Process equipment and welding process for weaving submerged arc welding of saddle-shaped welds using small diameter wires in a 3G position.

Abstract

This invention belongs to the field of high-temperature gas furnace manufacturing technology and provides process equipment and welding processes for weaving submerged arc welding of saddle-shaped welds using small diameter wires in a 3G position. [Solution] By utilizing the design of welding robots and welding processes, and while meeting standards and design specifications, and with the premise of significantly improving welding efficiency, the conventional submerged arc welding method has the problem of not being able to form the weld area, and a weaving submerged arc welding process using a small diameter wire can be adopted to improve welding efficiency.

Description

Technical Field

[0001] The present invention belongs to the technical field of high-temperature gas furnace manufacturing. Specifically, it relates to a process equipment and welding process for weaving and submerged arc welding with a small-diameter wire of a narrow groove with continuously variable angles in the 3G position of the large-sized saddle-shaped welded joint between the high-temperature gas duct and the cylinder assembly of the steam generator of a high-temperature gas furnace.

Background Art

[0002] A high-temperature gas furnace refers to a nuclear reactor technology with high-temperature characteristics that uses gas for core cooling. It uses graphite as a moderator and helium as a coolant, and realizes power generation through the conversion of atomic energy - thermal energy - mechanical energy - electrical energy. The high-temperature gas furnace, an advanced fourth-generation nuclear power reactor technology, has extremely high safety, so much so that it is called a "foolproof nuclear reactor". Even in the case of a serious accident where all cooling capabilities are lost and there is no external intervention, the nuclear reactor can still maintain a safe state and a core meltdown accident will not occur. Due to the special design of the fuel element, it can withstand high temperatures and has little residual heat, so it can remove the core heat only by natural heat dissipation. The high-temperature gas furnace has high thermal efficiency because the gaseous working fluid accumulates more heat and is converted into electrical energy more efficiently. By adjusting the output of the nuclear reactor, it can meet different power demands so that it can respond quickly to changes required by the load. Because the high-temperature gas furnace has a high outlet temperature, it can meet the demand for most heat sources in fields such as ethanol purification, petrochemicals, and hydrogen production.

[0003] In the main equipment and pressure vessels of nuclear power plants, the welds connecting cylinders and branch pipes have a saddle-like shape and are therefore called "saddle" welds. There are mainly two structural designs for saddle welds in conventional Chinese and overseas nuclear power plants and ordinary pressure vessels. One is a "pseudo-saddle" structure, in which the groove bottom is flat, the welding position is 1G, and the structure itself has no slope, so gravity has little effect on the shaping of the weld, making welding easy. However, it requires a large dimensional margin during procurement and later removal by machining, so procurement costs are considerably higher, and the subsequent machining process wastes a lot of resources, and this problem becomes more pronounced as the saddle size increases. Another structural form is the "true saddle" weld, where the groove bottom is a saddle surface with a certain incline. While this offers little room for machining, the saddle dimension typically does not exceed 40 mm, and the maximum allowable incline for upward and downward welding does not exceed 10°, remaining within the range of a downward position. Although gravity affects the metal in the molten pool during the welding process, it can still meet the requirements, albeit with differences in shaping and performance. In a "true saddle" structure, as the saddle dimension increases (the incline increases), the influence of gravity on the flow of metal in the molten pool increases during the welding process. When it exceeds a certain level (the incline exceeds 15°), the welding position changes from a downward position to an upright position. The molten iron in the molten pool is excessively affected by gravity to the point where it exceeds the surface tension of the molten pool itself, causing the molten iron to escape to the surroundings, resulting in poor shaping of the weld and affecting the weld quality.

[0004] In the structure of the high-temperature gas furnace product, the nozzle flange of the high-temperature gas duct (branch pipe) of the SG needs to be welded to the upper cylinder. The wall thickness of the SG cylinder is 205 mm, the groove bottom is a continuous saddle shape (see Figure 4 for a schematic diagram of the welding trajectory), the welding trajectory is 3G (downward) → 1G → 3G (upward) → 1G → 3G (downward) → 1G → 3G (upward) → 1G, the projection of the eight different trajectory segments on the circumference is eight unevenly divided circumferential regions, the spatial position and inclination of the welding gun change in real time, the maximum inclination difference is approximately 36° (the maximum angle for 3G upward is 18°, and the maximum angle for 3G downward is -18°), and the height difference (saddle dimension) is a maximum of approximately 380 mm. The saddle welds on the nozzle flanges of the high-temperature gas ducts of the upper cylinders are thick, with a groove depth of 260 mm in the circumferential direction of the cylinder. Approximately 1500 kg of welding rods are consumed to weld the nozzle flanges of the high-temperature gas ducts of one steam generator (SG). While the dimensions of the branch pipes in the high-temperature gas reactor RPV are the same as those of the SG branch pipes, the outer diameter and thickness of the cylinders are larger (6180 mm and 240 mm, respectively), and the saddle dimension is approximately 260 mm. Currently, the only practical example of a true saddle weld structure with such a large saddle dimension is a model project in a high-temperature gas reactor. In that project, the cylinder thickness is 180 mm, the difference in saddle height between the branch pipes is smaller, and an arc welding process with welding rods is employed. Differences in the skills of the welders are risk factors for quality control. Furthermore, the groove depth is large, and the utilization rate of welding rods is not high, resulting in approximately 1500 kg of welding rods being consumed to weld the nozzle flanges of the high-temperature gas ducts of one steam generator. While it is possible to complete the welding of the area using an arc welding process with welding rods, there are no advantages whatsoever in terms of welding quality or efficiency.

[0005] While some companies are attempting to implement automated TIG welding, technical deficiencies and limitations in the process itself mean that automated TIG welding cannot guarantee weld quality in -18° downward segments (the weld is in a downward welding position, and the upper weld metal is already covered by liquid metal before it is fully molten, resulting in shallow penetration depth. In the case of multi-layer welding, the interlayers do not achieve a complete metallurgical joint, making defects such as insufficient interlayer fusion more likely), posing a significant quality risk to product manufacturing. [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] The present invention was made to overcome the above-mentioned drawbacks of the prior art, and aims to provide a process equipment and method for weaving submerged arc welding of saddle-shaped welds using a small-diameter wire in a 3G position, thereby solving the problems present in the prior art. [Means for solving the problem]

[0007] The technical solutions employed by this invention to solve the technical problems are as follows: Process equipment for weaving submerged arc welding of saddle-shaped welds using a small diameter wire in a 3G position, It includes a steam generator, a welding robot, an operating platform, a lifting device, an external support device, an internal support device, and a heating assembly, the steam generator including a high-temperature gas duct and a cylinder assembly, The external support device fixes the high-temperature gas duct and cylinder assembly, The operating platform is provided above the welding area of ​​the high-temperature gas duct and cylinder assembly. The welding robot and lifting device are provided on one side of the high-temperature gas duct and cylinder assembly. The internal support device is provided within the high-temperature gas duct and cylinder assembly and is in contact with the inner wall surface of the high-temperature gas duct and cylinder assembly. The heating assembly is connected to the internal support device, and the heating assembly has a heating end that contacts the inner wall surface of the high-temperature gas duct and cylinder assembly.

[0008] Preferably, the welding robot includes a robot support, a robot base, a multi-axis movable mechanism, a multi-axis welding arm, and a welding gun, wherein the robot base is provided on the robot support, the multi-axis movable mechanism is provided on the robot base, the multi-axis welding arm is connected to the Z-axis movable end of the multi-axis movable mechanism, and the welding gun is connected to the Z-axis movable end of the multi-axis welding arm.

[0009] Preferably, the heating assembly includes an electric heating device and a plurality of heating plates, the electric heating device being electrically connected to the heating plates, the heating plates forming the heating end of the heating assembly, the heating plates being connected to the internal support device, and the heating plates being provided with saddle-shaped end faces that contact the inner wall surface of the high-temperature gas duct and cylinder assembly.

[0010] The present invention further, Step S1 involves fixing the high-temperature gas duct and cylinder assembly to the external support device, installing the welding robot and lifting device on the external support device side, and installing the internal support device and heating assembly inside the high-temperature gas duct and cylinder assembly. Step S2 involves turning on the heating assembly to preheat the high-temperature gas duct and cylinder assembly, Step S3 involves welding the weld groove between the high-temperature gas duct and the cylinder assembly, Step s31 involves first performing backing welding on the weld groove, then filling welding, and finally performing cover welding to form a cover weld bead. Step s32 involves performing temper welding on a coated weld bead to form a temper weld bead, Step S4 involves post-heating the high-temperature gas duct and cylinder assembly, Step S5 involves performing heat treatment on the high-temperature gas duct and cylinder assembly, Step S6 involves removing the internal support device within the high-temperature gas duct and cylinder assembly, The step includes step S7, in which non-destructive testing is performed on the high-temperature gas duct and cylinder assembly. This invention provides a welding process for welding saddle-shaped welds of high-temperature gas ducts and cylinder assemblies, employing a process equipment for weaving submerged arc welding of small diameter wires in a 3G position for the saddle-shaped welds described above.

[0011] Preferably, in step S1, the welding surface of the weld groove between the high-temperature gas duct and the cylinder assembly and the area within a minimum range of 50 mm nearby are cleaned so that the groove surface can meet the cleanliness requirements.

[0012] Preferably, in step S2, the preheating temperature range is 175 to 250°C, and the preheating time is 2 hours or more. In step S3, during the welding process, the temperature between the weld beads of the high-temperature gas duct and cylinder assembly is monitored to ensure it does not exceed 250°C. If the temperature of the workpiece rises due to the heat input during welding, the temperature of the area to be welded is allowed to cool naturally in the air to between 150°C and 250°C before continuing welding. The recommended temperature difference is 50°C or less. When performing shielded welding, the heating assembly ensures that the temperature of the area to be welded is between 210°C and 250°C. In step S4, after welding is interrupted or completed, post-heating should be performed on the welded area, with the post-heating temperature limited to 250-400°C and the post-heating time being 4 hours or more.

[0013] Preferably, in step S3, verification coordinate points are set before welding, the number of welding coordinate points is 32 or more, forward welding and backward welding can share welding coordinate points in the intermediate region, and independent welding coordinate points must be set in the arc start region and arc end region.

[0014] Preferably, in step s31, the weld groove is filled with fill welding, and the weld area is limited to be flush with the edge of the groove or up to 2 mm lower than the surface of the groove, and then the cover weld bead and tempered weld bead are welded. In steps s31 and s32, the number of weld beads in the covered weld bead is two or more, the number of weld beads in the tempered weld bead is one or more, one end of the covered weld bead covers the surface of the base material, the weld bead of the tempered weld bead overlaps with the covered weld bead and is located at 1 / 3 of the width of the covered weld bead.

[0015] Preferably, in step S3, the weld groove is a saddle-shaped narrow groove with a locking groove, the groove width at the bottom is 22 mm, the angle of the groove surface is 2°, and the minimum thickness of the backing plate in the locking groove is 6 mm. Backing and filling welds of the weld groove are multi-layer, multi-pass welds. The welding direction is changed after each layer of welding, and the change in groove width is monitored in real time. For areas with low cumulative thickness, single-stage thickness repair welding is performed for each area. The number of repair layers is determined based on actual measurement results. After repair welding, it is necessary to reduce the difference in groove width in each area, with a target difference of 3 mm or less. After completion, the remaining grooves are filled.

[0016] Preferably, in step S7, the non-destructive testing items include a visual inspection of the surface of the weld, a dimensional inspection of the weld, a magnetic particle inspection of the surface of the weld, an ultrasonic inspection of the weld, and a radiographic inspection of the weld. [Effects of the Invention]

[0017] The present invention has the following beneficial effects compared to the prior art. The process equipment and welding process adopted in this application are used for welding saddle-shaped welds of high-temperature gas ducts and cylinder assemblies, and can meet standards and design specifications, significantly improve welding efficiency, solve the problem of the weld not being able to form in conventional submerged arc welding, and improve welding efficiency.

[0018] The following briefly introduces the drawings to be used in the description of the embodiments in order to more clearly explain the technical solutions of the embodiments of the present invention. Needless to say, in the following description, the drawings are some embodiments of the present invention, and those skilled in the art can also obtain other drawings based on these drawings without creative efforts.

Brief Description of the Drawings

[0019] [Figure 1] It is a schematic diagram of the process equipment of the present invention. [Figure 2] It is a schematic diagram of the heating assembly of the present invention. [Figure 3] It is a schematic diagram of the distribution of the weld beads of the present invention. [Figure 4] It is a schematic diagram of the welding posture of the welded part of the present invention. [Figure 5] It is a schematic diagram of the position of the arc start point of the welded part of the present invention. [Figure 6] It is a schematic diagram of the process flow of the present invention.

Modes for Carrying Out the Invention

[0020] The present invention will be described in detail below with reference to the drawings and specific embodiments so that the above objects, features, and advantages of the present invention can be more clearly understood. It should be noted that, unless there is a contradiction, the embodiments of the present application and the features related to the embodiments can be combined with each other. In the following description, many details are described in order to fully understand the present invention, but the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments that can be obtained by those skilled in the art based on the embodiments of the present invention without creative efforts all belong to the protection scope of the present invention.

[0021] Unless otherwise defined, all technical and scientific terms used herein have their ordinary meanings as understood by those skilled in the art. Terms used in this specification are for the purpose of describing specific embodiments and are not intended to limit the invention.

[0022] (Examples) Referring to Figures 1 to 6, a process apparatus for weaving submerged arc welding of a saddle-shaped weld using a small diameter wire in a 3G position includes a welding robot 1, an operating platform 2, a lifting device 3, an external support device 4, an internal support device 5, and a heating assembly 6. The external support device 4 secures the high-temperature gas duct 7 and cylinder assembly of the steam generator. The operating platform 2 is located above the welding area of ​​the high-temperature gas duct 7 and the cylinder assembly. The welding robot 1 and the lifting device 3 are installed on one side of the high-temperature gas duct and cylinder assembly. The internal support device 5 is provided inside the high-temperature gas duct and cylinder assembly and is in contact with the inner wall surface of the high-temperature gas duct and cylinder assembly. The heating assembly 6 is connected to the internal support device 5, and the heating assembly 6 has a heating end that contacts the inner wall surface of the high-temperature gas duct and cylinder assembly.

[0023] The operator enters the operating platform 2 using the lifting device 3 and operates the welding robot 1 to perform welding.

[0024] Specifically, the welding robot 1 includes a robot support stand, a robot base, a multi-axis movable mechanism, a multi-axis welding arm, and a welding gun. The robot base is mounted on the robot support stand, the multi-axis movable mechanism is mounted on the robot base, the multi-axis welding arm is connected to the Z-axis movable end of the multi-axis movable mechanism, and the welding gun is connected to the Z-axis movable end of the multi-axis welding arm. The welding gun segment of this invention employs a flexible flux transport tube to enable arbitrary adjustment of the position and height of flux dripping, and is suitable for transporting flux during the welding process of both side and intermediate weld beads. The welding power supply is a QINEO NEXT617 Premium power supply from CLOOS, which has two modes: high-speed pulse mode (constant pressure / constant speed wire feeding) and deep penetration welding mode (constant current / variable speed wire feeding).

[0025] In this embodiment, a thin wire with a diameter of φ1.6 is used as the electrode and filler material, thereby concentrating the arc energy and reducing the effect of gravity on the molten iron in the molten pool. In submerged arc welding using thin wire, a stable voltage is required to ensure wire melting and uniform welding quality during the welding process. Therefore, the external characteristics of the power supply for submerged arc welding using thin wire are designed as constant voltage characteristics (high-speed pulse mode). Such external characteristics ensure that even if transient changes in the load state occur during the welding process (such as short-circuit transitions, particle transitions, and jet transitions of molten droplets), the power supply maintains a stable output voltage, ensuring that the welding process is carried out stably. The pulse phase is controlled by the voltage and is less susceptible to external factors such as changes in the protrusion length. The phase of the reference current is controlled by the current, and the arc can still be maintained even with a small current. Through effective internal control, voltage control of the pulse phase can guarantee arc stability. Because the arc direction is stable and the pressure is high, very high welding speeds can be achieved.

[0026] Furthermore, the addition of pulse mode further improves the arc's penetration characteristics, allowing for a larger depth-to-width ratio of the molten pool. In this case, the surface tension of the molten pool overcomes the effect of gravity, limiting the flow of the molten pool. In addition, in pulsed submerged arc welding, the pulses agitate the molten pool during welding, resulting in a more beautifully formed weld, a more uniform internal metal structure, and a metal structure that is closer to the base metal.

[0027] The heating assembly 6 of this embodiment includes an electric heating device and a plurality of heating plates, the electric heating device being electrically connected to the heating plates, the heating plates forming the heating end of the heating assembly 6, the heating plates being connected to an internal support device 5, and the heating plates being provided with saddle-shaped end faces that contact the inner wall surface of the high-temperature gas duct and cylinder assembly.

[0028] The present invention further, Step S1 involves fixing the high-temperature gas duct and cylinder assembly to the external support device 4, installing the welding robot 1 and lifting device 3 on the side of the external support device 4, and installing the internal support device 5 and heating assembly 6 inside the high-temperature gas duct and cylinder assembly. Step S2 involves turning on the heating assembly 6 to preheat the high-temperature gas duct and cylinder assembly, Step S3 involves welding a weld groove between a high-temperature gas duct and a cylinder assembly, Step s31 involves first performing backing welding on the weld groove, then filling welding, and finally performing cover welding to form a cover weld bead. Step s32 involves performing temper welding on a coated weld bead to form a temper weld bead, Step S4 involves post-heating the high-temperature gas duct and cylinder assembly, Step S5 involves performing heat treatment on the high-temperature gas duct and cylinder assembly, Step S6 involves removing the internal support device 5 within the high-temperature gas duct and cylinder assembly, The step includes step S7, in which non-destructive testing is performed on the high-temperature gas duct and cylinder assembly. This invention provides a welding process for welding saddle-shaped welds of high-temperature gas ducts and cylinder assemblies, employing a process equipment for weaving submerged arc welding of small diameter wires in a 3G position for the saddle-shaped welds described above.

[0029] Specifically, in step S1, the welding surface of the weld groove between the high-temperature gas duct and the cylinder assembly, and the area within a minimum range of 50 mm in the vicinity, are cleaned to ensure that the groove surface meets the cleanliness requirements.

[0030] Specifically, in step S2, the preheating temperature range is 175-250°C, and the preheating time is 2 hours or more. In step S3, during the welding process, the high-temperature gas duct and cylinder assembly Between welding passes The temperature is monitored to ensure it does not exceed 250°C. If the temperature of the workpiece rises due to the heat input during welding, the temperature of the welding area is allowed to cool naturally in the air to between 150°C and 250°C before continuing welding. The recommended temperature difference is 50°C or less. When performing shielded welding, the heating assembly 6 ensures that the temperature of the welding area is between 210°C and 250°C. In step S4, after welding is interrupted or completed, the weld area is post-heated. This should be done, and the post-heating temperature should be limited to 250-400°C, with a post-heating time of 4 hours or more. be.

[0031] Specifically, in step S3, verification coordinate points are set before welding, the number of welding coordinate points is 32 or more, forward welding and backward welding can share welding coordinate points in the intermediate region, and independent welding coordinate points must be set in the arc start region and arc end region.

[0032] Specifically, in step s31, the weld groove is filled with fill welding, and the weld area is limited to be flush with the edge of the groove or up to 2 mm lower than the surface of the groove, and then the cover weld bead and tempered weld bead are welded. In steps s31 and s32, the number of weld beads in the covered weld bead is two or more, the number of weld beads in the tempered weld bead is one or more, one end of the covered weld bead covers the surface of the base metal, the weld bead of the tempered weld bead overlaps with the covered weld bead and is located at 1 / 3 of the width of the covered weld bead.

[0033] In this embodiment, as shown in Figure 3, the weld beads of the covered weld bead are A, B, and C, respectively, arranged from left to right. The electrode is adjusted to an appropriate position depending on the degree to which it is flush with the surface of the base material of the already completed weld, ensuring that the weld bead of the covered weld bead covers about 5 mm of the surface of the groove base material. Furthermore, based on the actual width of the groove and the degree of filling of the weld at position B, it is determined whether or not to weld B, and if the recess amount at position B exceeds 1 mm, it is necessary to weld B.

[0034] The tempered weld beads are D and E, respectively, which are formed sequentially from left to right. D and E must overlap at approximately 1 / 3 of the width of A and C, and this must be calculated based on the sum of the actual widths of A, B, and C. If the groove is narrow, after completing position D, E may be skipped if the overlapping dimensions of weld bead D with weld beads A and C meet the requirements.

[0035] The base material in this embodiment is ASME SA508 grade 3CL.1 forged material, which has excellent overall mechanical properties and is therefore widely used in the manufacture of nuclear power plant equipment.

[0036] Specifically, in step S3, the weld groove is a saddle-shaped narrow groove with a locking groove, the groove width at the bottom is 22 mm, the angle of the groove surface is 2°, and the minimum thickness of the backing plate in the locking groove is 6 mm. Backing and filling welds of the weld groove are multi-pass welds. After each pass of welding is completed, the flux is cleaned and the weld is inspected to confirm the quality of the weld before proceeding to the next pass. For each pass of welding, the welding position changes in real time during the continuous welding process. As shown in Figure 4, there are a total of eight stages centered around the high and low points of the saddle. The projection of the eight stages around the circumference is an unevenly divided circumferential region including 3G downward → 1G → 3G upward → 1G → 3G downward → 1G → 3G upward → 1G. When the molten iron in the molten pool is located in different regions, the effect of gravity on it differs, resulting in significant differences in the weld formation in different regions. In the downward position, gravity is perpendicular to the welding direction, and its effect on the weld formation is small. During 3G upward welding, gravity acts against the welding direction, and is opposed to the arc force, the supporting force of the previously welded metal, and the surface tension of the weld itself. This results in significant compression of the molten iron in the molten pool, ultimately forming a narrow and thick weld. During 3G downward welding, gravity is aligned with the welding direction, and is opposed to the arc force and the supporting force of the previously welded metal. The only opposing force is the surface tension of the weld itself, allowing the molten iron in the molten pool to expand to some extent, resulting in a wide and thin weld. Consequently, the thickness of single-layer welds in different regions does not coincide (especially in 3G upward and 3G downward welding), which directly affects the setting of the weld lift for the next layer. Furthermore, as the groove is filled, this difference becomes increasingly apparent, and in extreme cases, due to differences in the cumulative thickness of the weld (in the groove structural design adopted in this project, the groove width is the same around the entire circumference at the same depth position), the groove width in the aforementioned different regions of the next weld bead differs so greatly that it exceeds the maximum allowable range that the parameters can handle, resulting in insufficient fusion.

[0037] Therefore, the welding direction is changed with each layer welded, forcing a swap of the forming characteristics of the welds in the eight regions on the circumference. When welding the next layer, the 3G downward region of the previous layer becomes a 3G upward region, and the 3G upward region of the previous layer becomes a 3G downward region, while the 1G position remains unchanged. In this way, it is ensured that the cumulative thickness of every two welds matches (approximately 7 mm) across the entire circumference. Furthermore, during 3G upward welding, because the weld is narrow and thick, the amount of overlap between weld beads is less within the groove, resulting in relatively poor interlayer fusion and a greater likelihood of defects due to insufficient fusion. The design of the process according to the above invention effectively improves the problem of the forming deteriorating due to the continuous accumulation of welds during welding of the 3G upward region by inserting one 3G downward weld in the layer following the original 3G upward region.

[0038] Simultaneously, the change in groove width is monitored in real time, and single-stage thickness repair welding is performed on areas with low cumulative thickness. The number of repair layers is determined based on the actual measurement results. After repair welding, it is necessary to reduce the difference in groove width in each area, with a target difference of 3 mm or less. After completion, the remaining grooves are filled.

[0039] The forming characteristics of the weld in the 3G upward region and the 3G downward region differ; the 3G upward region is narrow and thick, while the 3G downward region is wide and thin. Regarding the control of arc start and arc end, in this project, the arc start point and arc end point are set in the 3G downward region according to the forming characteristics of the weld. Four regions are provided and arc start is performed symmetrically, as shown in Figure 5, these are arc start point 1, arc start point 2, arc start point 3, and arc start point 4. By changing the arc start position after each layer of welding and shifting the joint region by at least 50 mm, it is possible to avoid the concentration of deformation that occurs when arc start and arc end are performed consecutively at the same position. The advantage is that the molten iron in the molten pool spreads effectively in the 3G downward region, the overlapping transition region is smoother, the molten iron can freely fill the gap region, and insufficient fusion is less likely to occur.

[0040] Specifically, in step S7, the non-destructive testing items include visual inspection of the weld surface, dimensional inspection of the weld, magnetic particle inspection of the weld surface, ultrasonic inspection of the weld, and radiographic inspection of the weld.

[0041] As can be seen from the above, the welding robot 1 of this application is a multi-axis movable structure that controls the welding weaving parameters, enabling high-speed, high-frequency weaving welding, and moreover, the weaving trajectory is more accurate. By introducing weaving, the width of each weld is no longer limited by the specifications of the filler material, enabling free control, reducing the number of weld beads in each layer, improving welding efficiency, and reducing the risk of insufficient fusion between weld beads. The molten pool morphology can be made more uniform, resulting in a smoother surface for the weld, improved quality, and reduced subsequent polishing work. During the weaving welding process, the arc also has the effect of stirring the molten pool, which helps to expel gas and reduce the generation of pores. Furthermore, when employing pulsed submerged arc welding technology with a small diameter wire, the pulsed arc has the effect of stirring the molten pool, resulting in a more beautifully shaped weld, a more uniform internal metal structure, and a metal structure that is closer to the base material. The energy of the pulsed arc is more concentrated, and in the same situation, the amount of heat input can be greatly reduced, the crystal grain can be refined, and the performance of the weld can be improved. Furthermore, the concentrated arc energy allows for better arc penetration characteristics, resulting in faster melting of the base metal and filler material in the arc-covered area, improving welding efficiency and increasing welding speed, thus significantly improving production efficiency. In addition, the good arc penetration characteristics allow for good edge fusion without setting a weaving stop time when setting parameters, and the problem of uncontrolled outflow of the molten pool causing molding defects is effectively mitigated by confining the molten iron in the molten pool to the area pointed to by the arc. Moreover, the pulse energy of the small diameter wire is more concentrated, reducing the effect of gravity on the molten pool, and ensuring that the molten area has enough heat to separate gas and molten slag from the weld, perfectly resolving defects such as molding defects, porosity, and molten slag in the weld in structures with large angle changes, such as continuous upward and downward movements.

[0042] The above-described content is merely a preferred embodiment of the present invention and does not limit the present invention in any way. Therefore, any modifications, equivalent changes, or modifications made to the above embodiments based on the technical gist of the present invention, as long as they do not depart from the technical solution of the present invention, are all within the scope of the technical solution of the present invention. [Explanation of Symbols]

[0043] 1. Welding robot 2. Operating Platform 3. Lifting device 4 External support device 5 Internal support device 6. Heating Assembly 7. High-temperature gas duct

Claims

1. This welding process was used for welding saddle-shaped welds between high-temperature gas ducts and cylinder assemblies. hand, A process equipment for weaving submerged arc welding of saddle-shaped welds using a small diameter wire in a 3G position, It includes a steam generator, a welding robot, an operating platform, a lifting device, an external support device, an internal support device, and a heating assembly, the steam generator including a high-temperature gas duct and a cylinder assembly, The external support device fixes the high-temperature gas duct and the cylinder assembly, The operating platform is provided above the welding area of ​​the high-temperature gas duct and the cylinder assembly. The welding robot and lifting device are provided on one side of the high-temperature gas duct and the cylinder assembly. The internal support device is provided within the high-temperature gas duct and the cylinder assembly, and contacts the inner wall surface of the high-temperature gas duct and the cylinder assembly. The heating assembly is connected to the internal support device, the heating assembly has a heating end, the heating end contacts the high-temperature gas duct and the inner wall surface of the cylinder assembly, The welding robot includes a robot support stand, a robot base, a multi-axis movable mechanism, a multi-axis welding arm, and a welding gun, wherein the robot base is provided on the robot support stand, the multi-axis movable mechanism is provided on the robot base, the multi-axis welding arm is connected to the Z-axis movable end of the multi-axis movable mechanism, and the welding gun is connected to the Z-axis movable end of the multi-axis welding arm. The heating assembly includes an electric heating device and a plurality of heating plates, the electric heating device being electrically connected to the heating plates, the heating plates forming the heating end of the heating assembly, the heating plates being connected to the internal support device, and the heating plates being provided with saddle-shaped end faces that contact the high-temperature gas duct and the inner wall surface of the cylinder assembly, the process equipment includes Step S1 involves fixing the high-temperature gas duct and the cylinder assembly to the external support device, installing the welding robot and lifting device on the external support device side, and installing the internal support device and the heating assembly inside the high-temperature gas duct and the cylinder assembly. Step S2 is a step of turning on the heating assembly to preheat the high-temperature gas duct and the cylinder assembly, wherein the preheating temperature range is 175 to 250°C and the preheating time is 2 hours or more. Step S3 is to weld the weld groove between the high-temperature gas duct and the cylinder assembly, Step s31 involves first performing backing welding on the aforementioned weld groove, then filling welding, and finally performing coating welding to form a coating weld bead. The step s32 includes performing temper welding on the coated weld bead to form a temper weld bead, In step S3, during the welding process, the temperature between the welding paths of the high-temperature gas duct and the cylinder assembly is monitored to ensure it does not exceed 250°C. If the temperature of the workpiece rises due to the heat input during welding, the temperature of the welding area is allowed to cool naturally in the air to between 150°C and 250°C before continuing welding. The recommended temperature difference is 50°C or less. When performing shielded welding, the heating assembly ensures that the temperature of the welding area is between 210°C and 250°C. The aforementioned weld groove is a saddle-shaped narrow groove with a locking groove, the groove width at the bottom is 22 mm, the groove surface angle is 2°, and the minimum thickness of the backing plate in the locking groove is 6 mm. The backing and filling welds of the aforementioned weld grooves are multi-layer multi-pass welds. The welding direction is changed after each layer of welding, and the change in groove width is monitored in real time. For areas with low cumulative thickness, single-stage thickness repair welding is performed for each area. The number of repair layers is determined based on actual measurement results. After repair welding, it is necessary to reduce the difference in groove width in each area, with a target difference of 3 mm or less. After completion, the remaining grooves are filled. In step s31, the weld groove is filled with fill welding, and the weld area is limited to be flush with the edge of the groove or up to 2 mm lower than the surface of the groove, and then the cover weld bead and tempered weld bead are welded. In steps s31 and s32, the number of weld beads in the covered weld bead is two or more, the number of weld beads in the tempered weld bead is one or more, one end of the covered weld bead covers the surface of the base material, the weld bead of the tempered weld bead overlaps with the covered weld bead, and of the two ends of the covered weld bead, it is located at a point 1 / 3 from the end that does not overlap with the weld bead of the tempered weld bead. Furthermore, step S4 is a step of performing post-heating on the high-temperature gas duct and the cylinder assembly, wherein post-heating should be performed on the welded area after welding has been interrupted or completed, the post-heating temperature is limited to 250 to 400°C, and the post-heating time is 4 hours or more. Step S5 involves performing heat treatment on the high-temperature gas duct and the cylinder assembly, Step S6 involves removing the high-temperature gas duct and the internal support device within the cylinder assembly, The step includes performing a non-destructive test on the high-temperature gas duct and the cylinder assembly, A welding process characterized by the following:

2. In step S1, the welding surface of the weld groove between the high-temperature gas duct and the cylinder assembly and the area within a minimum range of 50 mm nearby are cleaned to ensure that the groove surface meets the cleanliness requirements. A welding process used for welding a saddle-shaped welded joint of a high-temperature gas duct and cylinder assembly as described in feature 1.

3. In step S7, the non-destructive testing items include visual inspection of the weld surface, dimensional inspection of the weld, magnetic particle inspection of the weld surface, ultrasonic inspection of the weld, and radiographic inspection of the weld. A welding process used for welding a saddle-shaped welded joint of a high-temperature gas duct and cylinder assembly as described in feature 1.

Images