Large-pipe-diameter nickel base alloy composite pipe welding method and auxiliary device

Abstract

The invention discloses a large-pipe-diameter nickel base alloy composite pipe welding method and an auxiliary device.Each composite pipe comprises a composite layer and a base layer covering the composite layer in a sleeving manner, the welding method comprises the following steps that firstly, the to-be-welded ends of two sets of composite pipes are machined, X-shaped grooves are formed in the positions of the to-be-welded ends of the two sets of composite pipes, and the to-be-welded ends of the two sets of composite pipes are welded; then the X-shaped groove is polished through an auxiliary device; secondly, the two sets of composite pipes are assembled in a butt joint mode, and a base layer is welded according to the sequence of bottoming, filling and capping; and thirdly, the transition layer and the composite layer are sequentially welded according to the bottoming, filling and covering sequence. According to the method, the X-shaped groove is adopted, the double-face welding mode is adopted, argon gas back face protection is not used in the whole welding process, compared with a traditional welding method, the welding material cost is saved, the welding work efficiency is improved, a large amount of argon gas is saved, the welding steps are simplified, the welding material cost is low, the number of welding layers is small, the construction period is shortened, and energy conservation and emission reduction are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of pipeline welding, and in particular to a welding method and an auxiliary device for a large-diameter nickel-based alloy composite pipe. Background Art

[0002] Traditional large-diameter nickel-based alloy composite pipe welding usually adopts traditional V-shaped groove and single-sided welding. The composite layer and transition layer are welded first, and then the base carbon steel part is welded. Nickel-based alloy welding materials must be used entirely. The inner composite layer is welded by manual tungsten inert gas arc welding, and then the transition layer and the base are welded by manual electrode arc welding. Stainless steel and nickel-based alloy welding wire electrodes are used in the transition layer between the composite layer and the base, as well as all layered welds of the base. However, since stainless steel and nickel-based alloy welding materials are relatively expensive, the above-mentioned welding method greatly increases the welding cost and has low welding efficiency. For this reason, we propose a large-diameter nickel-based alloy composite pipe welding method and auxiliary device. Summary of the invention

[0003] The purpose of the present invention is to provide a large-diameter nickel-based alloy composite pipe welding method and an auxiliary device to solve the problems of high welding cost and low welding efficiency of the existing composite pipe welding method mentioned in the above background technology.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] A large-diameter nickel-based alloy composite pipe welding method, the large-diameter nickel-based alloy composite pipe comprising: a composite layer and a base layer sheathed and coated outside the composite layer, the welding method comprising the following steps:

[0006] Step 1: Process the ends of two sets of large-diameter nickel-based alloy composite pipes to be welded so that an X-shaped groove is formed at the ends to be welded, and then the X-shaped groove is polished by an auxiliary device;

[0007] Step 2: Assemble two groups of large-diameter nickel-based alloy composite pipes in a butt-jointed manner, control the gap between the two groups, and weld the base layer in the order of base, filling, and covering;

[0008] Step 3: Then weld the transition layer and the composite layer in the order of base, filling and covering;

[0009] Among them, the X-shaped groove is formed in the entire circumferential direction of the ends of two groups of large-diameter nickel-based alloy composite pipes, and the X-shaped groove includes an upper funnel mouth, a lower funnel mouth and a transition section. The upper funnel mouth is formed upright on the base layer in the radial direction, and the lower funnel mouth is formed inverted in the radial direction on the base layer and the composite layer and close to a part of the composite layer, and the transition section connects the upper funnel mouth and the lower funnel mouth.

[0010] Compared with the prior art, the present invention has the following beneficial effects:

[0011] 1) The present invention adopts an X-shaped groove and a double-sided welding method. The base layer is first welded with a carbon steel welding wire rod, and then the transition layer and the composite layer are welded in sequence with a nickel-based alloy welding wire. The entire welding process does not use argon back protection. Compared with the traditional welding method, it saves welding material costs, improves welding work efficiency, saves a lot of argon gas, simplifies welding steps, and the base layer is welded with ordinary carbon steel, which has low welding material costs and a small number of welding layers, which not only shortens the construction period, but also saves energy and reduces emissions, and achieves good economic and social benefits;

[0012] 2) The present invention is also provided with an auxiliary device. After the X-shaped groove is opened in the large-diameter nickel-based alloy composite pipe, the auxiliary device grinds each slope of the X-shaped groove to remove burrs and impurities on the slope of the X-shaped groove, thereby ensuring the welding quality of the large-diameter nickel-based alloy composite pipe and further improving the welding efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of an X-shaped groove in the welding method of the present invention;

[0014] Figure 2 It is a schematic diagram of a pair of two-diameter nickel-based alloy composite pipes of the present invention;

[0015] Figure 3 It is a schematic diagram of the structure of the auxiliary device of the present invention;

[0016] Figure 4 It is a schematic diagram of the locking member structure of the present invention;

[0017] Figure 5 It is a schematic diagram of the contact between the grinding column and the transition section of the present invention;

[0018] Figure 6 It is a schematic diagram of the contact between the grinding column and the slope surface of the present invention.

[0019] In the figure: 100, base layer; 200, composite layer; 300, upper funnel mouth; 301, slope surface 1; 400, transition section; 401, slope surface 2; 500, lower funnel mouth; 501, slope surface 3; 600, positioning part; 601, base; 602, pipe clamping mechanism; 603, bidirectional screw; 604, rotating device 1; 700, processing part; 701, sleeve; 702, guide seat; 703, arc guide groove 1; 704, rotating device 2; 705, telescopic device 2; 706, arc guide groove 2; 707, fixed block; 708, grinding column; 709, rotating sleeve; 710, elastic member; 711, electromagnetic member; 712, pressure block; 713, diverter; 714, nozzle; 715, telescopic device 3; 716, bearing seat; 717, gear set; 718, rotating device 3; 719, telescopic device 4; 720, baffle. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] Please see attached Figure 1 -Attached Figure 2

[0022] A large-diameter nickel-based alloy composite pipe welding method, the large-diameter nickel-based alloy composite pipe comprises: a composite layer 200 and a base layer 100 wrapped outside the composite layer 200, the base layer 100 is ASTM A106, that is, a carbon steel layer, and the composite layer 200 is Incoloy825;

[0023] The welding method comprises the following steps:

[0024] Step 1: machining the ends of two sets of large-diameter nickel-based alloy composite pipes to be welded so that an X-shaped groove is formed at the joint ends, and then the X-shaped groove is polished by an auxiliary device, so that the X-shaped groove is conducive to the welding of the large-diameter nickel-based alloy composite pipes;

[0025] Preferably, an X-shaped groove is adopted, the angle of the groove c on the side of the base layer 100 is 60°-70°, the angle of the groove on the side of the composite layer 200 is 50°-60°, the root gap a is 2.8mm-4mm, the blunt edge length b is 1mm-3mm, and the distance from the root of the groove of the base layer 100 to the bonding surface of the base layer 100 and the composite layer 200 is ≤4mm; the depth of the composite layer 200 side of the X-shaped groove is the thickness of the composite layer 200 + 5mm, and the depth of the base layer 100 side is the thickness of the base layer 100 - 5mm - the blunt edge thickness;

[0026] Step 2: Assemble two groups of large-diameter nickel-based alloy composite pipes in a butt-jointed manner, control the gap between the two groups, and weld the base layer 100 in the order of base, filling, and capping;

[0027] Step 3: Then weld the transition layer and the composite layer 200 in the order of base, filling and covering;

[0028] The X-shaped groove is formed in the entire circumferential direction of the ends of the two sets of large-diameter nickel-based alloy composite pipes. The X-shaped groove includes an upper funnel 300, a lower funnel 500 and a transition section 400. Figure 3It can be seen that the upper funnel mouth 300 has a slope 1 301 with an inclined vertical section, and the lower funnel mouth 500 has a slope 3 501 with an inclined vertical section. The slope 1 301 and the slope 3 501 have opposite inclination angles, and the transition section 400 has a slope 2 401 with a vertical section. It should be noted that the slope 1 301, the slope 2 401 and the slope 3 501 are all radially arranged at the end of the large-diameter nickel-based alloy composite pipe;

[0029] The upper funnel mouth 300 is formed upright on the base layer 100 in the radial direction, the lower funnel mouth 500 is formed inverted on the base layer 100 and the composite layer 200 and close to a portion of the composite layer 200 in the radial direction, and the transition section 400 connects the upper funnel mouth 300 and the lower funnel mouth 500, and the transition section 400 has an equal aperture in the radial direction.

[0030] As a preferred embodiment, the present embodiment adopts a double-sided welding method, firstly using a carbon steel welding wire electrode to weld the base layer 100, and then using a nickel-based alloy welding wire electrode to weld the transition layer and the composite layer 200 in sequence; wherein,

[0031] The thickness of the base layer 100 is 8.98 mm to 47 mm, and the thickness of the composite layer 200 is 3 mm to 5 mm.

[0032] Preferably, the welds on the base layer 100 side and the composite layer 200 side of the present embodiment are welded in layers and passes, and the pass welding is a transverse oscillating weld pass with an oscillation amplitude less than 3 times the diameter of the welding wire or electrode.

[0033] Preferably, during the welding process, the interlayer temperature on the base layer 100 side is ≤250°C, and the interlayer temperature on the composite layer 200 side is ≤100°C.

[0034] This implementation adopts 5G butt weld, which is horizontal fixed welding, and the welding direction is from bottom to top, specifically:

[0035] In step 2, the number of welding passes on the base layer 100 side is determined according to the specific thickness of the carbon steel layer, as long as the width of each pass of each layer does not exceed 3 times the diameter of the selected welding material;

[0036] The first and second layers of the welding layer on the side of the X-shaped groove base 100 are welded by manual tungsten inert gas arc welding, the welding material is welding wire E70S-2, specification is φ2.4, welding current is 90-120A, welding voltage is 10-14V, welding speed is 70-100mm / min; the other layers of filling and covering are filled with welding rods with specification of φ3.2, welding rods are E7018, welding current is 90-130A, welding voltage is 22-26V, welding speed is 88-138mm / min;

[0037] In step 3, the welding of the composite side is divided into 4 layers and 7 passes, and all passes are welded by manual argon arc welding. The welding material is ERNiCrMo-3, the specification is φ2.4, the welding current is 110-130A, the welding voltage is 9-12V, and the welding speed is 70-100mm / min;

[0038] Among them, when the diameter of the welded composite pipe is large or the composite plate is welded, the first and second layers can be welded by manual tungsten inert gas arc welding, and the other layers are welded by manual arc welding. The welding rod is ENiCrMo-3, the welding current is 90-110A, the welding voltage is 22-26V, and the welding speed is 88-118mm / min;

[0039] The tungsten shielding gas for manual tungsten inert gas welding is 99.99% argon with a flow rate of 12L / min; the nozzle diameter is 10mm and the extension length is 5mm; the ENiCrMo-3 welding rod does not need to be baked when it is taken out of the vacuum packaging box for the first time. If it is not used up within the specified time, it needs to be baked. The baking temperature is 200-250℃, the baking time is 1 hour, and the insulation is 120℃; the baking temperature of the E7018 welding rod is 350℃, the baking time is 1 hour, and the insulation is 150℃.

[0040] It should be noted that carbon steel can be used for interlayer grinding and cleaning on the side of the base layer 100; stainless steel must be used for interlayer grinding and cleaning on the side of the composite layer 200. During welding, according to the thickness of the base layer 100 and the composite layer 200, welding is performed in sequence according to the process parameters and sequence of the present invention until the X-shaped groove is filled. The smaller the thickness of the base layer 100 and the composite layer 200, the fewer the number of weld passes required for the weld layer, and the larger the thickness of the base layer 100 and the composite layer 200, the more the number of weld passes required for the weld layer.

[0041] Please see attached Figure 3 -Attached Figure 6

[0042] An auxiliary device for welding a large-diameter nickel-based alloy composite pipe is applied to the above-mentioned welding method, and the auxiliary device comprises:

[0043] The positioning part 600 is used to position two groups of large-diameter nickel-based alloy composite pipes to be processed; and

[0044] The processing part 700 is disposed on the positioning part 600 and is used to grind the X-shaped grooves formed at opposite ends of two groups of large-diameter nickel-based alloy composite pipes to remove burrs at the X-shaped grooves.

[0045] Preferably, the positioning portion 600 of this embodiment includes:

[0046] A base 601, on which two groups of support seats are slidably arranged, and the two groups of support seats are respectively threadedly sleeved on the two ends of the outer wall of the bidirectional lead screw 603, and the bidirectional lead screw 603 is rotatably arranged in the base 601, and one end of the bidirectional lead screw 603 is connected to the output end of a rotating device 604 arranged on the base 601, and the rotating device 604 is a servo motor and a reducer, and the bidirectional lead screw 603 is driven to rotate by the rotating device 604 to drive the two groups of support seats to move closer to or away from each other, thereby adjusting the distance between the two groups of large-diameter nickel-based alloy composite pipes; and

[0047] Two sets of pipe clamping mechanisms 602 are respectively arranged on two sets of support seats, and are used to fix two sets of large-diameter nickel-based alloy composite pipes to be processed. The pipe clamping mechanism 602 belongs to a conventional mechanism in this field. The pipe clamping mechanism 602 is, for example, a pipe clamper or a pipe clamping robot.

[0048] Preferably, the processing unit 700 of this embodiment includes:

[0049] The sleeve 701 is sleeved on the outer sides of opposite ends of the two sets of large-diameter nickel-based alloy composite pipes. The sleeve 701 is coaxial with the pipe clamping mechanism 602. The diameter of the sleeve 701 is larger than the outer diameter of the large-diameter nickel-based alloy composite pipes.

[0050] At least two sets of bearing seats 716 are respectively sleeved on the outer walls of both sides of the sleeve 701. The bottoms of the at least two sets of bearing seats 716 are connected to the base 601 through brackets. The sleeve 701 can rotate but will not move horizontally along its axis through the bearing seats 716.

[0051] The rotating device 3 718 is arranged on the bracket. The output end of the rotating device 3 718 is connected to the sleeve 701 through the gear set 717. The gear set 717 is two sets of meshing gears. The rotating device 3 718 is a servo motor and a reducer. The sleeve 701 can rotate relative to the large-diameter nickel-based alloy composite pipe clamped by the pipe clamping mechanism 602 through the rotating device 3 718 and the gear set 717.

[0052] Two sets of grinding pieces are symmetrically arranged on the inner wall of the sleeve 701, and the grinding pieces include:

[0053] The guide seat 702 is arranged on the inner wall of the sleeve 701. The guide seat 702 is provided with an arc-shaped guide groove 1 703 and an arc-shaped guide groove 2 706. One end of the arc-shaped guide groove 1 703 is connected to one end of the arc-shaped guide groove 2 706. The arc-shaped guide groove 1 703 is connected with a rotating device 2 704 through a sliding member. The sliding member is, for example, a roller. The output end of the rotating device 2 704 is detachably provided with a grinding column 708. The rotating device 2 704 is a grinding motor; and,

[0054] The fixing block 707 is in the shape of a disc, and is provided with a through hole for the grinding column 708 to penetrate therethrough. A locking piece fixed to the outer wall of the grinding column 708 is provided in the through hole, so that the fixing block 707 is fixed at a designated position of the outer wall of the grinding column 708, specifically, fixed at the lower end of the outer wall of the grinding column 708 or fixed at the upper end of the outer wall of the grinding column 708;

[0055] The fixed block 707 is arranged at the output end of the rotating device 4 (not shown in the figure), and the rotating device 4 is connected to one end of the telescopic device 2 705 arranged on the sleeve 701. The telescopic device 2 705 can be an electric telescopic device. The telescopic device 2 705 is used to drive the fixed block 707 to move to the lower end or the upper end of the outer wall of the grinding column 708;

[0056] As attached Figure 4 As shown, when the fixed block 707 is at the lower end of the outer wall of the grinding column 708, the sliding member is at one end of the arc-shaped guide groove 1 703. At this time, the axis of the grinding column 708 is parallel to the inner wall of the lower funnel mouth 500, that is, the grinding column 708 is in contact with the outer wall of the slope surface 3 501 of the lower funnel mouth 500. The large-diameter nickel-based alloy composite pipe is moved by the positioning part 600 until the slope surface 3 501 is in contact with the grinding column 708. The grinding column 708 is driven to rotate by opening the rotating device 2 704, and the rotating device 3 718 is opened to rotate the sleeve 701 360 degrees. In this way, the slope surface 3 501 area can be polished;

[0057] When the fixing block 707 is at the upper end of the outer wall of the grinding column 708, if the Figure 5 -Attached Figure 6 In the state shown, the rotating device 4 drives the fixed block 707 to drive the grinding column 708 so that the sliding part is at the other end of the arc-shaped guide groove 1 703. At this time, the axis of the grinding column 708 is parallel to the inner wall of the transition section 400, that is, the grinding column 708 contacts the outer wall of the slope 2 401 of the transition section 400. The large-diameter nickel-based alloy composite pipe is moved by the positioning part 600 until the slope 2 401 contacts the grinding column 708. The grinding column 708 is driven to rotate by opening the rotating device 2 704, and the rotating device 3 718 is opened to rotate the sleeve 701 360 degrees. In this way, the slope 2 401 area can be polished; and,

[0058] When the fixed block 707 is at the upper end of the outer wall of the grinding column 708, the four-wheel drive of the rotating device drives the fixed block 707 to drive the grinding column 708 so that the sliding part moves from the arc guide groove 1 703 to one end of the arc guide groove 2 706. At this time, the axis of the grinding column 708 is parallel to the inner wall of the upper funnel mouth 300, that is, the grinding column 708 contacts the outer wall of the slope 1 301 of the upper funnel mouth 300, and the large-diameter nickel-based alloy composite pipe is moved through the positioning part 600 until the slope 1 301 contacts the grinding column 708. The grinding column 708 is driven to rotate by opening the rotating device 2 704, and the rotating device 3 718 is opened at the same time to rotate the sleeve 701 360 degrees. In this way, the slope 1 301 area can be polished.

[0059] Preferably, the locking member of this embodiment includes:

[0060] The rotating sleeve 709 is rotatably sleeved on the inner wall of the through hole through a bearing and movably sleeved on the outer wall of the grinding column 708. The circumferential outer wall of the rotating sleeve 709 is provided with a plurality of openings so that the subsequent electromagnetic member 711 can transmit magnetic force to the pressing block 712 when it is energized;

[0061] A plurality of pressing blocks 712 are intermittently arranged in a circular array in the rotating sleeve 709 for contacting the outer wall of the grinding column 708. A rubber layer may be provided on the side of the pressing block 712 contacting the grinding column 708 to increase the friction between the two. The pressing block 712 is a magnetic pressing block. The pressing block 712 is connected to the inner wall of the rotating sleeve 709 through an elastic member 710. The elastic member 710 is, for example, a spring-like structure. And,

[0062] The electromagnetic member 711 is annular and embedded in the inner wall of the rotating sleeve 709 and corresponds to the through hole. It is used to drive the pressing block 712 to contact the outer wall of the grinding column 708 when it is energized. The electromagnetic member 711 generates the same magnetic pole as the pressing block 712 when it is energized. Under the repulsive force of the same poles, the pressing block 712 is closely attached to the grinding column 708. At this time, the fixed block 707 is fixed to the outer wall of the grinding column 708. Moreover, because the electromagnetic member 711 is annular, when the grinding column 708 rotates, the pressing block 712 drives the rotating sleeve 709 to rotate relative to the fixed block 707, which will not affect the rotation of the grinding column 708.

[0063] In this way, when the rotating device 4 drives the fixed block 707, the fixed block 707 can drive the grinding column 708 to rotate, and when the telescopic device 2 705 drives the fixed block 707 to move, the electromagnetic component 711 can be powered off, thereby changing the position of the fixed block 707 on the outer wall of the grinding column 708, and then changing the rotation fulcrum of the grinding column 708. It should be noted that the fixed block 707 is at the lower end of the outer wall of the grinding column 708, and at this time, the output end of the rotating device 4 and the arc guide groove 1 703 are on the same axis; the fixed block 707 is at the upper end of the outer wall of the grinding column 708, and at this time, the output end of the rotating device 4 and the arc guide groove 2 706 are on the same axis, and the length of the grinding column 708 is greater than the length of the slope 1 301, so that the grinding column 708 can grind the slope 1 301, the slope 2 401 and the slope 3 501 to remove the burrs on the outer wall of the X-shaped groove.

[0064] Preferably, the processing unit 700 of this embodiment further includes:

[0065] The flow divider 713 is disposed in the sleeve 701 and between the two groups of grinding members. One end of the flow divider 713 is connected to a device for supplying cleaning liquid from the outside through a pipeline. The device for supplying cleaning liquid from the outside belongs to conventional equipment in the art and will not be described in detail herein; and

[0066] Two groups of nozzles 714 are symmetrically arranged on both sides of the diverter 713 and correspond to the two groups of grinding parts respectively. The nozzles 714 are connected to the diverter 713 through pipelines. The nozzles 714 are connected to the telescopic device three 715 arranged on the outer wall of the diverter 713. The telescopic device three 715 is, for example, an electric telescopic device. The position of the nozzles 714 can be adjusted by the telescopic device three 715 so that the nozzles 714 correspond to the slope surface one 301, the slope surface two 401 and the slope surface three 501 respectively. The cleaning liquid sprayed by the nozzles 714 can clean the outer wall of the X-shaped groove, thereby improving the cleaning quality of the X-shaped groove.

[0067] As a preferred embodiment, baffles 720 are symmetrically slidably provided on the upper and lower sides of both ends of the sleeve 701 of this embodiment. The width of the baffle 720 is greater than or equal to the outer diameter of the sleeve 701. The opposite ends of the upper and lower baffles 720 are provided with arc grooves that match the large-diameter nickel-based alloy composite tube. A sealing ring can be embedded in the inner wall of the arc groove to ensure the sealing between the baffle 720 and the large-diameter nickel-based alloy composite tube to avoid damage to the outer wall of the large-diameter nickel-based alloy composite tube by the baffle 720. The upper and lower baffles 720 are also respectively extended and retracted. Device four 719 is connected to the outer wall of the sleeve 701. The baffle 720 is driven to contact the outer wall of the large-diameter nickel-based alloy composite pipe by telescopic device four 719, so as to prevent the cleaning liquid in the sleeve 701 from leaking out of the sleeve 701. A drainage connecting pipe is provided on the lower baffle 720. After the X-shaped groove of the large-diameter nickel-based alloy composite pipe is processed, a pumping device can be connected to the drainage connecting pipe to extract the cleaning liquid in the sleeve 701. It should be noted that when extracting the cleaning liquid, it is necessary to ensure that the drainage connecting pipe is located at the lower end of the sleeve 701.

[0068] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A large-diameter nickel-based alloy composite pipe welding method, the large-diameter nickel-based alloy composite pipe comprising: A composite layer (200) and a base layer (100) wrapped around the composite layer (200), characterized in that the welding method comprises the following steps: Step 1: Process the ends of two sets of large-diameter nickel-based alloy composite pipes to be welded so that an X-shaped groove is formed at the ends to be welded, and then the X-shaped groove is polished by an auxiliary device; Step 2: align two groups of large-diameter nickel-based alloy composite pipes in a butt-jointed manner, control the aligning gap, and then weld the base layer in the order of base, filling, and capping (100); Step 3: Then, the transition layer and the composite layer (200) are welded in the order of base, filling, and covering; The X-shaped groove is formed in the entire circumferential direction of the ends of two groups of large-diameter nickel-based alloy composite pipes, and the X-shaped groove includes an upper funnel (300), a lower funnel (500) and a transition section (400). The upper funnel (300) is formed upright on the base layer (100) in the radial direction, and the lower funnel (500) is formed inverted on the base layer (100) and the composite layer (200) in the radial direction and close to a part of the composite layer (200). The transition section (400) connects the upper funnel (300) and the lower funnel (500).

2. The welding method according to claim 1, characterized in that: A double-sided welding method is adopted, wherein a carbon steel welding wire electrode is used to weld a base layer (100), and then a nickel-based alloy welding wire electrode is used to weld a transition layer and a composite layer (200) in sequence; wherein, The thickness of the base layer (100) is 8.98 mm to 47 mm, and the thickness of the composite layer (200) is 3 mm to 5 mm.

3. The welding method according to claim 1, characterized in that: The weld seams on the base layer (100) side and the composite layer (200) side are welded in layers and passes. The pass welding is a transverse swing weld pass, and the swing amplitude is less than 3 times the diameter of the welding wire and the welding rod.

4. The welding method according to claim 3, characterized in that: In the second step, the first and second layers of the welding layer on the side of the X-shaped groove base layer (100) are welded by manual tungsten inert gas arc welding, the welding material is E70S-2 welding wire, the specification is φ2.4, the welding current is 90-120A, the welding voltage is 10-14V, and the welding speed is 70-100mm / min. The remaining layers are filled and covered with welding rods with a specification of φ3.2, the welding rod is E7018, the welding current is 90-130A, the welding voltage is 22-26V, and the welding speed is 88-138mm / min; In the step 3, the X-shaped groove cladding (200) side is welded by manual tungsten inert gas arc welding, the welding material is ERNiCrMo-3 welding wire, the specification is φ2.4, the welding current is 110-130A, the welding voltage is 9-12V, and the welding speed is 70-100mm / min.

5. An auxiliary device for welding a large-diameter nickel-based alloy composite pipe, applied to the welding method according to any one of claims 1 to 4, characterized in that: The auxiliary device includes: A positioning portion (600) is used to position two groups of large-diameter nickel-based alloy composite pipes to be processed; and The processing part (700) is arranged on the positioning part (600) and is used for grinding the X-shaped grooves formed at opposite ends of two groups of large-diameter nickel-based alloy composite pipes.

6. The auxiliary device according to claim 5, characterized in that: The positioning portion (600) comprises: A base (601), wherein two groups of support seats are slidably arranged on the base (601), and the two groups of support seats are respectively threadedly sleeved on the two ends of the outer wall of the bidirectional lead screw (603), and the bidirectional lead screw (603) is rotatably arranged in the base (601), and one end of the bidirectional lead screw (603) is connected to the output end of a rotating device (604) arranged on the base (601); and Two sets of pipe clamping mechanisms (602) are respectively arranged on two sets of support seats and are used to fix two sets of large-diameter nickel-based alloy composite pipes to be processed.

7. The auxiliary device according to claim 5, characterized in that: The processing unit (700) comprises: A sleeve (701) is sleeved on the outer sides of opposite ends of two groups of large-diameter nickel-based alloy composite pipes, and the sleeve (701) is coaxial with the pipe clamping mechanism (602); At least two groups of bearing seats (716) are respectively sleeved on the outer walls of both sides of the sleeve (701), and the bottoms of at least two groups of bearing seats (716) are connected to the base (601) through brackets; A rotating device (718) is arranged on the bracket, and an output end of the rotating device (718) is transmission-connected to the sleeve (701) via a gear set (717); Two groups of grinding pieces are symmetrically arranged on the inner wall of the sleeve (701), and the grinding pieces include: A guide seat (702) is arranged on the inner wall of the sleeve (701), and an arc-shaped guide groove 1 (703) and an arc-shaped guide groove 2 (706) are provided on the guide seat (702), one end of the arc-shaped guide groove 1 (703) is connected to one end of the arc-shaped guide groove 2 (706), a rotating device 2 (704) is connected to the arc-shaped guide groove 1 (703) via a sliding member, and a grinding column (708) is detachably provided at the output end of the rotating device 2 (704); and, A fixed block (707) is provided with a through hole for the grinding column (708) to pass through, and a locking member fixed to the outer wall of the grinding column (708) is provided in the through hole. The fixed block (707) is provided at the output end of the rotating device 4, and the rotating device 4 is connected to one end of the telescopic device 2 (705) provided on the sleeve (701). The telescopic device 2 (705) is used to drive the fixed block (707) to move to the lower end or the upper end of the outer wall of the grinding column (708). When the fixed block (707) is at the lower end of the outer wall of the grinding column (708), the sliding member is at one end of the arc-shaped guide groove 1 (703). At this time, the axis of the grinding column (708) is The line is parallel to the inner wall of the lower funnel mouth (500); when the fixed block (707) is at the upper end of the outer wall of the grinding column (708), the four-wheel drive of the rotating device causes the fixed block (707) to drive the grinding column (708) so that the sliding part is at the other end of the arc-shaped guide groove 1 (703), and the axis of the grinding column (708) is parallel to the inner wall of the transition section (400), and the four-wheel drive of the rotating device causes the fixed block (707) to drive the grinding column (708) so that the sliding part moves from the arc-shaped guide groove 1 (703) to one end of the arc-shaped guide groove 2 (706), at which time the axis of the grinding column (708) is parallel to the inner wall of the upper funnel mouth (300).

8. The auxiliary device according to claim 7, characterized in that: The locking member comprises: A rotating sleeve (709) is arranged on the inner wall of the through hole and movably sleeved on the outer wall of the grinding column (708), and a plurality of through openings are opened on the circumferential outer wall of the rotating sleeve (709); A plurality of pressing blocks (712) are intermittently arranged in a circular array in the rotating sleeve (709) for contacting the outer wall of the grinding column (708), wherein the pressing blocks (712) are magnetic pressing blocks, and the pressing blocks (712) are connected to the inner wall of the rotating sleeve (709) through elastic members (710); and, The electromagnetic member (711) is annular and is embedded in the inner wall of the rotating sleeve (709) and corresponds to the through opening, and is used to drive the pressing block (712) to contact the outer wall of the grinding column (708) by power.

9. The auxiliary device according to claim 7, characterized in that: The processing unit (700) further includes: A flow divider (713) is disposed in the sleeve (701) and between the two groups of polishing members, one end of the flow divider (713) is connected to a device for supplying cleaning liquid from the outside through a pipeline; and Two groups of nozzles (714) are symmetrically arranged on both sides of the diverter (713) and correspond to the two groups of polishing parts respectively. The nozzles (714) are connected to the diverter (713) through pipelines. The nozzles (714) are connected to the telescopic device (715) arranged on the outer wall of the diverter (713).

10. The auxiliary device according to claim 9, characterized in that: Baffles (720) are symmetrically slidably provided on the upper and lower sides of both ends of the sleeve (701), and arc grooves matching with the large-diameter nickel-based alloy composite pipe are opened at the opposite ends of the upper and lower baffles (720). The upper and lower baffles (720) are also connected to the outer wall of the sleeve (701) through telescopic devices (719) respectively, and a drainage connection pipe is provided on the lower baffle (720).

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