Pipe all-position submerged arc welding flux delivery system and control method

Abstract

The application discloses a pipeline all-position submerged arc welding flux conveying system and a control method thereof, and relates to the technical field of submerged arc welding. The pipeline all-position submerged arc welding flux conveying system comprises a welding device, a flux pressure maintaining assembly, an all-position welding module and a visual detection module. The flux pressure maintaining assembly comprises a flux box and a conveying reflux component. The flux box is arranged at the output end of the welding device to form a flux protection cavity around the output end of the welding device. The conveying reflux component comprises at least one positive pressure conveying unit and one negative pressure reflux unit. The positive pressure conveying unit and the negative pressure reflux unit are arranged at two ends in the length direction of the flux box. The technical scheme can dynamically adjust the flux supplement according to the actual welding condition, so as to improve the welding quality in the actual welding process of the submerged arc welding.

Description

Technical Field

[0001] This invention relates to the field of submerged arc welding technology, and in particular to a flux delivery system and control method for all-position submerged arc welding of pipelines. Background Technology

[0002] Submerged arc welding (SAW) has advantages such as deep penetration, high welding efficiency, and stable weld formation, and is widely used in the welding and manufacturing of pressure pipelines, storage tanks, steel structures, and large cylindrical components. Traditional SAW relies primarily on the gravity of the flux itself for flux placement. After falling from the funnel or delivery pipe into the welding area, the flux forms a certain thickness of covering layer in front of the welding torch to achieve arc submersion, air isolation, and stable metallurgical protection.

[0003] However, during all-position welding of pipe circumferential seams, the welding carriage needs to move in a circular motion along the outer wall of the pipe. As the welding position gradually transitions from flat welding to vertical welding and overhead welding, the relationship between the direction of gravity acting on the flux and the normal direction of the weld surface continuously changes. In the vertical welding position, the flux is prone to sliding tangentially along the pipe wall, and in the overhead welding position, it is prone to detaching from the weld area and falling, resulting in problems such as incomplete burial, arc interruption, increased spatter, and insufficient weld protection. Therefore, the traditional submerged arc welding method that relies on gravity to lay the flux is difficult to achieve continuous all-position welding of pipe circumferential seams.

[0004] Therefore, it is necessary to design an all-position submerged arc welding flux delivery and control system that can stably constrain the flux under different working conditions such as flat welding, vertical welding, and overhead welding in pipelines, and can achieve dynamic adjustment of fluid parameters by combining visual inspection and multi-source sensor feedback. Summary of the Invention

[0005] The main objective of this invention is to propose a flux delivery system and its control method for all-position submerged arc welding of pipelines. This aims to solve the problem that traditional submerged arc welding devices and welding methods are difficult to adjust the flux in real time according to the actual welding conditions, and the flux pressure is prone to fluctuation during the welding process, thus affecting the welding quality.

[0006] To achieve the above objectives, the present invention proposes a flux delivery system for all-position submerged arc welding of pipelines, comprising: Welding equipment; A flux holding assembly includes a flux box and a conveying and return component. The flux box is located at the output end of the welding device to form a flux protection cavity around the output end of the welding device. The conveying and return component includes at least one positive pressure conveying unit and one negative pressure return unit. The positive pressure conveying unit and the negative pressure return unit are respectively located at both ends of the flux box along its length to convey flux into the flux protection cavity by positive pressure and to recover excess flux in the flux protection cavity by negative pressure suction. A vent hole is also provided at both ends of the flux box along its length to balance the pressure inside and outside the flux protection cavity. The all-position welding module includes a permanent magnet crawling vehicle body and a tilt sensor. The permanent magnet crawling vehicle body drives the output end of the welding device to crawl along the circumference of the pipe to be welded. The tilt sensor is located on the permanent magnet crawling vehicle body and is used to collect the circumferential tilt angle corresponding to the current welding position in real time. A visual inspection module, located on the permanent magnet crawler vehicle, is used to acquire images and recognize shapes in the flux-covered area in front of the welding torch.

[0007] In one embodiment, the flux box includes a contact end corresponding to the pipe to be welded, and the welding device is located at the middle of the flux box and extends toward the contact end to form a welding area at the contact end. The flux box is provided with multiple guide plates, and the multiple guide plates are inclinedly arranged in the flux protection cavity. When the guide plate extends from one end of the flux protection cavity along the length direction to the middle position of the flux protection cavity, its extended end gradually extends inclinedly toward the welding area.

[0008] In one embodiment, a partition plate is provided inside the flux protection chamber. The partition plate is located between the two inner walls in the width direction of the flux protection chamber to divide the flux protection chamber into a welding protection zone and a recovery and diversion zone in the height direction. The two ends of the welding protection zone and the recovery and diversion zone in the length direction are interconnected. The welding protection zone is connected to the opening of the flux box. The two vent holes are located at the two ends in the length direction of the recovery and diversion zone. The partition plate is provided with clearance holes corresponding to the output end position of the welding device.

[0009] In one embodiment, the negative pressure reflux unit has an isolation mesh at one end located within the flux protection chamber to trap flux particles in the recirculated gas flow; and / or, The vision inspection module includes a front-mounted industrial camera, which is used to acquire flux laying image information.

[0010] In one embodiment, the flux delivery system for all-position submerged arc welding of pipelines further includes a flux storage unit, wherein the input end of the positive pressure delivery unit and the output end of the negative pressure return unit are both connected to the flux storage unit.

[0011] In one embodiment, both the positive pressure delivery unit and the negative pressure return unit include their corresponding pipeline units, and each pipeline unit is equipped with a fluid proportional valve and a pressure sensor.

[0012] This invention also proposes a control method for a flux delivery system for all-position submerged arc welding of pipelines. Based on the flux delivery system for all-position submerged arc welding of pipelines in the above embodiments, the control method for the flux delivery system for all-position submerged arc welding of pipelines specifically includes the following control steps: Step S1: Send an opening command to the fluid proportional valve, use the positive pressure delivery unit to generate an induced airflow to carry the flux particles into the flux box, and simultaneously start the negative pressure return unit to create a controllable negative pressure environment in the flux box. Step S2: Control the welding device to ignite the arc and drive the permanent magnet crawler car to make a circular motion along the outer wall of the pipe. At the same time, the tilt angle sensor monitors the circumferential gravity tilt angle θ of the car body in real time, and the air pressure sensor collects the pipeline pressure P of the positive pressure delivery unit and the negative pressure return unit simultaneously. Step S3: Use the visual inspection module to capture the flux laying image of the welding area in real time, and process and analyze the obtained image to identify continuous and connected flux coverage areas. Step S4: Perform connected component analysis on the flux-covered area, extract the boundary extreme value coordinates, and then calculate the flux laying width W and laying height H; Step S5: Adjust the opening of the fluid proportional valve based on the circumferential gravity inclination angle θ, pipeline pressure P, flux laying width W, flux laying height H, and the current welding posture; where, if the circumferential gravity inclination angle θ corresponds to the flat welding condition, keep the reference flow rate and negative pressure unchanged; if the circumferential gravity inclination angle θ corresponds to the vertical welding condition, increase the positive pressure delivery flow rate; if the circumferential gravity inclination angle θ corresponds to the overhead welding condition, enhance the recovery negative pressure. Step S6: Determine whether the circumferential gravity tilt angle θ, pipeline pressure P, flux laying width W, and flux laying height H are within their corresponding preset process ranges; if the values ​​exceed the set range, adjust the fluid proportional valve opening of the positive pressure conveying unit and the negative pressure return unit; if the values ​​are within the range, maintain the current fluid proportional valve opening of the above units.

[0013] In one embodiment, step S3 specifically includes the following processing steps: The computer host defines the region of interest (ROI) in the acquired image, performs grayscale processing and dual-limit threshold segmentation on the ROI image, thereby obtaining the flux coarse segmentation region; A morphological closing operation is performed on the flux coarse region to connect the fractures between particles and fill the pores, thereby obtaining a continuous and interconnected flux-covered region. Connectivity is marked in the flux-covered area, and isolated areas are eliminated based on area and location constraints, thereby locking in the largest core area.

[0014] In one embodiment, step S4 specifically includes the following sub-steps: For the locked flux-covered area, a parallel-axis circumscribed rectangle operator is applied to extract the boundary extreme value coordinates, thereby obtaining the minimum row coordinate, maximum row coordinate, minimum column coordinate, and maximum column coordinate; Based on the pixel-to-physical conversion coefficient obtained from offline camera calibration, the pixel span is converted into physical dimensions, and then the flux laying width W and height H are calculated.

[0015] In one embodiment, in step S6, if the value exceeds the set range, the opening degree of the fluid proportional valve of the positive pressure delivery unit and the negative pressure return unit is adjusted, including the following adjustment methods: When W is less than the preset lower limit, increase the conveying airflow of the positive pressure conveying unit or decrease the recovery negative pressure of the negative pressure return unit; when W is greater than the preset upper limit, decrease the conveying airflow of the positive pressure conveying unit or increase the recovery negative pressure of the negative pressure return unit. When H is less than the preset lower limit, the flux input of the positive pressure conveying unit is increased; when H is greater than the preset upper limit, the recovery of the negative pressure return unit is enhanced or the flux input of the positive pressure conveying unit is reduced. When P exceeds the preset range, adjust the opening of the fluid proportional control valve of the positive pressure delivery unit and the negative pressure return unit to restore the pipeline pressure to the reference range.

[0016] The technical solution of this invention, through the setting of a flux box, forms a flux protection chamber at the output end of the welding device. This flux protection chamber connects to a positive pressure delivery unit and a negative pressure return unit. During actual welding, the positive pressure delivery unit and the negative pressure return unit work together to maintain stable flux pressure within the flux protection chamber. Furthermore, to accommodate different welding conditions (flat welding, vertical welding, overhead welding), vents are provided at both ends of the flux box corresponding to the positive pressure delivery unit and the negative pressure return unit. During welding condition transitions, the vents coordinate with the delivery and adjustment processes of the positive pressure delivery unit and the negative pressure return unit to maintain stable pressure within the entire flux protection chamber, thereby improving welding quality. Furthermore, based on this, the entire welding system utilizes tilt angle, pressure, and visual morphological characteristics to perform closed-loop adjustment of the fluid proportional control valve, ensuring that the flux layer width, height, and pipeline pressure always tend towards the optimal process range. This improves the continuity, stability, and automation level of all-position submerged arc welding of pipelines, and reduces the risk of defects such as incomplete submersion, slag inclusions, porosity, and molten pool disturbance. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0018] Figure 1 A schematic diagram of a structure of an embodiment of the flux delivery system for all-position submerged arc welding of pipelines provided by the present invention; Figure 2 for Figure 1 Enlarged view of a local structure in the middle; Figure 3 for Figure 1 A schematic diagram showing the positional relationship between the welding device, flux holding assembly, and permanent magnet crawler body in the welding state and the pipeline to be welded (including a schematic diagram of the internal structure of the flux box). Figure 4 for Figure 1 Schematic diagram of the internal structure of the flux box; Figure 5 For based on Figure 1 Flowchart of the control method for the flux delivery system of all-position submerged arc welding in pipelines.

[0019] Explanation of icon numbers: 100. Flux delivery system for all-position submerged arc welding of pipelines; 1. Welding device; 2. Flux pressure holding assembly; 21. Flux box; 211. Flux protection chamber; 212. Contact end; 213. Vent hole; 214. Divider plate; 2141. Clearance hole; 215. Isolation mesh; 216. Guide plate; 22. Conveying and return components; 221. Positive pressure conveying unit; 2211. Positive pressure pipe; 2212. Pressure pump; 2213. Air amplifier; 222. Negative pressure return unit; 2221. Vacuum pump; 2222. Negative pressure pipe; 3. Permanent magnet crawler body; 4. Vision inspection module; 5. Flux storage unit.

[0020] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0022] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0023] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0024] Submerged arc welding (SAW) has advantages such as deep penetration, high welding efficiency, and stable weld formation, and is widely used in the welding and manufacturing of pressure pipelines, storage tanks, steel structures, and large cylindrical components. Traditional SAW relies primarily on the gravity of the flux itself for flux placement. After falling from the funnel or delivery pipe into the welding area, the flux forms a certain thickness of covering layer in front of the welding torch to achieve arc submersion, air isolation, and stable metallurgical protection.

[0025] However, during all-position welding of pipe circumferential seams, the welding carriage needs to move in a circular motion along the outer wall of the pipe. As the welding position gradually transitions from flat welding to vertical welding and overhead welding, the relationship between the direction of gravity acting on the flux and the normal direction of the weld surface continuously changes. In the vertical welding position, the flux is prone to sliding tangentially along the pipe wall, and in the overhead welding position, it is prone to detaching from the weld area and falling, resulting in problems such as incomplete burial, arc interruption, increased spatter, and insufficient weld protection. Therefore, the traditional submerged arc welding method that relies on gravity to lay the flux is difficult to achieve continuous all-position welding of pipe circumferential seams.

[0026] Therefore, it is necessary to design an all-position submerged arc welding flux delivery and control system that can stably constrain the flux under different working conditions such as flat welding, vertical welding, and overhead welding in pipelines, and can achieve dynamic adjustment of fluid parameters by combining visual inspection and multi-source sensor feedback.

[0027] This invention proposes a flux delivery system 100 for all-position submerged arc welding of pipelines.

[0028] Please see Figure 1 , Figure 3 and Figure 4In one embodiment of the present invention, the flux delivery system 100 for all-position submerged arc welding of pipelines includes a welding device 1, a flux pressure holding assembly 2, an all-position welding module, and a vision inspection module 4. The flux pressure holding assembly 2 includes a flux box 21 and a conveying and return component 22. The flux box 21 is located at the output end of the welding device 1 to form a flux protection cavity 211 around the output end of the welding device 1. The conveying and return component 22 includes at least one positive pressure delivery unit 221 and one negative pressure return unit 222. The positive pressure delivery unit 221 and the negative pressure return unit 222 are respectively located at both ends of the flux box 21 along its length, and are respectively used to deliver flux into the flux protection cavity 211 by positive pressure and to remove excess flux from the flux protection cavity 211 by negative pressure suction. The flux box 21 is designed for recycling. Each end of the flux box 21 has a vent 213 to balance the pressure inside and outside the flux protection chamber 211. The all-position welding module includes a permanent magnet crawler body 3 and an tilt sensor. The permanent magnet crawler body 3 drives the output end of the welding device 1 to crawl along the circumference of the pipe to be welded. The tilt sensor is located on the permanent magnet crawler body 3 to collect the circumferential gravity tilt angle corresponding to the current welding position in real time. The vision inspection module 4 is located on the permanent magnet crawler body 3 and is used to collect images and perform shape recognition on the flux-covered area in front of the welding torch.

[0029] Welding device 1 refers to the welding torch assembly for submerged arc welding, with its output end being the welding operation end where the welding wire extends and forms an electric arc. Flux box 21 is a container structure used to form a relatively enclosed space around the welding torch; its bottom surface is adapted to the outer wall of the pipe to be welded, thus creating a flux protection cavity 211 between the welding torch, the molten pool, and the pipe surface. Positive pressure conveying unit 221 refers to a pneumatic conveying device that carries flux particles into the flux box 21 via positive pressure airflow, including an air source, conveying pipeline, and corresponding flow control components. Negative pressure reflux unit 222 refers to a vacuum recovery device that uses negative pressure suction to recover unmelted flux from the welding area to a storage device, including a vacuum pump 2221, recovery pipeline, and a gas-solid separation device. Vent 213 refers to an opening on the wall of the flux box 21 that communicates with the outside atmosphere, used to maintain internal pressure balance during conveying and recovery. Permanent magnet crawler body 3 refers to a moving platform that adheres to the outer wall of the pipe by permanent magnet attraction and can move in a circumferential direction. A tilt sensor is an angle measuring device that can measure the tilt angle of a vehicle body relative to the direction of gravity in real time. Visual inspection module 4 refers to an image acquisition and recognition system composed of an industrial camera, lens, light source, and image processing unit.

[0030] The length direction of the flux box 21 refers to its extension along the welding forward direction. The positive pressure delivery unit 221 is usually located in front of the welding torch to allow for pre-laying of flux, while the negative pressure return unit 222 is located behind the welding torch to recover unmelted flux. "Including at least one" means that the number of positive pressure delivery units 221 and negative pressure return units 222 can be adjusted according to welding process requirements. For example, multiple delivery or recovery channels can be set up in large-diameter or high-welding-speed applications. The word "almost" in "each end is also provided with a vent hole 213" emphasizes that the flux box 21 has one vent hole 213 at each end, forming a symmetrical pressure balance structure. The diameter of the vent hole 213 is usually between 2mm and 8mm to ensure pressure balance while preventing flux particles from escaping from the hole. The circumferential gravity tilt angle refers to the angle of gravity direction corresponding to the position of the permanent magnet crawler body 3 on the circumference of the pipe. Referring to the attached diagram, 0° corresponds to the flat welding position, 90° corresponds to the vertical welding position, and 180° corresponds to the overhead welding position.

[0031] Traditional submerged arc welding relies on the flux's own gravity for placement. In all-position pipeline welding, especially vertical and overhead welding, the flux is prone to slippage or detachment, leading to defects such as incomplete placement and arc interruption. This technical solution solves the problem of flux scattering in non-flat welding positions by using a flux box 21 to form a relatively enclosed flux protection chamber 211 around the welding torch, confining the flux within its effective area. The coordinated operation of the positive pressure delivery unit 221 and the negative pressure return unit 222 achieves continuous flux supply and recycling, ensuring a stable flux layer thickness during welding while preventing flux waste. The vent 213 is one of the key innovations of this solution. When the welding conditions switch between flat welding, vertical welding, and overhead welding, the positive pressure delivery flow rate and negative pressure recovery flow rate need to be dynamically adjusted. If the flux box 21 is completely sealed, internal pressure fluctuations will affect the flux laying state and may even cause box deformation or flux splashing. The vent 213 is connected to the outside atmosphere, allowing the internal pressure to be balanced in a timely manner, ensuring that the pressure in the flux protection chamber 211 is maintained within a reasonable range during flow adjustment. The tilt sensor collects circumferential gravity tilt angle data in real time, providing the control system with a basis for judging the welding posture. The system identifies whether it is currently in flat welding, vertical welding, or overhead welding based on the tilt angle value, and then adjusts the parameters of positive pressure delivery and negative pressure recovery. The vision detection module 4 performs real-time image acquisition and shape recognition of the flux coverage area, extracting flux laying width and height information, enabling the control system to perform closed-loop adjustment according to the actual flux laying state. This multi-dimensional collaborative design of "mechanical constraint + pneumatic balance + sensor feedback" fundamentally solves the technical problem of unstable flux laying in all-position submerged arc welding of pipelines, and improves welding continuity and weld quality.

[0032] In some embodiments, such as Figure 1 , Figure 3 and Figure 4As shown, the flux box 21 includes a contact end 212 corresponding to the pipe to be welded. The welding device 1 is located in the middle of the flux box 21 and extends toward the contact end 212 to form a welding area at the contact end 212. The flux box 21 is provided with a plurality of guide plates 216, and the plurality of guide plates 216 are inclinedly arranged in the flux protection cavity 211. When the guide plate 216 extends from one end of the flux protection cavity 211 along the length direction toward the middle of the flux protection cavity 211, its extended end gradually extends inclined toward the welding area.

[0033] The contact end 212 refers to the part of the bottom surface of the flux box 21 that corresponds to and is close to the outer wall of the pipe to be welded. This end face is usually machined into an arc shape that matches the curvature of the outer wall of the pipe or equipped with a flexible sealing structure to maintain a relative seal between the flux box 21 and the pipe surface during welding. The welding device 1 is located in the middle of the flux box 21, meaning that the axis of the welding torch is basically located in the central area of ​​the flux box 21 along its length. The extension of the welding torch toward the contact end 212 means that the wire extension end and the arc area are near the bottom opening of the flux box 21, thus forming a welding area at the contact end 212. The guide plate 216 is a plate-shaped structure set inside the flux box 21 to guide the flow direction of the gas-solid two-phase flow. It is usually made of thin metal plate or heat-resistant plastic plate with a thickness between 1 and 3 mm. The inclined setting means that the guide plate 216 is arranged at a certain angle relative to the inner wall of the flux box 21 or the initial direction of the airflow, so that the airflow and flux particles form a directional flow on the surface of the guide plate 216.

[0034] The number of "multiple guide plates 216" is typically 3 to 8, with the specific number determined based on the internal dimensions of the flux box 21 and the airflow velocity. The spacing between the guide plates 216 is generally in the range of 10mm to 20mm. "Extending from one end towards the middle along the length direction, the extended end gradually tilts towards the welding area" refers to the guide plates 216 being arranged in a stepped or fan-shaped pattern, forming a flow channel structure that guides flux particles to converge towards the welding area. Specifically, when the flux enters from the front end of the flux box 21, the outermost guide plate 216 has a smaller tilt angle (approximately 15° to 30° relative to the horizontal plane), while the tilt angle of the guide plates 216 gradually increases as they approach the welding area (reaching 45° to 60° for the innermost plates). This allows the flux particles to gradually converge around the welding torch under the combined action of gravity, airflow drag, and the guiding force of the guide plates 216.

[0035] In existing technologies, pneumatically delivered flux is directly sprayed into the welding area through pipelines. The high-speed airflow easily disturbs the molten pool and arc, causing unstable weld formation, increased spatter, and even air entrainment leading to porosity. This technical solution addresses this by incorporating multiple inclined guide plates 216 within the flux box 21 to guide and gradually decelerate the high-speed gas-solid two-phase flow. Flux particles first impact the surface of the outermost guide plate 216, absorbing some of their kinetic energy and deflecting the airflow. They then slide along the surface of the guide plate 216 to the next guide plate 216. Through multiple collisions, reflections, and directional adjustments, the airflow velocity gradually decreases, the flux particle distribution becomes more uniform, and finally, the flux spreads to the welding area at a lower speed and over a wider area. This stepped deceleration and directional spreading mechanism ensures the continuity of flux delivery while avoiding direct impact of the high-speed airflow on the molten pool. The inclined design of the extended end of the guide plate 216 towards the welding area ensures that when flux particles detach from the end of the guide plate 216, their movement direction points towards the welding torch and the surrounding molten pool. This achieves precise flux placement, reduces ineffective accumulation and scattering of flux within the flux box 21, and improves flux utilization. During all-position welding, in vertical and overhead welding conditions, the flux tends to slip or detach due to gravity. The inclined arrangement of the guide plate 216, combined with airflow pressure, creates a forced guiding effect on the flux, partially offsetting the gravitational component. This allows the flux to still effectively cover the welding area, further enhancing the system's adaptability to different welding postures.

[0036] In some embodiments, such as Figure 1 , Figure 2 and Figure 4 As shown, a partition plate 214 is provided inside the flux protection chamber 211. The partition plate 214 is located between the two inner walls in the width direction of the flux protection chamber 211 to divide the flux protection chamber 211 into a welding protection zone and a recovery and diversion zone in the height direction. The two ends of the welding protection zone and the recovery and diversion zone in the length direction are interconnected. The welding protection zone is connected to the opening of the flux box 21. Two vent holes 213 are located at the two ends in the length direction of the recovery and diversion zone. An avoidance hole 2141 is provided on the partition plate 214 corresponding to the output end position of the welding device 1.

[0037] The partition plate 214 refers to a horizontally or nearly horizontally positioned partition plate inside the flux protection chamber 211, dividing the chamber into upper and lower sections in the vertical direction. The welding protection zone is the lower section closest to the pipe surface, directly in contact with the welding torch and molten pool. Flux is primarily deposited in this area to provide protection during the welding process. The recovery and diversion zone is the area above the partition plate 214, mainly used to accommodate the recovery gas flow and unmelted flux, preventing the recovery gas flow from directly impacting the flux layer within the welding protection zone. "Interconnected at both ends in the length direction" means that the partition plate 214 does not completely enclose the welding protection zone and the recovery and diversion zone; instead, it has connecting holes or gaps at the front and rear ends, allowing the gas flow and flux to flow between the two areas, maintaining pressure balance and unobstructed circulation paths. The portion of the welding device 1 located within the flux protection chamber 211 refers to the torch tip, which can pass through the clearance hole 2141 and weld the outer wall of the pipe within the welding protection zone.

[0038] The width direction of the flux protection chamber 211 refers to the transverse direction perpendicular to the welding direction. The partition plate 214 spans the two inner walls in this direction and is usually fixed by welding, bolting, or a snap-fit ​​structure. The height direction refers to the direction perpendicular to the pipe surface. The welding protection zone is located at the lower part close to the pipe surface, and the recovery flow guiding zone is located at the upper part away from the pipe surface. The height of the welding protection zone is usually 20mm to 40mm, and the height of the recovery flow guiding zone is 20mm to 30mm. The height ratio between the two is determined according to the flux layer thickness and the required recovery airflow. "The two vents 213 are located at both ends of the length direction of the recovery flow guiding zone" means that the vents 213 are opened above the partition plate 214 and communicate with the recovery flow guiding zone, but not directly with the welding protection zone. This arrangement allows the vents 213 to balance the pressure while preventing external airflow from directly blowing into the welding protection zone and affecting the flux laying state.

[0039] If the flux protection chamber 211 is a single space, the simultaneous operation of positive pressure delivery and negative pressure recovery can easily lead to turbulence and pressure unevenness within the chamber, resulting in unstable flux laying and the possibility that the recovered airflow may directly disperse the flux layer in the welding area. This technical solution divides the flux protection chamber 211 into a welding protection zone and a recovery and guiding zone using a partition plate 214, achieving the design goals of "functional zoning, airflow isolation, and pressure balance." The welding protection zone is specifically for flux laying and welding operations. Positive pressure-delivered flux relatively stably covers the molten pool within this zone. The recovery and guiding zone serves to guide and buffer the recovered airflow. The recovered negative pressure forms a suction field in this zone, indirectly affecting the welding protection zone through the connecting holes at the front and rear ends of the partition plate 214, preventing strong negative pressure from directly acting on the flux layer surface. The two zones are interconnected along their length, ensuring that flux particles can enter from the front end of the welding protection zone and be drawn into the recovery and guiding zone at the rear end, forming a complete circulation path. Simultaneously, the interconnected structure allows for gas exchange between the two zones, maintaining overall pressure balance. By placing the vent 213 in the recovery and diversion zone rather than the welding protection zone, the outside air enters the flux box 21 and first enters the recovery and diversion zone, mixing with the recovered airflow before indirectly affecting the welding protection zone through the connecting hole. This "isolation and buffer" design avoids direct disturbance of the flux layer by the outside airflow, ensuring the stability of the internal environment of the welding protection zone. A clearance hole 2141 is provided on the partition plate 214 at one end corresponding to the welding device 1, allowing the welding torch to weld the outer wall of the pipe at the contact end 212 through the clearance hole 2141.

[0040] In some embodiments, such as Figure 1 and Figure 2 As shown, the negative pressure reflux unit 222 is provided with an isolation mesh 215 at one end inside the flux protection chamber 211 to trap flux particles in the recovered gas flow; and / or, the vision inspection module 4 includes a front-mounted industrial camera, which is used to collect flux laying image information.

[0041] The isolation mesh 215 refers to a mesh filter material woven from metal wire or heat-resistant fiber, with a mesh size typically between 0.5mm and 2mm. It allows airflow to pass through smoothly while blocking flux particles and welding residues. Interception refers to the physical sieving process that intercepts flux particles in front of the isolation mesh 215, preventing them from entering the recovery pipeline. The front-mounted industrial camera is a digital camera installed in front of or to the side of the welding torch to capture images of the welding area. It typically uses a CCD or CMOS image sensor and possesses protection levels and stability suitable for industrial environments. Flux application image information refers to image data containing features such as the shape, boundaries, width, and height of the flux-covered area.

[0042] The isolation mesh 215 is fixed to the pipe opening or channel inlet at this end, forming the first filtration barrier. The mesh size of the isolation mesh 215 needs to be determined according to the particle size of the flux. Generally, the diameter of submerged arc welding flux particles is between 0.5mm and 2.5mm, and the mesh size of the isolation mesh 215 is selected to be 0.8mm to 1.5mm, which can trap most of the flux particles while ensuring that the airflow resistance is not too large to affect the recovery effect. The expression "and / or" means that this claim covers three situations: only the isolation mesh 215 is set, only the front-mounted industrial camera is included, and both the isolation mesh 215 and the front-mounted industrial camera are set. The "front-mounted" in front-mounted industrial camera means that the camera is installed in front of the welding torch, which can observe the flux laying status in advance and provide predictive information for the control system.

[0043] When recovering flux, the negative pressure reflux unit 222 draws in welding spatter, slag fragments, dust, and a small amount of partially molten flux clumps, in addition to unmelted, intact flux particles. If these impurities directly enter the recovery pipeline, they can easily adhere to the inner wall of the pipeline or accumulate at bends and valves, causing pipeline blockage, reducing recovery efficiency, and in severe cases, leading to a drop in negative pressure or even system failure. This technical solution uses an isolation mesh 215 at the end of the reflux unit. The mesh's sieving action traps flux particles and large impurities within the flux protection chamber 211, allowing only airflow and fine dust to pass through the mesh into the recovery pipeline, thus reducing the risk of pipeline blockage at the source. The trapped flux particles accumulate in front of the mesh under negative pressure. When the accumulation reaches a certain level, some flux will fall back into the welding protection zone or be diverted to the flux collection tank in the recovery diversion zone under gravity. Regular cleaning of the collection tank enables secondary recycling of the flux. The installation of the isolation screen 215 not only improves the reliability of the recycling system, but also extends the service life of the recycling pipeline and vacuum pump 2221, and reduces maintenance costs.

[0044] The front-mounted industrial camera in the vision inspection module 4 can acquire real-time images of the flux-laying area in front of the welding torch. These images contain key information such as flux coverage, flux layer thickness, and flux distribution uniformity. The images acquired by the camera are transmitted via data cable to an industrial control computer or embedded image processing unit. Image processing algorithms extract the geometric features of the flux area and calculate the flux laying width W and height H. These parameters reflect whether the current flux laying status meets process requirements, providing direct basis for the control system to adjust the positive pressure delivery flow and negative pressure recovery flow. Compared with traditional methods relying on experience or post-inspection, the vision inspection module 4 achieves real-time monitoring and quantitative evaluation of the flux laying status, enabling the control system to perform closed-loop adjustments based on the actual laying effect, significantly improving the intelligence level of the welding process and the consistency of weld quality. The installation position and field of view setting of the front-mounted industrial camera must ensure that it covers the flux laying area within a range of 30mm to 100mm in front of the welding torch. The flux status in this area represents the flux supply situation before entering the weld pool and has a predictive effect on welding quality.

[0045] In some embodiments, such as Figure 1 As shown, the flux delivery system 100 for all-position submerged arc welding of pipelines also includes a flux storage unit 5, and the input end of the positive pressure delivery unit 221 and the output end of the negative pressure return unit 222 are both connected to the flux storage unit 5.

[0046] The flux storage unit 5 refers to a container or silo used for storing, temporarily storing, and recycling flux. It is typically a closed or semi-closed structure, capable of holding a certain amount of flux particles. The input end of the positive pressure conveying unit 221 refers to the inlet or suction pipe connection end where the positive pressure conveying unit 221 takes material from the flux storage unit 5. The output end of the negative pressure reflux unit 222 refers to the discharge port or return pipe connection end where the negative pressure reflux unit 222 transports the recovered flux back to the flux storage unit 5. "Both connected to the flux storage unit 5" means that the flux storage unit 5 simultaneously serves as the supply source for the positive pressure conveying unit 221 and the return destination for the negative pressure reflux unit 222, forming a closed-loop circulation path for the flux.

[0047] The capacity of the flux storage unit 5 is determined based on the welding workload and continuous operation time, generally ranging from 5 kg to 50 kg, sufficient to meet the flux requirements for continuous welding for 30 minutes to several hours. The flux storage unit 5 is typically installed in a fixed location outside the permanent magnet crawler trolley body 3 (such as on the ground or an auxiliary support), and is connected to the positive pressure conveying unit 221 and the negative pressure return unit 222 via flexible hoses. The hoses must be flexible and wear-resistant to accommodate the movement of the welding trolley along the circumference of the pipeline. The connection between the input end of the positive pressure conveying unit 221 and the flux storage unit 5 is typically achieved by inserting a suction pipe into the bottom or lower side of the storage unit, using the negative pressure created by compressed airflow in the conveying pipeline to transport the flux from the storage unit to the conveying pipeline. The connection between the output end of the negative pressure return unit 222 and the flux storage unit 5 is typically achieved by connecting a return pipe to the top or upper side of the storage unit.

[0048] If the flux delivery system adopts an open-loop feeding method, where the flux is directly laid from the hopper to the welding area, unmelted flux will scatter or accumulate on the pipe surface, resulting in flux waste and requiring manual cleaning, increasing labor intensity and costs. This embodiment constructs a closed-loop circulation system for flux, consisting of a flux storage unit 5, with the input of the positive pressure delivery unit 221 and the output of the negative pressure return unit 222 connected to it. The flux is transported from the storage unit to the flux box 21 via the positive pressure delivery unit 221, where it is laid in the welding area and participates in welding protection. Unmelted flux is recovered by the negative pressure return unit 222 and returned to the storage unit, achieving flux recycling. This closed-loop design significantly reduces flux consumption (flux recovery rate can reach 80%–95%), lowers welding costs, and avoids workplace pollution caused by unmelted flux scattering, maintaining a clean working environment. The flux storage unit 5 serves as a buffer in the circulation system, balancing flow fluctuations during the conveying and recycling processes. When the conveying flow rate exceeds the recycling flow rate, the flux dosage in the storage unit gradually decreases, and the system can promptly add new flux through the replenishment device. When the recycling flow rate exceeds the conveying flow rate, the flux dosage in the storage unit increases, and the system can adjust the conveying and recycling flow rates according to the material level in the storage unit to maintain dynamic balance.

[0049] In some embodiments, such as Figure 1 As shown, both the positive pressure conveying unit and the negative pressure return unit 222 include their corresponding pipeline units, and each pipeline unit is equipped with a fluid proportional valve (not shown in the figure) and a pressure sensor (not shown in the figure).

[0050] The piping unit refers to the piping system that constitutes the positive pressure delivery unit 221 and the negative pressure return unit 222, including delivery pipes, return pipes, connecting joints, elbows, tees, and other piping components. Piping materials are typically wear-resistant rubber hoses, polyurethane hoses, or stainless steel corrugated pipes. A fluid proportional valve is an electrically controlled valve that can continuously adjust the gas flow rate according to a control signal. It is usually an electric proportional valve or a solenoid proportional valve, and the valve opening can be continuously adjusted within the range of 0% to 100%, with a flow rate adjustment accuracy generally within ±2%. A pressure sensor is a sensor used to measure the gas pressure inside the pipeline in real time.

[0051] "Each includes its corresponding piping unit" means that the positive pressure delivery unit 221 has an independent delivery piping unit, and the negative pressure return unit 222 has an independent recovery piping unit. The two piping units are physically independent and are respectively connected to the flux storage unit 5, the flux box 21, and the corresponding gas source equipment. "Each piping unit is equipped with a fluid proportional valve and a pressure sensor" means that each piping unit is equipped with a fluid proportional valve and a pressure sensor, that is, the system includes at least two fluid proportional valves (one on the positive pressure delivery pipeline and one on the negative pressure recovery pipeline) and two pressure sensors (to monitor the pressure of the delivery pipeline and the pressure of the recovery pipeline, respectively). The fluid proportional valve is usually installed near the gas source end or near the pipeline inlet of the flux storage unit 5 to facilitate the adjustment of the gas flow rate entering the pipeline; the pressure sensor is usually installed downstream of the fluid proportional valve, near the flux box 21 or the load end of the pipeline to facilitate the monitoring of the actual working pressure.

[0052] During all-position submerged arc welding, as the welding position switches between flat, vertical, and overhead welding, the relationship between the direction of gravity acting on the flux and the normal direction of the pipe surface continuously changes, posing different challenges to the stability of flux laying. In flat welding, the flux mainly spreads naturally under gravity, requiring a smaller airflow. In vertical welding, the flux tends to slide along the pipe wall, necessitating increased airflow to provide clamping force. In overhead welding, the flux tends to detach from the pipe wall and fall, requiring increased recovery negative pressure to provide adsorption and lifting force. These changing conditions require the delivery and recovery system to dynamically adjust airflow parameters based on the real-time welding posture. In this embodiment, fluid proportional valves are installed on the positive pressure delivery pipeline and the negative pressure recovery pipeline, allowing independent adjustment of the delivery and recovery flow rates. The control system can send opening adjustment commands to the two fluid proportional valves based on the circumferential gravity tilt angle collected by the tilt sensor, the flux laying width and height calculated by the vision detection module 4, and the pipeline pressure fed back by the pressure sensor, achieving precise matching of the delivery airflow and recovery negative pressure. A pressure sensor monitors pipeline pressure in real time. When the pressure deviates from the target value, the control system can promptly adjust the opening of the fluid proportional valve to form a closed-loop pressure control, avoiding pressure instability caused by fluctuations in the gas source, changes in pipeline resistance, or changes in load. This control architecture of "independent adjustment of dual valves + real-time feedback of dual sensors" enables the system to maintain a dynamic balance in the flux placement during complex and variable all-position welding processes, significantly improving the stability of the welding process and the consistency of weld quality.

[0053] In a specific embodiment, the positive pressure delivery unit includes a pressure pump 2212 and a corresponding positive pressure pipe 2211. The positive pressure pipe 2211 is connected to the flux box 21 and the flux storage unit 5. An air amplifier 2213 is provided on the positive pressure pipe 2211. The pressure pump 2212 and the air amplifier 2213 are connected. After the compressed air from the pressure pump 2212 enters the air amplifier 2213, a high-speed airflow is formed inside it, inducing the surrounding air to participate in the flow, thereby increasing the overall flow rate in the positive pressure pipe 2211 to complete the efficient delivery of flux. The negative pressure return unit 222 includes a vacuum pump 2221 and a negative pressure pipe 2222. One end of the negative pressure pipe 2222 is connected to the other end of the flux box 21 along its length, and the other end of the negative pressure pipe 2222 is connected to the flux storage unit 5. The vacuum pump 2221 can be connected in series in the negative pressure pipe 2222, which can realize the recovery of flux through negative pressure, thereby forming a complete flux circulation system.

[0054] Please refer to the above as well. Figure 5 The present invention also includes a control method for a flux delivery system 100 for all-position submerged arc welding of pipelines. Based on the above-mentioned flux delivery system 100 for all-position submerged arc welding of pipelines, the control method for the flux delivery system 100 for all-position submerged arc welding of pipelines specifically includes the following control steps: Step S1: Send an opening command to the fluid proportional valve, using the positive pressure delivery unit 221 to generate an induced airflow to carry flux particles into the flux box 21, and simultaneously start the negative pressure return unit 222, thereby creating a controllable negative pressure environment within the flux box 21; Step S2: Operate the welding device 1 to ignite the arc, and drive the permanent magnet crawler 3 to move in a circular motion along the outer wall of the pipeline. At the same time, the tilt angle sensor monitors the circumferential gravity tilt angle θ of the trolley in real time, and the pressure sensor simultaneously collects the pipeline pressure P of the positive pressure delivery unit 221 and the negative pressure return unit 222; Step S3: Use the visual inspection module 4 to capture the flux laying image of the welding area in real time, and process and analyze the acquired image to identify continuous and connected flux coverage areas; Step S4: Perform connectivity analysis on the flux coverage area, extract the boundary extreme value coordinates, and then calculate... Step S5: Adjust the opening of the fluid proportional valve based on the circumferential gravity inclination angle θ, pipeline pressure P, flux laying width W, and flux laying height H, and in conjunction with the current welding posture. Specifically, if the circumferential gravity inclination angle θ corresponds to a flat welding condition, maintain the reference flow rate and negative pressure unchanged; if the circumferential gravity inclination angle θ corresponds to a vertical welding condition, increase the positive pressure delivery flow rate; if the circumferential gravity inclination angle θ corresponds to an overhead welding condition, enhance the recovery negative pressure. Step S6: Determine whether the circumferential gravity inclination angle θ, pipeline pressure P, flux laying width W, and flux laying height H are within their corresponding preset process ranges. If the values ​​exceed the set range, adjust the opening of the fluid proportional valves of the positive pressure delivery unit 221 and the negative pressure return unit 222. If the values ​​are within the range, maintain the current fluid proportional valve opening of the aforementioned units.

[0055] The control method uses the submerged arc welding control system as the main actuator. It achieves closed-loop regulation of the flux delivery system by collecting data from multiple sensors, executing image processing algorithms, judging welding conditions, and outputting control commands. "Sending an opening command to the fluid proportional valve" means the control system sends an electrical signal to the fluid proportional valve via a communication interface, causing the valve to adjust from a closed state to a preset opening degree, thus initiating airflow delivery. "Induced airflow" refers to the air amplifier 2213 using compressed air to form a high-speed jet internally, inducing surrounding gas to be entrained and mixed to form an amplified airflow, which carries flux particles into the delivery pipeline. "Controllable negative pressure environment" means the internal pressure of the flux box 21 is lower than atmospheric pressure, and the pressure value can be controlled by adjusting the flow rate of the negative pressure return unit 222. "Arc ignition" refers to the process of establishing an electric arc between the welding wire and the workpiece after the welding torch is energized. "Circumferential gravity tilt angle θ" refers to the angle between the direction of gravity corresponding to the position of the permanent magnet crawler vehicle 3 on the circumference of the pipe and the normal direction of the pipe surface. θ=0° indicates that the vehicle is located at the top of the pipe (flat welding), θ=90° indicates that the vehicle is located on the side of the pipe (vertical welding), and θ=180° indicates that the vehicle is located at the bottom of the pipe (overhead welding). "Pipeline pressure P" includes the pressure P1 of the positive pressure delivery pipeline and the pressure P2 (negative value) of the negative pressure recovery pipeline. "Fluoride coverage area" refers to the continuous area formed by flux particles in the image, which is the target area obtained after separation from the background by image processing algorithms. "Connected component analysis" refers to marking the binarized or segmented image region, identifying the sets of interconnected pixels, and calculating the area, centroid, circumscribed rectangle, and other geometric features of each connected component. "Boundary extreme value coordinates" refers to the minimum row coordinates, maximum row coordinates, minimum column coordinates, and maximum column coordinates of the flux coverage area in the image coordinate system, used to determine the circumscribed rectangle of the region. "Preset process range" refers to the reasonable range of flux laying width, height and pipeline pressure determined through process experiments or experience data.

[0056] Steps S1 to S6 constitute a complete control loop. Steps S1 and S2 are the system initialization and startup phases, steps S3 and S4 are the data acquisition and feature extraction phases, and steps S5 and S6 are the control decision and execution phases. The entire control loop is executed periodically at a certain frequency (e.g., 1Hz to 10Hz) to achieve real-time closed-loop regulation of the flux delivery system. In step S1, "synchronously starting the negative pressure reflux unit 222" means that the positive pressure delivery unit 221 and the negative pressure reflux unit 222 start almost simultaneously, avoiding pressure imbalance inside the flux box 21 caused by starting only one unit. In step S5, "adjusting the fluid proportional valve opening based on the current welding posture" means that the control system determines whether the current welding condition is flat, vertical, or overhead based on the tilt angle θ, and adopts different control strategies for different conditions: in flat welding, the flux spread is relatively stable, and the flow rate is mainly fine-tuned based on W and H; in vertical welding, the flux tends to slide downwards, so the positive pressure delivery flow rate is increased first to provide clamping force; in overhead welding, the flux tends to fall, so the recovery negative pressure is increased first to provide adsorption and lifting force. Step S6 is the core link of closed-loop control. By judging whether the current parameters are within the preset process range, it decides whether to adjust the fluid proportional valve opening. If the parameters are out of range, the adjustment is performed; if the parameters are within range, the current state is maintained, forming a closed-loop mechanism of "deviation detection - control adjustment - deviation elimination".

[0057] Traditional submerged arc welding control methods mainly rely on operators adjusting welding parameters based on experience. They lack quantitative means for monitoring and adjusting flux placement, especially during all-position welding where flux placement changes drastically with welding posture. Manual adjustments are difficult to respond to in a timely manner, easily leading to problems such as uneven flux layer thickness, insufficient or excessive width, affecting weld quality. This control method uses tilt sensors, pressure sensors, and a vision inspection module 4 to achieve multi-dimensional real-time monitoring of welding posture, pipeline pressure, and flux placement. It transforms the previously difficult-to-quantify flux placement "shape" into calculable width W and height H values, providing clear feedback signals to the control system. Steps S1 and S2 complete system startup and data acquisition preparation, ensuring a stable flux protective layer is formed in the flux box 21 before welding begins, preventing arc exposure or spatter due to insufficient flux at the moment of arc ignition. Steps S3 and S4 use visual detection and image processing algorithms to convert the visual information of the flux laying area into quantitative geometric parameters. This algorithm employs morphological closing operations to connect discrete particle regions, utilizes connected component analysis to remove noise, and extracts boundary coordinates using a parallel axis circumscribed rectangle. It can stably extract flux laying features even under strong arc light, spatter, and particle reflection interference at the welding site, demonstrating strong robustness. Step S5 determines the welding posture based on the tilt angle θ and adopts different control strategies, reflecting the design concept of "condition-specific adaptive adjustment," avoiding the poor adaptability of a unified control strategy under different conditions. Step S6 determines whether multiple parameters simultaneously meet the process range requirements, forming multi-variable collaborative control. This ensures that the flux laying width and height meet welding process requirements and that pipeline pressure remains within a safe and reasonable range, avoiding potential parameter instability issues that might occur with single-variable control. The entire control method achieves intelligent closed-loop control of "posture perception—visual feedback—pressure monitoring—multi-variable collaborative adjustment," significantly improving the automation level, welding stability, and weld quality consistency of all-position submerged arc welding in pipelines.

[0058] In some embodiments, step S3 specifically includes the following processing steps: the computer host defines the region of interest (ROI) in the acquired image, performs grayscale processing and dual-limit threshold segmentation on the ROI image to obtain a coarse flux segmentation region; performs morphological closing operation on the coarse flux segmentation region to connect the fractures between particles and fill the holes, thereby obtaining a continuous and connected flux-covered region; marks the flux-covered region as a connected component, and removes isolated regions based on area and position constraints, thereby locking the largest core region.

[0059] The computer host refers to an industrial control computer or embedded image processing unit, responsible for executing image processing algorithms and outputting flux geometric feature parameters. The Region of Interest (ROI) is a rectangular sub-image defined within the complete image, containing the flux-covered area. Cropping the ROI eliminates irrelevant background, reduces computational load, and improves processing speed. Grayscale conversion refers to the process of converting a color RGB image to a single-channel grayscale image. The conversion formula is typically Gray = 0.299R + 0.587G + 0.114B, or by averaging the R, G, and B channels. Dual-threshold segmentation involves setting a lower threshold T1 and an upper threshold T2, marking pixels with grayscale values ​​within the T1-T2 range as the target (flux), and marking the remaining pixels as background, thus achieving initial separation between the target and background. The flux coarse segmentation region refers to the preliminary flux target region obtained after threshold segmentation. This region may contain inter-particle fractures, internal pores, and noise interference. Morphological closing refers to a combination of morphological operations: first dilation, then erosion. Dilation connects neighboring regions and fills small holes, while erosion restores the expansion caused by dilation. The combination maintains the overall shape of the region while achieving internal connectivity. Connected component labeling involves marking and numbering interconnected pixel sets in a binary image; each connected component represents an independent target region. Area constraint refers to eliminating noise regions that are too small based on a reasonable area range for flux coverage (e.g., ≥500 pixels or ≥1000 mm²). Position constraint refers to eliminating abnormal regions that deviate from their expected position in the image (e.g., located in the image center or within a certain range from the welding torch). The largest core region is the largest connected component after removing noise and abnormal regions; this region represents the true main flux coverage band.

[0060] The definition of the Region of Interest (ROI) is usually performed by operators during system initialization based on the camera installation position and field of view. The row and column range of the ROI (e.g., rows 200-800, columns 300-1000) is stored in the control program, and subsequent image processing directly calls these ROI parameters for cropping. The T1 and T2 values ​​for dual-limit threshold segmentation need to be adjusted and determined according to the welding site lighting conditions and the reflective characteristics of the flux particles. T1 is usually set as the lower limit of the flux particle grayscale value (excluding dark areas such as pipe surfaces and shadows), and T2 is set as the upper limit of the flux particle grayscale value (excluding strong arc light, high-brightness spatter, etc.). Typical values ​​are T1 = 80-120 and T2 = 180-220. The shape and size of the structuring element in morphological closing operations are key algorithm parameters. Circular structuring elements are suitable for processing granular targets. The radius determines the connection and filling capabilities. If the radius is too small (e.g., 1-2 pixels), the connection effect is not obvious; if the radius is too large (e.g., more than 10 pixels), irrelevant areas may be incorrectly connected. Typical values ​​are 3-7 pixels in radius. The area threshold setting after connecting component labeling needs to be determined based on the actual size of the flux-spreading area and the image resolution. For example, if the flux-spreading width is 60mm to 80mm and the height is 10mm to 15mm, it corresponds to approximately 500×100 pixels in the image (converted according to the calibration coefficient), and the area is approximately 50,000 pixels. Then, the area threshold can be set to 500 to 1,000 pixels. Connecting components smaller than this threshold are considered noise and are removed.

[0061] The submerged arc welding (SAW) environment is complex. The flux particles have rough surfaces and uneven reflections. Arc light, spatter, pipe surface reflections, and shadows severely interfere with image acquisition. Traditional edge detection algorithms (such as the Canny and Sobel operators) often only extract discrete, fragmented edge points, making it difficult to form continuous flux region contours. Furthermore, they are sensitive to noise and interference, leading to unstable extracted flux boundaries. This embodiment employs a combined strategy of "ROI clipping—threshold segmentation—morphological closing operation—connected component filtering," fully considering the actual interference factors at the welding site and exhibiting strong robustness. ROI clipping first eliminates irrelevant background at the image edges (such as the permanent magnet trolley structure, the far end of the pipe, and the surrounding environment), allowing subsequent processing to focus on the flux-laying area and avoiding misidentification caused by background interference. Dual-threshold segmentation utilizes the characteristic range of flux particle grayscale values ​​to initially separate the flux from the pipe surface, shadows, and arc light. Compared to single-threshold segmentation, dual-threshold segmentation can more accurately define the target range and improve segmentation accuracy. Morphological closing operations are the core innovation of this algorithm. Addressing the image fragmentation problem caused by gaps and uneven reflection between flux particles, dilation operations bridge and connect adjacent particle regions, while erosion operations restore region boundaries, merging previously discrete particle points into continuous sheet-like regions that represent the overall flux coverage. Connectivity labeling and filtering further eliminate isolated noise areas caused by arc light, spatter, and small reflections. Area constraints (retaining large areas) and position constraints (retaining areas at expected locations) lock in the true main flux coverage band, ensuring the accuracy of subsequent geometric feature extraction. This multi-level processing strategy progressively eliminates interference and purifies the target, resulting in a flux coverage area with clear boundaries and continuous shape, accurately reflecting the actual flux deployment state and providing reliable visual feedback signals to the control system.

[0062] In some embodiments, step S4 specifically includes the following sub-steps: for the locked flux coverage area, a parallel axis circumscribed rectangle operator is applied to extract the boundary extreme value coordinates, thereby obtaining the minimum row coordinate, maximum row coordinate, minimum column coordinate and maximum column coordinate; based on the pixel-to-physical conversion coefficient obtained from the offline camera calibration, the pixel span is converted into physical size, and then the flux laying width W and height H are calculated.

[0063] The parallel-axis circumscribed rectangle operator is an image processing operator that calculates the smallest circumscribed rectangle of the target region parallel to the coordinate axes. In the Halcon library, it corresponds to the `smallest_rectangle1` operator, and in the OpenCV library, it can be implemented using the `boundingRect` function. The operator takes the target region (connected region or contour) as input and outputs the row and column boundary coordinates of the circumscribed rectangle. The boundary extreme coordinates include: the smallest row coordinate (Row). min (Row coordinates of the topmost pixel in the target region), maximum row coordinates (Row)max (Row coordinates of the bottommost pixel in the target region), minimum column coordinate Col min (Column coordinates of the leftmost pixel in the target region), maximum column coordinate Col max (Column coordinates of the rightmost pixel in the target area). Offline camera calibration refers to establishing the correspondence between image pixel coordinates and actual physical dimensions before system use, through calibration boards or physical measurements. The calibration result is a pixel-to-physical conversion coefficient. The pixel-to-physical conversion coefficient includes the width direction coefficient kW (unit: mm / pixel) and the height direction coefficient kh (unit: mm / pixel), representing the actual physical size corresponding to one pixel in the image. Pixel span refers to the pixel size of the target area in the image; the width direction pixel span = Col. max -Col min Pixel span in height direction = Row max -Row min or Row max -Row ref (Row) ref (Based on the reference row coordinates).

[0064] The parallel-axis circumscribed rectangle operator is simple and fast to calculate. Compared to the minimum area circumscribed rectangle or the rotated rectangle, the parallel-axis circumscribed rectangle does not require calculation of rotation angles or complex geometric transformations, making it particularly suitable for real-time control scenarios. However, the disadvantage of the parallel-axis circumscribed rectangle is that when the target area is tilted, the area of ​​the circumscribed rectangle is large, and the boundary coordinates may not be accurate enough. Therefore, this operator is suitable for situations where the principal axis direction of the target area is basically consistent with the image coordinate axis direction. For pipe circumferential welding, the permanent magnet crawler body 3 has a relatively fixed posture relative to the pipe, and the length direction of the flux laying area is basically parallel to the image column direction, which meets the applicable conditions of the parallel-axis circumscribed rectangle. The calibration method for pixel-to-physical conversion coefficients is typically as follows: Place a calibration object of known size (e.g., a rectangular metal sheet 50mm wide and 10mm high) inside the flux box 21, acquire an image, and measure the pixel size of the calibration object in the image (e.g., 420 pixels wide and 85 pixels high). Then, kw = 50mm / 420pixel ≈ 0.119mm / pixel, kh = 10mm / 85pixel ≈ 0.118mm / pixel. Calibration must be performed at the same camera mounting position and working distance as the actual welding to ensure the accuracy of the calibration coefficients. Reference Row Coordinate ref This refers to the row coordinates of the pipe surface or weld reference line in the image, used to calculate the flux layup height H. Since the flux layup height refers to the thickness of the flux layer on the pipe surface in the normal direction, it needs to be based on the pipe surface. Therefore, Row... ref Typically, this is determined by locating the pipe surface in an image (e.g., Row). ref=600 indicates that the 600th row of the image corresponds to the surface of the pipe.

[0065] The flux spread width W and height H are key parameters for evaluating the flux spread status. W reflects the coverage area of ​​the flux in the transverse direction (perpendicular to the welding direction) of the weld, and H reflects the thickness of the flux layer. In traditional welding processes, these two parameters are difficult to measure in real time, and operators can only rely on visual estimation, lacking quantitative basis. This control method uses visual detection and image processing algorithms to transform the visual features of the flux-covered area into calculable geometric dimensions, providing quantitative feedback signals for the control system. The core of step S4 is coordinate extraction and size conversion. The parallel axis circumscribed rectangle operator can quickly and accurately extract the boundary extreme coordinates of the flux-covered area. These four coordinate values ​​define the position and range of the flux-covered area in the image. The column span Col is calculated... max -Col min Multiply by the width conversion factor kW to obtain the physical dimension of the flux layup width W; calculate the row span Row. max -Row ref Multiplying this by the height conversion factor kh yields the physical dimension of the flux placement height H. This conversion method is simple and direct, with minimal computational load, and can be completed within milliseconds, meeting real-time control requirements. It is worth noting that the calculation of the flux placement height H uses Row... max -Row ref Instead of Row max -Row min The reason is Row min The top boundary of the flux-covered area may fluctuate significantly due to irregular flux buildup. (Row) ref Representing the pipe surface reference, the flux layup height should be measured upwards from the pipe surface to the top of the flux accumulation; therefore, a Row is used. max -Row ref This method can more accurately reflect the actual thickness of the flux layer. The W and H values ​​calculated by this method not only reflect the overall coverage of the flux layer but also indirectly reflect the thickness distribution of the flux layer, providing a reliable basis for the control system to determine whether the flux layer meets the process requirements.

[0066] In some embodiments, in step S6, if the value exceeds the set range, the opening of the fluid proportional valves of the positive pressure delivery unit 221 and the negative pressure return unit 222 is adjusted, including the following adjustment methods: when W is less than the preset lower limit, the delivery airflow of the positive pressure delivery unit 221 is increased or the recovery negative pressure of the negative pressure return unit 222 is decreased; when W is greater than the preset upper limit, the delivery airflow of the positive pressure delivery unit 221 is decreased or the recovery negative pressure of the negative pressure return unit 222 is increased; when H is less than the preset lower limit, the flux input of the positive pressure delivery unit 221 is increased; when H is greater than the preset upper limit, the recovery of the negative pressure return unit 222 is enhanced or the flux input of the positive pressure delivery unit 221 is decreased; when P exceeds the preset range, the opening of the fluid proportional control valves of the positive pressure delivery unit 221 and the negative pressure return unit 222 is adjusted to restore the pipeline pressure to the reference range.

[0067] Step S6 is the execution stage of closed-loop control. Based on the flux laying width W and height H calculated in step S4, and the pipeline pressure P collected by the air pressure sensor, it is determined whether each parameter is within the preset process range. If the parameters deviate from the process range, the opening of the fluid proportional valve is adjusted according to the direction and degree of deviation to bring the parameters back to the process range, thereby achieving closed-loop stable control of the flux laying state. "Increasing the conveying airflow of the positive pressure conveying unit 221" means increasing the opening of the fluid proportional valve of the positive pressure conveying pipeline, allowing more compressed air to enter the conveying pipeline, increasing the induced airflow output by the air amplifier 2213, carrying more flux particles into the flux box 21, or increasing the conveying airflow speed, thus increasing the flux laying width. "Reducing the recovery negative pressure of the negative pressure return unit 222" means reducing the opening of the fluid proportional valve of the negative pressure return pipeline, reducing the pumping volume of the vacuum pump 2221, weakening the recovery negative pressure, reducing the speed at which the flux is sucked away, leaving more flux in the flux box 21, and increasing the flux laying width. "Increasing the flux input to the positive pressure conveying unit 221" refers to increasing the opening of the fluid proportional valve 1 or adjusting the discharge device of the flux storage unit 5 (such as the rotation speed of the star-shaped unloading valve) to increase the amount of flux entering the flux box 21 per unit time, thus increasing the flux layer thickness. "Enhancing the recovery of the negative pressure return unit 222" refers to increasing the opening of the fluid proportional valve 2 to enhance the recovery negative pressure, allowing the flux to be drawn away more quickly and reducing the flux layer thickness. "Restoring the pipeline pressure to the reference range" refers to adjusting the opening of the fluid proportional valve to bring the positive pressure conveying pipeline pressure P1 and the negative pressure recovery pipeline pressure P2 back to the preset target ranges (e.g., P1 target range 20kPa-40kPa, P2 target range -30kPa to -50kPa).

[0068] The preset lower and upper limits of W are determined according to the welding process requirements. Typically, the lower limit of W is the weld width + 20mm (to ensure the flux completely covers the weld), and the upper limit of W is the weld width + 40mm (to avoid excessive flux coverage, waste, and impact on adjacent areas). For example, if the weld width is 40mm, the target range for W is 60mm to 80mm. The preset lower and upper limits of H are also determined according to the welding process. Submerged arc welding requires a flux layer thickness sufficient to bury the arc and provide adequate protection and slag removal performance, but excessive thickness will affect heat input and weld formation. A typical target range for H is 10mm to 15mm. The preset range of P needs to ensure the normal operation of the delivery and recovery system. Too low a pressure in the positive pressure delivery pipeline will result in insufficient flux delivery, while too high a pressure may disturb the molten pool. A typical target range for P1 is 20kPa to 40kPa. Too low a pressure (absolute value) in the negative pressure recovery pipeline will result in insufficient recovery efficiency, while too high a pressure may excessively draw away flux or cause excessive pipeline load. A typical target range for P2 is -30kPa to -50kPa. The adjustment methods include unidirectional and bidirectional adjustment. Unidirectional adjustment refers to adjusting only one of the positive pressure delivery unit 221 or the negative pressure return unit 222, while bidirectional adjustment refers to adjusting both simultaneously. For example, when W is less than the lower limit, one can choose to "increase the positive pressure delivery airflow" or "decrease the recovery negative pressure", or both can be performed simultaneously. The specific selection is determined based on the current fluid proportional valve opening margin and control strategy.

[0069] The flux laying width W, height H, and pipeline pressure P are interrelated parameters. W is mainly affected by the balance between the positive pressure delivery flow rate and the negative pressure recovery flow rate. When the delivery flow rate is greater than the recovery flow rate, flux accumulates in the flux box 21, and both W and H increase. When the recovery flow rate is greater than the delivery flow rate, flux is absorbed more quickly, and both W and H decrease. H is also affected by the flux delivery rate (the mass of flux entering the flux box 21 per unit time); the higher the delivery rate, the larger H. P reflects the working state of the airflow system. P1 is positively correlated with the delivery flow rate, and P2 (absolute value) is positively correlated with the recovery flow rate. This control method sets adjustment strategies for the three parameters W, H, and P respectively, considering the main influencing factors of each parameter and providing multiple adjustment means through "OR" relationships, thereby enhancing the flexibility and robustness of the control. When W is less than the lower limit, it indicates that the flux layer is insufficient, and the flux may be exposed on both sides of the weld or the flux coverage may be uneven. In this case, the positive pressure conveying airflow can be increased to allow more flux to enter and spread to a wider area, or the recovery negative pressure can be reduced to reduce the rate at which the flux is sucked away. Both methods can increase the amount of flux in the flux box 21 and expand the layer width. When W is greater than the upper limit, it indicates that the flux layer is too wide, causing waste or affecting visual inspection. In this case, the conveying airflow can be reduced to decrease the flux input, or the recovery negative pressure can be increased to accelerate flux recovery and reduce the amount of flux in the flux box 21. When H is less than the lower limit, it indicates that the flux layer is too thin, and the arc may be exposed or insufficiently protected. In this case, the flux input needs to be increased, mainly by increasing the flow rate of the positive pressure conveying unit 221 or adjusting the discharge device. When H is greater than the upper limit, it indicates that the flux layer is too thick, which may affect the welding heat input or cause flux accumulation. In this case, recovery needs to be enhanced or conveying reduced to reduce flux accumulation in the flux box 21. When P exceeds the range, it indicates an abnormal operating state of the airflow system. An excessively high P1 may cause disturbance to the molten pool, while an excessively low P1 may result in insufficient delivery. An excessively high P2 (absolute value) may indicate excessive recovery, while an excessively low P2 (absolute value) may indicate insufficient recovery. The pressure needs to be restored to the reference range by adjusting the opening of the fluid proportional valve to ensure safe and stable system operation. This multi-parameter, multi-strategy closed-loop control method can cope with complex operating conditions during all-position welding, achieving dynamic optimization of flux placement and significantly improving welding quality and process stability.

[0070] The above description is merely an exemplary embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention specification and drawings under the technical concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A flux delivery system for all-position submerged arc welding of pipelines, characterized in that, include: Welding equipment; A flux holding assembly includes a flux box and a conveying and return component. The flux box is located at the output end of the welding device to form a flux protection cavity around the output end of the welding device. The conveying and return component includes at least one positive pressure conveying unit and one negative pressure return unit. The positive pressure conveying unit and the negative pressure return unit are respectively located at both ends of the flux box along its length to convey flux into the flux protection cavity by positive pressure and to recover excess flux in the flux protection cavity by negative pressure suction. A vent hole is also provided at both ends of the flux box along its length to balance the pressure inside and outside the flux protection cavity. The all-position welding module includes a permanent magnet crawling vehicle body and a tilt sensor. The permanent magnet crawling vehicle body drives the output end of the welding device to crawl along the circumference of the pipe to be welded. The tilt sensor is located on the permanent magnet crawling vehicle body and is used to collect the circumferential tilt angle corresponding to the current welding position in real time. A visual inspection module, located on the permanent magnet crawler vehicle, is used to acquire images and recognize shapes in the flux-covered area in front of the welding torch.

2. The flux delivery system for all-position submerged arc welding of pipelines according to claim 1, characterized in that, The flux box includes a contact end corresponding to the pipe to be welded, and the welding device is located in the middle of the flux box and extends toward the contact end to form a welding area at the contact end. The flux box is provided with multiple guide plates, and the multiple guide plates are inclinedly arranged in the flux protection cavity. When the guide plate extends from one end of the flux protection cavity along the length direction to the middle position of the flux protection cavity, its extended end gradually extends inclinedly toward the welding area.

3. The flux delivery system for all-position submerged arc welding of pipelines according to claim 1, characterized in that, The flux protection chamber is provided with a partition plate, which is located between the two inner walls in the width direction of the flux protection chamber to divide the flux protection chamber into a welding protection zone and a recovery and diversion zone in the height direction. The two ends of the welding protection zone and the recovery and diversion zone in the length direction are interconnected. The welding protection zone is connected to the opening of the flux box, and the two vent holes are located at the two ends of the recovery and diversion zone in the length direction. The partition plate is provided with clearance holes corresponding to the output end position of the welding device.

4. The flux delivery system for all-position submerged arc welding of pipelines according to claim 1, characterized in that, The negative pressure reflux unit is equipped with an isolation mesh at one end within the flux protection chamber to trap flux particles in the recirculated gas flow; and / or, The vision inspection module includes a front-mounted industrial camera, which is used to acquire flux laying image information.

5. The flux delivery system for all-position submerged arc welding of pipelines according to claim 1, characterized in that, The flux delivery system for all-position submerged arc welding of pipelines also includes a flux storage unit, and the input end of the positive pressure delivery unit and the output end of the negative pressure return unit are both connected to the flux storage unit.

6. The flux delivery system for all-position submerged arc welding of pipelines according to claim 1, characterized in that, Both the positive pressure delivery unit and the negative pressure return unit include their corresponding pipeline units, and each pipeline unit is equipped with a fluid proportional valve and a pressure sensor.

7. A control method for a flux delivery system for all-position submerged arc welding of pipelines, based on the flux delivery system for all-position submerged arc welding of pipelines as described in any one of claims 1-6, characterized in that, The control method for the flux delivery system of the pipeline all-position submerged arc welding specifically includes the following control steps: Step S1: Send an opening command to the fluid proportional valve, use the positive pressure delivery unit to generate an induced airflow to carry the flux particles into the flux box, and simultaneously start the negative pressure return unit to create a controllable negative pressure environment in the flux box. Step S2: Control the welding device to ignite the arc and drive the permanent magnet crawler car to make a circular motion along the outer wall of the pipe. At the same time, the tilt angle sensor monitors the circumferential gravity tilt angle θ of the car body in real time, and the air pressure sensor collects the pipeline pressure P of the positive pressure delivery unit and the negative pressure return unit simultaneously. Step S3: Use the visual inspection module to capture the flux laying image of the welding area in real time, and process and analyze the obtained image to identify continuous and connected flux coverage areas. Step S4: Perform connected component analysis on the flux-covered area, extract the boundary extreme value coordinates, and then calculate the flux laying width W and laying height H; Step S5: Adjust the opening of the fluid proportional valve based on the circumferential gravity inclination angle θ, pipeline pressure P, flux laying width W, flux laying height H, and the current welding posture; where, if the circumferential gravity inclination angle θ corresponds to the flat welding condition, keep the reference flow rate and negative pressure unchanged; if the circumferential gravity inclination angle θ corresponds to the vertical welding condition, increase the positive pressure delivery flow rate; if the circumferential gravity inclination angle θ corresponds to the overhead welding condition, enhance the recovery negative pressure. Step S6: Determine whether the circumferential gravity tilt angle θ, pipeline pressure P, flux laying width W, and flux laying height H are within their corresponding preset process ranges; if the values ​​exceed the set range, adjust the fluid proportional valve opening of the positive pressure conveying unit and the negative pressure return unit; if the values ​​are within the range, maintain the current fluid proportional valve opening of the above units.

8. The control method for the flux delivery system of all-position submerged arc welding of pipelines as described in claim 7, characterized in that, Step S3 specifically includes the following processing steps: The computer host defines the region of interest (ROI) in the acquired image, performs grayscale processing and dual-limit threshold segmentation on the ROI image, thereby obtaining the flux coarse segmentation region; A morphological closing operation is performed on the flux coarse region to connect the fractures between particles and fill the pores, thereby obtaining a continuous and interconnected flux-covered region. Connectivity is marked in the flux-covered area, and isolated areas are eliminated based on area and location constraints, thereby locking in the largest core area.

9. The control method for the flux delivery system of all-position submerged arc welding of pipelines as described in claim 7, characterized in that, Step S4 specifically includes the following sub-steps: For the locked flux-covered area, a parallel-axis circumscribed rectangle operator is applied to extract the boundary extreme value coordinates, thereby obtaining the minimum row coordinate, maximum row coordinate, minimum column coordinate, and maximum column coordinate; Based on the pixel-to-physical conversion coefficient obtained from offline camera calibration, the pixel span is converted into physical dimensions, and then the flux laying width W and height H are calculated.

10. The control method for the flux delivery system of all-position submerged arc welding of pipelines as described in claim 7, characterized in that, In step S6, if the value exceeds the set range, the opening of the fluid proportional valve of the positive pressure delivery unit and the negative pressure return unit is adjusted, including the following adjustment methods: When W is less than the preset lower limit, increase the conveying airflow of the positive pressure conveying unit or decrease the recovery negative pressure of the negative pressure return unit; when W is greater than the preset upper limit, decrease the conveying airflow of the positive pressure conveying unit or increase the recovery negative pressure of the negative pressure return unit. When H is less than the preset lower limit, the flux input of the positive pressure conveying unit is increased; when H is greater than the preset upper limit, the recovery of the negative pressure return unit is enhanced or the flux input of the positive pressure conveying unit is reduced. When P exceeds the preset range, adjust the opening of the fluid proportional control valve of the positive pressure delivery unit and the negative pressure return unit to restore the pipeline pressure to the reference range.

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