A vacuum brazing method for a conical honeycomb inner ring assembly

Abstract

The application discloses a kind of vacuum brazing methods of conical honeycomb inner ring assembly, S1: make the conical honeycomb ring of interference fit with the inner surface of support piece, the length interference amount of honeycomb ring is 1-3mm;S2: polishing cleaning;S3: filling adhesive tape brazing material;S4: honeycomb positioning and spot welding;S5: honeycomb brazing;The application does not need to clamp positioning tool, and the clearance between honeycomb ring and support piece during assembly and brazing process is guaranteed by process combination, and the brazing rate of more than 95% of the conical honeycomb inner ring assembly can be obtained by once brazing;Excess honeycomb is used, and the honeycomb interference amount is evenly distributed on the support piece by the center alternating spot welding fixing mode, to form pressure stress on the support piece;Vacuum brazing is carried out by short-time holding and slow cooling process combination, and the synchronous shrinkage of honeycomb and support piece during cooling process is guaranteed by slow cooling process, to reduce the possibility that honeycomb is forced to separate from support piece;At the same time, the holding time is appropriately shortened, so that the time of brazing material above liquidus temperature is reduced, and the corrosion of brazing material to honeycomb is avoided.

Description

Technical Field

[0001] This invention belongs to the field of brazing technology for conical honeycomb inner ring components, specifically relating to a vacuum brazing method for conical honeycomb inner ring components. Background Technology

[0002] Honeycomb modules are widely used as seals in aero-engines and gas turbines due to their advantages such as light weight, good airtightness, long lifespan, and high safety. They generally consist of two parts: a honeycomb structure and an annular support. Currently, the connection is mainly achieved through spot welding followed by vacuum brazing. The brazing success rate of honeycomb modules largely depends on the gap between the honeycomb and the support. Engines contain numerous conical honeycomb inner ring components. Using tooling for clamping and positioning is complex and ineffective due to the varying angles of the component's different surfaces. Without tooling, the honeycomb on the inner surface cannot be constrained by the external support during brazing. Furthermore, the difference in wall thickness between the two leads to significant differences in their cooling rates. When the honeycomb contracts, areas with poor spot welding are easily pulled apart, even straightened, creating a large gap between the honeycomb and the support, ultimately resulting in numerous incompletely brazed areas after brazing. For areas with large gaps that are not fully penetrated, the gaps between the honeycomb foil strips are filled by the solidified and hardened brazing filler metal, making it impossible to shrink the brazing gap by deforming and fitting with the support again. Therefore, it is impossible to perform repair welding, resulting in the direct scrapping of the parts.

[0003] Therefore, this invention proposes a vacuum brazing method for a conical honeycomb inner ring assembly. Summary of the Invention

[0004] The purpose of this invention is to provide a vacuum brazing method for a conical honeycomb inner ring assembly to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a vacuum brazing method for a conical honeycomb inner ring assembly, the specific steps of which include:

[0006] S1: Honeycomb fabrication: Fabricate a tapered honeycomb ring that is interference-fitted with the inner surface of the support component. The length interference of the honeycomb ring is 1-3mm.

[0007] S2: Grinding and cleaning: Use sandpaper to grind the support and honeycomb surfaces to be brazed until a metallic luster is exposed.

[0008] Then clean with acetone;

[0009] S3: Filling with adhesive brazing material: Place the adhesive brazing material on the honeycomb ring brazing surface, use a rolling pin to press the adhesive brazing material evenly into the honeycomb core, scrape off the excess brazing material on the surface to be brazed, so that the surface to be brazed is exposed with a metallic luster.

[0010] S4: Cellular positioning and spot welding: Pre-assemble the cellular rings to determine their assembly positions on the support, and then mark them on the support; First round of spot welding: Perform the first spot welding at the splicing point of the cellular rings, then rotate 180° for spot welding, rotate 90° for spot welding, and rotate 180° for spot welding again. After that, the first weld point of each round of spot welding is randomly selected at the position between two adjacent weld points in the previous round, and then rotate clockwise to perform spot welding at the position between two adjacent weld points in the previous round, until all the positions between two adjacent weld points in the previous round are spot welded, before proceeding to the next round of spot welding. Perform multiple rounds of spot welding in the above manner until all positions of the cellular rings are covered by weld points;

[0011] S5: Cellular Brazing: Cellular brazing is performed using a short-time heat preservation and slow cooling process. After the heat preservation is completed, the cooling rate is controlled at 3-7℃ / min through a program. When the temperature drops to the liquidus line of the brazing filler metal, the cooling rate is controlled at 8-14℃ / min through a program. When the temperature reaches 50-100℃ below the solidus line of the brazing filler metal, furnace cooling or rapid cooling with argon gas is selected according to the heat treatment requirements of the support component.

[0012] Preferably, in step S4, the position of the honeycomb is adjusted each time spot welding is performed, so that the honeycomb deformed axially due to interference is within the assembly position range, and the interference of the honeycomb on both sides of the weld point is basically equal.

[0013] Preferably, if the honeycomb is wide, spot welding is performed on the honeycomb with the largest diameter first. After spot welding the first ring, spot welding is performed on the next ring along the direction of diameter reduction. The spot welding method is the same as the first ring, and the spot welding position is located at the junction of two adjacent weld points in the previous ring.

[0014] Preferably, in step S5, in order to prevent honeycomb erosion caused by the brazing filler metal being above the liquidus temperature for too long, the heat preservation time is shortened to 4-8 minutes.

[0015] Preferably, in step S5, the vacuum level throughout the brazing process is better than 4*10. -2 Pa.

[0016] Compared with the prior art, the beneficial effects of the present invention are: the present invention does not require clamping and positioning fixtures, and through interference honeycomb, alternating center spot welding fixing method, short-time heat preservation and slow cooling process combination, the gap between the honeycomb ring and the support component during assembly and brazing can be controlled, and a conical honeycomb inner ring assembly with a brazing rate of more than 95% can be obtained in one brazing.

[0017] Using a honeycomb ring that is interference-fitted with the support, the interference of the honeycomb is evenly distributed on the support by alternating spot welding at the center, so that the honeycomb forms compressive stress on the support, ensuring a tight fit between the honeycomb ring and the support. Furthermore, by compressing the honeycomb in advance, the shrinkage of the honeycomb during the brazing process is reduced.

[0018] Vacuum brazing is performed using a combination of short-time heat preservation and slow cooling. The cooling rate of the honeycomb module is controlled by a program to ensure that the honeycomb and the support shrink synchronously during the cooling process. Argon rapid cooling is then performed after the brazing seam has reached a certain strength, which reduces the possibility of the honeycomb detaching from the support under stress. At the same time, the heat preservation time is appropriately shortened to reduce the time that the brazing filler metal is above the liquidus temperature, thus avoiding the corrosion of the honeycomb by the brazing filler metal. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of vacuum brazing according to the present invention. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Please see Figure 1 This invention provides a technical solution: a vacuum brazing method for a conical honeycomb inner ring assembly, the specific steps of which include:

[0022] S1: Honeycomb fabrication: Fabricate a tapered honeycomb ring that is interference-fitted with the inner surface of the support component. The support component is made of GH4648 material, the honeycomb ring is made of GH3030 material, and the interference of the honeycomb ring length is 2mm.

[0023] S2: Grinding and cleaning: Use 400-grit sandpaper to grind the support and honeycomb surface to be brazed until the metal luster is exposed, and then clean with acetone;

[0024] S3: Filling with adhesive brazing tape: Place the adhesive brazing tape on the brazing surface of the honeycomb ring, and use a rolling pin to evenly roll and press the 0.5mm thick adhesive brazing tape into the honeycomb core. Scrape off the excess brazing tape on the surface to be brazed to expose the metallic luster.

[0025] S4: Cellular positioning and spot welding: Pre-assemble the cellular rings to determine their assembly positions on the support, and then mark them on the support; First round of spot welding: Perform the first spot welding at the splicing point of the cellular rings, then rotate 180° for spot welding, rotate 90° for spot welding, and rotate 180° for spot welding again. After that, the first weld point of each round of spot welding is randomly selected at the position between two adjacent weld points in the previous round, and then rotate clockwise to perform spot welding at the position between two adjacent weld points in the previous round, until all the positions between two adjacent weld points in the previous round are spot welded, before proceeding to the next round of spot welding. Perform multiple rounds of spot welding in the above manner until all positions of the cellular rings are covered by weld points;

[0026] S5: Cellular Brazing: Cellular brazing is performed using a short-time heat preservation and slow cooling process. The brazing process is as follows: 90 min to 450℃, heat preservation for 30 min, 49 min to 940℃, heat preservation for 20 min, 16 min to 1100℃, heat preservation for 5 min, after the heat preservation is completed, cool to 1030℃ at a rate of 7℃ / min, then cool to 920℃ at a rate of 11℃ / min, and then rapidly cool to below 150℃ with argon gas before being removed from the furnace.

[0027] In this embodiment, preferably, in step S4, the position of the honeycomb is adjusted each time spot welding is performed, so that the honeycomb deformed axially due to interference is within the assembly position range, and the interference of the honeycomb on both sides of the weld point is basically equal.

[0028] In this embodiment, preferably, if the honeycomb is wide, spot welding is performed on the honeycomb with the largest diameter first. After spot welding the first circle, spot welding is performed on the next circle along the diameter reduction direction. The spot welding method is the same as the first circle, and the spot welding position is located at the junction of two adjacent weld points in the previous circle.

[0029] In this embodiment, preferably, in step S5, the vacuum level throughout the brazing process is better than 4*10. -2 Pa.

[0030] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A vacuum brazing method for a conical honeycomb inner ring assembly, characterized in that, The specific steps include: S1: Honeycomb fabrication: Fabricate a tapered honeycomb ring that is interference-fitted with the inner surface of the support component. The length interference of the honeycomb ring is 1-3mm. S2: Grinding and cleaning: Grind the support and honeycomb surface to be brazed with sandpaper until the metal luster is exposed, and then clean with acetone; S3: Filling with adhesive brazing material: Place the adhesive brazing material on the honeycomb ring brazing surface, use a rolling pin to press the adhesive brazing material evenly into the honeycomb core, scrape off the excess brazing material on the surface to be brazed, so that the surface to be brazed is exposed with a metallic luster. S4: Cellular positioning and spot welding: Pre-assemble the cellular rings to determine their assembly positions on the support, and then mark them on the support; First round of spot welding: Perform the first spot welding at the splicing point of the cellular rings, then rotate 180° for spot welding, rotate 90° for spot welding, and rotate 180° for spot welding again. After that, the first weld point of each round of spot welding is randomly selected at the position between two adjacent weld points in the previous round, and then rotate clockwise to perform spot welding at the position between two adjacent weld points in the previous round, until all the positions between two adjacent weld points in the previous round are spot welded, before proceeding to the next round of spot welding. Perform multiple rounds of spot welding in the above manner until all positions of the cellular rings are covered by weld points; S5: Cellular Brazing: Cellular brazing is performed using a short-time heat preservation and slow cooling process. After the heat preservation is completed, the cooling rate is controlled at 3-7℃ / min through a program. When the temperature drops to the liquidus line of the brazing filler metal, the cooling rate is controlled at 8-14℃ / min through a program. When the temperature reaches 50-100℃ below the solidus line of the brazing filler metal, furnace cooling or rapid cooling with argon gas is selected according to the heat treatment requirements of the support component.

2. The vacuum brazing method for a conical honeycomb inner ring assembly according to claim 1, characterized in that: In step S4, the position of the honeycomb is adjusted each time spot welding is performed so that the honeycomb deformed axially due to interference is within the assembly position range, and the interference of the honeycomb on both sides of the weld point is basically equal.

3. The vacuum brazing method for a conical honeycomb inner ring assembly according to claim 2, characterized in that: If the honeycomb is wide, spot welding should be performed first on the honeycomb with the largest diameter. After spot welding the first ring, spot welding should be performed on the next ring in the direction of diameter reduction. The spot welding method is the same as the first ring, and the spot welding position is located at the junction of two adjacent weld points in the previous ring.

4. The vacuum brazing method for a conical honeycomb inner ring assembly according to claim 1, characterized in that: In step S5, in order to prevent honeycomb erosion caused by the brazing filler metal being above the liquidus temperature for too long, the holding time is shortened to 4-8 minutes.

5. The vacuum brazing method for a conical honeycomb inner ring assembly according to claim 1, characterized in that: In step S5, the vacuum level throughout the brazing process is better than 4*10. -2 Pa.

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