Low-temperature liquid tank container cylinder deep fusion welding back protection tooling

Abstract

The application discloses a back protection tool for deep penetration welding of a low-temperature liquid tank container cylinder, which comprises a back gas protection assembly arranged at a welding pool position on the back of a butt joint welding seam of the cylinder, wherein the back gas protection assembly comprises a bladeless fan, a ring-shaped air guide chamber butted on a ring-shaped air outlet on the front end of the bladeless fan, an air inlet box sleeved on the outer circle of the handle part of the bladeless fan and used for surrounding the air inlet on the outer circle of the handle part of the bladeless fan, and a rear end sealing baffle arranged at the rear end of the bladeless fan and used for sealing the rear part of the hollow part of the bladeless fan; the rear end sealing baffle is connected with a first protection gas supply pipe which is communicated with the hollow part of the bladeless fan; the air inlet box is connected with a second protection gas supply pipe which is communicated with the inside of the air inlet box; and the ring-shaped air guide chamber is provided with a ring-shaped air guide opening, and the protection gas direction of the ring-shaped air guide opening is towards the back of the welding pool. The application improves the welding stability and the welding seam quality of the deep penetration argon arc welding.

Description

Technical Field

[0001] This invention relates to the field of welding process equipment technology, specifically to a back protection tooling for deep penetration welding of cryogenic liquid tank container bodies. Background Technology

[0002] A cryogenic liquid tank container is a mobile pressure vessel with an external supporting frame used for transporting cryogenic liquids. The core components of a cryogenic liquid tank container are the inner and outer cylinders, forming a space between them. This space is evacuated to ensure the container's thermal insulation performance. Both the inner and outer cylinders of a cryogenic liquid tank container are welded structures, each consisting of a cylinder and end caps connected to both ends. The cylinder is formed by rolling steel plates on a plate rolling machine and then welding them together. When the cylinder is long, it needs to be divided into several sub-cylinders and then spliced ​​and welded together to form a complete cylinder.

[0003] Currently, the most efficient welding method used for butt welding of cryogenic liquid tank container bodies is deep penetration TIG welding. This method, based on traditional TIG welding, utilizes a specially designed welding torch with high current (greater than 300A) and efficient cooling to achieve deep penetration. During deep penetration TIG welding, a small welding hole is formed in the molten metal pool. Under the combined action of the arc force, the gravity of the molten pool, and the surface tension of the molten metal, this hole remains stable during the welding process. As the arc recedes, the hole continuously closes, and the molten metal cools and crystallizes to form the weld. This process continues until the entire deep penetration welding process is completed. Deep penetration TIG welding is characterized by deep penetration and high efficiency. It can achieve single-sided welding with double-sided forming on workpieces up to 12mm thick without beveling, and produces aesthetically pleasing welds with minimal deformation. It is a cost-effective and efficient welding method.

[0004] However, when performing deep penetration TIG welding, the influence of the thermal conductivity of the welding material and the surface tension of the molten pool on the deep penetration TIG welding process must be fully considered. For the welding of cylinders made of some special materials, it is also necessary to add a back shielding gas to the back of the weld to improve weld quality. In addition, it is also necessary to ensure that the surface tension of the molten pool is greater than the sum of the weight of the molten pool metal and the arc pressure during the welding process in order to form a stable weld. Summary of the Invention

[0005] To address the aforementioned problems, this invention proposes a back-protection fixture for deep penetration welding of cryogenic liquid tank container bodies, aiming to improve the welding stability and weld quality of deep penetration argon arc welding. The specific technical solution is as follows:

[0006] A back protection fixture for deep penetration welding of a cryogenic liquid tank container includes a back gas protection assembly disposed on the weld pool portion on the back side of the butt weld of the cryogenic liquid tank container. The back gas protection assembly includes a bladeless fan, an annular air guide chamber connected to the annular air outlet at the front end of the bladeless fan, an air inlet box sleeved on the outer circle of the handle of the bladeless fan to surround the air intake on the outer circle of the handle of the bladeless fan, and a rear end sealing baffle disposed at the rear end of the bladeless fan to seal the rear part of the hollow portion of the bladeless fan. A first protective gas supply pipe connected to the hollow portion of the bladeless fan is connected to the rear end sealing baffle. A second protective gas supply pipe connected to the interior of the air inlet box is connected to the air inlet box. An annular air guide port is provided on the annular air guide chamber, with the protective gas directed towards the back side of the weld pool.

[0007] Preferably, the annular air guide chamber includes a straight annular air guide chamber formed by an inner sleeve and an outer sleeve that are coaxially fitted together, and a conical annular air guide chamber that is connected to the front end of the straight annular air guide chamber, wherein the annular air guide port is located at the front end of the conical annular air guide chamber.

[0008] The conical annular air guide chamber is formed by an inner conical sleeve and an outer conical sleeve that are coaxially fitted together; the inner conical sleeve is connected to the inner sleeve, and the outer conical sleeve is connected to the outer sleeve.

[0009] As a further improvement of the present invention, a protective gas forced cooling module is also provided on the annular air guide chamber. The protective gas forced cooling module includes designing the outer sleeve as a semiconductor refrigeration outer sleeve. The semiconductor refrigeration outer sleeve is formed by connecting a number of semiconductor refrigeration chips around the outer sleeve in a circumferential direction. The side of the semiconductor refrigeration chip located inside the outer sleeve is the cooling surface, and the side of the semiconductor refrigeration chip located outside the outer sleeve is the heat dissipation surface.

[0010] As a further improvement of the present invention, the protective gas forced cooling module further includes designing the inner sleeve as a semiconductor cooling inner sleeve, the semiconductor cooling inner sleeve being formed by a number of semiconductor cooling chips connected circumferentially, and the side of the semiconductor cooling chip located on the outside of the inner sleeve being the cooling surface, the side of the semiconductor cooling chip located on the inside of the inner sleeve being the heat dissipation surface, and a surrounding plate is used to form an annular heat dissipation chamber along the circumferential direction on the inner wall of the inner sleeve, a number of spaced air inlets are provided at the lower surrounding plate of the annular heat dissipation chamber, and a heat dissipation pipe leading to the outside is provided at the upper part of the annular heat dissipation chamber.

[0011] Preferably, narrow annular gaps are formed between the inner sleeve and the outer sleeve, and between the inner conical sleeve and the outer conical sleeve, respectively, to serve as annular air guide chambers, so that the protective gas entering the annular air guide chambers can quickly flow over the heat dissipation surface of the semiconductor cooling chip, thereby enhancing the heat dissipation speed.

[0012] To further improve the quality of the weld, a further improvement is proposed: the back gas protection assembly further includes a back trailing gas protection module for post-weld gas protection of the back of the deep penetration weld, which is installed on the back of the weld. The back trailing gas protection module includes a protective gas box close to the back of the weld, and micro-vent holes are densely distributed on the side of the protective gas box facing the back of the weld. The heat dissipation pipe output end of the protective gas forced cooling module is connected to the interior of the protective gas box.

[0013] Preferably, the heat dissipation pipe is equipped with a miniature exhaust fan for forcibly expelling the hot gas inside the annular heat dissipation chamber.

[0014] Preferably, the shape of the side of the protective gas box facing the back of the weld is adapted to the shape of the inner wall of the cylinder.

[0015] In this invention, the protective gas box is fixedly connected to one side of the front part of the conical annular air guide chamber.

[0016] A protection method for a back protective fixture used in deep penetration welding of cryogenic liquid tank container shells includes the following steps:

[0017] (1) Workpiece installation: After assembling and spot welding the pair of cylinders that need to be butt welded together, place them on the welding roller frame on the welding workbench;

[0018] (2) Tooling installation: A bracket that passes through the inner hole of the welding cylinder is fixed on the welding workbench, and the back gas protection component is fixed on the bracket; during installation, pay attention to the center of the annular air guide on the back gas protection component being close to and aligned with the welding point of the butt weld of the cylinder.

[0019] (3) Deep penetration welding: Connect the first and second shielding gas supply pipes, connect the power supply to the semiconductor cooling chip and the bladeless fan, turn on the welding roller frame to drive the assembly cylinder to rotate, and use a deep penetration argon arc welding machine as the welding equipment to perform deep penetration welding on the butt ring weld of the assembly cylinder; during deep penetration welding, a weld pool penetrating the wall thickness of the cylinder is formed at the welding position of the cylinder targeted by the welding torch, and a continuous circumferential weld is formed as the assembly cylinder rotates and the weld pool gradually cools; during the welding process, the shielding gas from the first shielding gas supply pipe enters the bladeless fan. The hollow part of the shielding gas is blown through the central channel of the annular air guide chamber toward the back of the weld pool, thus forming the first protection for the back of the weld pool. At the same time, the shielding gas from the second shielding gas supply pipe enters the suction port of the bladeless fan. The bladeless fan pressurizes the shielding gas and outputs it. After being cooled by the semiconductor cooling chip, it is blown out from the annular air guide port on the annular air guide chamber, forming the second protection for the back of the weld pool. The pressurized and cooled shielding gas forms a lifting effect on the back of the weld pool and enhances the surface tension of the back of the weld pool, thus forming a stable weld pool.

[0020] Preferably, in the deep penetration welding process of step (3), a portion of the protective gas that enters the hollow part of the bladeless fan through the first protective gas supply pipe is diverted through the air inlet on the enclosure into the annular heat dissipation chamber to cool the heat dissipation surface of the semiconductor cooling chip on the semiconductor cooling inner sleeve. Then, it is transported through the heat dissipation pipe to the protective gas box of the tail gas protection module on the back of the weld, and blown towards the welded weld through the densely distributed micro air outlets on the protective gas box, thereby forming the tail gas protection on the back of the cylinder butt weld.

[0021] The beneficial effects of this invention are:

[0022] First, the present invention provides a back protection tooling for deep penetration welding of cryogenic liquid tank container cylinders, which employs a dual-path shielding gas delivery structure. One path of shielding gas passes through the central channel of the annular air guide chamber and directly reaches the back of the weld pool, thereby providing basic gas protection for the back of the weld. The other path of shielding gas is pressurized by a bladeless fan and blown towards the back of the weld pool through the annular air guide port of the annular air guide chamber. The rapidly flowing shielding gas can cool the back of the weld pool, thereby increasing the surface tension of the weld pool. On the other hand, the pressurized shielding gas can also support the weld pool. The two work together to improve the welding stability and weld quality of deep penetration argon arc welding.

[0023] Secondly, the back protection tooling for deep penetration welding of cryogenic liquid tank container cylinders of the present invention has a specially designed protective gas forced cooling module, which allows the pressurized protective gas to be rapidly cooled by a semiconductor cooling chip and then blown toward the back of the weld pool, which can further increase the surface tension of the weld pool, prevent the weld pool from collapsing, accelerate the weld formation, and thus improve the welding stability.

[0024] Third, the back protection tooling for deep penetration welding of cryogenic liquid tank container cylinders of the present invention allows the heat dissipation gas of the semiconductor refrigeration chip to be discharged in a timely manner through the heat dissipation pipe, which is beneficial to improving the cooling performance of the semiconductor refrigeration chip. In addition, the heat dissipation gas enters the back trailing gas protection module of the weld through the heat dissipation pipe, and the trailing gas of the weld is fully utilized. Moreover, the trailing gas has heat, which can prevent the weld from cooling too quickly after welding, thereby reducing welding stress and further improving the weld quality. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the back protection tooling for deep penetration welding of a cryogenic liquid tank container body according to the present invention;

[0026] Figure 2 This is a cross-sectional view of the annular air guide chamber in the back gas protection assembly; the inner and outer semiconductor cooling sleeves in the figure are each composed of six semiconductor cooling plates connected circumferentially.

[0027] In the diagram: 1. Back gas protection assembly, 2. Bladeless fan, 3. Annular air guide chamber, 4. Outer circle of the handle, 5. Air inlet, 6. Air inlet box, 7. Hollow part, 8. Rear sealing baffle, 9. First protective gas supply pipe, 10. Second protective gas supply pipe, 11. Annular air guide, 12. Inner sleeve (semiconductor cooling inner sleeve), 13. Outer sleeve (semiconductor cooling outer sleeve), 14. Straight annular air guide chamber, 15. Conical annular air guide chamber, 16. Protective gas forced cooling module, 17. Semiconductor cooling chip, 18. Cooling surface, 19. Heat dissipation surface, 20. Enclosure, 21. Annular heat dissipation chamber, 22. Air inlet, 23. Heat dissipation pipe, 24. Weld seam back trailing gas protection module, 25. Protective gas box, 26. Miniature air outlet, 27. Miniature exhaust fan, 28. Cylinder body, 29. Support, 30. Deep penetration argon arc welding torch, 31. Weld pool. Detailed Implementation

[0028] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and examples. The following examples are only used to more clearly illustrate the technical solutions of the present invention and should not be construed as limiting the scope of protection of the present invention.

[0029] Example 1:

[0030] like Figures 1 to 2The illustration shows an embodiment of a back protection fixture for deep penetration welding of a cryogenic liquid tank container body according to the present invention. It includes a back gas protection assembly 1 disposed on the weld pool portion on the back side of the butt weld of the cryogenic liquid tank container body. The back gas protection assembly 1 includes a bladeless fan 2, an annular air guide chamber 3 connected to the annular air outlet at the front end of the bladeless fan 2, an air inlet box 6 sleeved on the outer circle 4 of the handle of the bladeless fan 2 to surround the air intake 5 on the outer circle 4 of the handle of the bladeless fan 2, and a rear sealing baffle 8 disposed at the rear end of the bladeless fan 2 to seal the rear part of the hollow portion 7 of the bladeless fan 2. A first protective gas supply pipe 9 connected to the hollow portion 7 of the bladeless fan 2 is connected to the rear sealing baffle 8. A second protective gas supply pipe 10 connected to the interior of the air inlet box 6 is connected to the air inlet box 6. An annular air guide port 11 is provided on the annular air guide chamber 3, with the protective gas directed towards the back of the weld pool 31.

[0031] Preferably, the annular air guide chamber 3 includes a straight annular air guide chamber 14 formed by an inner sleeve 12 and an outer sleeve 13 coaxially fitted together, and a conical annular air guide chamber 15 connected to the front end of the straight annular air guide chamber 14, wherein the annular air guide port 11 is located at the front end of the conical annular air guide chamber 15.

[0032] The conical annular air guide chamber 15 is formed by an inner conical sleeve and an outer conical sleeve that are coaxially fitted together; the inner conical sleeve is connected to the inner sleeve 12, and the outer conical sleeve is connected to the outer sleeve 13.

[0033] As a further improvement of this embodiment, a protective gas forced cooling module 16 is also provided on the annular air guide chamber 3. The protective gas forced cooling module 16 includes designing the outer sleeve 13 as a semiconductor cooling outer sleeve. The semiconductor cooling outer sleeve is formed by connecting a number of semiconductor cooling chips 17 around the circumference. The side of the semiconductor cooling chip 17 located inside the outer sleeve 13 is the cooling surface 18, and the side of the semiconductor cooling chip 17 located outside the outer sleeve 13 is the heat dissipation surface 19.

[0034] As a further improvement of this embodiment, the protective gas forced cooling module 16 further includes designing the inner sleeve 12 as a semiconductor cooling inner sleeve. The semiconductor cooling inner sleeve is formed by connecting a number of semiconductor cooling chips 17 around the inner sleeve 12 in a circumferential direction. The side of the semiconductor cooling chip 17 located on the outside of the inner sleeve 12 is the cooling surface 18, and the side of the semiconductor cooling chip 17 located on the inside of the inner sleeve 12 is the heat dissipation surface 19. A surrounding plate 20 is used to form an annular heat dissipation chamber 21 around the inner wall of the inner sleeve 12. A number of spaced air inlets 22 are provided at the lower part of the surrounding plate 20 of the annular heat dissipation chamber 21. A heat dissipation pipe 23 leading to the outside is provided at the upper part of the annular heat dissipation chamber 21.

[0035] Preferably, narrow annular gaps are formed between the inner sleeve 12 and the outer sleeve 13, and between the inner conical sleeve and the outer conical sleeve, respectively, to form an annular air guide chamber 3, so that the protective gas entering the annular air guide chamber 3 can flow quickly over the heat dissipation surface of the semiconductor cooling chip 17, thereby enhancing the heat dissipation speed.

[0036] To further improve the quality of the weld, a further improvement is as follows: the back gas protection component 1 also includes a back tail gas protection module 24 for post-weld gas protection of the back of the deep penetration weld. The back tail gas protection module 24 includes a protective gas box 25 close to the back of the weld. The protective gas box 25 has numerous micro-vent holes 26 on the side facing the back of the weld. The output end of the heat dissipation pipe 23 on the protective gas forced cooling module 16 is connected to the interior of the protective gas box 25.

[0037] Preferably, the heat dissipation pipe 23 is provided with a miniature exhaust fan 27 for forcibly expelling the hot gas inside the annular heat dissipation chamber 21.

[0038] Preferably, the shape of the side of the protective gas box 25 facing the back of the weld is adapted to the shape of the inner wall of the cylinder.

[0039] In this embodiment, the protective gas box 25 is fixedly connected to one side of the front part of the conical annular air guide chamber 15.

[0040] Example 2:

[0041] A protection method for the back protection fixture used in the deep penetration welding of a cryogenic liquid tank container cylinder according to Example 1 includes the following steps:

[0042] (1) Workpiece installation: After assembling and spot welding the pair of cylinders 28 that need to be butt welded together, place them on the welding roller frame on the welding workbench;

[0043] (2) Tooling installation: A bracket 29 passing through the inner hole of the welding cylinder 28 is fixed on the welding workbench, and the back gas protection component 1 is fixed on the bracket 29; during installation, pay attention to the center of the annular air guide 11 on the back gas protection component 1 being close to and aligned with the welding joint of the butt weld of the cylinder 28.

[0044] (3) Deep penetration welding: Connect the first protective gas supply pipe 9 and the second protective gas supply pipe 10, connect the power supply of the semiconductor cooling chip 17 and the bladeless fan 2, turn on the welding roller frame to drive the assembly cylinder 28 to rotate, and use a deep penetration argon arc welding machine as the welding equipment to perform deep penetration welding on the butt ring weld of the assembly cylinder 29; during deep penetration welding, a weld pool 31 penetrating the cylinder wall thickness is formed at the welding position of the cylinder aligned with the welding torch 30, and a continuous circumferential weld is formed as the assembly cylinder 28 rotates and the weld pool gradually cools; during the welding process, the protective gas from the first protective gas supply pipe 9 enters the middle of the bladeless fan 2 The air is blown through the central channel of the annular air guide chamber 3 to the back of the weld pool 31, thus forming the first protection for the back of the weld pool 31. At the same time, the protective gas from the second protective gas supply pipe 10 enters the air intake 5 of the bladeless fan 2. The bladeless fan 2 pressurizes the protective gas and outputs it. After being cooled by the semiconductor cooling chip 17, it is blown out from the annular air guide port 11 on the annular air guide chamber 3, forming the second protection for the back of the weld pool 31. The pressurized and cooled protective gas forms a lifting effect on the back of the weld pool 31 and enhances the surface tension of the back of the weld pool 31, thus forming a stable weld pool.

[0045] Preferably, in the deep penetration welding process of step (3), a portion of the protective gas that enters the hollow part 7 of the bladeless fan 2 through the first protective gas supply pipe 9 is diverted into the annular heat dissipation chamber 21 through the air inlet 22 on the enclosure plate 20 to cool the heat dissipation surface 19 of the semiconductor cooling chip 17 on the semiconductor cooling inner sleeve 12. Then, it is transported to the protective gas box 25 of the weld back trailing gas protection module 24 through the heat dissipation pipe 23, and blown towards the welded weld through the densely distributed micro air outlets 26 on the protective gas box 25, thereby forming the trailing gas protection of the back of the weld between the cylinder 28 and the weld.

[0046] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A back protection tooling for deep penetration welding of a cryogenic liquid tank container shell, characterized in that, The device includes a back gas protection assembly for the weld pool on the back side of the butt weld of a cryogenic liquid tank container. The back gas protection assembly includes a bladeless fan, an annular air guide chamber connected to the annular air outlet at the front end of the bladeless fan, an air inlet box fitted over the outer circle of the handle of the bladeless fan to surround the air intake on the outer circle of the handle of the bladeless fan, and a rear sealing baffle located at the rear end of the bladeless fan to seal the rear part of the hollow part of the bladeless fan. The rear sealing baffle is connected to a first protective gas supply pipe communicating with the hollow part of the bladeless fan. The air inlet box is connected to a second protective gas supply pipe communicating with the inside of the air inlet box. The annular air guide chamber is provided with an annular air guide port that blows the protective gas toward the back side of the weld pool. The annular air guide chamber includes a straight annular air guide chamber formed by an inner sleeve and an outer sleeve that are coaxially fitted together, and a conical annular air guide chamber that is connected to the front end of the straight annular air guide chamber. The annular air guide port is located at the front end of the conical annular air guide chamber. A protective gas forced cooling module is also provided on the annular air guide chamber. The protective gas forced cooling module includes designing the outer sleeve as a semiconductor refrigeration outer sleeve. The semiconductor refrigeration outer sleeve is formed by connecting a number of semiconductor refrigeration chips around the circumference. The side of the semiconductor refrigeration chip located inside the outer sleeve is the cooling surface, and the side of the semiconductor refrigeration chip located outside the outer sleeve is the heat dissipation surface. The protective gas forced cooling module further includes an inner sleeve designed as a semiconductor cooling inner sleeve. The semiconductor cooling inner sleeve is formed by connecting a number of semiconductor cooling chips around the inner sleeve in a circumferential direction. The side of the semiconductor cooling chip on the outside of the inner sleeve is the cooling surface, and the side of the semiconductor cooling chip on the inside of the inner sleeve is the heat dissipation surface. A surrounding plate is used to form an annular heat dissipation chamber around the inner wall of the inner sleeve. A number of spaced air inlets are provided at the lower part of the surrounding plate of the annular heat dissipation chamber. A heat dissipation pipe leading to the outside is provided at the upper part of the annular heat dissipation chamber.

2. The back protection tooling for deep penetration welding of a cryogenic liquid tank container shell according to claim 1, characterized in that, The back gas protection assembly also includes a back tail gas protection module for post-weld gas protection of the back of the deep penetration weld, which is installed on the back of the weld. The back tail gas protection module includes a protective gas box close to the back of the weld. The protective gas box has micro-vent holes densely distributed on the side facing the back of the weld. The heat dissipation pipe output end of the protective gas forced cooling module is connected to the inside of the protective gas box.

3. The back protection tooling for deep penetration welding of a cryogenic liquid tank container shell according to claim 2, characterized in that, The heat dissipation pipe is equipped with a miniature exhaust fan for forcibly expelling the hot gas inside the annular heat dissipation chamber.

4. The back protection tooling for deep penetration welding of a cryogenic liquid tank container shell according to claim 2, characterized in that, The shape of the side of the protective gas box facing the back of the weld is adapted to the shape of the inner wall of the cylinder.

5. The back protection tooling for deep penetration welding of a cryogenic liquid tank container shell according to claim 2, characterized in that, The protective gas box is fixedly connected to one side of the front of the conical annular air guide chamber.

6. A method for protecting the back of a cryogenic liquid tank container body undergoing deep penetration welding, wherein the cryogenic liquid tank container body undergoing deep penetration welding as described in any one of claims 2-5 is used, characterized in that... Includes the following steps: Step 1, workpiece installation: After assembling and spot welding the pair of cylinders that need to be butt welded together, place them on the welding roller frame on the welding workbench. Step 2, Fixture installation: Fix a bracket that passes through the inner hole of the welding cylinder on the welding workbench, and fix the back gas protection component on the bracket; the center of the annular air guide on the back gas protection component is close to and aligned with the welding point of the butt weld of the cylinder. Step 3, Deep Penetration Welding: Connect the first and second shielding gas supply pipes, turn on the power to the semiconductor cooling chip and bladeless fan, turn on the welding roller frame to drive the assembly cylinder to rotate, and use a deep penetration argon arc welding machine as the welding equipment to perform deep penetration welding on the butt joint circumferential weld of the assembly cylinder; during deep penetration welding, a weld pool penetrating the cylinder wall thickness is formed at the welding position of the cylinder targeted by the welding torch, and a continuous circumferential weld is formed as the assembly cylinder rotates and the weld pool gradually cools; during the welding process, the shielding gas from the first shielding gas supply pipe enters the hollow part of the bladeless fan and passes through the central channel of the annular air guide chamber to blow towards the back of the weld pool, thus forming the first protection on the back of the weld pool; at the same time, the shielding gas from the second shielding gas supply pipe enters the air intake of the bladeless fan, the bladeless fan pressurizes the shielding gas and outputs it, and after being cooled by the semiconductor cooling chip, it is blown out from the annular air guide port on the annular air guide chamber, forming the second protection on the back of the weld pool.

7. The protection method of the back protective fixture for deep penetration welding of cryogenic liquid tank container shell according to claim 6, characterized in that, During the deep penetration welding process in step 3, a portion of the protective gas that enters the hollow part of the bladeless fan through the first protective gas supply pipe is diverted through the air inlet on the enclosure into the annular heat dissipation chamber to cool the heat dissipation surface of the semiconductor cooling chip on the semiconductor cooling inner sleeve. Then, it is transported through the heat dissipation pipe to the protective gas box of the tail gas protection module on the back of the weld, and blown onto the welded weld through the densely distributed micro air outlets on the protective gas box, thereby forming a tail gas protection on the back of the cylinder butt weld.

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