Method for controlling the gap between ultra-thin sheet metal parts and machined parts during brazing

Abstract

The application discloses a kind of ultra-thin sheet metal piece and machine-made piece combined brazing gap control method, sheet metal piece has inner hole and machine-made piece outer circle adhesion, sheet metal piece inner hole roundness technical requirement is B, machine-made piece outer circle size technical requirement is described control method includes following steps: S1.measure the inner diameter of the inner hole of the sheet metal piece, obtain the minimum value of the inner diameter φMin and the maximum value of the inner diameter φMax;S2.machined parts size φA is carried out according to φMax+x1≤φA≤φMin+x2;S3.sheets and machine-made piece are guaranteed roundness C when being carried, and C<B;S4.after being carried, a circle of thickness D is covered on the welding surface of machine-made piece, and the machine-made piece covered with brazing sheet and sheet are adhered in place to confirm the fitting effect of sheet metal piece and machine-made piece;And D=C;S5.enter subsequent welding process.This control method can effectively control the gap of the welding process, and can be conveniently and accurately checked and judged, improve the one-time machining and welding qualification rate of part, ensure the quality of weld.

Description

Technical Field

[0001] This invention relates to the field of brazing technology for aero-engine parts, specifically to a method for controlling the brazing gap between ultra-thin sheet metal parts and machined parts. Background Technology

[0002] Brazing is a process in which a filler metal with a melting point lower than that of the base metal is heated to its melting temperature, causing the filler metal to flow under capillary action and fill the entire joint gap. The gap at the joint not only affects the weld quality but can even affect the weld strength; therefore, a suitable joint gap is of great significance for improving weld quality.

[0003] The flame tube of a certain type of aircraft engine is composed of thin-walled sheet metal parts and machined circular brazed rings, as shown in the instruction manual. Figure 3 As shown, the brazing part is where the sheet metal part and the machined ring meet. Because the sheet metal part is a thin-walled part (wall thickness is only 0.8mm), its roundness and rigidity are not good, and the gap between the two parts at the joint is difficult to meet the brazing requirements.

[0004] To ensure the quality of the brazing weld in this area, the joint gap needs to be controlled. For high-temperature alloys, the ideal brazing gap is typically 0.02–0.08 mm. In actual production, due to poor roundness of the inner hole at the mating point of the sheet metal parts, the opening may be smaller than the middle section, making it impossible to insert a feeler gauge during fitting. This results in a large gap in the middle of the mating area, requiring repeated rework to ensure the correct brazing gap. Furthermore, uneven gap distribution leads to poor brazing weld quality; excessively large gaps make it difficult for the brazing filler metal to fill the area, increasing the risk of leakage and severely impacting the brazing pass rate.

[0005] Patent CN113305390A discloses a vacuum brazing method for interference fit gaps, comprising a first assembly, a second assembly, and a brazing filler metal bath, including the following steps: selecting workpieces; cleaning and drying; assembling workpieces; and brazing in a furnace. This vacuum brazing method for interference fit gaps utilizes the brazing filler metal bath between the first and second assemblies to fix two brazing filler metal rings. By utilizing the difference in thermal expansion coefficients of different materials and controlling the interference fit, the difficult-to-control welding gap can be controlled, resulting in uniform welds, improved dimensional accuracy, guaranteed welding quality, and reduced product scrap rates. The method is simple in structure, easy to operate, and innovates existing methods for controlling weld uniformity in vacuum welding.

[0006] Although the aforementioned patent also designs for brazing gaps, embedding a brazing ring between the first and second assemblies, it sets up a brazing groove to fix the brazing ring. This is not applicable to the brazing design of the flame tube structure on an aero-engine. Furthermore, the first assembly of this patent is not a thin-walled part, and it does not have the defects of large differences in roundness at the opening, middle and root of thin-walled sheet metal parts on the flame tube. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to overcome the defects of the prior art and provide a method for controlling the brazing gap of an ultra-thin sheet metal part and a machined part combination that can effectively control the gap at the welding point during the processing.

[0008] The objective of this invention is achieved through the following technical solution:

[0009] A method for controlling the brazing gap of an ultra-thin sheet metal part combined with a machined part, wherein the sheet metal part has an inner hole that fits with the outer ring of the machined part, the roundness technical requirement of the inner hole of the sheet metal part is B, and the dimensional technical requirement of the outer ring of the machined part is [missing information]. The control method includes the following steps:

[0010] S1. Measure the inner diameter of the sheet metal part at three points: the opening, the middle, and the root, to obtain the minimum inner diameter φMin and the maximum inner diameter φMax;

[0011] S2. The dimensions φA of machined parts for vehicle assembly shall be based on φMax+x1≤φA≤φMin+x2;

[0012] S3. When assembling sheet metal parts and machined parts, ensure roundness C, and C <B;

[0013] S4. After the parts are assembled, a brazing filler metal sheet of thickness D is placed around the welding surface of the machined parts, and the machined parts covered with the brazing filler metal sheet are then fitted into place with the sheet metal parts to confirm the fit between the sheet metal parts and the machined parts; and D = C;

[0014] S5. Proceed to the subsequent welding process.

[0015] Furthermore, the roundness requirement B for the inner hole of the sheet metal part is ensured by mechanical spinning.

[0016] Furthermore, B is set to 0.05 mm, and C is set to 0.04 mm.

[0017] Furthermore, the solder material is BNi82C2rSiB.

[0018] Furthermore, in S4, proper bonding means that after the machined part and the sheet metal part are bonded, the bonded part is inverted to the opening, middle and root of the sheet metal part in a bottom-up sequence. At this time, the machined part does not fall off automatically, but by tapping, the machined part and the brazing filler metal can be gradually pushed down and fall off together.

[0019] Furthermore, the welding process in S5 is as follows:

[0020] S51. Use the energy storage spot welding method to spot weld and position the brazing filler metal sheet at the welding location on the machined part;

[0021] S52. After heating the sheet metal parts, assemble the machined parts and spot weld them at multiple points for positioning;

[0022] S53. Apply solder paste to the mating area between the sheet metal part and the machined part, and then bake it.

[0023] S54. Welding in a vacuum furnace.

[0024] Furthermore, the spacing between the solder pads in S51 is 8–12 mm.

[0025] Furthermore, the S52 employs an energy storage spot welding method for spot welding.

[0026] Going a step further, the S52 features symmetrical spot welding at 6 to 8 points.

[0027] Furthermore, the sheet metal parts in S52 are heated to 140–160°C.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] This invention measures the inner diameter of the inner hole at various points in the thin-walled sheet metal part, using the minimum and maximum values ​​as a benchmark, and combines the tolerances of the machined part to match the outer diameter of the machined part to ensure the clearance requirements are met; a brazing filler metal sheet of the same thickness as the roundness requirement during matching is used to cover the outer ring of the machined part, so that the tightness of the mating sheet metal part can be used to judge whether the clearance meets the requirements.

[0030] This control method can effectively control the gap at the welding point during the processing and can be conveniently and accurately inspected and judged. It avoids the need for repeated rework and quality problems caused by non-conforming parts in traditional brazing operations, improves the first-time processing and welding qualification rate of parts, and ensures the quality of welds. Attached Figure Description

[0031] Figure 1 This is a half-sectional view of the sheet metal part described in Example 1;

[0032] Figure 2 This is a cross-sectional view of the machined part described in Example 1;

[0033] Figure 3 This is a schematic diagram of the welding of sheet metal parts and machined parts in Example 1. Detailed Implementation

[0034] To clearly illustrate the technical features of this solution, the following detailed description, in conjunction with the accompanying drawings, will explain the technical solution in detail.

[0035] Many specific details are set forth in the following description in order to provide a full understanding of this application. However, this application may also be implemented in other ways different from those described herein. Therefore, the scope of protection of this application is not limited to the specific embodiments disclosed below.

[0036] Furthermore, it should be understood in the description of this application that the terms "center," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "axial," "radial," and "circumferential," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this application 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, and therefore should not be construed as a limitation on this application. In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0037] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0038] In this application, unless otherwise expressly specified and limited, the "above" or "below" of the second feature can mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. In the description of this specification, references to terms such as "an embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described can be combined in any suitable manner in one or more embodiments or examples.

[0039] Example 1

[0040] A method for controlling the brazing gap of an ultra-thin sheet metal part and a machined part assembly for an aero-engine flame tube is provided. The sheet metal part structure is as follows: Figure 1 As shown, the structure of the machined part is as follows: Figure 2As shown, the sheet metal part has an inner hole that fits into the outer ring of the machined part. The technical requirement for the roundness of the inner hole of the sheet metal part is 0.05. Before assembly, an additional machining process, spinning and straightening, is added to ensure the roundness and diameter of the sheet metal part are 0.05mm. The technical requirements for the outer ring dimensions of the machined part are... The control method includes the following steps:

[0041] S1. Measure the actual inner diameter of the sheet metal part at three points: the opening, the middle, and the root, to obtain its minimum inner diameter φMin and maximum inner diameter φMax;

[0042] S2. The dimensions φA of the machined parts for vehicle assembly shall be φMax-0.08≤φA≤φMin-0.04 to ensure the clearance requirements are met;

[0043] S3. Before machining sheet metal parts and machined parts, ensure that the parts are easy to clamp, ensure that the roundness is not greater than 0.04, and do not use soft jaws to hold them tight. Machining fixtures must be used for machining.

[0044] S4. After the parts are assembled, cover the welding surface of the machined parts with a 0.04mm thick brazing filler metal sheet of material BNi82C2rSiB according to the brazing surface size, and then fully fit the machined parts covered with the brazing filler metal sheet to the sheet metal parts to confirm the fit between the sheet metal parts and the machined parts.

[0045] In this context, "proper fitting" refers to the following: after the machined part and the sheet metal part are fitted together, the fitted part is inverted and positioned from bottom to top at the opening, middle, and root of the sheet metal part, supporting the sheet metal part. At this point, the machined part should not fall off immediately, nor should it fall off even when struck forcefully due to interference fit. The requirement is met when the outer ring of the machined part gradually slides down when struck with a little force, and after several strikes, the entire ring of the machined part falls off together with the brazing filler metal.

[0046] S5. Proceed to the subsequent welding process:

[0047] First, following step S4, after mating, pack the sheet metal parts and machined parts separately in packaging bags to ensure proper clearance. Before welding, clean the joint with a clean white cloth dampened with acetone, and then proceed with the welding process:

[0048] S51. Use the energy storage spot welding method to spot weld and position the brazing filler metal sheets at the welding location on the machined part. The filler metal sheets are densely positioned around the entire circle, and the spot welding spacing is 8mm to ensure that they will not come off.

[0049] S52. After heating the sheet metal parts to 140°C, assemble the machined parts and use the energy storage spot welding method to spot weld and position them at multiple points. In this embodiment, the spot welding is symmetrical at 6 to 8 points.

[0050] S53. Apply solder paste to the mating area between the sheet metal part and the machined part, and then bake it in the oven;

[0051] S54. After baking, place the mating parts into a vacuum furnace for welding.

[0052] This control method can effectively control the gap at the welding point during the processing and can be conveniently and accurately inspected and judged, thereby improving the first-time processing and welding qualification rate of parts and ensuring the quality of welds.

[0053] Example 2

[0054] A method for controlling the brazing gap of an ultra-thin sheet metal part combined with a machined part, wherein the sheet metal part structure is as follows: Figure 1 As shown, the structure of the machined part is as follows: Figure 2 As shown, the sheet metal part has an inner hole that fits into the outer ring of the machined part. The technical requirement for the roundness of the inner hole of the sheet metal part is 0.05. Before assembly, an additional machining process, spinning and straightening, is added to ensure the roundness and diameter of the sheet metal part are 0.05mm. The technical requirements for the outer ring dimensions of the machined part are... The control method includes the following steps:

[0055] S1. Measure the actual inner diameter of the sheet metal part at three points: the opening, the middle, and the root, to obtain its minimum inner diameter φMin and maximum inner diameter φMax;

[0056] S2. The dimensions φA of the machined parts for vehicle assembly shall be φMax-0.08≤φA≤φMin-0.04 to ensure the clearance requirements are met;

[0057] S3. Before machining sheet metal parts and machined parts, ensure that the parts are easy to clamp, ensure that the roundness is not greater than 0.04, and do not use soft jaws to hold them tight. Machining fixtures must be used for machining.

[0058] S4. After the parts are assembled, cover the welding surface of the machined parts with a 0.04mm thick brazing filler metal sheet of material BNi82C2rSiB according to the brazing surface size, and then fully fit the machined parts covered with the brazing filler metal sheet to the sheet metal parts to confirm the fit between the sheet metal parts and the machined parts.

[0059] In this context, "proper fitting" refers to the following: after the machined part and the sheet metal part are fitted together, the fitted part is inverted and positioned from bottom to top at the opening, middle, and root of the sheet metal part, supporting the sheet metal part. At this point, the machined part should not fall off immediately, nor should it fall off even when struck forcefully due to interference fit. The requirement is met when the outer ring of the machined part gradually slides down when struck with a little force, and after several strikes, the entire ring of the machined part falls off together with the brazing filler metal.

[0060] S5. Proceed to the subsequent welding process:

[0061] First, following step S4, after mating, pack the sheet metal parts and machined parts separately in packaging bags to ensure proper clearance. Before welding, clean the joint with a clean white cloth dampened with acetone, and then proceed with the welding process:

[0062] S51. The brazing filler metal sheet is spot-welded and positioned at the location to be welded on the machined part using the energy storage spot welding method. The filler metal sheet is densely positioned around the entire circle. The difference between this embodiment and embodiment 1 is that the spot welding spacing of the brazing filler metal sheet is 10mm.

[0063] S52. After heating the sheet metal parts to 140°C, assemble the machined parts and use the energy storage spot welding method to spot weld and position them at multiple points. In this embodiment, the spot welding is symmetrical at 6 to 8 points.

[0064] S53. Apply solder paste to the mating area between the sheet metal part and the machined part, and then bake it in the oven;

[0065] S54. After baking, place the mating parts into a vacuum furnace for welding.

[0066] Example 3

[0067] A method for controlling the brazing gap of an ultra-thin sheet metal part combined with a machined part is provided, wherein the sheet metal part structure is as follows: Figure 1 As shown, the structure of the machined part is as follows: Figure 2 As shown, the sheet metal part has an inner hole that fits into the outer ring of the machined part. The technical requirement for the roundness of the inner hole of the sheet metal part is 0.05. Before assembly, an additional machining process, spinning and straightening, is added to ensure the roundness and diameter of the sheet metal part are 0.05mm. The technical requirements for the outer ring dimensions of the machined part are... The control method includes the following steps:

[0068] S1. Measure the actual inner diameter of the sheet metal part at three points: the opening, the middle, and the root, to obtain its minimum inner diameter φMin and maximum inner diameter φMax;

[0069] S2. The dimensions φA of the machined parts for vehicle assembly shall be φMax-0.08≤φA≤φMin-0.04 to ensure the clearance requirements are met;

[0070] S3. Before machining sheet metal parts and machined parts, ensure that the parts are easy to clamp, ensure that the roundness is not greater than 0.04, and do not use soft jaws to hold them tight. Machining fixtures must be used for machining.

[0071] S4. After the parts are assembled, cover the welding surface of the machined parts with a 0.04mm thick brazing filler metal sheet of material BNi82C2rSiB according to the brazing surface size, and then fully fit the machined parts covered with the brazing filler metal sheet to the sheet metal parts to confirm the fit between the sheet metal parts and the machined parts.

[0072] In this context, "proper fitting" refers to the following: after the machined part and the sheet metal part are fitted together, the fitted part is inverted and positioned from bottom to top at the opening, middle, and root of the sheet metal part, supporting the sheet metal part. At this point, the machined part should not fall off immediately, nor should it fall off even when struck forcefully due to interference fit. The requirement is met when the outer ring of the machined part gradually slides down when struck with a little force, and after several strikes, the entire ring of the machined part falls off together with the brazing filler metal.

[0073] S5. Proceed to the subsequent welding process:

[0074] First, following step S4, after mating, pack the sheet metal parts and machined parts separately in packaging bags to ensure proper clearance. Before welding, clean the joint with a clean white cloth dampened with acetone, and then proceed with the welding process:

[0075] S51. The brazing filler metal sheets are spot-welded and positioned on the machined part to be welded using the energy storage spot welding method, with dense positioning around the entire circle. The difference between this embodiment and embodiment 1 is that the spot welding spacing of the brazing filler metal sheets is 12mm.

[0076] S52. After heating the sheet metal parts to 140°C, assemble the machined parts and use the energy storage spot welding method to spot weld and position them at multiple points. In this embodiment, the spot welding is symmetrical at 6 to 8 points.

[0077] S53. Apply solder paste to the mating area between the sheet metal part and the machined part, and then bake it in the oven;

[0078] S54. After baking, place the mating parts into a vacuum furnace for welding.

[0079] Example 4

[0080] The difference between this embodiment and embodiment 1 is that in S52, the sheet metal parts are heated to 150°C and then assembled into machined parts.

[0081] Example 5

[0082] The difference between this embodiment and embodiment 1 is that in S52, the sheet metal parts are heated to 160°C and then assembled into machined parts.

[0083] Obviously, the above embodiments are merely examples to clearly illustrate the technical solutions of 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 method for controlling the brazing gap of an ultra-thin sheet metal part combined with a machined part, wherein the sheet metal part has an inner hole that fits with the outer ring of the machined part, the roundness requirement of the inner hole of the sheet metal part is B, and the dimensional requirement of the outer ring of the machined part is [missing information]. Its features are, The control method includes the following steps: S1. Measure the inner diameter of the sheet metal part at three points: the opening, the middle, and the root, to obtain the minimum inner diameter φMin and the maximum inner diameter φMax; S2. The dimensions φA of machined parts for vehicle assembly shall be based on φMax+x1≤φA≤φMin+x2; S3. When assembling sheet metal parts and machined parts, ensure roundness C, and C <B; S4. After the parts are assembled, a brazing filler metal sheet of thickness D is placed around the welding surface of the machined parts, and the machined parts covered with the brazing filler metal sheet are then fitted into place with the sheet metal parts to confirm the fit between the sheet metal parts and the machined parts; and D = C; S5. Proceed to the subsequent welding process.

2. The method for controlling the brazing gap of an ultra-thin sheet metal part and a machined part according to claim 1, characterized in that, The roundness requirement B for the inner hole of sheet metal parts is ensured by mechanical spinning.

3. The method for controlling the brazing gap of an ultra-thin sheet metal part and a machined part according to claim 1, characterized in that, B is 0.05mm and C is 0.04mm.

4. The method for controlling the brazing gap of an ultra-thin sheet metal part and a machined part according to claim 1, characterized in that, The solder material is BNi82C2rSiB.

5. The method for controlling the brazing gap of an ultra-thin sheet metal part and a machined part according to claim 1, characterized in that, In S4, proper bonding means that after the machined part and the sheet metal part are bonded, the bonded part is inverted to the opening, middle and root of the sheet metal part in a bottom-up sequence. At this time, the machined part will not fall off automatically, but by tapping, the machined part and the brazing filler metal can be gradually pushed down and fall off together.

6. The method for controlling the brazing gap of an ultra-thin sheet metal part and a machined part according to claim 1, characterized in that, The welding process in S5 is as follows: S51. Use the energy storage spot welding method to spot weld and position the brazing filler metal sheet at the welding location on the machined part; S52. After heating the sheet metal parts, assemble the machined parts and spot weld them at multiple points for positioning; S53. Apply solder paste to the mating area between the sheet metal part and the machined part, and then bake it. S54. Welding in a vacuum furnace.

7. The method for controlling the brazing gap of an ultra-thin sheet metal part and a machined part according to claim 6, characterized in that, The spacing between the brazing filler metal pieces in S51 is 8–12 mm.

8. The method for controlling the brazing gap of an ultra-thin sheet metal part and a machined part according to claim 6, characterized in that, S52 uses an energy storage spot welding method for spot welding.

9. The method for controlling the brazing gap of an ultra-thin sheet metal part and a machined part according to claim 8, characterized in that, In S52, spot welding is done symmetrically at 6 to 8 points.

10. The method for controlling the brazing gap of an ultra-thin sheet metal part and a machined part according to claim 6, characterized in that, In S52, sheet metal parts are heated to 140-160°C.

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