Hollow blade and process for manufacturing thereof

Abstract

A hollow blade manufacturing process, comprising the following steps: S1, preparing a hollow blade base body with a cavity; S2, preparing a honeycomb core; S3, according to a predetermined position where a noise reduction hole needs to be prepared on the hollow blade, adding soluble support material into a hole of the honeycomb core at the corresponding position, and solidifying the soluble support material to form a honeycomb core with internal support; S4, laying a first adhesive film layer on the bottom of the cavity, assembling the honeycomb core obtained in step S2 on the first adhesive film layer, and laying a second adhesive film layer on the top of the honeycomb core; S5, bonding a skin cover plate on the second adhesive film layer; S6, completing the solidification of the first adhesive film layer and the second adhesive film layer; S7, preparing a noise reduction hole on the skin cover plate according to the predetermined position; S8, putting the product obtained in step S6 into a dissolving agent to remove the soluble support material; S9, taking out the product and drying the product.

Description

Technical Field

[0001] This invention relates to the field of noise reduction hole preparation technology, specifically to a hollow blade and its preparation process. Background Technology

[0002] As the bypass ratio of turbofan engines continues to increase, fan noise is increasingly becoming one of the main noise sources for aircraft engines and even aircraft. According to the technical specifications for aircraft noise certification issued by the International Civil Aviation Organization (ICAO), the noise level of large civil aircraft is a crucial aspect of airworthiness certification, and noise standards are constantly being raised. The noise level of aircraft engines is directly related to aircraft airworthiness certification.

[0003] To address this issue, civil aircraft and aero-engine manufacturers, as well as universities and research institutions, have conducted systematic research on engine noise reduction measures to meet noise compliance requirements. Since the advent of jet engines, acoustic liner structures have been the primary means of controlling fan noise. Currently, large civil aircraft employ multi-stage silencing liner structures to meet noise control requirements. Noise-reducing holes are designed at specific locations on the outlet guide vanes of the fan turbocharger stage, which can play a supplementary role in noise reduction. However, the acoustic liner holes require high density, high precision, and low efficiency. Therefore, how to efficiently and effectively manufacture a large number of acoustic liner holes has become one of the key technologies for acoustic liner noise reduction.

[0004] Traditional noise reduction hole manufacturing processes suffer from low hole precision, which can easily lead to honeycomb damage and surface changes, thus affecting the noise reduction effect. Summary of the Invention

[0005] One objective of this invention is to provide a hollow blade manufacturing process that can improve the drilling accuracy of noise reduction holes and ensure the noise reduction effect of hollow blades.

[0006] The above-mentioned hollow blade manufacturing process includes the following steps:

[0007] S1. Prepare a hollow blade substrate with cavities;

[0008] S2. Preparation of honeycomb core;

[0009] S3. According to the predetermined position where noise reduction holes need to be prepared on the hollow blade, add soluble support material into the hole of the honeycomb core at the corresponding position, and let the soluble support material solidify to form a honeycomb core with internal support.

[0010] S4. A first adhesive film layer is laid at the bottom of the cavity, the honeycomb core obtained in step S2 is assembled on the first adhesive film layer, and a second adhesive film layer is laid on the top of the honeycomb core.

[0011] S5. Adhere the skin cover plate to the second adhesive film layer;

[0012] S6. Complete the curing of the first adhesive film layer and the second adhesive film layer;

[0013] S7. Noise reduction holes are prepared on the skin cover plate according to the predetermined positions;

[0014] S8. Place the part obtained in step S6 into the solvent to remove the soluble support material;

[0015] S9. Remove the part and dry it. In one or more embodiments, the hollow blade manufacturing process further includes the following steps:

[0016] S10. The bonding interface between the skin cover plate and the second adhesive film layer is tested using a non-destructive testing method to confirm the integrity of the bonding interface.

[0017] In one or more embodiments, the hollow blade manufacturing process further includes the following steps:

[0018] S11. Use non-destructive testing to detect whether there is residual soluble support material in the pores of the honeycomb core. If residue is detected, repeat steps S8 to S9.

[0019] In one or more embodiments, in step S2, the soluble support material is left at room temperature for at least 6 hours to cure.

[0020] In one or more embodiments, in step S5, the curing temperature of the first adhesive film layer and the second adhesive film layer is not higher than 127 degrees.

[0021] In one or more embodiments, the soluble support material is a water-soluble support material, and the solvent is deionized water.

[0022] In one or more embodiments, in step S1, the honeycomb core is made of aluminum alloy material.

[0023] In one or more embodiments, ultrasonic waves are used to perform non-destructive testing.

[0024] In one or more embodiments, X-rays are used to perform non-destructive testing.

[0025] Another objective of this invention is to provide a hollow blade that can improve the drilling accuracy of noise reduction holes and ensure the noise reduction effect of the hollow blade.

[0026] The hollow blades mentioned above are guide vanes for the engine fan turbocharger stage, and are prepared using the hollow blade manufacturing process described above.

[0027] Compared with the prior art, the present invention has at least the following beneficial effects:

[0028] The aforementioned hollow blade manufacturing process proposes a highly efficient and reliable process for preparing the acoustic liner hole (i.e., noise reduction hole) for the outlet guide vane, which involves "first curing - adding soluble support - then drilling holes - removing soluble support". This process inherits the advantages of the traditional process of first curing and then drilling holes. By adding the step of "adding soluble and removable support material" to the traditional process, the support is enhanced when processing the noise reduction hole above the honeycomb core, without affecting the overall structure after curing. This avoids the problem of not being able to remove the support after molding and curing, which would affect the product performance and quality, caused by using other physical supports. It effectively improves the drilling accuracy and quality of the noise reduction hole, reduces the surface deformation of the skin cover plate, and thus improves the noise reduction effect of the hollow blade. Attached Figure Description

[0029] The above and other features, properties and advantages of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings and embodiments, wherein:

[0030] Figure 1 This is a flowchart of a hollow blade manufacturing process according to an embodiment of this application.

[0031] Figure 2 This is a side view of a hollow blade according to an embodiment of this application.

[0032] Figure 3 This is a side view of a hollow blade placed in a solvent according to an embodiment of this application.

[0033] Figure 4 This is a schematic diagram of a hollow blade prepared according to an embodiment of this application. Detailed Implementation

[0034] The present invention will be further described below with reference to specific embodiments and accompanying drawings. More details are set forth in the following description to provide a full understanding of the invention. However, the invention can obviously be implemented in many other ways different from those described herein. Those skilled in the art can make similar extensions and derivations based on actual applications without departing from the spirit of the invention. Therefore, the scope of protection of the invention should not be limited by the content of these specific embodiments. It should be noted that these and subsequent accompanying drawings are merely examples and are not drawn to scale, and should not be construed as limiting the actual scope of protection claimed by the invention.

[0035] In the fan structure of aero-engines, for the hollow aluminum alloy outlet guide vanes, aluminum honeycomb is placed in the cavity of the guide vane forging. On the one hand, it can support the aluminum alloy skin cover plate, and on the other hand, it can reduce noise by combining with the noise reduction holes at specific positions of the skin cover plate.

[0036] There are two common methods for manufacturing hollow aluminum alloy guide vanes. The first method is to cure first and then make holes: machining the cavity in the guide vane body -- laying the adhesive film -- assembling the honeycomb -- laying the adhesive film -- bonding the skin cover plate -- curing -- making noise reduction holes; the second method is to make holes first and then cure: making holes in the skin cover plate -- machining the cavity in the guide vane body -- laying the adhesive film -- laying the honeycomb -- laying the adhesive film -- bonding the skin cover plate -- curing -- thermally breaking through the holes.

[0037] The first preparation method has the advantages of precise hole positioning, high permeability, and significant noise reduction effect. However, it has the disadvantage of lower honeycomb support effect after curing and the potential for damage to the aluminum honeycomb under the skin cover plate and foreign matter retention in the honeycomb, which can damage the metal of the honeycomb hole wall and affect the noise reduction performance and corrosion resistance. The second preparation method has the advantages of convenient hole making in the skin cover plate and less deformation. However, the position and shape of the cover plate may change during the curing process. More importantly, the adhesive film on the cover plate can cause pore blockage, affecting the noise reduction effect.

[0038] To address the problems existing in the aforementioned preparation methods, according to one aspect of this application, a process for preparing hollow blades is provided. Figure 1 A flowchart illustrating a specific embodiment of the hollow blade manufacturing process is provided. This embodiment will be used as an example to explain the hollow blade manufacturing process provided in this application. The hollow blade manufacturing process includes the following steps:

[0039] S1. Preparation of hollow blade substrate. Specifically, according to the design drawings, a cavity is formed on a forging made of a material such as aluminum alloy to prepare a hollow blade substrate with a cavity. The cavity can be a groove formed on one side surface of the forging, so that the adhesive film layer, honeycomb core 1 and skin cover plate 4 in the subsequent steps can be placed in it to form a complete hollow blade.

[0040] S2. Preparation of honeycomb core 1. Specifically, the honeycomb material is processed according to the design drawings to obtain honeycomb core 1 that meets the net size requirements. Honeycomb core 1 can be prepared from aluminum alloy material.

[0041] S3. Add soluble support material 2. Specifically, according to the predetermined position where noise reduction holes 5 need to be prepared on the hollow blade, add soluble support material 2 into the hole of the honeycomb core 1 at the corresponding position, and let the soluble support material 2 solidify to form a honeycomb core 1 with internal support, which can support the skin cover plate 4 where holes need to be made in subsequent steps, thereby improving the hole making accuracy.

[0042] S4. Lay out the adhesive film layer and assemble the honeycomb core 1. Specifically, lay out the first adhesive film layer at the bottom 3 of the cavity according to the design drawings, assemble the honeycomb core 1 obtained in step S2 on the first adhesive film layer, position and install the honeycomb core 1 in the predetermined position in the drawings, and after completion, lay out the second adhesive film layer on the top of the honeycomb core 1 according to the drawings.

[0043] S5. Bonding the skin cover plate 4. Specifically, an auxiliary positioning fixture can be used to place the skin cover plate 4 in the predetermined position according to the design drawings, so as to bond the skin cover plate 4 to the second adhesive film layer, improve the bonding accuracy between the second adhesive film layer and the skin cover plate 4, and ensure the integrity of the bonding interface.

[0044] S6. Curing the adhesive film layer. Specifically, the first and second adhesive film layers are cured according to the curing regime. The curing temperature is not higher than 127 degrees Celsius, and the curing time is not less than 60 minutes.

[0045] S7. Prepare noise reduction holes 5. Specifically, mechanical equipment can be used to prepare noise reduction holes 5 on the skin cover plate 4 according to the predetermined positions on the design drawings. The hollow blade after hole preparation is as follows: Figure 2 and Figure 4 As shown, each of the honeycomb core 1 holes below the area where the noise reduction hole 5 is prepared is provided with an internal support formed by a soluble support material 2. This effectively avoids damage to the honeycomb core 1 and changes in the surface of the skin cover plate 4 during the preparation of the noise reduction hole 5, improves the hole-making accuracy and quality of the noise reduction hole 5, and ensures the noise reduction effect of the blade.

[0046] It should be understood that, although the first adhesive layer and the second adhesive layer are not shown in the figure, the first adhesive layer is disposed between the bottom 3 of the hollow blade cavity and the honeycomb core 1, and the second adhesive layer is disposed between the honeycomb core 1 and the skin cover plate 4.

[0047] S8. Remove soluble support material 2. Specifically, place the part obtained in step S6 into solvent 6, and invert the part under appropriate temperature conditions to dissolve the support material 2. Figure 3 The material is discharged from the prepared noise reduction hole 5 in the manner shown, thereby removing the soluble support material 2.

[0048] S9. Drying the part. Specifically, after removing the part from the solvent 6, excess moisture in the part can be removed by means such as blowing it with a hair dryer or placing it in an oven. After drying the part, the preparation of the hollow blade 7 is complete.

[0049] In the above embodiments, the soluble support material 2 is a water-soluble support material, such as a starch derivative containing glass microspheres. The honeycomb core 1 with internal support formed by this material can be cured by placing it at room temperature (23℃~35℃) for at least 6 hours. The solvent 6 is deionized water. Using deionized water can dissolve the support material 2 at a lower temperature (e.g., room temperature, 23℃~35℃), avoiding adverse effects on the overall structure of the hollow blade.

[0050] The first adhesive film layer can be a thermosetting resin and adhesive that cures at medium temperature, and the second adhesive film layer can be a thermosetting resin and adhesive that cures at medium temperature. The curing temperature of the first adhesive film layer and the second adhesive film layer shall not exceed 127 degrees Celsius, and the curing time shall not be less than 60 minutes, to ensure that both adhesive films can be cured stably and that there is no remelting or over-curing phenomenon.

[0051] It should be understood that in the hollow blade manufacturing process, the curing order of the soluble support material 2, the first adhesive film layer and the second adhesive film layer is not limited to the above implementation method. It can be adjusted according to the specific materials selected. As long as the curing of each component can be completed, the skin cover plate 4 of the noise reduction hole 5 preparation area can be effectively supported, and the bonding effect between the skin cover plate 4 and the bottom 3 of the hollow blade cavity can be guaranteed.

[0052] In this embodiment, the hollow blade manufacturing process further includes the following steps:

[0053] S10. Inspect the bonding interface. Specifically, non-destructive testing methods are used to inspect the bonding interface between the skin cover plate 4 and the second adhesive film layer to confirm the integrity of the bonding interface and ensure the quality of the prepared hollow blade 7. Ultrasonic testing can be used for non-destructive testing of the bonding interface. Ultrasonic testing of the bonding interface is easy to operate, highly inspectable, and yields reliable results.

[0054] S11. Detect the presence of residual soluble support material 2. Specifically, use non-destructive testing to detect the presence of residual soluble support material 2 inside the pores of the honeycomb core 1. If residue is detected, repeat steps S8 to S9 until the soluble support material 2 is completely removed to avoid additional weight to the hollow blade 7 due to residual material. X-rays can be used to perform non-destructive testing of residual soluble support material 2. X-ray testing allows for convenient evaluation of irregular and unpredictable location defects in a non-destructive mode.

[0055] According to another aspect of this application, a hollow blade 7 is provided, which is a guide blade for an engine fan booster stage and is prepared using the hollow blade preparation process described in one or more of the foregoing embodiments.

[0056] The above-mentioned hollow blade manufacturing process proposes a highly efficient and reliable process for preparing the outlet guide vane acoustic liner hole (i.e., noise reduction hole 5) by "first curing - adding soluble support - then drilling holes - removing soluble support". This process inherits the advantages of the traditional first curing and then drilling process. By adding the step of "adding soluble and removable support material 2" on the basis of the traditional process, the support is enhanced when processing the noise reduction hole 5 on the honeycomb core 1, and it will not affect the overall structure after curing. It avoids the problem that the support cannot be removed after molding and curing due to the use of other physical supports, which would affect the product performance and quality. It effectively improves the drilling accuracy and drilling quality of the noise reduction hole 5, reduces the surface deformation of the skin cover plate 4, and thus improves the noise reduction effect of the hollow blade 7.

[0057] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Any variations and modifications can be made by those skilled in the art without departing from the spirit and scope of the invention. Therefore, any modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention, without departing from the scope of the invention, fall within the protection scope defined by the claims of the present invention.

Claims

1. A process for manufacturing a hollow blade, characterized in that, Includes the following steps: S1. Prepare a hollow blade substrate with cavities; S2. Preparation of honeycomb core; S3. According to the predetermined position where noise reduction holes need to be prepared on the hollow blade, add soluble support material into the hole of the honeycomb core at the corresponding position, and let the soluble support material solidify to form a honeycomb core with internal support. S4. A first adhesive film layer is laid at the bottom of the cavity, the honeycomb core obtained in step S3 is assembled on the first adhesive film layer, and a second adhesive film layer is laid on the top of the honeycomb core. S5. Adhere the skin cover plate to the second adhesive film layer; S6. Complete the curing of the first adhesive film layer and the second adhesive film layer; S7. Noise reduction holes are prepared on the skin cover plate according to the predetermined positions; S8. Place the part obtained in step S7 into the solvent to remove the soluble support material; S9. Remove the part and dry it.

2. The hollow blade manufacturing process of claim 1, wherein, The hollow blade manufacturing process also includes the following steps: S10. The bonding interface between the skin cover plate and the second adhesive film layer is tested using a non-destructive testing method to confirm the integrity of the bonding interface.

3. The hollow blade manufacturing process of claim 1, wherein, The hollow blade manufacturing process also includes the following steps: S11. Use non-destructive testing to detect whether there is residual soluble support material in the pores of the honeycomb core. If residue is detected, repeat steps S8 to S9.

4. The hollow blade manufacturing process of claim 1, wherein, In step S3, the soluble support material is left at room temperature for at least 6 hours to cure.

5. The hollow blade manufacturing process of claim 1, wherein, In step S6, the curing temperature of the first adhesive film layer and the second adhesive film layer is not higher than 127 degrees.

6. The hollow blade manufacturing process of claim 1, wherein, The soluble support material is a water-soluble support material, and the solvent is deionized water.

7. The hollow blade manufacturing process of claim 1, wherein, In step S2, the honeycomb core is made of aluminum alloy material.

8. The hollow blade manufacturing process of claim 2, wherein, Ultrasonic testing is used for non-destructive testing.

9. The hollow blade manufacturing process of claim 3, wherein, X-rays are used for non-destructive testing.

10. A hollow blade, characterized by The hollow blade is a guide blade for the engine fan turbocharger stage, and is prepared using the hollow blade manufacturing process described in any one of claims 1-9.

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