Hollow blade and preparation process thereof

Abstract

The invention discloses a hollow blade preparation process which comprises the following steps: S1, preparing a hollow blade matrix with a cavity; s2, preparing a honeycomb core; s3, according to the preset positions, where the noise reduction holes need to be prepared, on the hollow blade, soluble supporting materials are added into the holes, in the corresponding positions, of the honeycomb core, the soluble supporting materials are cured, and the honeycomb core with an internal support is formed; s4, laying a first adhesive film layer at the bottom of the cavity, assembling the honeycomb core obtained in the step S2 on the first adhesive film layer, and laying a second adhesive film layer at the top of the honeycomb core; s5, bonding a skin cover plate on the second adhesive film layer; s6, curing of the first adhesive film layer and the second adhesive film layer is completed; s7, a noise reduction hole is formed in the skin cover plate according to the preset position; s8, the workpiece obtained in the step S6 is put into a dissolving agent, and the soluble supporting material is removed; and S9, the workpiece is taken out and dried.

Description

Technical Field

[0001] The invention relates to the technical field of noise reduction hole preparation, and in particular to a hollow blade and a preparation process thereof. Background Art

[0002] As the bypass ratio design of turbofan engines continues to increase, fan noise is becoming one of the main noise sources of aircraft engines and even aircraft noise. According to the technical specifications of the International Civil Aviation Organization (ICAO) for aircraft noise certification, the noise level of large civil aircraft is one of the important contents of airworthiness certification, and the noise standards are also constantly improving. The noise level of aircraft engines is directly related to the aircraft airworthiness certificate.

[0003] In order to deal with this problem, civil aircraft and aero-engine manufacturers, as well as scientific research institutes such as universities, have carried out systematic research on engine noise reduction measures to meet noise airworthiness requirements. Since the emergence of jet aircraft engines, the acoustic lining structure has always been the main means of controlling fan noise. At present, large civil aircraft all use multi-stage silencing acoustic linings to meet noise control requirements. For the outlet guide vanes in the fan boost stage, noise reduction holes are designed at specific positions to assist in noise reduction. However, the hole density of the acoustic lining holes is high, the hole making accuracy requirements are high, and the hole making efficiency is low. How to efficiently and high-quality prepare a large number of acoustic lining holes has become one of the key technologies for acoustic lining noise reduction.

[0004] The traditional hole making process for noise reduction has the problems of low hole making accuracy, easy honeycomb damage, surface change, etc., which in turn affects the noise reduction effect. Summary of the invention

[0005] An object of the present invention is to provide a hollow blade preparation process, which can improve the hole making accuracy of the noise reduction holes and ensure the noise reduction effect of the hollow blades.

[0006] The hollow blade preparation process comprises the following steps:

[0007] S1. preparing a hollow blade substrate having a cavity;

[0008] S2, preparing a honeycomb core;

[0009] S3, according to the predetermined positions of the noise reduction holes to be prepared on the hollow blades, adding soluble support materials into the holes of the honeycomb core at the corresponding positions, and solidifying the soluble support materials to form a honeycomb core with internal support;

[0010] 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;

[0011] S5, bonding the skin cover plate on the second adhesive film layer;

[0012] S6, completing the curing of the first adhesive film layer and the second adhesive film layer;

[0013] S7, preparing noise reduction holes on the skin cover plate according to the predetermined positions;

[0014] S8, placing the product obtained in step S6 into a dissolving agent to remove the soluble supporting material;

[0015] S9, taking out the product and drying the product. In one or more embodiments, the hollow blade preparation process further comprises the following steps:

[0016] S10. Use a nondestructive testing method to test the bonding interface between the skin cover plate and the second adhesive film layer to confirm the integrity of the bonding interface.

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

[0018] S11, using a non-destructive testing method to detect whether there is any residual soluble support material in the pores of the honeycomb core, if it is detected that there is any residual soluble support material, repeating steps S8 to S9.

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

[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 dissolving agent is deionized water.

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

[0023] In one or more embodiments, non-destructive testing is performed using ultrasound.

[0024] In one or more embodiments, non-destructive testing is performed using X-rays.

[0025] Another object of the present invention is to provide a hollow blade that can improve the hole making accuracy of the noise reduction holes and ensure the noise reduction effect of the hollow blade.

[0026] The above hollow blades are guide blades of the engine fan boost stage, and are prepared using the hollow blade preparation process as described above.

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

[0028] The above-mentioned hollow blade preparation process proposes an efficient and highly reliable outlet guide vane acoustic liner hole (i.e., noise reduction hole) preparation process of "first curing - adding soluble support - then making holes - removing soluble support". This process inherits the advantages of the traditional preparation process of first curing and then making holes. By adding the process of "adding soluble and removable support materials" on the basis of the traditional process, the support when processing the noise reduction holes above the honeycomb core is enhanced without affecting the overall structure after curing, and the problem of being unable to remove the support after molding and curing due to the use of other physical supports, thereby affecting product performance and quality, is avoided. The hole making accuracy and quality of the noise reduction holes are effectively improved, and the surface deformation of the skin cover is reduced, thereby improving the noise reduction effect of the hollow blade. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0030] Figure 1 It is a flow chart of a hollow blade preparation process according to one embodiment of the present application.

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

[0032] Figure 3 This is a side view of a hollow blade placed in a dissolving agent according to an embodiment of the present application.

[0033] Figure 4 It is a schematic diagram of a hollow blade prepared according to an embodiment of the present application. DETAILED DESCRIPTION

[0034] The present invention is further described below in conjunction with specific embodiments and drawings. More details are described in the following description to facilitate a full understanding of the present invention, but the present invention can obviously be implemented in a variety of other ways different from the description. Those skilled in the art can make similar generalizations and deductions based on actual application situations without violating the connotation of the present invention. Therefore, the protection scope of the present invention should not be limited by the content of this specific embodiment. It should be noted that these and other subsequent drawings are only examples, which are not drawn according to the conditions of equal proportions, and should not be used as a limitation on the protection scope of the actual requirements of the present invention.

[0035] In the fan structure of an aircraft engine, for the aluminum alloy outlet guide vane with a hollow structure, an 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 also play a role in noise reduction in combination with the noise reduction holes at specific positions of the skin cover plate.

[0036] There are two common preparation methods for aluminum alloy guide vanes with hollow structures. The first is a method of curing before making holes: machining the cavity on the guide vane body - laying adhesive film - assembling honeycombs - laying adhesive film - bonding skin cover plates - curing - making noise reduction holes; the second is a method of making holes before curing: making holes on the skin cover plates - machining the cavity on the guide vane body - laying adhesive film - laying honeycombs - laying adhesive film - bonding skin cover plates - curing - thermally breaking through holes.

[0037] The advantages of the first preparation method are precise hole making position, high through-hole rate and obvious noise reduction effect. The disadvantages are that the holes are made after curing, the honeycomb support effect is low, and the aluminum honeycomb under the skin cover and foreign objects trapped in the honeycomb may be damaged, causing damage to the metal of the honeycomb hole wall, affecting the noise reduction performance and corrosion resistance. The advantage of the second preparation method is that the skin cover is easy to make holes and has small deformation, but the position and profile of the cover may change during the curing process. More importantly, the cover film causes blockage of the holes, affecting the noise reduction effect.

[0038] In order to solve the problems existing in the above-mentioned preparation method, according to one aspect of the present application, a hollow blade preparation process is provided. Figure 1 A flowchart of a specific implementation of the hollow blade preparation process is shown. Taking this implementation as an example, the hollow blade preparation process provided by the present application is described. The hollow blade preparation process includes the following steps:

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

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

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

[0042] S4, laying adhesive film layers and assembling the honeycomb core 1. Specifically, laying a first adhesive film layer on the bottom 3 of the cavity according to the design drawing requirements, assembling the honeycomb core 1 obtained in step S2 on the first adhesive film layer, positioning and installing the honeycomb core 1 to the predetermined position in the drawing, and laying a second adhesive film layer on the top of the honeycomb core 1 according to the drawing requirements.

[0043] S5, bonding the skin cover plate 4. Specifically, the skin cover plate 4 can be placed at a predetermined position according to the design drawing by using an auxiliary positioning tool, so as to bond the skin cover plate 4 on 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 adhesive film layer and the second adhesive film layer are cured according to the curing system of the adhesive film layer, the curing temperature is not higher than 127 degrees, and the curing time is not less than 60 minutes.

[0045] S7, preparing the noise reduction holes 5. Specifically, mechanical equipment can be used to prepare the noise reduction holes 5 on the skin cover plate 4 according to the predetermined positions on the design drawings. The hollow blade after the holes are prepared is as follows: Figure 2 and Figure 4 As shown, the holes of the honeycomb core 1 below the area where the noise reduction holes 5 are prepared are correspondingly provided with internal supports formed by soluble supporting materials 2, so that during the preparation process of the noise reduction holes 5, the problems of damage to the honeycomb core 1 and surface changes of the skin cover plate 4 can be effectively avoided, the hole making accuracy and quality of the noise reduction holes 5 are improved, and the noise reduction effect of the blade is guaranteed.

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

[0047] S8, removing the soluble support material 2. Specifically, the product obtained in step S6 is placed in the solvent 6, and the product is turned over under appropriate temperature conditions to dissolve the support material 2, and the soluble support material 2 can be removed. Figure 3 The soluble support material 2 is removed by discharging the soluble support material from the prepared noise reduction hole 5 in the manner shown.

[0048] S9, drying the product. Specifically, after taking the product out of the solvent 6, excess water in the product can be removed by, for example, drying it with a hair dryer or drying it in an oven, and the preparation of the hollow blade 7 is completed after the product is dried.

[0049] In the above embodiment, the soluble support material 2 is a water-soluble support material 2, such as a starch derivative containing glass beads, and the honeycomb core 1 with internal support formed by the material is placed at room temperature (23°C to 35°C) for at least 6 hours to achieve the solidification of the water-soluble support material 2. The dissolving agent 6 is deionized water, and the use of deionized water can achieve the dissolution of the support material 2 at a relatively low temperature (such as room temperature, 23°C to 35°C), thereby avoiding adverse effects on the overall structure of the hollow blade.

[0050] The first film layer can be a thermosetting resin and adhesive that cures at medium temperature, and the second film layer can be a thermosetting resin and adhesive that cures at medium temperature. The curing temperature of the first film layer and the second film layer is not higher than 127 degrees, and the curing time is not less than 60 minutes, ensuring that both films can be stably cured without remelting or over-curing.

[0051] It should be understood that in the hollow blade preparation 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-mentioned embodiment, and can be adjusted according to the specific selected materials, as long as the curing of each component can be completed, effective support can be formed for the skin cover plate 4 in the preparation area of ​​the noise reduction hole 5, 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 preparation process further includes the following steps:

[0053] S10, testing the bonding interface. Specifically, a non-destructive testing method is used to test 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 waves can be used to implement non-destructive testing of the bonding interface. Using ultrasonic waves to test the bonding interface is easy to operate, has strong detectability, and has reliable results.

[0054] S11, check whether there is any residual soluble support material 2. Specifically, a non-destructive testing method is used to detect whether there is any residual soluble support material 2 in the holes of the honeycomb core 1. If it is detected that there is residual, steps S8 to S9 are repeated until the soluble support material 2 is completely removed to avoid the additional weight of the residual material on the hollow blade 7. X-rays can be used to implement non-destructive testing of residual soluble support material 2. Using X-ray testing can facilitate the evaluation of irregular and unpredictable position defects in a non-destructive mode.

[0055] According to another aspect of the present application, a hollow blade 7 is provided. The hollow blade 7 is a guide blade of a boost stage of an engine fan and is prepared using the hollow blade preparation process in one or more of the aforementioned embodiments.

[0056] The above-mentioned hollow blade preparation process proposes an efficient and highly reliable outlet guide vane acoustic liner hole (i.e., noise reduction hole 5) preparation process of "first curing - adding soluble support - then making holes - removing soluble support". This process inherits the advantages of the traditional preparation process of first curing and then making holes. By adding the process of "adding soluble and removable support material 2" on the basis of the traditional process, the support when processing the noise reduction hole 5 on the honeycomb core 1 is enhanced, and it will not affect the overall structure after curing, and avoids the problem of being unable to remove the support after molding and curing due to the use of other physical supports, thereby affecting product performance and quality. The hole making accuracy and hole making quality of the noise reduction hole 5 are effectively improved, and the surface deformation of the skin cover plate 4 is reduced, thereby improving the noise reduction effect of the hollow blade 7.

[0057] Although the present invention is disclosed as above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications without departing from the spirit and scope of the present invention. Therefore, any modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope defined by the claims of the present invention.

Claims

1. A hollow blade preparation process, characterized in that: The following steps are involved: S1. preparing a hollow blade substrate having a cavity; S2, preparing a honeycomb core; S3, according to the predetermined positions of the noise reduction holes to be prepared on the hollow blades, adding soluble support materials into the holes of the honeycomb core at the corresponding positions, and solidifying the soluble support materials 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 the skin cover plate on the second adhesive film layer; S6, completing the curing of the first adhesive film layer and the second adhesive film layer; S7, preparing noise reduction holes on the skin cover plate according to the predetermined positions; S8, placing the product obtained in step S6 into a dissolving agent to remove the soluble supporting material; S9, taking out the product and drying the product.

2. The hollow blade preparation process according to claim 1, characterized in that: The hollow blade preparation process also includes the following steps: S10. Use a nondestructive testing method to test the bonding interface between the skin cover plate and the second adhesive film layer to confirm the integrity of the bonding interface.

3. The hollow blade preparation process according to claim 1, characterized in that: The hollow blade preparation process also includes the following steps: S11, using a non-destructive testing method to detect whether there is any residual soluble support material in the pores of the honeycomb core, if it is detected that there is any residual soluble support material, repeating steps S8 to S9.

4. The hollow blade preparation process according to claim 1, characterized in that: In step S2, the soluble support material is placed at room temperature for at least 6 hours to achieve solidification.

5. The hollow blade preparation process according to claim 1, characterized in that: In step S5, 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 preparation process according to claim 1, characterized in that: The soluble support material is a water-soluble support material, and the dissolving agent is deionized water.

7. The hollow blade preparation process according to claim 1, characterized in that: In step S1, the honeycomb core is prepared from aluminum alloy material.

8. The hollow blade preparation process according to claim 2, characterized in that: Ultrasonic non-destructive testing is performed.

9. The hollow blade preparation process according to claim 3, characterized in that: Non-destructive testing using X-rays.

10. A hollow blade, characterized in that: The hollow blades are guide blades of the engine fan boost stage and are prepared using the hollow blade preparation process described in any one of claims 1 to 9.

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