Anti-deformation welding tool and method for large 3D printing closed cavity thin-wall part

Abstract

The invention discloses a large 3D printing closed cavity thin-wall part anti-deformation welding tool and method.The tool comprises a top-layer circular ring, a middle-layer circular ring and a base, S1, a thin-wall cavity part model is subjected to support adding and blank allowance supplementing, and a closed cavity structure is provided with a window used for removing supports; s2, preparing raw materials; s3, equipment is started, and 3D printing of the thin-wall cavity part is carried out; s4, the thin-wall cavity part obtained after 3D printing is subjected to solution treatment; through 3D printing, production of the annular thin-wall part with the closed inner cavity is achieved, and the weight of the part is greatly reduced; the designed welding tool is matched with the inner wall of the part in shape, the inner wall is fixed, and welding deformation is prevented; according to the designed double-person symmetrical back welding method, the heat input amount is controlled to be distributed in the radial direction of the annular thin-wall part, and therefore shrinkage deformation caused by welding thermal stress is reduced; the problem that a component of a large closed cavity structure manufactured through a single 3D printing process cannot be formed through a conventional method that a support is added and then removed is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of laser additive manufacturing, and specifically relates to a large-scale 3D printed closed cavity thin-walled part anti-deformation welding tool and method. Background Art

[0002] With the acceleration of the pace of space exploration, aerospace engines have higher requirements for lightweight, high-strength, low-cost, rapid prototyping, green environmental protection technology and high-temperature comprehensive performance of structural materials, and technical and engineering research needs to be carried out as soon as possible. By adopting advanced manufacturing technology and effective structural topology optimization design, it is an inevitable trend for future development to achieve lightweight aerospace structures and materials while ensuring structural performance. At the same time, due to the continuous improvement of aerospace vehicle's requirements for material performance, the continuous complexity of material structures, and the long production cycle, high cost, and low efficiency of traditional manufacturing processes such as casting, forging, and rolling, they can no longer meet the needs and challenges of aerospace vehicles such as multiple models, multiple batches, ultra-precision, and fast response. Therefore, realizing the integration of design and manufacturing of complex and difficult-to-process structural parts, shortening the development cycle, and reducing development costs are the keys to the rapid development of aerospace equipment.

[0003] Lightweight complex structure laser additive manufacturing is a core technology in the field of aerospace manufacturing. 3D printing technology is the key to achieve lightweight, integrated, high-performance manufacturing of key aerospace components. Among them, the laser selective melting forming process is the most prominent, which can realize the integrated forming of complex thin-walled structures, but for closed cavity structure components, it is impossible to achieve forming by the conventional method of adding supports and then removing them. Especially for thin-walled cavity components with functional cooling air film hole structure characteristics, the single use of 3D printing or traditional manufacturing process technology cannot meet the manufacturing needs. Therefore, the present invention innovatively proposes a large-scale 3D printed closed cavity thin-walled parts anti-deformation welding tooling and method, combining welding with 3D printing technology to achieve the purpose of composite manufacturing. Summary of the invention

[0004] The purpose of the present invention is to provide a large-scale 3D printed closed cavity thin-walled parts anti-deformation welding tool and method to solve the problems raised in the above background technology.

[0005] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a large-scale 3D printed closed cavity thin-walled part anti-deformation welding tool, the tool comprises a top ring, a middle ring, and a base from top to bottom, and the top ring, the middle ring, and the base are connected by a plurality of columns to form a main frame, a circle of bottom sector blocks with slidable inner diameters are installed on the base through fastening bolts, and a bottom cam lock for driving the bottom sector blocks to expand is rotatably installed on the base through a cam lock stud, and the middle ring is provided with a bottom cam lock for driving the bottom sector blocks to expand. A middle sector block with a slidable inner diameter size is installed by fastening bolts, and a middle cam lock for driving the middle sector block to expand is rotatably installed on the middle circular ring through a cam lock stud. A top sector block with a slidable inner diameter size is installed on the top circular ring by fastening bolts, and a top cam lock for driving the top sector block to expand is rotatably installed on the top circular ring through a cam lock stud. The top cam lock, the middle cam lock and the bottom cam lock are all provided with positioning locking threaded columns for limiting their own rotation.

[0006] Preferably, a pair of lifting rings are symmetrically arranged on the top of the base, and the lifting rings are screwed to the base; the bottom of a circle of the middle fan-shaped blocks are connected to parts protection gaskets through screws, and the top fan-shaped blocks, the middle fan-shaped blocks and the bottom fan-shaped blocks are all provided with strip guide grooves that cooperate with the corresponding fastening bolts.

[0007] A large-scale 3D printed closed cavity thin-walled part anti-deformation welding method, using the tooling, specifically comprising: S1: adding support to the thin-walled cavity part model, supplementing the blank margin, and opening a window for removing support in the closed cavity structure;

[0008] S2: Raw material preparation, using metal alloy powder with a powder particle size of 15-53μm;

[0009] S3: Start the equipment to perform 3D printing of thin-walled cavity parts;

[0010] S4: heat treatment of the thin-walled cavity parts after 3D printing;

[0011] S5: Separate the substrate and the thin-walled cavity part by wire cutting, fix the removed thin-walled cavity part on a vise, and remove the support on the part with a rubber hammer and chisel;

[0012] S6: Dimensional inspection and non-destructive testing of thin-walled cavity parts;

[0013] S7: Fixing the thin-walled cavity component using the tooling;

[0014] S8: Most of the through holes of the thin-walled cavity are blocked, leaving only two holes, one hole for introducing argon gas and the other hole for discharging argon gas, so as to form a protective gas circulation;

[0015] S9: Place the thin-walled cavity parts into the tooling for sealing plate welding;

[0016] S10: After welding, stress relief annealing is performed on the weld position of the thin-walled cavity part;

[0017] S11: After welding, perform non-destructive testing on the weld and perform dimensional testing on the entire structure.

[0018] Preferably, in S1, in order to achieve rigidity and lightweight design, the thin-walled cavity part has an annular cavity structure, and support needs to be added in the cavity to ensure that the upper wall does not collapse during printing. For this reason, 16 evenly distributed strip windows need to be opened for a whole circle of the cavity structure during model processing to facilitate the removal of support; in S2, when preparing raw materials, it is necessary to check and record the brand, quantity, specification, and batch number information of the metal alloy powder. After verification, a sufficient amount of metal powder is added to the equipment material chamber with a shovel. The diameter of the cavity thin-walled part is greater than 1000mm, and the brand of the metal alloy powder can be nickel-based high-temperature alloy, cobalt-based high-temperature alloy, titanium alloy, aluminum alloy, steel, etc.

[0019] In S3, the laser power, scanning speed, scanning spacing, and powder layer thickness process parameters should be strictly controlled; turn on the argon gas, set the air intake pressure to 0.5MPa, turn on the ventilation cycle, water cooling, scanning galvanometer, and laser, and when the oxygen content reaches below 1000ppm, the equipment automatically starts the printing process; after the forming is completed, the equipment automatically stops printing, and the part can be taken out when the substrate temperature drops below 40°C; during the entire process of taking out the parts, the explosion-proof vacuum cleaner is turned on to absorb the floating dust in the forming chamber in time; during the printing process, 16 windows need to be corresponding The sealing plate is printed together with the furnace; during the printing process, the mechanical properties test bars and test plates should be prepared with the furnace; in the S4, when performing heat treatment, the vacuum degree, temperature, insulation time, cooling method process parameters are strictly controlled; under the condition that the vacuum degree P value is less than 10Pa, the temperature is heated from room temperature to 260℃-950℃ at a specific heating rate, and the temperature is kept for 1-4h. After the temperature is completed, 1000-1500mbar argon is filled for rapid cooling, and the furnace temperature drops to room temperature; the vacuum pressure should be less than 5×10 -2 Pa.

[0020] In S6, non-destructive testing should include penetration testing and X-ray testing. When conducting penetration testing, the appearance should be free of cracks and pores; when conducting X-ray testing, the internal quality should be free of cracks, unfused parts, and dense pores. Other quality requirements should comply with the specified technical conditions and acceptance conditions; dimensional detection adopts three-dimensional scanning.

[0021] Preferably, in S7, the tooling materials are all nickel-based high-temperature alloys, which are also printed through steps S1-S5 and non-destructively tested through step S6 to ensure that the linear expansion coefficient of the tooling is consistent with that of the thin-walled cavity parts, so as to facilitate welding and stress relief annealing after welding. The tooling can restrain the thin-walled cavity parts; the thin-walled cavity parts are inserted into the main frame from top to bottom, and the top cam lock, the middle cam lock and the bottom cam lock are rotated in turn to push the top fan-shaped blocks, the middle fan-shaped blocks and the bottom fan-shaped blocks outward respectively, so that the outer sides of the fan-shaped blocks are conformed to the inner walls of the thin-walled cavity parts, and then the corresponding cam locks are locked by positioning and locking threaded columns to achieve reverse deformation of the cavity parts; the parts protection gaskets added on the platform can prevent the platform and the bolts from direct contact to cause extrusion and damage to the parts; when the welding is completed, the parts are lifted together with the tooling through the lifting rings and put into the heat treatment equipment.

[0022] Preferably, in S9, before welding, it should be checked whether the surfaces of the parts and welding wire are cleaned, whether all the knobs on the welding machine panel are in the preset positions, whether the valve of the argon gas bottle is in the open state, and whether the argon gas circulation is unobstructed; the through holes of the parts are sealed with high-temperature tape, and the inner cavity is inflated to protect the back during welding. The argon gas flow rate before welding is not less than 15L / min, and the argon filling time is not less than 15min. The back gas protection argon gas flow rate during welding is 5L / min-15L / min. The welding process is: welding current 35A-5 0A, welding speed 3-10mm / s, argon gas flow rate 10L / min-15L / min; mark the area to be welded, a total of 16 areas, area 1 is opposite to area 2, area 1 is 90° counterclockwise to area 3, area 3 is opposite to area 4, area 5 is on the left of area 1, and areas 5-16 are marked in the same way; the gap between the thin-walled cavity part and the sealing plate is 0.1-0.8mm, spot welding is used for positioning first, and after positioning welding, check that there is no obvious misalignment in the welded joint; a two-person symmetrical back-welding method is used.

[0023] Preferably, when performing stress relief annealing in S10, the tooling and parts are put into a vacuum furnace as a whole; the vacuum degree, temperature, holding time, and cooling method process parameters are strictly controlled; under the condition that the vacuum degree P value is less than 10Pa, the temperature is heated from room temperature to 200°C-850°C at a specific heating rate, and after holding for 1-4h, 1000-1500mbar argon is filled for rapid cooling, and the furnace temperature drops to room temperature; the vacuum pressure during heating to above 500°C, during the holding process, and before the argon is filled should be less than 5×10 - 2 Pa.

[0024] Preferably, the nondestructive testing in step S11 should include penetration testing and X-ray testing. When performing penetration testing, the appearance should be free of cracks and pores; when performing X-ray testing, the internal quality should be free of cracks, unfused areas, and dense pores, and the remaining quality requirements should meet the specified technical conditions and acceptance conditions; dimensional detection adopts three-dimensional scanning, and after the scanning, the figure needs to be fitted with the data recorded in step S6 and the deviation is compared. The dimensional deviation should meet the requirements specified in the part drawing of ±1.0mm.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] (1) The present invention replaces the traditional casting method through 3D printing, realizes the production of annular thin-walled parts with a closed inner cavity, greatly reduces the weight of the parts, and also reduces the production cost and cycle, thereby realizing low-cost and rapid manufacturing of this type of parts;

[0027] (2) The inner cavity support is removed by welding the strip window and the sealing plate; the present invention designs a set of welding tooling with a layered structure, which pushes the fan-shaped block outward by a cam lock, and the outer side of the fan-shaped block follows the shape of the inner wall of the part to fix the inner wall and prevent welding deformation;

[0028] (3) The present invention designs a two-person symmetrical desoldering method to control the heat input to be distributed radially along the annular thin-walled part, thereby reducing the shrinkage deformation caused by welding thermal stress, and the shrinkage deformation is controlled within ±0.6 mm;

[0029] (4) The present invention can be applied to a variety of combined manufacturing methods. The combination of laser selective melting forming method and any one of laser welding / electron beam welding / plasma welding can achieve the composite manufacturing of annular thin-walled parts with closed inner cavities.

[0030] (5) The present invention can be applied to 3D printing of large annular thin-walled parts with closed inner cavities using metal alloy powders such as nickel-based / cobalt-based high-temperature alloys, titanium alloys, aluminum alloys, and steel, with guaranteed dimensional accuracy and quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the tooling structure of the present invention;

[0032] Figure 2 It is a schematic diagram of the tooling explosion structure of the present invention;

[0033] Figure 3 This is a schematic diagram of the welding position of the sealing plate of the present invention;

[0034] Figure 4 is a schematic diagram of the inner cavity structure of the present invention;

[0035] Figure 5 It is a schematic diagram of a welding sample of the present invention;

[0036] In the figure: 1. top-layer fan-shaped block; 2. top-layer cam lock; 3. fastening bolt; 4. cam lock stud; 5. middle-layer cam lock; 6. column; 7. middle-layer ring; 8. middle-layer fan-shaped block; 9. parts protection gasket; 10. bottom-layer cam lock; 11. bottom-layer fan-shaped block; 12. base; 13. lifting ring; 14. top-layer ring. DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] Example 1

[0039] See also Figures 1 to 5, which is the first embodiment of the present invention, and this embodiment provides a technical solution: a large-scale 3D printed closed cavity thin-walled component anti-deformation welding tool, the tool includes a top ring 14, a middle ring 7, and a base 12 from top to bottom, and the centers of the top ring 14, the middle ring 7, and the base 12 coincide with each other, and the top ring 14, the middle ring 7, and the base 12 are connected by a plurality of columns 6 to form a main frame, and the columns 6 are provided with external threads and nuts for fixing, so that the top ring 14, the middle ring 7, and the base 12 are stably installed, and a circle of bottom sector blocks 11 with an inner diameter that can be slidably adjusted is installed on the base 12 through fastening bolts 3, and a bottom cam lock 10 that drives the bottom sector block 11 to expand is rotatably installed on the base 12 through a cam lock stud 4, and the bottom sector block 11 can be expanded outward by rotating the bottom cam lock 10, so that the cavity thin-walled component is fitted, and the middle ring 7 is fastened by the fastening screw The bolt 3 is equipped with a circle of middle-layer sector blocks 8 whose inner diameter can be slidably adjusted. The middle-layer cam lock 5 for driving the middle-layer sector block 8 to expand is rotatably installed on the middle-layer circular ring 7 through the cam lock stud 4. By rotating the middle-layer cam lock 5, the middle-layer cam lock 5 pushes the middle-layer sector block 8 to expand outward so as to fit the thin-walled part of the cavity. A circle of top-layer sector blocks 1 whose inner diameter can be slidably adjusted is installed on the top-layer circular ring 14 through the fastening bolt 3. The top-layer cam lock 2 for driving the top-layer sector block 1 to expand is rotatably installed on the top-layer circular ring 14 through the cam lock stud 4. By rotating the top-layer cam lock 2, the cam structure on the top-layer cam lock 2 pushes the top-layer sector block 1 outward to expand. The top-layer cam lock 2, the middle-layer cam lock 5 and the bottom-layer cam lock 10 are all provided with positioning locking threaded columns for limiting their own rotation, so that after the expansion and fitting of each sector block is completed, it is locked and positioned by its own positioning locking threaded columns to prevent the sector blocks from moving again. In this embodiment, preferably, a pair of lifting rings 13 are symmetrically arranged on the top of the base 12 for lifting the entire tooling, and the lifting rings 13 are screwed together with the base 12 through threads; flexible installation and disassembly can be achieved, and the bottom of a circle of middle fan-shaped blocks 8 are connected with parts protection gaskets 9 through screws to prevent the platform and the bolts from directly contacting and squeezing to cause damage to the parts; the top fan-shaped block 1, the middle fan-shaped block 8 and the bottom fan-shaped block 11 are all provided with strip guide grooves that match the corresponding fastening bolts 3 to play a guiding sliding role.

[0040] A large-scale 3D printed closed cavity thin-walled part anti-deformation welding method, using tooling, the specific method includes: S1: adding support to the thin-walled cavity part model, supplementing the blank margin, and opening a window for removing the support in the closed cavity structure; in this embodiment, preferably, in S1, in order to achieve rigidity and lightweight design, the thin-walled cavity part has an annular cavity structure, such as Figure 1As shown; support needs to be added in the cavity to ensure that the upper wall does not collapse during printing. For this reason, 16 evenly distributed strip windows need to be opened in a whole circle of cavity structure during model processing to facilitate support removal;

[0041] S2: Raw material preparation, using nickel-based high-temperature alloy powder, the powder particle size is 15-53 μm; in this embodiment, preferably, in step S2, when preparing the raw materials, it is necessary to check and record the brand, quantity, specification, and batch number of the nickel-based high-temperature alloy powder. After checking, use a shovel to add a sufficient amount of metal powder into the equipment material cabin. The diameter of this cavity thin-walled part is 1148 mm;

[0042] S3: Start the equipment to perform 3D printing of thin-walled cavity parts; in this embodiment, preferably, in S3, the laser power, scanning speed, scanning spacing, and powder layer thickness process parameters should be strictly controlled; turn on the argon gas, set the air intake pressure to 0.5MPa, turn on the ventilation cycle, water cooling, scanning galvanometer, and laser, and when the oxygen content reaches below 1000ppm, the equipment automatically starts the printing process; after the forming is completed, the equipment automatically stops printing, and the part removal operation can be performed when the substrate temperature drops below 40°C; during the entire process of taking out the parts, the explosion-proof vacuum cleaner is turned on to absorb the floating dust in the forming chamber in time; During the printing process, the sealing plates corresponding to the 16 windows need to be printed together with the furnace; during the printing process, mechanical property test bars and test plates should be prepared along with the furnace; in S4, when performing solution treatment, the vacuum degree, temperature, insulation time, and cooling method process parameters are strictly controlled; under the condition that the vacuum degree P value is less than 10Pa, it is heated from room temperature to 950℃±10℃ at a specific heating rate, and after the insulation is completed, 1000-1500mbar argon is filled for rapid cooling, and the furnace temperature drops to room temperature; the vacuum pressure should be less than 5×10-2Pa when heating to above 500℃, during the insulation process, and before filling with argon.

[0043] S4: Solution treatment of thin-walled cavity parts after 3D printing;

[0044] S5: Separate the substrate and the thin-walled cavity part by wire cutting, fix the removed thin-walled cavity part on a vise, and remove the support on the part with a rubber hammer and chisel;

[0045] S6: Perform dimensional inspection and nondestructive inspection on the thin-walled cavity parts; in this embodiment, preferably, in S6, the nondestructive inspection should include penetration inspection and X-ray inspection. When performing penetration inspection, the appearance should be free of cracks and pores; when performing X-ray inspection, the internal quality should be free of cracks, unfused, and dense pores, and the other quality requirements should meet the specified technical conditions and acceptance conditions; dimensional inspection adopts three-dimensional scanning;

[0046] S7: Fix the thin-walled cavity parts with tooling; in this embodiment, preferably, the tooling materials in step S7 are all high-temperature alloys of the same grade, and are also printed through steps S1-S5 and subjected to non-destructive testing in S6 to ensure that the tooling linear expansion coefficient is consistent with that of the thin-walled cavity parts, so as to facilitate welding and stress relief annealing after welding, and the tooling constrains the thin-walled cavity parts; insert the thin-walled cavity parts into the main frame from top to bottom, and turn the top cam lock 2, the middle cam lock 5 and the bottom cam lock 10 in turn, and push the top sector block 1, the middle sector block 8 and the bottom sector block 11 outward respectively, so that the outer side of the sector block conforms to the inner wall of the thin-walled cavity parts, and then lock the corresponding cam lock by positioning and locking the threaded column, so as to realize the reverse deformation of the cavity parts; the part protection gasket 9 added on the platform can prevent the platform and the bolts from directly contacting and extruding to cause damage to the parts; when the welding is completed, the parts are lifted together with the tooling through the lifting ring 13 and put into the heat treatment equipment;

[0047] S8: Most of the through holes of the thin-walled cavity are blocked, leaving only two holes, one hole for introducing argon gas and the other hole for discharging argon gas, so as to form a protective gas circulation;

[0048] S9: Place the thin-walled cavity parts into the tooling for plate sealing welding; in this embodiment, preferably, in step S9, before welding, check whether the surfaces of the parts and welding wires are cleaned, whether all the knobs on the welding machine panel are in the preset position, whether the argon bottle valve is in the open state, and whether the argon gas circulation is unobstructed; seal the through holes of the parts with high-temperature tape, and inflate the inner cavity to protect the back during welding. The argon flow rate before welding is not less than 15L / min, and the argon filling time is not less than 15min. The argon flow rate for back protection during welding is 5L / min-15L / min. The welding process is: welding current 35A-50A, welding speed 3-10mm / s, argon flow rate 10L / min-15L / min; mark the areas to be welded, a total of 16 areas, area 1 is opposite to area 2, area 1 is 90° counterclockwise to area 3, area 3 is opposite to area 4, area 5 is on the left of area 1, and areas 5-16 are marked in the same way. The welding trajectory is pre-pressed Figure 4The gap between the thin-walled cavity part and the groove of the sealing plate is 0.1-0.8mm. Spot welding is used for positioning first. After positioning welding, check that there is no obvious misalignment in the welded joint. The two-person symmetrical back-welding method is used. First, weld the 1-1 weld and the 1-2 weld. Another person welds the 2-1 weld and the 2-2 weld at the same time. The same goes for areas 3-16. After welding the 1 and 2 welds in all areas, weld 1-3 and 1-4. Another person welds 2-3 and 2-4 until areas 3-16 are welded. Polish the front of the weld after welding. It should be noted that before welding, if any of the welding materials, parent materials, welding equipment, welding process, welder, welding environment, or welding structure has changed, or if it is the first welding, a welding process assessment should be carried out using a similar structure, the same material, and the same process. When welding this product, the welding specimen design and room temperature and high temperature performance tests have been performed. The specimen design is as follows: Figure 5 The performance test data is shown in Table 1;

[0049] Table 1 Test results of room temperature and high temperature tensile properties of high temperature alloys

[0050]

[0051]

[0052] S10: After welding, stress relief annealing is performed on the weld position of the thin-walled cavity part;

[0053] In this embodiment, preferably, in S10, when stress relief annealing is performed, the tooling and parts are sent into a vacuum furnace as a whole; the vacuum degree, temperature, holding time, and cooling method process parameters are strictly controlled; under the condition that the vacuum degree P value is less than 10Pa, the temperature is heated from room temperature to 850℃±10℃ at a specific heating rate, and 1000-1500mbar argon is filled in after the holding is completed for rapid cooling, and the furnace temperature drops to room temperature; the vacuum pressure should be less than 5×10 -2 Pa.

[0054] S11: After welding, perform non-destructive testing on the weld and perform dimensional testing on the entire structure.

[0055] In this embodiment, preferably, the nondestructive testing in S11 should include penetration testing and X-ray testing. When performing penetration testing, the appearance should be free of cracks and pores; when performing X-ray testing, the internal quality should be free of cracks, unfused parts, and dense pores, and the other quality requirements should meet the specified technical conditions and acceptance conditions; Dimension detection adopts three-dimensional scanning, and after the scanning, the figure needs to be fitted with the data recorded in step S6 and the deviation is compared. The dimensional deviation is ±0.45mm, which meets the requirements specified in the part drawing.

[0056] Although embodiments of the present invention have been shown and described (see the above detailed description for details), it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A large-scale 3D printed closed cavity thin-walled parts anti-deformation welding tool, characterized by: The tooling comprises, from top to bottom, a top circular ring (14), a middle circular ring (7), and a base (12), and the top circular ring (14), the middle circular ring (7), and the base (12) are connected by a plurality of columns (6) to form a main frame, a circle of bottom sector blocks (11) whose inner diameter can be slidably adjusted are installed on the base (12) by means of fastening bolts (3), and a bottom cam lock (10) for driving the bottom sector blocks (11) to expand is rotatably installed on the base (12) by means of cam lock studs (4), and a circle of bottom sector blocks (11) whose inner diameter can be slidably adjusted is installed on the middle circular ring (7) by means of fastening bolts (3). The middle-layer sector block (8) is rotatably mounted on the middle-layer circular ring (7) via a cam lock stud (4) for driving the middle-layer sector block (8) to expand; a circle of top-layer sector blocks (1) with an inner diameter that can be slidably adjusted is mounted on the top-layer circular ring (14) via a fastening bolt (3); a top-layer cam lock (2) is rotatably mounted on the top-layer circular ring (14) via a cam lock stud (4) for driving the top-layer sector block (1) to expand; the top-layer cam lock (2), the middle-layer cam lock (5) and the bottom-layer cam lock (10) are all provided with positioning locking threaded columns for limiting their own rotation.

2. According to claim 1, a large-scale 3D printed closed cavity thin-walled part anti-deformation welding tool is characterized by: A pair of lifting rings (13) are symmetrically arranged on the top of the base (12), and the lifting rings (13) are connected to the base (12) by screw thread; the bottom of a circle of the middle sector blocks (8) are connected to the parts protection gasket (9) by screw rods, and the top sector blocks (1), the middle sector blocks (8) and the bottom sector blocks (11) are all provided with strip guide grooves that match the corresponding fastening bolts (3).

3. A large-scale 3D printed closed cavity thin-walled part anti-deformation welding method, characterized in that: The tooling as claimed in claim 1-2 is used, and the specific method includes: S1: adding support to the thin-walled cavity part model, supplementing the blank margin, and closing the cavity structure to open a window for removing the support; S2: Raw material preparation, using metal alloy powder with a powder particle size of 15-53μm; S3: Start the equipment to perform 3D printing of thin-walled cavity parts; S4: heat treatment of the thin-walled cavity parts after 3D printing; S5: Separate the substrate and the thin-walled cavity part by wire cutting, fix the removed thin-walled cavity part on a vise, and remove the support on the part with a rubber hammer and chisel; S6: Dimensional inspection and non-destructive testing of thin-walled cavity parts; S7: Fixing the thin-walled cavity component using the tooling; S8: Most of the through holes of the thin-walled cavity are blocked, leaving only two holes, one hole for introducing argon gas and the other hole for discharging argon gas, so as to form a protective gas circulation; S9: Place the thin-walled cavity parts into the tooling for sealing plate welding; S10: After welding, stress relief annealing is performed on the weld position of the thin-walled cavity part; S11: After welding, perform non-destructive testing on the weld and perform dimensional testing on the entire structure.

4. A large-scale 3D printed closed cavity thin-walled part anti-deformation welding method according to claim 3, characterized in that: In S1, in order to ensure that the upper wall does not collapse during the printing process, 16 evenly distributed strip windows need to be opened for a whole circle of the cavity structure during model processing, and it is convenient to remove the support; in S2, when preparing the raw materials, it is necessary to check and record the brand, quantity, specification, and batch number information of the metal alloy powder. After checking, use a shovel to add a sufficient amount of metal powder into the equipment material compartment. The diameter of the cavity thin-wall part is greater than 1000mm.

5. A large-scale 3D printed closed cavity thin-walled part anti-deformation welding method according to claim 3, characterized in that: In S3, argon gas is turned on, the air intake pressure is set to 0.5MPa, ventilation circulation, water cooling, scanning galvanometer, and laser are turned on, and when the oxygen content reaches below 1000ppm, the equipment automatically starts the printing process; after the forming is completed, the equipment automatically stops printing, and the part can be taken out when the substrate temperature drops below 40°C; during the whole process of taking out the parts, the explosion-proof vacuum cleaner is turned on to absorb the floating dust in the forming chamber in time; During the printing process, the cover plates corresponding to the 16 windows need to be printed together with the furnace; During the printing process, test bars and test plates for mechanical properties testing should be prepared with the furnace; in S4, when heat treatment is performed, the temperature is heated from room temperature to 260°C-950°C at a specific heating rate under the condition that the vacuum P value is less than 10Pa, and the temperature is kept for 1-4h. After the heat treatment, 1000-1500mbar argon gas is filled for rapid cooling, and the furnace temperature drops to room temperature; the vacuum pressure during heating to above 250°C, during the insulation process, and before the argon gas is filled should be less than 5×10 -2 Pa.

6. A large-scale 3D printed closed cavity thin-walled part anti-deformation welding method according to claim 3, characterized in that: In S6, non-destructive testing should include penetration testing and X-ray testing. When conducting penetration testing, the appearance should be free of cracks and pores; when conducting X-ray testing, the internal quality should be free of cracks, unfused parts, and dense pores. The remaining quality requirements must comply with the specified technical conditions and acceptance conditions; dimensional detection adopts three-dimensional scanning.

7. A large-scale 3D printed closed cavity thin-walled part anti-deformation welding method according to claim 3, characterized in that: The tooling materials in step S7 are all high-temperature alloys of the same grade, and are also printed through steps S1-S5 and subjected to non-destructive testing in S6 to ensure that the linear expansion coefficient of the tooling is consistent with that of the thin-walled cavity part, so as to facilitate welding and stress relief annealing after welding, and the tooling can restrain the thin-walled cavity part; the thin-walled cavity part is inserted into the main frame from top to bottom, and the top cam lock (2), the middle cam lock (5) and the bottom cam lock (10) are rotated in sequence to push the top sector block (1), the middle sector block (8) and the bottom sector block (11) outward respectively, so that the outer side of the sector block conforms to the inner wall of the thin-walled cavity part, and then the corresponding cam lock is locked by the positioning locking threaded column to achieve the reverse deformation of the cavity part; the part protection gasket (9) added to the platform can prevent the platform and the bolt from directly contacting each other to generate extrusion and cause damage to the part; when the welding is completed, the part is lifted together with the tooling through the lifting ring (13) and put into the heat treatment equipment.

8. A large-scale 3D printed closed cavity thin-walled part anti-deformation welding method according to claim 3, characterized in that: In the S9, before welding, check whether the surface of the parts and welding wire are clean, whether all the knobs on the welding machine panel are in the preset position, whether the argon bottle valve is in the open state, and whether the argon gas circulation is unobstructed; seal the through holes of the parts with high-temperature tape, and inflate the inner cavity to protect the back during welding. The argon gas flow rate before welding is not less than 15L / min, and the argon filling time is not less than 15min. The back gas protection argon gas flow rate during welding is 5L / min-15L / min. The welding process is: welding current 35A-50A, welding speed 3-10mm / s, argon gas flow rate 10L / min-15L / min; mark the areas to be welded, a total of 16 areas, area 1 is opposite to area 2, area 1 is 90° counterclockwise to area 3, area 3 is opposite to area 4, area 5 is on the left side of area 1, and areas 5-16 are marked in sequence in the same way. Spot welding is first performed for positioning. After positioning welding, check that the welded joint has no obvious misalignment; a two-person symmetrical back welding method is used.

9. A large-scale 3D printed closed cavity thin-walled part anti-deformation welding method according to claim 3, characterized in that: When performing stress relief annealing in S10, the tooling and parts are put into a vacuum furnace as a whole; under the condition that the vacuum degree P value is less than 10Pa, the furnace is heated from room temperature to 200°C-850°C at a specific heating rate, and after the temperature is kept for 1-4 hours, 1000-1500mbar argon is filled for rapid cooling, and the furnace temperature drops to room temperature; the vacuum pressure should be less than 5×10 -2 Pa.

10. A large-scale 3D printed closed cavity thin-walled part anti-deformation welding method according to claim 3, characterized in that: The nondestructive testing in step S11 should include penetration testing and X-ray testing. When performing penetration testing, the appearance should be free of cracks and pores; when performing X-ray testing, the internal quality should be free of cracks, unfused, and dense pores; Dimension detection adopts three-dimensional scanning. After the scanning, the figure needs to be fitted with the data recorded in step S6 and the deviation is compared. The dimensional deviation should meet the requirements specified in the part drawing of ±1.0mm.

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