A reactor pressure vessel nozzle-to-shell welding device and method

Abstract

The present application relates to the technical field of welding tooling and process, and particularly discloses a reactor pressure vessel nozzle and cylinder assembly welding device and method, wherein the reactor pressure vessel nozzle and cylinder assembly welding device comprises a fixing base, an adjusting platform with telescopic rails, a first adjusting column, a roller set, and a mobile operation mechanism which can be moved into the cylinder along the telescopic rails, and is provided with a lifting platform and a nozzle bottom heating device; the cylinder is externally provided with a top nozzle outer side heating device and a bottom nozzle outer side heating device which is composed of an arc-shaped gas heating end driven by a mobile support. The present application can uniformly and continuously heat and keep warm the welding area in all directions, ensure the root cleaning operation under the automatic welding and keeping warm state of the flat welding station, realize the flow welding of multiple nozzles, and greatly improve the welding quality and production efficiency.

Description

Technical Field

[0001] This invention relates to the field of welding tooling and process technology, and in particular to a welding device and method for assembling a reactor pressure vessel nozzle and shell. Background Technology

[0002] A typical nuclear power reactor pressure vessel (RPV) has an outer diameter of approximately Φ5000mm, a height of approximately 3500mm, a nominal thickness of 290mm, and a weight of approximately 155 tons. This assembly has symmetrically arranged three pairs (six) of inlet and outlet water nozzles. The nozzles are connected to the vessel using an insert-type butt weld. The butt weld along the outer cylindrical surface of the vessel has a saddle-shaped structure, with a maximum thickness of 320mm, representing a typical large insert-type saddle weld. The reactor pressure vessel is the site where nuclear fission generates fission heat in a nuclear power plant and is also a key barrier shielding against radioactive materials. It is a crucial piece of equipment ensuring the safe power generation of a nuclear power plant; therefore, the quality of the aforementioned large insert-type saddle weld is of paramount importance to the safety of the nuclear power plant.

[0003] The process requirements for this large-scale insert saddle-shaped weld are extremely stringent: the base material of the weld is high-strength low-alloy steel 16MND5; before welding, the welding area and its surrounding area must be fully and uniformly heated; during the welding process, the welding area and its surrounding area must be kept in a constant state of heat preservation; after welding, a thorough heat treatment to remove hydrogen is required immediately; the weld must be fully penetrated; the maximum weld thickness reaches 320mm, and the welding filler volume of a single weld is about 110kg, resulting in a very large welding volume, high and concentrated welding stress; after welding, an overall heat treatment must be performed in a timely manner to fully eliminate local welding stress; the weld life is up to 60 years, and the weld quality requirements are extremely high; welding must be carried out at the flat welding position most conducive to ensuring weld quality, and welding must be carried out using the automatic welding process most conducive to stable weld quality.

[0004] Conventional vessel nozzles typically employ insert-type saddle-shaped welds, but the weld thickness is almost always less than 100mm. They also lack the aforementioned stringent process requirements, and welding methods are often chosen based on site-specific economic considerations, without the need for large welding systems. Furthermore, the weld quality management procedures for conventional equipment differ from those for nuclear power products; weld repairs during manufacturing or equipment use do not have a significant impact. However, for the aforementioned insert-type saddle-shaped welds of nuclear power RPVs, if delayed defects requiring repair are discovered during their 60-year lifespan, it could escalate into a significant social event or disaster impacting the development of the nuclear power industry. Summary of the Invention

[0005] In view of the above-mentioned shortcomings of the existing technology, the purpose of this invention is to provide a welding device and method for assembling reactor pressure vessel nozzles and cylinders, which can provide all-round, continuous and uniform heating and heat preservation of the welding area, ensure automatic welding at the flat welding station and root cleaning operation under heat preservation, and realize the assembly line welding of multiple nozzles, thereby greatly improving welding quality and production efficiency.

[0006] The above-mentioned technical objective of the present invention is achieved through the following technical solution: In one aspect, the present invention provides a welding apparatus for assembling a reactor pressure vessel nozzle and a cylinder, comprising: A fixed base is provided with a first adjusting column at one end and an adjusting platform at the other end. The adjusting platform is provided with a telescopic rail, the position of which corresponds to the position of the first adjusting column. A roller assembly is provided between the first adjusting column and the adjusting platform. The roller assembly is used to support the cylinder to be welded and allow the cylinder to be welded to rotate around its own axis. A mobile working mechanism is provided on the adjustment platform. The mobile working mechanism can move along the telescopic rail into the cylinder to be welded. A lifting platform is provided on the top surface of the mobile working mechanism. A pipe bottom heating device is provided on the lifting platform. The pipe bottom heating device is used to heat and keep warm the bottom area of ​​the pipe located above the cylinder to be welded. A heating device for the outer side of the top pipe is provided, which is located above the cylinder to be welded and covers the pipe located above the cylinder to be welded. The heating device for the outer side of the top pipe is used to heat and keep the outer surface of the pipe located above the cylinder to be welded. A bottom pipe outer heating device is provided, which is located below the cylinder to be welded, and the position of the bottom pipe outer heating device corresponds to the position of the pipe located below the cylinder to be welded. The bottom pipe outer heating device is used to heat and keep the outer surface of the pipe located below the cylinder to be welded.

[0007] Compared to existing technologies, this application achieves stable support and flexible repositioning of large cylinders by cooperating with a first adjusting column at one end of a fixed base and an adjusting platform at the other end, and by setting a roller group between them to support the cylinder to be welded and allow it to rotate around its own axis. This allows the welder to always operate in a flat welding position, facilitating the use of automated welding processes and effectively ensuring the welding quality of thick-walled saddle-shaped welds. Simultaneously, the mobile working mechanism can extend into the cylinder along the telescopic rail on the adjusting platform, and the heating device at the bottom of the connecting pipe on its lifting platform can heat and insulate the area at the bottom of the connecting pipe located above the cylinder, in conjunction with the cover... The heating device on the outer side of the top nozzle on the upper nozzle and the heating device on the outer side of the bottom nozzle on the fixed base corresponding to the position of the lower nozzle achieve all-round synchronous heating and insulation of the inner bottom, outer top and outer bottom of the nozzle. This ensures that the welding area and surrounding area are always in a sufficient, uniform and controllable insulation state throughout the welding process, meeting the strict process requirements of 16MND5 high-strength low alloy steel for preheating temperature, interpass temperature and post-weld insulation. This effectively controls welding stress, prevents cold cracking, and ultimately ensures the quality and long-term operational reliability of the welded joint between the reactor pressure vessel nozzle and the shell assembly.

[0008] As a preferred embodiment of the present invention, the adjustment platform includes: a platform body, the platform body is provided with a second adjustment column, the second adjustment column is provided with an adjustment guide rail, the second adjustment column is used to adjust the height of the adjustment guide rail, the adjustment guide rail is provided with a storage groove, the telescopic rail is disposed in the storage groove, and the telescopic rail can extend or retract along the length direction of the storage groove.

[0009] The above-mentioned solution uses a second adjusting column to adjust the height of the adjusting guide rail, and a storage slot is provided on the adjusting guide rail to allow the telescopic rail to extend or retract. On the one hand, this allows the adjusting guide rail to be adjusted to different heights according to actual needs, thereby matching different types of RPVs and achieving the purpose of leveling and fixing the guide rail. On the other hand, the telescopic rail can be completely retracted into the storage slot when not in use, reducing the overall space occupied by the device, facilitating the transfer, storage and on-site layout of the device, and improving the site adaptability and usage flexibility of the device, which is especially suitable for space-constrained working environments such as nuclear power manufacturing workshops.

[0010] As a preferred embodiment of the present invention, the second adjusting column includes: The second column body has one end connected to the fixed base or the ground, and the other end connected to the platform body. The second support part is located above the second column body and connected to the bottom wall of the adjusting guide rail. The second support part is connected to the second column body through a screw lifting structure.

[0011] The above-mentioned solution features a screw-lifting structure with good self-locking, high adjustment accuracy, and strong load-bearing capacity. It can precisely fine-tune the height of the platform body, ensuring that the platform can achieve a high-precision level under different ground conditions. This provides a reliable foundation for the smooth reciprocating motion of the mobile working mechanism along the telescopic rail, avoiding wheel jamming or deviation of the mobile working mechanism due to platform tilt, and indirectly ensuring the alignment accuracy of the welding station and the overall welding quality.

[0012] As a preferred embodiment of the present invention, the first adjusting column includes: The first column body, one end of which is connected to the fixed base or the ground; The first support part is positioned corresponding to the position of the telescopic rail, and the first support part is connected to the first column body via a screw lifting structure.

[0013] By adopting the above solution, the end support height and levelness of the telescopic rail can be precisely adjusted, ensuring the docking accuracy and flatness between the telescopic rail and the adjustment platform. This ensures that the wheels of the mobile operating mechanism can travel smoothly on the telescopic rail without derailment or jamming, and also ensures the positioning accuracy of the mobile operating mechanism when it reciprocates inside the cylinder. This provides a reliable track foundation for the heating device at the bottom of the pipe to be accurately aligned with the bottom of the pipe.

[0014] As a preferred embodiment of the present invention, the mobile working mechanism includes a frame, the bottom of which is provided with wheels, the positions of which correspond to the positions of the telescopic rails; the bottom of the frame is provided with a lifting device, and a lifting platform is provided on the top wall of the frame.

[0015] The above-mentioned solution uses a vehicle frame structure with wheels at the bottom corresponding to the positions of the telescopic rails, enabling it to move smoothly back and forth inside the cylinder along the telescopic rails. This allows for flexible switching of welding stations within the axial range of the cylinder. At the same time, the bottom of the vehicle frame integrates a lifting device, which can directly hoist heavy equipment such as the top working platform, bottom working platform, automatic welding machine, and root cleaning machine during movement or after arriving at the designated work station. This eliminates the need for additional lifting equipment, simplifies on-site equipment configuration, improves work efficiency, and makes the equipment scheduling of the entire welding process more compact and orderly.

[0016] As a preferred embodiment of the present invention, the lifting platform is a screw lifting device, the fixed end of the screw lifting device is connected to the top surface of the mobile working mechanism, and the bottom heating device of the connecting pipe is disposed on the lifting end of the screw lifting device.

[0017] The above-mentioned solution uses a screw-driven lifting device for the lifting platform. Its fixed end is connected to the top surface of the mobile working mechanism, and the bottom heating device of the pipe is set on the lifting end. The screw-driven lifting structure has the advantages of smooth lifting, accurate positioning, strong load-bearing capacity and self-locking. It can accurately lift the bottom heating device of the pipe to a position that is in close contact with the bottom of the pipe to be welded, ensuring that the electric heating element is in full contact with the bottom of the pipe, achieving uniform heating and heat preservation of the bottom area of ​​the pipe. At the same time, it can maintain the stability of the heating device position during the welding process, avoiding uneven heating due to vibration or displacement, which would affect the weld quality.

[0018] As a preferred embodiment of the present invention, the bottom heating device of the connecting pipe includes a bottom heating end and a bottom fixing seat. The bottom fixing seat is disposed on the top wall of the lifting end, and the bottom heating end is disposed on the bottom fixing seat. The shape of the bottom heating end corresponds to the shape of the inner wall of the cylinder to be welded. The outer heating device of the top pipe includes a top heating end and a top abutment seat. The top abutment seat is provided with a through hole. The diameter of the through hole is less than or equal to the inner diameter of the pipe. The top heating end has a cylindrical structure. The inner cavity shape of the cylindrical structure is adapted to the outer contour shape of the pipe. The top heating end is located at the top abutment seat corresponding to the through hole, and the axis of the top heating end coincides with the axis of the through hole. Both the top heating end and the bottom heating end are electric heating elements.

[0019] Using the above-mentioned scheme, the shape of the bottom heating end corresponds to the shape of the inner wall of the cylinder to be welded, and the top heating end has a cylindrical structure with an inner cavity shape that matches the outer contour of the nozzle. This allows both heating ends to fit tightly against the nozzle or cylinder, significantly improving the uniformity of heating and heat conduction efficiency, and effectively reducing heat loss. At the same time, both the bottom heating end and the top heating end use electric heating elements. Electric heating has the advantages of precise temperature control, fast response speed, and cleanliness without pollution. It can accurately meet the strict process requirements of 16MND5 material for preheating temperature and interpass temperature, ensuring that the welding area and surrounding area are always in a stable and controllable heat preservation state throughout the welding process, thereby ensuring the welding quality of the saddle-shaped thick weld.

[0020] As a preferred embodiment of the present invention, the heating device on the outer side of the bottom pipe includes at least two arc-shaped heating ends and at least two movable supports. The bottom of the movable supports is provided with wheels. Each movable support is provided with at least one arc-shaped heating end. The arc-shaped heating end is a gas heating device, and the arc-shaped heating end has an arc-shaped heating surface that is adapted to the outer contour shape of the pipe. The at least two movable supports are configured to perform relative opening and closing movements to drive their respective corresponding arc-shaped heating ends to move closer or further apart; when the arc-shaped heating ends move closer to each other to the working position, the arc-shaped heating ends approach the outer contour of the pipe from multiple circumferential sides of the pipe below the cylinder to be welded, thereby heating and insulating the outer surface of the pipe.

[0021] The above-mentioned scheme employs at least two arc-shaped heating ends in conjunction with a movable support that can be opened and closed relative to each other. Each arc-shaped heating end is a gas-fired heating device with an arc-shaped heating surface that matches the outer contour of the pipe. Gas heating has the advantages of high heat power and fast heating speed, which can meet the high heat input requirements of thick-walled pipes (weld thickness up to 320mm). Multiple arc-shaped heating ends simultaneously heat the outer contour of the pipe from multiple sides around the pipe circumference, achieving all-round uniform heating of the outer surface of the pipe and avoiding local overheating or insufficient heating. The movable support is equipped with wheels at the bottom and can be opened and closed relative to each other, making the heating device easy to install and remove, and flexible enough to adapt to different pipe outer diameters, thus improving the versatility and ease of operation of the device.

[0022] As a preferred embodiment of the present invention, it further includes a top working platform and a bottom working platform. The top working platform is disposed above the cylinder to be welded and contacts the outer surface of the cylinder to be welded. The position of the top working platform corresponds to the position of the connecting pipe, and the shape of the bottom wall of the top working platform corresponds to the contour of the outer surface of the cylinder to be welded. The bottom working platform is set inside the cylinder to be welded and located below the mobile working mechanism, and the shape of the bottom wall of the bottom working platform corresponds to the shape of the inner wall of the cylinder to be welded.

[0023] With the above solution, the top working platform is in contact with the outer surface of the cylinder to be welded and the shape of the bottom wall is adapted to the outer contour of the cylinder. The bottom working platform is set inside the cylinder and the shape of the bottom wall is adapted to the shape of the inner wall of the cylinder. The two provide stable operating support parts that are completely in contact with the curved surface of the cylinder for welding operations on the outer and inner sides of the cylinder, respectively, and provide a safe working space for operators.

[0024] In another aspect, the present invention provides a method for welding the nozzle and the shell of a reactor pressure vessel, which includes the following steps: S1: Fix the fixed base, level the adjustment platform through the second adjustment column, and put the telescopic rail in the storage state; set up the mobile working mechanism on the adjustment platform; hoist the cylinder to be welded onto the roller group, adjust the roller group to support the cylinder to be welded and enable it to rotate around its own axis, rotate the cylinder to be welded so that the top pipe installation position and the bottom pipe installation position are respectively above and below in the vertical direction. S2: Pull the telescopic rail out of the adjustment platform and connect it to the first adjustment column and fasten it. Level the telescopic rail through the first adjustment column and move the working mechanism back and forth along the telescopic rail to verify the work station. S3: Hoist the top working platform so that it contacts the outer surface of the cylinder to be welded; hoist the first connecting pipe and position it at the connecting pipe installation position above the cylinder to be welded; move the mobile working mechanism along the telescopic rail to the bottom of the first connecting pipe, and use the lifting platform to raise the heating device at the bottom of the connecting pipe and press it against the bottom of the first connecting pipe for heating and heat preservation; hoist the outer heating device of the top connecting pipe and cover the first connecting pipe with the outer heating device to heat and preserve the outer surface of the first connecting pipe; hoist the automatic welding machine and install and fix the automatic welding machine on the first connecting pipe; after preheating to the required temperature and uniform temperature, use the automatic welding machine to weld the outer weld of the first connecting pipe; S4: After the outer side of the first connector is welded, remove the outer heating device of the top connector, the top working platform, and the automatic welding machine. Rotate the cylinder to be welded 180° using the roller set so that the first connector is at the bottom. At this time, the welding position that was originally located below the cylinder to be welded in the vertical direction is now above the cylinder in the vertical direction. Move and close the arc-shaped heating ends of the outer heating device of the bottom connector to the outer surface of the first connector to heat and keep the first connector warm. The moving working mechanism uses its lifting device to hoist the bottom working platform into the cylinder to be welded and support it on the inner wall of the cylinder. Then, hoist the root cleaning machine and complete the root cleaning of the weld seam of the first connector under the heat preservation condition. After the root cleaning is completed, remove the root cleaning machine and then hoist the automatic welding machine to weld the inner weld seam of the first connector under the same heat preservation condition. S5: While performing step S4 to clean the root of the weld on the outside of the first pipe and weld the inside, perform the welding operation on the outside of the pipe in step S3 on the second pipe. S6: After completing the welding of the outer side of the second nozzle, the root cleaning of the outer weld of the first nozzle, and the welding of the inner side of the first nozzle, remove the heating device on the outer side of the top nozzle, the top working platform, the automatic welding machine on the outer side of the cylinder, and the bottom working platform, the root cleaning machine, and the automatic welding machine on the inner side of the cylinder; rotate the cylinder to be welded 180° again, so that the second nozzle is at the bottom and the first nozzle is at the top; move and close the arc-shaped heating ends of the heating device on the outer side of the bottom nozzle to the outer surface of the second nozzle for heating and heat preservation; move the working mechanism to hoist the bottom working platform and hoist the root cleaning machine and the automatic welding machine in sequence to complete the root cleaning of the outer weld and the welding of the inner side of the second nozzle respectively; while the second nozzle is being cleaned of the outer weld and welded on the inner side, hoist the heating device on the outer side of the top nozzle and cover the first nozzle to heat and preserve the outer surface of the first nozzle; S7: After all welding is completed, remove all heating devices, work platforms and automatic welding machines; move the working mechanism back to the adjustment platform along the telescopic rail, and retract the telescopic rail into the storage tank; lift the cylinder to be welded away and perform overall stress relief heat treatment.

[0025] Compared to existing technologies, this application enables simultaneous welding of the outer side of one nozzle and the outer side of another nozzle by rotating the cylinder 180°, allowing the outer side welding of both nozzles to be completed almost simultaneously, significantly shortening the overall construction period. After the outer side welding is completed, the root cleaning and inner side welding are performed sequentially by maintaining a heated and insulated state. The cylinder is rotated again to alternately position the two nozzles at the bottom for inner side operations, achieving parallel alternation of root cleaning and welding, and the operation of the two nozzles, minimizing waiting time. Throughout the entire welding process, the nozzles and cylinder are kept heated and insulated, meeting the stringent process requirements of 16MND5 material for preheating, interpass temperature, and post-weld insulation. At the same time, the use of a flat welding station combined with automatic welding ensures the full penetration quality of the 320mm thick saddle-shaped weld. Finally, after welding, an overall stress-relieving heat treatment is performed to fully eliminate residual welding stress and ensure the long-term reliability of the weld.

[0026] The aforementioned welding device and method for assembling reactor pressure vessel nozzles and cylinders has the following beneficial effects: By providing an adjustment platform with first adjusting columns and integrated telescopic rails at both ends of the fixed base, and cooperating with roller sets to support the cylinder rotation, a stable track that can extend into the cylinder is provided for the mobile operating mechanism, ensuring that each nozzle can always be welded in a flat welding position in the vertical direction. Simultaneously, through the coordinated action of the three heating devices—a bottom heating device for the nozzle at the top of the mobile operating mechanism, a top nozzle outer heating device covering the upper nozzle, and a bottom nozzle outer heating device corresponding to the lower nozzle—a comprehensive, close-fitting heating and insulation system is formed over the welding area, effectively solving the problem of insufficient and uniform heating of large insert saddle-shaped welds in nuclear power reactor pressure vessels during preheating and welding, significantly improving weld quality. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of a welding device for assembling the nozzle and the cylinder of a reactor pressure vessel according to the present invention; Figure 2 This is a side view of a welding device for assembling a reactor pressure vessel nozzle and a cylinder according to the present invention. Figure 3 This is a schematic diagram of the structure of the fixing seat in the welding device for assembling the nozzle and cylinder of a reactor pressure vessel according to the present invention; Figure 4 This is a side view of the fixing seat in the welding device for assembling the nozzle and cylinder of a reactor pressure vessel according to the present invention; Figure 5 This is a schematic diagram of the heating device at the bottom of the nozzle in a welding device for assembling a nozzle and a cylinder of a reactor pressure vessel according to the present invention. Figure 6 This is a schematic diagram of the moving operation mechanism in the welding device for assembling the nozzle and cylinder of a reactor pressure vessel according to the present invention; Figure 7 This is a schematic diagram of the heating device on the outside of the top nozzle in a welding device for assembling the nozzle and the cylinder of a reactor pressure vessel according to the present invention. Figure 8 This is a schematic diagram of the heating device on the outside of the bottom nozzle in a welding device for assembling the nozzle and the cylinder of a reactor pressure vessel according to the present invention. In the diagram: 1. Fixed base; 2. First adjusting column; 21. First column body; 22. First support part; 3. Adjusting platform; 31. Platform body; 32. Second adjusting column; 321. Second column body; 322. Second support part; 33. Storage slot; 34. Adjusting guide rail; 4. Telescopic rail; 5. Roller assembly; 6. Mobile operating mechanism; 61. Frame; 62. Wheel; 63. Lifting device; 7. Lifting platform; 71. Fixed end; 72. Lifting end; 8. Bottom heating device for connecting pipe 81. Bottom heating end; 82. Bottom fixed seat; 9. Top pipe outer heating device; 91. Top heating end; 92. Top abutment seat; 93. Through hole; 10. Bottom pipe outer heating device; 101. Arc-shaped heating end; 101a. Arc-shaped heating surface; 102. Moving bracket; 103. Walking wheel; 11. Top working platform; 12. Bottom working platform; 13. First pipe; 14. Second pipe; 15. Cylinder to be welded; 16. Automatic welding machine; 17. Root cleaning machine.

[0028] 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

[0029] To make the above-mentioned objectives and beneficial effects of the present invention more apparent and easily understood, the following detailed description, in conjunction with the accompanying drawings and multiple embodiments, will provide a detailed account of a reactor pressure vessel nozzle and cylinder welding device and method provided by the present invention. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0030] 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.

[0031] 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.

[0032] Example 1 See Figure 1 and Figure 2 This application provides a welding device for assembling a reactor pressure vessel nozzle and its shell, mainly used for welding large insert saddle-shaped welds between the shell and inlet / outlet water nozzles of a nuclear power reactor pressure vessel (RPV). The shell 15 to be welded has an outer diameter of approximately Φ5000mm, a height of approximately 3500mm, a nominal thickness of 290mm, and a weight of approximately 155 tons. Six nozzle installation positions are symmetrically arranged on the shell 15, for installing six inlet / outlet water nozzles. The welding device includes a fixed base 1, a moving working mechanism 6, a top nozzle outer heating device 9, and a bottom nozzle outer heating device 10. The fixed base 1 is set on the ground at the work station. One end of the fixed base 1 is equipped with a first adjusting column 2, and the other end is equipped with an adjusting platform 3. The adjusting platform 3 is equipped with a telescopic rail 4, the position of which corresponds to the position of the first adjusting column 2. A roller assembly 5 is provided between the first adjusting column 2 and the adjusting platform 3. The roller assembly 5 supports the cylinder 15 to be welded and allows it to rotate around its own axis. The roller assembly 5 is a general-purpose device, belonging to the conventional roller frame assembly used in the prior art for supporting cylinders. It drives the cylinder to rotate through the friction between the drive roller and the outer wall of the cylinder 15 to complete the switching between different work positions. This application does not make any improvements to the structure of the roller assembly 5, and will not be described further here.

[0033] See Figure 1 , Figure 2 and Figure 5 The mobile working mechanism 6 is mounted on the adjusting platform 3 and can move along the telescopic rail 4 into the cylinder 15 to be welded. A lifting platform 7 is mounted on the top surface of the mobile working mechanism 6, and a pipe bottom heating device 8 is mounted on the lifting platform 7. The pipe bottom heating device 8 is used to heat and insulate the bottom area of ​​the pipe (i.e., the first pipe 13) located above the cylinder 15 to be welded. The mobile working mechanism 6 includes a frame 61, and wheels 62 are mounted on the bottom of the frame 61, with the positions of the wheels 62 corresponding to the positions of the telescopic rail 4. The wheels 62 can travel along the adjusting guide rail 34 or the telescopic rail 4, thereby driving the entire mobile working mechanism 6 to reciprocate along the telescopic rail 4. A lifting device 63 is mounted on the bottom of the frame 61, and the lifting platform 7 is mounted on the top wall of the frame 61. The lifting device 63 is a conventional hand chain hoist. By pulling the manual chain and rotating the hand chain wheel, the friction plate ratchet and brake seat are pressed together and rotate. The long gear shaft then rotates the plate gear, the short gear shaft, and the splined gear. The lifting sprocket mounted on the splined gear drives the lifting chain, thereby smoothly lifting or lowering the heavy object. In other embodiments, the lifting device 63 can also be an electric hoist or a hydraulic lifting device, as long as it can achieve the lifting function. The specific type of the lifting device 63 is not limited here.

[0034] The fixed end 71 of the lifting platform 7 is connected to the top wall of the frame 61, and the bottom heating device 8 is mounted on the lifting end 72 of the lifting platform 7. In this embodiment, the lifting platform 7 adopts a screw lifting device in the prior art, such as a scissor lift platform driven by a screw structure. The working platform can be raised or lowered by rotating the screw. In other embodiments, the lifting platform 7 can also be a hydraulic lifting platform or an electric push rod lifting platform, as long as it can realize the lifting and lowering of the bottom heating device 8. The specific type of the lifting platform 7 is not limited here.

[0035] See Figure 1 , Figure 2 and Figure 6 The bottom heating device 8 of the connecting pipe includes a bottom heating end 81 and a bottom fixing seat 82. The bottom fixing seat 82 is disposed on the top wall of the lifting end 72, and the bottom heating end 81 is disposed on the bottom fixing seat 82. The shape of the bottom heating end 81 corresponds to the shape of the inner wall of the cylinder 15 to be welded, so as to ensure that the bottom heating end 81 can fit against the inner wall of the cylinder 15 to be welded and the bottom area of ​​the connecting pipe above the cylinder 15 to be welded for uniform heating. The bottom heating end 81 is a conventional electric heating element in the prior art, such as a track-type ceramic heater, which is made of high-temperature resistant high-quality nickel-chromium resistance wire and high-grade ceramic insulating devices. In some other embodiments, the bottom heating end 81 can also be other types of electric heaters, as long as they can achieve the heating and heat preservation functions, and the specific type of the bottom heating end 81 is not limited here.

[0036] See Figure 1 , Figure 2 and Figure 7 A top-mounted outer heating device 9 is positioned above the cylinder 15 to be welded and covers the connecting pipe located above the cylinder 15. The top-mounted outer heating device 9 is used to heat and insulate the outer surface of the connecting pipe located above the cylinder 15. The top-mounted outer heating device 9 includes a top heating end 91 and a top abutment seat 92. The top abutment seat 92 has a through hole 93, the diameter of which is less than or equal to the inner diameter of the connecting pipe. The top heating end 91 has a cylindrical structure, the inner cavity shape of which matches the outer contour shape of the connecting pipe. The top heating end 91 is positioned at the top abutment seat 92 corresponding to the through hole 93, and the axis of the top heating end 91 coincides with the axis of the through hole 93. In use, the top-mounted outer heating device 9 covers the connecting pipe from above, with the inner wall of the top heating end 91 close to the outer surface of the connecting pipe, heating and insulating the outer surface of the connecting pipe. The top heating end 91 is a conventional electric heating element in the prior art, such as a tracked ceramic heater. In other embodiments, the top heating end 91 can also be other forms of electric heaters, as long as they can achieve the heating and heat preservation functions. The specific type of the top heating end 91 is not limited here.

[0037] See Figure 1 , Figure 2 and Figure 8 The bottom pipe outer heating device 10 is located below the cylinder 15 to be welded, and its position corresponds to the position of the pipe (i.e., the first pipe 13 or the second pipe 14 rotated to the bottom) located below the cylinder 15 to be welded. The bottom pipe outer heating device 10 is used to heat and insulate the outer surface of the pipe located below the cylinder 15 to be welded. The bottom pipe outer heating device 10 includes at least two arc-shaped heating ends 101 and at least two movable supports 102. The bottom of the movable supports 102 is provided with wheels 103, and each movable support 102 is provided with at least one arc-shaped heating end 101. In this embodiment, there are two arc-shaped heating ends 101 and two movable supports 102, and one arc-shaped heating end 101 is fixedly installed on each movable support 102. The arc-shaped heating end 101 is a gas heating device in the prior art, such as a flame burner using liquefied petroleum gas as fuel. The arc-shaped heating end 101 has an arc-shaped heating surface 101a that is adapted to the outer contour shape of the pipe.

[0038] Two movable supports 102 are configured to open and close relative to each other, causing their respective arc-shaped heating ends 101 to move closer or further apart. In this embodiment, the two movable supports 102 are independently set and not connected. In other embodiments, the two movable supports 102 can be connected together by hinges, allowing them to open and close relative to each other. When the arc-shaped heating ends 101 approach each other to the working position, each arc-shaped heating end 101 approaches the outer contour of the connecting pipe from multiple sides circumferentially below the cylinder 15 to be welded, thereby heating and insulating the outer surface of the connecting pipe. Specifically, when the connecting pipe is located below the cylinder 15 to be welded, the movable supports 102 move towards the connecting pipe via the traveling wheels 103, causing the arc-shaped heating ends 101 to close around the outer periphery of the connecting pipe, with the arc-shaped heating surface 101a close to the outer surface of the connecting pipe, using the heat generated by the combustion of gas to heat and insulate the connecting pipe. When it is necessary to move them away, the movable supports 102 move away from the connecting pipe, and the arc-shaped heating ends 101 move away from each other, making room for operation.

[0039] See Figures 1 to 4 The adjustment platform 3 includes a platform body 31, with second adjustment columns 32 located at each of the four corners of the platform body 31. Adjustment guide rails 34 are mounted on the second adjustment columns 32, and the second adjustment columns 32 are used to adjust the height of the adjustment guide rails 34. The adjustment guide rails 34 have storage slots 33, and telescopic rails 4 are housed within the storage slots 33, extending or retracting along the length of the storage slots 33. When the telescopic rails 4 extend, their ends connect to the first adjustment columns 2, forming a track for the mobile operating mechanism 6 to travel on; when the telescopic rails 4 retract, they are completely contained within the storage slots 33, without occupying external space.

[0040] The platform body 31 is also equipped with conventional work platform components such as ladders and guardrails in the prior art to ensure the safety of operators when working on the platform body 31.

[0041] The second adjusting column 32 includes a second column body 321 and a second support part 322. One end of the second column body 321 is connected to the fixed base 1 or the ground, and the side of the other end is welded to the platform body 31. The second support part 322 is located above the second column body 321 and connected to the bottom wall of the platform body 31. The second support part 322 is connected to the second column body 321 through a screw lifting structure. The screw lifting structure is a conventional screw lifting structure in the prior art. For example, the screw is rotated by turning a handwheel, thereby adjusting the height of the second support part 322 of the second adjusting column 32, thereby achieving leveling of the platform body 31. In some other embodiments, the second adjusting column 32 can also achieve height adjustment through a hydraulic lifting structure or a worm gear lifting structure, as long as leveling of the platform body 31 can be achieved. The specific lifting method of the second adjusting column 32 is not limited here.

[0042] See appendix Figure 4 The first adjusting column 2 includes a first column body 21 and a first support part 22. One end of the first column body 21 is connected to the fixed base 1 or the ground. The position of the first support part 22 corresponds to the position of the telescopic rail 4, and the first support part 22 is connected to the first column body 21 through a screw lifting structure. When the telescopic rail 4 extends from the storage slot 33, the end of the telescopic rail 4 is mounted on the first support part 22. The height of the first support part 22 is adjusted by the screw lifting structure to keep the telescopic rail 4 horizontal. The screw lifting structure is a conventional screw lifting structure in the prior art, such as rotating the screw by turning a handwheel, thereby adjusting the height of the first support part 22 of the first adjusting column 2. In some other embodiments, the first adjusting column 2 can also use a hydraulic lifting structure or a worm gear lifting structure to achieve height adjustment, as long as the telescopic rail 4 can be leveled. The specific lifting method of the first adjusting column 2 is not limited here.

[0043] See Figure 1 and Figure 2The welding assembly also includes a top working platform 11 and a bottom working platform 12. The top working platform 11 is positioned above the cylinder 15 to be welded and contacts the outer surface of the cylinder 15. The position of the top working platform 11 corresponds to the position of the connecting pipe. The shape of the bottom wall of the top working platform 11 corresponds to the contour of the outer surface of the cylinder 15 to ensure that the top working platform 11 can be stably mounted on the outer wall of the cylinder 15. The top working platform 11 serves as a working platform for operators, providing a safe working environment, and includes conventional working platform components such as ladders and guardrails. The bottom working platform 12 is located inside the cylinder 15 to be welded and below the moving working mechanism 6. The shape of the bottom wall of the bottom working platform 12 corresponds to the shape of the inner wall of the cylinder 15 to ensure that the bottom working platform 12 can be stably supported on the inner wall of the cylinder 15. The bottom working platform 12 also serves as a working platform for operators, providing a safe working environment, and includes conventional working platform components such as ladders and guardrails.

[0044] Example 2 This embodiment provides a method for welding the nozzle and shell of a reactor pressure vessel, using the welding apparatus described in Embodiment 1 for the welding operation, including the following steps: Step S1: Fix the fixed base 1, level the adjusting platform 3 using the second adjusting column 32, and retract the telescopic rail 4. Use a workshop crane to mount the mobile working mechanism 6 onto the adjusting guide rail 34 on the adjusting platform 3. Use the workshop crane to hoist the cylinder 15 to be welded onto the roller assembly 5, and adjust the roller assembly 5 to support the cylinder 15 and allow it to rotate around its own axis. Rotate the cylinder 15 so that the top and bottom connecting pipe installation positions are vertically above and below, respectively.

[0045] Step S2: Pull the telescopic rail 4 out from the adjustment platform 3 and connect and secure it to the first adjustment column 2. Level the telescopic rail 4 using the first adjustment column 2. Move the mobile working mechanism 6 back and forth along the telescopic rail 4 to verify the work position and ensure that the mobile working mechanism 6 can move smoothly to the working position inside the cylinder 15 to be welded.

[0046] Step S3: The overhead crane hoists the top working platform 11, bringing it into contact with the outer surface of the cylinder 15 to be welded. The overhead crane hoists the first connecting pipe 13 and positions it above the cylinder 15 at the connecting pipe installation location. The moving working mechanism 6 moves along the telescopic rail 4 to below the first connecting pipe 13, and the lifting platform 7 raises the bottom heating device 8 of the connecting pipe, placing it against the bottom of the first connecting pipe 13 for heating and insulation. The overhead crane hoists the outer heating device 9 of the top connecting pipe, covering the first connecting pipe 13 to heat and insulate its outer surface. The overhead welding machine 16 is hoisted by the overhead crane and installed and fixed onto the first connecting pipe 13. After preheating to the required temperature and achieving uniform temperature, the automatic welding machine 16 is used to weld the outer weld of the first connecting pipe 13.

[0047] Step S4: After the outer side of the first connecting pipe 13 is welded, remove the top connecting pipe outer heating device 9, the top working platform 11, and the automatic welding machine 16. Use the roller group 5 to rotate the cylinder 15 to be welded 180°, so that the first connecting pipe 13 is rotated to the bottom. At this time, the welding position that was originally located below the vertical direction of the cylinder 15 to be welded is now above the vertical direction. Move and close the arc-shaped heating ends 101 of the bottom connecting pipe outer heating device 10 to be close to the outer surface of the first connecting pipe 13 to heat and keep the first connecting pipe 13 warm. The moving working mechanism 6 uses its lifting device 63 to hoist the bottom working platform 12 into the cylinder 15 to be welded and support it on the inner wall of the cylinder. Then, hoist the root cleaning machine 17 and complete the root cleaning of the outer weld of the first connecting pipe 13 under the heat preservation state. After the root cleaning is completed, remove the root cleaning machine 17 and then hoist the automatic welding machine 16 to weld the inner weld of the first connecting pipe 13 under the same heat preservation state.

[0048] Step S5: While performing the root cleaning and inner welding of the outer weld of the first connector 13 in step S4, perform the outer welding operation of the connector in step S3 on the second connector 14.

[0049] Step S6: After completing the welding of the outer side of the second connector 14, the root cleaning of the outer weld of the first connector 13, and the welding of the inner side of the first connector 13, remove the top connector outer heating device 9, the top working platform 11, and the automatic welding machine 16 from the outer side of the cylinder, and the bottom working platform 12, the root cleaning machine 17, and the automatic welding machine 16 from the inner side of the cylinder. Rotate the cylinder 15 to be welded 180° again, so that the second connector 14 is at the bottom and the first connector 13 is at the top. Move and close the arc-shaped heating ends 101 of the bottom connector outer heating device 10 to the outer surface of the second connector 14 for heating and heat preservation. Move the working mechanism 6 to hoist the bottom working platform 12 and hoist the root cleaning machine 17 and the automatic welding machine 16 in sequence to complete the root cleaning of the outer weld and the welding of the inner side of the second connector 14. While the second connector 14 is being welded on the outer side and the inner side, hoist the top connector outer heating device 9 and cover the first connector 13 with it to heat and preserve the outer surface of the first connector 13.

[0050] Step S7: After all welding is completed, remove all heating devices, work platforms, and automatic welding machine 16. Move the working mechanism 6 back along the telescopic rail 4 to the adjustment platform 3, and retract the telescopic rail 4 into the storage slot 33. Lift the cylinder 15 to be welded away for overall stress-relieving heat treatment.

[0051] It is worth noting that the automatic welding machine 16 in this embodiment is a rotary welding machine for special-purpose pipe-type circumferential welds in the prior art. It is fixed to the inner wall of the pipe by a fixing device and is used for automatic welding of the pipe circumferential weld. The root cleaning machine 17 is fixed and installed in a similar way to the automatic welding machine 16. It is also fixed to the inner wall of the pipe by a fixing device. The root cleaning machine 17 is installed and fixed by a fixing device.

[0052] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made under the inventive concept of the present invention using the contents of the present invention specification and drawings, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A welding device for assembling a reactor pressure vessel nozzle and a vessel shell, characterized in that, include: A fixed base is provided with a first adjusting column at one end and an adjusting platform at the other end. The adjusting platform is provided with a telescopic rail, the position of which corresponds to the position of the first adjusting column. A roller assembly is provided between the first adjusting column and the adjusting platform. The roller assembly is used to support the cylinder to be welded and allow the cylinder to be welded to rotate around its own axis. A mobile working mechanism is provided on the adjustment platform. The mobile working mechanism can move along the telescopic rail into the cylinder to be welded. A lifting platform is provided on the top surface of the mobile working mechanism. A pipe bottom heating device is provided on the lifting platform. The pipe bottom heating device is used to heat and keep warm the bottom area of ​​the pipe located above the cylinder to be welded. A heating device for the outer side of the top pipe is provided, which is located above the cylinder to be welded and covers the pipe located above the cylinder to be welded. The heating device for the outer side of the top pipe is used to heat and keep the outer surface of the pipe located above the cylinder to be welded. A bottom pipe outer heating device is provided, which is located below the cylinder to be welded, and the position of the bottom pipe outer heating device corresponds to the position of the pipe located below the cylinder to be welded. The bottom pipe outer heating device is used to heat and keep the outer surface of the pipe located below the cylinder to be welded.

2. The assembly and welding device for the reactor pressure vessel nozzle and shell according to claim 1, characterized in that, The adjustment platform includes: a platform body, a second adjustment column, an adjustment guide rail on the second adjustment column, the second adjustment column being used to adjust the height of the adjustment guide rail, the adjustment guide rail having a storage groove, a telescopic rail being disposed in the storage groove, and the telescopic rail being able to extend or retract along the length direction of the storage groove.

3. The reactor pressure vessel nozzle and cylinder assembly welding device according to claim 2, characterized in that, The second adjusting column includes: The second column body has one end connected to the fixed base or the ground, and the other end connected to the platform body. The second support part is located above the second column body and connected to the bottom wall of the adjusting guide rail. The second support part is connected to the second column body through a screw lifting structure.

4. The assembly and welding device for the reactor pressure vessel nozzle and shell according to claim 1, characterized in that, The first adjusting column includes: The first column body, one end of which is connected to the fixed base or the ground; The first support part is positioned corresponding to the position of the telescopic rail, and the first support part is connected to the first column body via a screw lifting structure.

5. The assembly and welding device for the reactor pressure vessel nozzle and shell according to claim 1, characterized in that: The mobile working mechanism includes a frame, with wheels at the bottom of the frame, the positions of which correspond to the positions of the telescopic rails; a lifting device is provided at the bottom of the frame, and a lifting platform is provided on the top wall of the frame.

6. The assembly and welding device for the reactor pressure vessel nozzle and shell according to claim 1, characterized in that: The lifting platform is a screw jack, the fixed end of which is connected to the top surface of the mobile working mechanism, and the bottom heating device of the connecting pipe is installed on the lifting end of the screw jack.

7. The reactor pressure vessel nozzle and shell welding device according to claim 6, characterized in that: The bottom heating device of the pipe includes a bottom heating end and a bottom fixing seat. The bottom fixing seat is disposed on the top wall of the lifting end, and the bottom heating end is disposed on the bottom fixing seat. The shape of the bottom heating end corresponds to the shape of the inner wall of the cylinder to be welded. The outer heating device of the top pipe includes a top heating end and a top abutment seat. The top abutment seat is provided with a through hole. The diameter of the through hole is less than or equal to the inner diameter of the pipe. The top heating end has a cylindrical structure. The inner cavity shape of the cylindrical structure is adapted to the outer contour shape of the pipe. The top heating end is located at the top abutment seat corresponding to the through hole, and the axis of the top heating end coincides with the axis of the through hole. Both the top heating end and the bottom heating end are electric heating elements.

8. The assembly and welding device for reactor pressure vessel nozzles and shell according to claim 1, characterized in that: The heating device on the outside of the bottom pipe includes at least two arc-shaped heating ends and at least two movable supports. The bottom of the movable supports is provided with wheels. Each movable support is provided with at least one arc-shaped heating end. The arc-shaped heating end is a gas heating device and has an arc-shaped heating surface that is adapted to the outer contour shape of the pipe. The at least two movable supports are configured to perform relative opening and closing movements to drive their respective corresponding arc-shaped heating ends to move closer or further apart; when the arc-shaped heating ends move closer to each other to the working position, the arc-shaped heating ends approach the outer contour of the pipe from multiple circumferential sides of the pipe below the cylinder to be welded, thereby heating and insulating the outer surface of the pipe.

9. The assembly and welding device for the reactor pressure vessel nozzle and shell according to claim 1, characterized in that: It also includes a top working platform and a bottom working platform. The top working platform is positioned above the cylinder to be welded and contacts the outer surface of the cylinder to be welded. The position of the top working platform corresponds to the position of the connecting pipe, and the shape of the bottom wall of the top working platform corresponds to the outline of the outer surface of the cylinder to be welded. The bottom working platform is set inside the cylinder to be welded and located below the mobile working mechanism, and the shape of the bottom wall of the bottom working platform corresponds to the shape of the inner wall of the cylinder to be welded.

10. A method for assembling and welding a reactor pressure vessel nozzle to its shell, characterized in that, Includes the following steps: S1: Fix the fixed base, level the adjustment platform through the second adjustment column, and put the telescopic rail in the storage state; set up the mobile working mechanism on the adjustment platform; hoist the cylinder to be welded onto the roller group, adjust the roller group to support the cylinder to be welded and enable it to rotate around its own axis, rotate the cylinder to be welded so that the top pipe installation position and the bottom pipe installation position are respectively above and below in the vertical direction. S2: Pull the telescopic rail out of the adjustment platform and connect it to the first adjustment column and fasten it. Level the telescopic rail through the first adjustment column and move the working mechanism back and forth along the telescopic rail to verify the work station. S3: Hoist the top working platform so that it comes into contact with the outer surface of the cylinder to be welded; The first connecting pipe is hoisted and positioned at the pipe installation location above the cylinder to be welded; the mobile working mechanism moves along the telescopic rail to below the first connecting pipe, and the heating device at the bottom of the connecting pipe is raised and pressed against the bottom of the first connecting pipe for heating and heat preservation via the lifting platform; the outer heating device of the top connecting pipe is hoisted and placed over the first connecting pipe to heat and preserve the outer surface of the first connecting pipe; the automatic welding machine is hoisted and fixed on the first connecting pipe; after preheating to the required temperature and achieving uniform temperature, the outer weld of the first connecting pipe is welded using the automatic welding machine; S4: After the outer side of the first connecting pipe is welded, remove the outer heating device of the top connecting pipe, the top working platform and the automatic welding machine; rotate the cylinder to be welded by 180° using the roller group so that the first connecting pipe is turned to the bottom. At this time, the welding position that was originally located below the vertical direction of the cylinder to be welded is now above the vertical direction. Move and close the arc-shaped heating ends of the heating device on the outside of the bottom pipe to the outer surface of the first pipe to heat and keep the first pipe warm; the mobile working mechanism uses its lifting device to hoist the bottom working platform into the inside of the cylinder to be welded and support it on the inner wall of the cylinder, and then hoist the root cleaning machine to clean the root of the outer weld of the first pipe under the heat preservation condition; after the root cleaning is completed, remove the root cleaning machine, and then hoist the automatic welding machine to weld the inner weld of the first pipe under the same heat preservation condition. S5: While performing step S4 to clean the root of the weld on the outside of the first pipe and weld the inside, perform the welding operation on the outside of the pipe in step S3 on the second pipe. S6: After completing the welding of the outer side of the second nozzle, the root cleaning of the outer weld of the first nozzle, and the welding of the inner side of the first nozzle, remove the heating device on the outer side of the top nozzle, the top working platform, the automatic welding machine on the outer side of the cylinder, and the bottom working platform, the root cleaning machine, and the automatic welding machine on the inner side of the cylinder; rotate the cylinder to be welded 180° again, so that the second nozzle is at the bottom and the first nozzle is at the top; move and close the arc-shaped heating ends of the heating device on the outer side of the bottom nozzle to the outer surface of the second nozzle for heating and heat preservation; move the working mechanism to hoist the bottom working platform and hoist the root cleaning machine and the automatic welding machine in sequence to complete the root cleaning of the outer weld and the welding of the inner side of the second nozzle respectively; while the second nozzle is being cleaned of the outer weld and welded on the inner side, hoist the heating device on the outer side of the top nozzle and cover the first nozzle to heat and preserve the outer surface of the first nozzle; S7: After all welding is completed, remove all heating devices, work platforms and automatic welding machines; move the working mechanism back to the adjustment platform along the telescopic rail, and retract the telescopic rail into the storage tank; lift the cylinder to be welded away and perform overall stress relief heat treatment.

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