An automated welding method and apparatus for large ring-shaped member girth welds

Abstract

The application relates to the field of welding and discloses an automatic welding method and device for a large ring-shaped component girth weld, which comprises the following steps: vertically clamping a workpiece on a biaxial positioner with rotary and overturning degrees of freedom; during the welding process, the spatial inclination of the workpiece is adjusted in real time through the biaxial positioner, the included angle between the weld line normal and the direction of gravity is maintained within a preset angle range, the workpiece is uniformly rotated through the biaxial positioner, the weld line sequentially passes through a composite welding head at a fixed spatial position in the circumferential direction, and a welding robot keeps the spatial posture of a welding gun fixed and only compensates the position based on a weld line tracking signal. The application has the beneficial effects that the flat welding state is kept during the whole welding process, the welding robot keeps the posture of the welding gun fixed, only the position compensation is carried out through the weld line tracking signal, the spatial angle of the welding gun does not need to be frequently adjusted, the unified and stable control of the welding parameters is realized, and the overall consistency of the girth weld is ensured.

Description

Technical Field

[0001] This invention relates to the field of welding, and more specifically to an automated welding method and apparatus for circumferential welds of large annular components. Background Technology

[0002] Large ring-shaped components have wide applications in many fields. For example, in the manufacturing process of GIS equipment, the shell is usually made of aluminum alloy to meet the requirements of lightweighting and corrosion resistance. The flange and the cylinder are connected and sealed by a ring weld. This weld not only bears the structural strength function, but also the gas sealing function. Therefore, high requirements are placed on the weld formation quality, internal density, and welding deformation control. Due to the large diameter of the GIS shell and its closed cylindrical structure, the ring weld inevitably undergoes various spatial position changes during the welding process, such as flat welding, vertical welding, and overhead welding. Aluminum alloy has the characteristics of high thermal conductivity, low melting point, strong liquid metal fluidity, and easy formation of porosity, making it difficult to control the stability of the molten pool during the welding process.

[0003] Currently, manual or semi-automatic MIG welding is mostly used in production. This method has a large heat input, obvious welding deformation, and the welding quality is significantly affected by the operator's experience. In the overhead welding position, molten pool collapse and porosity defects are prone to occur, making it difficult to ensure the overall consistency of the circumferential weld and failing to meet the high precision and high stability requirements of large ring components for circumferential welds.

[0004] Traditional robotic welding typically involves fixing the workpiece and having the robot move around it to complete circumferential welding. However, for large GIS shells, the robot's posture changes over a wide range, and the welding torch's spatial angle changes continuously. This causes the molten pool to change constantly due to gravity, making it difficult to uniformly control the welding parameter window and thus failing to achieve stable and high-quality circumferential welding.

[0005] Therefore, existing technologies cannot achieve stable and consistent welding quality of aluminum alloy GIS flange circumferential welds while ensuring a high degree of automation. There is an urgent need for a welding method and device that can stabilize the welding posture, control the stress state of the molten pool, and improve the consistency of the welding process. Summary of the Invention

[0006] To address the aforementioned technical problems, the aim is to provide an automated welding method and apparatus for circumferential welds of large annular components. This method maintains a flat welding state throughout the welding process, with the welding robot keeping the welding torch in a fixed posture. Position compensation is performed solely through weld tracking signals, eliminating the need for frequent adjustments to the welding torch's spatial angle. This achieves unified and stable control of welding parameters, ensuring the overall consistency of the circumferential weld.

[0007] This invention is achieved through the following technical solution:

[0008] An automated welding method for circumferential welds of large annular components includes the following steps: vertically clamping the workpiece on a biaxial positioner with rotational and tilting degrees of freedom; during welding, adjusting the spatial tilt angle of the workpiece in real time using the biaxial positioner to maintain the angle between the weld normal and the direction of gravity within a preset angle range; driving the workpiece to rotate at a uniform speed using the biaxial positioner, causing the weld to pass sequentially through a composite welding head at a fixed spatial position along the circumference; and maintaining the welding torch in a fixed spatial posture using a welding robot that performs position compensation based solely on weld tracking signals.

[0009] The beneficial effects of this invention are that, by vertically clamping the workpiece on a dual-axis positioner with rotational and flipping degrees of freedom, structural support is provided for adjusting the posture of the circumferential weld, breaking the limitations of traditional workpiece fixation or robot bypass. During the welding process, the dual-axis positioner adjusts the workpiece's spatial tilt angle in real time, maintaining the angle between the weld normal and the direction of gravity within the preset range required for flat welding. This ensures that the circumferential weld, which originally required multiple posture changes such as flat welding, vertical welding, and overhead welding, remains in a flat welding state throughout the entire process, completely avoiding defects such as molten pool collapse and porosity that are prone to occur in overhead welding. Simultaneously, it solves the problem of aluminum alloy... Due to its high thermal conductivity and strong fluidity, gold material significantly improves the stability of the weld pool, addressing the issue of molten pool runaway in non-flat welding postures. Simultaneously, the dual-axis positioner drives the workpiece to rotate at a uniform speed, causing the weld seam to pass sequentially through a composite welding head at a fixed spatial position along the circumference. The welding robot maintains a fixed welding torch posture and performs position compensation only through weld seam tracking signals, eliminating the need for frequent adjustments to the welding torch's spatial angle. This achieves stable control of welding parameters, avoiding quality deviations caused by posture fluctuations during traditional robot navigation, improving the degree of welding automation, and ensuring the overall consistency of large circumferential weld seams.

[0010] In some embodiments, welding is performed using a composite heat source consisting of a laser and an electric arc. The laser beam is positioned in front of the welding direction, and the welding torch is positioned behind the welding direction. Because of the use of this composite heat source, with the laser beam positioned in front of the welding direction and the welding torch positioned behind, the laser can preheat the circumferential weld area of ​​large annular components in advance. This reduces the problem of rapid heat loss due to the high thermal conductivity of the component material (such as aluminum alloy). Simultaneously, the electric arc can stabilize the molten pool based on the laser preheating, effectively suppressing porosity defects that are prone to occur during the welding of large annular components. This balances welding efficiency and molten pool stability, overcoming the shortcomings of traditional MIG welding, which involves high heat input and numerous defects.

[0011] In some embodiments, the laser beam forms an angle of 20° to 40° with the welding wire axis of the welding torch, the horizontal distance between the laser spot center and the welding wire extension is 2mm to 4mm, and the laser focus has a negative defocusing amount of -1mm to -3mm relative to the workpiece surface. Due to the spatial configuration of the laser beam in front of the welding torch and the MIG welding torch behind it, and the laser beam angle with the welding wire controlled at 20° to 40°, and the filament spacing controlled at 2mm to 4mm, the laser-induced plasma can preheat the welding wire tip, reducing the arc-starting voltage of the MIG arc. Simultaneously, the MIG arc dilutes the laser plasma cloud, reducing laser reflection loss, and increasing the laser energy absorption rate from approximately 65% ​​for a single laser to over 85%. The deep-penetrating keyhole formed by the laser leader provides a stable transition channel for the MIG droplet, increasing the droplet transition frequency and reducing the spatter rate. The synergistic effect of these two factors achieves both a large penetration depth (laser contribution) and good surface formation (MIG contribution), which cannot be simultaneously obtained by a single heat source.

[0012] In some embodiments, the preset angle range is 0° to 15°. By maintaining the angle between the weld normal and the direction of gravity within the preset angle range of 0° to 15°, the circumferential weld of large annular components can be stably kept in a flat welding posture throughout the entire process. This solves the defects such as molten pool collapse and porosity that are prone to occur in the overhead welding position in traditional welding. At the same time, it avoids the problem of molten pool runaway in non-flat welding postures due to the high fluidity of the component material (such as aluminum alloy), ensuring consistent welding quality at all positions of the circumferential weld of large annular components.

[0013] In some embodiments, the rotational angular velocity ω of the dual-axis positioner and the welding linear velocity v satisfy the following... Where D is the diameter of the workpiece, v is in m / min, and ω is in m / min. The unit of D is mm. By adopting a precise matching relationship between the welding linear velocity v, the positioner angular velocity ω, and the workpiece diameter D, the linear velocity of each point of the weld remains constant during the welding process, regardless of changes in the workpiece diameter. This ensures uniform heat input per unit length of weld, avoiding problems such as uneven penetration, poor forming, and increased porosity caused by fluctuations in linear velocity, and improving the circumferential quality consistency of circumferential welds in large ring components.

[0014] In some embodiments, when the composite heat source initiates the arc, the laser is activated first to form an initial molten pool, and then the welding torch is ignited after a delay of 50ms to 200ms. Because the composite heat source initiates the arc by first activating the laser to form an initial molten pool, and then ignites the welding torch after a delay of 50ms to 200ms, the welding area of ​​the circumferential weld of large annular components can first form a stable initial molten pool through the laser. This avoids problems such as unstable molten pool and arc-ignition defects caused by the rapid thermal conductivity and low melting point of aluminum alloy when the arc is directly initiated, thus ensuring the welding quality during the arc-ignition stage.

[0015] In some embodiments, the composite heat source employs a three-stage stepped energy attenuation during arc termination. When welding reaches 5mm to 10mm in front of the lap closure zone, the first stage simultaneously reduces the laser power, arc current, and wire feeding speed to 70% to 80% of their rated values ​​for 0.3s to 0.5s. The second stage simultaneously reduces the laser power, arc current, and wire feeding speed to 40% to 50% of their rated values ​​for 0.3s to 0.5s. The third stage simultaneously reduces the laser power, arc current, and wire feeding speed to 10% to 30% of their rated values ​​and then stops wire feeding, with the shielding gas shut off after a 1s to 2s delay. By employing a three-stage stepped energy decay during arc termination using a composite heat source, and strictly controlling the energy reduction, duration, and shielding gas shut-off delay at each stage, the molten pool in the arc termination stage of the circumferential weld of large annular components can be slowly cooled and fully filled. This effectively avoids defects such as arc craters and cracks that are prone to occur during arc termination. At the same time, the delayed shut-off of the shielding gas can prevent the high-temperature weld from being oxidized by air, further improving the integrity and reliability of the welded joint and solving the problem of numerous defects in traditional arc termination methods.

[0016] In some embodiments, the position compensation includes: acquiring weld contour images in real time using a laser vision sensor installed at the end of the welding robot to obtain the deviation of the actual weld trajectory from a preset path; the control system calculates the lateral and height offsets that the welding torch needs to compensate for, and drives the welding robot to adjust its position within ±2mm in the lateral and height directions to maintain the alignment accuracy between the welding torch and the weld. This ensures that the welding torch is always precisely aligned with the circumferential weld of the large annular component, avoiding problems such as weld offset and poor forming caused by workpiece clamping deviations and minor workpiece deformation during welding, further guaranteeing the welding accuracy and overall consistency of the circumferential weld of the large annular component.

[0017] The present invention also provides an apparatus for implementing an automated welding method for the circumferential weld of a large annular component, comprising a dual-axis positioner, a welding robot, and a control system. The dual-axis positioner is used to carry the workpiece and includes a rotary axis and a tilting axis. The rotary axis is used to drive the workpiece to rotate at a uniform speed, and the tilting axis is used to adjust the spatial tilt angle of the workpiece in real time. A composite welding head is installed at the end of the welding robot. The composite welding head includes a welding torch and a laser. In the working state, the welding torch is located behind the welding direction, and the laser beam is located in front of the welding direction. The control system is connected to the dual-axis positioner, the welding robot, the laser power supply, and the arc power supply signals respectively, and is used to coordinate the control of the rotary axis, the tilting axis, the welding robot, and the composite heat source. By employing a device structure consisting of a dual-axis positioner, a welding robot, and a control system, and with the dual-axis positioner's rotary axis driving the large annular component to rotate at a uniform speed and its flipping axis adjusting the workpiece's spatial tilt angle in real time, the welding robot's end-effector is equipped with a laser and a welding torch. The control system coordinates the operation of each component, enabling the device to precisely implement the welding method and achieve full-process flat welding of the circumferential weld seam of the large annular component. This effectively solves the drawbacks of traditional manual, semi-automatic, and traditional robot welding, balancing the degree of welding automation and welding quality, and providing equipment support for the stable welding of the circumferential weld seam of large annular components.

[0018] In some embodiments, the tilting shaft is connected to the workpiece clamping mechanism via a cantilever. The cantilever is L-shaped, with one end connected to the output end of the tilting shaft and the other end connected to the rotary shaft. The output end of the rotary shaft is connected to the workpiece, and the rotation center of the workpiece coincides with the axis of the rotary shaft. Because the L-shaped cantilever connects the tilting shaft and the rotary shaft in series and ensures that the rotation center of the workpiece coincides with the axis of the rotary shaft, the overall center of gravity of the rotary shaft and the workpiece can smoothly transition when the tilting shaft drives the cantilever to tilt, and the rotation axis always remains coaxial with the geometric center of the workpiece. This eliminates additional vibration and attitude drift caused by eccentric torque, ensuring the uniformity of workpiece rotation and the repeatability of the weld trajectory during welding. This provides a structural basis for achieving stable welding of circumferential welds within a preset small angle range.

[0019] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0020] 1. Maintaining a flat welding state throughout the welding process, the welding robot keeps the welding torch in a fixed posture and only uses the weld seam tracking signal for position compensation. There is no need to frequently adjust the spatial angle of the welding torch, which achieves unified and stable control of welding parameters and ensures the overall consistency of the circumferential weld.

[0021] 2. By employing a composite heat source consisting of laser and electric arc for welding, and positioning the laser beam in front of the welding direction and the welding torch behind the welding direction, the laser can preheat the welding area of ​​the circumferential weld of large ring components in advance. This reduces the problem of rapid heat loss caused by the high thermal conductivity of the component material (such as aluminum alloy). At the same time, the electric arc can stabilize the molten pool based on the laser preheating, effectively suppressing the porosity defects that are prone to occur in the welding of large ring components. This balances welding efficiency and molten pool stability, making up for the shortcomings of traditional MIG welding, which has high heat input and many defects.

[0022] 3. By employing a three-stage stepped energy attenuation during arc termination using a composite heat source, and strictly controlling the energy reduction, duration, and shielding gas shut-off delay at each stage, the molten pool in the arc termination stage of the circumferential weld of large annular components can be slowly cooled and fully filled. This effectively avoids defects such as arc craters and cracks that are prone to occur during arc termination. At the same time, the delayed shut-off of the shielding gas can prevent the high-temperature weld from being oxidized by air, further improving the integrity and reliability of the welded joint and solving the problem of numerous defects in traditional arc termination methods. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In the drawings:

[0024] Figure 1 This is a structural diagram of the welding apparatus of the present invention;

[0025] Figure 2 This is a partial structural diagram of the dual-axis positioner in this invention;

[0026] Figure 3 This is a schematic diagram of the welding robot in this invention;

[0027] Figure 4 This is a partial structural diagram of the welding robot in this invention;

[0028] Figure 5 This is a schematic diagram of laser-MIG composite welding in this invention;

[0029] Figure 6 This is a flowchart of the welding process in this invention.

[0030] The attached diagram shows the markings and corresponding component names:

[0031] Control system 10, welding robot 20, welding torch 22, laser 23, end effector rotation axis 24, end effector pitch axis 25, elbow rotation axis 26, elbow pitch axis 27, shoulder pitch axis 28, base rotation axis 29, workpiece 30, dual-axis positioner 31, flip axis 32, cantilever 33, slewing axis 34. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0033] Throughout this specification, references to "an embodiment," "an example," or "an example" mean that a particular feature, structure, or characteristic described in connection with that embodiment or example is included in at least one embodiment of the invention. Therefore, the phrases "an embodiment," "an example," "an example," or "an example" appearing in various places throughout the specification do not necessarily refer to the same embodiment or example. Furthermore, specific features, structures, or characteristics can be combined in one or more embodiments or examples in any suitable combination and / or sub-combination. Moreover, those skilled in the art will understand that the illustrations provided herein are for illustrative purposes and are not necessarily drawn to scale. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0034] In the description of this invention, the terms "front", "rear", "left", "right", "up", "down", "vertical", "horizontal", "high", "low", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the scope of protection of this invention.

[0035] The terms "first," "second," etc., used in this invention are merely for clarity of description and are not intended to limit any order or emphasize importance. Furthermore, the term "connection" as used herein, unless otherwise specified, can refer to a direct connection or an indirect connection via other components.

[0036] Example 1

[0037] like Figures 1-6As shown in the illustration, this embodiment provides an automated welding method for circumferential welds of large annular components, comprising the following steps: The workpiece 30 is vertically clamped on a dual-axis positioner 31 with rotational and flipping degrees of freedom; during welding, the spatial tilt angle of the workpiece 30 is adjusted in real time by the dual-axis positioner 31 to maintain the angle between the weld normal and the direction of gravity within a preset angle range; the workpiece 30 is driven to rotate uniformly by the dual-axis positioner 31, causing the weld to pass sequentially along the circumference through a composite welding head at a fixed spatial position; the welding robot 20 maintains the spatial posture of the welding torch 22 fixed, performing position compensation only based on the weld tracking signal. Fixed posture means that the Euler angle of the welding torch 22 remains unchanged, while position compensation refers to a slight translation of the spatial position of the welding torch 22; the two are not contradictory.

[0038] See Figures 1-4 The workpiece 30 is clamped in an upright position (the axis of the cylinder is perpendicular to the horizontal plane), so that the circumferential weld is located in the horizontal plane. In this state, when the workpiece 30 rotates at a constant speed around the vertical axis, the spatial orientation of any point on the weld relative to the direction of gravity remains unchanged (all are flat welding positions), fundamentally avoiding the problem of periodic changes in weld orientation (flat → upright → overhead → upright → flat) in traditional pipe circumferential welding (workpiece 30 is horizontal and rotates around the horizontal axis). On this basis, the tilt angle of the workpiece 30 is adjusted in real time throughout the welding process by the flipping shaft of the dual-axis positioner 31, further compressing the angle between the weld normal and the direction of gravity to a near-flat welding range of 0° to 15°, so that the force direction of the molten pool is basically consistent with the direction of gravity, and the aluminum liquid will not flow laterally due to the gravity component, thus completely eliminating the risk of molten pool instability in vertical and overhead welding positions.

[0039] See Figure 4 Welding is performed using a composite heat source consisting of a laser 23 and an electric arc. The laser beam 23 is positioned in front of the welding direction, while the welding torch 22 is positioned behind the welding direction. Because of this composite heat source, with the laser beam positioned in front and the torch behind, the laser 23 can preheat the circumferential weld area of ​​large annular components, reducing the rapid heat loss caused by the high thermal conductivity of the component material (such as aluminum alloy). Simultaneously, the electric arc stabilizes the molten pool based on the laser preheating, effectively suppressing porosity defects that are prone to occur during the welding of large annular components. This approach balances welding efficiency and molten pool stability, overcoming the shortcomings of traditional MIG welding, which involves high heat input and numerous defects.

[0040] In some embodiments, the angle between the laser beam 23 and the welding wire axis of the welding torch 22 is 20° to 40°, the horizontal distance between the center of the laser spot 23 and the wire extension is 2mm to 4mm, and the laser focus 23 has a negative defocusing amount of -1mm to -3mm relative to the surface of the workpiece 30. By setting the angle between the laser beam 23 and the welding wire axis of the welding torch 22 to 20° to 40°, controlling the horizontal distance between the center of the laser spot 23 and the wire extension to 2mm to 4mm, and using a negative defocusing amount of -1mm to -3mm relative to the surface of the workpiece 30, the energy of the laser 23 and the electric arc can be precisely coordinated and complement each other. This ensures that the laser 23 fully preheats and increases the penetration depth of the circumferential weld area of ​​the large annular component, while avoiding mutual interference between the laser 23 and the electric arc, ensuring that the welding wire can be accurately fed into the molten pool, further improving the stability of the molten pool and the quality of the weld joint.

[0041] In some embodiments, the rotational angular velocity ω of the biaxial positioner 31 and the welding linear velocity v satisfy the following conditions: Where D is the diameter of the workpiece 30, v is in m / min, and ω is in mm / min. The unit of D is mm. By adopting a precise matching relationship between the welding linear velocity v, the positioner angular velocity ω, and the workpiece diameter D, the linear velocity of each point of the weld remains constant during the welding process, regardless of changes in the workpiece diameter. This ensures uniform heat input per unit length of weld, avoiding problems such as uneven penetration, poor forming, and increased porosity caused by fluctuations in linear velocity, and improving the circumferential quality consistency of circumferential welds in large ring components.

[0042] In some embodiments, when the composite heat source initiates the arc, the laser 23 first activates to form an initial molten pool, and then ignites the welding torch 22 after a delay of 50ms to 200ms. Because the composite heat source initiates the arc by first activating the laser 23 to form an initial molten pool, and then ignites the welding torch 22 after a delay of 50ms to 200ms, the welding area of ​​the circumferential weld of large annular components can first form a stable initial molten pool through the laser 23. This avoids problems such as unstable molten pool and arc-starting defects caused by the rapid thermal conductivity and low melting point of aluminum alloy when the arc is directly initiated, thus ensuring the welding quality during the arc-starting stage.

[0043] In some embodiments, the composite heat source employs a three-stage stepped energy attenuation during arc termination. When welding reaches 5mm to 10mm in front of the lap closure zone, in the first stage, the power of laser 23, arc current, and wire feeding speed are simultaneously reduced to 70% to 80% of their rated values ​​and maintained for 0.3s to 0.5s. In the second stage, the power of laser 23, arc current, and wire feeding speed are simultaneously reduced to 40% to 50% of their rated values ​​and maintained for 0.3s to 0.5s. In the third stage, the power of laser 23, arc current, and wire feeding speed are simultaneously reduced to 10% to 30% of their rated values, and then wire feeding is stopped. The shielding gas is turned off with a delay of 1s to 2s, and the laser 23 is turned off 0.1s to 0.3s after the wire feeding stops, so as to utilize the residual heat of laser 23 for micro-melting repair of the arc crater. By employing a three-stage stepped energy decay during arc termination using a composite heat source, and strictly controlling the energy reduction, duration, and shielding gas shut-off delay at each stage, the molten pool in the arc termination stage of the circumferential weld of large annular components can be slowly cooled and fully filled. This effectively avoids defects such as arc craters and cracks that are prone to occur during arc termination. At the same time, the delayed shut-off of the shielding gas can prevent the high-temperature weld from being oxidized by air, further improving the integrity and reliability of the welded joint and solving the problem of numerous defects in traditional arc termination methods.

[0044] In some embodiments, the position compensation includes: acquiring a weld contour image in real time using a laser 23 vision sensor installed at the end of the welding robot 20 to obtain the deviation of the actual weld trajectory from a preset path; the control system 10 calculates the lateral and height offsets that the welding torch 22 needs to compensate for, and drives the welding robot 20 to adjust its position within ±2mm in the lateral and height directions to maintain the alignment accuracy between the welding torch 22 and the weld. This ensures that the welding torch 22 is always precisely aligned with the circumferential weld of the large annular component, avoiding problems such as weld offset and poor forming caused by workpiece 30 clamping deviation and minor deformation of the workpiece 30 during welding, further guaranteeing the welding accuracy and overall consistency of the circumferential weld of the large annular component.

[0045] Specifically, it also includes a vision sensor. The laser vision sensor is fixed to the output flange of the end-effector 24 or the housing of the composite welding head, and is located in front of or to the side of the composite welding head, ensuring that its field of view always covers the weld area in front of the welding torch 22. The sensor maintains a fixed spatial relative position with the composite welding head and the welding torch 22, that is, the sensor moves with the robot end effector and always points to the weld seam to be welded in front of the welding torch 22 during the welding process to ensure real-time acquisition of the weld seam contour image. The sensor is connected to the control system 10 via a data cable to transmit the acquired weld seam deviation information to the control system, thereby triggering the robot's position compensation action.

[0046] The entire working process is as follows: First, the large annular component (such as a GIS shell) is clamped upright on the dual-axis positioner 31, ensuring that the rotation center of the workpiece 30 coincides with the axis of the positioner's rotation shaft 34; before welding and throughout the welding process, the positioner's tilting shaft adjusts the spatial tilt angle of the workpiece 30 in real time, so that the angle between the normal of the annular weld and the direction of gravity is always maintained at 0° to 15° in a near-flat welding posture; at the same time, the positioner's rotation shaft 34 drives the workpiece 30 to rotate uniformly around the vertical axis, so that the annular weld passes through the laser 23 MIG composite welding head at a fixed spatial position along the circumference; the welding robot 20 keeps the spatial posture of the welding torch 22 fixed, and relies only on the end laser 23 vision sensor to collect the weld contour in real time. The control system 10 calculates the lateral and height deviations and drives the welding torch 22 to perform micro-position compensation within ±2mm to maintain the centering accuracy; when welding starts, the laser 23 The laser beam is emitted first, forming an initial molten pool and keyhole on the surface of the workpiece 30. After a delay of 50ms to 200ms, the MIG arc is ignited and the wire is fed synchronously. The laser 23 is positioned in front of the weld for deep penetration, while the MIG is positioned behind for filling. During the welding process, the control system 10 maintains a constant rotational speed according to the matching relationship between the diameter of the workpiece 30 and the preset linear speed, so that the heat input per unit length of weld is uniform. When the welding reaches 5mm to 10mm in front of the lap closure zone, the arc termination stage performs a three-stage stepped energy decay: in the first stage, the power of the laser 23, the arc current, and the wire feeding speed are simultaneously reduced to 70% to 80% of the rated value and last for 0.3s to 0.5s; in the second stage, they are reduced to 40% to 50% and last for 0.3s to 0.5s; and in the third stage, they are reduced to 10% to 30% and then the wire feeding is stopped. The shielding gas is turned off after a delay of 1s to 2s, thereby completing the high-quality, high-consistency automated welding of the entire circumferential weld.

[0047] Example 2

[0048] See Figures 1-4This embodiment 2 provides an apparatus for implementing an automated welding method for the circumferential weld of a large annular component, comprising a dual-axis positioner 31, a welding robot 20, and a control system 10. The dual-axis positioner 31 is used to carry the workpiece 30 and includes a rotary axis 34 and a tilting axis 32. The rotary axis 34 is used to drive the workpiece 30 to rotate at a uniform speed, and the tilting axis 32 is used to adjust the spatial tilt angle of the workpiece 30 in real time. A composite welding head is installed at the end of the welding robot 20. The composite welding head includes a welding torch 22 and a laser 23. In the working state, the laser beam 23 is located in front of the welding direction, and the welding torch 22 is located behind the welding direction. The control system 10 is connected to the dual-axis positioner 31, the welding robot 20, the laser 23 power supply, and the arc power supply signal, respectively, for coordinating the control of the rotary axis 34, the tilting axis 32, the welding robot 20, and the composite heat source. Because the device structure consists of a dual-axis positioner 31, a welding robot 20, and a control system 10, and the rotation axis 34 of the dual-axis positioner 31 drives the large ring component to rotate at a constant speed, while the flip axis 32 adjusts the spatial tilt angle of the workpiece 30 in real time, the composite welding head at the end of the welding robot 20 is equipped with a laser 23 and a welding torch 22, and the control system 10 coordinates the operation of each component, the device can accurately realize the welding method and achieve full-process flat welding of the circumferential weld of the large ring component. This effectively solves the drawbacks of traditional manual, semi-automatic welding, and traditional robot welding, and balances the degree of welding automation and welding quality, providing equipment support for the stable welding of the circumferential weld of the large ring component.

[0049] In some embodiments, the tilting shaft 32 is connected to the workpiece 30 clamping mechanism via a cantilever 33. The cantilever 33 is L-shaped, with one end connected to the output end of the tilting shaft 32 and the other end connected to the rotary shaft 34. The output end of the rotary shaft 34 is connected to the workpiece 30, and the rotation center of the workpiece 30 coincides with the axis of the rotary shaft 34. Because the L-shaped cantilever 33 connects the tilting shaft 32 and the rotary shaft 34 in series and limits the rotation center of the workpiece 30 to coincide with the axis of the rotary shaft 34, when the tilting shaft 32 drives the cantilever 33 to tilt, the overall center of gravity of the rotary shaft 34 and the workpiece 30 can smoothly transition, and the line of the rotary shaft 34 always remains coaxial with the geometric center of the workpiece 30. This eliminates additional vibration and attitude drift caused by eccentric torque, ensuring the uniformity of the workpiece 30's rotation and the repeatability of the weld trajectory during welding, providing a structural basis for achieving stable welding of the circumferential weld within a preset small angle range.

[0050] The control system 10 adopts an electronic gear synchronization mode, setting the rotary axis 34 of the positioner as the speed master axis (running at a constant angular velocity), and the compensation axis of the welding robot 20 as the position slave axis. When the rotary axis 34 experiences instantaneous speed changes due to load fluctuations, the position command of the slave axis will automatically adjust according to the electronic gear ratio, ensuring that the compensation motion and the rotation of the workpiece 30 are strictly synchronized in time, avoiding centering deviation of the welding torch 22 due to speed asynchrony.

[0051] See Figures 1-3 The welding robot 20 is a six-axis articulated robot, whose structure, from the base to the end effector, includes: a base rotation axis 29, a shoulder pitch axis 28, an elbow pitch axis 27, an elbow rotation axis 26, an end effector pitch axis 25, and an end effector rotation axis 24. The base rotation axis 29 is fixed to the workstation floor or base, and its output end is connected to the shoulder pitch axis 28 to achieve rotation of the entire robot in the horizontal plane. The output end of the shoulder pitch axis 28 is connected to the elbow pitch axis 27 to achieve pitch movement of the shoulder joint in the vertical plane. The output end of the elbow pitch axis 27 is connected to the elbow rotation axis 26 to achieve pitch movement of the elbow joint. The output end of the elbow rotation axis 26 is connected to the end effector pitch axis 25 to achieve axial rotation of the forearm. The output end of the end effector pitch axis 25 is connected to the end effector rotation axis 24 to achieve pitch movement of the wrist joint. A composite welding head 21 is directly fixed to the output flange of the end effector rotation axis 24. Each adjacent axis is connected in series via a rigid housing or connecting arm, forming six rotational degrees of freedom, enabling the welding robot 20 to position the composite welding head 21 to any position and orientation in space. During the welding process, in addition to performing micro-position compensation within a range of ±2mm, each joint axis is coordinated to maintain the spatial orientation of the end welding torch unchanged.

[0052] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An automated welding method for circumferential welds of large annular components, characterized in that, Includes the following steps: The workpiece (30) is clamped on a biaxial positioner (31) with rotational and rotational degrees of freedom; During the welding process, the spatial tilt angle of the workpiece (30) is adjusted in real time by the dual-axis positioner (31) to maintain the angle between the weld normal and the direction of gravity within a preset angle range. The workpiece (30) is driven to rotate at a constant speed by the dual-axis positioner (31), so that the weld passes through the composite welding head with a fixed spatial position in sequence along the circumferential direction. The welding robot (20) keeps the spatial orientation of the welding torch fixed and performs position compensation only based on the weld seam tracking signal.

2. The automated welding method for circumferential welds of large annular components according to claim 1, characterized in that, Welding is performed using a composite heat source consisting of a laser (23) and an electric arc, with the laser beam of the laser (23) located in front of the welding direction and the welding torch (22) located behind the welding direction.

3. The automated welding method for circumferential welds of large annular components according to claim 2, characterized in that, The laser beam has an angle of 20° to 40° with the welding wire axis of the welding gun (22), the horizontal distance between the center of the laser spot (23) and the dry extension of the welding wire is 2mm to 4mm, and the laser focus has a negative defocus amount of -1mm to -3mm relative to the surface of the workpiece (30).

4. The automated welding method for circumferential welds of large annular components according to claim 1, characterized in that, The preset angle range is 0° to 15°.

5. The automated welding method for circumferential welds of large annular components according to claim 1, characterized in that, The rotational angular velocity ω of the biaxial positioner (31) and the welding linear velocity v satisfy the following conditions: Where D is the diameter of the workpiece (30).

6. The automated welding method for circumferential welds of large annular components according to claim 2, characterized in that, When the composite heat source initiates the arc, the laser (23) is activated first to form an initial molten pool, and then the welding torch (22) is ignited after a delay of 50ms to 200ms.

7. The automated welding method for circumferential welds of large annular components according to claim 6, characterized in that, The composite heat source employs a three-stage stepped energy attenuation during arc termination. When welding reaches 5mm to 10mm in front of the lap closure zone, the first stage simultaneously reduces the laser power, arc current, and wire feeding speed to 70% to 80% of their rated values ​​for 0.3s to 0.5s. The second stage simultaneously reduces the laser power, arc current, and wire feeding speed to 40% to 50% of their rated values ​​for 0.3s to 0.5s. The third stage simultaneously reduces the laser power, arc current, and wire feeding speed to 10% to 30% of their rated values ​​and then stops wire feeding, with the shielding gas shut off after a 1s to 2s delay.

8. The automated welding method for circumferential welds of large annular components according to claim 1, characterized in that, The position compensation includes: The weld contour image is acquired in real time by a laser vision sensor installed at the end of the welding robot (20), and the deviation of the actual trajectory of the weld relative to the preset path is obtained. The control system (10) calculates the lateral and height offsets that the welding torch needs to compensate for, and drives the welding robot (20) to adjust its position within ±2mm in the lateral and height directions to maintain the alignment accuracy between the welding torch and the weld.

9. An apparatus for implementing an automated welding method for the circumferential weld of a large annular component as described in any one of claims 1-8, characterized in that, include: A dual-axis positioner (31) is used to carry a workpiece (30). The dual-axis positioner (31) includes a rotary axis (34) and a tilting axis (32). The rotary axis (34) is used to drive the workpiece (30) to rotate at a constant speed, and the tilting axis (32) is used to adjust the spatial tilt angle of the workpiece (30) in real time. The welding robot (20) has a composite welding head (21) installed at its end. The composite welding head (21) includes a welding torch (22) and a laser (23). In the working state, the welding torch (22) is located behind the welding direction, and the beam of the laser (23) is located in front of the welding direction. The control system (10) is connected to the dual-axis positioner (31), welding robot (20), laser power supply and arc power supply signals respectively, and is used to coordinate the control of the rotary axis (34), the flipping axis (32), the welding robot (20) and the composite heat source.

10. The apparatus according to claim 9, characterized in that, The flipping shaft (32) is connected to the workpiece clamping mechanism via a cantilever (33). The cantilever (33) is L-shaped. One end of the cantilever (33) is connected to the output end of the flipping shaft (32), and the other end is connected to the rotary shaft (34). The output end of the rotary shaft (34) is connected to the workpiece (30), and the rotation center of the workpiece (30) coincides with the axis of the rotary shaft (34).

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