A carbon / carbon curved honeycomb structure, a manufacturing mold and a method thereof

Abstract

The present invention discloses a carbon / carbon curved honeycomb structure, a mold for preparing the structure, and a method for preparing the structure. The curved surfaces of the inner and outer surfaces of the curved honeycomb are two coaxial cylindrical surfaces. The curved honeycomb comprises a plurality of first and second single cell rings arranged alternately in the axial direction and connected in a mating manner. The first single cell ring comprises a plurality of first single cells connected in sequence in a mating manner, and the second single cell ring comprises a plurality of second single cells connected in sequence in a mating manner. The shape of the first single cell is the same as the solid shape formed by the intersection of a regular hexagonal pyramid, an inner cylindrical surface, and an outer cylindrical surface. The axis of the regular hexagonal pyramid is perpendicular to the axis of the inner cylindrical surface, the vertex of the regular hexagonal pyramid is on the axis of the inner cylindrical surface, and two pairs of sides of the base of the regular hexagonal pyramid are parallel to the axis of the inner cylindrical surface. The inner surface holes of the second single cells are hexagonal, identical in shape and size to the inner surface holes of the first single cells. The present invention simplifies the preparation process, saves labor time, and is suitable for the preparation of large-scale and batch carbon / carbon curved honeycombs.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon fiber ceramic matrix composite materials, and in particular to a carbon / carbon curved honeycomb structure, a mold and a method for preparing the structure. Background Art

[0002] As a new lightweight, high-strength structural material, carbon / carbon composites are being widely used in fields such as manned spaceflight and deep space exploration. Existing carbon / carbon honeycomb sandwich structures are often flat, significantly limiting their application. Furthermore, there is currently no satisfactory solution for lightweighting sectors, cylinders, and more complex quadratic and cubic curved surfaces.

[0003] How to comprehensively consider the preparation process of carbon / carbon composite materials and the structural form of curved honeycombs in view of the limitations of the preparation method of honeycomb sandwich structures is an urgent problem to be solved. Summary of the Invention

[0004] The purpose of the present invention is to provide a carbon / carbon curved honeycomb structure, a preparation mold and a method to solve the problems existing in the above-mentioned prior art. The preparation process is simple, labor-saving, and suitable for the preparation of large-scale and batch carbon / carbon curved honeycombs.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] The present invention provides a carbon / carbon curved honeycomb structure, wherein the curved surface on which the inner surface of the curved honeycomb is located is an inner cylindrical surface, and the curved surface on which the outer surface is located is an outer cylindrical surface coaxial with the inner cylindrical surface. The curved honeycomb includes a plurality of first and second single cell rings that are axially alternately arranged and matched with each other. The first single cell ring includes a plurality of first single cells that are matched with each other in sequence, and the second single cell ring includes a plurality of second single cells that are matched with each other in sequence. The shape of the first single cell is the same as the solid shape formed by the intersection of a regular hexagonal pyramid, the inner cylindrical surface, and the outer cylindrical surface, and the axis of the regular hexagonal pyramid is perpendicular to the axis of the inner cylindrical surface. The vertex of the regular hexagonal pyramid is on the axis of the inner cylindrical surface. Two pairs of sides of the base of the regular hexagonal pyramid are parallel to the axis of the inner cylindrical surface. The holes on the inner side surfaces of the second single cells are hexagons that are the same shape and size as the holes on the inner side surfaces of the first single cells. The angle between the side surfaces of the two bases of the regular hexagonal pyramid parallel to the axis of the inner cylindrical surface is 2π / n, where n is a positive integer ≥20.

[0007] Preferably, n≥36.

[0008] The present invention also provides a preparation mold for the carbon / carbon curved honeycomb structure described above, comprising a molding mold, wherein the molding mold comprises a male mold and a female mold that cooperate with each other, wherein the male mold is formed by placing half of the entity on a prismatic base in a linear array in the axial direction of the inner cylindrical surface, and half of the entity is obtained by cutting the entity with a symmetrical plane passing through the axis of the inner cylindrical surface, and half of the entity constitutes the male mold protrusion of the male mold, and a male mold groove portion is formed between the two male mold protrusions, and the length of the inner side of the bottom surface of the male mold groove portion is equal to the length of the side of the inner side of the male mold protrusion parallel to the axis of the inner cylindrical surface; the female mold is provided with a female mold protrusion and a female mold groove portion that cooperate with the male mold protrusion and the male mold groove portion respectively, and after the male mold and the female mold are matched and connected, the tooth surface formed by the male mold protrusion and the male mold groove portion is completely fitted with the tooth surface formed by the female mold protrusion and the female mold groove portion.

[0009] Preferably, it also includes an assembly mold, which includes a mold base and a mold roller. The mold base is provided with a semi-cylindrical groove, and the mold roller is rotatably set in the semi-cylindrical groove and is coaxially arranged with the semi-cylindrical groove. The gap between the semi-cylindrical surface of the semi-cylindrical groove and the outer peripheral surface of the mold roller is equal to the gap width between the outer cylindrical surface and the inner cylindrical surface.

[0010] Preferably, the outer peripheral surface of the mold roller is roughened or covered with anti-slip material to increase its friction coefficient, and the semi-cylindrical surface of the semi-cylindrical groove is smoothed or covered with smooth material to reduce its friction coefficient.

[0011] The present invention also provides a method for preparing the carbon / carbon curved honeycomb structure described above, which is beneficial for preparing a mold for the carbon / carbon curved honeycomb structure described above, comprising the following steps:

[0012] S1: Laying the prepreg strips on the male mold, pressing the female mold downward to compact the prepreg strips, and closing the molds to obtain an assembly consisting of the male mold, the female mold, and the prepreg strips;

[0013] S2: placing the assembly obtained in step 1 in a flat vulcanizer for hot pressing to obtain corrugated board strips;

[0014] S3: Repeat steps S1-S2 to obtain a plurality of corrugated board strips;

[0015] S4: placing a corrugated board strip on the upper edge of the semi-cylindrical groove in a direction parallel to the axis and close to the outer peripheral surface of the mold roller, and applying adhesive on the convex surface of the corrugated board strip to form a bonding surface;

[0016] S5: rotating the mold roller and the corrugated board strip together at an angle so that the bonding surface is parallel to the upper edge of the mold base, taking another corrugated board strip and placing it symmetrically with the previous corrugated board strip and bonding it, and applying adhesive on the convex surface of the newly bonded corrugated board strip to make it a new bonding surface;

[0017] S6: Repeat step S5 until a curved honeycomb is bonded to the outer circumference of the mold roller, and solidify the curved honeycomb in a heating container;

[0018] S7: removing the mold roller to separate the curved honeycomb from the mold roller;

[0019] S8: Densification of curved honeycomb using chemical vapor deposition process.

[0020] Preferably, in step S1, a release agent is applied to the male mold and the female mold or a release cloth is placed on the male mold, and then a prepreg strip is laid on the male mold.

[0021] Preferably, the adhesive is modified phenolic resin.

[0022] Preferably, in step S1, the prepreg strip is a straight strip, and its width is consistent with the thickness of the molding die.

[0023] Compared with the prior art, the present invention has achieved the following technical effects:

[0024] 1. The molding die of the present invention is long and strip-shaped, occupies a small space, is suitable for industrialized, large-scale hot pressing to prepare corrugated board strips for bonding curved honeycombs, and has high production efficiency.

[0025] 2. The present invention bonds the corrugated board strips together through an assembly mold to achieve overall preparation, eliminate the influence of gravity, and make the resulting product more regular in shape.

[0026] 3. The corrugated board strips of the present invention can be fully extended in the direction of the curved honeycomb axis to achieve integrated preparation of the structure, thereby effectively improving its mechanical properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. 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 any creative work.

[0028] Figure 1 A three-dimensional schematic diagram of the carbon / carbon curved honeycomb structure provided by the present invention;

[0029] Figure 2A front view of the carbon / carbon curved honeycomb structure provided by the present invention;

[0030] Figure 3 A top view of the carbon / carbon curved honeycomb structure provided by the present invention;

[0031] Figure 4 A schematic diagram of the molding die provided by the present invention;

[0032] Figure 5 A schematic diagram of an assembly mold provided by the present invention;

[0033] Figure 6 An exploded view of the assembly mold provided by the present invention;

[0034] Figure 7 Schematic diagram of a solid body formed by the intersection of a regular hexagonal pyramid, an inner cylindrical surface, and an outer cylindrical surface in the present invention;

[0035] Figure 8 For cutting Figure 7 The schematic diagram of the raised part of the male mold is obtained from the solid;

[0036] Figure 9 This is a schematic front view of the process of bonding corrugated board strips into a curved honeycomb in the present invention;

[0037] Figure 10 It is a side view schematic diagram of the process of bonding corrugated board strips into a curved honeycomb in the present invention.

[0038] In the figure: 1-first single cell ring, 101-first single cell, 2-second single cell ring, 201-second single cell, 3-regular hexagonal pyramid, 4-inner cylindrical surface, 401-central axis, 5-outer cylindrical surface, 6-solid, 7-molding mold, 8-male mold, 9-female mold, 10-prismatic base, 11-male mold protrusion, 12-male mold groove, 13-female mold groove, 14-female mold protrusion, 15-symmetry plane, 16-assembly mold, 17-mold base, 18-mold roller, 19-semi-cylindrical groove, 20-corrugated board strip. DETAILED DESCRIPTION

[0039] like Figures 1-10As shown, the present invention provides a carbon / carbon curved honeycomb structure, wherein the curved surface of the inner surface of the curved honeycomb is an inner cylindrical surface 4, and the curved surface of the outer surface is an outer cylindrical surface 5 coaxial with the inner cylindrical surface 4. The curved honeycomb includes a plurality of first single cell rings 1 and second single cell rings 2 that are alternately arranged in the axial direction and connected in a coordinated manner. The first single cell ring 1 includes a plurality of first single cells 101 that are sequentially connected in a coordinated manner, and the second single cell ring 2 includes a plurality of second single cells 201 that are sequentially connected in a coordinated manner. The shape of the first single cell 101 is consistent with that of a regular hexagonal pyramid 3, the inner cylindrical surface 4, and the outer cylindrical surface 5. The solid body 6 formed by the intersection has the same shape, and the axis of the regular hexagonal pyramid 3 is perpendicular to the axis of the inner cylindrical surface 4, the vertex of the regular hexagonal pyramid 3 is on the central axis 401 of the inner cylindrical surface 4, and there are two pairs of sides in the base of the regular hexagonal pyramid 3 that are parallel to the axis of the inner cylindrical surface 4. The hole on the inner surface of the second unit cell 201 is a hexagon with the same shape and size as the hole on the inner surface of the first unit cell 101. The angle between the side surfaces of the two bases of the regular hexagonal pyramid 3 parallel to the central axis 401 of the inner cylindrical surface 4 is 2π / n, where n is a positive integer ≥20.

[0040] As an embodiment of the present invention, n≥36, preferably 36≤n≤72.

[0041] The present invention provides a mold for preparing the carbon / carbon curved honeycomb structure described above, comprising a pressing mold 7, wherein the pressing mold 7 comprises a male mold 8 and a female mold 9 that cooperate with each other, wherein the male mold 8 is formed by placing half of a solid body 6 in a linear array in the direction of the central axis 401 of the inner cylindrical surface 4 on a prismatic base 10, wherein the half of the solid body 6 is obtained by cutting the solid body 6 along a symmetry plane 15 passing through the central axis 401 of the inner cylindrical surface 4, wherein the half of the solid body 6 constitutes a male mold protrusion 11 of the male mold 8, and the two male mold protrusions A male mold groove portion 12 is formed between the male mold portions 11, and the length of the inner side of the bottom surface of the male mold groove portion 12 is equal to the length of the inner side of the male mold protrusion 11 parallel to the axis of the inner cylindrical surface 4; the female mold 9 is provided with a female mold groove portion 13 and a female mold protrusion 14 respectively cooperating with the male mold protrusion 11 and the male mold groove portion 12. After the male mold 8 and the female mold 9 are matched and connected, the tooth surface formed by the male mold protrusion 11 and the male mold groove portion 12 is completely fitted with the tooth surface formed by the female mold protrusion 14 and the female mold groove portion 13.

[0042] As an embodiment of the present invention, it also includes an assembly mold 16, which includes a mold base 17 and a mold roller 18. The mold base 17 is provided with a semi-cylindrical groove 19. The mold roller 18 is rotatably set in the semi-cylindrical groove 19 and is coaxially arranged with the semi-cylindrical groove 19. The gap between the semi-cylindrical surface of the semi-cylindrical groove 19 and the outer peripheral surface of the mold roller 18 is equal to the gap width between the outer cylindrical surface 5 and the inner cylindrical surface 4.

[0043] As an embodiment of the present invention, the pressing mold 7 and the assembly mold 16 are made of stainless steel or other materials with good rigidity to ensure good molding accuracy of the curved honeycomb.

[0044] As an embodiment of the present invention, the outer peripheral surface of the mold roller 18 is roughened or covered with anti-slip material to increase its friction coefficient, and the semi-cylindrical surface of the semi-cylindrical groove 19 is smoothed or covered with smooth material to reduce its friction coefficient.

[0045] As an embodiment of the present invention, the anti-slip material is preferably a rubber anti-slip material.

[0046] As an embodiment of the present invention, the smooth material is preferably a polyimide smooth material.

[0047] The present invention provides a method for preparing the carbon / carbon curved honeycomb structure described above, which is beneficial for preparing a mold for the carbon / carbon curved honeycomb structure described above, comprising the following steps:

[0048] S1: Lay the prepreg strips on the male mold 8, press the female mold 9 downward to compact the prepreg strips, and complete the mold closing to obtain an assembly consisting of the male mold 8, the female mold 9 and the prepreg strips;

[0049] S2: placing the assembly obtained in step 1 in a flat vulcanizer for hot pressing to obtain corrugated board strips;

[0050] S3: Repeat steps S1-S2 to obtain a plurality of corrugated board strips 20;

[0051] S4: Place a corrugated board strip 20 on the upper edge of the semi-cylindrical groove 19 in a direction parallel to the axis and close to the outer peripheral surface of the mold roller 18, and apply adhesive on the convex surface of the corrugated board strip 20 to make it a bonding surface;

[0052] S5: Rotate the mold roller 18 and the corrugated board strip 20 together at an angle so that the bonding surface is parallel to the upper edge of the mold base 17, take another corrugated board strip 20 and place it symmetrically with the previous corrugated board strip 20 and bond it, and apply adhesive on the convex surface of the newly bonded corrugated board strip 20 to make it a new bonding surface;

[0053] S6: Repeat step S5 until a curved honeycomb is formed by bonding the outer circumference of the mold roller 18, and solidifying the curved honeycomb in a heating container;

[0054] S7: Remove the mold roller 18 to separate the curved honeycomb from the mold roller 18;

[0055] S8: Densification of curved honeycomb using chemical vapor deposition process.

[0056] As an embodiment of the present invention, in step S1 , a release agent is applied or a release cloth is placed on the male mold 8 and the female mold 9 , and then the prepreg strips are laid on the male mold 8 .

[0057] As an embodiment of the present invention, the adhesive is modified phenolic resin.

[0058] As an embodiment of the present invention, in step S1 , the prepreg strip is a straight strip, and its width is consistent with the thickness of the molding die 7 .

[0059] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0060] Example 1

[0061] Prepare as Figure 4-Figure 6 The molding die 7 and the assembly die 16 shown are as follows: the molding die 7 is 500 mm long and 20 mm wide, the side length of the tooth surface is about 50.42 mm, the number of teeth per layer is 36, and the prepreg strip is a phenolic prepreg with a resin content of 42%.

[0062] The specific preparation process of the carbon / carbon composite curved honeycomb structure is as follows:

[0063] Step 1: Place the molding die 7 in an oven, heat it to 45°C, and keep it warm for 30 minutes; cut rectangular prepreg strips, apply polyimide mold release agent on the surfaces of the male mold 8 and the female mold 9, lay the prepreg strips on the male mold 8, press the female mold 9 down to compact the prepreg strips, and fully close the mold to obtain an assembly consisting of the male mold 8, the female mold 9, and the prepreg strips;

[0064] Step 2: Place the assembly on a flat vulcanizer, heat it from room temperature to 80°C at a rate of 1°C / min, apply pressure of 0.5 MPa and keep it at 80°C for 30 minutes, then heat it to 160°C at a rate of 1°C / min and keep it at that temperature for 120 minutes; after cooling it to room temperature, demould it, and obtain the corrugated board strip 20;

[0065] Step 3: Repeat steps 1-2 to obtain a plurality of corrugated board strips 20;

[0066] Step 4: Place a corrugated board strip 20 on the upper edge of the semi-cylindrical groove 19 in a direction parallel to the axis and close to the outer peripheral surface of the mold roller 18, and apply adhesive on the convex surface of the corrugated board strip 20 to form a bonding surface; the adhesive is obtained by modifying phenolic resin;

[0067] Step 5: Rotate the mold roller 18 and the corrugated board strip 20 together at an angle so that the bonding surface is parallel to the upper edge of the mold base 17, take another corrugated board strip 20 and place it symmetrically with the previous corrugated board strip 20 and bond it, and apply adhesive on the convex surface of the newly bonded corrugated board strip 20 to make it a new bonding surface;

[0068] Step 6: Repeat step 5 until the curved honeycomb is bonded to the outer surface of the mold roller 18, and first keep it in an oven at 80°C for 30 minutes, then increase the temperature to 180°C and keep it for 120 minutes to solidify the curved honeycomb.

[0069] Step 7: Remove the mold roller 18 to separate the curved honeycomb from the mold roller 18;

[0070] Step 8: Use chemical vapor deposition process to densify the curved honeycomb. Place the entire curved honeycomb in a CVI deposition furnace, heat it to 800°C at a rate of 1°C / min, and heat treat it in a nitrogen atmosphere for 120 minutes; then heat it to 950°C at a rate of 1°C / min, first create a vacuum environment and then introduce propylene gas, maintain the pressure at 1 kPa, and run it continuously for 100 hours to obtain the required carbon / carbon curved honeycomb structure.

[0071] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A carbon / carbon curved honeycomb structure, characterized by: The curved surface of the inner surface of the curved honeycomb is an inner cylindrical surface, and the curved surface of the outer surface is an outer cylindrical surface coaxial with the inner cylindrical surface. The curved honeycomb includes a plurality of first single cell rings and second single cell rings that are axially alternately arranged and matched. The first single cell ring includes a plurality of first single cells matched and connected in sequence, and the second single cell ring includes a plurality of second single cells matched and connected in sequence. The shape of the first single cell is the same as the solid shape formed by the intersection of a regular hexagonal pyramid, the inner cylindrical surface and the outer cylindrical surface, and the axis of the regular hexagonal pyramid is perpendicular to the axis of the inner cylindrical surface, the vertex of the regular hexagonal pyramid is on the axis of the inner cylindrical surface, and there are two pairs of sides in the base of the regular hexagonal pyramid that are parallel to the axis of the inner cylindrical surface. The holes on the inner surface of the second single cell are hexagons of the same shape and size as the holes on the inner surface of the first single cell. The angle between the side surfaces of the two bases parallel to the axis of the inner cylindrical surface in the regular hexagonal pyramid is 2π / n, and n is a positive integer ≥20; The carbon / carbon curved honeycomb structure is prepared by a preparation mold, which includes a molding mold, and the molding mold includes a male mold and a female mold that cooperate with each other. The male mold is formed by placing half of the entity on a prismatic base in a linear array in the axial direction of the inner cylindrical surface. Half of the entity is obtained by cutting the entity with a symmetry plane passing through the axis of the inner cylindrical surface. Half of the entity constitutes the male mold protrusion of the male mold, and a male mold groove portion is formed between the two male mold protrusions. The length of the inner side of the bottom surface of the male mold groove portion is equal to the length of the side of the inner side of the male mold protrusion parallel to the axis of the inner cylindrical surface; the female mold is provided with a female mold groove portion and a female mold protrusion portion respectively cooperating with the male mold protrusion and the male mold groove portion. After the male mold and the female mold are coupled and connected, the tooth surface formed by the male mold protrusion and the male mold groove portion is completely fitted with the tooth surface formed by the female mold protrusion and the female mold groove portion.

2. The carbon / carbon curved honeycomb structure according to claim 1, wherein: n≥36。 3. The carbon / carbon curved honeycomb structure according to claim 1, wherein: The preparation mold also includes an assembly mold, which includes a mold base and a mold roller. The mold base is provided with a semi-cylindrical groove, and the mold roller is rotatably set in the semi-cylindrical groove and is coaxially arranged with the semi-cylindrical groove. The gap between the semi-cylindrical surface of the semi-cylindrical groove and the outer peripheral surface of the mold roller is equal to the gap width between the outer cylindrical surface and the inner cylindrical surface.

4. The carbon / carbon curved honeycomb structure according to claim 3, characterized in that: The outer peripheral surface of the mold roller is roughened or covered with anti-skid material to increase its friction coefficient, and the semi-cylindrical surface of the semi-cylindrical groove is smoothed or covered with smooth material to reduce its friction coefficient.

5. A method for preparing a carbon / carbon curved honeycomb structure according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1: Laying the prepreg strips on the male mold, pressing the female mold downward to compact the prepreg strips, and closing the molds to obtain an assembly consisting of the male mold, the female mold, and the prepreg strips; S2: placing the assembly obtained in step 1 in a flat vulcanizer for hot pressing to obtain corrugated board strips; S3: Repeat steps S1-S2 to obtain a plurality of corrugated board strips; S4: placing a corrugated board strip on the upper edge of the semi-cylindrical groove in a direction parallel to the axis and close to the outer peripheral surface of the mold roller, and applying adhesive on the convex surface of the corrugated board strip to form a bonding surface; S5: rotating the mold roller and the corrugated board strip together at an angle so that the bonding surface is parallel to the upper edge of the mold base, taking another corrugated board strip and placing it symmetrically with the previous corrugated board strip and bonding it, and applying adhesive on the convex surface of the newly bonded corrugated board strip to make it a new bonding surface; S6: Repeat step S5 until a curved honeycomb is bonded to the outer circumference of the mold roller, and solidify the curved honeycomb in a heating container; S7: removing the mold roller to separate the curved honeycomb from the mold roller; S8: Densification of curved honeycomb using chemical vapor deposition process.

6. The method for preparing a carbon / carbon curved honeycomb structure according to claim 5, wherein: In step S1, a release agent is applied to the male mold and the female mold or a release cloth is placed on the male mold, and then a prepreg strip is laid on the male mold.

7. The method for preparing a carbon / carbon curved honeycomb structure according to claim 5, wherein: The adhesive is modified phenolic resin.

8. The method for preparing a carbon / carbon curved honeycomb structure according to claim 5, wherein: In step S1 , the prepreg strip is a straight strip, and its width is consistent with the thickness of the molding die.

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