inlet valve near the bottom center of the side of the shielding chamber to provide inert gas inside the shielding chamber. A light-reducing observation window and high-temperature-resistant rubber gloves are installed in front of the shielding chamber for real-time observation of the welding process and experimental operations.

[0019] The real-time control system uses a laser vision sensor to identify, locate, and reconstruct the weld's shape in three dimensions, extract key dimensions of the weld gap state, transmit the real-time monitoring results to a computer and algorithm processor, and implement synchronous adaptive parameter control of wire and powder for uneven gap welds.

[0020] Optionally, the wire-powder synchronous feeding mechanism realizes the controllable input of wire-powder materials to be welded. According to the planned process parameters and the parameter adjustment function of the real-time control system, the input wire and powder materials are melted and filled in the uneven gap weld through the action of the laser heat source, thereby finally achieving effective connection of the uneven gap.

[0021] Optionally, the wire guide nozzle in the wire-powder synchronous feeding mechanism is fixed beside the laser head, and the relative position of the wire guide nozzle and the laser head is adjusted by fasteners to achieve adjustable height, angle, and filament spacing; one end of the powder feeding duct is connected to the powder storage tank, and the other end is fixed above the laser head, and the powder feeder evenly inputs powder into the gap to be welded, forming an integrated laser welding filler equipment with side-axis wire feeding and coaxial powder feeding.

[0022] The beneficial effects of the present invention are as follows:

[0023] The present invention provides an adaptive wire-powder synchronous laser welding method and device for uneven gap welds. The method uses a laser vision sensor to pre-scan the gap size, and uses image acquisition software to perform three-dimensional reconstruction of the gap space geometric features on the scanning path. Then, geometric feature analysis and efficient algorithm compensation operations are performed on the three-dimensionally reconstructed gap space geometric features. According to the calculation results, adaptive feedback control is used to adjust process parameters such as laser power, laser welding mode (such as laser autogenous welding, laser wire filling welding or wire-powder mixed synchronous laser welding), and wire / powder filling amount, ultimately realizing automatic welding online real-time feedback control, thereby solving the problem of poor weld formation caused by the continuous change of the weld gap during automatic welding. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the structure of the laser head with integrated wire feeding and powder feeding mechanism and the structure of the uneven gap weld;

[0025] Figure 2 It is a structural schematic diagram of the silk-powder synchronous laser welding system provided by the present invention;

[0026] Figure 3 A schematic diagram of the process flow of data processing during the weld gap pre-scanning process provided by the present invention;

[0027] Figure: 1. Shielding gas; 2. Gas pipe; 3. Powder feeder; 4. Powder storage tank; 5. Laser generator; 6. Optical fiber; 7. Wire feeder; 8. Workbench; 9. Inlet valve; 10. High-temperature rubber gloves; 11. Light-reducing observation window; 12. Inert gas protection chamber; 13. Computer; 14. Six-axis robot; 15. Wire guide nozzle; 16. Laser cladding head; 17. Laser galvanometer chamber; 18. Algorithm processor; 19. Liftable fixture; 20. Laser vision sensor.

[0028] 161. Powder delivery conduit 1; 162. Powder delivery conduit 2; 163. Powder delivery conduit 3; 164. Powder delivery conduit 4; 165. Powder gathering channel; 166. Multi-axis adjustable fastening device. Specific implementation methods

[0029] The present invention is described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are intended only to illustrate the present invention and are not intended to limit the present invention. It should also be noted that, for ease of description, the accompanying drawings only illustrate portions relevant to the present invention, not all structures.

[0030] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings in the embodiments of the present invention.

[0031] Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0032] In the description of the present invention, unless otherwise expressly specified or limited, the terms "connected," "connected," and "fixed" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0033] In the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Furthermore, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly below or obliquely below the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0034] In the description of this embodiment, the terms "upper," "lower," "right," and other orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely for ease of description and simplified operation. They do not indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first" and "second" are used solely for descriptive purposes and have no special meanings.

[0035] This invention discloses an adaptive wire-powder synchronous laser welding method and device for uneven gap welds. Through a method that involves "pre-scanning the weld gap state → performing efficient algorithm compensation calculations → adaptively controlling laser power, laser welding mode, and wire / powder loading," this method achieves precise and adaptive control of uneven gap welds. The device primarily comprises a laser welding system, a robotic work platform system, a wire-powder synchronous feeding mechanism, a shielding gas system, and an online control and monitoring system.

[0036] The present invention is further illustrated below by a specific embodiment.

[0037] This example uses the adaptive wire-powder synchronous laser welding device to achieve butt welding of 4mm TC4 titanium alloy sheets with uneven gaps. The implementation process is as follows:

[0038] Step 1: Before welding, fix the TC4 test plate fixture in the protective chamber (12), close the cabin door, open the protective gas cylinder (1), and introduce inert gas into the gas protective chamber (12) through the gas pipe (2) and the air inlet valve (9) to ensure that the workpiece to be welded and the filler welding material in the protective chamber are continuously in a high-purity inert atmosphere during the welding process;

[0039] Step 2: Turn on the robot work platform system and the real-time control system in sequence, control the six-axis robot (14) to move, and make the laser vision sensor (20) fixed on the side of the laser head in the welding direction scan the gap size. The laser vision sensor (20) emits a line laser perpendicular to the welding direction, identifies and collects the weld surface contour morphology line by line along the welding direction, and analyzes the spatial geometric characteristics of the weld gap.

[0040] Step 3: The laser vision sensor sends the weld gap spatial geometric feature image data to the computer (13) 3D reconstruction software in real time, with a data sending interval of 50ms. Through median filtering and average filtering, the pixel fluctuation caused by reflection can be effectively controlled, and the geometric feature quantity of the weld gap is extracted. The extracted data contains 4 key parameters: ΔX, ΔY, ΔZ, GAP, and the functional relationship curve between the misalignment and the weld length, and the gap and the weld length is established. The curve is subjected to a combination of limiting filtering, Gaussian filtering, and median filtering to remove noise and smooth the curve, thereby obtaining gap data that is easy to call.

[0041] Step 4: The filtered gap curve is transferred to the algorithm processor (18) for efficient algorithm compensation calculation and feedback control to adjust process parameters such as wire feeding speed and powder feeding speed. Specifically: when the weld gap size is detected to be less than the threshold value of 0.3mm, the wire-powder synchronous feeding mechanism is not started, and laser self-melting welding is performed at this time; when the gap size is detected to be between the threshold value of 0.3mm and 0.6mm, the wire feeding mechanism is started, and laser wire filling welding is performed at this time; when the weld gap size is detected to be less than the threshold value of 0.6mm, the powder feeding mechanism is started, and wire-powder synchronous laser welding is performed at this time;

[0042] Step 5: The algorithm processor adjusts the wire feeding speed, powder feeding speed and laser power in real time according to the gap threshold. The welding gap of TC4 titanium alloy sheet fluctuates in the range of 0.2mm to 0.9mm. As the gap size GAP to be welded increases, the wire feeding speed V is adjusted. w , powder feeding speed V a , laser power P increases by a factor of K, specifically: wire feeding speed and gap K a =1.34 coefficient linear growth, wire feeding speed V w =0.6m / min+(GAP-0.3mm)×1.34; powder feeding speed is proportional to the gap value K b =2.19 coefficient linear growth, powder feeding speed V a =0.7r / s+(GAP-0.6mm)×2.19; Laser power and wire feeding speed V w Cheng K c =1500 coefficient changes linearly, laser power P = 3000W + (Vw-0.3m / min) × 1500, and finally adaptive wire-powder synchronous laser welding is realized to solve the problem of poor weld formation with uneven gap.

[0043] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

[0044] The present invention is not limited in any way to the exemplary embodiments presented in the specification and drawings. Portions of the illustrated and described embodiments are expressly understood to be incorporated into this specification and to fall within the scope of the present invention. Moreover, many variations are possible within the scope of the invention as outlined in the claims. Furthermore, any reference signs in the claims should not be construed as limiting the scope of the invention.

Claims

1. An adaptive wire-powder synchronous laser welding method for uneven gap welds, comprising the following steps: Step 1: Turn on the shielding gas system to ensure that the workpiece to be welded and the filler material in the shielding chamber are continuously in a high-purity inert atmosphere during the welding process; Step 2: Turn on the robot work platform system and the real-time control system in sequence, control the six-axis robot (14) to move, and make the laser vision sensor (20) fixed on the side of the laser head in the welding direction scan the gap size. The laser vision sensor (20) emits a line laser perpendicular to the welding direction, identifies and collects the weld surface contour morphology line by line along the welding direction, and analyzes the spatial geometric characteristics of the weld gap. Step 3: The laser vision sensor (20) imports the weld gap spatial geometric feature image data into the computer (13) three-dimensional reconstruction software, and measures and calculates the geometric parameters such as the gap position and size, performs a first-order derivative for each contour, and defines the two extreme points of the first-order derivative as the gap feature points, thereby obtaining the gap size of the scanned contour position, combining the position information of each contour with the corresponding gap size, and obtaining the gap curve along the welding direction. The gap curve is subjected to a combination filtering process of limiting filtering, Gaussian filtering, and median filtering to remove noise and smooth the curve, thereby obtaining gap data that is easy to call; Step 4: The filtered gap curve is transmitted to the algorithm processor (18), and an efficient algorithm compensation operation is performed, and the wire feeding speed and the powder feeding speed are adjusted by feedback control. Specifically, when the weld gap size is detected to be less than the threshold value of 0.3 mm, the wire-powder synchronous feeding mechanism is not started, and laser self-melting welding is performed at this time; when the gap size is detected to be between the threshold value of 0.3 mm and 0.6 mm, the wire feeding mechanism is started, and laser wire filling welding is performed at this time; when the weld gap size is detected to be greater than the threshold value of 0.6 mm, the powder feeding mechanism is started, and wire-powder synchronous laser welding is performed at this time; Step 5: The algorithm processor adjusts the wire feeding speed, powder feeding speed and laser power in real time according to the gap threshold. As the gap size GAP to be welded increases, the wire feeding speed V is adjusted. w , powder feeding speed V a , laser power P increases by a factor of K, specifically: wire feeding speed and gap K a The coefficient increases linearly, the wire feeding speed V w =0.6m / min+(GAP-0.3mm)×K a ; Powder feeding speed is proportional to the gap value K b The coefficient increases linearly, and the powder feeding speed V a =0.7r / s+(GAP-0.6mm)×K b ; Laser power and wire feeding speed V w Cheng K c The coefficient changes linearly, laser power P = 3000W + (Vw-0.3m / min) × K c , and finally realize adaptive silk-powder synchronous laser welding to solve the problem of poor weld formation with uneven gaps.

2. The adaptive wire-powder synchronous laser welding method for uneven gap welds according to claim 1, characterized in that: The gap size tolerance threshold for laser autogenous welding is 0.3mm, and the tolerance threshold for laser wire welding is 0.6mm. The threshold range is determined based on the existing laser processing technology level and equipment conditions. If the equipment is replaced, preliminary experiments are required to revise the threshold range.

3. The adaptive wire-powder synchronous laser welding method for uneven gap welds according to claim 2, characterized in that: When laser welding different metal materials, the wire feeding speed V w , powder feeding speed V a and the control coefficient K of the laser power P a , K b , K c If there are changes, process tests are carried out based on the unique welding characteristics of the material, and the growth coefficient is revised by fitting.

4. The adaptive wire-powder synchronous laser welding method for uneven gap welds according to claim 3, characterized in that: The uneven gap weld refers to a weld in which the gap size GAP of the structure to be welded has obvious changes, specifically including: a. irregular gap: uneven gap size before welding due to inconsistent material processing and assembly dimensions; b. variable gap: during the welding manufacturing process, large-sized thin-walled structures have deformation during welding, resulting in uneven weld gap; c. bevel gap: large-sized curved structures have multi-position welding, and the transition position of the curved surface often presents an oblique edge on one side due to the difficulty of manufacturing, and the gap shape of the transition weld position is uneven.

5. The device used in the adaptive wire-powder synchronous laser welding method for uneven gap welds according to claim 1 mainly comprises a laser welding system, a robotic work platform system, a wire-powder synchronous feeding mechanism, a shielding gas system, and a real-time control system; The laser welding system generates a high-energy beam light source from a laser generator (5), transmits the high-energy beam light source to a laser galvanometer chamber (17) through an optical fiber (6), and acts on the surface of a workpiece to be welded in an inert gas protection chamber (12); The robot work platform system is used to control the welding work path, and includes a workbench (8), a six-axis robot (14), and a lifting fixed fixture (19); The wire powder synchronous feeding mechanism is controlled by a real-time control system and includes a powder feeder (3), a powder storage tank (4), a wire feeder (7), a wire guide nozzle (15) and a laser head (16) connected to a powder feeding pipe, and synchronously inputs the filling wire and powder material to the position to be welded; The protective gas system is composed of a protective gas cylinder (1), a gas delivery pipe (2) and a protective cabin to be welded (12). By controlling the switch of the protective gas valve, the gas delivery pipe (2) is connected to an air inlet valve (9) near the middle position of the bottom end of one side of the protective cabin (12), so as to provide inert gas in the protective cabin (12). A light-reducing observation window (11) and high-temperature resistant rubber gloves (10) are installed in front of the protective cabin (12) for real-time observation of the welding process and experimental operation. The real-time control system comprises a laser vision sensor (20), a computer (13) and an algorithm processor (18). The laser vision sensor (20) is used to identify, locate and reconstruct the three-dimensional shape of the weld, extract the key dimensions of the weld gap state, transmit the real-time monitoring results to the computer (13) and the algorithm processor (18), and implement wire-powder synchronous adaptive parameter control for uneven gap welds.

6. The adaptive wire-powder synchronous laser welding device for uneven gap welds according to claim 5, characterized in that: The wire-powder synchronous feeding mechanism realizes the controllable input of the wire-powder materials to be welded. According to the planned process parameters and the parameter adjustment function of the real-time control system, the input wire and powder materials are melted and filled into the uneven gap weld by the action of the laser heat source, thereby finally achieving effective connection of the uneven gap.

7. The adaptive wire-powder synchronous laser welding device for uneven gap welds according to claim 6, characterized in that: In the wire-powder synchronous feeding mechanism, the wire guide nozzle (15) is fixed to the side of the laser head (16), and the relative position of the wire guide nozzle and the laser head is adjusted by fasteners to achieve adjustable height, angle, and wire spacing; one end of the powder feeding conduit is connected to the powder storage tank (4), and the other end is fixed above the laser head (16), and the powder is evenly fed into the gap to be welded by the powder feeder (3), forming an integrated laser welding filler equipment with side-axis wire feeding and coaxial powder feeding.

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