A method for forming a composite structure with a small R-angle box

Abstract

The present application relates to the technical field of composite material forming, in particular to a forming method of a composite material structure with a small R-angle box type. The method comprises the following steps: preparing a twist strip with the same geometric shape as the R-angle region, and pre-pressing the twist strip; placing the pre-pressed twist strip in the R-angle region of the first layer of prepreg, and using a pressing plate to adhere the twist strip to the first layer of prepreg; vacuum packaging the twist strip and the first layer of prepreg, and pre-pressing using a hot press; sequentially laying the remaining layers of prepreg, and using a pressing plate to compact the R-angle region during each layer of laying; after the laying is completed, vacuum packaging the whole, and curing in a hot press to obtain a composite material with a small R-angle box type structure. The forming method of the composite material structure with a small R-angle box type aims to solve the problem of poor R-angle forming quality of the negative mold forming of the composite material with a small R-angle box type structure.

Description

Technical Field

[0001] This invention relates to the field of composite material molding technology, and specifically to a molding method for a box-shaped composite material structural component with a small radius. Background Technology

[0002] When using a female mold to form box-shaped composite structural components, if the radius (R-corner) area is not sufficiently compacted, defects such as pores and delamination can easily occur between the carbon fiber prepreg layers during the curing process, leading to quality problems in the parts. A common solution is to use unidirectional prepreg to prepare twisted strips to fill the R-corner area, improving the molding quality of the parts.

[0003] For box-shaped composite materials with a small radius (r≤3mm), the radius is small, and the radius area is prone to bridging during the molding process. It is difficult to fully compact the carbon fiber prepreg layers. Simply using unidirectional prepreg to prepare twist strips to fill the radius area is difficult to compact and it is difficult to guarantee the quality of the product.

[0004] Therefore, the inventors provide a molding method for a box-shaped composite material structural component with a small radius. Summary of the Invention

[0005] (1) Technical problems to be solved

[0006] This invention provides a molding method for a box-shaped composite material structure with a small radius corner, which solves the technical problem of poor radius corner molding quality in the female mold molding of composite materials with a small radius corner box-shaped structure.

[0007] (2) Technical solution

[0008] This invention provides a molding method for a box-shaped composite material structural component with a small radius, comprising the following steps:

[0009] Prepare a twisted strip with the same geometry as the R-angle region, and pre-compress the twisted strip;

[0010] The pre-compressed twist strip is placed in the R-corner area of ​​the first layer of prepreg, and the twist strip is bonded to the first layer of prepreg using a pressure plate;

[0011] After vacuum sealing the twisted strip with the first layer of prepreg, a pre-pressing process is performed using an autoclave.

[0012] The remaining multi-layer prepreg is laid in sequence, and the R-corner area is compacted with a pressure plate when each layer is laid;

[0013] After the layup is completed, the entire structure is vacuum-sealed and cured in an autoclave to obtain a box-shaped composite material structural component with a small radius.

[0014] Furthermore, the preparation of the twisted strip having the same geometry as the R-angle region, and the pre-compression treatment of the twisted strip, specifically includes the following steps:

[0015] Based on the geometric parameters of the groove in the twist sliver mold, calculate the cross-sectional area of ​​the groove, measure the single-layer thickness of the unidirectional prepreg used, and calculate and cut out the required width of the unidirectional prepreg.

[0016] The unidirectional prepreg is rolled into a round strip along one side, placed in the groove of the twist strip mold, and the twist strip is pre-pressed.

[0017] Furthermore, the geometric parameters of the R-angle region of the box-shaped composite material molding die are extracted, and a twist strip mold with the same geometric parameters is manufactured.

[0018] Furthermore, the pre-compression process is as follows: temperature 50℃~60℃, heating rate ≤3℃ / min, curing pressure 0.6MPa~0.7MPa, pre-compression time 10min~20min, and cooling rate ≤3℃ / min.

[0019] Furthermore, the step of placing the pre-compressed twisted strip in the R-corner area of ​​the first layer of prepreg and using a pressure plate to bond the twisted strip to the first layer of prepreg specifically includes the following steps:

[0020] The first layer of prepreg after cutting is laid on the mold, the R-corner area is compacted using a pressure plate, and the first layer of prepreg is vacuumed after being sealed in a vacuum bag.

[0021] The pre-compressed twist strip is placed in the R-corner area, and the twist strip is heated to make it fit with the mold. The R-corner area is then initially compacted using a pressure plate.

[0022] After placing the twisted strip, seal it in a vacuum bag and pre-press it in an autoclave.

[0023] Furthermore, the vacuum pre-compression process is as follows: temperature 25℃±2℃, vacuum gauge pressure ≤-0.09MPa, time ≥10min.

[0024] Furthermore, the heating temperature for heating the twisted strip is ≤70℃, and the heating time is ≤1min.

[0025] Furthermore, the curing process is as follows: temperature 180±5℃, vacuum gauge pressure ≤-0.095MPa, curing pressure 0.6±0.035MPa, and curing time 120min~180min.

[0026] Furthermore, the heating rate is ≤3℃ / min, the cooling rate is ≤3℃ / min, and the temperature is reduced to below 60℃.

[0027] Furthermore, the twist strip is made of carbon fiber reinforced epoxy resin unidirectional prepreg.

[0028] (3) Beneficial effects

[0029] In summary, this invention prepares a twist strip mold by extracting the geometric parameters of the mold's radius (R-angle) region and pre-presses the twist strip, thus overcoming the poor quality of the radius (R-angle) region in the female mold forming of composite materials with small radius (R-angle) box-shaped structures. Attached Figure Description

[0030] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1(a) is a schematic diagram of the structure of a part without a film coating.

[0032] Figure 1(b) is a schematic diagram of the structure of a part with a film coating.

[0033] Figure 2 This is a schematic diagram of the structure of a twist strip mold provided in an embodiment of the present invention;

[0034] Figure 3 This is a schematic diagram illustrating the preparation of a twisted strip according to an embodiment of the present invention;

[0035] Figure 4 This is a schematic diagram of a composite material part layup structure provided in an embodiment of the present invention;

[0036] Figure 5 This is a schematic flowchart of a molding method for a box-shaped composite material structure with a small radius corner provided in an embodiment of the present invention.

[0037] In the picture:

[0038] 101-Non-film-coated surface; 102-Film-coated surface; 2-Twisting strip mold; 3-Twisting strip; 4-Part forming mold; 5-First layer prepreg; 6-Second layer prepreg; 7-Third layer prepreg; 8-Fourth layer prepreg; 9-Release film; 10-Glass cloth; 11-Vacuum bag; 12-Putty. Detailed Implementation

[0039] The embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and examples. The following detailed description of the embodiments and the accompanying drawings are used to illustrate the principles of the present invention by way of example, but should not be used to limit the scope of the present invention, that is, the present invention is not limited to the described embodiments.

[0040] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0041] In the description of this invention, it should be understood that the terms "upper," "lower," "front," "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use, or the orientation or positional relationship commonly understood by those skilled in the art. They are only used to facilitate the description of this invention and to simplify the description, and are not intended to 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.

[0042] Figure 5 This is a schematic flowchart of a molding method for a box-shaped composite material structure with a small radius corner provided in an embodiment of the present invention, as shown below. Figure 5 As shown, the method may include the following steps:

[0043] S100. Prepare a twisted strip with the same geometry as the R-angle region, and pre-compress the twisted strip.

[0044] S200. Place the pre-pressed twist strip in the R-corner area of ​​the first layer of prepreg, and use a pressure plate to bond the twist strip to the first layer of prepreg.

[0045] S300. After vacuum sealing the twist strip with the first layer of prepreg, pre-press it using an autoclave.

[0046] S400. Lay the remaining multi-layer prepreg in sequence, and use a pressure plate to compact the R-corner area when laying each layer.

[0047] After S500 and layering are completed, the entire structure is vacuum-sealed and cured in an autoclave to obtain a box-shaped composite material structural component with a small radius.

[0048] In the above embodiments, the twist strip mold is prepared by extracting the geometric parameters of the mold R-corner region and pre-pressing the twist strip, which overcomes the problems of poor R-corner region quality in the female mold forming of composite material with small R-corner box structure.

[0049] The structure of the final formed part is shown in Figure 1(a) and Figure 1(b), one is the non-film-coated surface 101 and the other is the film-coated surface 102.

[0050] As an optional implementation, in step S100, a twisted strip with the same geometry as the R-angle region is prepared, and the twisted strip is pre-compressed, specifically including the following steps:

[0051] S101. Based on the geometric parameters of the groove in the twist strip mold, calculate the cross-sectional area of ​​the groove, measure the single-layer thickness of the unidirectional prepreg used, and calculate and cut out the required width of the unidirectional prepreg.

[0052] S102. Twist the unidirectional prepreg into a round strip along one side, place it in the groove of the twist strip mold, and pre-press the twist strip.

[0053] In the above embodiments, the geometric parameters of the R-angle region of the box-shaped composite material molding die are extracted using 3D drawing software. A twist strip mold with the same geometric parameters is then machined using a CNC machine tool. The mold length is adjusted according to the part dimensions. The pre-compression method for the twist strip is not limited; a pressure cooker or press can be used for pre-compression.

[0054] like Figure 2-3 As shown, based on the geometric parameters of the groove in the twist sliver mold 2, the cross-sectional area of ​​the groove is calculated to be S (mm²). 2 The thickness of the single layer of the carbon fiber reinforced epoxy resin unidirectional prepreg used is measured to be h (mm). The required width w (mm) of the unidirectional prepreg is calculated and cut using formula (1). The unidirectional prepreg is rolled into a round strip along one side, placed in the groove of the twist strip mold, covered with a vacuum bag, and pre-pressed in a hot autoclave to form twist strip 3 for later use.

[0055]

[0056] As an optional implementation, the geometric parameters of the radius (R) corner region of the molded composite material for the box-shaped structure are extracted, and a groove with the same geometric parameters is machined on the composite material. This ensures that the groove can be perfectly matched and installed with the radius (R) corner region of the molded die.

[0057] As an optional implementation method, the pre-compression process is as follows: temperature 50℃~60℃, vacuum gauge pressure ≤ -0.09MPa, heating rate ≤ 3℃ / min, curing pressure 0.6MPa~0.7MPa, pre-compression time 10min~20min, and cooling rate ≤ 3℃ / min. The specific parameters of this process are selected according to the actual situation and will not be elaborated here.

[0058] As an optional implementation, in step S200, the pre-compressed twist strip is placed in the R-corner area of ​​the first layer of prepreg, and a pressure plate is used to bond the twist strip to the first layer of prepreg, specifically including the following steps:

[0059] S201. Lay the cut first layer of prepreg on the mold, use a pressure plate to compact the R-corner area, seal the vacuum bag and then vacuum the first layer of prepreg.

[0060] S202. Place the pre-compressed twist strip in the R-corner area, heat the twist strip to make it fit with the mold, and use a pressure plate to initially compact the R-corner area.

[0061] S203. After placing the twisted strip, seal it in a vacuum bag and pre-compress it in an autoclave.

[0062] like Figure 4 As shown, after the first layer of prepreg 5 is laid and compacted in the R-corner area of ​​the part forming mold 4, the tweezer strip 3 is placed in the R-corner area and compacted and bonded with the first layer of prepreg 5. Then, the second layer of prepreg 6, the third layer of prepreg 7, the fourth layer of prepreg 8, the release film 9, and the glass cloth 10 are laid in sequence. Then, the whole thing is sealed with a vacuum bag 11, and the interface between the vacuum bag 11 and the part forming mold 4 is sealed with putty 12.

[0063] As an optional implementation method, the vacuuming process is as follows: temperature 25℃±2℃, vacuum gauge pressure ≤-0.09MPa, time ≥10min. The specific parameters of this process are selected according to the actual situation and will not be elaborated here.

[0064] As an optional implementation, the heating temperature of the twist strip is ≤70℃ and the heating time is ≤1min. Specifically, a hot air gun can be used to heat the twist strip to make it easier for it to fit into the mold, and a pressure plate can be used to initially compact the R-corner area.

[0065] As an optional implementation method, the curing process is as follows: temperature 180±5℃, vacuum gauge pressure ≤-0.095MPa, curing pressure 0.6±0.035MPa, and curing time 120min~180min. The specific parameters of this process are selected according to the actual situation and will not be elaborated here.

[0066] As an optional implementation method, the heating rate is ≤3℃ / min, the cooling rate is ≤3℃ / min, and the temperature is reduced to below 60℃. The specific parameters of this process are selected according to the actual situation and will not be elaborated here.

[0067] As an optional implementation, the twist strip is made of carbon fiber reinforced epoxy resin unidirectional prepreg, and the mold material for the twist strip is high-temperature glass fiber reinforced epoxy resin composite material.

[0068] It should be noted that the various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. The present invention is not limited to the specific steps and structures described above and shown in the figures. Furthermore, for the sake of brevity, detailed descriptions of known methods and techniques are omitted here.

[0069] The above are merely embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art without departing from the scope of the invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of this application should be included within the scope of the claims of this application.

Claims

1. A molding method for a box-shaped composite material structural component with a small radius angle, characterized in that, The method includes the following steps: The preparation of a twisted strip with the same geometry as the R-angle region, and the pre-compression treatment of the twisted strip, specifically includes the following steps: Based on the geometric parameters of the groove in the twist sliver mold, calculate the cross-sectional area of ​​the groove, measure the single-layer thickness of the unidirectional prepreg used, and calculate and cut out the required width of the unidirectional prepreg. The unidirectional prepreg is rolled into a round strip along one side, placed in the groove of the twist strip mold, and the twist strip is pre-pressed. The pre-compressed twist strip is placed in the R-corner area of ​​the first layer of prepreg, and the twist strip is bonded to the first layer of prepreg using a pressure plate. The specific steps include the following: The first layer of prepreg after cutting is laid on the mold, the R-corner area is compacted using a pressure plate, and the first layer of prepreg is vacuumed after being sealed in a vacuum bag. The pre-compressed twist strip is placed in the R-corner area, and the twist strip is heated to make it fit with the mold. The R-corner area is initially compacted using a pressure plate. The heating temperature of the twist strip is ≤70℃ and the heating time is ≤1min. After the twisted strip is placed, it is sealed in a vacuum bag and pre-pressed in an autoclave. The remaining multi-layer prepreg is laid in sequence, and the R-corner area is compacted with a pressure plate when each layer is laid; After the layup is completed, the entire structure is vacuum-sealed and cured in an autoclave to obtain a box-shaped composite material structural component with a small radius.

2. The molding method for a box-shaped composite material structural component with a small radius corner according to claim 1, characterized in that, Extract the geometric parameters of the R-angle region of the box-shaped composite material molding die, and process a twist strip mold with the same geometric parameters.

3. The molding method for a box-shaped composite material structural component with a small radius corner according to claim 1, characterized in that, The pre-compression process is as follows: temperature 50℃~60℃, heating rate ≤3℃ / min, curing pressure 0.6MPa~0.7MPa, pre-compression time 10min~20min, and cooling rate ≤3℃ / min.

4. The molding method for a box-shaped composite material structural component with a small radius corner according to claim 1, characterized in that, The vacuum pre-compression process is as follows: temperature 25℃±2℃, vacuum gauge pressure ≤-0.09MPa, time ≥10min.

5. The molding method for a box-shaped composite material structural component with a small radius angle according to claim 1, characterized in that, The curing process is as follows: temperature 180±5℃, vacuum gauge pressure ≤-0.095MPa, curing pressure 0.6±0.035MPa, curing time 120min~180min.

6. The molding method for a box-shaped composite material structural component with a small radius angle according to claim 1 or 5, characterized in that, Heating rate ≤3℃ / min, cooling rate ≤3℃ / min, cooling down to below 60℃.

7. The molding method for a box-shaped composite material structural component with a small radius corner according to claim 1, characterized in that, The twist strip is made of carbon fiber reinforced epoxy resin unidirectional prepreg.

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