High-performance welding method and device for thick-wall gas-electric vertical welding based on liquid nitrogen rapid cooling assistance

Abstract

The application belongs to the technical field of welding, and discloses a thick-wall gas-electric vertical welding high-performance welding method and device based on liquid nitrogen rapid cooling assistance. The method groups and pairs thick plates to be welded with a thickness greater than 30 mm to form a welding groove, and then adopts gas-electric vertical welding to weld the welding groove. In the welding process, the welding surface is locally rapidly cooled in a liquid nitrogen cooling mode, and the back of the welding surface is cooled in a water cooling mode, so as to improve the cooling speed of the heat affected zone of the welding joint under the assistance of liquid nitrogen rapid cooling. In the gas-electric vertical welding process, the application adopts the mode of liquid nitrogen cooling of the welding surface combined with water cooling of the back of the welding surface to cool, which can improve the cooling speed of the welding heat affected zone under the assistance of liquid nitrogen rapid cooling, and under the comprehensive action of the two, the cooling speed of the welding heat affected zone is accelerated to the greatest extent, the high-temperature residence time is reduced, and the width of the welding heat affected zone is reduced, so that the embrittlement problem of the coarse-grained heat affected zone of the welding joint is avoided, and the toughness of the welding joint is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of welding, and more particularly relates to a high-performance thick-wall electric-gas vertical welding method and device assisted by liquid nitrogen rapid cooling. BACKGROUND

[0002] In recent years, with the development of the exploitation of China's offshore oil and gas resources to harsh conditions such as low temperature and deep water, the thickness of offshore platform jacket steel is getting larger and larger, and higher requirements are put forward for the efficiency of welding and the quality of welded joints. At present, electric-gas vertical welding (EGW) as a high-efficiency large heat input welding technology is gradually replacing the traditional multi-pass welding process of thick plates. The maximum heat input of single-wire electric-gas vertical welding can reach 350kJ / cm, realizing single-pass forming of 40mm thick plates. In the face of larger plate thickness, the heat input of double-wire electric-gas vertical welding can reach 750kJ / cm, realizing single-pass forming of 85mm thick plates. However, excessive heat input will inevitably lead to the embrittlement of the heat affected zone, reducing the overall toughness of the welded joint.

[0003] To improve the toughness of the welded joint, CN116890180A discloses a high-strength steel thick plate welded joint groove and double-wire electric-gas vertical welding method. This method reduces the cross-sectional area of the groove by reducing the angle of the groove, thereby weakening the heat input of electric-gas vertical welding. However, the reduction of the groove angle is limited by the space of the welding gun swing range, and when the plate thickness becomes larger and larger, the heat input will increase rapidly. CN217832376U discloses a device for increasing the cooling effect of electric-gas vertical welding water-cooled sliding block. This device increases the cooling effect by setting a water-cooled sliding block device. However, the main function of the sliding block is to force the formation of the welded joint, and the main function of the water cooling is to prevent the melting of the sliding block. Moreover, it can only take away part of the heat from the welded joint area and cannot cool the heat affected zone. Therefore, electric-gas vertical welding is currently mainly used in some occasions where performance requirements are not high. In the face of harsh low-temperature marine environments, the embrittlement problem of the coarse-grained heat affected zone of the welded joint has seriously restricted its application. SUMMARY

[0004] In view of the defects of the prior art, the application provides a high-performance thick-wall electric-gas vertical welding method and device assisted by liquid nitrogen rapid cooling, aiming to solve the problem of excessive heat input of existing electric-gas vertical welding, which leads to poor toughness of the welded joint.

[0005] According to an aspect of the present application, a high-performance welding method based on liquid nitrogen rapid cooling assisted thick-wall gas-electric vertical welding is provided, specifically: a thick plate to be welded with a thickness greater than 30 mm is matched to form a welding groove, and then the welding groove is welded by gas-electric vertical welding. During the welding process, the welding surface is locally rapidly cooled by liquid nitrogen cooling, and the back of the welding surface is cooled by water cooling, thereby increasing the cooling speed of the heat affected zone of the welded joint under the assistance of liquid nitrogen rapid cooling.

[0006] Compared with the prior art, the above technical scheme conceived by the present application can effectively improve the cooling speed of the heat affected zone of the welded joint by locally rapidly cooling the welded joint of the welding surface by liquid nitrogen cooling, thereby avoiding the embrittlement problem of the coarse-grained heat affected zone of the welded joint.

[0007] As a further preferred, when the wall thickness of the thick plate to be welded is less than 50 mm, the welding groove is a single V-shaped groove, and the back of the welding surface is cooled by indirect water cooling; when the wall thickness of the thick plate to be welded is greater than or equal to 50 mm, the welding groove is an X-shaped groove, and when welding the first surface, the back of the welding surface is cooled by direct water cooling, and when welding the other surface, the back of the welding surface is cooled by indirect water cooling.

[0008] As a further preferred, the flow rate of the liquid nitrogen is 0.1 L / min to 0.2 L / min.

[0009] According to another aspect of the present application, a high-performance welding device based on liquid nitrogen rapid cooling assisted thick-wall gas-electric vertical welding is provided for performing the above method, which comprises a welding gun, a back water cooling assembly and a front water cooling assembly. The welding gun is used to weld the welding groove by gas-electric vertical welding. The back water cooling assembly is arranged on the back of the welding surface of the thick plate to be welded and is used to water cool the back of the welding surface. The front water cooling assembly is arranged on the welding surface of the thick plate to be welded and moves with the welding gun. The front water cooling assembly comprises a water cooling slide and a protective gas channel, a cooling water channel and a liquid nitrogen injection channel arranged inside the water cooling slide. The protective gas channel is used to provide protective gas during welding. The cooling water channel is used to pass cooling water to cool the water cooling slide to prevent it from melting to force the weld to form. The liquid nitrogen injection channel is used to inject liquid nitrogen into the welded joint during welding to achieve local rapid cooling of the heat affected zone of the welded joint.

[0010] As a further preferred, the protective gas channel is arranged at the center of the water cooling slide, the first water inlet and the first water outlet of the cooling water channel are arranged on both sides of the protective gas channel respectively, and the liquid nitrogen injection channel is two, arranged on both sides of the first water inlet and the first water outlet respectively.

[0011] As a further preferred, the inner part of the two liquid nitrogen injection channels is respectively fixed with a first liquid nitrogen injector and a second liquid nitrogen injector, the center line of the first liquid nitrogen injector and the second liquid nitrogen injector is respectively 1mm-2mm away from the outside of the weld fusion line, and the end of the first liquid nitrogen injector and the second liquid nitrogen injector is 1mm-3mm away from the welding surface of the thick plate to be welded.

[0012] As a further preferred, when the wall thickness of the thick plate to be welded is less than 50mm, the back water cooling assembly comprises a back water cooling pad and a water cooling pipeline arranged inside the back water cooling pad, the back water cooling pad is arranged at the root of the welding groove of the thick plate to be welded along the length direction of the thick plate to be welded and is tightly attached to the thick plate to be welded, and the water cooling pipeline is distributed in a serpentine shape inside the back water cooling pad.

[0013] As a further preferred, the water inlet of the water cooling pipeline is arranged at the bottom of the back water cooling pad, and the water outlet of the water cooling pipeline is arranged at the top of the back water cooling pad.

[0014] As a further preferred, the width of the back water cooling pad is more than 3 times the maximum groove width of the welding groove.

[0015] As a further preferred, when the wall thickness of the thick plate to be welded is greater than or equal to 50mm, the back water cooling assembly comprises a cooling water pipeline for spraying water to the root of the welding groove of the thick plate to be welded, and the cooling water pipeline is synchronously moved with the front water cooling assembly during welding when welding one side; and the back water cooling assembly comprises a back water cooling pad and a water cooling pipeline arranged inside the back water cooling pad when welding the other side, the back water cooling pad is arranged at the root of the welding groove of the thick plate to be welded along the length direction of the thick plate to be welded and is tightly attached to the thick plate to be welded, and the water cooling pipeline is distributed in a serpentine shape inside the back water cooling pad.

[0016] Overall, compared with the prior art, the above technical solutions conceived by the present application mainly have the following technical advantages:

[0017] 1. In the process of gas-electric vertical welding, the present application adopts the method of welding surface liquid nitrogen cooling combined with welding surface back water cooling for cooling, which can improve the cooling speed of the welding heat affected zone under the assistance of liquid nitrogen fast cooling, and under the comprehensive action of the two, the cooling speed of the welding heat affected zone is maximized, the high-temperature residence time is reduced, and the width of the welding heat affected zone is reduced, thereby avoiding the embrittlement problem of the coarse-grained heat affected zone of the welded joint, improving the toughness of the welded joint, and making it more suitable for the low-temperature marine environment with strict requirements.

[0018] 2. At the same time, the present application optimizes the shape of the groove and the specific way of welding surface back water cooling according to the wall thickness, which can further improve the cooling speed, thereby further improving the toughness of the welded joint. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is a top view of a high-performance welding process of a 40mm thick plate assisted by liquid nitrogen rapid cooling of thick-wall gas-electric vertical welding provided in Embodiment 1 of the present application;

[0020] Figure 2 is a bevel cross-sectional view of a high-performance welding process of a 40mm thick plate assisted by liquid nitrogen rapid cooling of thick-wall gas-electric vertical welding provided in Embodiment 1 of the present application;

[0021] Figure 3 is a top view of a high-performance welding process of an 80mm thick plate assisted by liquid nitrogen rapid cooling of thick-wall gas-electric vertical welding provided in Embodiment 2 of the present application;

[0022] Figure 4 is a bevel cross-sectional view of a high-performance welding process of an 80mm thick plate assisted by liquid nitrogen rapid cooling of thick-wall gas-electric vertical welding provided in Embodiment 1 of the present application;

[0023] Figure 5 is a CTOD test curve of a welded joint and a non-cooling welded joint in Embodiment 1 of the present application;

[0024] Figure 6 is a CTOD test curve of a welded joint and a non-cooling welded joint in Embodiment 2 of the present application.

[0025] In all the drawings, the same reference signs are used to represent the same elements or structures, wherein:

[0026] 1-thick plate to be welded, 2-back water cooling pad, 3-water cooling pipe, 4-water cooling slide, 5-first liquid nitrogen sprayer, 6-first water inlet, 7-protective gas channel, 8-first water outlet, 9-second liquid nitrogen sprayer, 10-second water inlet, 11-second water outlet, 12-cooling water channel, 13-liquid nitrogen spraying channel, 14-liquid nitrogen, 15-cooling water pipe, 16-cooling water, 17-welding torch. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solutions and advantages of the present application more clear, the present application is further described in detail below in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0028] As shown in Figures 1-4 , the present application provides a high-performance welding method of thick-wall gas-electric vertical welding assisted by liquid nitrogen rapid cooling, specifically: a thick plate to be welded 1 with a thickness greater than 30mm is matched to form a welding bevel, the welding bevel preferably adopts a single-sided V-shaped bevel or an X-shaped bevel, and then the welding bevel is welded by gas-electric vertical welding;

[0029] During the welding process, the welding surface of the thick plate to be welded 1 is locally rapidly cooled by liquid nitrogen cooling, liquid nitrogen has the advantages of fast cooling speed and can quickly absorb a large amount of heat, quickly take away the heat of the welded joint area, thereby realizing the rapid cooling of the heat affected zone, avoiding the embrittlement problem of the coarse grain heat affected zone of the welded joint, and further making the welded product more suitable for the harsh low-temperature marine environment, and the liquid nitrogen also has the advantage of no residual pollution, which will not adversely affect the welded joint.

[0030] At the same time, the back of the welding surface of the thick plate to be welded 1 is indirectly water-cooled or directly water-cooled, thereby cooperating with the liquid nitrogen rapid cooling to improve the cooling speed of the heat affected zone of the welded joint.

[0031] The application adopts the liquid nitrogen cooling method to locally rapidly cool the welding surface of the thick plate to be welded, which can effectively improve the cooling speed of the welding heat affected zone and avoid the embrittlement problem of the coarse grain heat affected zone of the welded joint.

[0032] Further, when the wall thickness of the thick plate to be welded 1 is less than 50mm, the welding groove is a single V-shaped groove, and the back of the welding surface of the thick plate to be welded 1 is water-cooled by indirect water cooling; when the wall thickness of the thick plate to be welded 1 is greater than or equal to 50mm, the welding groove is an X-shaped groove, and when welding the first surface, the back of the welding surface is cooled by direct water cooling, and when welding the other surface, the back of the welding surface is cooled by indirect water cooling.

[0033] Further, the groove angle is 30°-50°, the root is reserved 3mm-5mm, the assembly time gap is reserved 2mm-3mm. The welding current is 320A-480A, the welding voltage is 36V-44V, the welding speed is 2.9cm / min-3.6cm / min, the welding gun swing range is 10mm-15mm, the both sides stay time is 0.4s, the heat input range is 240kJ / cm-353kJ / cm, and the heat input range is 240kJ / cm-353kJ / cm. The gas-electric vertical welding wire diameter is 1.6mm, the wire dry elongation is 30mm-35mm, the welding protective gas is 100% CO2, and the gas flow is 30L / min-35L / min.

[0034] Further, the liquid nitrogen flow rate is 0.1L / min-0.2L / min, and the flow rate is too small, which will lead to poor cooling effect of the welding heat affected zone, and the flow rate is too large, which will on the one hand lead to high welding cost, and on the other hand will make the heat affected zone produce brittle structure such as lath martensite / bainite.

[0035] According to another aspect of the present application, a thick-walled gas-electric vertical welding high-performance welding device based on liquid nitrogen rapid cooling assistance is provided for performing the above method, the welding device comprising a welding torch 17, a back water cooling assembly and a front water cooling assembly, wherein the welding torch 17 is used for welding the welding groove by gas-electric vertical welding; the back water cooling assembly is arranged on the back of the welding surface of the thick plate 1 to be welded and is used for water cooling the back of the welding surface; the front water cooling assembly is arranged on the welding surface of the thick plate 1 to be welded and moves with the welding torch 17, and the front water cooling assembly comprises a water cooling slide 4 and a shielding gas channel 7, a cooling water channel 12 and a liquid nitrogen injection channel 13 arranged inside the water cooling slide 4, the shielding gas channel 7 is used for providing shielding gas during welding; the cooling water channel 12 is used for circulating cooling water to cool the water cooling slide 4 during welding to prevent the water cooling slide 4 from being melted due to high temperature; and the liquid nitrogen injection channel 13 is used for injecting liquid nitrogen to the welding joint to achieve local rapid cooling during welding.

[0036] Further, when the thick-walled gas-electric vertical welding high-performance welding device based on liquid nitrogen rapid cooling assistance is installed, the middle line of the water cooling slide 4 is strictly guaranteed to be aligned with the center line of the welding groove to be welded, and the shielding gas channel 7 is arranged at the center of the water cooling slide 4; the first water inlet 6 and the first water outlet 8 of the cooling water channel 12 are arranged on both sides of the shielding gas channel 7, respectively, and the first water inlet 6 and the first water outlet 8 are connected with a first constant-temperature circulating cooling water tank during work to realize cooling water circulation; the liquid nitrogen injection channel 13 is two, which are arranged on both sides of the first water inlet 6 and the first water outlet 8, respectively, and are opposite to the positions of the coarse grain heat affected zone on both sides of the weld, and a liquid nitrogen injector is fixed inside the liquid nitrogen injection channel 13 to realize liquid nitrogen injection cooling, and the center line of the liquid nitrogen injector should always be 1mm-2mm away from the outside of the weld fusion line to ensure that the liquid nitrogen 14 effectively acts on the coarse grain heat affected zone. More preferably, the distance between the end of the liquid nitrogen injector and the thick plate 1 to be welded should be between 1mm-3mm.

[0037] Further, when the wall thickness of the thick plate 1 to be welded is less than 50mm, as shown in Figure 1 、 2 , the back water cooling assembly comprises a back water cooling pad 2 and a water cooling pipe 3 arranged inside the back water cooling pad 2, the back water cooling pad 2 is installed at the root of the welding groove to be welded along the length direction of the thick plate 1 to be welded and is tightly attached to the back of the welding surface of the thick plate 1 to be welded, and the water cooling pipe 3 is distributed in a serpentine shape inside the back water cooling pad 2. The second water inlet 10 of the water cooling pipe 3 is arranged at the bottom of the back water cooling pad 2, and the second water outlet 11 of the water cooling pipe 3 is arranged at the top of the back water cooling pad 2, and the second water inlet 10 and the second water outlet 11 are connected with a second constant-temperature circulating cooling water tank during work to realize cooling water circulation. The temperature of the first constant-temperature circulating cooling water tank and the second constant-temperature circulating cooling water tank is set to 20℃-30℃.

[0038] Further, the width W of the back water cooling pad 2 is more than 3 times the maximum bevel width W1, i.e. W≥3W1, to ensure the water cooling effect of the back.

[0039] Further, when the wall thickness of the thick plate 1 to be welded is greater than or equal to 50 mm, as shown in Figure 3 、 4 When welding the first surface, the back water cooling assembly includes a cooling water pipe 15, which is moved synchronously with the front water cooling assembly during welding, for spraying cooling water 16 to the root of the welding bevel, thereby cooling the back of the welding surface by direct water cooling. When welding the other surface, the back water cooling assembly includes a back water cooling pad 2 and a water cooling pipe 3 arranged inside the back water cooling pad 2, the back water cooling pad 2 is arranged at the root of the welding bevel along the length direction of the thick plate 1 to be welded and is tightly attached to the thick plate 1 to be welded, and the water cooling pipe 3 is distributed in a serpentine shape inside the back water cooling pad 2.

[0040] The existing gas-electric vertical welding technology without external cooling source only limits the heat input by limiting the cross-sectional area of the bevel, or relies on the action of the water cooling slider to accelerate the cooling of the weld, which has very weak effect. By using the external cooling source, the back of the welding surface is cooled by a large-area water cooling pad or the root of the welding joint is cooled by direct water spraying during welding, the liquid nitrogen acts on the coarse-grained heat-affected zone to cause local temperature field distortion, and under the combined action of the two, the cooling speed of the welding heat-affected zone is maximized, the high-temperature residence time is reduced, the width of the welding heat-affected zone is reduced, and the toughness of the welding joint is improved.

[0041] The technical solutions provided by the present application will be further described below according to specific embodiments.

[0042] Embodiment 1

[0043] This embodiment takes a 40 mm thick high-strength steel plate as an example to provide a thick-wall gas-electric vertical welding high-performance welding method based on liquid nitrogen rapid cooling auxiliary, and the specific steps are as follows:

[0044] S1 Prepare the thick plate 1 to be welded and assemble it, the welding bevel form adopts a single-sided V-shaped bevel, the bevel angle is 35°, and the root is reserved with a blunt edge of 3 mm. The assembly time gap is reserved for 2 mm, and after the assembly is completed, as shown in Figure 1 ;

[0045] S2 Install the back water cooling pad 2, the width of the back water cooling pad 2 used is 200 mm, which is installed at the root of the bevel and tightly attached to the thick plate 1 to be welded, and a serpentine water cooling channel 3 is arranged inside, and the second water inlet 10 and the second water outlet 11 are respectively connected to the No. 2 constant-temperature circulating cooling water tank through water pipes;

[0046] S3 install water-cooled slide block 4, the middle of water-cooled slide block 4 is protective gas passage 7, both sides are first water inlet 6 and first water outlet 8 of cooling water, water-cooled slide block 4 is internally provided with cooling water passage 12, first water inlet 6 and first water outlet 8 are connected with No.1 constant temperature circulating cooling water tank through water pipe respectively;

[0047] S4 bottom filling is carried out and first liquid nitrogen sprayer 5 and second liquid nitrogen sprayer 9 are installed, the model of used welding power supply is YD-600KH, the temperature of No.1 and No.2 constant temperature circulating cooling water tank is set to 20 DEG C; No.2 constant temperature circulating cooling water tank is opened, back water-cooled backing pad 2 is connected with circulating water; No.1 constant temperature circulating cooling water tank is opened, water-cooled slide block 4 is connected with circulating water; then bottom welding filling is carried out until liquid nitrogen spray passage 13 of water-cooled slide block 4 bottom is flush with the bottom of thick plate 1 to be welded; after stopping welding, first liquid nitrogen sprayer 5 and second liquid nitrogen sprayer 9 are installed at 1 mm from fusion line on both sides of weld respectively, and the distance between end face and test plate surface is adjusted to 2 mm, so as to ensure that liquid nitrogen effectively acts on coarse-grained heat-affected zone position;

[0048] S5 first liquid nitrogen sprayer 5 and second liquid nitrogen sprayer 9 are started and gas-electric vertical welding is carried out, welding parameters are set as follows: welding current is 450 A, welding voltage is 43 V, welding speed is 3.5 cm / min, welding gun swing range is 12 mm, both sides stay time is 0.4 s, the diameter of used gas-electric vertical welding wire is 1.6 mm, wire dry elongation is 30 mm, and the welding protection gas is 100% CO2, and the gas flow is 30 L / min;

[0049] First liquid nitrogen sprayer 5 and second liquid nitrogen sprayer 9 are started and the liquid nitrogen output speed is kept at 0.1 L / min; formal welding is started, during welding, back water-cooled backing pad 2 continuously cools the whole thick plate 1 to be welded, at the same time, water-cooled slide block 4 moves upwards and drives first liquid nitrogen sprayer 5 and second liquid nitrogen sprayer 9 to move upwards synchronously, first liquid nitrogen sprayer 5 and second liquid nitrogen sprayer 9 continuously spray liquid nitrogen on coarse-grained heat-affected zone to locally and rapidly cool it until welding is finished.

[0050] After welding is finished, the fracture toughness test of welded joint is carried out according to GB 21143-2014, the sampling position is heat-affected zone, the test temperature is-20 DEG C, and the welded joint without cooling is compared, and the test curve is as shown in Figure 5 The CTOD value of the welded joint without cooling is 0.015 mm and 0.016 mm through formula calculation, the CTOD value of example 1 after cooling is 0.368 mm and 1.032 mm, and the fracture toughness is greatly improved.

[0051] Example 2

[0052] The embodiment takes an 80 mm thick high-strength steel plate as an example to provide a thick-wall gas-electric vertical welding high-performance welding method based on liquid nitrogen rapid cooling assistance, and the specific steps are as follows:

[0053] S1, prepare the thick plate 1 to be welded and assemble, the welding groove form adopts an X-shaped groove, the welding surface groove angle is 30°, the welding surface groove depth is 45 mm, the reserved bevel is 3 mm, and the welding surface back groove angle is 35°. The assembly time gap is reserved by 2 mm, and after the assembly is completed, as shown in Figure 3 ;

[0054] S2, install the cooling water pipe 15, the cooling water pipe 15 directly acts on the root of the X-shaped groove through water spraying, and the upward moving speed thereof is consistent with that of the water-cooled sliding block 4 of the welding surface during the welding process;

[0055] S3 and S4 are the same as in embodiment 1.

[0056] S5, start the first liquid nitrogen sprayer 5 and the second liquid nitrogen sprayer 9 and perform gas-electric vertical welding of the welding surface, and set the welding parameters as follows: the welding current is 460 A, the welding voltage is 44 V, the welding speed is 3.3 cm / min, and the rest of the parameters are consistent with those in embodiment 1.

[0057] S6, indirectly cool the welded one side by using the back water-cooled backing pad 2, move the water-cooled sliding block 4 to the unwelded side, start the first liquid nitrogen sprayer 5 and the second liquid nitrogen sprayer 9, and perform gas-electric vertical welding on the other side, repeat S3 and S4, and set the welding parameters as follows: the welding current is 420 A, the welding voltage is 41 V, the welding speed is 3.4 cm / min, and the rest of the parameters are consistent with those in embodiment 1.

[0058] After the welding is completed, the fracture toughness test of the welded joint is performed according to GB 21143-2014, the sampling position is the heat-affected zone, the test temperature is-20℃, and the welded joint without cooling is compared, and the test curve is as shown in Figure 6 . The CTOD values without cooling are 0.021 mm and 0.072 mm, the CTOD values after cooling in example 2 are 0.421 mm and 0.694 mm, and the fracture toughness is greatly improved.

[0059] The above results show that the welding process parameters and cooling methods developed in the application can greatly improve the fracture toughness of the heat-affected zone of the gas-electric vertical welding welded joint.

[0060] In the description of the application, it needs to be understood that the terms "first", "second" are only used for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the application, the meaning of "multiple" is two or more, unless otherwise specifically limited.

[0061] In addition, throughout the present specification, the reference to "one embodiment"; "one embodiment", "one example" or similar language means that the particular feature, structure, or characteristic described in connection with this embodiment is included in at least one embodiment of the application. Therefore, the occurrence of the phrase "in one embodiment" and similar language throughout this specification can, but does not necessarily, all refer to the same embodiment.

[0062] Those skilled in the art can easily understand that the above description is only the preferred embodiment of the present application, and is not used to limit the present application, and any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A thick-walled gas-electric vertical welding high-performance welding device based on liquid nitrogen rapid cooling assistance, characterized in that, The application relates to a welding gun (17), a back water cooling assembly and a front water cooling assembly, wherein the welding gun (17) is used for welding a welding groove by means of electro-gas vertical welding; the back water cooling assembly is arranged on the back of a welding surface of a thick plate (1) to be welded and is used for water cooling the back of the welding surface; the front water cooling assembly is arranged on the welding surface of the thick plate (1) to be welded and moves along with the welding gun (17), and the front water cooling assembly comprises a water cooling sliding block (4) and a protective gas channel (7), a cooling water channel (12) and a liquid nitrogen injection channel (13) arranged in the water cooling sliding block (4); the protective gas channel (7) is used for providing protective gas during welding; the cooling water channel (12) is used for feeding cooling water to cool the water cooling sliding block (4) during welding; and the liquid nitrogen injection channel (13) is used for injecting liquid nitrogen to the welding joint to realize local rapid cooling of a heat affected zone of the welding joint during welding. The protective gas channel (7) is arranged in the center of the water cooling sliding block (4), the first water inlet (6) and the first water outlet (8) of the cooling water channel (12) are arranged on the two sides of the protective gas channel (7) respectively, the liquid nitrogen injection channel (13) is two, and is arranged on the two sides of the first water inlet (6) and the first water outlet (8) respectively, the first liquid nitrogen injector (5) and the second liquid nitrogen injector (9) are fixed in the liquid nitrogen injection channel (13) respectively, the center lines of the first liquid nitrogen injector (5) and the second liquid nitrogen injector (9) are 1mm-2mm away from the outside of a welding bead fusion line respectively, and the distance between the end of the first liquid nitrogen injector (5) and the end of the second liquid nitrogen injector (9) and the welding surface of the thick plate (1) to be welded is 1mm-3mm. When the wall thickness of the thick plate (1) to be welded is greater than 30mm and less than 50mm, the welding groove is a single-side V-shaped groove, the back water cooling assembly comprises a back water cooling pad (2) and a water cooling pipeline (3) arranged in the back water cooling pad (2), the back water cooling pad (2) is arranged at the root of the welding groove along the length direction of the thick plate (1) to be welded and is tightly attached to the thick plate (1) to be welded, and the water cooling pipeline (3) is arranged in the back water cooling pad (2) in a serpentine shape, so that the back water cooling assembly is used to indirectly cool the back of the welding surface. When the wall thickness of the thick plate to be welded (1) is greater than or equal to 50 mm, the welding groove is an X-shaped groove, and when welding the first surface, the back water cooling assembly comprises a cooling water pipe (15) which is synchronously moved with the front water cooling assembly during welding and used for spraying water to the root of the welding groove, so that the back surface of the welding surface is cooled in a direct water cooling manner by the back water cooling assembly; when welding the other surface, the back water cooling assembly comprises a back water cooling pad (2) and a water cooling pipe (3) arranged inside the back water cooling pad (2), the back water cooling pad (2) is arranged at the root of the welding groove along the length direction of the thick plate to be welded (1) and closely attached to the thick plate to be welded (1), and the water cooling pipe (3) is distributed in a serpentine shape inside the back water cooling pad (2), so that the back surface of the welding surface is cooled in an indirect water cooling manner by the back water cooling assembly.

2. The welding device of claim 1, wherein The water inlet of the water cooling pipe (3) is arranged at the bottom of the back water cooling pad (2), and the water outlet of the water cooling pipe (3) is arranged at the top of the back water cooling pad (2).

3. The welding device of claim 1, wherein The width of the back water cooling pad (2) is more than 3 times the maximum groove width of the welding groove.

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