A vacuum assisted forming method for solving the wrinkling of a torsionally large thickness beam for aerospace

Abstract

The application discloses a vacuum-assisted forming method for solving the wrinkle of a large-thickness beam for aviation, which comprises the following steps: brushing resin, scattering setting powder, laying and locking the edges of a material sheet, hot compaction, flow channel arrangement and packaging and curing, the amount of the setting powder is calculated according to a 3%-6% coefficient to make the scattering process uniform and controllable, the edges of the material sheet are fixed and locked every certain number of layers to slow down the interlayer slip of the material sheet, the material sheet is subjected to low-temperature hot compaction and natural cooling treatment, the interlayer compaction of the whole part is ensured, the wrinkle is convenient to observe and treat in time, the interlayer of the part has high adhesion, the appearance of the part after curing is good, the internal quality is high, the whole operation process is simple and controllable, the cost is low, and the forming difficulty is reduced.

Description

Technical Field

[0001] This invention belongs to the field of composite material molding technology, specifically relating to a vacuum-assisted molding method for solving the problem of wrinkles in thick torsional beams used in aerospace applications. Background Technology

[0002] Vacuum-assisted molding technology is a composite material molding technology that combines vacuum bags with traditional resin transfer molding technology. It features high performance and low cost and has been widely used in automotive and shipbuilding industries. Vacuum-assisted molding processes require only one atmosphere of pressure to cure parts, eliminating the need for additional pressure. This reduces operational difficulty and saves on equipment investment. Furthermore, since only a single-sided mold is needed, it saves on mold manufacturing difficulty and investment compared to resin transfer molding. Aerospace parts need to maintain good physical and chemical properties at high temperatures, so high-grade toughened epoxy resins are often used for high-temperature curing to form composite material structural parts.

[0003] However, the thick torsional beam structure for aerospace applications has complex curvature and large thickness. When using vacuum-assisted forming technology to form the beam structure at high temperature, wrinkles or deformations are likely to occur. The stacking of thick beams is very difficult to form. Therefore, we propose a vacuum-assisted forming method to solve the problem of wrinkles in thick torsional beams for aerospace applications. Summary of the Invention

[0004] The purpose of this invention is to provide a vacuum-assisted forming method for solving the problem of wrinkles in thick torsional beams used in aerospace applications, thereby addressing the issues raised in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a vacuum-assisted forming method for solving the wrinkling problem of thick torsional beams used in aerospace applications, comprising the following steps:

[0006] A. Applying resin:

[0007] At room temperature, apply high-grade toughening epoxy resin evenly to the surface of a single-sided mold, lay a sheet on the high-grade toughening epoxy resin, and use pressure-sensitive tape to fix and lock the edges of the sheet.

[0008] B. Sprinkle setting powder:

[0009] Evenly sprinkle setting powder on the surface of the layer of material laid in step A;

[0010] C. Sheet laying and edge sealing:

[0011] Continue to position and lay several layers of material using a laser projector, and evenly sprinkle setting powder between each layer of material. Every 1-3 layers of material, use pressure-sensitive tape to fix and lock the edges of the material.

[0012] D. Hot compaction:

[0013] After the material sheet is laid, release film, breathable felt and vacuum bag are placed on the surface of the sheet for sealing. Then the whole sheet is sent into the oven for hot compaction. After the hot compaction is completed, it is naturally cooled. The release film, breathable felt and vacuum bag are removed to obtain the semi-formed part of the aerospace torsion thick beam. The surface wrinkles of the semi-formed part of the aerospace torsion thick beam are then checked.

[0014] E. Arrange the flow channels:

[0015] In the case of a semi-formed part of a torsion beam with large thickness for aerospace applications, without any wrinkles on the surface, a layer of release cloth, a layer of guide net, and several injection tubes and dispensing tubes are sequentially arranged on the surface of the semi-formed part of the torsion beam with large thickness for aerospace applications.

[0016] F. Encapsulation and curing:

[0017] Finally, a vacuum bag is placed on the surface of the semi-formed part of the aerospace torsion thick beam, and a vacuum leak test is performed. After the vacuum leak test is completed, it is sent into an oven to cure and form, and the finished aerospace torsion thick beam is obtained.

[0018] Preferably, in steps B and C, the formula for calculating the amount of setting powder sprinkled on the surface of each layer of material is as follows:

[0019] m=ρsa

[0020] Where m represents the amount of setting powder distributed;

[0021] ρ represents the surface density of the material sheet;

[0022] s represents the surface area of ​​the sheet;

[0023] 'a' represents the uniform distribution coefficient of the sizing powder, and a = 3%-6%.

[0024] Preferably, in step C, the edges of the different layers of sheet are staggered.

[0025] Preferably, in step C, pressure-sensitive adhesive tape is used to fix and lock the edges of the sheet every 1-3 layers, and the pressure-sensitive adhesive tapes are staggered.

[0026] Preferably, in step D, the hot compaction temperature is 60-90℃ and the holding time is 10-40 min.

[0027] Preferably, in step D, if wrinkles are found on the surface of the semi-formed aerospace torsion beam with large thickness, the wrinkles are treated with a heat source at a temperature below 60-90°C. The specific process is as follows:

[0028] Cover the surface of the semi-formed aerospace torsion beam with large thickness and wrinkles with a layer of release film, and iron it with a heat source below 60~90°C along the fiber direction until it is visually flat. Then, vacuum seal it for pre-compaction. The pre-compaction vacuum degree is ≥-90kPa and the time is ≥15min. Repeat the above operation according to the wrinkles after pre-compaction until the wrinkles are eliminated.

[0029] Preferably, in step E, there are 1-3 glue injection tubes and glue dispensing tubes.

[0030] Preferably, in step F, the leak detection vacuum degree is -70~-95 kPa, and the leak detection time is 5-10 min.

[0031] Preferably, in step F, the curing temperature is 150-185℃ and the holding time is 2-3h.

[0032] Compared with the prior art, the beneficial effects of the present invention are:

[0033] In this invention, the amount of sizing powder is calculated according to a coefficient of 3%-6% to ensure uniform and controllable spreading process. The edges of the material sheets are fixed and locked at regular intervals to slow down the slippage between material sheets. Medium and low temperature hot compaction and natural cooling treatment ensure the overall interlayer compaction of the part, making it easy to observe wrinkles and deal with them in time. This results in high adhesion between the fiber layers of the part. The cured part has a good appearance, no wrinkles, and high internal quality. The whole operation process is simple and controllable, with low cost and reduced molding difficulty. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the vacuum-assisted forming of the thick torsion beam for aerospace applications according to the present invention.

[0035] In the diagram: 1. Single-sided mold; 2. High-grade toughened epoxy resin; 3. Sheet material; 4. Pressure-sensitive adhesive tape; 5. Setting powder; 6. Release cloth; 7. Guide net; 8. Injection tube; 9. Discharge tube; 10. Vacuum bag. Detailed Implementation

[0036] 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.

[0037] Please see Figure 1 The vacuum-assisted forming method for solving the problem of wrinkles in thick torsional beams for aerospace applications provided by this invention includes the following steps:

[0038] A. Applying resin:

[0039] At room temperature, the high-grade toughening epoxy resin 2 is evenly coated onto the surface of the single-sided mold 1 to make the surface of the single-sided mold 1 have a certain degree of adhesion, which facilitates the laying of the first layer of material sheet and prevents the first layer of material sheet from slipping after contacting the single-sided mold. A layer of material sheet 3 is laid on the high-grade toughening epoxy resin 2, and pressure-sensitive adhesive tape 4 is used to fix and lock the edge of the layer of material sheet 3.

[0040] B. Sprinkle setting powder:

[0041] In step A, the surface of the sheet material 3 is evenly sprinkled with setting powder 5;

[0042] C. Sheet laying and edge sealing:

[0043] The laser projector is used to continue positioning and laying several layers of material sheet 3. The edges of different layers of material sheet 3 are staggered to increase edge friction and avoid resin erosion that causes wrinkles. The setting powder is evenly sprinkled between each layer of material sheet 3. Every 1-3 layers of material sheet 3, the edges of the material sheet 3 are fixed and locked with pressure-sensitive adhesive tape 4. The pressure-sensitive adhesive tape 4 is staggered. The staggered edges of different layers of material sheet determine that the pressure-sensitive adhesive tapes bonded to their surfaces must be staggered to increase edge friction and avoid resin erosion that causes wrinkles.

[0044] The formula for calculating the amount of shaping powder to be sprinkled on the surface of each layer of material is as follows:

[0045] m=ρsa

[0046] Where m represents the amount of setting powder distributed;

[0047] ρ represents the surface density of the material sheet;

[0048] s represents the surface area of ​​the sheet;

[0049] 'a' represents the uniform distribution coefficient of the setting powder, and 'a' = 3%-6%.

[0050] D. Hot compaction:

[0051] After the material sheet 3 is laid, the release film, breathable felt and vacuum bag are placed on the surface in sequence for sealing. Then the whole thing is sent into the oven for hot compaction. The hot compaction temperature is 60-90℃ and the holding time is 10-40min. After the hot compaction is completed, it is allowed to cool naturally. The release film, breathable felt and vacuum bag are removed to obtain the semi-formed part of the aerospace torsion thick beam. The surface wrinkles of the semi-formed part of the aerospace torsion thick beam are then checked.

[0052] If wrinkles are found on the surface of semi-finished torsion beams of large thickness used in aerospace applications, treat the wrinkles with a heat source below 60-90℃. The specific process is as follows:

[0053] Cover the surface of the semi-formed aerospace torsion beam with large thickness that has wrinkles with a layer of release film, and use a heat source below 60~90°C to iron the release film surface along the fiber direction until it is visually flat. Then vacuum seal it for pre-compaction. The pre-compaction vacuum degree is ≥-90kpa and the time is ≥15min. Repeat the above operation according to the wrinkles after pre-compaction until the wrinkles are eliminated.

[0054] E. Arrange the flow channels:

[0055] In the case where the surface of the semi-formed part of the aerospace torsion beam with large thickness is wrinkle-free, a layer of release cloth 6, a layer of guide net 7, and 1-3 injection tubes 8 and dispensing tubes 9 are sequentially arranged on the surface of the semi-formed part of the aerospace torsion beam with large thickness.

[0056] F. Encapsulation and curing:

[0057] Finally, a vacuum bag 10 is placed on the surface of the semi-formed part of the aerospace torsion thick beam, and a vacuum leak test is performed. The vacuum degree is -70~-95kPa and the leak test time is 5-10min. After the vacuum leak test, it is sent into the oven for curing and molding. The curing temperature is 150-185℃ and the heat preservation time is 2-3h to obtain the finished aerospace torsion thick beam.

[0058] In this invention, the amount of sizing powder is calculated according to a coefficient of 3%-6% to ensure uniform and controllable spreading process. The edges of the material sheets are fixed and locked at regular intervals to slow down the slippage between material sheets. Medium and low temperature hot compaction and natural cooling treatment ensure the overall interlayer compaction of the part, making it easy to observe wrinkles and deal with them in time. This results in high adhesion between the fiber layers of the part. The cured part has a good appearance, no wrinkles, and high internal quality. The whole operation process is simple and controllable, with low cost and reduced molding difficulty.

[0059] 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-assisted forming method for solving wrinkles in thick, torsional beams used in aerospace applications, characterized in that, Includes the following steps: A. Applying resin: At room temperature, the advanced toughened epoxy resin (2) is evenly coated onto the surface of the single-sided mold (1), a layer of sheet (3) is laid on the advanced toughened epoxy resin (2), and pressure-sensitive tape (4) is used to fix and lock the edge of the sheet (3). B. Sprinkle setting powder: The surface of the layer of material sheet (3) laid in step A is evenly sprinkled with shaping powder (5); C. Sheet laying and edge sealing: Continue to position and lay several layers of material sheets (3) using a laser projector, and evenly sprinkle shaping powder between each layer of material sheet (3). Use pressure-sensitive tape (4) to fix and lock the edges of the material sheets (3) every 1-3 layers of material sheets (3). D. Hot compaction: Place the release film, breathable felt and vacuum bag on the surface of the laid material sheet (3) in sequence for sealing, and then send the whole into the oven for hot compaction. After the hot compaction is completed, allow it to cool naturally, remove the release film, breathable felt and vacuum bag, and obtain the semi-formed part of the aerospace torsion thick beam, and check the surface wrinkles of the semi-formed part of the aerospace torsion thick beam. E. Arrange the flow channels: In the case where the surface of the semi-formed part of the large-thickness torsion beam for aviation is wrinkle-free, a layer of release cloth (6), a layer of guide net (7), and several injection tubes (8) and dispensing tubes (9) are sequentially arranged on the surface of the semi-formed part of the large-thickness torsion beam for aviation. F. Encapsulation and curing: Finally, a vacuum bag (10) is placed on the surface of the semi-formed part of the aerospace torsion thick beam, and a vacuum leak test is performed. After the vacuum leak test is completed, it is sent into the oven to cure and form, and the finished aerospace torsion thick beam is obtained.

2. The vacuum-assisted forming method for solving wrinkles in thick torsional beams for aerospace applications according to claim 1, characterized in that: In steps B and C, the formula for calculating the amount of setting powder sprinkled on the surface of each layer of material (3) is as follows: m=ρsa Where m represents the amount of setting powder distributed; ρ represents the surface density of the material sheet; s represents the surface area of ​​the sheet; 'a' represents the uniform distribution coefficient of the sizing powder, and a = 3%-6%.

3. The vacuum-assisted forming method for solving wrinkles in thick torsional beams for aerospace applications according to claim 1, characterized in that: In step C, the edges of the different layers of sheet (3) are staggered.

4. The vacuum-assisted forming method for solving wrinkles in thick torsional beams for aerospace applications according to claim 1, characterized in that: In step C, every 1-3 layers of sheet (3), pressure-sensitive tape (4) is used to fix and lock the edges of the sheet (3), and the pressure-sensitive tape (4) are staggered.

5. The vacuum-assisted forming method for solving wrinkles in thick torsional beams for aerospace applications according to claim 1, characterized in that: In step D, the hot compaction temperature is 60-90℃, and the holding time is 10-40 min.

6. The vacuum-assisted forming method for solving wrinkles in thick torsional beams for aerospace applications according to claim 1, characterized in that: In step D, if wrinkles are found on the surface of the semi-formed aerospace torsion beam with large thickness, the wrinkles are treated with a heat source below 60-90°C. The specific process is as follows: Cover the surface of the semi-formed aerospace torsion beam with large thickness and wrinkles with a layer of release film, and iron it with a heat source below 60~90°C along the fiber direction until it is visually flat. Then, vacuum seal it for pre-compaction. The pre-compaction vacuum degree is ≥-90kPa and the time is ≥15min. Repeat the above operation according to the wrinkles after pre-compaction until the wrinkles are eliminated.

7. The vacuum-assisted forming method for solving wrinkles in thick torsional beams for aerospace applications according to claim 1, characterized in that: In step E, there are 1-3 glue injection tubes (8) and glue dispensing tubes (9).

8. The vacuum-assisted forming method for solving wrinkles in thick torsional beams for aerospace applications according to claim 1, characterized in that: In step F, the leak test vacuum degree is -70~-95 kPa, and the leak test time is 5-10 min.

9. The vacuum-assisted forming method for solving wrinkles in thick torsional beams for aerospace applications according to claim 1, characterized in that: In step F, the curing temperature is 150-185℃ and the holding time is 2-3h.

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