A local vacuum laser welding device and welding method

Abstract

The application provides a local vacuum laser welding device and a welding method, which comprise a base, a welding table, a laser welding gun, a local sealing structure, a pressure assembly, a smoke protection assembly and a gas extraction pipeline, the pressure assembly and the welding table are arranged on the base, the pressure at the connection between the local sealing assembly and the welding table and a workpiece to be welded is changed, the smoke protection assembly is arranged between the laser welding gun and the local sealing structure, the laser welding gun is fixed relative to the local sealing assembly, and the local sealing assembly slides relative to the welding table. Through the arrangement of the local sealing assembly fixed relative to the laser welding gun and the welding table sliding relative to the local sealing assembly, the welding flexibility of a large-size structure is improved, the low vacuum degree of the whole welding process is ensured through the arrangement of the pressure assembly, the cleanliness of a lens during welding is ensured through the arrangement of the smoke protection assembly, and the welding efficiency of the large-size structure is improved while the welding quality is ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of non-ferrous metal welding, in particular to a local vacuum laser welding device and a welding method. BACKGROUND

[0002] Titanium alloy materials of large thickness are increasingly widely used, for example, a manned cabin spherical shell is a manned submersible, a deep-sea submersible, etc. For titanium alloy thick plate welding, laser welding can achieve good joint quality, but laser welding needs to be carried out in a vacuum chamber. Large titanium alloy structural members cannot be laser welded due to size limitations. The narrow gap welding method is widely used in titanium alloy thick plate narrow gap welding, but due to the large thickness, narrow gap welding needs to be carried out in multiple layers and multiple passes, and the welding efficiency is low. At the same time, the deformation control of thick plate welding is difficult, and it cannot meet the efficient welding of large structures.

[0003] In the 1980s, researchers proposed laser welding in a vacuum condition, which can improve the utilization rate of laser energy, increase the penetration ability of incident laser, and greatly increase the weld penetration. In recent years, with the emergence of high-power high-quality lasers, researchers have found that high-power lasers can also obtain large depth-to-width ratio welds similar to laser welding in a vacuum. Vacuum laser welding does not need to reach the extremely high vacuum required for laser welding. At the same time, there is no problem of atmospheric molecular scattering of electrons in laser welding, and there is also no need for radiation protection.

[0004] However, the vacuum degree of the welding area seriously affects the penetration of laser welding during the vacuum laser welding process, but in the existing technology, it is difficult to manufacture a vacuum space with sufficient vacuum degree on a large structure.

[0005] Chinese patent CN201921232451.2 discloses a local vacuum seal for laser welding. The sealing cover I includes a body I, and a vacuum groove I is arranged on the body I. The sealing cover II includes a body II, and a vacuum groove II and a mounting groove are arranged on the body II. The mounting groove and the vacuum groove II extend in the same direction and are in communication with each other, and the mounting groove is used for mounting a laser protection lens. The body I and the body II are respectively provided with air holes I and air holes II corresponding to the vacuum grooves I and II, respectively. A laser welding device includes a vacuum pumping system, a laser welding device, and the above-mentioned local vacuum seal. In use, the sealing cover I and the sealing cover II are used to be mounted on the two side surfaces of the plate to be welded, the vacuum grooves I and II are opposite to the joint, and then the vacuum pumping and laser welding operations are carried out. Although the patent can provide a vacuum space with better vacuum degree, the patent assembles a laser transmission lens along the weld which is equal in length to the weld, which has corresponding limitations on the length of the weld, cannot be used on large structures, and a large amount of smoke is generated during the welding process, which can easily cause the welding process to be unstable. SUMMARY

[0006] The problem solved by the present application is that in the prior art, it is difficult to manufacture a vacuum space with sufficient vacuum degree on a large structure, and the existing vacuum laser welding device cannot be used for large structures, and the smoke generated during welding easily leads to unstable welding process.

[0007] The present application discloses a kind of local vacuum laser welding device, comprising: pedestal, laser welding workpiece is formed on the pedestal above processing area;Welding table, the welding table is set on pedestal, the welding table at least includes first bearing plate, and the first bearing plate is used to fix the workpiece to be welded;Laser welding gun, the laser welding gun is set on the upper side of welding table, for welding workpiece to be welded;Local sealing structure, the local sealing structure is used to form local sealing welding area with workpiece to be welded and / or welding table, the local sealing structure, including sealing plate, first through hole is arranged at the center of the sealing plate, the laser of laser welding gun can pass through the first through hole and weld workpiece to be welded, the sealing plate is fixedly arranged relative to the laser welding gun, the local sealing structure can slide relative to welding table;Pressure assembly, the pressure assembly is fixedly arranged relative to the laser welding gun and sealing plate, for changing the pressure of the local sealing structure and the first bearing plate and / or workpiece to be welded junction;Smoke protection assembly, the smoke protection assembly is arranged between the laser welding gun and the local sealing structure, and lens is arranged on the upper side of the smoke protection assembly, and the laser generated by the laser welding gun is transmitted through the lens to weld workpiece to be welded;Exhaust pipeline, the exhaust pipeline is communicated with the inside chamber of sealing plate, and the exhaust pipeline is used to suck the air inside the local sealing structure to form a vacuum welding environment.

[0008] Further, the smoke protection assembly includes lens, gland, smoke protection cavity and gas resistance, the gland is used to seal the lens at the top end of the smoke protection cavity, and the gas resistance is arranged between the smoke protection cavity and the inside chamber of the sealing plate, and the gas resistance is used to block the smoke generated inside the local sealing structure during laser welding into the smoke protection cavity.

[0009] Further, the gas resistance includes support and baffle, first flange is arranged on the upper side of the support in a circumferential direction, sunken platform is arranged on the first through hole, the first flange is assembled with the sunken platform, the lower side of the support passes through the first through hole into the inside chamber of the sealing plate, second flange is arranged on the bottom of the support in a circumferential direction and is inwardly folded, the baffle is assembled with the second flange, light transmission hole is arranged on the baffle, and the laser generated by the laser welding gun is sequentially transmitted through the lens and the light transmission hole to weld workpiece to be welded.

[0010] Further, a boss is arranged at the bottom of the smoke protection cavity, the boss is matched and assembled with the sink, an annular groove is arranged on the boss, and the annular groove is used for arranging an air-tight element.

[0011] Further, an air inlet structure and an air extraction structure are arranged on the sidewall of the smoke protection cavity, the air inlet structure is used for filling inert gas into the smoke protection cavity, and the air extraction structure is used for extracting the inert gas in the smoke protection cavity.

[0012] Further, the pressure assembly comprises a first sliding plate, the first sliding plate is pressed on the upper side of the local sealing structure, guide columns are arranged at opposite ends of the first sliding plate, connecting sleeves are sleeved on the guide columns, the connecting sleeves are fixed on the base, a second sliding plate is arranged at the lower end of the guide column, the second sliding plate is integrated with the guide column, the second sliding plate can move up and down under the action of a second driving assembly, and the second driving assembly is fixed on the base.

[0013] Further, a back sealing structure is arranged on the first bearing plate, the back sealing structure is arranged on the first bearing plate through a first mounting groove on the first bearing plate, and a material pushing structure is arranged on the back sealing structure.

[0014] Further, first and second through holes are arranged on the sealing plate of the local sealing structure, a sealing assembly is arranged on the end of the sealing plate away from the laser welding gun, the first through hole is matched and assembled with the smoke protection assembly, the second through hole is connected with an air extraction pipeline, and a communication groove is arranged on the side of the sealing plate away from the laser welding gun, and the two ends of the communication groove are communicated with the first through hole and the second through hole, respectively.

[0015] Further, a first accommodating groove and a second accommodating groove are arranged on the side of the sealing plate away from the laser welding gun, the first and second accommodating grooves are both arranged in a closed ring shape, the center of the first accommodating groove and the center of the second accommodating groove coincide with the center of the sealing plate, the sealing assembly comprises first and second sealing rings, the second sealing ring is arranged in the first accommodating groove and is matched with the first accommodating groove in an interference fit, and the first sealing ring is arranged in the second accommodating groove and is matched with the second accommodating groove in an interference fit.

[0016] The application further discloses a welding method, which adopts the local vacuum laser welding device and comprises the following steps:

[0017] Step S1: processing a workpiece to be welded into an I-shaped groove, polishing the surface and the base material within 30 mm of the edge of the processed groove before assembly, cleaning and removing oil stains, and assembling and installing the processed workpiece to be welded on a welding table;

[0018] Step S2: using the pressure assembly to press the local sealing structure on the welding table, so that the sealing assembly is sealed with the workpiece and the welding table;

[0019] Step S3: vacuumizing the upper surface of the weld to ensure the vacuum degree of the environment during welding, and vacuumizing the back sealing structure on the back surface of the weld or using a protective cover to fill inert gas for protection;

[0020] Step S4: when the vacuum degree reaches the welding requirement, starting the laser welding gun to weld, the laser light passes through the lens and the smoke protection assembly in sequence and acts on the metal to be welded, the smoke protection assembly forms an air curtain through the flow of inert gas to prevent metal vapor from polluting the lens and ensure the light transmittance of the lens during welding; during welding, the vacuumizing system and the pressure assembly continuously run to ensure that the local sealing structure is sealed with the workpiece and the welding table;

[0021] Step S5: completing the welding.

[0022] Compared with the prior art, the local vacuum laser welding device and the welding method have the following advantages:

[0023] The local vacuum laser welding device and the welding method can realize welding of plate materials with a thickness of 2-3 times of the thickness of the laser welding under normal pressure by setting the welding table capable of moving relative to the laser welding gun and the local sealing device on the base; the strength coefficient of the titanium alloy joint reaches 0.95 or more, which is better than that of the laser welding under normal pressure; a high vacuum degree of 10 -2 Pa can be achieved, and the device is not limited by the structure and can slide along the weld, effectively solving the compatibility problems of the vacuum degree, flexibility and adaptability in welding large structures, and having high engineering application value. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is a schematic diagram of the local vacuum laser welding device according to the embodiment of the present application;

[0025] Figure 2 is a schematic diagram of the side view structure of the local vacuum laser welding device according to the embodiment of the present application;

[0026] Figure 3 is Figure 2 a schematic diagram of the cross-sectional structure of the A-A part;

[0027] Figure 4 is Figure 3 a local enlarged schematic diagram of the B part;

[0028] Figure 5 is a schematic diagram of the air resistance structure according to the embodiment of the present application;

[0029] Figure 6The explosion structure schematic view of the local vacuum laser welding device according to the embodiment of the present application;

[0030] Figure 7 The structure schematic view of the smoke protection assembly, the welding table and the pressure assembly assembled together according to the embodiment of the present application;

[0031] Figure 8 The structure schematic view of the smoke protection assembly, the welding table and the pressure assembly assembled together according to the embodiment of the present application;

[0032] Figure 9 The explosion structure schematic view of the smoke protection assembly, the welding table and the pressure assembly according to the embodiment of the present application;

[0033] Figure 10 The side view of the structure shown in the embodiment of the present application; Figure 9

[0034] Figure 11 The three-dimensional structure schematic view of the sealing plate according to the embodiment of the present application;

[0035] Figure 12 The three-dimensional structure schematic view of the sealing plate according to the embodiment of the present application;

[0036] Figure 13 The comparison view of the normal pressure laser welding joint and the local vacuum laser welding joint provided by the present application;

[0037] Figure 14 The state schematic view of the local vacuum laser welding device according to the embodiment 1 of the present application when welding a flat plate;

[0038] Figure 15 The state schematic view of the local vacuum laser welding device according to the embodiment 2 of the present application when welding a fillet weld.

[0039] Explanation of reference signs:

[0040] ​1, laser welding gun; 2, smoke protection assembly; 21, lens; 22, gland; 23, smoke protection cavity; 231, air inlet structure; 232, air extraction structure; 233, boss; 234, annular groove; 24, air resistance; 241, support; 2411, first folding edge; 2412, second folding edge; 242, baffle; 2421, light transmission hole; 3, local sealing structure; 31, sealing plate; 311, first through hole; 3111, sink; 312, second through hole; 313, communication groove; 314, first containing groove; 315, second containing groove; 32, sealing assembly; 321, first sealing ring; 322, second sealing ring; 4, welding table; 41, first bearing plate; 411, back sealing structure; 412, material lifting structure; 42, first driving assembly; 421, first driving motor; 422, speed reduction mechanism; 423, first mounting seat; 424, ball screw rod; 425, second mounting seat; 426, first nut sleeve; 427, second connecting plate; 428, shaft coupling; 429, first mounting groove; 43, sliding rail; 44, sliding block; 45, first connecting plate; 5, pressure assembly; 51, first sliding plate; 511, third through hole; 52, guide column; 53, connecting sleeve; 54, second sliding plate; 55, second driving assembly; 551, fixed frame; 552, second driving motor; 553, driving gear; 554, driven gear; 555, second ball screw; 556, third bearing seat; 557, second nut sleeve; 558, fourth bearing seat; 559, lifting connecting plate; 6, base; 61, support frame; 62, support panel; 621, track limiting groove; 622, connecting hole; 623, second mounting groove; 7, workpiece to be welded; 71, first workpiece; 72, second workpiece; 8, air extraction pipeline. DETAILED DESCRIPTION

[0041] To make the objectives, technical solutions, and advantages of the present application clearer, the following will further describe the present application with reference to the accompanying drawings and embodiments. It should be understood that the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. The specific embodiments described herein are merely used to explain the present application, and are not used to limit the present application. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0042] The following will specifically describe one local vacuum laser welding device and welding method according to an embodiment of the present application with reference to the accompanying drawings.

[0043] Embodiment 1

[0044] The present embodiment provides a local vacuum laser welding device, as shown in Figures 1-14 , comprising:

[0045] a base 6, a processing area of laser welding workpieces is formed above the base 6;

[0046] a welding table 4, the welding table 4 is arranged on the base 6, the welding table 4 at least includes a first bearing plate 41, the first bearing plate 41 is used for fixing a workpiece 7 to be welded;

[0047] a laser welding gun 1, the laser welding gun 1 is arranged on the upper side of the welding table 4, and is used for welding the workpiece 7 to be welded;

[0048] a local sealing structure 3, the local sealing structure 3 is used for forming a local sealing welding area with the workpiece 7 to be welded and / or the welding table 4, the local sealing structure 3 includes a sealing plate 31, a first through hole 311 is arranged at the center of the sealing plate 31, laser of the laser welding gun 1 can pass through the first through hole 311 to weld the workpiece 7 to be welded, and the sealing plate 31 is fixedly arranged relative to the laser welding gun 1; the local sealing structure 3 can slide relative to the welding table 4;

[0049] a pressure assembly 5, the pressure assembly 5 is fixedly arranged relative to the laser welding gun 1 and the sealing plate 31, and is used for changing the pressure at the connection between the local sealing structure 3 and the first bearing plate 41 and / or the workpiece 7 to be welded;

[0050] a smoke protection assembly 2, the smoke protection assembly 2 is arranged between the laser welding gun 1 and the local sealing structure 3, a lens 21 is arranged on the upper side of the smoke protection assembly 2, and laser generated by the laser welding gun 1 passes through the lens 21 to weld the workpiece 7 to be welded;

[0051] an air extraction pipeline 8, the air extraction pipeline 8 communicates with an inner chamber of the sealing plate 31, and the air extraction pipeline 8 is used for extracting air inside the local sealing structure 3 to form a vacuum welding environment.

[0052] The applicant found in the research process that for the local vacuum laser welding of large titanium alloy structures, the sealing performance of the welding space around the laser welding gun 1 is the most important for realizing the vacuum welding, but when the laser welding gun 1 forms a long weld on the workpiece 7 to be welded, the weld may need to pass through the local sealing structure 3, and the weld is extremely high in temperature after welding, and this structural change and high temperature environment is extremely easy to cause damage to the local sealing structure 3, thereby affecting the sealing performance of the welding space around the laser welding gun 1. The local vacuum laser welding device provided in the embodiment has two implementation forms, one is that the welding table 4 is relatively fixed with the base 6, and the laser welding gun 1, the local sealing structure 3 and the pressure assembly 5 are relatively moved with the welding table 4, and the other is that the laser welding gun 1, the local sealing structure 3 and the pressure assembly 5 are relatively fixed with the base 6, and the welding table 4 is relatively moved with the base 6, through the above setting, the relative movement of the laser welding gun 1 and the workpiece 7 to be welded is realized, and in the welding process, the pressure value applied by the pressure assembly 5 is adjusted according to the performance of the local sealing structure 3, so that the connection between the local sealing structure 3 and the first bearing plate 41 and / or the workpiece 7 to be welded is always kept in a relatively close and close state during the welding process, so as to avoid the sealing failure caused by the weld of the workpiece 7 to be welded after welding passing through the local sealing structure 3, thereby improving the efficiency and reliability of the laser welding gun 1, and the welding space is always in a space with relatively low vacuum degree, so that the local vacuum laser welding device provided in the embodiment is reliable in work when welding a large-size workpiece 7 to be welded, the volume of the vacuum chamber is not limited by the size of the laser welding part, the structure is ingenious, and the reliability of the application of the local vacuum laser welding technology is greatly improved. In the embodiment, the relative sliding between the local sealing structure 3 and the welding table 4 realizes the relative sliding between the local sealing structure 3 and the weld, so as to ensure the low vacuum degree and improve the size of the weldable weld, and the flexibility of welding is greatly improved. It should be noted that when the workpiece 7 to be welded is a flat plate, the first bearing plate 41 is also provided as a flat plate, and the upper surface of the first bearing plate 41 is relatively flush with the upper surface of the first bearing plate 41; when the workpiece 7 to be welded is an arc plate, the first bearing plate 41 is also provided as an arc plate, and the arc radius of the first bearing plate 41 is consistent with the workpiece 7 to be welded, so that when the workpiece 7 to be welded is arranged on the first bearing plate 41, the outer surface is combined into a unified arc surface structure, which can effectively ensure the sealing performance of the local sealing structure 3 at the gap between the workpiece 7 to be welded and the first bearing plate 41, so that the vacuum degree of the sealed welding area is kept stable during the welding process.

[0053] In the embodiment, as Figure 4 , Figure 5 , Figure 9As shown, the smoke protection assembly 2 comprises a lens 21, a gland 22, a smoke protection cavity 23 and a gas barrier 24, the gland 22 is used to seal the lens 21 at the top end of the smoke protection cavity 23, the gas barrier 24 is arranged between the smoke protection cavity 23 and the internal cavity of the sealing plate 31, and the gas barrier 24 is used to block the smoke generated in the local sealing structure 3 during laser welding from entering the smoke protection cavity 23.

[0054] During the laser welding process, especially the welding process of titanium alloy, a large amount of smoke will be generated, if the smoke enters the smoke protection cavity 23, the lens 21 will be seriously polluted, the light transmittance will be reduced, and the laser welding effect and efficiency will be poor, the arrangement of the gas barrier 24 greatly reduces the amount of smoke entering the smoke protection cavity 23, avoids the pollution of the lens 21, and effectively ensures the efficiency and quality of the laser welding.

[0055] As a preferred example of the present application, as Figure 5 As shown, the gas barrier 24 comprises a support 241 and a baffle 242, a first folded edge 2411 is arranged on the upper side of the support 241 in the circumferential direction, a sunken table 3111 is arranged on the first through hole 311, the first folded edge 2411 is matched and assembled with the sunken table 3111, the lower side of the support 241 penetrates through the first through hole 311 into the internal cavity of the sealing plate 31, a second folded edge 2412 is arranged on the bottom of the support 241 in the circumferential direction, the baffle 242 is matched and assembled with the second folded edge 2412, a light transmission hole 2421 is arranged on the baffle 242, and the laser generated by the laser welding gun 1 sequentially passes through the lens 21 and the light transmission hole 2421 to weld the workpiece 7 to be welded.

[0056] Through the above arrangement, the baffle 242 in the gas barrier 24 is closer to the weld, the closer the baffle 242 is to the weld, the better the suppression effect of the baffle 242 on the smoke generated during welding, and in addition, the light transmission hole 2421 is very small, so the smoke entering the smoke protection cavity 23 is limited, which can effectively prevent the lens 21 from being polluted, improve the welding quality and efficiency of the vacuum laser welding, and the structure of the first folded edge 2411 and the sunken table 3111 helps to form a sealing structure between the smoke protection assembly 2 and the local sealing structure 3, thereby further improving the vacuum degree in the local sealing structure 3 and improving the welding quality of the local laser welding. Optionally, the light transmission hole 2421 is a strip-shaped hole along the weld direction, which helps to increase the welding range of the laser welding gun 1.

[0057] In the embodiment, as Figure 4As shown, a boss 233 is arranged at the bottom of the smoke protection cavity 23, the boss 233 is matched and assembled with the sunken platform 3111, an annular groove 234 is arranged on the boss 233, and the annular groove 234 is used for arranging an air-tight member (not shown in the figure).

[0058] During assembly, the boss 233 is sleeved on the outer side of the first folded edge 2411 in the circumferential direction, and extends into the sunken platform 3111. Arranging the air-tight member in the annular groove 234 can significantly improve the air tightness of the smoke protection assembly 2 and the local sealing structure 3, and help to improve the vacuum degree of the internal cavity of the sealing plate 31, thereby improving the welding quality.

[0059] As a preferred embodiment, as shown in the figure, Figure 9 As shown, the gas inlet structure 231 and the gas extraction structure 232 are arranged on the side wall of the smoke protection cavity 23, the gas inlet structure 231 is used for filling inert gas into the smoke protection cavity 23, and the gas extraction structure 232 is used for extracting inert gas in the smoke protection cavity 23.

[0060] The arrangement of the gas inlet structure 231 and the gas extraction structure 232 can take away the smoke gas entering the smoke protection cavity 23, further avoiding pollution to the lens 21. In addition, the metal vapor during welding absorbs the laser beam and is ionized into a plasma cloud, which will consume the energy of the laser beam to a certain extent and affect the welding quality. The arrangement of the gas inlet structure 231 and the gas extraction structure 232 can effectively disperse the plasma cloud generated during laser welding, reduce the consumption of the laser by the plasma, and improve the quality of the laser welding. The gas extraction pipeline 8, the gas inlet structure 231 and the gas extraction structure 232 are always in working state during welding, so that the smoke gas and the plasma cloud generated during welding can be dispersed to the maximum extent, thereby ensuring the quality and efficiency of the laser welding.

[0061] As a preferred example of the present application, as shown in the figure, Figures 7-10As shown, the pressure assembly 5 includes a first sliding plate 51, which is pressed against the top of the partial sealing structure 3. Guide posts 52 are provided at opposite ends of the first sliding plate 51, and connecting sleeves 53 are sleeved on the guide posts 52. The connecting sleeves 53 are fixed on the base 6. A second sliding plate 54 is provided at the lower end of the guide posts 52. The second sliding plate 54 is integrated with the guide posts 52. The second sliding plate 54 can move up and down under the action of the second driving assembly 55, which is fixed on the base 6. As an example of the present invention, four guide posts 52 are provided, respectively arranged at the four azimuth angles of the first sliding plate 51. The upper and lower ends of the guide posts 52 are integrally connected to the first sliding plate 51 and the second sliding plate 54, respectively. Each guide post 52 passes through the support panel 62 of the base 6. Preferably, a connecting sleeve 53 is provided on each guide post 52, and a connecting hole 622 is provided on the support panel 62. The connecting sleeve 53 passes through the connecting hole 622 and is fixedly connected to the support panel 62. The second drive assembly 55 and the second sliding plate 54 are disposed inside the support frame 61 below the support panel 62. In use, when the second drive assembly 55 works, it drives the second sliding plate 54 to move up and down, thereby driving the guide posts 52 to move up and down as a whole. After passing through the connecting sleeve 53, the guide posts 52 drive the first sliding plate 51 to move up and down, changing the pressure borne by the local sealing structure 3 during welding. Optionally, a third through hole 511 is provided on the first sliding plate 51, and the dust protection component 2 passes through the third through hole 511 and is fixedly connected to the sealing plate 31.

[0062] The pressure component 5 of this invention has an ingenious structure. The second drive component 55 and most of the transmission device are housed inside the base 6, resulting in a more aesthetically pleasing appearance. This avoids the risk of noise or foreign object damage to the power unit of the pressure component 5 due to exposure, while also increasing the overall mass of the base 6. This improves the reliability of the pressure component 5 in changing the pressure at the connection point between the local sealing structure 3 and the first bearing plate 41 or the workpiece 7 to be welded, further enhancing the sealing performance of the internal space of the local sealing structure 3 during laser welding. This device is suitable for situations where the laser welding gun 1, the local sealing structure 3, and the pressure component 5 are fixed relative to the base 6, and the welding table 4 moves relative to the base 6. When the pressure component 5 is used in situations where the welding table 4 is fixed relative to the base 6, and the laser welding gun 1, the local sealing structure 3, and the pressure component 5 move relative to the welding table 4, the connecting sleeve 53 is movably connected to the base 6, and a drive component for sliding the pressure component 5 is provided on the base 6, allowing the pressure component 5 to slide relative to the base 6. Specific configurations can be based on existing technology and will not be elaborated here.

[0063] As a preferred example of the present application, as shown in Figure 10 The second driving assembly 55 includes a fixed frame 551 which is integrated with the base 6, a second driving motor 552 and a second ball screw 555 are arranged on the fixed frame 551, the second ball screw 555 is integrated with a second sliding plate 54 through a second nut sleeve 557, the upper and lower ends of the second ball screw 555 are connected with the fixed frame 551 through a third bearing seat 556 and a fourth bearing seat 558 respectively, and the second driving motor 552 is driven through meshing transmission gears with the second ball screw 555. As an example of the present application, the fixed frame 551 is arranged in a rectangular frame, the second driving motor 552 is fixed on the upper surface of the lower bottom plate of the fixed frame 551, the output shaft of the second driving motor 552 penetrates the lower bottom plate of the fixed frame 551, a driving gear 553 is fixed on the output shaft below the fixed frame 551, a driven gear 554 is arranged on the end of the second ball screw 555 which penetrates the lower bottom plate of the fixed frame 551, the driving gear 553 is meshed and driven with the driven gear 554, the third bearing seat 556 is arranged at the connection between the second ball screw 555 and the lower bottom plate of the fixed frame 551, the fourth bearing seat 558 is arranged on the lower surface of the upper plate of the fixed frame 551, the second ball screw 555 is rotationally connected with the third bearing seat 556 and the fourth bearing seat 558 through ball bearings, a lifting connecting plate 559 is arranged above the upper plate of the fixed frame 551, and the lifting connecting plate 559 is used to fixedly connect the fixed frame 551 with the base 6. As a preferred example, two lifting connecting plates 559 are arranged. In use, the second driving motor 552 drives the driving gear 553 to rotate, and the second ball screw 555 is driven to rotate in the opposite direction through the external meshing action of the driving gear 553 and the driven gear 554. Since the second ball screw 555 is connected with the fixed frame 551 through the third bearing seat 556 and the fourth bearing seat 558, the second ball screw 555 can only rotate, and the second nut sleeve 557 arranged on the second ball screw 555 drives the second sliding plate 54 to move up and down integrally.

[0064] The arrangement discloses a structure of the second driving assembly 55, which drives the second sliding plate 54 to move up and down integrally through the ball screw, has reasonable structure, realizes continuous adjustment of the pressure applied by the pressure assembly 5 on the local sealing structure 3, and further improves the smoothness and reliability of the working of the pressure assembly 5.

[0065] As a preferred example of the present application, as shown in Figure 6As shown, the welding table 4 further comprises a first driving assembly 42 fixedly arranged relative to the base 6, the first driving assembly 42 being configured to drive the first carrying plate 41 to move. When the workpiece 7 to be welded is a flat plate, the first driving assembly 42 is configured to drive the first carrying plate 41 to move horizontally, and when the workpiece 7 to be welded and the first carrying plate 41 are arc-shaped, the first driving assembly 42 is configured to drive the first carrying plate 41 to rotate about the center axis of the arc shape.

[0066] The arrangement only needs to move the welding table 4 to realize the movement of the weld relative to the laser welding gun 1, and the synchronous movement device structure of the laser welding gun 1, the smoke protection assembly 2, the local sealing structure 3, and the pressure assembly 5 is simpler, and the welding position of the workpiece 7 to be welded is moved by arranging the welding table 4. In the welding process, the pressure value of the pressure assembly 5 is adjusted according to the performance of the local sealing structure 3, so that the connection between the local sealing structure 3 and the first carrying plate 41 and / or the workpiece 7 to be welded is always kept in a relatively close state during the welding process, avoiding the sealing failure caused by the weld of the workpiece 7 to be welded passing through the local sealing structure 3, thereby improving the efficiency and reliability of the laser welding gun 1. It should be noted that corresponding driving structures can also be arranged to drive the synchronous horizontal movement of the laser welding gun 1, the smoke protection assembly 2, the local sealing structure 3, and the pressure assembly 5 (the workpiece 7 to be welded is a flat plate), or to drive the laser welding gun 1, the smoke protection assembly 2, the local sealing structure 3, and the pressure assembly 5 to rotate about the center axis of the arc shape of the workpiece 7 to be welded (the workpiece 7 to be welded is an arc-shaped plate).

[0067] As an example of the present application, as Figure 3 As shown, the first driving assembly 42 comprises a first driving motor 421 configured to drive a ball screw 424 to rotate, the ball screw 424 being bearing-connected with a first mounting seat 423 and a second mounting seat 425, the first mounting seat 423 and the second mounting seat 425 being integrated with a support panel 62 of the base 6, the ball screw 424 being screw-driven with a first nut sleeve 426, the first nut sleeve 426 being integrated with the first carrying plate 41 through a second connecting plate 427, wherein the rotating center axis direction of the ball screw 424 is vertically arranged relative to the rotating center axis direction of the second ball screw 555.

[0068] The setting discloses a structure that the first driving assembly 42 drives the first bearing plate 41 to move horizontally, optimizes the driving and transmission structure of the welding table 4, reasonably utilizes the space inside and on the base 6, and guarantees the reliability of the movement of the workpiece 7 to be welded and the local vacuum laser welding. It should be understood that other driving structures can also be used to realize the horizontal movement or rotation of the welding table 4, which will not be described here.

[0069] As a preferred example of the present application, as shown in Figure 7 The welding table 4 further comprises a sliding rail 43 and a sliding block 44, the sliding block 44 is connected with the first bearing plate 41 through a first connecting plate 45, and the sliding block 44 can slide on the sliding rail 43. As a preferred example, two sets of sliding rails 43 and sliding blocks 44 are provided correspondingly, and the two sliding rails 43 are arranged on opposite sides of the ball screw 424.

[0070] The setting further improves the smoothness and reliability of the horizontal movement of the first bearing plate 41 under the action of the first driving assembly 42 through the guiding and sliding action of the sliding block 44 and the sliding rail 43.

[0071] As a preferred example of the present application, a speed reduction mechanism 422 and a shaft coupling 428 are arranged between the first driving motor 421 and the ball screw 424. In use, the output shaft of the first driving motor 421 is connected with the end of the ball screw 424 through the speed reduction mechanism 422 and the shaft coupling 428. Through the speed reduction action of the speed reduction mechanism 422, the transmission torque of the ball screw 424 is improved, so that the first bearing plate 41 can still move horizontally reliably and smoothly when the local sealing structure 3 is subjected to a higher pressure. The output end of the speed reduction mechanism 422 is connected with the ball screw 424 through the shaft coupling 428, which guarantees the concentricity when the output shaft of the first driving motor 421, the output shaft of the speed reduction mechanism 422 and the ball screw 424 are driven, and further improves the reliability of the work of the first driving assembly 42.

[0072] As a preferred example of the present application, as shown in Figure 3As shown, the back sealing structure 411 is arranged on the first bearing plate 41, and the back sealing structure 411 is arranged on the first bearing plate 41 through the first mounting groove 429 on the first bearing plate 41, and the back sealing structure 411 is provided with a top material structure 412. As preferred, the back sealing structure 411 comprises a downwardly recessed accommodating space, and the first workpiece 71 and the second workpiece 72 of the workpiece to be welded 7 are spliced to form a welding seam in the first mounting groove 429, and the welding seam is opposite to the laser output by the laser welding gun 1, and when the workpiece to be welded 7 moves integrally with the first bearing plate 41 under the action of the first driving assembly 42, the plane of the workpiece to be welded 7 is flush with the upper surface of the first bearing plate 41 or forms a unified arc surface structure, thereby realizing reliable welding of the workpiece.

[0073] In the welding process of titanium alloy, the weld is exposed to air, which is prone to hydrogen embrittlement and oxidation discoloration, which seriously affects the welding quality. The back sealing structure 411 is used to seal the back of the workpiece to be welded 7, so as to avoid oxidation during welding. Preferably, inert gas is filled in the back sealing structure 411 during welding, thereby forming good protection. Since the upper surface of the workpiece to be welded 7 is flush with the upper surface of the first bearing plate 41 or forms a unified arc surface structure, it is not easy to take out after welding, and the arrangement of the top material structure 412 helps to take out the welded workpiece after welding, thereby improving the work efficiency.

[0074] As a preferred example of the present application, the base 6 comprises a support frame 61 and a support panel 62, the support panel 62 is fixed above the support frame 61, a connecting hole 622 is arranged on the support panel 62, the connecting hole 622 is arranged corresponding to the connecting sleeve 53; a second mounting groove 623 is arranged on the support panel 62, the second mounting groove 623 is used to install the first driving motor 421 and / or the speed reduction mechanism 422. As preferred, a box cover plate is arranged inside or outside the support frame 61, and a counterweight is arranged inside the support frame 61 to increase the overall mass of the base 6. As preferred, a track limiting groove 621 is arranged on the upper surface of the support panel 62, and the track limiting groove 621 is used to place the sliding rail 43.

[0075] Through the second mounting groove 623 arranged on the support panel 62, the relative mounting height of the first driving assembly 42 is adjusted, so as to provide space for the first bearing plate 41 to install different back sealing structures 411, thereby further improving the local vacuum laser welding device of the present application to be applicable to welding of various large-sized parts.

[0076] The above embodiment is mainly used for disclosing the smoke protection assembly 2 and the driving system and transmission system in the local vacuum laser welding device, by arranging the air resistance 24 and the smoke protection cavity 23, the smoke pollution of the lens 21 during welding is avoided, so that the welding quality and welding efficiency of the laser welding are improved, and by arranging the mutually perpendicular ball screw rod 424 and the second ball screw 555, on the one hand, the pressure applied by the pressure assembly 5 to the local sealing structure 3 can be continuously adjusted according to the structure and performance of the local sealing structure 3, the sealing of the connection between the local sealing structure 3 and the first bearing plate 41 or the workpiece 7 to be welded is ensured, even when the high-temperature weld passes through, the sealing reliability of the welding space inside the local sealing structure 3 is still ensured, the low-vacuum environment requirement of the laser welding gun 1 during welding is ensured, and on the other hand, the workpiece 7 to be welded can be reliably moved horizontally relative to the local sealing structure 3 under the action of the driving device, the structure is ingenious, the space inside the base 6 and the platform upper plate is reasonably utilized, and the reliability of the welding table 4 and the pressure assembly 5 during work and the smoothness of the movement adjustment are ensured.

[0077] It should be noted that, as shown in Figure 15 , the welding device provided by the application is also used for welding of fillet welds, and in the specific welding process, a laser welding gun 1, a local sealing structure 3, a pressure assembly 5, a smoke protection assembly 2, and an air exhaust pipeline 8 are arranged on both sides of the T-shaped vertical plate respectively, and synchronous welding from both sides of the fillet weld can be achieved, and in this process, two laser welding guns 1, two local sealing structures 3, two pressure assemblies 5, two smoke protection assemblies 2, and two air exhaust pipelines 8 are used, and a back sealing structure 411 is used.

[0078] As a preferred example of the application, as shown in Figure 11 , Figure 12 , the sealing plate 31 of the local sealing structure 3 is provided with a first through hole 311 and a second through hole 312, a sealing assembly 32 is arranged on one end of the sealing plate 31 away from the laser welding gun 1, the first through hole 311 is sealingly assembled with the smoke protection assembly 2, the second through hole 312 is connected with the air exhaust pipeline 8, and a communication groove 313 is arranged on one side of the sealing plate 31 away from the laser welding gun 1, and the two ends of the communication groove 313 are respectively communicated with the first through hole 311 and the second through hole 312.

[0079] This arrangement improves the structure of the local sealing structure 3, on the one hand, ensures the reliability of the local vacuum laser welding in the sealing space inside the local sealing structure 3, and on the other hand, avoids the pollution of the smoke to the lens 21 during welding through the smoke protection assembly 2, and ensures the welding quality.

[0080] As a preferred example of the present application, a first accommodating groove 314 and a second accommodating groove 315 are arranged on the side of the sealing plate 31 away from the laser welding gun 1, the first accommodating groove 314 and the second accommodating groove 315 are both arranged in a closed ring shape, and the center of the first accommodating groove 314, the center of the second accommodating groove 315 and the center of the sealing plate 31 coincide, the sealing assembly 32 comprises a first sealing ring 321 and a second sealing ring 322, the second sealing ring 322 is arranged in the first accommodating groove 314, the second sealing ring 322 is in interference fit with the first accommodating groove 314, and the first sealing ring 321 is arranged in the second accommodating groove 315, and the first sealing ring 321 is in interference fit with the second accommodating groove 315.

[0081] The local vacuum laser welding device of the present application adopts a sealing assembly 32 which is a high-temperature sealing material for local vacuum laser welding developed by the applicant, the high-temperature sealing material can withstand a temperature of 500 DEG C and has a hardness of less than 20, so that the sealing assembly 32 can be prevented from being burned when relative movement occurs with the weld during welding, and also has good elastic deformation capacity, so that the local sealing structure 3 is always kept in a low vacuum state, and the vacuum degree can reach 10 - 2 Pa, and the penetration capacity of laser welding reaches 2-3 times of the same power in a normal pressure environment.

[0082] The components of the sealing assembly 32 of the present application include (by mass fraction):

[0083] Zinc oxide 3-8 parts, stearic acid 0.5-3 parts, carbon black 10-50 parts, antioxidant 0.5-3 parts, sulfur 0-2 parts, accelerator 1-5 parts, plasticizer 5-20 parts, foaming agent 1-10 parts, and silicon nitride 0-20 parts.

[0084] The rubber matrix is at least one of ethylene-vinyl acetate copolymer, ternary ethylene-propylene rubber and silicone rubber.

[0085] In the present embodiment, the carbon black is at least one of carbon black N330, carbon black N550 and carbon black N990.

[0086] As a preferred example of the present application, the antioxidant is at least one of antioxidant 4010NA, antioxidant MB and antioxidant RD.

[0087] As a preferred example of the present application, the plasticizer is at least one of plasticizer TP-95, plasticizer DOP and plasticizer DOS.

[0088] As a preferred example of the present application, the foaming agent is at least one of foaming agent AC and foaming agent OBSH.

[0089] The preparation method of the material comprises the following steps:

[0090] ST1: Strictly weigh the raw materials of the sealing material for the local vacuum laser welding;

[0091] ST2: The prepared raw materials are subjected to a plasticizing process of an open mill, a mixing process of a banbury mixer, a mixing process of an open mill and an extrusion molding process.

[0092] As an example of the present application, the plasticizing process of the open mill comprises the following steps:

[0093] ST211: The base rubber is subjected to plasticizing on a double-roller open mill, the roller gap is adjusted to the minimum, and the rubber is passed through N times;

[0094] ST212: The roller gap is adjusted to be larger, and M triangle packs are punched;

[0095] wherein N and M are preset parameters.

[0096] Specifically, as an example of the present application, the base rubber is subjected to sufficient plasticizing on a double-roller open mill, the roller gap is adjusted to the minimum, and the rubber is passed through 6-8 times, and the roller gap is adjusted to be larger, and 6-8 triangle packs are punched.

[0097] As a preferred example of the present application, the mixing process of the banbury mixer comprises the following steps:

[0098] ST221: The plasticized base rubber, zinc oxide and anti-aging agent are put into the banbury mixer, the rotor speed is controlled to be 20-40 rpm, the preset mixing time T1 is controlled, and the temperature is controlled to be below 80℃;

[0099] ST222: The plasticizer, half of the carbon black and half of the foaming agent are added into the banbury mixer, the rotor speed is controlled to be 20-40 rpm, the preset mixing time T2 is controlled, and the temperature is controlled to be below 80℃;

[0100] ST223: The other half of the carbon black and the other half of the foaming agent are added into the banbury mixer, the rotor speed is controlled to be 20-40 rpm, the preset mixing time T3 is controlled, and the temperature is controlled to be below 80℃;

[0101] wherein the preset time T1, the preset time T2 and the preset time T3 are preset time parameters, and T1≤T2 and T1≤T3. As a preferred example, T2=T3. As an example of the present application, T1=2 minutes, T2=3 minutes and T3=3 minutes.

[0102] As an example of the present application, the mixing process of the open mill comprises the following steps:

[0103] ST231: After the rubber material is mixed out of the banbury mixer, the rubber material is placed in a ventilated place for cooling;

[0104] ST232: open the cooling water of the open mill, and sequentially add small materials including accelerators and sulfur on the device;

[0105] ST233: after the re-mixing of the small materials is completed, increase the roll gap and perform three triangle bag Q passes, wherein Q is a preset parameter;

[0106] ST234: after the surface of the rubber material is smooth and has no obvious bubbles, the sheet is discharged, and the mixing process is completed.

[0107] Specifically, as an example of the present application, after the rubber material is mixed out of the mixing chamber, it is taken to a well-ventilated place for sufficient cooling, the cooling water of the open mill is opened, and small materials such as accelerators and sulfur are sequentially added on the device. After the re-mixing of the small materials is completed, increase the roll gap and perform three triangle bag 4-5 passes, until the surface of the rubber material is smooth and has no obvious bubbles, the sheet is discharged, and the mixing process is completed.

[0108] As an example of the present application, the extrusion molding process includes the following steps:

[0109] ST241: cool the prepared rubber material;

[0110] ST242: the extruder is divided into multiple heating sections, and the temperature of each heating section gradually decreases from front to back, and the pulling speed is B, wherein B is a preset parameter;

[0111] ST243: place the rubber material on the conveyor belt of the extruder, and cool the extruded sample through the cooling device.

[0112] Specifically, as an example of the present application, the prepared rubber material is cooled, the extruder is divided into four heating sections, and the heating temperatures are set to 160°C, 150°C, 145°C and 140°C, respectively. The pulling speed is 1.6 mm / s. Then the rubber material is placed on the conveyor belt of the extruder, and the extruded sample is cooled through the cooling device. Finally, a sealing material with low hardness and high temperature resistance as shown in Figure 1 、 Figure 2 is prepared.

[0113] Through the above preparation method, a sealing material with low hardness (hardness less than 20) and high temperature resistance (500°C) in a short time can be obtained, which can be applied to local vacuum laser welding.

[0114] Specifically, the rubber material formula of the sealing material for local vacuum laser welding according to the present application is shown in Table 1 below:

[0115] Table 1: Sealing material formula example

[0116]

[0117] The components are weighed according to the above rubber formulation, and then the sealing material prepared from the mixing rubber is prepared according to the preparation method of the sealing material for the local vacuum laser welding.

[0118] Embodiment 2

[0119] The embodiment provides a welding method for the local vacuum laser welding device as described in the embodiment, and the welding method comprises the following steps:

[0120] Step S1: process the workpiece to be welded into an I-shaped groove, polish the surface and the base material within 30 mm of the edge of the processed groove before assembly, then clean and remove oil stains, and assemble and install the processed workpiece to be welded on the welding table;

[0121] Step S2: press the local sealing structure on the welding table by using the pressure assembly, so that the sealing assembly is attached and sealed with the workpiece and the welding table;

[0122] Step S3: vacuumize the upper surface of the weld to ensure the vacuum degree of the environment during welding, or vacuumize the back sealing structure on the back surface of the weld or use a protective cover to fill inert gas for protection;

[0123] Step S4: when the vacuum degree meets the welding requirements, start the laser welding gun to perform welding, and the laser light acts on the metal to be welded after passing through the lens and the smoke protection assembly in sequence, and the smoke protection assembly forms an air curtain by flowing of the inert gas to prevent the metal vapor from polluting the lens and ensure the light transmittance of the lens during welding; during the welding process, the vacuum system and the pressure assembly continuously operate to ensure that the local sealing structure is attached and sealed with the workpiece and the welding table;

[0124] Step S5: complete the welding.

[0125] The high-adaptability local vacuum laser welding device and the welding method for large structures provided in the embodiment can be applied to welding of metal structures such as titanium alloy, steel and aluminum alloy.

[0126] The welding strength coefficient of the titanium alloy workpiece joint manufactured by using the local vacuum laser welding device provided in the embodiment 1 and the welding method provided in the embodiment 2 is not less than 0.95.

[0127] Embodiment 3

[0128] The embodiment provides a welding example performed by using the local vacuum laser welding device described in the embodiment 1 and the welding method provided in the embodiment 2, and the material is a ship Ti80 alloy, which is widely used on deep submersibles and ship equipment, and has a high requirement on impact toughness in a service environment.

[0129] The forming raw material is a Ti80 titanium alloy plate, and the thickness of the test plate is 42 mm. The surface of the Ti80 titanium alloy base plate is mechanically polished, and then cleaned by ultrasonic cleaning with acetone and alcohol solvents to remove oil stains, and dried for use. After measuring the size of the cleaned workpiece, it is placed on the workbench and fixed with a clamp. Local vacuum laser welding device and method are used for welding, with a welding speed of 0.6-1.5 m / min, a laser power of 16-20 KW, and a vacuum degree of 10-1000 Pa. The entire laser welding process is carried out in a local vacuum environment, and the surface of the welded test plate does not oxidize, and the surface of the formed component is silver-white or light yellow.

[0130] After welding, the local vacuum laser welded joint completed according to the above steps is detected by an X-ray detector, and the weld quality meets the requirements of NB 47013-2015 I level. The joint structure is analyzed by a metallographic microscope, the tensile test of the welded joint is tested by an electronic universal testing machine, and the impact toughness of the joint is tested by a pendulum impact tester.

[0131] The local vacuum laser welding of Ti80 alloy is carried out by the present application, and the penetration thickness is about 3 times that of ordinary laser welding, and the welded joint has no nail tip defect, and the welded joint is compared as shown in FIG. 1. Figure 15 In addition, the local vacuum laser welding of Ti80 alloy can obtain good joint performance, and the tensile strength coefficient reaches 99%, and the impact absorption energy is higher than that of the base material, as shown in Table 2.

[0132] Table 2 Joint performance of local vacuum laser welded Ti80 alloy

[0133]

[0134] In addition to the welding thickness and performance being better than that of the ordinary pressure laser welded joint, the local vacuum laser welding method of the present application can realize efficient laser welding of large structures, and has important significance and application prospect in the field of ships and deep sea equipment.

[0135] It should be noted that all the terms indicating direction and position in the present application, such as "upper", "lower", "left", "right", "front", "back", "vertical", "horizontal", "inner", "outer", "top", "low", "tail end", "head end", "center", etc. are only used to explain the relative position relationship, connection condition, etc. between components in a certain state, and are only for the convenience of describing the present application, and thus cannot be understood as a limitation on the present application that it must be constructed and operated in a particular orientation. In addition, the description of "first", "second", etc. in the present application is only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. In addition, the meaning of "and / or" appearing throughout the text includes three parallel schemes. For example, "A and / or B" includes A scheme, or B scheme, or A and B simultaneously.

[0136] In the present application, unless otherwise explicitly specified and limited, the terms "connection", "fixation", etc. should be understood broadly, for example, "fixation" can be fixed connection, or detachable connection, or integral; can be mechanical connection, or electrical connection; can be direct connection, or indirect connection through an intermediate medium; can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise explicitly limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0137] Although the present application is disclosed as above, the present application is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present application, and thus the protection scope of the present application should be subject to the scope defined by the claims.

Claims

1. A local vacuum laser welding method using a local vacuum laser welding device, characterized by, The local vacuum laser welding device comprises: a base (6) on which a processing area for laser welding workpieces is formed; a welding table (4) provided on the base (6), the welding table (4) comprising at least a first bearing plate (41) for fixing a workpiece (7) to be welded; a laser welding gun (1) provided on the upper side of the welding table (4) for welding the workpiece (7) to be welded; a local sealing structure (3) for forming a local sealing welding area with the workpiece (7) to be welded and / or the welding table (4), the local sealing structure (3) comprising a sealing plate (31) provided with a first through hole (311) at the center of the sealing plate (31), the laser of the laser welding gun (1) being capable of passing through the first through hole (311) to weld the workpiece (7) to be welded, the sealing plate (31) being fixedly arranged relative to the laser welding gun (1), and the local sealing structure (3) being capable of sliding relative to the welding table (4); a pressure assembly (5) fixedly arranged relative to the laser welding gun (1) and the sealing plate (31) for changing the pressure at the connection between the local sealing structure (3) and the first bearing plate (41) and / or the workpiece (7) to be welded; a smoke protection assembly (2) provided between the laser welding gun (1) and the local sealing structure (3), the upper side of the smoke protection assembly (2) being provided with a lens (21), and the laser generated by the laser welding gun (1) passing through the lens (21) to weld the workpiece (7) to be welded; an air extraction pipeline (8) in communication with the inner chamber of the sealing plate (31), the air extraction pipeline (8) being used for extracting air inside the local sealing structure (3) to form a vacuum welding environment; the smoke protection assembly (2) comprising the lens (21), a gland (22), a smoke protection cavity (23) and a gas resistance (24), the gland (22) being used for sealingly arranging the lens (21) at the top end of the smoke protection cavity (23), the gas resistance (24) being arranged between the smoke protection cavity (23) and the inner chamber of the sealing plate (31), and the gas resistance (24) being used for blocking smoke generated inside the local sealing structure (3) during laser welding from entering the smoke protection cavity (23). The air block (24) comprises a support (241) and a baffle (242), a first folded edge (2411) is arranged on the upper side of the support (241) in the circumferential direction, a sunken platform (3111) is arranged on the first through hole (311), the first folded edge (2411) is matched and assembled with the sunken platform (3111), the lower side of the support (241) penetrates through the first through hole (311) into the internal cavity of the sealing plate (31), a second folded edge (2412) is arranged on the bottom of the support (241) in the circumferential direction and is inwardly folded, the baffle (242) is matched and assembled with the second folded edge (2412), a light transmission hole (2421) is arranged on the baffle (242), and the laser generated by the laser welding gun (1) sequentially penetrates through the lens (21) and the light transmission hole (2421) to weld the workpiece (7) to be welded; An air inlet structure (231) and an air extraction structure (232) are arranged on the side wall of the smoke protection cavity (23), the air inlet structure (231) is used for filling inert gas into the smoke protection cavity (23), and the air extraction structure (232) is used for extracting inert gas in the smoke protection cavity (23); The pressure assembly (5) comprises a first sliding plate (51), the first sliding plate (51) is pressed on the upper side of the local sealing structure (3), guide columns (52) are arranged at opposite ends of the first sliding plate (51), connecting sleeves (53) are sleeved on the guide columns (52), the connecting sleeves (53) are fixed on the base (6), a second sliding plate (54) is arranged at the lower end of the guide column (52), the second sliding plate (54) is integrated with the guide column (52), the second sliding plate (54) can move up and down under the action of a second driving assembly (55), and the second driving assembly (55) is fixed on the base (6); A back sealing structure (411) is arranged on the first bearing plate (41), the back sealing structure (411) is arranged on the first bearing plate (41) through a first mounting groove (429) on the first bearing plate (41), and a material pushing structure (412) is arranged on the back sealing structure (411); The welding method comprises the following steps: Step S1: processing the workpiece to be welded into an I-shaped groove, polishing the surface and the base material within 30 mm of the edge of the processed groove before assembly, cleaning and removing oil stains, and assembling and installing the processed workpiece to be welded on the welding table; Step S2: pressing the local sealing structure on the welding table by using the pressure assembly, so that the sealing assembly is attached and sealed with the workpiece and the welding table; Step S3: vacuumizing the upper surface of the weld to ensure the vacuum degree of the environment during welding, and vacuumizing the back sealing structure on the back surface of the weld or using a protective cover to fill inert gas for protection. Step S4: when the vacuum degree reaches the welding requirement, start the laser welding gun to weld, the laser acts on the metal to be welded after passing through the lens and the smoke protection assembly in turn, the smoke protection assembly forms an air curtain through the flow of inert gas to prevent metal vapor from polluting the lens and ensure the light transmittance of the lens during welding; during welding, the vacuum system and the pressure assembly continue to run to ensure the sealing between the local sealing structure and the workpiece and the welding table; Step S5: complete the welding.

2. The local vacuum laser welding method of claim 1, wherein, A boss (233) is arranged at the bottom of the smoke protection cavity (23), the boss (233) is matched and assembled with the sink (3111), an annular groove (234) is arranged on the boss (233), and the annular groove (234) is used to arrange a gas seal.

3. The local vacuum laser welding method of claim 1, wherein, The sealing plate (31) of the local sealing structure (3) is provided with a first through hole (311) and a second through hole (312), a sealing assembly (32) is arranged on one end of the sealing plate (31) away from the laser welding gun (1), the first through hole (311) is sealingly assembled with the smoke protection assembly (2), the second through hole (312) is connected with the gas extraction pipeline (8), a communication groove (313) is arranged on one side of the sealing plate (31) away from the laser welding gun (1), and the two ends of the communication groove (313) are respectively communicated with the first through hole (311) and the second through hole (312).

4. The local vacuum laser welding method of claim 3, wherein, A first containing groove (314) and a second containing groove (315) are arranged on one side of the sealing plate (31) away from the laser welding gun (1), the first containing groove (314) and the second containing groove (315) are both arranged in a closed ring shape, the center of the first containing groove (314) and the center of the second containing groove (315) coincide with the center of the sealing plate (31), the sealing assembly (32) comprises a first sealing ring (321) and a second sealing ring (322), the second sealing ring (322) is arranged in the first containing groove (314), the second sealing ring (322) is in interference fit with the first containing groove (314), the first sealing ring (321) is arranged in the second containing groove (315), and the first sealing ring (321) is in interference fit with the second containing groove (315).

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