Flexible inert gas protection device and method for pipe welding

Abstract

The invention discloses a flexible inert gas protection device and method for pipe welding, and belongs to the technical field of welding. The device comprises a fixed joint and a plurality of movable joints, the fixed joint is detachably fixed at the gun head position of the plasma welding gun; the movable joints are sequentially connected to the rear portions of the fixed joints, flexible adjustment of spatial poses is achieved through the connecting pivots and the curved sliding grooves, and therefore the requirements for different pipe diameters and complex welding positions are met. The gas inlets in the surfaces of the fixed joint and the movable joint are used for conveying shielding gas, the bottom ends of the gas inlets are connected with a gas distributor, cavities are formed in the gas inlets and used for temporarily storing the shielding gas, and gas distribution holes are evenly distributed in the side walls and used for evenly dispersing the shielding gas and covering a post-welding area. A circulating water path is arranged in the movable joint and is used for introducing circulating cooling water to maintain the temperature stability of the device body and the protective gas in the welding process; according to the device, through a flexible adjustable structure, active water-cooling temperature control and uniform gas distribution, the quality stability of pipe welding is remarkably improved, and the service life of the gas protection device is prolonged.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of welding, and particularly relates to a flexible inert gas protection device and protection method for pipe welding. BACKGROUND

[0002] Pipe welding is a key process in industrial manufacturing, especially in the oil, gas, and chemical industries. The welding quality of the pipe system directly affects the safety and reliability of the system. Traditional pipe welding methods usually use inert gas protection welding or plasma welding, which requires providing inert gas in the welding area to prevent air from reacting with the joint position, resulting in weld defects.

[0003] Existing pipe welding gas protection devices mainly focus on controlling gas flow and reducing gas waste. For example, US patent US7019248B1 describes a welding protection gas flow control device that improves the quality of the weld start by providing additional protective gas to exclude air at the beginning of welding. Similarly, US patents US6610957B2 and US7015412B1 propose devices to reduce protective gas waste by controlling gas flow rate and storing gas volume. These devices mainly address the problem of gas waste, but do not fully consider the adaptability of large-diameter pipes or temperature control in high-temperature environments.

[0004] For the protection of the inside of the pipe, Japanese patent JP5610715B2 proposes a method of using a foaming agent to form a foam layer to maintain an inert gas atmosphere inside the pipe. However, this method may have limitations in handling large-diameter pipes and may not ensure uniform distribution of gas in the welding area. Most of the above devices are designed for specific pipe diameters, making it difficult to adapt to large-diameter pipes with larger diameters, and in high-temperature welding environments, the device body and protective gas are prone to overheating, affecting the gas protection effect and welding quality, and lacking effective active cooling mechanisms. Therefore, it is necessary to develop a flexible inert gas protection device for pipe welding that can adapt to different pipe diameters, ensure uniform gas distribution, and maintain appropriate temperature. SUMMARY

[0005] The present application aims to solve the problems of poor inert gas protection effect for large-diameter pipes and overheating of protective gas in high-temperature welding environments, and proposes a flexible inert gas protection device for pipe welding.

[0006] The present application provides a flexible inert gas protection device for pipe welding, comprising a fixed joint with a pre-set hollow area at the bottom, a movable joint, and a gas distributor located in the hollow area; the hollow area is a cavity formed by the inward recess of the bottom of the fixed joint and the movable joint;

[0007] The fixed joint comprises a surface laid air inlet, a welding gun fixing hole I, and a welding gun fixing hole II; the clamping tool fixing hole I and the clamping tool fixing hole II are connected with the clamping tool, which can clamp the plasma welding gun, and the plasma welding gun is attached to the clamping end of the fixed joint; the air inlet is connected with the gas distributor;

[0008] The movable joint comprises a surface laid water inlet, a water outlet, and an air inlet; the lower ends of the water inlet and the water outlet are respectively connected with the horizontal section of the closed cooling water storage circuit at the bottom, forming two outlet upward branches; the closed cooling water storage circuit is a hollow structure with an internal cavity, and the two ends thereof extend to the two side walls of the movable joint to form horizontal sections; the water inlet, the water outlet, and the closed cooling water storage circuit constitute a circulating water circuit;

[0009] The gas distributor is connected with the fixed joint and the movable joint; the gas distributor is a closed structure with an internal cavity, a hole at the top surface connected with the air inlet, and uniform holes at the two side walls through which the protective gas entering the air inlet is released;

[0010] The fixed joint is installed at the rear of the movable joint, and the front end of the movable joint clamps the plasma welding gun. A through connecting pivot is arranged at the bottom between the fixed joint and the movable joint, and a curved sliding groove is arranged at the front end of the movable joint to adjust the angle between the fixed joint and the movable joint.

[0011] Further, the movable joint is two or more, and a through connecting pivot is arranged at the bottom between the movable joints, and a curved sliding groove at the front end of the movable joint adjusts the angle between the movable joints; the total protection length of the fixed joint and the movable joint is 160-200 mm.

[0012] Further, the movable joint rotates around the connecting pivot, and the clockwise rotation angle is 0-31°, and the counterclockwise rotation angle is 0-4°.

[0013] Further, the gas distributor is arranged at a certain distance from the hollow area inner wall of the fixed joint and the movable joint, and the distance is 5-15 mm; the diameter of the holes at the two side walls of the gas distributor is 2-5 mm.

[0014] Further, the fixed joint and the movable joint are coated with fireproof adhesive tape on the wall surface, which is used to prevent external air from penetrating into the protection area and excessive overflow of the protective gas from the gas distributor, thereby indirectly reducing the amount of protective gas, improving the utilization efficiency of the protective gas.

[0015] Further, the circulating water circuits of the multiple movable joints are connected to form an overall circulating water circuit.

[0016] Further, the fixed section front end clamping end surface shape is same as the torch head shape of the plasma welding torch, and the fixed section clamping end can be closely fitted with the torch head of the plasma welding torch.

[0017] The application also provides a protection method of the flexible inert gas protection device for pipe welding, characterized by comprising:

[0018] Step 1: install the flexible inert gas protection device; after installation, the clamping tool on the fixed section clamps the plasma welding torch, so that the torch head of the plasma welding torch is closely fitted with the fixed section clamping end;

[0019] Step 2: according to the diameter and welding position of the pipe to be welded, the angle of the movable section is adjusted by adjusting the sliding groove and the connecting pivot, so that the gas distributor is located directly above the post-welding area, and a certain distance is provided between each gas distributor and the pipe surface, and the distance is equal;

[0020] Step 3: connect the cooling water to the overall circulating water path of the movable section; connect the protective gas to the gas inlet of the fixed section and the movable section, and control the protective gas flow;

[0021] Step 4: open the protective gas and cooling water before welding; the protective gas is transported to the pipe surface through the internal passage of the device, forms a uniform protective gas curtain covering the welding area after flow equalization, and then starts welding, and the protective gas forms a uniform protective gas curtain covering the post-welding high-temperature area after flow equalization; after welding, the protective gas and cooling water are closed in turn.

[0022] Further, the distance between the protection device and the pipe surface to be welded is 3-8 mm.

[0023] Further, the pipe diameter is 200-500 mm.

[0024] The application has the following beneficial effects:

[0025] (1) The application innovatively adopts the series connection design of "fixed section + movable section", realizes the inert gas protection of the protective gas around the post-welding area of the pipe, and realizes the multi-degree-of-freedom space pose adjustment through the combination of the curved sliding groove and the connecting pivot.

[0026] (2) The application adopts an integrated active water cooling system, and a closed circulating water cooling passage is designed in the device. The temperature of the device body and the protective gas flowing through the internal passage is maintained in a lower range by external circulating cooling water. This effectively prevents the failure of the protective gas caused by high temperature, the deformation of the device and the adverse effect on the quality of the welding seam, and significantly improves the welding stability and protection effect in high temperature environment.

[0027] (3) The design of the device optimizes the uniform distribution mechanism of the protective gas. The gas distributor is arranged at the lower end of the fixed joint and the movable joint. The protective gas enters the buffer cavity of the gas distributor through the gas inlet, and is uniformly distributed in the buffer cavity. The gas is forced to pass through the gas distribution holes uniformly distributed in the side wall of the buffer cavity. This design breaks the straight jet flow state of the gas, forms a uniform and diffuse protective gas curtain, and at the same time wraps fireproof tape around the fixed joint and the movable joint, ensuring that the inert gas uniformly covers the entire post-weld high temperature area without dead angle, and maximizes the inhibition of air intrusion and oxidation reaction.

[0028] (4) The device of the application protects the post-weld area during welding, reduces the proportion of welding seam pores and cracks by more than 15%, reduces the thickness of the oxidation layer by 30%, and improves the welding seam strength and corrosion resistance. And adapt to 200mm to 500mm diameter pipe, meet the needs of petroleum, chemical industry and other industries. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 is a schematic diagram of the flexible inert gas protection device of the application;

[0030] Figure 2 is a schematic diagram of the gas distributor of the flexible inert gas protection device of the application;

[0031] Figure 3 is a diagram of the actual application state of the flexible inert gas protection device of the application after the movable joint is rotated;

[0032] Figure 4 is a schematic diagram of the overall circulating water path and gas flow direction of the flexible inert gas protection device of the application;

[0033] Figure 5 is a physical diagram of the pipe after being welded by the welding gun.

[0034] The reference signs are: 1, fixed section; 2, first movable section; 3, second movable section; 101, clamping end; 102, clamping tool fixing hole I; 103, clamping tool fixing hole II; 104, air inlet I; 105, gas distributor fixing hole I; 201, curved chute I; 202, connecting pivot I; 203, water inlet I; 204, water outlet I; 205, air inlet II; 206, gas distributor fixing hole II; 207, cooling water closed flow storage circuit I; 301, curved chute II; 302, connecting pivot II; 303, water inlet II; 304, water outlet II; 305, air inlet III; 306, gas distributor fixing hole III; 207, cooling water closed flow storage circuit II; 308, reserved hole; 309, connecting pivot III; 4, gas distributor; 401, cavity; 402, fixing hole; 403, gas distribution hole. DETAILED DESCRIPTION

[0035] The application will be further described below in combination with the drawings.

[0036] The application discloses a flexible inert gas protection device for pipe welding, comprising:

[0037] The fixed section 1 is used for detachable fixing to a welding torch. The fixed section 1 is provided with a clamping end 101, clamping tool fixing hole I 102, clamping tool fixing hole II 103, air inlet I 104, gas distributor fixing hole I 105, reserved hole and through connecting pivot hole; the shape of the clamping end 101 is consistent with the torch head of a plasma welding torch.

[0038] The first movable section 2 comprises water inlet I 203, water outlet I 204, air inlet II 205, gas distributor fixing hole I 206, cooling water closed flow storage circuit I 207, curved chute and connecting pivot hole; the water inlet I 203, water outlet I 204 and cooling water closed flow storage circuit I 207 constitute a circulating water circuit 1. The spatial pose of the fixed section and the movable section is flexibly adjusted through the connecting pivot I 201 and the curved chute I 202.

[0039] The second movable section 3 comprises water inlet II 303, water outlet II 304, air inlet III 305, gas distributor fixing hole II 306 and cooling water closed flow storage circuit II 307; the water inlet II 303, water outlet II 304 and cooling water closed flow storage circuit II 307 constitute a circulating water circuit 2. The spatial pose of the fixed section and the movable section is flexibly adjusted through the connecting pivot I 201 and the curved chute I 202. The reserved hole 308 is used for connecting the next movable section.

[0040] The two sides of the cooling water closed flow storage circuit of the circulating water circuit 1 and the circulating water circuit 2 are sealed through bolts and sealing rubber rings. The circulating water circuit is used for passing circulating cooling water to perform heat exchange.

[0041] Gas distributor: fixed below the fixed and movable joints; its interior is provided with a cavity 401, a fixed hole 402, and a gas distribution hole 403, the cavity 401 is communicated with the gas inlet I 104, the gas inlet II 205, and the gas inlet III 305, and the side wall is uniformly provided with a small gas outlet hole. The protective gas enters the cavity through the gas inlet, is buffered and uniformly distributed, and is uniformly sprayed from each gas outlet hole to form a protective gas curtain.

[0042] Example 1

[0043] A flexible inert gas protection device for pipe welding includes a fixed joint 1, a first movable joint 2, a second movable joint 3, and a gas distributor. The fixed joint 1 is detachably fixed to the plasma torch through the clamping end and the clamping tool fixing holes I 102 and II 103. The gas distributor 4 is fastened by screwing into the fixed hole 402 and the gas distributor fixing hole I 105 on the fixed joint 1, and the interior is provided with a cavity 401, the top is communicated with the gas inlet I 104, and the bottom and the side wall are uniformly distributed with five gas distribution holes 403 for uniformly distributing the protective gas. The first movable joint 2 is connected with the fixed joint 1 through the front end connecting pivot I 202, the connecting pivot I 202 penetrates the connecting pivot hole on the fixed joint and the movable joint, the curved sliding groove I 201 is adjusted to make the device meet the spatial position of the pipe, the curved sliding groove I 201 at the front end of the first movable joint 2 is fixed with the reserved hole at the rear end of the fixed joint 1 through a bolt, the water inlet I 203, the water outlet I 204, and the closed cooling water storage flow circuit I 207 form a circulating water circuit 1, the gas distributor 4 is located below the circulating water circuit 1, is fastened by screwing into the fixed hole 402 and the gas distributor fixing hole II 206 on the first movable joint 2, and the interior is provided with a cavity 401, the top is communicated with the gas inlet II 205, and the bottom and the side wall are uniformly distributed with five gas distribution holes 403 for uniformly distributing the protective gas. The circulating water circuit 1 plays a cooling role on the gas distributor 4, reducing the temperature of the protective gas. The second movable joint 3 is connected with the first movable joint 2 through the connecting pivot II 302, the curved sliding groove II 301 is adjusted to make the device meet the spatial position of the pipe, the curved sliding groove II 301 at the front end of the second movable joint 3 is fixed with the reserved hole at the rear end of the first movable joint 2 through a bolt, the water inlet II 303, the water outlet II 304, the gas inlet III 305, and the closed cooling water storage flow circuit II 307 form a circulating water circuit 2. The circulating water circuit 1 and the circulating water circuit 2 are respectively on the first movable joint 2 and the second movable joint 3, and the two sides of the closed cooling water storage flow circuit are sealed by a bolt and a sealing rubber ring. The gas distributor 4 is located below the circulating water circuit 2, is fastened by screwing into the fixed hole 402 and the gas distributor fixing hole III 306 on the second movable joint 3, and the interior is provided with a cavity 401, the top is communicated with the gas inlet III 305, and the bottom and the side wall are uniformly distributed with five gas distribution holes 403 for uniformly distributing the protective gas. The circulating water circuit 2 plays a cooling role on the gas distributor 4, reducing the temperature of the protective gas.

[0044] Example 2

[0045] The present embodiment uses a 304 stainless steel pipe with a thickness of 6 mm and a diameter of 219 mm as the welding object, and uses a plasma welding gun for welding. The test environment temperature is 25°C, the welding current is 200 A, and the welding speed is 120 mm / min.

[0046] (1) Installation and fixing device: connect the fixed section 1, the first movable section 2, and the second movable section 3, and install the gas distributor on the fixed section 1, the first movable section 2, and the second movable section 3 through bolts; connect the clamping tool fixing hole I 102 and the clamping tool fixing hole II 103 with the fixed clamp, clamp the plasma welding gun, and make the plasma welding gun head closely adhere to the clamping end 101; to enhance the protection effect of the device and reduce the interference to the pipe rotation, the position of the device should be slightly higher than the surface of the pipe, and the protection effect can be improved by wrapping fireproof tape;

[0047] (2) Adjust the movable section: according to the pipe diameter of 219 mm, adjust the position of the first movable section 2 by adjusting the curved chute I 201, and adjust the position of the second movable section 3 by adjusting the curved chute II 301, so that the gas distributor 4 of the fixed section 1, the first movable section 2, and the second movable section 3 is located directly above the post-welding area. Rotate the first movable section 2 clockwise by 20°, and rotate the second movable section 3 clockwise by 20°, to ensure that the gas distributor 4 is close to the post-welding area. After adjusting the movable section, the post-welding area protection length is 167 mm, and the distance from the weld height is 5 mm.

[0048] (3) Connect the water cooling system: connect the water outlet of the water cooling tank to the water inlet II 303, and the cooling water flows through the cooling water closed flow storage circuit II 307, backflows to the water outlet II 304, and the water outlet II 304 is connected to the water inlet I 203. The cooling water flowing into the water inlet I 203 flows through the cooling water closed flow storage circuit I 207, backflows to the water outlet I 104, and the water outlet I 104 is connected to the cooling water tank, forming an overall circulating water path. The circulating water flow is set to 2 L / min, and the water temperature is controlled at 20°C. The cooling water in the cooling water closed flow storage circuit I 207 and the cooling water closed flow storage circuit II 307 cools the device and the protective gas. As shown in Figure 4 , the red arrows mark the flow path of the cooling water in the circulating water paths 1 and 2;

[0049] (4) Introduce inert protective gas: connect the argon cylinder to the gas inlet I 104, the gas inlet II 205, and the gas inlet III 305 through pipelines, and set the gas flow to 10-20 L / min. As shown in Figure 4 , the red arrows mark the path of the protective gas entering from the fixed section and the movable section and being uniformly sprayed through the gas distributor.

[0050] Comparative Example 1

[0051] Using a rigid gas protection device with a fixed section suspended above the weld, the protection effect is the worst because the protection device cannot be effectively fitted to the weld.

[0052] Comparative Example 2

[0053] The flexible gas protection device is used, which differs from Example 2 in that the length of the protection device is 120mm and the height from the weld is 15mm. The other parameters and steps are the same as in Example 2. It can be seen that due to the insufficient protection length and the high distance from the weld, a more obvious oxidation phenomenon occurs at the weld.

[0054] Comparative Example 3

[0055] The flexible gas protection device is used. The difference from Example 2 is that the length of the protection device is 167mm and the height from the weld is 15mm. The other parameters and steps are the same as in Example 2. The length of the protection device is optimized. After keeping the height from the weld unchanged, the oxidation phenomenon is significantly improved and the weld shows a slight oxidation phenomenon.

[0056] Comparative Example 4

[0057] The flexible gas protection device is used, but the difference from Example 2 is that the length of the protection device is set to 167mm and the height from the weld is 10mm. The other parameters and steps are the same as in Example 2. The weld still shows a slight oxidation phenomenon, but the protection effect is improved by significantly reducing the height.

[0058] like Figure 5 The images shown are actual weld seams of the welded pipes of Examples 2 and Comparative Examples 1-4. From left to right, they are Comparative Examples 1-4 and Example 2. As can be seen from the images, Comparative Examples 1-4 all showed varying degrees of oxidation and yellowing, while the weld seam of Example 2 was silver. During the welding process, the metal was hardly oxidized, the weld metal was pure, there were no oxidation impurities, and the mechanical properties reached the optimal state.

[0059] In summary, the device of the present invention significantly improves the quality stability of pipe welding and extends the service life of the gas protection device through its flexible and adjustable structure, active water-cooled temperature control, and uniform gas distribution.

[0060] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A flexible inert gas shield for pipe welding, characterized in that The fixed joint includes a bottom pre-set hollow area, a movable joint, and a gas distributor in the hollow area; the hollow area is a cavity formed by the inward recess of the bottom of the fixed joint and the movable joint; The fixed joint includes a surface arranged gas inlet, a welding gun fixing hole I, and a welding gun fixing hole II; the clamping tool fixing hole I and the clamping tool fixing hole II are connected with the clamping tool, which can clamp the plasma welding gun, and the plasma welding gun is tightly attached to the clamping end of the fixed joint; The movable joint includes a surface arranged water inlet, water outlet, and gas inlet; the lower ends of the water inlet and the water outlet are respectively communicated with the horizontal section of the cooling water closed storage flow circuit of the bottom to form two outlet upward branches; the cooling water closed storage flow circuit is a hollow structure with an internal cavity, and the two ends thereof extend to the two side walls of the movable joint to form horizontal sections; the water inlet, the water outlet, and the cooling water closed storage flow circuit constitute a circulating water circuit; The gas distributor is connected with the fixed joint and the movable joint; the gas distributor is a closed structure with an internal cavity, a top surface provided with a hole communicated with the gas inlet, and two side walls provided with uniform holes; the protective gas entering the gas inlet is released from the holes in the two side walls of the gas distributor; The fixed joint and the movable joint are provided with a through connecting pivot at the bottom; the movable joint is provided with a curved sliding groove at the front end to adjust the angle between the fixed joint and the movable joint.

2. The flexible inert gas shield for tube welding according to claim 1, characterized in that The movable joint is provided with two or more movable joints, and the movable joints are provided with a through connecting pivot at the bottom; the curved sliding grooves at the front ends of the movable joints adjust the angle between the movable joints; the total protection length of the fixed joint and the movable joint is 160-200 mm.

3. The flexible inert gas shield for tube welding according to claim 1, characterized in that The movable joint rotates around the connecting pivot, and the clockwise rotation angle is 0-31°, and the counterclockwise rotation angle is 0-4°.

4. The flexible inert gas shield for tube welding according to claim 1, characterized in that The gas distributor is provided with a certain distance from the hollow area inner wall of the fixed joint and the movable joint; the distance is 5-15 mm; the diameter of the holes in the two side walls of the gas distributor is 2-5 mm.

5. The flexible inert gas shield for tube welding according to claim 1, characterized in that The fixed joint and the movable joint are coated with fireproof adhesive tape on the wall surface to prevent external air from penetrating into the protection area and the protective gas from spilling out of the gas distributor.

6. The flexible inert gas shield for tube welding according to claim 2, characterized in that The circulating water circuits of the movable joints are communicated to constitute an overall circulating water circuit.

7. The flexible inert gas shield for tube welding according to claim 1, characterized in that The surface shape of the clamping end of the front end of the fixed joint is the same as the shape of the torch head of the plasma welding gun, and the clamping end of the fixed joint can be tightly attached to the torch head of the plasma welding gun.

8. A method of protecting a flexible inert gas shield using the pipe welding flexible inert gas shield of any one of claims 1 to 7, characterized in that, The method comprises the following steps: Step 1: install the flexible inert gas protection device; after installation, the clamping tool of the fixed joint clamps the plasma welding gun, and the torch head of the plasma welding gun is tightly attached to the clamping end of the fixed joint; the flexible inert gas protection device is installed in the opposite direction of the welding direction; Step 2: according to the diameter and welding position of the pipe to be welded, the angle of the movable joint is adjusted by adjusting the sliding groove and the connecting pivot, so that the gas distributor is located directly above the post-welding area, and a certain distance is provided between the gas distributor of the fixed joint and the movable joint and the surface of the pipe and the distance is equal; Step 3: connect the cooling water to the overall circulating water circuit of the movable joint; connect the protective gas to the gas inlets of the fixed joint and the movable joint, and control the flow of the protective gas; Step 4: adjust the angle between the fixed joint and the movable joint by adjusting the sliding groove and the connecting pivot. Step 4: open the protective gas and cooling water before welding; the protective gas is delivered to the surface of the pipe through the internal passage of the device, and then the welding is started, and the protective gas forms a uniform protective gas curtain covering the high temperature area after welding after uniform flow; After the welding is completed, the protective gas and the cooling water are closed in turn.

9. The method of protecting a flexible inert gas shield for pipe welding according to claim 8, characterized in that, The distance between the protective device and the surface of the pipe to be welded is 3-8 mm.

10. The method of protecting a flexible inert gas shield for pipe welding according to claim 8, wherein The diameter of the pipe is 200-500 mm.

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