Orthogonal structure core material and preparation method thereof

Abstract

The invention provides an orthogonal structure core material and a preparation method thereof, and relates to the technical field of material compositing, in order to solve the problem that in the prior art, the sharp corner position of an R area cannot be effectively filled, and a cavity is formed, the orthogonal structure core material comprises multiple sets of blank layers, and the multiple sets of blank layers are equal in thickness and unequal in width; the multiple sets of blank layers are stacked from bottom to top, the widths of the multiple sets of blank layers are gradually reduced or gradually increased, and the center lines of the multiple sets of blank layers are located on the same vertical line. The matching degree of the shape of the core material of the orthogonal structure and the R area of the composite component is high, and the problems that filling is insufficient due to the fact that the core material is wrapped with air in a traditional rolling and twisting mode, nondestructive faults occur at the position of the R area, and apparent faults caused by insufficient ironing are avoided.

Description

Technical Field

[0001] The invention relates to the technical field of material composites, and in particular to an orthogonal structure core material and a preparation method thereof. Background Art

[0002] With the continuous development of aviation manufacturing technology, fiber-reinforced resin-based composite materials such as carbon fiber and glass fiber have been widely used due to their high specific strength, specific modulus, good fatigue resistance and corrosion resistance, and have replaced metals in some key parts. However, during the production and use of composite materials, it is inevitable that defects such as delamination, debonding, and inclusions will occur. These defects will seriously affect the mechanical properties and overall integrity of composite components. Various non-destructive testing methods are important means to ensure the reliable use of composite materials. In order to meet the requirements of structural design and reduce manufacturing costs, more and more integrally formed composite components are widely used, and R transition zones are common in these complex structures. The R transition zone is a curved surface with a small spatial size, which is very unfavorable for defect detection. At the same time, the R zone is mostly a stress concentration area, with a low tolerance for defects, and defects are very likely to occur during the manufacturing process. Therefore, quality control of the R zone is very important.

[0003] Existing composite structural parts are usually filled with unidirectional tape prepreg at the R zone 101 position, such as Figure 1 and Figure 2 As shown, in actual production, the unidirectional tape prepreg 103 of corresponding size is cut, and the unidirectional tape prepreg 103 is rolled perpendicular to the unidirectional tape fiber direction to form a cylindrical unidirectional tape prepreg core material. When used, the cylindrical unidirectional tape prepreg core material is placed in the composite material R area 101, and the cylindrical core material is pressed with a hot iron, and cured together with the remaining material layers 102.

[0004] The following defects exist in the preparation and use of conventional core materials: a. The unidirectional tape prepreg 103 is easily entrained with air during the rolling process, and the air is not easy to be discharged, resulting in insufficient compaction inside the prepared unidirectional tape prepreg core material, causing a non-destructive failure in the R zone 101 position of the cured composite material structure; b. When the core material is pressed with a hot iron, the sharp corner position of the R zone 101 cannot be effectively filled, resulting in a cavity at this position, causing a non-destructive failure in the cured composite material at the sharp corner position of the R zone 101; c. When the core material is pressed with a hot iron, the core material cannot be effectively compacted, and a bulge appears in the R zone 101, resulting in a bulge on the surface of the cured composite material component, which does not meet the appearance requirements or assembly requirements; d. The fibers of the prepared core material are all in the same direction, and the strength along the fiber direction is relatively high. The non-fiber direction is resin-connected and the strength is insufficient. After the composite material component is cured and receives stress, the core material will be stressed and cracked in the non-fiber direction, causing a non-destructive failure in the R zone 101 position of the cured composite material. Summary of the invention

[0005] The purpose of the present invention is to provide an orthogonal structural core material and a preparation method thereof, so as to solve the problem in the prior art that the sharp corners of the R zone cannot be effectively filled, resulting in the formation of cavities. The shape of the orthogonal structural core material of the present invention has a high degree of matching with the R zone of the composite material component, avoiding the core material being enclosed in air due to the traditional rolling method, resulting in insufficient filling, causing lossless failures in the R zone, and avoiding apparent failures caused by insufficient ironing.

[0006] The present invention provides an orthogonal structural core material, comprising multiple groups of blank layers, wherein the thickness of the multiple groups of blank layers is equal and the width is different, the multiple groups of blank layers are stacked from bottom to top and the width gradually decreases or increases, and the midlines of the multiple layers of the blank layers are on the same vertical line.

[0007] As a preferred solution of the present invention, the blank layer comprises multiple layers of unidirectional tape prepreg, and the multiple layers of unidirectional tape prepreg are stacked at different layering angles.

[0008] As a preferred embodiment of the present invention, the ply angle of the orthogonal structural core material is [45° / 0° / -45° / 90°].

[0009] As a preferred solution of the present invention, the blank layer includes 4 layers of unidirectional tape prepreg.

[0010] The present invention also provides a method for preparing an orthogonal structure core material, which is used to prepare the orthogonal structure core material, comprising the steps of: A. Cut unidirectional tape prepreg; B. stacking multiple layers of the unidirectional tape prepreg according to different layering angles, and the multiple layers of the unidirectional tape prepreg form a blank layer; C. Cutting the blank layers of different widths according to the size of the composite material R region, stacking the blank layers of different widths upward or downward in sequence and keeping them aligned in the middle, and forming a core material blank with multiple blank layers; D. Place the core material blank into the core material forming mold and form it by hot pressing.

[0011] As a preferred embodiment of the present invention, in step B: multiple layers of the unidirectional tape prepreg are stacked at a stacking angle of [45° / 0° / -45° / 90°].

[0012] As a preferred embodiment of the present invention, in step B: the stacked multi-layer unidirectional tape prepreg is sealed in a vacuum bag and the stacked layers are pre-vacuumed, the pre-vacuum degree is ≥-0.085Mpa, and the pre-vacuum time is ≥15min.

[0013] As a preferred embodiment of the present invention, the minimum width of the blank layer in step C is 2 mm, and the multiple blank layers form an inverted pyramid-shaped core material blank.

[0014] As a preferred solution of the present invention, the core material forming mold includes a forming pressure plate and a core material mold assembly, and the core material mold assembly is provided with an extrusion groove adapted to the R zone of the composite material component, and the extrusion groove opening is set upward, and the forming pressure plate is pressed onto the core material mold assembly and seals the upper opening of the extrusion groove.

[0015] As a preferred solution of the present invention, the core material mold assembly includes a plurality of core material mold units, which are connected side by side and close to each other, and chamfers adapted to the R zone of the composite material component are respectively arranged on both sides of the top of the core material mold unit, and the chamfers between two adjacent core material mold units are spliced ​​to form the extrusion groove; the core material mold assembly also includes a fixing bolt, and a transverse through-hole is arranged on the core material mold unit, and the through-holes on the plurality of core material mold units are arranged correspondingly, and the fixing bolt passes through the through-holes on the plurality of core material mold units to fix the plurality of core material mold units in connection.

[0016] Compared with the prior art, the present invention has the following positive effects: The orthogonal structural core material provided by the present invention comprises a plurality of groups of blank layers, the thickness of the plurality of groups of blank layers being equal and the width being different, the plurality of groups of blank layers being stacked from bottom to top and the width being gradually reduced or gradually increased, and the midlines of the plurality of layers of blank layers being on the same vertical line. The orthogonal structural core material of the present invention is provided with stacked blank layers, the width of the blank layers being increased layer by layer according to the R size of the core material mold assembly, and being stacked into an inverted pyramid-shaped orthogonal structural core material, the two sides of the stacked orthogonal structural core material forming the orthogonal structural core material forming the orthogonal structural core material forming the orthogonal structural core material formed by stacking the plurality of groups of blank layers being similar in size to the R zone of the composite material component, and having a high degree of matching with the R zone of the composite material component, avoiding the core material encapsulation caused by the traditional rolling and rubbing method leading to insufficient filling, causing lossless failure at the R zone position, avoiding the apparent failure caused by insufficient ironing, and solving the internal lossless problem and the external surface quality problem caused by the traditional core material preparation method. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 It is a schematic diagram of the location of the R zone of the composite material structure; Figure 2 This is a schematic diagram of traditional core material preparation; Figure 3It is a structural schematic diagram of the core material forming mold of the present invention; Figure 4 It is a plan view schematic diagram of the core material forming mold of the present invention; Figure 5 It is a schematic diagram of the orthogonal structure core material stacking in the present invention. In the figure: 101, R zone; 102, material layer; 103, unidirectional tape prepreg; 201, extrusion groove; 202, core material mold unit; 203, perforation; 204, forming platen; 3, orthogonal structure core material; 31, blank layer. DETAILED DESCRIPTION

[0019] In the description of the present invention, it should be noted that, unless otherwise specified, "plurality" means two or more than two; the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside", "outside", "front end", "back end", "head", "tail" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, which is only for the convenience of describing the present invention and simplification, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", "third" and the like are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0020] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0021] The specific implementation modes of the present invention are further described in detail below with reference to the accompanying drawings.

[0022] Embodiment 1: This embodiment provides an orthogonal structure core material, such as Figure 5 As shown, it includes multiple groups of blank layers 31, and the thickness of the multiple groups of blank layers 31 is equal and the width is different. The multiple groups of blank layers 31 are stacked from bottom to top and the width gradually decreases or increases. The midlines of the multiple layers of blank layers 31 are on the same vertical line, so that the orthogonal structure core material 3 forms a left-right symmetrical pyramid structure.

[0023] like Figure 5As shown, the blank layer 31 includes 8 groups of blank layers 31, and the minimum width of the stacked blank layers 31 is set to 2 mm. After the blank layers 31 with a width of 2 mm are stacked, the width of the blank layers 31 is increased layer by layer according to the size of the core material mold assembly R, and stacked into an inverted pyramid-shaped orthogonal structure core material.

[0024] In this embodiment, the two sides of the stacked orthogonal core material 3 form a stepped structure. The orthogonal core material 3 formed by stacking multiple groups of blank layers 31 is similar in size to the R zone of the composite material component, so as to facilitate extrusion molding through the extrusion groove 201.

[0025] As a preferred implementation mode, Figure 5 As shown, the blank layer 31 includes multiple layers of unidirectional tape prepreg 103, which are stacked at different layer angles. The unidirectional tape prepreg 103 is a carbon fiber material layer, and the multiple layers of unidirectional tape prepreg 103 are stacked at different layer angles, so that the blank layer 31 has excellent structural strength in all directions.

[0026] According to the thickness of a single layer of material, each blank layer 31 is stacked with 4 layers of unidirectional tape prepreg, and the prepreg angles are [45° / 0° / -45° / 90°].

[0027] As a preferred embodiment, the ply angle of the orthogonal structural core material 3 is [45° / 0° / -45° / 90°]. Preferably, 4 layers of unidirectional tape prepreg constitute a group of blank layers 31. The 4 layers of unidirectional tape prepreg are respectively ply-laid at angles of 45° / 0° / -45° / 90°.

[0028] The angles of the orthogonal structural core material 3 in this embodiment are designed using a [45° / 0° / -45° / 90°] scheme, and the orthogonal angle design is used to ensure that the core material has good structural strength in all directions.

[0029] This embodiment also provides a method for preparing an orthogonal structure core material, which is used to prepare the orthogonal structure core material 3, comprising the steps of: A. Cutting unidirectional tape prepreg; the quantity of the cut unidirectional tape prepreg can be set according to the demand.

[0030] B. Multiple layers of the unidirectional tape prepreg are stacked at different laying angles to form a blank layer. The multiple layers of unidirectional tape prepreg stacked at different laying angles enable the prepared core material to have excellent structural strength in all directions, ensuring that the composite material component will not crack or have other faults at that position after being subjected to force.

[0031] C. Cut the blank layers of different widths according to the size of the R zone of the composite material, stack the blank layers of different widths upward or downward in sequence and keep them aligned in the middle, and multiple blank layers form a core material blank; blank layers of different widths are stacked in sequence to form a pyramid structure with steps on both sides, so that the core material blank is consistent with the size of the R zone of the composite material.

[0032] D. Place the core material blank into the core material forming mold and form it by hot pressing. Specifically, according to the properties of the core material, set the hot pressing parameters (the hot pressing temperature is set near the Tg of the prepreg resin), and send the core material forming mold and the core material blank into the hot press tank for hot pressing. The method of hot pressing in the tank makes the prepared orthogonal structure core material more matched with the R zone, avoiding non-destructive failure caused by insufficient filling and apparent failure caused by insufficient ironing.

[0033] After demoulding, an orthogonal structural core material whose shape matches the shape of the R zone of the composite material component is obtained; after the remaining material layers 102 of the composite part are stacked, the mold is closed, and an orthogonal structural core material 3 whose shape matches that of the composite material component is placed at the R zone 101 to complete the assembly of the composite material part; the vacuum bag is sealed, and the composite material part is cured according to the established curing parameters.

[0034] As a preferred embodiment, in step B: multiple layers of the unidirectional tape prepreg are stacked at a ply angle of [45° / 0° / -45° / 90°]. Specifically, the unidirectional tape prepreg has 4 layers, and the 4 layers of unidirectional tape prepreg are stacked at an angle of 45° / 0° / -45° / 90° respectively.

[0035] As a preferred embodiment, in step B: the stacked multi-layer unidirectional tape prepreg is sealed in a vacuum bag and the stacked layers are pre-vacuumed, the pre-vacuum degree is ≥-0.085Mpa, and the pre-vacuum time is ≥15min. After the pre-vacuuming, the multi-layer unidirectional tape prepreg is compacted to facilitate the cutting operation in the subsequent steps.

[0036] Specifically, after cutting out the required blank layers of different widths, the vacuum bag is removed and the blank layers of different widths are stacked up or down in sequence and kept aligned in the middle. Specifically, eight blank layers of different widths can be cut out.

[0037] As a preferred embodiment, the minimum width of the blank layer in step C is 2 mm, and the multiple blank layers form an inverted pyramid-shaped core material blank. Then the inverted pyramid-shaped core material blank is placed in a core material forming mold, and then the core material forming mold after the core material blank is placed is placed in a vacuum bag, sealed and evacuated, and then sent to an autoclave for hot pressing.

[0038] As a preferred implementation mode, Figure 3-Figure 5As shown, the core material forming mold includes a forming platen 204 and a core material mold assembly, on which an extrusion groove 201 adapted to the R zone of the composite material component is arranged, the extrusion groove 201 opening is arranged upward, and the forming platen 204 is pressed onto the core material mold assembly and seals the upper opening of the extrusion groove 201.

[0039] When the core material forming mold of this embodiment is used, the profile on the core material mold assembly is placed in the extrusion groove 201, and then the forming platen 204 is covered to extrusion-form the core material, and the shape and size of the extrusion groove 201 are adapted to the shape and size of the R region of the composite material component. After the core material is extruded and formed by the forming platen 204 and the core material mold assembly, the shape and size of the R region of the composite material component are adapted. After the core material is demolded from the core material mold assembly, the formed core material is placed at the R region 101 of the composite material component to complete the assembly.

[0040] The shape of the core material prepared in this embodiment has a high degree of matching with the R region of the composite material component, avoiding the core material entrained air caused by the traditional rolling method, resulting in insufficient filling, causing a lossless fault at the R region 101 position, and avoiding the apparent fault caused by insufficient ironing. The internal lossless problem and the external surface quality problem caused by the traditional core material preparation method are solved.

[0041] As a preferred embodiment, the core material mold assembly includes a plurality of core material mold units 202, and the plurality of core material mold units 202 are connected side by side. Chamfers that match the R region of the composite material component are respectively arranged on both sides of the top of the core material mold unit 202, and the chamfers between two adjacent core material mold units 202 are spliced ​​to form an extrusion groove 201. The bottom surface of the core material mold unit 202 is a plane, which is convenient for horizontal arrangement. The core material mold unit 202 is made of a pressure-resistant material with a high pressure-bearing strength, and can be made of steel.

[0042] In this embodiment, multiple core material mold units 202 are spliced ​​to form multiple extrusion grooves 201, so that the core material mold assembly can prepare multiple core materials at the same time, thereby improving the preparation efficiency. In addition, the multiple core material mold units 202 are detachably connected to each other, so that after the core material is extruded, it is easy to demold by separating the two core material mold units 202, so that the shape of the core material remains consistent and is not affected by demolding.

[0043] As a preferred embodiment, the core material mold assembly further includes a fixing bolt, and a transverse through hole 203 is provided on the core material mold unit 202, and the through holes 203 on the multiple core material mold units 202 are correspondingly provided. The fixing bolt passes through the through holes 203 on the multiple core material mold units 202 to fix and connect the multiple core material mold units 202. The shapes and sizes of the multiple core material mold units 202 are the same. The shape and size of the core material mold unit 202 are designed according to the size of the R zone of the composite material component.

[0044] The multiple core material mold units 202 in this embodiment are connected and fixed together by fixing bolts penetrating through the bottom thereof, so that the connection is tight and the assembly and disassembly are convenient.

[0045] The preparation method of the orthogonal structure core material 3 in this embodiment is as follows: a. Cut the unidirectional tape prepreg 103 of corresponding size; b. Lay 4 layers of unidirectional tape prepreg at a laying angle of [45° / 0° / -45° / 90°], and seal the vacuum bag to pre-evacuate the layers after the laying is completed. The pre-evacuation degree is ≥-0.085Mpa, and the pre-evacuation time is ≥15min; c. According to the size design drawing of the orthogonal structure core material 3, cut the blank with a width of L8, and cut the blanks with sizes of L7-L1 in turn; d. Place the blank with a width of L8 on a plane, and stack the blanks with sizes of L7-L1 upward in turn, keep the blanks of each size aligned in the middle, and stack them into an inverted pyramid shape; e. Place the inverted pyramid-shaped blanks on the core material Place a forming platen 204 in the extrusion groove 201 of the forming mold; f. seal the core material forming mold after placing the core material blank into a vacuum bag; g. set the hot pressing parameters (the hot pressing temperature is set near the prepreg resin Tg) in combination with the properties of the core material, and send the forming platen 204, the core material mold assembly and the orthogonal structure core material 3 into the autoclave for hot pressing; h. demoulding to obtain an orthogonal structure core material whose shape matches the shape of the R zone 101 of the composite material component; i. after completing the stacking of the remaining material layers 102 of the composite material component, close the mold, place the orthogonal structure core material 3 matching the shape of the R zone 101 of the composite material component at the R zone 101 position, and complete the assembly; j. seal the vacuum bag and cure the composite material component according to the established curing parameters.

[0046] The core material forming mold in this embodiment adds unidirectional tape prepreg of other fiber angles when preparing the core material, so that the prepared core material has excellent structural strength in all directions, ensuring that the composite material component will not crack or other faults at this position after being subjected to force; at the same time, it avoids the lossless fault at the R zone 101 caused by the core material being enclosed in air due to the traditional rolling method; the core material and the R zone 101 are better matched by extruding the pressing plate 204 and the core material mold assembly by hot pressing in the tank.

[0047] The above is only a preferred embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make several modifications and improvements without departing from the creative concept of the present invention, which should be included in the protection scope of the present invention.

Claims

1. An orthogonal structural core material, characterized in that: It comprises a plurality of groups of blank layers (31), the thickness of the plurality of groups of blank layers (31) being equal and the width being different, the plurality of groups of blank layers (31) being stacked from bottom to top and the width gradually decreasing or increasing, and the center lines of the plurality of groups of blank layers (31) being on the same vertical line.

2. The orthogonal structural core material according to claim 1, characterized in that: The blank layer (31) comprises multiple layers of unidirectional tape prepreg, and the multiple layers of unidirectional tape prepreg are stacked at different layering angles.

3. The orthogonal structural core material according to claim 2, characterized in that: The ply angle of the orthogonal structural core material (3) is [45° / 0° / -45° / 90°].

4. The orthogonal structural core material according to claim 2, characterized in that: The blank layer (31) comprises four layers of unidirectional tape prepreg.

5. A method for preparing an orthogonal structure core material, characterized in that: The method for preparing the orthogonal structural core material according to any one of claims 1 to 4 comprises the steps of: A. Cut unidirectional tape prepreg; B. stacking multiple layers of the unidirectional tape prepreg according to different layering angles, and the multiple layers of the unidirectional tape prepreg form a blank layer; C. Cutting the blank layers of different widths according to the size of the composite material R region, stacking the blank layers of different widths upward or downward in sequence and keeping them aligned in the middle, and forming a core material blank with multiple blank layers; D. Place the core material blank into the core material forming mold and form it by hot pressing.

6. The method for preparing an orthogonal structure core material according to claim 5, characterized in that: In step B: multiple layers of the unidirectional tape prepreg are stacked at a stacking angle of [45° / 0° / -45° / 90°].

7. The method for preparing an orthogonal structure core material according to claim 6, characterized in that: In step B: the stacked multi-layer unidirectional tape prepreg is sealed in a vacuum bag and the stacked layers are pre-vacuumed, the pre-vacuum degree is ≥-0.085Mpa, and the pre-vacuum time is ≥15min.

8. The method for preparing an orthogonal structure core material according to claim 6, characterized in that: The minimum width of the blank layer in step C is 2 mm, and the multiple blank layers form an inverted pyramid-shaped core material blank.

9. The method for preparing an orthogonal structure core material according to claim 6, characterized in that: The core material forming mould comprises a forming pressing plate (204) and a core material mould assembly, an extrusion groove (201) adapted to the R region of the composite material component is arranged on the core material mould assembly, the extrusion groove (201) is opened upward, and the forming pressing plate (204) is pressed onto the core material mould assembly and seals the upper opening of the extrusion groove (201).

10. The method for preparing an orthogonal structure core material according to claim 9, characterized in that: The core material mold assembly comprises a plurality of core material mold units (202), the plurality of core material mold units (202) are connected side by side and close to each other, chamfers matching the R region of the composite material component are respectively arranged on both sides of the top of the core material mold unit (202), and the chamfers between two adjacent core material mold units (202) are spliced ​​to form the extrusion groove (201); the core material mold assembly also comprises a fixing bolt, a transverse through hole (203) is arranged on the core material mold unit (202), the through holes (203) on the plurality of core material mold units (202) are arranged correspondingly, and the fixing bolt passes through the through holes (203) on the plurality of core material mold units (202) to fix and connect the plurality of core material mold units (202).

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