A low-cost method for improving the radius (R) quality of composite materials

Abstract

This invention discloses a low-cost method for improving the quality of the radius (R) corners of composite materials. A soft molding strip is added to the R-corner area of ​​L-shaped, C-shaped, and I-shaped parts to prevent bridging by the vacuum bag at the R-corner. This ensures that during high-temperature and high-pressure processes, the R-corner area will not delaminate, accumulate glue, or wrinkle due to the filling of the soft molding strip. Simultaneously, the surface and internal quality of the parts meet design requirements. Furthermore, this method only requires adding a soft molding strip made of Airpad material during encapsulation, eliminating the need for traditional pressure pads or auxiliary tooling, thus reducing manufacturing costs and simplifying the manufacturing process. Additionally, the parts are easily demolded after curing, avoiding damage during the demolding process.

Description

Technical Field

[0001] This invention relates to the field of composite material manufacturing technology, and in particular to a low-cost method for improving the quality of the radius (R) angle of composite materials. Background Technology

[0002] Resin-based carbon fiber composites possess superior properties such as high specific strength and specific stiffness, strong designability, good fatigue fracture resistance, corrosion resistance, and good dimensional stability. They are currently widely used high-performance structural materials in aerospace, transportation, and other fields.

[0003] Composite material molding technology is the foundation and condition for the development of the composite material industry. With the expansion of the application fields of composite materials, the composite material industry has developed rapidly, and new molding methods are constantly emerging.

[0004] Composite material parts include skins (reinforced skins, sandwich skins), frames, beams, I-beams, and simple corner pieces and covers. Whether L-shaped, C-shaped, or I-shaped, they all have some degree of rounded corner structure.

[0005] In the common encapsulation of composite material parts, special attention must be paid to the encapsulation materials in the radius (R) corner area. The release liner and breathable felt need to be disconnected to prevent bridging; and sufficient pleats must be left in the vacuum bag, otherwise the bag may burst during the pressurization of the autoclave during curing, leading to part scrap. If the vacuum bag creates a void in the radius corner area, the quality of that radius corner will also exhibit loosening and delamination. Therefore, even after curing, the radius corner is still highly likely to have various quality problems such as non-destructive defects, edge wrinkling, and unqualified radius values. Summary of the Invention

[0006] The purpose of this invention is to provide a low-cost method for improving the quality of the radius (R) corner of composite materials, so as to solve various quality problems existing in the radius (R) corner area of ​​existing composite material parts.

[0007] To address the aforementioned technical problems, this invention provides a low-cost method for improving the radius (R) quality of composite materials, comprising the following steps:

[0008] Step A: Preparation of soft molding strips;

[0009] Step A1: Lay fiber layers on both sides of the R-angle soft mold forming tooling;

[0010] Step A2: Next, lay rubber strips on the corners of the R-angle soft mold forming tooling, and make the rubber strips overlap with the fiber layers on both sides;

[0011] Step A3: After the tiling is completed, seal and cure it. After curing and demolding, grind and shape it into a soft mold strip.

[0012] Step B: Laying the flexible molding strips;

[0013] Step B1: Apply the prepreg of the part to the R-corner female mold fixture;

[0014] Step B2: Next, place the isolation material inside the R-corner of the prepreg, and then place the soft molding strip on top of the isolation material at the corner of the prepreg.

[0015] Step B3: Then vacuum bag the parts in the order of breathable felt and vacuum bag;

[0016] Step B4: After sealing, place the vacuum nozzle and evacuate to ensure that the insulating material, soft molding strip, breathable felt, and vacuum bag are tightly attached to the part;

[0017] Step C: Curing. Check for vacuum leaks. Once the requirements are met, transfer the product to an autoclave for curing.

[0018] Step D: Demold and remove the part after curing.

[0019] Preferably, the fiber layer laid in step A1 is carbon fiber or glass fiber.

[0020] Preferably, the specific steps of step A1 are as follows: apply three coats of release agent or lay release cloth on the R-corner soft mold forming tooling, and then lay a layer of carbon fiber or glass fiber, extending 5mm outward from the R-corner area.

[0021] Preferably, the rubber strip used in step A2 is an Airpad rubber strip.

[0022] Preferably, the range of the Airpad rubber strip extends 3mm outward from the R-corner area.

[0023] Preferably, after removing the part in step D, the soft molding strip is inspected and reused.

[0024] Preferably, the curing pressure in step A3 is 600kPa to 650kPa, the curing temperature is 175±5℃, and the curing time is not less than 120min. After curing, the temperature drops below 60℃ before the soft molding strip is removed from the autoclave. When the pressure reaches 140kPa during the curing process, the vacuum bag is connected to the atmosphere and kept connected until the curing is complete.

[0025] Compared with the prior art, the beneficial effects of the present invention are:

[0026] 1. This invention adds a soft molding strip to the R-corner area of ​​L-shaped, C-shaped, and I-shaped parts to prevent the vacuum bag from bridging at the R-corner of the parts. This ensures that the R-corner area will not delaminate, accumulate glue, or wrinkle due to the filling of the R-corner by the soft molding strip during high temperature and high pressure processes. At the same time, the surface quality and internal quality of the parts meet the design requirements.

[0027] 2. Compared with traditional R-corner part packaging methods, the method of this invention ensures the R-corner profile of the parts. Simultaneously, the conformal pressure transfer of the soft molding strip makes the curing pressure more uniform during R-corner forming, reducing the risk of wrinkling. Furthermore, the heat transfer during curing is more uniform, thus ensuring the internal quality of the parts remains unaffected. Moreover, the method of this invention only requires the addition of a soft molding strip made of Airpad material during packaging, eliminating the need for traditional pressure pads or auxiliary tooling, reducing manufacturing costs and simplifying the manufacturing process. Additionally, the parts are easily demolded after curing, avoiding damage during the demolding process. Attached Figure Description

[0028] Figure 1 This is a schematic diagram illustrating the preparation of the soft molding strip provided by the present invention;

[0029] Figure 2 This is a schematic diagram of the soft molding strip prepared using the present invention being applied to the R-corner area of ​​a part;

[0030] Figure 3 This diagram illustrates the loose delamination and glue buildup that easily occur in the corner areas of components packaged using traditional methods.

[0031] In the diagram: 1. Part prepreg; 2. Isolation material; 3. Breathable felt; 4. Vacuum bag; 5. Loose layer; 6. Glue accumulation; 10. Round corner soft mold forming tooling; 20. Fiber layer; 30. Rubber strip; 100. Soft mold pressing strip. Detailed Implementation

[0032] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will become clearer from the following description and claims. It should be noted that the drawings are all in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of the present invention.

[0033] In the description of this invention, it should be understood that the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention 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. Therefore, they should not be construed as limitations on this invention.

[0034] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0035] In addition, the features, operations, and characteristics described in the specification can be combined in any suitable manner to form various embodiments. Similarly, the steps or actions described in the method can be rearranged in a manner that is readily apparent to those skilled in the art. Therefore, the various orders in the specification and drawings are merely for the purpose of clearly describing a particular embodiment and are not necessarily required orders, unless otherwise stated that a particular order must be followed. Example

[0036] Traditional parts without flexible molding strips for encapsulation and curing, from Figure 3 As can be seen, parts cured with added soft molding strips are prone to loosening and delamination in the R-corner area 5 and glue accumulation 6. This invention adds soft molding strips to the R-corner areas of L-shaped, C-shaped, and I-shaped parts, preventing the vacuum bag from bridging at the R-corner. This ensures that during high-temperature and high-pressure processes, the R-corner area will not delaminate, accumulate glue, or wrinkle due to the filling of the soft molding strips. Simultaneously, the surface and internal quality of the parts meet design requirements.

[0037] This invention provides a low-cost method for improving the radius (R) quality of composite materials, comprising the following steps:

[0038] Step A: As Figure 1 As shown, soft molding strip preparation;

[0039] Step A1: Lay fiber layers 20 on both sides of the R-angle soft mold forming fixture 10;

[0040] Step A2: Next, lay rubber strips 30 on the corners of the R-angle soft mold forming fixture 10, and make the rubber strips 30 overlap with the fiber layers 20 on both sides.

[0041] Step A3: After the tiling is completed, seal and cure it. After curing and demolding, grind and shape it into a soft mold strip of 100mm.

[0042] Step B: As Figure 2 As shown, the soft molding strip is laid in 100mm diameter.

[0043] Step B1: Lay the prepreg 1 of the part onto the R-angle female mold fixture;

[0044] Step B2: Next, place the isolation material 2 inside the corner of the prepreg 1R, and then place the soft molding strip 100 on top of the isolation material 2 at the corner of the prepreg 1.

[0045] Step B3: Then vacuum bag the parts in the order of breathable felt 3 and vacuum bag 4;

[0046] Step B4: After sealing, place the vacuum nozzle and evacuate to ensure that the insulating material 2, soft molding strip 100, breathable felt 3 and vacuum bag 4 are tightly attached to the part;

[0047] Step C: Curing. Check for vacuum leaks. Once the requirements are met, transfer the product to an autoclave for curing.

[0048] Step D: Demold and remove the part after curing.

[0049] Specifically, the fiber layer 20 laid in step A1 is carbon fiber or glass fiber; further, the specific steps are to pre-brush three coats of release agent or lay release cloth on the R-corner soft mold forming fixture 10, and then lay a layer of carbon fiber or glass fiber, the range of which is 5mm outward from the R-corner area.

[0050] Furthermore, the rubber strip 30 used in step A2 is an Airpad (cushioning air cushion) rubber strip, and the range of the Airpad rubber strip is 3mm outward from the R-corner area.

[0051] Specifically, in step A3, the curing pressure is 600 kPa to 650 kPa, the curing temperature is 175 ± 5℃, and the curing time is not less than 120 min. After curing, the temperature drops below 60℃ before the soft molding strip 100 is taken out of the autoclave. When the pressure reaches 140 kPa during the curing process, the vacuum bag is connected to the atmosphere and kept connected until the curing is completed.

[0052] When demolding the soft molding strip 100, carefully remove it using a wooden or plastic wedge. After simple reshaping and inspection, if there are no problems, the soft molding strip 100 is ready for use.

[0053] In this embodiment, after the part is removed, the soft molding strip 100 is checked and found to be without problems and can be reused.

[0054] Compared to traditional R-corner part packaging methods, the method of this invention ensures the R-corner profile of the parts. Furthermore, the conformal pressure transfer of the soft molding strip makes the curing pressure more uniform during R-corner forming, reducing the risk of wrinkling. Simultaneously, heat transfer is more uniform during curing, thus ensuring the internal quality of the parts remains unaffected. Moreover, the method of this invention only requires the addition of a soft molding strip made of Airpad material during packaging, eliminating the need for traditional pressure pads or auxiliary tooling, reducing manufacturing costs and simplifying the manufacturing process. Additionally, the parts are easily demolded after curing, avoiding damage during the demolding process.

[0055] The above description is merely a description of preferred embodiments of the present invention and is not intended to limit the scope of the present invention in any way. Any changes or modifications made by those skilled in the art based on the above disclosure shall fall within the protection scope of the claims.

Claims

1. A low-cost method for improving the radius (R) quality of composite materials, characterized in that, Includes the following steps: Step A: Preparation of soft molding strips; Step A1: Apply fiber layers (20) to both sides of the R-angle soft mold forming fixture (10). Step A2: Then, a rubber strip (30) is laid on the corner of the R-angle soft mold forming fixture (10), and the rubber strip (30) overlaps with the fiber layers (20) on both sides; Step A3: After the tiling is completed, seal and cure it. After curing and demolding, grind and shape it into a soft mold strip (100). Step B: Lay the soft molding strip (100); Step B1: Lay the prepreg (1) of the part on the R-angle female mold fixture; Step B2: Next, place the isolation material (2) inside the R-corner of the prepreg (1), and then place the soft molding strip (100) on top of the isolation material (2) at the corner of the prepreg (1); Step B3: Then vacuum bag the parts in the order of breathable felt (3) and vacuum bag (4); Step B4: After sealing, place the vacuum nozzle and evacuate to ensure that the insulating material (2), soft molding strip (100), breathable felt (3) and vacuum bag (4) are tightly attached to the part; Step C: Curing. Check for vacuum leaks. Once the requirements are met, transfer the product to an autoclave for curing. Step D: Demold and remove the part after curing.

2. The method for improving the R-angle quality of composite materials at low cost as described in claim 1, characterized in that, The fiber layer (20) laid in step A1 is carbon fiber or glass fiber.

3. The method for improving the R-angle quality of composite materials at low cost as described in claim 2, characterized in that, The specific steps of step A1 are as follows: brush three coats of release agent or lay release cloth on the R-corner soft mold forming fixture (10), and then lay a layer of carbon fiber or glass fiber, extending 5mm outward from the R-corner area.

4. The method for improving the R-angle quality of composite materials at low cost as described in claim 1, characterized in that, The rubber strip (30) used in step A2 is an Airpad rubber strip.

5. A low-cost method for improving the R-angle quality of composite materials as described in claim 4, characterized in that, The range of the Airpad rubber strip extends 3mm outward from the R-corner area.

6. The method for improving the R-angle quality of composite materials at low cost as described in claim 1, characterized in that, After removing the part in step D, inspect the soft molding strip (100) and reuse it.

7. A low-cost method for improving the R-angle quality of composite materials as described in claim 1, characterized in that, The curing pressure in step A3 is 600kPa~650kPa, the curing temperature is 175±5℃, and the curing time is not less than 120min. After curing, the temperature drops to below 60℃ and the soft molding strip (100) is taken out of the autoclave. When the pressure reaches 140kPa during the curing process, the vacuum bag is connected to the atmosphere and kept connected until the curing is completed.

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