Vacuum brazing connection method for diffuser assembly

Abstract

The invention relates to the field of vacuum brazing, in particular to a vacuum brazing connection method for a diffuser assembly. Qualified diffuser parts are obtained through reasonable vacuum brazing process parameters, balance weight requirements, heat preservation cover tool control temperature uniformity and other process elements. And the deformation of the cover plate is controlled by using the inner and outer counterweight rings. The balance weight ring is made of high-strength graphite, the graphite material has good heat storage performance, the temperature consistency of blades below the cover plate can be guaranteed, the graphite is moderate in weight, the height size of a diffuser runner below the cover plate cannot be compressed, and the graphite cannot adhere to the high-temperature alloy cover plate at high temperature. Reasonable welding process parameters guarantee brazing filler metal wetting and brazing seam forming. An optimal brazing process system is determined through process research and exploration, vacuum brazing is carried out at 1060 + / -10 DEG C, brazing filler metal can obtain good wetting and spreading effects, the size requirement of a brazing fillet R is guaranteed, and meanwhile it is guaranteed that the brazing filler metal does not excessively flow, accumulate, immerse and the like.

Description

Technical Field

[0001] The present invention relates to the field of vacuum brazing, and relates to the vacuum brazing connection of a high-temperature alloy diffuser with a plurality of blade structures, and relates to a method for vacuum brazing connection of a diffuser assembly. Background Art

[0002] The radial diffuser in the load section is an important component of the compressor part of an aeroengine. It is assembled by a blade disc and a cover plate and connected by a vacuum brazing method. Dozens of blades are machined on the blade disc, and after being assembled with the blade holes on the cover plate, vacuum brazing welding is required. There are the following two problems in the vacuum brazing process: First, due to the unreasonable selection of the diffuser configuration material and weight, welding quality problems occur. When the configuration material is selected as a metal material, due to the fast heat conduction of the metal, thermal expansion and contraction are verified, resulting in configuration deformation problems, and it is impossible to closely fit the cover plate surface of the diffuser parts. This leads to out-of-tolerance flatness of the cover plate and out-of-tolerance flow channel height after vacuum brazing, and the size requirements cannot be met; Second, due to the uneven temperature field in vacuum brazing, there are differences in the wetting effect of the filler metal flowing at the guide vane weld. Weld beads or filler metal accumulation are likely to occur at the filler metal joints of the blades with lower temperatures, and ablation problems occur at the filler metal joints of the blades with higher temperatures, resulting in unqualified R angles at the filler metal joints at the roots of the blades and the cover plate, and problems of filler metal accumulation and overflow, which will also affect the dimensional accuracy of the flow channel. Summary of the Invention

[0003] Object of the Invention

[0004] The present invention provides a method for vacuum brazing connection of a high-temperature alloy diffuser assembly with a plurality of blade structures, which controls the deformation of parts after welding, ensures dimensional requirements, simultaneously meets the requirements of the R angle of the filler metal joint, prevents the overflow of the filler metal, and meets the requirements of appearance quality inspection.

[0005] Technical Solution

[0006] In order to achieve the above object, a method for vacuum brazing connection of a diffuser assembly is provided. The key is to obtain qualified diffuser parts through process elements such as reasonable vacuum brazing process parameters, weight requirements, and temperature uniformity control of the heat preservation cover tooling.

[0007] A method for vacuum brazing connection of a diffuser assembly includes the following steps:

[0008] S1: The fitter uses sandpaper to clean the welding areas of the diffuser blade disc and the cover plate, removing all oil stains, oxide films and impurities near all blades and blade-shaped holes, ensuring good wettability of the filler metal during the vacuum brazing process;

[0009] S2: Using a laser cutting method, cut the strip-shaped filler metal according to the blade profile program. The cut filler metal needs to be placed in a sealed bag to prevent contamination.

[0010] S3: Ultrasonically clean the diffuser vane disk and the cover plate described in S1 to remove dirt on the part surface. After cleaning, prevent secondary contamination.

[0011] S4: Paste the strip-shaped filler metal described in S2 on the surface of the vane to be welded, and assemble it with the cover plate described in S3. The assembly gap between the vane and the leaf-shaped hole should be ensured to be 0.05 mm - 0.10 mm, and measure and record the flatness and mating gap at the cover plate before welding.

[0012] S5: Place the inner counterweight ring and the outer counterweight ring above the assembled diffuser cover plate. Control the deformation of the cover plate by the weights of the inner counterweight ring and the outer counterweight ring to ensure the flatness requirement after welding. The weights of the counterweight rings should be able to effectively control the deformation of the cover plate under the high temperature of welding and ensure that the flow channel height meets the dimensional requirements.

[0013] S6: Place the assembled diffuser assembly into the protective cover tooling and send it into the furnace. At the same time, place the thermocouple in the furnace into the heat preservation cover to ensure the temperature uniformity of the diffuser during vacuum brazing, so as to control the brazing angle size and the filler metal infiltration.

[0014] S7: Conduct vacuum brazing connection in the state described in S6.

[0015] Further, it also includes S8: After the vacuum brazing is completed, take out the diffuser assembly, measure and record the flatness of the cover plate and the brazing angle R at the root of the vane.

[0016] S9: Perform stress relief treatment on the diffuser assembly described in S8.

[0017] Further, the sandpaper in S1 is specifically 1000#.

[0018] Further, in step S2, the filler metal grade is BNi2 and the thickness is 0.2 mm.

[0019] Further, in step S3, the cleaning time of ultrasonic cleaning is 10 min - 30 min, the ultrasonic frequency is 20 Hz - 40 Hz, and after the ultrasonic cleaning, it should be sent into the furnace for vacuum brazing within 10 h - 16 h.

[0020] Further, in step S5, the counterweight rings placed on the cover plate are divided into an inner ring and an outer ring. The counterweight ring material is high-strength graphite. The mass of the outer ring counterweight is 12 Kg - 16 Kg, and the mass of the inner ring counterweight is 11 Kg - 13 Kg.

[0021] Further, in step S6, the heat preservation cover is a shell component processed from a high-temperature alloy thin plate, with a size of 330 mm × 330 mm, a wall thickness of 1.2 mm, and the heat preservation cover material grade is GH3625.

[0022] Further, in the step S6, the assembled diffuser component needs to be placed in the heat preservation cover, and at the same time, 2 to 3 thermocouples need to be placed, respectively beside the diffuser component and inserted into the flow channel, to monitor the welding temperature of each point of the diffuser parts; the thermocouples should be evenly distributed in the heat preservation cover;

[0023] Further, in the step S7, the vacuum brazing process parameters are as follows: the brazing furnace is evacuated to 1×10 -3 Pa and heated. It is heated at a heating rate of 15°C / min to 920°C, and then held for 5 min to 10 min; then it is heated at a heating rate of 10°C / min to 1020°C to 1060°C ± 10°C for vacuum brazing, and the welding time is 8 min to 12 min; after the welding is completed, it is cooled in the furnace to 400°C ± 10°C, and then cooled to room temperature by filling with argon;

[0024] Further, in the step S8, it is recorded that the flatness of the cover plate is ≤0.3 mm, 0.4 mm ≤ R ≤ 1 mm, and there is no splash, butt joint and immersion flow of the filler metal;

[0025] Further, in the step S9, the stress relieving process is to hold at 350°C to 400°C ± 5°C for 2 h to 10 h.

[0026] Further, the materials of the diffuser disk and the diffuser cover plate to be welded are GH3625.

[0027] The beneficial effects of this application are as follows:

[0028] The technical key of the present invention is: (1) Using two inner and outer counterweight rings to control the deformation of the cover plate. The material of the counterweight ring is high-strength graphite. The graphite material has good heat storage performance, which can ensure the temperature consistency of the blades below the cover plate. Moreover, the weight of the graphite is moderate, which will not compress the height dimension of the diffuser flow channel below the cover plate, and the graphite will not adhere to the high-temperature alloy cover plate at high temperatures; (2) Reasonable welding process parameters ensure the wetting of the filler metal and the formation of the brazing seam. Through process research and exploration, the optimal brazing process system has been determined. Vacuum brazing is carried out at 1060°C ± 10°C, and the filler metal can obtain good wetting and spreading effects, ensuring the dimensional requirements of the brazing fillet R, and at the same time ensuring that the filler metal will not flow excessively, resulting in problems such as accumulation and immersion flow; (3) Using the protective cover tooling to ensure the uniform temperature requirement of the diffuser welding component. Controlling the welding deformation and obtaining a qualified brazing fillet are crucial. The key is that the diffuser component has strict requirements for the uniformity of the temperature field during the welding process. Using the protective cover tooling is to ensure the uniform temperature requirement of each part of the diffuser component during the vacuum brazing process. And the volume of the furnace cavity of the vacuum brazing furnace is much larger than the volume of the protective cover, which can effectively avoid the welding quality problems caused by the temperature deviation in the vacuum brazing furnace. Description of the Drawings

[0029] Figure 1 It is a schematic diagram of vacuum brazing of the diffuser assembly. Specific embodiments

[0030] The present invention will be further described below in conjunction with embodiments. The following only describes some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work belong to the scope of protection of the present invention.

[0031] In order to further illustrate the content of the present invention in detail, the content of the present invention will be further described below in conjunction with the drawings.

[0032] S1: The fitter uses 1000# sandpaper to clean the brazing areas of the diffuser disk and the cover plate, removing all 25 blades and all oil stains, oxide films, impurities, etc. near the blade-shaped holes, ensuring that the brazing filler metal has good wettability during the vacuum brazing process;

[0033] S2: Adopt the laser cutting method to cut the tape-shaped brazing filler metal according to the blade-shaped program. The cut brazing filler metal needs to be placed in a sealed bag to prevent contamination. The brazing filler metal grade is BNi2 and the thickness is 0.2 mm;

[0034] S3: Clean the diffuser blade disk and the cover plate described in S1 by ultrasonic wave to remove dirt such as oil stains on the surface of the parts. After cleaning, the parts should be taken with clean special gloves to prevent secondary contamination. The cleaning time of ultrasonic cleaning is 15 min - 20 min, the ultrasonic frequency is 25 Hz - 30 Hz, and the parts should be put into the furnace for vacuum brazing within 12 h after the ultrasonic cleaning ends;

[0035] S4: Paste the tape-shaped brazing filler metal described in S2 on the brazing area on the blade surface, and assemble it with the cover plate described in S3. The assembly gap between the blade and the blade-shaped hole should be ensured to be 0.07 mm, and the flatness and mating gap at the cover plate should be measured and recorded;

[0036] S5: Place a weight ring above the assembled diffuser cover plate. Control the deformation of the cover plate by the weight of the weight ring to ensure the flatness requirement after welding; The weight ring placed on the cover plate is divided into an inner ring and an outer ring. The material of the weight ring is high-strength graphite. The mass of the outer ring weight is 15 Kg ± 0.5 Kg, and the mass of the inner ring weight is 12.5 Kg ± 0.5 Kg;

[0037] S6: Place the assembled diffuser assembly into the high-temperature alloy protective cover tooling and send it into the furnace. The size of the protective cover is 330 mm × 330 mm and the wall thickness is 1.2 mm. At the same time, 2 - 3 thermocouples need to be placed to monitor the welding temperature at each point inside the protective cover;

[0038] S7: Perform vacuum brazing connection in the state described in S6; the vacuum brazing process parameters are: evacuate the brazing furnace to 1×10 -3 Pa for heating. Heat it to 920°C at a heating rate of 15°C / min, then hold for 5 min to 10 min; then heat it to 1040°C ± 10°C at a heating rate of 10°C / min for vacuum brazing, and the welding time is 8 min to 12 min; after welding, cool it in the furnace to 400°C ± 10°C, and then cool it to room temperature by filling with argon;

[0039] S8: After the vacuum brazing is completed, take out the diffuser assembly, measure and record the flatness of the cover plate and the brazing angle R at the root of the blade; the flatness of the cover plate should meet ≤ 0.3 mm, and R should meet the dimensional requirements of 0.4 mm ≤ R ≤ 1 mm, and there is no splash, butt joint and overflow of the filler metal;

[0040] S9: Perform stress relief treatment on the diffuser assembly described in S8. The stress relief process is to hold at 380°C ± 5°C for 4 h.

[0041] In a possible embodiment, the sandpaper in S1 is specifically 1000#.

[0042] In a possible embodiment, in the step S2, the filler metal grade is BNi2 and the thickness is 0.2 mm;

[0043] In a possible embodiment, in the step S3, the cleaning time of ultrasonic cleaning is 10 min to 30 min, the ultrasonic frequency is 20 Hz to 40 Hz, and after the ultrasonic cleaning is completed, it should be put into the furnace for vacuum brazing within 10 h to 16 h;

[0044] In a possible embodiment, in the step S5, the counterweight rings placed on the cover plate are divided into an inner ring and an outer ring. The counterweight ring material is high-strength graphite. The outer ring counterweight mass is 12 Kg to 16 Kg, and the inner ring counterweight mass is 11 Kg to 13 Kg;

[0045] In a possible embodiment, in the step S6, the heat preservation cover is a shell component processed from a high-temperature alloy thin plate, with dimensions of 330 mm × 330 mm, a wall thickness of 1.2 mm, and the heat preservation cover material grade is GH3625;

[0046] In a possible embodiment, in the step S6, the assembled diffuser assembly needs to be placed in the heat preservation cover, and at the same time, 2 to 3 thermocouples need to be placed, respectively beside the diffuser assembly and inserted into the flow channel to monitor the welding temperature of each point of the diffuser parts; the thermocouples should be evenly distributed in the heat preservation cover;

[0047] In a possible embodiment, in the step S7, the vacuum brazing process parameters are as follows: the brazing furnace is evacuated to 1×10 -3 Pa for heating. It is heated at a heating rate of 15°C / min to 920°C, and then held for 5 min to 10 min; then it is heated at a heating rate of 10°C / min to 1020°C to 1060°C ± 10°C for vacuum brazing, and the welding time is 8 min to 12 min; after the welding is completed, it is cooled in the furnace to 400°C ± 10°C, and then cooled to room temperature by filling with argon;

[0048] In a possible embodiment, in the step S8, it is recorded that the flatness of the cover plate is ≤0.3 mm, 0.4 mm ≤ R ≤ 1 mm, and there is no splash, butt joint, and immersion flow of the filler metal;

[0049] In a possible embodiment, in the step S9, the stress relieving process is to hold at 350°C to 400°C ± 5°C for 2 h to 10 h.

[0050] In a possible embodiment, the materials of the diffuser blisk and the diffuser cover plate to be welded are GH3625.

[0051] Those skilled in the art of the present technology can understand that, unless otherwise defined, all terms (including technical terms and scientific terms) used here have the same meaning as the general understanding of those of ordinary skill in the art to which the present invention belongs. It should also be understood that terms defined in general dictionaries should be understood to have a meaning consistent with the meaning in the context of the prior art, and will not be interpreted with idealized or overly formal meanings unless defined as here. The specific embodiments described above have further elaborated on the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for vacuum brazing connection of a diffuser component, characterized in that, it includes the following steps: Step S1: The fitter uses sandpaper to clean the brazing areas of the diffuser vane disk and the cover plate, removing all oil stains, oxide films and impurities near all blades and leaf-shaped holes to ensure good wettability of the filler metal during the vacuum brazing process; Step S2: Adopt laser cutting method to cut the strip-shaped filler metal according to the leaf shape program. The cut filler metal needs to be placed in a sealed bag to prevent contamination; Step S3: Clean the diffuser vane disk and the cover plate described in Step S1 by ultrasonic wave to remove the dirt on the part surface. After cleaning, prevent secondary contamination; Step S4: Paste the strip-shaped filler metal described in Step S2 on the brazing area on the blade surface, and assemble it with the cover plate described in Step S3. The assembly gap between the blade and the leaf-shaped hole should be ensured to be 0.05mm - 0.10mm, and measure and record the flatness and mating gap at the cover plate before welding; Step S5: Place an inner counterweight ring and an outer counterweight ring above the assembled diffuser cover plate, and use the weights of the inner counterweight ring and the outer counterweight ring to control the deformation of the cover plate to ensure the flatness requirement after welding; the weight of the counterweight ring should be able to effectively control the deformation of the cover plate at high welding temperature to ensure that the flow channel height meets the dimensional requirements; Step S6: Place the assembled diffuser component into the protective cover tooling and send it into the furnace. At the same time, place the thermocouple in the furnace into the heat preservation cover to ensure the temperature uniformity of the diffuser during the vacuum brazing process, so as to control the brazing angle size and the infiltration of the filler metal; Step S7: Carry out vacuum brazing connection in the state of Step S6.

2. The method according to claim 1, characterized in that, it further includes Step S8: After the vacuum brazing is completed, take out the diffuser component, measure and record the flatness of the cover plate and the brazing angle R at the blade root; Step S9: Carry out stress relief treatment on the diffuser component described in Step S8.

3. The method according to claim 2, characterized in that, the sandpaper in Step S1 is specifically 1000#.

4. The method according to claim 3, characterized in that, in Step S2, the filler metal grade is BNi2 and the thickness is 0.2mm.

5. The method according to claim 4, characterized in that, in Step S3, the cleaning time of ultrasonic cleaning is 10min - 30min, the ultrasonic frequency is 20Hz - 40Hz, and the diffuser should be sent into the furnace for vacuum brazing within 10h - 16h after the ultrasonic cleaning ends.

6. The method according to claim 5, characterized in that, in Step S5, the counterweight rings placed on the cover plate are divided into an inner ring and an outer ring. The counterweight ring material is high-strength graphite. The mass of the outer ring counterweight is 12Kg - 16Kg, and the mass of the inner ring counterweight is 11Kg - 13Kg.

7. The method according to claim 6, characterized in that, in Step S6, the heat preservation cover is a shell component processed from a high-temperature alloy thin plate, with a size of 330mm × 330mm and a wall thickness of 1.2mm. The heat preservation cover material grade is GH3625.

8. The method according to claim 7, characterized in that, In the step S6, the assembled diffuser component needs to be placed in the heat preservation cover, and at the same time, 2 to 3 thermocouples need to be placed, respectively beside the diffuser component and inserted into the flow channel, to monitor the welding temperature of each point of the diffuser parts; the thermocouples should be evenly distributed in the heat preservation cover.

9. The method according to claim 8, characterized in that In the step S7, the vacuum brazing process parameters are as follows: the brazing furnace is evacuated to 1×10 -3 Pa for heating; heated at a heating rate of 15°C / min to 920°C, then held for 5 min to 10 min; then heated at a heating rate of 10°C / min to 1020°C to 1060°C ± 10°C for vacuum brazing, and the welding time is 8 min to 12 min; after welding, it is cooled in the furnace to 400°C ± 10°C, and then cooled to room temperature by filling with argon.

10. The method according to claim 9, characterized in that in the step S8, the flatness of the cover plate is recorded as ≤0.3 mm, 0.4 mm ≤ R ≤ 1 mm, and there is no splash, butt joint and immersion flow of the filler metal; in the step S9, the stress relief process is to keep the temperature at 350 °C to 400 °C ± 5 °C for 2 h to 10 h; the materials of the diffuser disk and the diffuser cover plate to be welded are GH3625.

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