A method for measuring the compression of honeycomb cores before and after curing

Abstract

The present application relates to the technical field of sandwich composite material manufacturing, and particularly discloses a method for measuring compression amount of honeycomb core before and after curing, which comprises the following steps: selecting the type and thickness of the honeycomb core, sequentially laying flexible metal sheets, upper adhesive film, the honeycomb core, lower adhesive film and lower flexible metal sheets on a flat tooling to form a sandwich assembly, measuring the thickness H1 of the sandwich assembly before curing, surrounding the sandwich assembly with a protection assembly to form a curing product, curing the curing product, measuring the thickness H2 of the sandwich assembly after curing, and finally calculating the compression amount S of the sandwich assembly before and after curing, S=H1-H2. The upper and lower flexible metal sheets can effectively fit the deformation amount of the cured honeycomb core, and the thickness of the upper and lower flexible metal sheets does not change before and after curing, thereby effectively improving the accuracy of the measurement.

Description

Technical Field

[0001] This invention relates to the field of sandwich composite material manufacturing technology, and in particular to a method for measuring the compression of a honeycomb core before and after curing. Background Technology

[0002] Currently, sandwich composite materials are widely used in the aerospace field due to their superior performance. These materials typically consist of an upper panel, a honeycomb core, an adhesive film, and a lower panel. During aircraft design, functional requirements and cost control necessitate sandwich structures with different levels of honeycomb cores, such as honeycomb and foam honeycomb cores, or honeycomb with different densities. Because different types of honeycomb cores have different mechanical properties, a step difference appears at the honeycomb core joints after the panels are laid and cured. Current methods for measuring this step difference typically involve laying and curing multiple honeycomb cores with panels, then measuring the thickness of the cured honeycomb cores and panels to obtain the compression amount of different honeycomb cores after curing. However, this method results in panel shrinkage after curing, uneven surfaces, significant errors in thickness measurement, and large data dispersion. Summary of the Invention

[0003] The purpose of this invention is to provide a method for measuring the compression of a honeycomb core before and after curing, so as to solve the problem of inaccurate measurement methods of the compression of a honeycomb core before and after curing in the prior art, and to provide data support for the design and material selection of different core material splicing structures.

[0004] To address the above problems, the present invention provides a method for measuring the compression of a honeycomb core before and after curing, the method comprising:

[0005] S1: Select the type and thickness of the honeycomb core;

[0006] S2: Lay the flexible metal sheet, the upper adhesive film, the honeycomb core, the lower adhesive film, and the lower flexible metal sheet in sequence to form a sandwich assembly, and measure the thickness H1 of the sandwich assembly before curing;

[0007] S3: Using protective components to surround the sandwich assembly to form the part to be cured;

[0008] S4: Curing the part to be cured and measuring the thickness H2 of the sandwich assembly after curing;

[0009] S5: Calculate the compression S of the sandwich assembly before and after curing, S = H1 - H2.

[0010] As an optional technical solution for measuring the compression amount of a honeycomb core before and after curing, both the upper flexible metal sheet and the lower flexible metal sheet are thin aluminum sheets or thin copper sheets.

[0011] As an optional technical solution for measuring the compression amount of a honeycomb core before and after curing, the thickness of both the upper flexible metal sheet and the lower flexible metal sheet is 1.5mm-2.5mm.

[0012] As an optional technical solution for measuring the compression of a honeycomb core before and after curing, S2 also includes:

[0013] Depending on the thickness of the adhesive film, the upper side of the honeycomb core may be bonded to the upper flexible metal sheet via the adhesive film or not; and / or,

[0014] Depending on the thickness of the lower adhesive film, the lower side of the honeycomb core may be bonded to the lower flexible metal sheet via the lower adhesive film or not.

[0015] As an optional technical solution for measuring the compression amount of a honeycomb core before and after curing, the protective component includes a protective strip and a protective baffle. The protective strip is arranged around the sandwich assembly along the height direction of the sandwich assembly, and the protective baffle is disposed on the upper end face of the protective strip and the upper flexible metal sheet.

[0016] After the protective strip is installed around the sandwich assembly, a gap is left between the protective strip and the honeycomb core.

[0017] As an optional technical solution for measuring the compression of the honeycomb core before and after curing, the gap between the protective strip and the honeycomb core is 1mm-2mm.

[0018] As an optional technical solution for measuring the compression amount of a honeycomb core before and after curing, the protective strip is made of aluminum alloy or stainless steel, and the protective baffle is made of glass fiber or carbon fiber.

[0019] As an optional technical solution for measuring the compression of a honeycomb core before and after curing, S4 also includes:

[0020] The part to be cured is then encapsulated;

[0021] The encapsulated part to be cured is cured and shaped according to the curing curve of the autoclave prepreg.

[0022] As an optional technical solution for measuring the compression of a honeycomb core before and after curing, encapsulating the part to be cured includes:

[0023] The part to be cured is sealed with a vacuum bag film, and the vacuum bag film is then evacuated.

[0024] As an optional technical solution for measuring the compression of a honeycomb core before and after curing, S4 also includes:

[0025] Remove the protective component of the cured part and measure the thickness H2 of the cured sandwich assembly.

[0026] The beneficial effects of this invention are as follows:

[0027] This invention provides a method for measuring the compression of a honeycomb core before and after curing. The method includes: first, according to the type and thickness of the honeycomb core required for the experiment, then sequentially laying a flexible metal sheet, an upper adhesive film, a honeycomb core, a lower adhesive film, and a lower flexible metal sheet on a flat fixture to form a sandwich assembly; then measuring the thickness H1 of the sandwich assembly before curing; then surrounding the sandwich assembly with a protective component to form a part to be cured; curing the part to be cured; then measuring the thickness H2 of the sandwich assembly after curing; and finally calculating the compression S of the sandwich assembly before and after curing, where S = H1 - H2. The above method, using upper and lower flexible metal sheets, effectively accommodates the deformation of the honeycomb core after curing. Furthermore, the thicknesses of the upper and lower flexible metal sheets remain unchanged before and after curing, significantly improving measurement accuracy and resolving the problem of uneven panel surfaces leading to large measurement errors in existing technologies. Simultaneously, it can simulate the curing state of prepreg and calculate the compression of the honeycomb core during curing. The obtained compression data exhibits low dispersion, avoiding the high cost and long testing cycles associated with various honeycomb splicing combinations, thus guiding the design and material selection of different core material splicing structures. Attached Figure Description

[0028] Figure 1 This is a flowchart of a method for measuring the compression of a honeycomb core before and after curing, as described in an embodiment of the present invention.

[0029] Figure 2 This is a schematic diagram of the structure of the sandwich assembly and protective components after installation in an embodiment of the present invention;

[0030] Figure 3 This is a cross-sectional view of the sandwich assembly and protective components after installation in an embodiment of the present invention;

[0031] Figure 4 This is a side view of the sandwich assembly in an embodiment of the present invention.

[0032] In the picture:

[0033] 1. Honeycomb core;

[0034] 2. Apply flexible metal sheet;

[0035] 3. Apply adhesive film;

[0036] 4. Apply adhesive film;

[0037] 5. Flexible metal sheet;

[0038] 6. Protective components; 61. Protective strips; 62. Protective panels;

[0039] 7. Sandwich assembly;

[0040] 8. Parts to be cured. Detailed Implementation

[0041] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. 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.

[0042] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "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. The terms "first position" and "second position" refer to two different positions. Furthermore, "above," "on top of," and "over" the first feature in relation to the second feature includes the first feature directly above and diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "under," and "below" the first feature in relation to the second feature includes the first feature directly below and diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0043] 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 based on the specific circumstances.

[0044] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0045] like Figures 1 to 4 As shown, this embodiment provides a method for measuring the compression of a honeycomb core before and after curing. The method includes: S1: Selecting the type and thickness of the honeycomb core 1; S2: Sequentially laying on a flexible metal sheet 2, an upper adhesive film 3, the honeycomb core 1, a lower adhesive film 4, and a lower flexible metal sheet 5 to form a sandwich assembly 7, and measuring the thickness H1 of the sandwich assembly 7 before curing; S3: Using a protective component 6 to surround the sandwich assembly 7 to form a part 8 to be cured; S4: Curing the part 8 to be cured, and measuring the thickness H2 of the sandwich assembly 7 after curing; S5: Calculating the compression S of the sandwich assembly 7 before and after curing, where S = H1 - H2.

[0046] Using the above method, an upper flexible metal sheet 2 and a lower flexible metal sheet 5 are used, which can effectively accommodate the deformation of the honeycomb core 1 after curing. Furthermore, the thickness of the upper flexible metal sheet 2 and the lower flexible metal sheet 5 does not change before and after curing, which effectively improves the accuracy of the measurement and solves the problem of uneven panel surface after curing, which leads to large measurement errors in the prior art. At the same time, it can also simulate the curing state of the prepreg and calculate the compression of the honeycomb core 1 during the curing process. The obtained compression data has low dispersion, avoiding the problems of high test costs and long cycles for various honeycomb splicing combinations, so as to guide the design and material selection of different core material splicing structures.

[0047] It should be noted that different types of honeycomb cores can be cured individually or together, depending on the dimensions of the protective component 6 and the honeycomb core 1.

[0048] In this embodiment, both the upper flexible metal sheet 2 and the lower flexible metal sheet 5 are, but are not limited to, thin aluminum sheets or thin copper sheets. The thin aluminum sheets and thin copper sheets have a certain degree of flexibility, enabling them to conform to the deformation of the honeycomb core 1 after curing. Furthermore, the thickness of the thin aluminum sheets or thin copper sheets does not change after curing, thus effectively ensuring the accuracy of the measurement.

[0049] Furthermore, the thickness of both the upper flexible metal sheet 2 and the lower flexible metal sheet 5 is set to 1.5mm-2.5mm. This setting limits the thickness of the upper flexible metal sheet 2 and the lower flexible metal sheet 5 to the aforementioned range, ensuring that both have a certain degree of flexibility and rigidity. The thickness of the upper flexible metal sheet 2 and the lower flexible metal sheet 5 can be selected as 1.5mm, 2mm, or 2.5mm, etc., according to actual needs. In this solution, preferably, the thickness of both the upper flexible metal sheet 2 and the lower flexible metal sheet 5 is 2mm.

[0050] Specifically, S2 also includes: the thickness of the adhesive film 3 can be selected according to actual needs, and then, depending on the thickness of the adhesive film 3, the upper side of the honeycomb core 1 can be bonded to the upper flexible metal sheet 2 through the adhesive film 3 or not bonded.

[0051] Similarly, the thickness of the lower adhesive film 4 can be selected according to actual needs. Then, depending on the thickness of the lower adhesive film 4, it can be selected whether to bond the lower side of the honeycomb core 1 to the lower flexible metal sheet 5 through the lower adhesive film 4 or not.

[0052] In some embodiments, Figure 2 and Figure 3 As shown, the protective component 6 includes a protective strip 61 and a protective baffle 62. The protective strip 61 is arranged around the perimeter of the sandwich assembly 7 along the height direction, and the protective baffle 62 is disposed on the upper end face of the protective strip 61 and the upper flexible metal sheet 2; this arrangement is mainly to prevent the honeycomb core 1 from collapsing.

[0053] The protective strip 61 is installed around the perimeter of the sandwich assembly 7, leaving a gap between the protective strip 61 and the honeycomb core 1. This arrangement ensures that the honeycomb core 1 does not collapse, and that the protective strip 61 will not affect the honeycomb core 1 after the sandwich assembly 7 has solidified, thus preventing any impact on the accuracy of the compression measurement of the sandwich assembly 7.

[0054] Optionally, there are four protective strips 61, and adjacent protective strips 61 are connected by a mortise and tenon structure.

[0055] Optionally, there are four protective baffles 62, which are connected end to end in sequence. Half of the protective baffle 62 rests on the remaining area of ​​the honeycomb core 1, and the other half rests on the protective baffle 61.

[0056] Furthermore, the gap between the protective strip 61 and the honeycomb core 1 is 1mm-2mm. Setting the gap between the protective strip 61 and the honeycomb core 1 within the above-mentioned range ensures that the protective strip 61 will not affect the cured honeycomb core 1, thereby affecting the accuracy of the compression measurement of the sandwich assembly 7. The gap between the protective strip 61 and the honeycomb core 1 can be selected as 1mm, 1.5mm, or 2mm, etc., according to actual needs.

[0057] In this embodiment, in order to ensure the structural strength of the protective strip 61, the material of the protective strip 61 is set to aluminum alloy or stainless steel, which has the advantages of good structural strength and corrosion resistance; at the same time, the material of the protective baffle 62 is set to glass fiber or carbon fiber, which has the advantages of strong heat resistance and good structural strength.

[0058] Specifically, S4 also includes: first encapsulating the part to be cured 8; then curing the encapsulated part to be cured 8 according to the curing curve of the autoclave prepreg. The part to be cured 8 is encapsulated according to a typical autoclave curing prepreg encapsulation method.

[0059] Furthermore, the process of encapsulating the workpiece 8 to be cured includes: encapsulating the workpiece 8 to be cured using a vacuum bag film and evacuating the vacuum bag film.

[0060] It should be noted that vacuum bagging is a molding process that seals the product between a mold and a vacuum bag, applying pressure by vacuuming to make the product more compact and with better mechanical properties. The specific steps include: 1. Mold preparation and application of release agent; 2. Product layering (hand lay-up, spraying, prepreg); 3. Laying release fabric; 4. Laying release film or perforated release film (optional); 5. Laying breathable felt; 6. Applying sealing strips (can be done in advance); 7. Sealing the vacuum bag film; 8. Installing vacuum valve, quick connector, and vacuum hose; 9. Connecting to the air source and checking the vacuum level; 10. Vacuuming and product curing; 11. Demolding the product.

[0061] In this embodiment, S4 further includes: after the curing of the workpiece 8 is completed, removing the protective component 6 of the cured workpiece 8, and then measuring the thickness H2 of the cured sandwich assembly 7, thereby ensuring the accuracy of the measurement.

[0062] An embodiment of the method for measuring the compression of a honeycomb core before and after curing according to the present invention is as follows: Grade 4 aramid paper honeycomb core material (nominal thickness 48 kg / m²) was selected. 3Taking this as an example, the two honeycomb core raw materials are roughly processed. The processing size can be determined according to the actual situation. Taking 200mm×100mm×50mm (where 50mm is the thickness direction of the honeycomb core) as an example; the upper flexible metal sheet 2 and the lower flexible metal sheet 5 are thin aluminum plates with a thickness of 2mm. The flexible metal sheet 2, the upper adhesive film 3, the honeycomb core 1, the lower adhesive film 4 and the lower flexible metal sheet 5 are sequentially laid on the flat tooling; the protective component 6 is installed, wherein the gap between the protective strip 61 and the honeycomb core 1 is 1mm-2mm, and the width of the protective baffle 62 is at least 40mm, half of which overlaps the honeycomb allowance area and half of which overlaps the protective strip 61; the part to be cured is sealed according to the vacuum bag process, and then cured according to the curing curve of the corresponding autoclave prepreg. Finally, the thickness of the sandwich assembly 7 after curing is measured. The difference in thickness direction of the sandwich assembly 7 before and after curing (i.e., the compression) is in the range of 0.2mm-0.3mm.

[0063] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for measuring the compression of a honeycomb core before and after curing, characterized in that, include: S1: Select the type and thickness of the honeycomb core (1); S2: Lay the flexible metal sheet (2), the upper adhesive film (3), the honeycomb core (1), the lower adhesive film (4) and the lower flexible metal sheet (5) in sequence to form a sandwich assembly (7), and measure the thickness H1 of the sandwich assembly (7) before curing; S3: The protective components (6) are arranged around the sandwich assembly (7) to form the part to be cured (8). S4: Curing the part to be cured (8) and measuring the thickness H2 of the sandwich assembly (7) after curing; S5: Calculate the compression S of the sandwich assembly (7) before and after curing, S=H1-H2; Both the upper flexible metal sheet (2) and the lower flexible metal sheet (5) are thin aluminum sheets or thin copper sheets; The protective component (6) includes a protective strip (61) and a protective plate (62). The protective strip (61) is arranged around the sandwich assembly (7) along the height direction of the sandwich assembly (7), and the protective plate (62) is disposed on the upper end face of the protective strip (61) and the upper flexible metal sheet (2). After the protective strip (61) is installed around the sandwich assembly (7), a gap is reserved between the protective strip (61) and the honeycomb core (1).

2. The method for measuring the compression of a honeycomb core before and after curing according to claim 1, characterized in that, The thickness of both the upper flexible metal sheet (2) and the lower flexible metal sheet (5) is 1.5mm-2.5mm.

3. The method for measuring the compression of a honeycomb core before and after curing according to claim 1, characterized in that, S2 also includes: Depending on the thickness of the adhesive film (3), the upper side of the honeycomb core (1) may be bonded to the upper flexible metal sheet (2) via the adhesive film (3) or not; and / or, Depending on the thickness of the lower adhesive film (4), the lower side of the honeycomb core (1) may be bonded to the lower flexible metal sheet (5) through the lower adhesive film (4) or not.

4. The method for measuring the compression of a honeycomb core before and after curing according to claim 1, characterized in that, The gap between the protective strip (61) and the honeycomb core (1) is 1mm-2mm.

5. The method for measuring the compression of a honeycomb core before and after curing according to claim 1, characterized in that, The protective strip (61) is made of aluminum alloy or stainless steel, and the protective baffle (62) is made of glass fiber or carbon fiber.

6. The method for measuring the compression of a honeycomb core before and after curing according to claim 1, characterized in that, S4 also includes: The part to be cured (8) is then encapsulated; The encapsulated part to be cured (8) is cured and molded according to the curing curve of the autoclave prepreg.

7. The method for measuring the compression of a honeycomb core before and after curing according to claim 1, characterized in that, Encapsulating the part to be cured (8) includes: The part to be cured (8) is sealed with a vacuum bag film and the vacuum bag film is evacuated.

8. The method for measuring the compression of a honeycomb core before and after curing according to claim 1, characterized in that, S4 also includes: Remove the protective component (6) from the cured part (8) and measure the thickness H2 of the cured sandwich assembly (7).

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