Pressure equalizing plate and curing method of metal honeycomb sandwich structure

Abstract

The invention belongs to the technical field of composite material maintenance, and particularly relates to a pressure equalizing plate and a curing method of a metal honeycomb sandwich structure. The pressure equalizing plate comprises a honeycomb plate body, the honeycomb plate body is arranged on the face, away from the metal honeycomb sandwich structure, of the skin, and a honeycomb core of the honeycomb plate body is perpendicular to the surface of the skin. An air guide groove penetrating through the surface of the honeycomb plate body is formed in the face, away from the skin, of the honeycomb plate body. According to the pressure equalizing plate, the honeycomb plate body is adopted, it is ensured that enough downward pressure is applied to the skin in the curing process of the metal honeycomb sandwich structure and the skin, meanwhile, gas in the cavity of the metal honeycomb sandwich structure can be guided out, the phenomenon that the gas in the cavity is heated to expand, so that the bonded skin is jacked open, and the hollowing and degumming phenomena are caused is avoided, and the service life of the metal honeycomb sandwich structure is prolonged. And the bonding quality of the metal honeycomb sandwich structure and the skin is greatly improved.

Description

Technical Field

[0001] The present application belongs to the technical field of composite material repair, and specifically relates to a curing method for a pressure equalizing plate and a metal honeycomb sandwich structure. Background Art

[0002] Lightweighting of equipment structures is an eternal theme pursued in the development of civil aviation. Lightweighting of structures can increase payload, increase flight range, and reduce energy consumption. Therefore, in the design and manufacture of civil airliners, a large number of composite materials with metal honeycomb sandwich structures are used to make structural components to achieve the purpose of lightweighting the aircraft structure. Therefore, during the maintenance and repair of aircraft, it is often necessary to repair the damaged surfaces of the composite materials of the metal honeycomb sandwich structure. The conventional process of repairing the metal honeycomb sandwich structure is: bonding the metal honeycomb sandwich structure and the skin; laying the breathable layer and the adhesive layer in sequence; setting up a pressure plate to increase the downforce so that the skin and the metal honeycomb sandwich structure are more tightly bonded; and heating and curing after the vacuum bag is made.

[0003] Metal honeycomb sandwich composites have a unique structure. The honeycomb core is a hollow structure, thus storing a large amount of gas. During curing, the rising internal temperature causes the gas in the cavity to expand. This expanding gas must be discharged, otherwise it will push the skin and the film apart, causing hollowing and debonding between the skin and the metal honeycomb sandwich structure, seriously affecting the bonding quality.

[0004] In the existing technology, the pressure equalizing plates are all solid structures and are not breathable, which makes it difficult for the gas to escape after reaching the pressure equalizing plate layer, thereby generating a huge reverse force, pushing the skin and the film apart and causing hollowing and debonding. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art or related art, namely, the problem that the solid pressure equalizing plate has poor air permeability, which makes it difficult to drain the gas inside the metal honeycomb sandwich structure.

[0006] In view of this, the first aspect of the present invention provides a pressure equalizing plate, which is a honeycomb plate body. While applying sufficient downward pressure on the skin, it can also drain the gas inside the metal honeycomb sandwich structure, greatly improving the bonding quality.

[0007] A second aspect of the present invention provides a method for curing a metal honeycomb sandwich structure, wherein the method uses the above-mentioned pressure equalizing plate during the curing of the metal honeycomb sandwich structure and the skin.

[0008] The specific technical solutions include the following:

[0009] According to a first aspect of an embodiment of the present application, a pressure equalizing plate is provided, comprising a honeycomb panel body; the honeycomb panel body is arranged on a side of the skin away from the metal honeycomb sandwich structure, and the honeycomb core of the honeycomb panel body is perpendicular to the surface of the skin; an air guide groove is provided on the side of the honeycomb panel body away from the skin, which passes through the surface of the honeycomb panel body.

[0010] Furthermore, there are multiple air guide grooves.

[0011] Furthermore, the air guide groove passes through the center point of the honeycomb panel body.

[0012] Furthermore, the thickness of the honeycomb panel is greater than 5 mm and less than 25 mm.

[0013] Preferably, the cross section of the air guide groove is V-shaped; the opening width of the air guide groove is 3 mm-5 mm, and the height of the air guide groove is 0.2-0.4 times the thickness of the honeycomb panel body.

[0014] Preferably, the cross section of the air guide groove is semicircular; the radius of the air guide groove is 0.2-0.3 times the thickness of the honeycomb panel.

[0015] According to the second aspect of an embodiment of the present application, a method for curing a metal honeycomb sandwich structure is provided. During the curing of the metal honeycomb sandwich structure and the skin, a pressure equalizing plate as described in any of the above technical solutions is used. The method includes: bonding the metal honeycomb sandwich structure and the skin; arranging the honeycomb panel body on the skin; packaging a vacuum bag on the outside of the metal honeycomb sandwich structure and the honeycomb panel body, and evacuating the bag; and heating and curing.

[0016] Furthermore, after the step of bonding the metal honeycomb sandwich structure and the skin, the method further includes: laying a first breathable layer, a glue-absorbing layer and a second breathable layer on the skin in sequence; the step of arranging the honeycomb panel body on the skin includes arranging the honeycomb panel body on the second breathable layer.

[0017] Furthermore, after the step of arranging the honeycomb panel body on the skin, the method also includes: laying a third breathable layer on the side of the honeycomb panel body away from the skin; the step of packaging the vacuum bag outside the metal honeycomb sandwich structure and the honeycomb panel body includes packaging the vacuum bag outside the metal honeycomb sandwich structure and the third breathable layer.

[0018] Furthermore, during the heating and curing step, vacuum is continuously drawn.

[0019] Compared with the prior art, the present invention has at least the following beneficial effects:

[0020] The pressure equalizing plate of the present application adopts a honeycomb panel body, which ensures that sufficient downward pressure is applied to the skin during the curing process of the metal honeycomb sandwich structure and the skin, while also being able to discharge the gas inside the cavity of the metal honeycomb sandwich structure, thereby avoiding the gas inside the cavity from expanding due to heat and pushing open the bonded skin, causing hollowing and debonding, and greatly improving the bonding quality of the metal honeycomb sandwich structure and the skin. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Various other advantages and benefits will become apparent to those skilled in the art by reading the detailed description of the preferred embodiment below. The accompanying drawings are only for the purpose of illustrating the preferred embodiment and are not to be considered as limiting the present application. In the accompanying drawings:

[0022] Figure 1 This is a cross-sectional schematic diagram of the component structure of the curing system according to an embodiment of the present application;

[0023] Figure 2 Schematic cross-sectional view of a pressure equalizing plate according to an embodiment of the present application;

[0024] Figure 3 A top view of a pressure equalizing plate according to an embodiment of the present application;

[0025] Figure 4 This is a schematic diagram of the airflow direction of an embodiment of the present application.

[0026] The reference numerals indicate:

[0027] 1-honeycomb panel; 11-air guide groove; 12-honeycomb core; 2-metal honeycomb sandwich structure; 3-skin; 4-vacuum bag; 51-first breathable layer; 52-glue absorption layer; 53-second breathable layer; 54-third breathable layer. DETAILED DESCRIPTION

[0028] In order to better understand the above technical solution, the technical solution of the embodiment of the present application is described in detail below through the accompanying drawings and specific embodiments. It should be understood that the embodiment of the present application and the specific features in the embodiment are detailed descriptions of the technical solution of the embodiment of the present application, rather than limitations on the technical solution of the present application. In the absence of conflict, the embodiment of the present application and the technical features in the embodiment can be combined with each other.

[0029] In view of this, according to a first aspect of an embodiment of the present application, a pressure equalizing plate is provided, such as Figure 2 、 Figure 3 As shown, it includes a honeycomb panel body 1; the honeycomb panel body 1 is arranged on the side of the skin 3 away from the metal honeycomb sandwich structure 2, and the honeycomb core 12 of the honeycomb panel body 1 is perpendicular to the surface of the skin 3; an air guide groove 11 is provided on the side of the honeycomb panel body 1 away from the skin 3, which passes through the surface of the honeycomb panel body 1.

[0030] Specifically, when the gas inside the metal honeycomb sandwich structure 2 is heated to expand, the gas escapes from the surface of the skin 3. Figure 4 As shown, the escaping gas rises from the bottom of the honeycomb panel 1 to the top of the panel 1 along direction A through the honeycomb core 12, and is then directed into the external space along direction B along the gas guide grooves 11. In other words, the honeycomb core 12 and the gas guide grooves 11 form a gas guide path that completely guides the gas escaping from the metal honeycomb sandwich structure 2, thereby preventing gas accumulation within the metal honeycomb sandwich structure 2, which can cause hollowing and affect bonding quality.

[0031] Furthermore, in one embodiment, there are multiple air guide grooves 11.

[0032] Furthermore, in one embodiment, Figure 3 As shown, the air guide groove 11 passes through the center point of the honeycomb panel body 1.

[0033] Specifically, since the honeycomb panel 1 has high edge pressure and low center pressure, gas will gather at the center during the curing process. Therefore, the gas guide groove 11 passes through the center of the honeycomb panel 1 and extends to the edges of the honeycomb panel 1 at both ends, which is more conducive to the discharge of gas.

[0034] Furthermore, in one embodiment, the thickness of the honeycomb panel 1 is greater than 5 mm and less than 25 mm.

[0035] Specifically, the function of the pressure equalizing plate is to convert the external air pressure into downward pressure on the skin 3 under vacuum. When the pressure equalizing plate is set to the honeycomb panel body 1, in order to facilitate the transmission of the downward pressure along the shape of the bonding area, the thickness of the honeycomb panel body cannot be too large. Excessive thickness will affect the transmission of the downward pressure and thus affect the bonding effect. At the same time, since the air guide groove 11 needs to be cut on the honeycomb panel body 1, too small a thickness will result in insufficient strength of the honeycomb panel body 1 after cutting the air guide groove 11, and the pressure equalizing effect will not be achieved. This solution has obtained the optimal thickness range of the honeycomb panel body 1 through repeated experiments, but it should be noted that the thickness size of the honeycomb panel body 1 is not a limitation on the scope of protection of this application.

[0036] Preferably, in a specific embodiment, the cross section of the air guide groove 11 is V-shaped; the opening width of the air guide groove 11 is 3 mm-5 mm, and the height of the air guide groove 11 is 0.2-0.4 times the thickness of the honeycomb panel body 1 .

[0037] Preferably, in a specific embodiment, the cross section of the air guide groove 11 is semicircular; the radius of the air guide groove 11 is 0.2-0.3 times the thickness of the honeycomb panel body 1 .

[0038] Specifically, since the entire curing system components are arranged in a vacuum bag 4 during curing, if there are structures such as sharp corners, the vacuum bag 4 is easily punctured, and after leakage, the metal honeycomb sandwich structure 2 and the skin 3 cannot be pressurized to achieve the curing effect; at the same time, since the pressure in the vacuum bag 4 is relatively high, structures such as sharp corners are easily damaged and collapsed by the pressure, resulting in the damage of the honeycomb panel 1 and a reduction in service life, thereby increasing maintenance costs. Therefore, this solution sets the cross-section of the air guide groove 11 to a V-shaped or semicircular shape without sharp corners, and after many experiments, the optimal slot size is obtained, which can not only ensure the bonding quality but also take into account the durability of the honeycomb panel 1. It should be noted that the shape and size of the cross-section of the air guide groove 11 are not limitations on the scope of protection of this application. Any shape and size of the air guide groove that can achieve the air guide function is within the scope of protection of this application.

[0039] According to the second aspect of the embodiment of the present application, a method for curing a metal honeycomb sandwich structure is provided. During the curing of the metal honeycomb sandwich structure and the skin, a pressure equalizing plate as described in any of the above technical solutions is used. The method includes: bonding the metal honeycomb sandwich structure 2 and the skin 3; arranging the honeycomb panel body 1 on the skin 3; packaging a vacuum bag 4 on the outside of the metal honeycomb sandwich structure 2 and the honeycomb panel body 1, and evacuating the bag; and heating and curing.

[0040] Furthermore, in one embodiment, after the step of bonding the metal honeycomb sandwich structure 2 and the skin 3, the method further includes: laying a first breathable layer 51, a glue-absorbing layer 52 and a second breathable layer 53 in sequence on the skin 3; the step of arranging the honeycomb panel body 1 on the skin 3 includes arranging the honeycomb panel body 1 on the second breathable layer 53.

[0041] Furthermore, in one embodiment, after the step of setting the honeycomb panel body 1 on the skin 3, the method also includes: laying a third breathable layer 54 on the side of the honeycomb panel body 1 away from the skin 3; the step of packaging the vacuum bag 4 outside the metal honeycomb sandwich structure 2 and the honeycomb panel body 1 includes packaging the vacuum bag 4 outside the metal honeycomb sandwich structure 2 and the third breathable layer 54.

[0042] Furthermore, in one embodiment, vacuum is continuously applied during the heating and curing step.

[0043] Specifically, the structure of the overall curing system components is as follows Figure 1As shown. When bonding the metal honeycomb sandwich structure 2 and the skin 3, excess glue will overflow, so the glue-absorbing layer 52 is used to absorb the overflowed glue; the first breathable layer 51 and the second breathable layer 53 respectively isolate the glue-absorbing layer 52 from the skin 3 and the honeycomb panel body 1. The third breathable layer 54 prevents the honeycomb panel body 1 from direct contact with the vacuum bag 4, thereby preventing the vacuum bag 4 from rupturing and protecting the honeycomb panel body 1 from damage. The first breathable layer 51, the glue-absorbing layer 52, the second breathable layer 53 and the third breathable layer 54 are all made of porous and loose materials and will not hinder the escape of gas.

[0044] This curing method has all the beneficial effects of the pressure equalizing plate of the above technical solution, which will not be described in detail here.

[0045] Throughout this specification, terms such as "one embodiment," "some embodiments," and "specific embodiments" mean that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0046] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A pressure equalizing plate, characterized in that: It comprises a honeycomb panel body (1); The honeycomb panel body (1) is arranged on a side of the skin (3) away from the metal honeycomb sandwich structure (2), and the honeycomb core (12) of the honeycomb panel body (1) is perpendicular to the surface of the skin (3); An air guide groove (11) penetrating the surface of the honeycomb panel (1) is provided on a surface of the honeycomb panel (1) away from the skin (3).

2. The pressure equalizing plate according to claim 1, characterized in that: There are multiple air guide grooves (11).

3. The pressure equalizing plate according to claim 1, characterized in that: The air guide groove (11) passes through the center point of the honeycomb panel body (1).

4. The pressure equalizing plate according to claim 1, characterized in that: The thickness of the honeycomb panel (1) is greater than 5 mm and less than 25 mm.

5. The pressure equalizing plate according to claim 1, characterized in that: The cross section of the air guide groove (11) is V-shaped; The opening width of the air guide groove (11) is 3 mm to 5 mm, and the height of the air guide groove (11) is 0.2 to 0.4 times the thickness of the honeycomb plate body (1).

6. The pressure equalizing plate according to claim 1, characterized in that: The cross section of the air guide groove (11) is semicircular; The radius of the air guide groove (11) is 0.2-0.3 times the thickness of the honeycomb plate body (1).

7. A method for curing a metal honeycomb sandwich structure, characterized in that: During the curing process of the metal honeycomb sandwich structure and the skin, the pressure equalizing plate according to any one of claims 1 to 6 is used, and the method comprises: Bonding the metal honeycomb sandwich structure (2) and the skin (3); Arranging the honeycomb panel body (1) on the skin (3); A vacuum bag (4) is packaged outside the metal honeycomb sandwich structure (2) and the honeycomb panel (1), and vacuum is drawn; Heat curing.

8. The curing method of the metal honeycomb sandwich structure according to claim 7, characterized in that: After the step of bonding the metal honeycomb sandwich structure (2) and the skin (3), the method further comprises: laying a first air permeable layer (51), a glue absorbing layer (52), and a second air permeable layer (53) in sequence on the skin (3); The step of arranging the honeycomb panel body (1) on the skin (3) includes arranging the honeycomb panel body (1) on the second air permeable layer (53).

9. The curing method of the metal honeycomb sandwich structure according to claim 7, characterized in that: After the step of arranging the honeycomb panel body (1) on the skin (3), the method further comprises: laying a third air permeable layer (54) on a surface of the honeycomb panel body (1) away from the skin (3); The step of packaging the vacuum bag (4) outside the metal honeycomb sandwich structure (2) and the honeycomb panel body (1) includes packaging the vacuum bag (4) outside the metal honeycomb sandwich structure (2) and the third air permeable layer (54).

10. The curing method of the metal honeycomb sandwich structure according to claim 7, characterized in that: During the heat curing step, vacuum is continuously applied.

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