Cut-off end cushion of cap-shaped stiffened wall plate and forming method

Abstract

The invention provides a cut-off end buffer pad of a cap-shaped stiffened wall plate and a forming method of the cut-off end buffer pad. The buffer pad comprises an elastic buffer layer, a rigid supporting layer and an isolating layer. According to the co-glued cap type stiffened wallboard, the elastic buffer layer in the shape of the polygonal frustum is arranged, so that the pressure generated after the tubular vacuum bag is vacuumized is uniformly, smoothly and progressively transmitted to the skin, the problem that the skin at the end of the cap type stringer is wrinkled is effectively solved, and the forming quality of the co-glued cap type stiffened wallboard is improved. Through the arrangement of the rigid supporting layer, rigid supporting and pressure conduction are provided. Through the arrangement of the isolation layer, the contact area with the skin is increased, stress is diffused, indentation is further avoided, meanwhile, the elastic buffer layer can be isolated from the skin, and direct contact between the elastic buffer layer and the skin is avoided. The method is easy and convenient to operate, the production efficiency of the co-glued cap type stiffened wall plate can be remarkably improved, and application and popularization are facilitated.

Description

Technical Field

[0001] This application relates to the field of aerospace composite materials technology, and more specifically, to a stop-end buffer pad for a hat-shaped stiffened panel and a molding method thereof. Background Technology

[0002] In the field of aerospace composite material parts, fuselage panels, as core load-bearing components, directly determine the structural strength, lightweight level, and flight safety of aerospace equipment through their structural rationality and manufacturing precision. Among them, cap-shaped stiffened panels have become the mainstream structural form of fuselage panels due to their excellent buckling resistance and load-bearing efficiency. Cap-shaped stiffened panels are formed by integrating cap-shaped stringers with the skin.

[0003] Currently, the mainstream manufacturing process for cap-shaped stiffened panels is the co-bonding autoclave molding process. This process achieves a reliable connection between the cap-shaped stringer and the skin through one-time molding, combining advantages in molding efficiency and connection quality. During the co-bonding molding process, to achieve uniform pressure on the inner cavity of the cap-shaped stringer and ensure the quality of the stringer molding, the industry commonly uses tubular vacuum bags. The expansion force of the inflated tubular vacuum bag creates stable pressure on the inner cavity of the stringer.

[0004] However, the above-mentioned molding process has key technical defects in practical applications: after the tubular vacuum bag is finally manufactured, uneven pressure distribution is prone to occur in its edge area. This uneven pressure will directly act on the skin surface of the cap-shaped stringer end, causing indentations on the skin. Furthermore, during the autoclave curing process, the tubular vacuum bag continuously applies non-uniform pressure to the stringer end skin. If the degree of pressure unevenness exceeds the threshold, it will cause wrinkling defects in the stringer end skin. Since the fuselage panels have extremely high requirements for surface flatness and structural integrity, once such defects exceed the engineering allowable range, it will directly lead to the scrapping of the entire part, significantly increasing production costs and reducing production efficiency.

[0005] To address the aforementioned issues, existing technologies employ a method of placing a gasket between the stringer end skin and the tubular vacuum bag. The gasket's buffering effect reduces the uneven pressure exerted by the tubular vacuum bag on the skin, thereby suppressing defects. Currently, commonly used gasket materials in production mainly include three types: thin metal gaskets, thin composite gaskets, and laminated breathable felt. However, all have significant technical shortcomings: while metal gaskets possess some buffering capacity, they are prone to plastic deformation during molding, making them unreusable and leading to material waste and increased processing costs; composite gaskets have excessive rigidity, and while buffering pressure, their edges can easily cause severe indentations on the skin, exacerbating the risk of localized defects; laminated breathable felt gaskets are typically wrapped with an isolation film, and the wrapped structure is prone to positional slippage during molding, leading to uneven pressure redistribution at the stringer end and subsequently causing skin wrinkles; furthermore, laminated breathable felt easily forms uneven wrinkles during vacuuming, which can directly imprint on the skin surface, causing skin depression defects.

[0006] In summary, there is a need to provide an improved technical solution that addresses the shortcomings of the existing technology. Summary of the Invention

[0007] The purpose of this application is to provide a stop-end buffer pad and molding method for a hat-shaped reinforced wall panel, which can disperse the pressure during bag making and curing processes without affecting the skin, thereby improving the molding quality and production qualification rate of the hat-shaped reinforced wall panel.

[0008] In a first aspect, this application provides a stop-end buffer pad for a hat-shaped reinforced wall panel, comprising:

[0009] The elastic buffer layer is a multi-faceted frustum shape, including a top surface, a bottom surface, and multiple side surfaces located on the sides. The area of ​​the top surface is smaller than the area of ​​the bottom surface, and the multiple side surfaces are arranged at an angle.

[0010] A rigid support layer is disposed on the top surface of the elastic buffer and is attached to the top surface for connection with the tubular vacuum bag;

[0011] An isolation layer is disposed on the bottom surface of the elastic buffer and is attached to the bottom surface for contact with the skin.

[0012] In one feasible embodiment, the elastic buffer layer is made of an elastic material with a hardness of 50-70 HA.

[0013] In one feasible embodiment, the thickness of the elastic buffer layer is 0.5-1.5 mm.

[0014] In one feasible approach, the area of ​​the isolation layer is larger than the bottom surface area of ​​the elastic buffer layer.

[0015] In one feasible approach, the insulating layer is made of a breathable material.

[0016] In one feasible approach, the rigid support layer is made of a lightweight rigid material.

[0017] In one feasible embodiment, the rigid support layer is aramid paper, and the thickness of the rigid support layer is 0.05-0.5 mm.

[0018] In one feasible embodiment, the side tilt angle of the elastic buffer layer is 15-45°.

[0019] According to a second aspect of this application, a method for forming a hat-shaped stiffened wall panel is also provided, comprising the following steps:

[0020] S1, Assembly of cap-shaped stringers and skin;

[0021] S2. A tubular vacuum bag is installed in the groove of the hat-shaped stringer;

[0022] S3. Insert a stop end buffer pad of the hat-shaped stiffened wall panel as described in any one of claims 1 to 8 below the tubular vacuum bag at the end of the hat-shaped stringer.

[0023] S4. After sealing the tubular vacuum bag together with the outer vacuum bag, the vacuum is removed so that the assembly surface of the cap-shaped stringer and the skin is bonded together under force.

[0024] S5. After the cap-shaped stringer and skin are solidified and connected, remove the gaskets and tubular vacuum bags to complete the forming of the cap-shaped reinforced wall panel.

[0025] Compared with the prior art, the beneficial effects of this application are as follows:

[0026] In this application's technical solution, a multi-faceted, frustum-shaped elastic buffer layer is used to uniformly and smoothly transfer the pressure generated after vacuuming the tubular vacuum bag to the skin, effectively solving the problem of wrinkling defects at the end of the cap-shaped stringer skin and improving the molding quality of the co-bonded cap-shaped stiffened wall panel. A rigid support layer provides rigid support and pressure transmission. An isolation layer increases the contact area with the skin, diffusing stress and further preventing indentations. It also isolates the elastic buffer layer from the skin, preventing direct contact. This application is simple to operate, significantly improves the production efficiency of co-bonded cap-shaped stiffened wall panels, and is conducive to widespread use. Attached Figure Description

[0027] Figure 1 This is a structural schematic diagram of the end buffer pad of the cap-shaped reinforced wall panel in use according to an embodiment of the present invention.

[0028] Figure 2This is a cross-sectional view of the stop end buffer pad of the hat-shaped reinforced wall panel according to an embodiment of the present invention.

[0029] Figure 3 This is a flowchart of the forming method of the hat-shaped stiffened wall panel according to an embodiment of the present invention.

[0030] The reference numerals in the attached figures are explained as follows:

[0031] 1. Hat-shaped stringer; 2. Skin; 3. Tubular vacuum bag; 4. Cut-off end buffer pad; 41. Elastic buffer layer; 42. Rigid support layer; 43. Isolation layer. Detailed Implementation

[0032] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. These embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0033] In the description of this invention, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for 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 the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[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 can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0035] Furthermore, in the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0036] According to the first aspect of this application, see Figure 1 and Figure 2 Firstly, a stop-end buffer pad for a hat-shaped reinforced wall panel is provided, comprising:

[0037] The elastic buffer layer 41 is a frustum shape, including a top surface, a bottom surface, and multiple side surfaces on the sides. The area of ​​the top surface is smaller than the area of ​​the bottom surface, and the multiple side surfaces are inclined. By making the elastic buffer layer 41 into a frustum shape, the peripheral thickness of the elastic buffer layer 41 is less than the thickness of the middle part of the elastic buffer layer 41.

[0038] By setting the elastic buffer layer 41 to a frustum shape, with the area increasing sequentially from the top to the bottom, the stress-bearing area between the present application and the skin 2 can be increased, so that the stress acting on the skin 2 is more uniform and wrinkles are avoided due to variations. The frustum shape also reduces the thickness of the edge of the elastic buffer layer 41, preventing indentations from appearing on the skin 2.

[0039] A rigid support layer 42 is disposed on the top surface of the elastic buffer and is attached to the top surface; the rigid support layer 42 is used to connect with the tubular vacuum bag 3, and after the tubular vacuum bag 3 is evacuated, the pressure generated is evenly transmitted to the elastic buffer layer 41.

[0040] An isolation layer 43 is disposed on the bottom surface of the elastic buffer and is attached to the bottom surface; it is used to contact the skin 2 to isolate the elastic buffer layer 41 from the skin 2 and prevent the elastic buffer layer 41 from directly contacting the skin 2.

[0041] It should be noted that the initial state of the elastic buffer layer 41 is a semi-vulcanized state, so the rigid support layer 42 and the isolation layer 43 can be bonded and fixed. When the skin 2 and the stringer are heated and pressurized for curing, the elastic buffer layer 41 deforms and flows, and the elastic buffer layer 41 is connected and fixed with the rigid support layer 42 and the isolation layer 43, ensuring that the application does not separate during use.

[0042] In one feasible embodiment, the elastic buffer layer 41 has a hardness of 50-70HA, which can ensure support while also absorbing and buffering stress.

[0043] In one feasible embodiment, the thickness of the elastic buffer layer 41 is 0.5-1.5 mm. This ensures support while preventing indentations on the skin 2.

[0044] In one feasible embodiment, the area of ​​the isolation layer 43 is larger than the bottom surface area of ​​the elastic buffer layer 41. By providing the isolation layer 43, the contact area with the skin 2 can be increased, stress can be diffused, and indentation can be further avoided.

[0045] In one feasible embodiment, the isolation layer 43 is a breathable material, which prevents residual gas between the isolation layer 43 and the skin 2 during vacuum pressurization, ensuring that all residual gas can be extracted and maintaining the flatness of the skin 2.

[0046] Specifically, in this embodiment, the isolation layer 43 is a single-sided adhesive polytetrafluoroethylene film with a thickness of 0.05 mm. This ensures adhesion to the bottom surface of the elastic buffer layer 41 while maintaining breathability.

[0047] In one feasible approach, the rigid support layer 42 is made of a lightweight rigid material to provide rigid support and pressure transmission.

[0048] Specifically, in this embodiment, the rigid support layer 42 is aramid paper with a thickness of 0.05-0.5 mm. Considering the influence of thickness on airflow and thermal conductivity, the aramid paper is selected and its thickness is set to avoid deformation and softening of the rigid support layer 42 at the curing temperature.

[0049] In one feasible embodiment, the side tilt angle of the elastic buffer layer 41 is 15-45°.

[0050] It should be noted that by controlling the tilt angle of the side, the gradient change rate of the side of the elastic buffer layer 41 is 0.5-1.2 mm / cm, that is, for every 1 cm increase in thickness, the side length of the elastic buffer layer 41 decreases by 1-2.4 mm.

[0051] According to the second aspect of this application, such as Figure 1 and Figure 3 As shown, a method for forming a hat-shaped stiffened wall panel is also provided, including the following steps:

[0052] S1. Assemble the hat-shaped stringer 1 and the skin 2.

[0053] In step S1, the axis and hole positions of the hat-shaped stringer 1 are aligned with the marking lines of the skin 2 before pre-fixing.

[0054] It should be noted that temporary clamps can be used to pre-fix the cap-shaped stringer 1 and the skin 2 to prevent displacement.

[0055] In step S1, the method further includes: uniformly applying adhesive to the mating surfaces of the cap-shaped stringer 1 and the skin 2, wherein the thickness of the adhesive is 0.12-1mm.

[0056] S2. A tubular vacuum bag 3 is installed in the groove of the hat-shaped stringer 1.

[0057] S3. Insert the end buffer pad 4 of the cap-shaped stiffened wall panel provided in the first aspect below the tubular vacuum bag 3 at the end of the cap-shaped stringer 1. By tightly attaching the buffer pad to the bonding surface, support is provided for the tubular vacuum bag outside the end of the cap-shaped stringer 1, and it is ensured that there is no gap between the edge of the buffer pad and the end of the stringer.

[0058] It should be noted that step S3 includes at least setting an air extraction nozzle on the tubular vacuum bag 3, and the air extraction nozzle is connected to the vacuum equipment through a pipeline.

[0059] S4. After sealing the tubular vacuum bag 3 together with the outer vacuum bag, the vacuum is removed so that the cap-shaped stringer 1 and the skin 2 are bonded together under force.

[0060] Specifically, in step S4, the tubular vacuum bag 3 and the inside of the outer vacuum bag are evacuated by the autoclave vacuum system. After confirming that there is no leakage, the autoclave equipment is used to heat and pressurize. After the tubular vacuum bag 3 shrinks under vacuum, it forms uniform pressure on the assembly surface.

[0061] S5. After the hat-shaped stringer 1 and the skin 2 are solidified and connected, remove the gasket and the tubular vacuum bag 3 to complete the forming of the hat-shaped reinforced wall panel.

[0062] In summary, this application, by setting a multi-faceted elastic buffer layer 41, transmits the pressure generated after vacuuming the tubular vacuum bag 3 to the skin 2 in a uniform and smooth manner, effectively solving the problem of wrinkling defects in the cap-shaped stringer end skin 2 and improving the molding quality of the co-bonded cap-shaped stiffened wall panel. The rigid support layer 42 provides rigid support and pressure transmission. The isolation layer 43 increases the contact area with the skin 2, diffuses stress, further avoids indentation, and also isolates the elastic buffer layer 41 from the skin 2, preventing direct contact. This application is simple to operate, can significantly improve the production efficiency of co-bonded cap-shaped stiffened wall panels, and is conducive to widespread use.

[0063] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and substitutions can be made without departing from the technical principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention.

Claims

1. A buffer pad at the cut-off end of a hat-shaped reinforced wall panel, characterized in that, include: The elastic buffer layer is a multi-faceted frustum shape, including a top surface, a bottom surface, and multiple side surfaces located on the sides. The area of ​​the top surface is smaller than the area of ​​the bottom surface, and the multiple side surfaces are arranged at an angle. A rigid support layer is disposed on the top surface of the elastic buffer and is attached to the top surface for connection with the tubular vacuum bag; An isolation layer is disposed on the bottom surface of the elastic buffer and is attached to the bottom surface for contact with the skin.

2. The end buffer pad of the cap-shaped reinforced wall panel according to claim 1, characterized in that, The elastic buffer layer is made of an elastic material with a hardness of 50-70HA.

3. The end buffer pad of the cap-shaped reinforced wall panel according to claim 1, characterized in that, The thickness of the elastic buffer layer is 0.5-1.5 mm.

4. The end buffer pad of the cap-shaped reinforced wall panel according to claim 1, characterized in that, The area of ​​the isolation layer is larger than the bottom area of ​​the elastic buffer layer.

5. The end buffer pad of the cap-shaped reinforced wall panel according to claim 4, characterized in that, The isolation layer is made of breathable material.

6. The end buffer pad of the cap-shaped reinforced wall panel according to claim 1, characterized in that, The rigid support layer is made of a lightweight rigid material.

7. The end buffer pad of the cap-shaped reinforced wall panel according to claim 6, characterized in that, The rigid support layer is aramid paper, and the thickness of the rigid support layer is 0.05-0.5mm.

8. The end buffer pad of the cap-shaped reinforced wall panel according to claim 1, characterized in that, The side tilt angle of the elastic buffer layer is 15-45°.

9. A method for forming a hat-shaped reinforced wall panel, characterized in that, Includes the following steps: S1, Assembly of cap-shaped stringers and skin; S2. A tubular vacuum bag is installed in the groove of the hat-shaped stringer; S3. Insert a stop end buffer pad of the hat-shaped stiffened wall panel as described in any one of claims 1 to 8 below the tubular vacuum bag at the end of the hat-shaped stringer. S4. After sealing the tubular vacuum bag together with the outer vacuum bag, the vacuum is removed so that the assembly surface of the cap-shaped stringer and the skin is bonded together under force. S5. After the cap-shaped stringer and skin are solidified and connected, remove the gaskets and tubular vacuum bags to complete the forming of the cap-shaped reinforced wall panel.

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