Aero-engine hollow blade and brazing method thereof

Abstract

The invention relates to the technical field of welding, in particular to an aero-engine hollow blade and a brazing method thereof. During welding, all parts of the hollow blade are clamped and fixed so as to guarantee the matching precision of the parts, meanwhile, brazing filler metal pieces are placed at the to-be-welded positions of the cover plate and the blade body, paste brazing filler metal is added to welding gaps, welding is conducted through the two kinds of brazing filler metal, the welding quality is guaranteed, impurities and oxides on the surfaces of the parts are removed before welding, and the welding quality is improved. The flowing effect of the paste brazing filler metal is guaranteed, a hydrogen atmosphere brazing process is combined, oxidation reduction can be carried out on parts during welding, the oxidation defect of the parts is avoided, the flowing effect of the paste brazing filler metal is further improved, welding gaps can be completely filled with the brazing filler metal during welding, the conditions of pseudo soldering or air holes and the like are avoided, and the condition of weld joint leakage is avoided. And the welding quality is further improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of welding, more particularly to an aero-engine hollow blade and a brazing method thereof. BACKGROUND

[0002] The aero-engine hollow blade is a high-strength and high-precision part, and its processing mode is generally one of integral processing and welding processing according to different types of blades. For the hollow blade processed by welding, the processing precision is high, and the processing difficulty is also high. For a type of aero-engine hollow blade, the whole blade includes a blade body, a cover plate and a shaft neck, and is composed of two typical brazing types: one is the brazing of the shaft neck and the blade body with different materials (the materials of the blade body and the cover plate: QBe0.6-2.5, and the material of the shaft neck: 0Cr15Ni5Cu2Ti); and the other is the brazing of the blade body and the cover plate with the same material. According to the shapes of the welding positions, the hollow blade brazing joint forms include three types of welding seams, i.e., pipe-pipe lap joint, plate-plate lap joint and plate-plate lock bottom joint. Therefore, the part belongs to a precision and complex structure part with multiple welding joint forms and multiple welding seam types, and it is difficult to pass the brazing once.

[0003] In the prior art, some technicians use argon atmosphere brazing to process the part, but the welding seam quality of the part is required to be high. After the argon atmosphere brazing, the welding position is seriously virtual welded or has serious gas hole, which causes the cover plate to have serious welding seam leakage, and the processing difficulty is great. In addition, due to the three-dimensional curved surface and special structure of the blade type surface of the part, it is difficult to ensure the consistency of the brazing gap during the argon atmosphere brazing, and local brazing seam penetration inspection is not qualified, so that the virtual welding and gas hole position needs to be repaired, and multiple repair welding is not qualified, which causes the part to be scrapped. SUMMARY

[0004] In order to overcome the defects that the welding technology in the prior art cannot meet the welding requirements of the aero-engine hollow blade, the present application provides a brazing method of the aero-engine hollow blade, which improves the welding quality and meets the welding requirements.

[0005] To solve the above technical problems, the technical scheme adopted by the present application is as follows: a brazing method of an aero-engine hollow blade, comprising the following steps: Step 1: cleaning the blade body, the cover plate and the shaft neck to remove impurities and oxides on the surfaces of the parts; Step 2: cutting the brazing sheet to be just embedded in the shaft neck, combining the tenon of the shaft neck and the blade body, and spreading the brazing sheet on the blade body and the shaft neck to be welded; Step 3: brushing the flow resistance agent around the blade body to be welded to protect the air duct of the hollow blade and prevent the brazing material from flowing and causing the air duct to be blocked; Step four: according to the shape of the blade to be welded, punch the filler metal sheet, after brushing the brazing flux water on the surface of the blade to be welded, paste the filler metal sheet on the welding position, then press the cover plate on the filler metal sheet, make the cover plate embedded in the blade cavity, and leave a welding gap between the cover plate and the blade, then use the pre-clamping fixture to pre-clamp the cover plate to ensure that the filler metal sheet and the cover plate are not dislocated; Step five: add paste filler metal at the welding gap between the cover plate and the blade, and brush the flow-resistant agent around the position where the paste filler metal is added to prevent the filler metal from flowing to other positions of the blade; Step six: remove the pre-clamping fixture, use the brazing fixture to clamp each welding position to achieve the required gap between the blade and the cover plate, during the process, set a separator between the cover plate and the brazing fixture, make the separator adhere to the brazing fixture and the part, and separate the brazing fixture from the part to avoid the filler metal welding the brazing fixture and the part together; Step seven: use hydrogen atmosphere brazing process for welding, after the hydrogen gas is purified, put the assembled product into the hydrogen atmosphere brazing furnace, vacuumize the hydrogen atmosphere brazing furnace to ≤10 -2 Pa, fill the protective gas to drive away the air in the furnace, then introduce hydrogen, ignite the hydrogen at the ignition point of the hydrogen atmosphere brazing furnace, and follow the hydrogen atmosphere brazing heat cycle curve to perform heating, holding and cooling; Step eight: after the hydrogen atmosphere brazing furnace, check the appearance of the hollow blade weld; Step nine: perform solid solution and aging treatment according to the corresponding materials of each part; Step ten: perform final inspection on the product, and complete the production after the inspection is qualified.

[0006] Specifically, after brushing the flow-resistant agent, the subsequent operation needs to be performed after the flow-resistant agent is dried, the brushing of the flow-resistant agent can be performed in advance according to the situation to save time. The separator is made of high-temperature resistant material. The pre-clamping fixture realizes the preliminary fixation of the blade and the cover plate, and also ensures that the distance of the welding gap remains unchanged. After fixation, the paste filler metal and the flow-resistant agent are added and dried to the required state of the process, then the pre-clamping fixture is removed and replaced with the brazing fixture. To avoid deformation of the brazing fixture, the brazing fixture is made of nickel-based high-temperature alloy, or other materials that can maintain no deformation at 960℃ or above for 20 minutes. Further, the clamping force of the brazing fixture is 21 Newton-meters ± 1 Newton-meters, which can effectively ensure the brazing gap and the non-deformation of the hollow blade.

[0007] In addition, in step one, acetone is used to clean the cover plate, blade body and shaft neck to remove oil stains and other impurities. In step two, the welding surfaces of the blade body and the cover plate are polished to further clean and remove oxides, and then the filler metal sheet is cut and the shaft neck is assembled, and the filler metal sheet should not be damaged during the process. Specifically, the welding surface of the cover plate is polished by a polishing head with a hundred abrasive cloth to ensure that the welding surface of the cover plate does not produce chamfering; the welding surface of the blade body is polished by a diamond polishing head to effectively remove the oxidation at the root of the step. The internal cavity is not allowed to appear in the welding surface. In step three, the flow resistance agent is brushed on the position which is more than 1mm outside the welding surface of the blade body. In step five, the flow resistance agent is brushed on the position which is more than 1mm outside the position where the paste filler is added, that is, the distance between the position where the flow resistance agent is brushed and the welding surface or the position where the paste filler is added is at least 1mm. In step seven, the protective gas includes argon and nitrogen. In step eight, the inspection method of the appearance of the weld includes kerosene penetration inspection, X-ray inspection and ultrasonic inspection, etc.

[0008] By the above brazing method, the parts of the hollow blade are clamped and fixed during welding to ensure the fitting accuracy of the parts, and the filler metal sheet is placed at the welding surface of the cover plate and the blade body, and the paste filler is added at the welding gap, two kinds of filler metals are used for welding to ensure the welding quality, and the impurities and oxides on the surface of the parts are removed before welding to ensure the flow effect of the paste filler, and then the hydrogen atmosphere brazing process is combined, the parts can be oxidized and reduced during welding to avoid oxidation defects of the parts, further improve the flow effect of the paste filler, so that the filler metal can completely fill the welding gap during welding, avoid virtual welding or porosity, avoid weld leakage, and further improve the welding quality.

[0009] Preferably, in step one, the liquid sandblasting process is used to preliminarily remove the impurities and oxide layer on the surface of the parts, and then the parts are dried, and then the parts are loaded into the hydrogen atmosphere brazing furnace for baking reduction, the welding surface of the parts is placed upward to make it fully contact with hydrogen, then vacuum is extracted, argon is filled, vacuum is extracted, hydrogen is filled, and then the purity of hydrogen at the outlet of the hydrogen atmosphere brazing furnace is verified. After reaching the standard, the hydrogen atmosphere brazing furnace is heated to a baking temperature of 500℃±50℃, the holding time is 30-40min, and then the furnace is cooled down, and then the parts are taken out of the furnace for standby.

[0010] The high-temperature baking is used to oxidize and reduce the surface of the parts to fully remove the oxides and improve the welding quality.

[0011] Preferably, in steps two and four, the thickness of the filler metal sheet is selected in the range of 0.1-0.3mm.

[0012] The thickness of the filler metal sheet is selected according to the assembly gap of the parts, or the assembly gap of the parts is determined according to the thickness of the filler metal sheet.

[0013] Preferably, in step three, among the air passages arranged on the blade, at least the air passages at both ends are provided with blocking elements to block the air passages, so as to prevent the brazing filler metal from clogging the air passages.

[0014] Specifically, the blocking components should be placed in the air passages at both ends of the journal axis. The air passages at both ends are close to the edge of the cover plate, so the solder paste from the edge of the cover plate can easily flow into the air passages during welding. At the same time, the blocking components can also be placed in the openings of all air passages to fully avoid air passage blockage.

[0015] Preferably, in steps three and six, both the blocking element and the separator are made of ceramic fiber paper.

[0016] For the use of blocking components, ceramic fiber paper is directly stuffed into the air passage opening of the hollow blade to prevent the brazing filler metal from flowing into the air passage; for the use of separating components, ceramic fiber paper is covered on the cover plate to separate the cover plate from the brazing fixture, and also to protect the cover plate and prevent it from being scratched.

[0017] Preferably, in step six, a flow-blocking agent is first applied to the brazing fixture, and then the part is clamped. The brazing fixture includes an upper part, a lower part, and a clamping component. The surface of each part is designed and manufactured according to the surface of the part. After the upper part and the lower part are combined, they are clamped and fixed by the clamping component so that the blade and the cover plate reach the gap required for brazing and ensure the brazing quality. The separator is set between the cover plate and the upper part.

[0018] A flow-blocking agent is brushed onto the brazing fixture to further prevent parts from being welded together with the brazing fixture.

[0019] Preferably, the brazing fixture only clamps each surface of the part to be welded, and the distance between the edge of the clamping position and the edge of the cover plate contour is 0.1-0.5mm.

[0020] Preferably, in step seven, during welding, the temperature in the hydrogen atmosphere brazing furnace is raised from room temperature to 600°C in 80-90 minutes, held for 60-65 minutes, raised to 760°C in 18-25 minutes, held for 45-55 minutes, raised to 960°C in 22-28 minutes, held for 18-22 minutes, and then cooled to 400°C with the furnace before being rapidly cooled by a blower. The furnace is then removed from the furnace at a temperature below 70°C.

[0021] Preferably, in step one, a welding bevel is provided on the blade and / or cover plate so that the solder paste can fill the weld gap during welding.

[0022] Setting a welding bevel further improves the flow properties of the brazing filler metal, avoids incomplete welds and porosity, and ensures that the brazing filler metal can completely fill the weld gap during welding.

[0023] A hollow blade for an aero-engine includes a blade body, a journal and a cover plate respectively connected to the blade body. The journal and the cover plate are welded to the blade body by the aforementioned brazing method. The blade body and / or the cover plate are provided with a welding bevel. Further, the welding bevel is chamfered and the inclination angle is 30°-60°.

[0024] Compared with the prior art, the beneficial effects of the present invention are: The above brazing method clamps and fixes each part of the hollow blade during welding to ensure the precision of the parts' fit. Simultaneously, brazing filler metal sheets are placed at the welding points on the cover plate and blade body, and brazing paste is added to the welding gaps. Using two types of brazing filler metal ensures welding quality. Before welding, impurities and oxides on the surface of the parts are removed to ensure the flowability of the brazing paste. Combined with hydrogen atmosphere brazing, the parts undergo oxidation-reduction during welding, preventing oxidation defects and further enhancing the flowability of the brazing paste. This allows the brazing filler metal to completely fill the welding gaps, preventing incomplete welds or porosity, and avoiding weld leakage, thus further improving welding quality. Attached Figure Description

[0025] Figure 1 This is a flowchart of a brazing method for hollow blades of an aero-engine according to the present invention; Figure 2 This is a schematic diagram of the overall structure of a hollow blade for an aero-engine according to the present invention; Figure 3 This is a schematic diagram of the conventional structure of the cover plate for existing hollow blades of aero engines; Figure 4 This is a schematic diagram of the structure of a cover plate for a hollow blade of an aero-engine according to the present invention; Figure 5 This is a schematic diagram of the arrangement of the flow throttling agent and the blocking component in a brazing method for hollow blades of an aero-engine according to the present invention. Figure 6 This is a schematic diagram of a welding defect in a hollow blade of an aero-engine according to the present invention; Figure 7 This is a schematic diagram of the welding porosity of a hollow blade for an aero-engine according to the present invention; Figure 8 This is a welding schematic diagram of a brazing method for hollow blades of an aero-engine according to the present invention.

[0026] In the diagram: 1. Blade; 2. Cover plate; 3. Journal; 4. Welding bevel; 5. Air passage; 6. Brazing filler metal sheet; 7. Brazing paste; 8. Flow retardant; 9. Blocking component. Detailed Implementation

[0027] The accompanying drawings are for illustrative purposes only and should not be construed as limiting this patent. To better illustrate this embodiment, some components in the drawings may be omitted, enlarged, or reduced, and do not represent the actual dimensions of the product. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings. The positional relationships described in the drawings are for illustrative purposes only and should not be construed as limiting this patent.

[0028] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "long," and "short" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present patent. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0029] The technical solution of the present invention will be further described in detail below through specific embodiments and in conjunction with the accompanying drawings: Example 1 like Figure 1 As shown, a brazing method for hollow blades of an aero-engine includes the following steps: Step 1: Clean the blade 1, cover plate 2 and journal 3 to remove impurities and oxides from the surface of each part; Step 2: Cut the brazing filler piece 6 to fit perfectly inside the journal 3, and combine the journal 3 with the tenon of the blade body 1 so that the brazing filler piece 6 is properly laid out on the surfaces of the blade body 1 and the journal 3 to be welded. Step 3: Apply flow-blocking agent 8 around the surface of the blade 1 to be welded to protect the air passage 5 of the hollow blade and prevent the brazing filler metal from overflowing and causing blockage of the air passage 5. Step 4: According to the shape of the area to be welded on the blade 1, cut the brazing filler sheet 6. After brushing the brazing flux on the surface of the blade 1 to be welded, attach the brazing filler sheet 6 to the area to be welded, and then press the cover plate 2 on the brazing filler sheet 6 so that the cover plate 2 is embedded into the cavity of the blade 1, leaving a welding gap between the cover plate 2 and the blade 1. Then use a pre-clamping fixture to pre-clamp the cover plate 2 to ensure that the brazing filler sheet 6 and the cover plate 2 are not misaligned. Step 5: Fill the weld seam between the cover plate 2 and the blade 1 with solder paste 7, and brush the surrounding area of ​​the solder paste 7 with a flow-blocking agent 8 to prevent the solder from flowing to other parts of the blade 1. Step 6: Remove the pre-clamping fixture and use the brazing fixture to clamp the welding parts so that the blade 1 and the cover plate 2 reach the required gap for brazing. During the process, a separator is set between the cover plate 2 and the brazing fixture to make the separator fit with the brazing fixture and the parts, and to separate the brazing fixture from the parts, so as to prevent the brazing filler metal from welding the brazing fixture and the parts together. Step 7: Welding is carried out using hydrogen atmosphere brazing process. After the hydrogen gas is tested and found to be pure, the assembled product is placed in the hydrogen atmosphere brazing furnace. The hydrogen atmosphere brazing furnace is evacuated to ≤10-2 Pa, and protective gas is introduced to drive out the air in the furnace. Then hydrogen gas is introduced and ignited at the ignition point of the hydrogen atmosphere brazing furnace. Heating, holding and cooling are carried out according to the hydrogen atmosphere brazing thermal cycle curve. Step 8: After the hollow blades are brazed in a hydrogen atmosphere, inspect the appearance of the weld seam. Step 9: Perform solution treatment and aging according to the corresponding materials of each part; Step 10: Conduct a final inspection of the product. Production is completed after the product passes the inspection.

[0030] Specifically, in the above method, after applying the flow-restricting agent 8, it is necessary to wait for the flow-restricting agent 8 to dry before proceeding with subsequent operations. The flow-restricting agent 8 can be applied earlier as needed to save time. The separator is made of high-temperature resistant material. The pre-clamping fixture achieves initial fixation of the blade 1 and the cover plate 2, and also ensures that the spacing of the weld gap remains unchanged. After fixation, brazing paste 7 is added and flow-restricting agent 8 is applied. After the brazing paste 7 and flow-restricting agent 8 dry to the required state, the pre-clamping fixture is removed and replaced with a brazing fixture. To avoid deformation of the brazing fixture, it is made of a nickel-based high-temperature alloy, or other materials that can remain undeformed at temperatures above 960℃ for 20 minutes. Furthermore, the clamping force of the brazing fixture is 21 Nm ± 1 Nm, which effectively ensures the brazing gap and prevents deformation of the hollow blade.

[0031] In addition, in step one, acetone is used to clean and remove oil and other impurities from the cover plate 2, blade 1, and journal 3. In step two, the surfaces to be welded on the blade 1 and cover plate 2 are first polished to further clean and remove oxides. Then, the brazing filler metal sheet 6 is cut and the journal 3 is assembled, taking care to avoid damaging the brazing filler metal sheet 6 during the process. Specifically, the area to be welded on the cover plate 2 is polished with a scouring pad to ensure that no chamfer is formed. The area to be welded on the blade 1 is polished with a diamond grinding head to effectively remove oxidation at the root of the step. No internal cavities are allowed at the area to be welded. In step three, flow-blocking agent 8 is brushed on at least 1 mm beyond the surface to be welded on the blade 1. In step five, flow-blocking agent 8 is brushed on at least 1 mm beyond the location where the brazing paste 7 is added, meaning the brushed area of ​​flow-blocking agent 8 is at least 1 mm away from the surface to be welded or the brazing paste 7. In step seven, the protective gases include argon and nitrogen. In step eight, the methods for inspecting the appearance of the weld include kerosene penetration testing, X-ray inspection, and ultrasonic testing.

[0032] The beneficial effects of this embodiment are as follows: During welding, the hollow blade components are clamped and fixed to ensure the precision of the component fit. At the same time, brazing filler metal sheets 6 are placed at the welding points on the cover plate 2 and the blade body 1, and brazing paste 7 is added to the welding gap. The use of two types of brazing filler metal ensures the welding quality. Before welding, impurities and oxides on the surface of the components are removed to ensure the flow effect of the brazing paste 7. Combined with the hydrogen atmosphere brazing process, the components can be oxidized and reduced during welding to avoid oxidation defects. This further improves the flow effect of the brazing paste 7, allowing the brazing filler metal to completely fill the welding gap during welding, avoiding incomplete welding or porosity, and preventing weld leakage, thus further improving the welding quality.

[0033] Example 2 This embodiment further defines the features of Embodiment 1, and its difference from Embodiment 1 lies in: In step one, a liquid sandblasting process is used to initially remove impurities and oxide layers from the surface of the parts. The parts are then dried and placed in a hydrogen atmosphere brazing furnace for reduction and heating. The parts are placed with the welding side facing upwards to ensure full contact with hydrogen. The process involves sequentially vacuuming, argon filling, vacuuming again, and hydrogen filling. The purity of the hydrogen at the furnace outlet is then verified. Once the purity is met, the furnace is heated to a heating temperature of 500℃±50℃ and held for 30-40 minutes. The furnace is then cooled, and the parts are removed for later use. High-temperature heating effectively reduces oxidation on the part surface, thoroughly removing oxides and improving welding quality.

[0034] Furthermore, in steps two and four, the thickness of the solder sheet 6 is selected within the range of 0.1-0.3mm. Specifically, the thickness of the solder sheet 6 is selected based on the assembly clearance of the parts, or the machining assembly clearance of the parts is determined based on the thickness of the solder sheet 6.

[0035] Furthermore, in step three, at least the air passages 5 arranged on the blade body 1 are blocked by blocking elements 9 at both ends to prevent the solder from clogging the air passages 5. Specifically, the blocking elements 9 are preferably placed in the air passages 5 located at both ends along the axis of the journal 3. The air passages 5 located at both ends are close to the edge of the cover plate 2, so that the solder paste 7 at the edge of the cover plate 2 can easily flow into the air passages 5 during welding. At the same time, the blocking elements 9 can also be placed in the openings of all air passages 5 to fully avoid clogging of the air passages 5.

[0036] Furthermore, in steps three and six, both the blocking component 9 and the separator are made of ceramic fiber paper. For the blocking component 9, the ceramic fiber paper is directly inserted into the opening of the air passage 5 of the hollow blade to prevent the brazing filler metal from flowing into the air passage 5. For the separator, the ceramic fiber paper is covered on the cover plate 2 to separate the cover plate 2 from the brazing fixture, and also to protect the cover plate 2 from scratches.

[0037] Furthermore, in step six, flow-restricting agent 8 is first applied to the brazing fixture before the parts are clamped. The brazing fixture includes an upper part, a lower part, and clamping components, and all surfaces are designed and manufactured according to the part's profile. After the upper and lower parts are combined, they are clamped and fixed using the clamping components to ensure that the blade 1 and the cover plate 2 achieve the required gap for brazing, thus guaranteeing brazing quality. A separator is placed between the cover plate 2 and the upper part. Applying flow-restricting agent 8 to the brazing fixture further prevents the parts from being welded together with the brazing fixture.

[0038] Furthermore, the brazing fixture only clamps the surfaces of the parts to be welded, and the distance between the edge of the clamping position and the edge of the cover plate 2 contour is 0.1-0.5mm.

[0039] Furthermore, in step seven, during welding, the temperature in the hydrogen atmosphere brazing furnace is raised from room temperature to 600℃ in 80-90 minutes, held for 60-65 minutes, raised to 760℃ in 18-25 minutes, held for 45-55 minutes, raised to 960℃ in 22-28 minutes, held for 18-22 minutes, and then cooled to 400℃ in the furnace before being rapidly cooled by the blower. The furnace is then removed from the furnace at a temperature below 70℃.

[0040] Furthermore, in step one, a welding bevel 4 is provided on the blade 1 and / or cover plate 2, allowing the solder paste 7 to fill the weld gap during welding. Providing the welding bevel 4 further improves the flowability of the solder, preventing incomplete welds and porosity, and ensuring that the solder completely fills the weld gap during welding.

[0041] Specifically, the groove at the welding point of blade 1 is 1 mm deep. The blade 1 profile is inserted, and the distance between the cover plate 2 and blade 1 (i.e., the welding gap) is 0.1 mm. Existing blade structures are as follows: Figure 3 As shown, an internal cavity exists at the overlap between the cover plate 2 and the blade 1. This prevents the solder paste 7 applied to the outside from completely filling the cavity, resulting in internal defects in the weld of the hollow blade. After the excess material is removed during machining, the cavity defect is exposed, causing appearance quality issues. Furthermore, the presence of the internal cavity reduces the overlap area between the cover plate 2 and the blade 1, thus increasing the risk of weld defects such as leakage and a reduced weld bearing area. Figure 3 Structures often appear in actual production.

[0042] like Figure 4As shown, the optimized structure is the most advantageous for filling the gaps with brazing filler metal during hydrogen atmosphere brazing of hollow beryllium cobalt copper blades. The cavity structure at the overlap between the cover plate 2 and the blade body 1 has been removed, and a welding bevel 4 has been provided on the cover plate 2. The advantages are: it facilitates the operator in adding the paste brazing filler metal 7; the paste brazing filler metal 7 will not be squeezed off the weld by the upper part of the brazing fixture, avoiding the quality problem of missing brazing filler metal in the weld; the brazing filler metal is added closer to the step overlap surface between the cover plate 2 and the blade body 1, which is conducive to the flow of brazing filler metal and thus completely fills the weld gap, preventing leakage and non-compliance caused by weld defects.

[0043] like Figure 6 and Figure 7 As shown, in conventional methods, incomplete soldering and porosity occur at the brazed joints, such as... Figure 8 As shown, after welding using this brazing method, there are no cases of incomplete welds or porosity in the welded area, and the welding quality meets production requirements.

[0044] The remaining features and working principles of this embodiment are the same as those of Embodiment 1.

[0045] Example 3 like Figure 2 and Figure 5 As shown, a hollow blade for an aero-engine includes a blade body 1, a journal 3 and a cover plate 2 respectively connected to the blade body 1. The journal 3 and the cover plate 2 are welded to the blade body 1 by the brazing method of Embodiment 1 or Embodiment 2. The blade body 1 and / or the cover plate 2 are provided with a welding bevel 4. Further, the welding bevel 4 is chamfered and the inclination angle is 30°-60°.

[0046] The brazing method in Example 1 or 2 is applicable to the welding of this hollow blade. The hollow blade is provided with a welding bevel 4 to further improve the flow performance of the brazing filler metal, avoid incomplete welds and porosity, and ensure that the brazing filler metal can completely fill the weld gap during welding. The blade body 1 is also provided with an air passage 5, and the opening of the air passage 5 is blocked with ceramic fiber paper during welding.

[0047] In the specific implementation of the above embodiments, the technical features can be combined in any non-contradictory way. For the sake of brevity, not all possible combinations of the above technical features are described. However, as long as the combination of these technical features is not contradictory, it should be considered to be within the scope of this specification.

[0048] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A brazing method for hollow blades of an aero-engine, characterized in that, Includes the following steps: Step 1: Clean the blade, cover plate and journal to remove impurities and oxides from the surface of each part; Step 2: Cut the brazing filler metal sheet to fit perfectly into the journal, and assemble the tenon of the journal and the blade body, so that the brazing filler metal sheet is properly spread on the surfaces of the blade body and the journal to be welded. Step 3: Apply a flow-blocking agent around the surface of the blade to be welded to protect the air passages of the hollow blade and prevent the brazing filler metal from overflowing and causing blockage of the air passages; Step 4: According to the shape of the blade to be welded, cut the brazing filler metal sheet. After brushing the brazing flux onto the surface of the blade to be welded, attach the brazing filler metal sheet to the area to be welded, and then press the cover plate onto the brazing filler metal sheet so that the cover plate is embedded into the blade cavity, leaving a welding gap between the cover plate and the blade. Then use a pre-clamping fixture to pre-clamp the cover plate to ensure that the brazing filler metal sheet and the cover plate are not misaligned. Step 5: Fill the weld seam between the cover plate and the blade with solder paste, and brush a flow-blocking agent around the area where the solder paste was applied to prevent the solder from flowing to other parts of the blade. Step 6: Remove the pre-clamping fixture and use the brazing fixture to clamp the welding parts so that the blade and cover plate reach the required gap for brazing. During the process, a separator is placed between the cover plate and the brazing fixture to make the separator fit with the brazing fixture and the part, and to separate the brazing fixture from the part, so as to prevent the brazing filler metal from welding the brazing fixture and the part together. Step 7: Welding is performed using a hydrogen atmosphere brazing process. After the hydrogen purity test is passed, the assembled product is placed in a hydrogen atmosphere brazing furnace, and the furnace is evacuated to a vacuum level of ≤10. -2 Pa, a protective gas is introduced to purge the air in the furnace, and then hydrogen is introduced. The hydrogen is ignited at the ignition point of the hydrogen atmosphere brazing furnace, and the heating, holding and cooling are carried out according to the hydrogen atmosphere brazing thermal cycle curve. Step 8: After the hollow blades are brazed in a hydrogen atmosphere, inspect the appearance of the weld seam. Step 9: Perform solution treatment and aging according to the corresponding materials of each part; Step 10: Conduct a final inspection of the product. Production is completed after the product passes the inspection.

2. The brazing method for a hollow blade of an aero-engine according to claim 1, characterized in that: In step one, liquid sandblasting is used to initially remove impurities and oxide layers from the surface of the parts. The parts are then dried and placed in a hydrogen atmosphere brazing furnace for reduction. The parts are placed with the welding side facing upwards to ensure full contact with hydrogen. The process involves vacuuming, argon filling, vacuuming again, and hydrogen filling in sequence. The purity of the hydrogen at the outlet of the hydrogen atmosphere brazing furnace is then verified. Once the purity is met, the hydrogen atmosphere brazing furnace is heated to a baking temperature of 500℃±50℃ and held for 30-40 minutes. The parts are then cooled with the furnace and removed from the furnace for later use.

3. The brazing method for a hollow blade of an aero-engine according to claim 1, characterized in that: In steps two and four, the thickness of the brazing filler metal sheet can be selected within the range of 0.1-0.3 mm.

4. The brazing method for a hollow blade of an aero-engine according to claim 3, characterized in that: In step three, at least the air passages at both ends of the blade are blocked by a blocking device to prevent the brazing filler metal from clogging the air passages.

5. The brazing method for a hollow blade of an aero-engine according to claim 3, characterized in that: In steps three and six, both the blocking components and the separators are made of ceramic fiber paper.

6. The brazing method for a hollow blade of an aero-engine according to claim 1, characterized in that: In step six, a flow-blocking agent is first applied to the brazing fixture, and then the parts are clamped. The brazing fixture includes an upper part, a lower part, and clamping components. All surfaces are designed and manufactured according to the surface of the parts. After the upper and lower parts are combined, they are clamped and fixed using the clamping components to ensure that the blade and the cover plate reach the required gap for brazing and to ensure the quality of brazing. The separator is set between the cover plate and the upper part.

7. The brazing method for a hollow blade of an aero-engine according to claim 6, characterized in that: The brazing fixture only clamps the surfaces of the parts to be welded, and the distance between the edge of the clamping position and the edge of the cover plate contour is 0.1-0.5mm.

8. The brazing method for a hollow blade of an aero-engine according to claim 1, characterized in that: In step seven, during welding, the temperature in the hydrogen atmosphere brazing furnace is raised from room temperature to 600℃ in 80-90 minutes, held for 60-65 minutes, raised to 760℃ in 18-25 minutes, held for 45-55 minutes, raised to 960℃ in 22-28 minutes, held for 18-22 minutes, and then cooled to 400℃ in the furnace before being rapidly cooled by the blower. The furnace is then removed from the furnace at a temperature below 70℃.

9. The brazing method for a hollow blade of an aero-engine according to claim 1, characterized in that: In step one, a welding bevel is provided on the blade and / or cover plate so that the solder paste can fill the weld gap during welding.

10. A hollow blade for an aero-engine, comprising a blade body (1), a journal (3) and a cover plate (2) respectively connected to the blade body (1), characterized in that, The journal (3) and the cover plate (2) are welded to the blade (1) by any of the brazing methods described in claims 1-9, and the blade (1) and / or the cover plate (2) are provided with welding bevels (4).

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