A tooling and welding process for 3G position fine wire swing submerged arc welding of saddle-shaped weld

Abstract

The present invention belongs to the technical field of high-temperature gas-cooled reactor equipment manufacturing, and discloses a tooling and welding process for 3G position fine-wire swing submerged arc welding of a saddle-shaped weld. The present invention utilizes the design of a welding robot and a welding process, and can solve the problem that a traditional submerged arc welding weld cannot be formed, thereby improving welding efficiency, while meeting standards and design specifications and greatly improving welding efficiency.

Description

Technical Field

[0001] The present invention belongs to the technical field of high temperature gas-cooled reactor equipment manufacturing, and specifically relates to a tooling and welding process for continuous variable angle narrow gap fine wire swing submerged arc welding of a super large saddle amount saddle-shaped weld 3G position of a hot gas duct and a cylinder assembly of a high temperature gas-cooled reactor steam generator. Background Art

[0002] High temperature gas-cooled reactor refers to a nuclear reactor technology with high temperature characteristics and using gas for core cooling. It uses graphite as a moderator and helium as a coolant to generate electricity through the conversion of nuclear energy-thermal energy-mechanical energy-electrical energy. As an advanced fourth-generation nuclear power reactor technology, the high temperature gas-cooled reactor has extremely high safety and is called a "fool reactor". Even if all cooling capacity is lost and a serious accident is faced, the reactor can remain safe without any external intervention and there will be no core meltdown accident. The special design of the fuel elements enables it to withstand high temperatures and has little residual heat, so the core heat can be taken away by natural heat dissipation alone. The high temperature gas-cooled reactor has a high thermal efficiency because the gas working fluid can accommodate more heat and thus be converted into electricity more efficiently. It can respond to changes in load demand more quickly and meet different power needs by adjusting the power output of the reactor. The high temperature gas-cooled reactor has a high outlet temperature and can meet most of the heat source needs in the fields of ethanol purification, petrochemicals, and hydrogen production.

[0003] In the main equipment of the nuclear island and the pressure vessel, the intersecting weld between the cylinder and the nozzle is called a "saddle-shaped" weld because of its shape similar to a saddle. There are two main design structures for saddle-shaped welds of existing nuclear power equipment and conventional pressure vessels at home and abroad. One is the "false saddle" structure, the bottom of the groove is flat, the welding position is 1G, the welding difficulty of this structure itself is low, because there is no slope, gravity has almost no effect on the weld formation, but it needs to reserve a large amount of size margin in the procurement stage, and then remove it by machining, so its procurement cost is higher, and the waste of machining resources in the later process is high. The larger the saddle amount, the more prominent the above problem; the other is the "real saddle" structure, the bottom of the groove is a saddle surface, with a certain slope, and less reserved machining margin, but usually the saddle amount does not exceed 40mm, the upper and lower limit slopes do not exceed 10°, and it is still within the range of flat welding. During the welding process, gravity has an effect on the molten pool metal. Although there are differences in forming and performance, it can still meet the requirements. For the "real saddle" structure, as the saddle amount increases (the slope increases), the flow of the molten pool metal is increasingly affected by gravity during the welding process. When it exceeds a certain degree (slope ≥ 15°), the welding position has changed from flat welding to vertical welding. The molten iron in the molten pool is too affected by gravity, exceeding the surface tension of the molten pool itself, causing the molten iron to escape to the surroundings, resulting in poor weld formation and affecting the welding quality.

[0004] In the product structure of high temperature gas-cooled reactor, the nozzle flange of SG hot gas duct (pipe) needs to be welded with the upper cylinder, where the wall thickness of SG cylinder is 205mm, and the bottom surface of the groove is a continuous saddle shape (welding trajectory is shown in the figure). Figure 4 ), the welding trajectory is 3G (downward) → 1G → 3G (upward) → 1G → 3G (downward) → 1G → 3G (upward) → 1G, and the 8 different trajectory segments are projected on the arc as 8 non-equal arc areas. The spatial position and slope of the welding gun change in real time, and the maximum slope difference is about 36° (the maximum angle of 3G upward is 18°, and the maximum angle of 3G downward is -18°), and the maximum height difference (saddle amount) is about 380mm. The thickness of the saddle weld between the upper cylinder and the hot gas duct nozzle flange is large, and the groove depth of the cylinder circumference is 260mm. The welding of the hot gas duct nozzle flange of one SG requires about 1500Kg of welding. The size of the pipe on the high temperature gas-cooled reactor RPV is consistent with that of the SG, but the outer diameter and thickness of the cylinder are larger (6180mm and 240mm respectively), and the saddle amount is about 260mm. For this type of real saddle welding structure with a large amount of saddles, the mature case that can be referenced is the high-temperature gas-cooled reactor demonstration project. The barrel thickness of this project is 180mm, and the saddle drop of the pipe is smaller. It uses arc welding technology, and factors such as differences in welder skills pose risks to quality control. At the same time, due to the large groove depth, the utilization rate of welding rods is not high. The hot gas duct nozzle flange welding of a single steam generator requires nearly 1,500 kg of welding rods. The arc welding process can only complete the welding of this weld, but it has no advantages in welding quality and efficiency.

[0005] Some companies have tried to use automatic TIG welding, but it has technical defects. Due to the limitations of the process method itself, the welding quality of automatic TIG welding cannot be guaranteed for the downhill section of -18° (when welding in the downhill welding position, the upper weld metal has been covered by liquid metal before it is fully melted, and the penetration depth is shallow. When welding multiple layers, the layers do not achieve complete metallurgical bonding, which easily leads to defects such as lack of fusion between layers). There are huge quality risks in product manufacturing. Summary of the invention

[0006] In order to overcome the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a tool and method for fine wire swing submerged arc welding at the 3G position of a saddle weld, aiming to solve the problems existing in the prior art.

[0007] The technical solution adopted by the present invention to solve its technical problem is:

[0008] A tool for 3G position fine wire swing submerged arc welding of a saddle weld, comprising a steam generator, a welding robot, an operating platform, a lifting device, an external support device, an internal support device and a heating component, wherein the steam generator comprises a hot air conduit and a barrel component;

[0009] The external support device is used to fix the hot gas conduit and the barrel assembly;

[0010] The operating platform is arranged above the welding area of ​​the hot gas duct and the cylinder assembly;

[0011] The welding robot and the lifting device are arranged on one side of the hot gas duct and the cylinder assembly;

[0012] The internal support device is disposed in the hot air conduit and barrel assembly and contacts the inner wall surface of the hot air conduit and barrel assembly;

[0013] The heating component is connected to the internal supporting device, and the heating component has a heating end, and the heating end is in contact with the hot air conduit and the inner wall surface of the barrel component.

[0014] Preferably, the welding robot includes a robot support platform, a robot base, a multi-axial movable mechanism, a multi-axial welding arm and a welding gun, the robot base is arranged on the robot support platform, the multi-axial movable mechanism is arranged on the robot base, the multi-axial welding arm is connected to the Z-direction movable end of the multi-axial movable mechanism, and the welding gun is connected to the Z-direction movable end of the multi-axial welding arm.

[0015] Preferably, the heating assembly includes an electric heating device and a plurality of heating plates, the electric heating device is electrically connected to the heating plates, the heating plates form the heating end of the heating assembly, the heating plates are connected to the internal supporting device, and the heating plates are provided with a saddle-shaped end surface that contacts the hot air duct and the inner wall surface of the barrel assembly.

[0016] The present invention also includes a welding process for saddle-shaped welds of hot gas ducts and barrel components, using the above-mentioned saddle-shaped weld 3G position fine wire swing submerged arc welding tooling, comprising the following steps:

[0017] S1. Fix the hot air conduit and the barrel assembly to the external support device, place the welding robot and the lifting device on one side of the external support device, and install an internal support device and a heating assembly in the hot air conduit and the barrel assembly;

[0018] S2, turning on the heating component to preheat the hot air duct and the cylinder component;

[0019] S3, welding the welding groove between the hot gas conduit and the cylinder assembly:

[0020] s31. First, perform a base weld on the welding groove, then perform a filler weld, and finally perform a cap weld to form a cap weld bead;

[0021] s32, perform tempering weld at the cap weld and form a tempering weld bead;

[0022] S4, post-heating the hot gas duct and the barrel assembly;

[0023] S5. heat treating the hot gas duct and the cylinder assembly;

[0024] S6. Remove the internal support device in the hot gas duct and the cylinder assembly;

[0025] S7. Perform non-destructive testing on the hot gas duct and cylinder assembly.

[0026] Preferably, in step S1, the surface to be welded of the welding groove between the hot gas conduit 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 requirement.

[0027] Preferably, in step S2, the preheating temperature range is 175-250°C, and the preheating time is not less than 2 hours;

[0028] In step S3, the temperature between the hot gas duct and the barrel assembly is monitored during the welding process to ensure that it does not exceed 250°C. When the workpiece temperature rises due to the welding heat input, the welding area should be cooled naturally in the air until the temperature reaches between 150-250°C before continuing the welding. The recommended temperature difference is ≤50°C. When performing the cover weld, the heating assembly is used to ensure that the temperature of the welding area is between 210-250°C.

[0029] In step S4, after the welding is interrupted or completed, the welding area should be post-heated, the post-heating temperature is controlled at 250-400°C, and the post-heating time is not less than 4 hours.

[0030] Preferably, in step S3, verification coordinate points are established before welding, the number of welding coordinate points is not less than 32, forward welding and reverse welding can share the welding coordinate points in the middle area, and independent welding coordinate points need to be set for the arc starting and arc ending areas.

[0031] Preferably, in step s31, the welding groove is filled with a filling weld, and the filling weld area is controlled to be flush with or within 2 mm below the groove edge before welding the capping and tempering welds;

[0032] In steps s31 and s32, the number of the cover welds is more than two, the number of the tempering welds is more than one, one end of the cover weld covers the surface of the welding base material, and the tempering weld overlaps the cover weld and is at 1 / 3 of the width of the cover weld.

[0033] Preferably, in step S3, the welding groove is a saddle-shaped narrow gap groove with a locking groove, the bottom groove width is 22 mm, the groove surface angle is 2°, and the minimum thickness of the pad at the locking groove is 6 mm;

[0034] The base weld and filling weld of the welding groove are multi-layer and multi-pass welds. The welding direction is changed after each layer is welded. At the same time, the change of groove width is monitored in real time. Single-stage thickness supplementary welding is carried out in different areas for areas with low cumulative thickness. The number of supplementary layers is determined according to the actual measurement results. After the supplementary welding, the difference in groove width of each area needs to be reduced. The target value of the difference is ≤3mm. After completion, the remaining grooves are filled.

[0035] Preferably, in step S7, the nondestructive testing items include visual inspection of the weld surface, weld size inspection, weld surface magnetic particle inspection, weld ultrasonic inspection and weld radiographic inspection.

[0036] Compared with the prior art, the beneficial effects of the present invention include:

[0037] The tooling and welding process adopted in this application are applied to the saddle-shaped welds of the hot gas duct and the cylinder assembly. On the premise of meeting the standards and design specifications and greatly improving the welding efficiency, it can solve the problem that the traditional submerged arc welding welds cannot be formed and improve the welding efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying any creative work.

[0039] Figure 1 It is a schematic diagram of the tooling of the present invention.

[0040] Figure 2 Schematic diagram of the heating component of the present invention.

[0041] Figure 3 It is a schematic diagram of the weld arrangement of the present invention.

[0042] Figure 4 It is a schematic diagram of the welding position of the weld of the present invention.

[0043] Figure 5 It is a schematic diagram of the arc starting point position of the weld of the present invention.

[0044] Figure 6 It is a schematic diagram of the process flow of the present invention.

[0045] in:

[0046] 1- welding robot, 2- operating platform, 3- lifting device, 4- external support device, 5- internal support device, 6- heating component, 7- hot air duct. DETAILED DESCRIPTION

[0047] In order to more clearly understand the above-mentioned objects, features and advantages of the present invention, the present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that, in the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other. In the following description, many specific details are set forth in order to fully understand the present invention, and the embodiments described are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the art without making creative work are within the scope of protection of the present invention.

[0048] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0049] Example:

[0050] See also Figure 1-Figure 6 , a tooling for fine wire swing submerged arc welding at position 3G of a saddle weld, comprising a welding robot 1, an operating platform 2, a lifting device 3, an external supporting device 4, an internal supporting device 5 and a heating component 6;

[0051] The external support device 4 is used to fix the hot gas conduit 7 and the cylinder assembly of the steam generator;

[0052] The operating platform 2 is arranged above the hot gas duct 7 and the welding area of ​​the cylinder assembly;

[0053] The welding robot 1 and the lifting device 3 are arranged on one side of the hot gas duct and the cylinder assembly;

[0054] The internal support device 5 is arranged in the hot gas conduit and the barrel assembly and contacts the inner wall surface of the hot gas conduit and the barrel assembly;

[0055] The heating component 6 is connected to the internal supporting device 5, and the heating component 6 has a heating end, and the heating end is in contact with the hot air conduit and the inner wall surface of the cylinder component.

[0056] The operator enters the operating platform 2 through the lifting device 3 and controls the welding robot 1 to perform welding.

[0057] Specifically, the welding robot 1 includes a robot support platform, a robot base, a multi-axial moving mechanism, a multi-axial welding arm and a welding gun. The robot base is arranged on the robot support platform, the multi-axial moving mechanism is arranged on the robot base, the multi-axial welding arm is connected to the Z-direction moving end of the multi-axial moving mechanism, and the welding gun is connected to the Z-direction moving end of the multi-axial welding arm. The welding gun section of the present application adopts a flexible flux delivery pipe to achieve arbitrary adjustment of the flux falling position and height, and can be applied to the flux delivery during the welding process of both sides and the middle weld. The welding power supply adopts CLOOS's QINEO NEXT617 Premium power supply, which has two modes: high-speed pulse mode (constant pressure and constant speed wire feeding) and deep melting welding mode (constant current and variable speed wire feeding).

[0058] In this embodiment, a φ1.6 thin wire is used as an electrode and filler metal to make the arc energy more concentrated and reduce the influence of gravity on the molten iron in the molten pool. For fine-wire submerged arc welding, since a stable voltage is required during the welding process to ensure the melting of the welding wire and the uniformity of the welding quality, the external characteristics of the fine-wire submerged arc welding power supply are designed as a constant voltage characteristic (high-speed pulse mode). This external characteristic can ensure that during the welding process, even if the load state changes instantaneously (such as short-circuit transition of the molten droplet, particle transition, jet transition, etc.), the power supply can maintain the stability of the output voltage, thereby maintaining the stability of the welding process. The pulse phase is controlled by voltage and is not easily affected by external factors, such as changes in dry extension. The reference current phase is controlled by current, and the arc can be maintained even at low current. Thanks to effective internal control, the voltage control of the pulse phase can ensure the stability of the arc. Due to the stable direction and strong pressure of the arc, a very high welding speed can be achieved.

[0059] At the same time, the addition of pulse mode further improves the arc penetration effect, and can obtain a larger molten pool depth-to-width ratio. At this time, the surface tension of the molten pool is greater than its own gravity, which limits the flow of the molten pool. At the same time, the pulsed submerged arc welding stirs the molten pool during welding, making the weld more beautiful, the internal metal structure more uniform, and the metallographic structure closer to the parent material.

[0060] The heating assembly 6 of this embodiment includes an electric heating device and a plurality of heating plates. The electric heating device is electrically connected to the heating plates. The heating plates form the heating end of the heating assembly 6. The heating plates are connected to the internal support device 5. The heating plates are provided with a saddle-shaped end surface that contacts the hot air duct and the inner wall surface of the cylinder assembly.

[0061] The present invention also includes a welding process for saddle-shaped welds of hot gas ducts and barrel components, using the above-mentioned saddle-shaped weld 3G position fine wire swing submerged arc welding tooling, comprising the following steps:

[0062] S1. Fix the hot air conduit and the barrel assembly to the external support device 4, place the welding robot 1 and the lifting device 3 on one side of the external support device 4, and install the internal support device 5 and the heating assembly 6 in the hot air conduit and the barrel assembly;

[0063] S2, turning on the heating component 6 to preheat the hot air conduit and the cylinder component;

[0064] S3. Weld the welding groove between the hot gas duct and the cylinder assembly:

[0065] s31. First, perform a base weld on the welding groove, then perform a filler weld, and finally perform a cap weld to form a cap weld bead;

[0066] s32. Perform tempering weld at the cover weld and form a tempering weld.

[0067] S4, post-heating the hot gas duct and the barrel assembly;

[0068] S5. heat treating the hot gas duct and the cylinder assembly;

[0069] S6, removing the internal support device 5 in the hot gas duct and the cylinder assembly;

[0070] S7. Perform non-destructive testing on the hot gas duct and cylinder assembly.

[0071] Specifically, in step S1, the to-be-welded surface of the welding groove between the hot 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 requirement.

[0072] Specifically, in step S2, the preheating temperature range is 175-250°C, and the preheating time is not less than 2 hours;

[0073] In step S3, the temperature between the hot gas conduit and the barrel assembly is monitored during the welding process to ensure that it does not exceed 250°C. When the workpiece temperature rises due to the welding heat input, the workpiece should be cooled naturally in the air until the temperature of the area to be welded reaches between 150-250°C before continuing welding. The recommended temperature difference is ≤50°C. When performing the cover weld, the heating assembly 6 is used to ensure that the temperature of the area to be welded is between 210-250°C.

[0074] In step S4, after the welding is interrupted or completed, the welding area should be post-heated, the post-heating temperature is controlled at 250-400°C, and the post-heating time is not less than 4 hours.

[0075] Specifically, in step S3, verification coordinate points are established before welding, and the number of welding coordinate points is not less than 32. Forward welding and reverse welding can share the welding coordinate points in the middle area. For the arc starting and arc ending areas, independent welding coordinate points need to be set.

[0076] Specifically, in step s31, the welding groove is filled with a filling weld, and the filling weld area is controlled to be flush with or within 2 mm below the groove edge before the capping and tempering welds are welded;

[0077] In steps s31 and s32, the number of the cap weld is more than two, the number of the tempering weld is more than one, one end of the cap weld covers the surface of the welding base material, and the tempering weld overlaps the cap weld and is at 1 / 3 of the width of the cap weld.

[0078] In this embodiment, according to Figure 3 As shown, the welds of the cover weld are A, B, and C set from left to right. According to the flushness of the completed weld and the surface of the base material, adjust the electrode to a suitable position to ensure that the weld of the cover weld covers the surface of the groove base material by about 5 mm. At the same time, according to the actual width of the groove and the fullness of the weld at position B, determine whether to weld B. If the concave amount at position B exceeds 1 mm, B needs to be welded.

[0079] The order of the tempering welds is D and E from left to right. D and E need to overlap at about 1 / 3 of the width of A and C, which needs to be calculated based on the actual total width of A, B and C. If the groove is narrow, after completing sequence D, if the overlap of weld D with welds A and C meets the size requirements, E does not need to be performed.

[0080] The parent material of this embodiment is an American Standard ASME grade SA508-3CL.1 forging. SA508-3CL.1 forging has excellent comprehensive mechanical properties and is widely used in the manufacture of nuclear power equipment.

[0081] Specifically, in step S3, the welding groove is a saddle-shaped narrow gap groove with a locking groove, the bottom groove width is 22 mm, the groove surface angle is 2°, and the minimum thickness of the pad at the locking groove is 6 mm;

[0082] The base weld and filler weld of the welding groove are multi-layer and multi-pass welds. After each weld, the flux is cleaned and the weld is inspected. After the weld forming quality is confirmed, the next weld is continued. For each weld, the welding position changes in real time during the continuous welding process, such as Figure 4As shown in the figure, there are 8 stages around the saddle high point and the saddle point, and the 8 stages are projected into 8 non-equal arc areas on the arc, including: 3G downward → 1G → 3G upward → 1G → 3G downward → 1G → 3G upward → 1G; when the molten iron in the molten pool is in different areas, it is affected by gravity differently, which makes the weld formation in different areas have great differences. In flat welding, gravity is perpendicular to the welding direction and has little effect on the weld formation; in 3G upward welding, gravity is opposite to the welding direction, gravity is opposite to the arc force, the supporting force of the first weld metal, and its own surface tension, the molten iron in the molten pool will be significantly compressed, and the weld will eventually be narrow and thick; in 3G downward welding, gravity is the same as the welding direction, gravity is the same as the arc force and the supporting force of the first weld metal, and the reverse force is only the surface tension of itself, the molten iron in the molten pool can be freely spread to a certain extent, and the weld is wide and thin. Therefore, the thickness of the single-layer weld in different areas is inconsistent (especially 3G upward and 3G downward), which will directly affect the lifting amount setting of the next layer of welding. In addition, as the groove is filled and accumulated, the difference will become more and more obvious. In extreme cases, due to the difference in the accumulated thickness of the weld (for the groove design structure used in this project, the groove width of the whole circle is consistent at the same depth position), the groove width of the next weld in the above-mentioned different areas will be too different, exceeding the limit range that the parameters can cover, resulting in incomplete fusion.

[0083] Therefore, the welding direction is changed after each layer is welded, and the weld formation characteristics of the 8 partitions on the arc are forced to be reversed: when welding the next layer, the 3G downward area of ​​the original previous layer becomes the 3G upward area, and the 3G upward area of ​​the original previous layer becomes the 3G downward area, and the 1G position remains unchanged, so as to ensure that the cumulative thickness of every two layers of welds on the entire arc is consistent (about 7mm). In addition, the weld is narrow and thick when 3G upward welding. Within the groove of limited width, the overlap between welds is less, the interlayer fusion is relatively worse, and it is more likely to produce unfusion defects. The above-mentioned inventive process design inserts a layer of 3G downward weld in the next layer of the original 3G upward area, which can effectively improve the problem of worsening continuous cumulative formation of welds when welding in the 3G upward area.

[0084] At the same time, the changes in groove width are monitored in real time, and single-stage thickness supplementary welding is carried out in different areas for areas with low cumulative thickness. The number of supplementary layers is determined based on the actual measurement results. After supplementary welding, the difference in groove width in each area needs to be reduced, and the target value of the difference is ≤3mm. After completion, the remaining grooves are filled.

[0085] The weld formation characteristics of the 3G upward and 3G downward areas are different. The 3G upward area is narrow and thick, while the 3G downward area is wide and thin. In terms of arc starting and arc ending control, this project sets the arc starting and arc ending points in the 3G downward area according to the characteristics of the weld formation. Set up 4 areas for symmetrical arc starting, such as Figure 5As shown, they are arc starting point 1, arc starting point 2, arc starting point 3 and arc starting point 4. The arc starting position is changed for each layer of welding, and the joint area is staggered by at least 50mm, which can avoid deformation concentration caused by continuous arc starting and closing at the same position. Its advantages are that the molten iron in the 3G downward area has a good spreading effect, the overlapping transition area is smoother, and the molten iron can freely fill the gap area, which is not easy to produce unfusion.

[0086] Specifically, in step S7, the nondestructive testing items include weld surface visual inspection, weld size inspection, weld surface magnetic particle inspection, weld ultrasonic inspection and weld radiographic inspection.

[0087] In summary, the welding robot 1 of the present application is a multi-axial moving structure, which controls the welding swing parameters, can realize high-speed, high-frequency welding swing, and the swing trajectory is more accurate. The addition of swing makes the width of each weld not limited by the filler metal specifications, and realizes free control, thereby reducing the number of welds arranged in each layer, improving welding efficiency, and reducing the risk of unfused between passes; it can make the molten pool more uniform, so that the weld surface is smoother and of better quality, and reduce the subsequent grinding workload; in the swing welding process, the arc also has a stirring effect on the molten pool, which helps to discharge gas, thereby reducing the generation of pores. At the same time, the fine wire pulse submerged arc welding technology is adopted, and the pulse arc impulse has a stirring effect on the molten pool, making the weld more beautiful, the internal metal structure more uniform, and the metallographic structure closer to the parent material; the pulse arc energy is more concentrated, and under the same conditions, it can greatly reduce the input of line energy, refine the grains, and improve the performance of the weld. In addition, the concentrated arc energy can achieve good arc penetration, so that the base metal and filler metal in the arc coverage area can be melted quickly. On the premise of improving the deposition efficiency, the welding speed can be increased, which significantly improves the production efficiency. At the same time, thanks to the good arc penetration, when setting the parameters, there is no need to set the swing dwell time to obtain a good edge fusion effect. The molten iron in the molten pool is confined to the arc pointing area, which effectively improves the problem of uncontrolled escape of the molten pool and poor forming. At the same time, the filament pulse energy is more concentrated, which reduces the degree to which the molten pool is affected by gravity, while ensuring that the melting area has enough heat to allow gas and slag to overflow the weld, perfectly solving the problems of weld unformation, porosity and slag inclusion defects under the continuous up and down slope large angle sudden change structure.

[0088] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Therefore, any modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the technical solution of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A welding process for saddle-shaped welds of hot gas ducts and barrel assemblies, characterized in that: A tool for saddle weld 3G position fine wire swing submerged arc welding, including: A steam generator, a welding robot, an operating platform, a lifting device, an external supporting device, an internal supporting device and a heating component, wherein the steam generator includes a hot gas conduit and a barrel component; The external support device is used to fix the hot gas conduit and the barrel assembly; The operating platform is arranged above the welding area of ​​the hot gas duct and the cylinder assembly; The welding robot and the lifting device are arranged on one side of the hot gas duct and the cylinder assembly; The internal support device is disposed in the hot air conduit and barrel assembly and contacts the inner wall surface of the hot air conduit and barrel assembly; The heating component is connected to the internal support device, and the heating component has a heating end, and the heating end is in contact with the hot air conduit and the inner wall surface of the barrel component; The welding robot comprises a robot support platform, a robot base, a multi-axial moving mechanism, a multi-axial welding arm and a welding gun, wherein the robot base is arranged on the robot support platform, the multi-axial moving mechanism is arranged on the robot base, the multi-axial welding arm is connected to the Z-direction moving end of the multi-axial moving mechanism, and the welding gun is connected to the Z-direction moving end of the multi-axial welding arm; The heating assembly comprises an electric heating device and a plurality of heating plates, the electric heating device is electrically connected to the heating plates, the heating plates form the heating end of the heating assembly, the heating plates are connected to the internal support device, and the heating plates are provided with a saddle-shaped end surface in contact with the hot air conduit and the inner wall surface of the barrel assembly; The welding process comprises the following steps: S1. Fix the hot air conduit and the barrel assembly to the external support device, place the welding robot and the lifting device on one side of the external support device, and install an internal support device and a heating assembly in the hot air conduit and the barrel assembly; S2. Turn on the heating component to preheat the hot air duct and the cylinder component; the preheating temperature range is 175-250°C, and the preheating time is not less than 2 hours; S3, welding the welding groove between the hot gas conduit and the cylinder assembly: s31. First, perform a base weld on the welding groove, then perform a filler weld, and finally perform a cap weld to form a cap weld bead; s32, perform tempering weld at the cap weld and form a tempering weld bead; In step S3, the temperature between the hot gas duct and the barrel assembly is monitored during the welding process to ensure that it does not exceed 250°C. When the workpiece temperature rises due to the welding heat input, the welding area should be cooled naturally in the air until the temperature reaches between 150-250°C before continuing the welding. The recommended temperature difference is ≤50°C. When performing the cover weld, the heating assembly is used to ensure that the temperature of the welding area is between 210-250°C. The welding groove is a saddle-shaped narrow gap groove with a locking groove, the bottom groove width is 22 mm, the groove surface angle is 2°, and the minimum thickness of the pad at the locking groove is 6 mm; The base weld and filler weld of the welding groove are multi-layer and multi-pass welds. The welding direction is changed after each layer is welded. At the same time, the change of groove width is monitored in real time. For the areas with low cumulative thickness, single-stage thickness supplementary welding is carried out in different regions. The number of supplementary layers is determined according to the actual measurement results. After the supplementary welding, the difference in groove width of each area needs to be reduced. The target value of the difference is ≤3mm. After completion, the remaining grooves are filled; In step s31, the welding groove is filled with a filling weld, and the filling weld area is controlled to be flush with the groove edge or within 2 mm below the groove surface before the capping and tempering welds are welded; In steps s31 and s32, the number of the cap welds is more than two, the number of the tempering welds is more than one, one end of the cap weld covers the surface of the welding base material, and the tempering weld overlaps the cap weld and is at 1 / 3 of the width of the cap weld; S4. Post-heat the hot air duct and cylinder assembly; after welding is interrupted or completed, the welding area should be post-heated, the post-heating temperature should be controlled at 250-400℃, and the post-heating time should not be less than 4 hours; S5. heat treating the hot gas duct and the cylinder assembly; S6. Remove the internal support device in the hot gas duct and the cylinder assembly; S7. Perform non-destructive testing on the hot gas duct and cylinder assembly.

2. The welding process for saddle-shaped weld welding of hot gas duct and cylinder assembly according to claim 1 is characterized in that: In step S1, the welding surface of the welding groove between the hot 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 requirement.

3. The welding process for saddle-shaped weld welding of hot gas duct and cylinder assembly according to claim 1 is characterized in that: In step S3, verification coordinate points are established before welding. The number of welding coordinate points is not less than 32. Forward welding and reverse welding can share the welding coordinate points in the middle area. For the arc starting and arc ending areas, independent welding coordinate points need to be set.

4. The welding process for saddle-shaped weld welding of hot gas duct and cylinder assembly according to claim 1 is characterized in that: In step S7, the nondestructive testing items include weld surface visual inspection, weld size inspection, weld surface magnetic particle inspection, weld ultrasonic inspection and weld radiographic inspection.

Images