Narrow gap gas shielded welding method based on visual tracking

Abstract

The invention discloses a narrow-gap gas shielded welding method based on visual tracking, which comprises the following steps of: sending a scanned central position of a welding seam to a narrow-gap welding robot, and moving the narrow-gap welding robot to a formulated position of the welding seam with a large depth-to-width ratio to carry out automatic welding. And the visual tracking feedback module is used for extracting the welding seam with the large depth-to-width ratio, data are transmitted to the robot, the welding seam with the large depth-to-width ratio is automatically positioned, and a welding track is generated. And the narrow gap welding robot is used for welding the ball valve welding seam according to the welding track, the preset welding posture and the welding process specification. By means of the method, welding of the large-depth-to-width-ratio welding seam with the depth range being 50-150 mm can be achieved. The welding universality and the automation degree are greatly improved, the quality of welding seams can be effectively improved, the production efficiency is improved, and the production cost is saved.

Description

Technical Field

[0001] The invention relates to the field of production and manufacturing of water turbine units, and in particular to a narrow gap gas shielded welding method based on visual tracking. Background Art

[0002] The ball valve is one of the key components of the turbine unit. It controls the operation and stop of the turbine unit by opening and closing the valve. Its quality is an important factor in ensuring the safe operation of the hydropower station. When producing ball valves in the traditional production method, manual gas shielded welding is used. The welding volume is large and the welds need to be welded in sections. There are many joints, which are prone to internal defects that affect product quality. Rework will extend production time and increase production costs, and it is easy to cause quality loss or affect the image.

[0003] Robotic narrow gap welding often replaces manual welding to obtain stable and reliable quality. It is generally based on teaching programming or offline programming methods. However, for workpieces with complex curvature changes such as ball valves, teaching programming or offline programming is required between layers and between passes. The programming workload is large, the degree of automation is not obvious, and the production efficiency is low. With the development of computer technology and sensor technology, adding eyes and thinking brains to robot welding is an inevitable development trend of intelligent manufacturing technology. Summary of the invention

[0004] In order to overcome the problem of large workload and low production efficiency of robot welding based on teaching programming and offline programming for large depth-width ratio welds in the background technology, the present invention provides a narrow gap gas shielded welding method based on visual tracking, which specifically includes the following steps:

[0005] S1. After the ball valve is assembled, fix it so that the weld with large depth-to-width ratio is in the flat welding position. A visual tracking feedback module is installed on the narrow gap welding robot to weld the ball valve.

[0006] S2. Perform hand-eye calibration on the narrow gap welding robot and the visual tracking feedback module to determine the relative position relationship between the narrow gap welding robot and the visual tracking feedback module to ensure that the visual tracking feedback module is in the optimal working range;

[0007] S3, weld tracking, identification and positioning: The visual tracking feedback module uses laser to scan the weld with large aspect ratio, collects the weld edge information and calculates the weld center position during the scanning process, and sends it to the narrow gap welding robot;

[0008] S4. Adjust the position of the narrow gap welding robot: set the side of the narrow gap welding robot equipped with the visual tracking feedback module as the welding forward direction, adjust the lateral offset and the longitudinal offset on the terminal of the visual tracking feedback module according to the relative position relationship between the narrow gap welding robot and the visual tracking feedback module, and adjust the position of the narrow gap welding robot;

[0009] S5. Setting the welding posture of the narrow gap welding robot: according to the curvature change of the large aspect ratio weld, a series of narrow gap welding robot welding postures are set on the weld so that the angle between the welding wire and the groove is kept consistent during the welding process;

[0010] S6. Automatic welding with visual tracking feedback function. Using pulse MIG welding method, the narrow gap welding robot completes automatic welding under the guidance of the visual tracking feedback module and automatically adjusts according to the set welding posture during the welding process;

[0011] S7. After each weld is completed, adjust the lateral offset and longitudinal offset on the visual tracking feedback module terminal and adjust the position of the narrow gap welding robot so that the welding wire can always point to the desired welding position;

[0012] S8. After welding to a certain depth, adjust the relative position of the visual tracking feedback module and the narrow gap welding robot to place the visual tracking feedback module in the optimal working range.

[0013] In the above-mentioned robot narrow gap gas shielded welding method for large aspect ratio welds based on visual tracking feedback, in S1, the depth range of the large aspect ratio weld is 50 to 150 mm.

[0014] In the above-mentioned robot narrow gap gas shielded welding method for a large aspect ratio weld based on visual tracking feedback, in S2, the optimal working range of the visual tracking feedback module from the edge of the large aspect ratio weld is 100 to 150 mm.

[0015] In the above-mentioned large aspect ratio weld robot narrow gap gas shielded welding method based on visual tracking feedback, in S6, the welding wire is ER80S-G with a diameter of φ1.2mm, the shielding gas is 78% Ar+22% CO2, the gas flow rate is 15L / min~20L / min, the welding process parameters are current 240A~280A, voltage 22V~28V, and welding speed 20cm / min~35cm / min.

[0016] In the above-mentioned robot narrow gap gas shielded welding method for large aspect ratio welds based on visual tracking feedback, in S7, by adjusting the lateral offset and the longitudinal offset on the visual tracking feedback module terminal, the welding of a 50 mm thick narrow gap weld can be completed at one time without adjusting the position of the visual tracking feedback module.

[0017] Due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0018] 1. The present invention is an innovation in the welding process of large depth-width ratio welds of water turbine units. The process used in the present invention has stable and reliable welding quality, is not affected by human factors, greatly improves the welding quality of large depth-width ratio welds, and greatly reduces the production cycle and production cost.

[0019] 2. The visual tracking feedback technology used in the present invention saves manual teaching programming and off-line programming of welds and improves efficiency.

[0020] 3. The visual tracking feedback technology used in the present invention uses laser scanning to replace the human eye to identify the welding path, and plans the trajectory of the welding path according to the setting of the welding posture, so as to achieve the purpose of autonomous teaching of the robot, thereby greatly improving the intelligent automation level of the welding robot.

[0021] 4. The present invention is an innovation of the traditional welding method, and can be extended to the welding of seat rings, top covers, bottom rings and other products in turbine units, and to the production of equipment manufacturing peers, thus generating significant social benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the ball valve narrow gap welding robot automated welding.

[0023] Figure 2 Set up a schematic diagram for the weld pose.

[0024] Figure 3 This is a flow chart of the narrow gap gas shielded welding method based on visual tracking.

[0025] Figure markings: 1-ball valve, 2-large aspect ratio weld, 3-narrow gap welding robot, 4-visual tracking feedback module, 5-a series of welding gun postures. DETAILED DESCRIPTION

[0026] In order to make the technical solutions and beneficial effects of the present invention more clear, the technical solutions in the embodiments of the present invention are clearly and completely described below in conjunction with the accompanying drawings.

[0027] Specific implementation method 1: refer to Figure 1 to Figure 2 This embodiment describes a narrow gap gas shielded welding method based on visual tracking, which is implemented by the following steps:

[0028] S1. After the ball valve 1 is assembled and fixed, the large aspect ratio weld 2 is in a flat welding position. A visual tracking feedback module 4 is installed on the narrow gap welding robot 3 to calculate the weld center data point and transmit it to the welding robot 3 through TCP / IP communication. After receiving the command, the welding robot 3 analyzes and executes the corresponding movement to weld the ball valve 1.

[0029] S2, perform hand-eye calibration on the narrow gap welding robot 3 and the visual tracking feedback module 4, determine the relative position relationship between the narrow gap welding robot 3 and the visual tracking feedback module 4, and ensure that the visual tracking feedback module is in the optimal working range;

[0030] S3, weld tracking, identification and positioning: the visual tracking feedback module 4 uses a laser to scan the large aspect ratio weld 2, collects weld edge information during the scanning process, calculates the weld center position, and sends it to the narrow gap welding robot 3;

[0031] S4, adjusting the position of the narrow gap welding robot: setting the side of the narrow gap welding robot 3 equipped with the visual tracking feedback module 4 as the welding forward direction, and adjusting the lateral offset and the longitudinal offset on the terminal of the visual tracking feedback module 4 according to the relative position relationship between the narrow gap welding robot 3 and the visual tracking feedback module 4, so that the welding wire can point to the target weld bead position;

[0032] S5, setting the welding posture of the narrow gap welding robot: according to the curvature change of the large aspect ratio weld 2, a series of narrow gap welding robot welding postures 5 are set on the weld so that the angle between the welding wire and the groove is kept consistent during the welding process;

[0033] S6. Automatic welding using the visual tracking feedback function, using the pulse MIG welding method, the narrow gap welding robot 3 completes the automatic welding under the guidance of the visual tracking feedback module 4, and automatically adjusts according to the set welding posture during the welding process;

[0034] S7, after each weld is completed, adjust the lateral offset and the longitudinal offset on the terminal of the visual tracking feedback module 4 so that the welding wire can always point to the target weld position;

[0035] S8. After welding to a certain depth, adjust the relative position of the visual tracking feedback module 4 and the narrow gap welding robot 3 so that the visual tracking feedback module is in the optimal working range.

[0036] Specific implementation method 2: refer to Figure 1 to Figure 2 This embodiment is described. This embodiment further limits S1 described in the first embodiment. In this embodiment, in S1, the depth range of the large aspect ratio weld is 50 to 150 mm.

[0037] Specific implementation method three: refer to Figure 1 to Figure 2 This embodiment is described as further limiting S2 described in the first embodiment. In this embodiment, the optimal working range of the visual tracking feedback module in S2 is 100 to 150 mm from the edge of the weld with a large aspect ratio. Other components and connection methods are the same as those in the first embodiment.

[0038] This is a preferred implementation scheme of the present invention, which places the visual tracking feedback module in the optimal working range. Under the premise that the visual tracking system works stably, the visual tracking is not lost or offset during the welding process, thereby ensuring the quality of the weld.

[0039] Specific implementation method 4: refer to Figure 1 to Figure 2 This embodiment is described. This embodiment further limits the S6 described in the specific embodiment 1. In this embodiment, the welding wire in the S6 is ER80S-G with a diameter of φ1.2 mm, the shielding gas is 78% Ar+22% CO2, the gas flow rate is 15L / min-20L / min, the welding process parameters are current 240A-280A, voltage 22V-28V, and welding speed 20cm / min-35cm / min. Other components and connection methods are the same as those in the specific embodiment 1.

[0040] This is a preferred implementation scheme of the present invention. Robot welding can perform operations strictly in accordance with predetermined process specifications, achieve ultra-low spatter effects, and greatly improve welding quality.

[0041] Specific implementation method five: refer to Figure 1 to Figure 2 This embodiment is described. This embodiment further limits the S7 described in the specific embodiment 1. In this embodiment, by adjusting the lateral offset and the longitudinal offset on the visual tracking feedback module terminal in S7, the welding of a 50 mm thick narrow gap weld can be completed at one time without adjusting the position of the visual tracking feedback module.

[0042] This is a preferred embodiment of the present invention, which can complete the welding of 50mm thick narrow gap welds with only one calibration, avoiding repeated interlayer calibration or offline programming during welding, shortening the time required for manual teaching, and greatly improving production efficiency. Finally, the scope of protection of the present invention is not limited to the above-mentioned embodiments. Obviously, those skilled in the art can make various changes and deformations to the present invention without departing from the scope and spirit of the present invention. If these changes and deformations fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these changes and deformations.

Claims

1. A narrow gap gas shielded welding method based on visual tracking, the characteristics of which include Follow these steps: S1. After assembling, the ball valve (1) is fixed so that the large depth-to-width ratio weld (2) is in a flat welding position, and a visual tracking feedback module (4) is installed on a narrow gap welding robot (3) to weld the ball valve (1); S2, performing hand-eye calibration on the narrow gap welding robot (3) and the visual tracking feedback module (4), determining the relative position relationship between the narrow gap welding robot (3) and the visual tracking feedback module (4), and ensuring that the visual tracking feedback module (4) is in an optimal working range; S3, weld tracking, identification and positioning: the visual tracking feedback module (4) uses a laser to scan the weld with a large aspect ratio (2), collects weld edge information during the scanning process, calculates the weld center position, and sends it to the narrow gap welding robot (3); S4, adjusting the position of the narrow gap welding robot: setting the side of the narrow gap welding robot (3) equipped with the visual tracking feedback module (4) as the welding forward direction, adjusting the lateral offset and the longitudinal offset on the terminal of the visual tracking feedback module (4) according to the relative position relationship between the narrow gap welding robot (3) and the visual tracking feedback module (4), and adjusting the position of the narrow gap welding robot (3); S5. Setting the welding posture of the narrow gap welding robot: according to the curvature change of the large aspect ratio weld (2), a series of narrow gap welding robot welding postures (5) are set on the weld so that the angle between the welding wire and the groove remains consistent during the welding process; S6. Automatic welding using a visual tracking feedback function, using a pulse MIG welding method, the narrow gap welding robot (3) completes automatic welding under the guidance of the visual tracking feedback module (4), and automatically adjusts according to the set welding posture during the welding process; S7, after each weld is completed, the lateral offset and the longitudinal offset on the terminal of the visual tracking feedback module (4) are adjusted, and the position of the narrow gap welding robot (3) is adjusted so that the welding wire can always point to the desired welding position; S8. After welding to a certain depth, the relative position of the visual tracking feedback module (4) and the narrow gap welding robot (3) is adjusted so that the visual tracking feedback module (4) is in an optimal working range.

2. A narrow gap gas shielded welding method based on visual tracking according to claim 1, characterized in that: In the above S1, the depth of the large aspect ratio weld (2) ranges from 50 to 150 mm.

3. The narrow gap gas shielded welding method based on visual tracking according to claim 1 is characterized in that: In S2, the optimal working range of the visual tracking feedback module (4) from the edge of the high aspect ratio weld (2) is 100 to 150 mm.

4. The narrow gap gas shielded welding method based on visual tracking according to claim 1, characterized in that: In the S6, the welding wire is ER80S-G with a diameter of φ1.2 mm, the shielding gas is 78% Ar+22% CO2, the gas flow rate is 15L / min~20L / min, the welding process parameters are current 240A~280A, voltage 22V~28V, and welding speed 20cm / min~35cm / min.

5. The narrow gap gas shielded welding method based on visual tracking according to claim 1, characterized in that: In the above S7, by adjusting the lateral offset and the longitudinal offset on the terminal of the visual tracking feedback module (4), the welding of the 50 mm thick narrow gap weld is completed at one time without adjusting the position of the visual tracking feedback module (4).

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