Local dry underwater laser welding multi-shielding gas filler wire drainage device

Abstract

The present invention provides a local dry underwater laser welding multi-shielding gas filler wire drainage device, comprising an adjustable straight pipe, a connecting module, a drainage cover, a nozzle, and a wire feeding pipe. The connecting module is provided with a welding shielding gas inlet hole; the connecting module, the adjustable straight pipe, and the nozzle are sequentially connected from top to bottom and jointly form a long straight through path; the welding shielding gas inlet hole is communicated with the long straight through path; the drainage cover is sleeved on the outer side of the adjustable straight pipe to form a drainage cavity having a downward opening; the drainage cover is provided with a drainage gas inlet hole, and the drainage gas inlet hole is communicated with the drainage cavity; a fixing channel is formed on one side of the drainage cover; the wire feeding pipe extends into the drainage cavity from the fixing channel; a third gap is formed between the inner wall of the fixing channel and the outer side of the wire feeding pipe; a welding wire shielding gas inlet hole is formed in the wall of the fixing channel; the welding wire shielding gas inlet hole is communicated with the drainage cavity by means of the third gap. The drainage device can satisfy the requirement of underwater filler wire laser welding, and relates to innovative use of welding wire shielding gas to ensure that welding wires are in a dry state, thereby effectively improving the quality of filler wire welding.

Description

Local dry method underwater laser welding multi-protection gas wire filling drainage device TECHNICAL FIELD

[0001] The present application relates to the technical field of underwater welding, more particularly to a local dry method underwater laser welding multi-protection gas wire filling drainage device. BACKGROUND

[0002] Ocean equipment is not only the key equipment to help the ocean economy, explore the marine environment, and exploit marine resources, but also an important engine to promote the overall progress of science and technology and the development of engineering application innovation. Due to the large load, high strength, extremely harsh environment and the influence of uncertain load such as wind and wave and earthquake, the key structural parts of ocean equipment are prone to damage, causing serious harm.

[0003] For the repair of marine structures, underwater welding repair technology is often used. Underwater laser welding technology has become a research hotspot due to its small water pressure influence, high energy density, and high control precision. Underwater laser welding technology is an ideal way for underwater welding repair operation. However, the existing underwater laser welding drainage device has the following problems:

[0004] (1) Poor quality of wire filling welding: the existing local dry method underwater laser welding drainage device does not consider the requirement of wire filling welding when designed. It has good effect when not filling wire, but the welding quality needs to be improved when using an external wire feeding device for underwater wire filling welding operation. The reasons for insufficient welding quality are that on the one hand, the welding wire will contact water, and water will also seep into the contact position of the welding wire and the drainage device, which will cause the temperature gradient of the molten pool to increase, resulting in poor welding quality. On the other hand, the external wire feeding device has insufficient adaptability with the drainage device, the dry extension of the welding wire is large, and the welding wire is unstable;

[0005] (2) Laser wire filling welding needs to ensure that the welding wire is in contact with the laser spot, otherwise it cannot effectively perform wire filling welding. The dry extension length of the external wire feeding device is large, which cannot effectively ensure the stable contact of the welding wire with the laser spot. The welding production efficiency is low because the welding operation needs to be adjusted frequently;

[0006] (3) In the actual welding process, the damage of the laser welding head protection lens is inevitable. The existing drainage device has a complex process and takes a long time to replace the protection lens, which also seriously affects the welding efficiency.

[0007] Therefore, the local dry method underwater laser welding process needs a drainage device that is more suitable for underwater wire filling welding and can obtain good welding quality. SUMMARY

[0008] In order to overcome the defects and deficiencies in the prior art, the purpose of the present application is to provide a local dry method underwater laser welding multi-protection gas wire filling drainage device; the drainage device can not only realize precise wire filling welding, but also innovatively uses protection gas to protect the welding wire, ensures that the welding wire is in a dry state, and can effectively improve the wire filling welding quality.

[0009] In order to achieve the above-mentioned purpose, the present application is realized by the following technical scheme: a local dry method underwater laser welding multi-protection gas wire filling drainage device, comprising an adjustable straight pipe, a connecting module, a drainage cover, a nozzle and a wire feeding pipe;

[0010] The connecting module is connected with the laser welding device; the connecting module is provided with a welding protection gas inlet hole for connecting with a welding protection gas conveying device; the connecting module, the adjustable straight pipe and the nozzle are coaxially connected from top to bottom in sequence and jointly form a long straight passage for the laser emitted by the laser welding device to pass through; the welding protection gas inlet hole is communicated with the long straight passage, so that the welding protection gas is input from the welding protection gas inlet hole, passes through the long straight passage and is then output from the nozzle outlet hole.

[0011] The drainage cover is sleeved outside the adjustable straight pipe and extends downward to a position below the bottom of the nozzle to form a downwardly open drainage cavity; the drainage cover is provided with a drainage gas inlet hole for connecting with a drainage gas conveying device, and the drainage gas inlet hole is communicated with the drainage cavity.

[0012] One side of the drainage cover is provided with a fixed channel; the wire feeding pipe extends into the drainage cavity from the fixed channel; a gap three is formed between the inner wall of the fixed channel and the outside of the wire feeding pipe; the fixed channel wall is provided with a welding wire protection gas inlet hole for connecting with a welding wire protection gas conveying device; the welding wire protection gas inlet hole is communicated with the drainage cavity through the gap three, so that the welding wire protection gas is input from the welding wire protection gas inlet hole, passes through the gap three and then enters the drainage cavity to form protection for the welding wire.

[0013] Preferably, the wire feeding pipe does not contact the nozzle; the center axis extension line of the wire feeding pipe intersects the center axis extension line of the long straight passage, and the intersection point is below the position of the bottom of the drainage cover.

[0014] Preferably, the included angle between the center axis extension line of the wire feeding pipe and the center axis extension line of the long straight passage is in the range of 25-35°.

[0015] Preferably, a boss is arranged outside the drainage cover; the drainage gas inlet hole is arranged in the boss; the drainage gas inlet hole is tangent to the circumferential inner wall cross section of the drainage cover and is inclined downward at an angle with the horizontal direction, so that the drainage gas forms a downward cyclone after entering the drainage cavity.

[0016] Preferably, annular micro gap two is formed between the drainage cover and the outer wall of the adjustable straight pipe.

[0017] Preferably, the connecting module is provided with a lens mounting groove; a lens pressing frame is detachably inserted in the lens mounting groove; the lens pressing frame is provided with a stepped ring; a protective lens is pressed in the stepped ring; and the protective lens is sealed by a sealing rubber ring at the joint with the stepped ring.

[0018] Preferably, the connecting module is provided with a uniform gas cavity; the welding protection gas inlet hole is arranged in the side wall of the uniform gas cavity; a uniform gas ring is arranged in the uniform gas cavity; an annular micro gap one is formed between the outer wall of the uniform gas ring and the side wall of the uniform gas cavity; the uniform gas ring is provided with a uniform gas ring inner hole; and the adjustable straight pipe is provided with a pipe hole.

[0019] The uniform gas ring inner hole, the pipe hole and the nozzle jet hole are sequentially communicated from top to bottom to form a long straight path for the laser emitted by the laser welding device to pass through; the welding protection gas is input from the welding protection gas inlet hole, is rectified into uniform annular high-pressure protection gas through the annular micro gap one, and then enters the long straight path formed by the uniform gas ring inner hole, the pipe hole and the nozzle jet hole from the space above the uniform gas ring, and is finally output from the nozzle jet hole.

[0020] Preferably, the annular micro gap one has a value range of 2% to 5% of the inner diameter of the uniform gas cavity.

[0021] Preferably, the adjustable straight pipe comprises an upper threaded pipe and a lower threaded pipe; the upper threaded pipe is screwed with the lower threaded pipe to realize the distance adjustment between the lens and the nozzle of the laser welding device by adjusting the screwing length of the upper threaded pipe and the lower threaded pipe; the screwing length between the upper threaded pipe and the lower threaded pipe is locked by a threaded locking ring; and the drain cover is arranged outside the lower threaded pipe.

[0022] Preferably, the top of the connecting module is provided with a connecting convex ring; the connecting convex ring is provided with a groove for mounting a sealing ring one; the drain cover and the lower threaded pipe are connected by a bolt, and a sealing ring two is arranged between the drain cover and the lower threaded pipe to realize sealing.

[0023] When the above drainage device is applied, the welding step is as follows:

[0024] First, adjust the drainage device to the welding position, so that the bottom of the drain cover does not directly contact the workpiece to be welded, and a space of 3-5 mm is reserved (determined according to the weld reinforcement); the welding direction should be that the laser spot points to the direction of the welding wire, that is, the welding wire is in front and the laser spot is behind during welding; the better relative position of the welding wire and the laser spot is that the welding wire points to the periphery of the laser spot without contacting the workpiece, and the welding wire and the workpiece maintain a space of 1 mm;

[0025] Secondly, the welding protection gas is introduced from the welding protection gas inlet hole into the space above the uniform gas ring to flush the protective lens first, and then is discharged along the light path through the inner hole of the uniform gas ring, the hole of the upper threaded tube, the hole of the lower threaded tube and the nozzle jet hole to produce the drainage effect; then the welding wire protection gas is introduced from the welding wire protection gas inlet hole to form a protective effect on the welding wire first; finally, the drainage gas is introduced to discharge the water in the drainage cavity to stabilize the dry space;

[0026] Then the laser beam is turned on, and about 0.1s after the laser beam is turned on, the welding wire is fed into the molten pool, and the drainage device is moved synchronously to start the welding operation.

[0027] Finally, when the welding is completed, the welding wire is stopped first, then the laser beam is turned off, the drainage device is moved out of the water, and then the drainage gas, the welding wire protection gas and the welding protection gas are turned off in sequence.

[0028] The pressure of the welding protection gas is slightly higher than that of the drainage gas and the welding wire protection gas; the gas backflow is prevented to cause water droplets or welding spatter to damage the lens of the laser welding device.

[0029] Compared with the prior art, the present application has the following advantages and beneficial effects:

[0030] 1. The drainage device of the present application can introduce the welding wire into the drainage cavity to meet the requirement of filler wire welding and innovatively use the welding wire protection gas; the welding wire may be in a non-dry state during underwater welding, which will reduce the heat input of welding and affect the welding efficiency; when the laser evaporates the liquid attached to the welding wire, water vapor will be generated to cause pores in the weld, which will reduce the welding quality; after the welding wire protection gas is introduced, a circular air flow is formed to ensure that the welding wire is in a dry state, prevent the welding wire from having a large temperature difference with the workpiece to affect the welding quality, and effectively improve the quality of filler wire welding.

[0031] 2. The drainage gas of the drainage device of the present application is innovatively blown downward along the inner wall of the drainage cover to form a downward cyclone; under the action of centrifugal force, the drainage gas expands outward along the axis to discharge the water and generate a stable dry space.

[0032] 3. According to the problem that the protective lens is inevitably damaged during actual laser welding, the present application designs a quick replacement structure of the protective lens to significantly improve the welding operation efficiency.

[0033] 4. The drainage device of the present application uses three gas paths for drainage; the welding protection gas is introduced from the welding protection gas inlet hole, flushed the protective lens first in the space above the uniform gas ring, and then discharged along the light path through the inner hole of the uniform gas ring, the adjustable straight tube hole and the nozzle jet hole; the drainage gas is introduced from the drainage gas inlet hole and then discharged through the drainage cavity; the welding wire protection gas is introduced from the welding wire protection gas inlet hole, enters the drainage cavity through the gap between the inner wall of the welding wire feeding tube and its fixed channel, and is finally discharged; the three gas paths effectively generate a local true dry environment suitable for laser filler wire welding.

[0034] 5、The gas path of the drainage device is very narrow, which can obtain low attenuation air pressure, is conducive to stable air flow, and prevents welding spatter from entering the gas path. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 is a schematic diagram of the structure of the partial dry underwater laser welding multi-protection gas wire filling drainage device according to the present application;

[0036] Figure 2 is an exploded view of the partial dry underwater laser welding multi-protection gas wire filling drainage device according to the present application;

[0037] Figure 3 is a schematic diagram of the welding protection gas path of the small-size partial dry underwater laser welding multi-protection gas wire filling drainage device according to the present application;

[0038] Figure 4 is a schematic diagram of the drainage gas path of the small-size partial dry underwater laser welding multi-protection gas wire filling drainage device according to the present application;

[0039] Figure 5 is a schematic diagram of the drainage gas path of the small-size partial dry underwater laser welding multi-protection gas wire filling drainage device according to the present application;

[0040] Figure 6 is a schematic diagram of the welding wire protection gas path of the small-size partial dry underwater laser welding multi-protection gas wire filling drainage device according to the present application;

[0041] Figures 7(a) to 7(c) are gas flow line simulation comparison diagrams of various blowing methods of drainage gas;

[0042] Among them, 1 is a connecting module, 2 is a lens pressing frame, 3 is a welding protection gas inlet hole, 4 is a uniform gas ring, 5 is an upper threaded pipe, 6 is a threaded locking ring, 7 is a lower threaded pipe, 8 is a nozzle, 9 is a drainage cover, 10 is a drainage gas inlet hole, 11 is a wire feeding pipe, and 12 is a welding wire protection gas inlet hole. DETAILED DESCRIPTION

[0043] The present application will be further described in detail below in combination with the drawings and specific embodiments.

[0044] EMBODIMENT

[0045] As shown in Figures 1 to 6, the partial dry underwater laser welding multi-protection gas wire filling drainage device according to the present embodiment includes an adjustable straight pipe, a connecting module 1, a drainage cover 9, a nozzle 8, and a wire feeding pipe 11. Among them, the adjustable straight pipe includes an upper threaded pipe 5 and a lower threaded pipe 7.

[0046] The connecting module 1 is connected with the laser welding device; the top of the connecting module 1 is provided with a connecting convex ring; the connecting convex ring is provided with a groove for mounting a sealing ring I. The connecting module 1 is provided with a lens mounting groove; a lens pressing frame 2 is detachably inserted in the lens mounting groove; the lens pressing frame 2 is provided with a stepped ring; a protective lens is pressed in the stepped ring; the protective lens is sealed by a sealing rubber ring at the joint with the stepped ring. The outer side of the lens pressing frame 2 is provided with two threaded holes, which are fixed with the lens mounting groove by two bolts, and the lens pressing frame 2 is also taken out from the lens mounting groove by the bolts.

[0047] The connecting module 1 is provided with a uniform gas cavity; the welding protection gas inlet hole 3 is arranged on the side wall of the uniform gas cavity; the uniform gas ring 4 is arranged in the uniform gas cavity; the annular micro gap I is formed between the outer wall of the uniform gas ring 4 and the side wall of the uniform gas cavity; the value range of the annular micro gap I is 2%-5% of the inner diameter of the uniform gas cavity. The uniform gas ring 4 is provided with a uniform gas ring inner hole; the annular micro gap I can rectify the bundled protective gas into uniform annular high-pressure protective gas and then deliver it to the uniform gas ring inner hole. The connecting module 1 is provided with a welding protection gas inlet hole 3 for connecting with the welding protective gas delivery device.

[0048] The upper threaded pipe 5 is screwed with the lower threaded pipe 7 to adjust the distance between the lens and the nozzle 8 of the laser welding device by adjusting the length of the screw connection between the upper threaded pipe 5 and the lower threaded pipe 7; the screw connection length between the upper threaded pipe 5 and the lower threaded pipe 7 is locked by the threaded locking ring 6; the drain cover 9 is sleeved on the outer side of the lower threaded pipe 7. The top end of the lower threaded pipe 7 is preferably provided with a threaded pipe sealing rubber ring groove, and a threaded pipe sealing rubber ring is used to prevent air leakage and water seepage. The adjustable straight pipe is provided with a pipe hole, which is composed of an upper threaded pipe hole and a lower threaded pipe hole.

[0049] The connecting module 1, the upper threaded pipe 5, the lower threaded pipe 7 and the nozzle 8 are coaxially connected from top to bottom; the uniform gas ring inner hole, the upper threaded pipe hole, the lower threaded pipe hole and the nozzle nozzle hole are sequentially communicated from top to bottom to form a long straight path for the laser emitted by the laser welding device to pass through; the welding protective gas is input from the welding protection gas inlet hole 3, rectified into uniform annular high-pressure protective gas by the annular micro gap I, and then enters the long straight path formed by the uniform gas ring inner hole, the upper threaded pipe hole, the lower threaded pipe hole and the nozzle 8 nozzle hole from the space above the uniform gas ring 4, and is output from the nozzle 8 nozzle hole.

[0050] The drain cover 9 is sleeved on the outer side of the adjustable straight pipe, specifically on the outer side of the lower threaded pipe 7 and extends downward to a position below the bottom of the nozzle 8 to form a downwardly open drain cavity; the drain cover 9 is provided with a drain gas inlet hole 10 for connecting with the drain gas delivery device, and the drain gas inlet hole 10 is communicated with the drain cavity. The drain cover 9 and the lower threaded pipe 7 are connected by bolts, and a sealing ring II is arranged between the drain cover 9 and the lower threaded pipe 7 to achieve sealing.

[0051] The protrusion is arranged outside the drain cover 9; the drain air inlet hole 10 is arranged in the protrusion; the drain air inlet hole 10 is preferably provided with an internal thread, facilitating connection with the air inlet pipe. The drain air inlet hole 10 is tangent to the circumferential inner wall of the drain cover 9, and is inclined downward at an angle with the horizontal direction, so as to form a downward cyclone after the drain gas enters the drain cavity. The drain cover 9 and the outer wall of the lower threaded pipe 7 form an annular micro gap two. The drain gas enters from the drain air inlet hole 10, enters the drain cavity through the annular micro gap two.

[0052] The nozzle 8 is connected with the lower threaded pipe 7 through an internal thread. The nozzle 8 is made of red copper material, which has good heat dissipation capacity. The nozzle 8 is wide at the top and narrow at the bottom, and has a certain length in the axial direction. The certain length and narrow flow channel are beneficial to stabilize the protective gas.

[0053] The minimum diameter of the nozzle 8 needs to be slightly larger than the size of the laser spot at the nozzle port when the extreme defocusing amount is reached. A smaller nozzle port size is beneficial to reduce the probability of welding spatter entering the light path, but an excessively small nozzle port size may cause the nozzle temperature to be too high, and even damage the nozzle.

[0054] The drain cover 9 is provided with a fixed channel on one side; the wire feeding pipe 11 extends into the drain cavity from the fixed channel, and is fixed by screwing the fixed channel. A gap three is formed between the inner wall of the fixed channel and the outer side of the wire feeding pipe 11; the fixed channel wall is provided with a welding wire protection air inlet hole 12 for connecting with the welding wire protection gas conveying device; the welding wire protection air inlet hole is communicated with the drain cavity through the gap three, so that the welding wire protection gas is input from the welding wire protection air inlet hole 12, and after passing through the gap three, it enters the drain cavity to form protection for the welding wire.

[0055] The wire feeding pipe 11 does not contact the nozzle 8; the center axis extension line of the wire feeding pipe 11 intersects with the center axis extension line of the long straight passage, and the intersection point is lower than the position of the bottom of the drain cover 9.

[0056] The included angle between the center axis extension line of the wire feeding pipe 11 and the center axis extension line of the long straight passage is in the range of 25-35°.

[0057] Fig. 7 (a)~Fig. 7 (c) are the simulation comparison diagrams of the gas flow lines of various blowing modes of the drainage gas; Fig. 7 (a) is the gas flow line under the blowing mode of the drainage gas adopted in the prior art, it can be seen that the flow is relatively chaotic after the drainage gas is blown, there are more turbulent flow phenomena, the unstable gas flow can seriously affect the drainage effect, and the chaotic flow of the drainage gas also has a certain influence on the stability of the molten pool, more welding spatters and weld porosity problems can be caused; Fig. 7 (b) is the drainage gas blown along the inner wall of the drainage cover in the tangential direction, the gas forms a cyclone after being blown, and there are only a few turbulent flow phenomena near the outlet of the drainage cover; Fig. 7 (c) is the blowing mode of the drainage gas adopted in the present application, the drainage gas is blown downward along the inner wall of the drainage cover at a certain angle with the horizontal direction, and the drainage gas forms a stable cyclone under this blowing mode, and no turbulent flow phenomenon occurs according to the simulation results.

[0058] When the above drainage device is applied, the welding steps are as follows:

[0059] Firstly, the drainage device is adjusted to the welding position, the bottom of the drainage cover 9 does not directly contact the workpiece to be welded, and 3~5 mm (determined according to the weld reinforcement) is reserved. The welding direction should be the direction in which the laser spot points to the welding wire, that is, when welding, the welding wire is in front and the laser spot is in back, and the better relative position of the welding wire and the laser spot is that the welding wire points to the periphery of the laser spot but does not contact the workpiece, and the welding wire and the workpiece maintain a space of 1 mm;

[0060] Secondly, the welding protection gas is introduced from the welding protection gas inlet hole 3, and then the space above the gas distribution ring 4 is flushed first, and then the gas is discharged along the light path through the inner hole of the gas distribution ring, the upper threaded tube hole, the lower threaded tube hole and the nozzle hole, so as to produce the drainage effect; then the welding wire protection gas is introduced from the welding wire protection gas inlet hole 12, and the welding wire is first protected; finally, the drainage gas is introduced, the drainage gas discharges the water in the drainage cavity, and a stable dry space is formed;

[0061] Then the laser beam is turned on, and after about 0.1 s of delay after the laser beam is turned on, the welding wire is started to be fed to the molten pool, and the drainage device is moved simultaneously to start the welding operation.

[0062] Finally, when the welding is completed, the welding wire is stopped first, and then the laser beam is turned off, the drainage device is moved out of the water, and then the drainage gas, the welding wire protection gas and the welding protection gas are turned off in sequence.

[0063] The pressure of the welding protection gas is slightly greater than that of the drainage gas and the welding wire protection gas; the gas backflow is prevented to cause the water droplets or welding spatters to damage the mirror of the laser welding device.

[0064] The drainage device of the present application can effectively drain water in a deep water environment, and the welding seam formed by the filler wire welding operation has good forming quality.

[0065] The above embodiments are the preferred embodiments of the present application, but the embodiments of the present application are not limited to the above embodiments, and any changes, modifications, substitutions, combinations, simplifications, etc. made without departing from the spirit and principles of the present application should be equivalent replacement manners and should be included in the protection scope of the present application.

Claims

1. A local dry underwater laser welding multi-shielding gas wire feeding drainage device, characterized in that: The adjustable straight pipe, the connecting module, the drain cover, the nozzle and the wire feeding pipe are included; The connecting module is connected with the laser welding device; the connecting module is provided with a welding protection gas inlet hole for connecting with a welding protection gas conveying device; the connecting module, the adjustable straight pipe and the nozzle are coaxially connected from top to bottom in sequence and jointly form a long straight passage for the laser emitted by the laser welding device to pass through; the welding protection gas inlet hole is communicated with the long straight passage so that the welding protection gas is input from the welding protection gas inlet hole, passes through the long straight passage and is then output from the nozzle outlet hole. The drain cover is sleeved outside the adjustable straight pipe and extends downward to a position below the bottom of the nozzle to form an open downward drain cavity; the drain cover is provided with a drain gas inlet hole for connecting with a drain gas conveying device, and the drain gas inlet hole is communicated with the drain cavity; One side of the drain cover is provided with a fixed channel; the wire feeding pipe extends into the drain cavity from the fixed channel; a gap three is formed between the inner wall of the fixed channel and the outer side of the wire feeding pipe; the fixed channel wall is provided with a welding wire protection gas inlet hole for connecting with a welding wire protection gas conveying device; the welding wire protection gas inlet hole is communicated with the drain cavity through the gap three so that the welding wire protection gas is input from the welding wire protection gas inlet hole, passes through the gap three and then enters the drain cavity to form protection for the welding wire.

2. The local dry underwater laser welding multi-gas-shielded wire-fed drainage device according to claim 1, characterized in that: The wire feeding pipe does not contact the nozzle; the center axis extension line of the wire feeding pipe intersects the center axis extension line of the long straight passage, and the intersection point is below the bottom of the drain cover.

3. The local dry underwater laser welding multi-gas-shielded wire- fed drainage device of claim 2, wherein: The included angle between the center axis extension line of the wire feeding pipe and the center axis extension line of the long straight passage is in the range of 25-35°.

4. The local dry underwater laser welding multi-gas-shielded wire-fed drainage device of claim 1, wherein: The outer side of the drain cover is provided with a boss; the drain gas inlet hole is arranged in the boss; the drain gas inlet hole is tangent to the cross section of the circumferential inner wall of the drain cover and is inclined downward at an included angle with the horizontal direction so that the drain gas forms a downward cyclone after entering the drain cavity.

5. The local dry underwater laser welding multi-gas-shielded wire- fed drainage device of claim 4, wherein: An annular micro gap two is formed between the outer wall of the drain cover and the outer wall of the adjustable straight pipe.

6. The local dry underwater laser welding multi-gas-shielded wire-fed drainage device of claim 1, wherein: The connecting module is provided with a lens mounting groove; a lens pressing frame is detachably inserted in the lens mounting groove; the lens pressing frame is provided with a stepped ring; a protective lens is pressed in the stepped ring; the cooperation part of the protective lens and the stepped ring is sealed by a sealing rubber ring.

7. The local dry underwater laser welding multi-gas-shielded wire-fed drainage device of claim 1, wherein: The connecting module is provided with a uniform gas cavity; the welding protection gas inlet hole is arranged in the side wall of the uniform gas cavity; a uniform gas ring is arranged in the uniform gas cavity; an annular micro gap one is formed between the outer wall of the uniform gas ring and the side wall of the uniform gas cavity; the uniform gas ring is provided with a uniform gas ring inner hole; the adjustable straight pipe is provided with a pipe hole; The uniform gas ring inner hole, the pipe hole and the nozzle outlet hole are sequentially communicated from top to bottom to form a long straight passage for the laser emitted by the laser welding device to pass through; the welding protection gas is input from the welding protection gas inlet hole, is rectified into uniform annular high-pressure protection gas through the annular micro gap one, enters the long straight passage formed by the uniform gas ring inner hole, the pipe hole and the nozzle outlet hole from the space above the uniform gas ring, and is then output from the nozzle outlet hole.

8. The local dry underwater laser welding multi-gas-shielded wire-fed drainage device according to claim 7, characterized in that: The annular micro gap one is in the range of 2%-5% of the inner diameter of the uniform gas cavity.

9. The local dry underwater laser welding multi-gas-shielded wire-fed drainage device of claim 1, wherein: The adjustable straight pipe comprises an upper threaded pipe and a lower threaded pipe; the upper threaded pipe is screwed with the lower threaded pipe to realize the adjustment of the distance between the lens and the nozzle of the laser welding device by adjusting the screwing length of the upper threaded pipe and the lower threaded pipe; the screwing length between the upper threaded pipe and the lower threaded pipe is locked by a threaded locking ring; a drain cover is sleeved outside the lower threaded pipe.

10. The local dry underwater laser welding multi-gas-shielded wire-fed drainage device of claim 9, wherein: The top of the connecting module is provided with a connecting convex ring; the connecting convex ring is provided with a groove for mounting a sealing ring one; the drain cover and the lower threaded pipe are connected by bolts, and the drain cover and the lower threaded pipe are provided with a sealing ring two for sealing.

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