Metal embedded parts and embedded method in composite material cylinder structure

Abstract

The present invention discloses a metal embedded part and an embedding method in a composite material cylindrical composite material structure. The metal embedded part is arc-shaped and consists of metal embedded skirts at both ends and a metal embedded part body raised in the middle. The thickness of the metal embedded part body is greater than the metal embedded skirt, and the metal embedded skirt is provided with a hollow step. The structural settings such as the metal embedded part body, the metal embedded skirt and the hollow step, as well as the embedding method, are all suitable for various types of aerospace composite material cylindrical structural parts, and have the advantages of simple structure, simple molding process, high reliability, high structural rigidity, and small assembly workload.

Description

Technical Field

[0001] The invention relates to the field of composite materials and metal part pre-embedding methods, in particular to a metal pre-embedding part in a composite material cylinder structure and a pre-embedding method. Background Art

[0002] Most aerospace cylindrical composite products use metal parts as processing and assembly interfaces. Therefore, the main direction of aerospace composite product structure design is to use composite materials in the main load-bearing parts and metal parts as the connection parts. The connection part between composite materials and metal materials is the weakest part of the entire product structure. Currently, the connection and composite materials between composite materials and metal parts are mainly completed by gluing, mechanical connection opening, and pre-embedded metal parts.

[0003] The prior art discloses a composite metal integrated pull rod and its forming method, which is a Chinese patent with the announcement number CN106741835A. The pull rod includes a metal component and a composite material component, wherein one end of the metal component is a connection functional area, and the other end is an anti-slip embedded area. The outer surface of the anti-slip embedded area is wavy and contains a number of annular grooves. The cross section of the groove is an inverted isosceles trapezoid. The anti-slip embedded area is connected to the composite material in an integral molding. During molding, carbon fiber woven fabric prepregs are alternately laid on the periphery of the embedded area, and unidirectional prepregs are used to wrap around the troughs for reinforcement. Finally, the mold is pressurized and cured in an autoclave. In this method, annular grooves are designed on the metal parts. Although the bonding effect is increased to a certain extent, the dense and short grooves increase the difficulty and effect of laying the prepreg.

[0004] The prior art also discloses a composite wall panel structure with embedded support parts, which is a Chinese patent with the announcement number CN106239936A. The structure includes a metal joint, a support part, an inner skin, an outer skin and a foam layer, wherein the support part and the foam layer form a combination, and the inner skin, the outer skin and the combination are cured to form a composite wall panel assembly, and the support part is placed in the composite wall panel assembly, and the metal joint is connected to the composite wall panel assembly by a blind rivet; this method adds a metal rivet to the embedded assembly, which increases the process and requires destruction of the composite structure.

[0005] If the bonding strength between the metal pre-set parts and the composite materials is not good during the bonding process, the metal parts may slip or be dislocated. The integrity between the metal parts and the composite materials is poor, and the airtightness of the cylindrical composite products cannot be guaranteed. The metal parts cannot be used as load-bearing structures. Some pre-embedded parts still need to be auxiliary connected by mechanical connection, which destroys the overall structure. Summary of the Invention

[0006] In order to solve the above technical problems, the present invention provides a metal embedded part and an embedding method in a composite material cylinder structure.

[0007] The present invention is achieved through the following technical solutions.

[0008] The present invention provides a metal embedded part in a composite material cylindrical structure. The metal embedded part is arc-shaped and consists of metal embedded skirts at both ends and a metal embedded part body raised in the middle. The thickness of the metal embedded part body is greater than the metal embedded skirt, and the metal embedded skirt is provided with a hollow step.

[0009] Preferably, a threaded connection hole is provided on the metal embedded part body.

[0010] Preferably, the arc surface of the metal embedded part body fits the arc surface of the cylindrical composite material.

[0011] Preferably, the hollow steps are arranged in a double-gradient hollowed-out manner in the X and Z coordinate directions, and the number of hollow steps on each side is set to 2 to 4.

[0012] Another aspect of the present invention provides a method for pre-embedding metal embedded parts in a composite cylindrical structure, comprising the following steps:

[0013] S1: Before the metal embedded parts are embedded and installed, the metal embedded skirt is hollowed out with double gradients;

[0014] S2: Pre-embedded metal parts are treated before embedding, including pickling and sandblasting the surface of the metal embedded parts, followed by anodizing and cleaning of the metal embedded parts.

[0015] S3: Then, epoxy film is sprayed on the surrounding surfaces of the metal embedded part body, the metal embedded skirt and the hollow step, and then placed in a natural environment and sent to an oven for drying;

[0016] S4: According to the size of the tubular composite material, the size of the metal embedded parts, the embedded position and the laying design requirements, prepreg sheets of different sizes, angles and structures are cut out;

[0017] S5: Lay out the complete prepreg sheets according to the layup design requirements to form an inner skin on the surface of the cylindrical composite material. The number of prepreg sheets laid out on the inner skin is 4 to 8 layers;

[0018] S6: When the metal embedded part body and the metal embedded skirt are pre-embedded and installed, the metal embedded part body and the metal embedded skirt are fitted on the surface of the cylindrical composite material. The metal embedded part body and the metal embedded skirt are bonded to the inner skin paved with prepreg sheets according to the designed positions of the cylindrical composite material using an adhesive, and are left to stand for a certain period of time to complete room temperature curing;

[0019] S7: Apply glue twice to the four walls and surface of the hollow steps, and then use the cut prepreg to lay and fill the hollow steps until they are at the same height as the embedded metal skirt;

[0020] S8: Apply glue twice to the exposed metal parts of the metal embedded parts;

[0021] S9: The prepreg material with the holes cut to the size of the main body of the metal embedded part is laid around and on the upper part of the metal embedded part until the overall thickness of the composite material tube is met.

[0022] Preferably, the metal pre-embedded skirt is embedded between the inner skin and the outer skin of the cylindrical composite material.

[0023] Preferably, the anodizing treatment is phosphoric acid anodizing treatment.

[0024] Preferably, the thickness of the epoxy film spraying is 0.2-1 mm.

[0025] Preferably, when filling the hollow step part, glue is first applied to the penetrating part along the Z-axis direction and prepreg is laid. After the prepreg is flush with the plane of the first step, glue is continued to be applied to the surface of the first step and the four walls, and prepreg is laid. The above actions are repeated until the filling is flush with the entire metal embedded skirt.

[0026] Preferably, when laying the outer skin, 3 to 5 layers of prepreg are laid, and the entire preform is subjected to vacuum pre-compaction treatment.

[0027] The beneficial effects of the present invention are:

[0028] 1. The metal pre-embedded skirt is pre-embedded between the outer skin and the inner skin by bonding, and the four walls and surfaces of the hollow step are coated with glue. The cut prepreg is paved and filled into the hollow step until it is at the same height as the metal pre-embedded skirt. Under the action of the stepped multi-layer reinforcement, a continuous and uninterrupted connection is achieved during the prepreg paving process, and the connection between the metal pre-embedded skirt and the tubular composite material is reinforced, thereby reinforcing the connection between the metal pre-embedded part body and the tubular composite material. At the same time, the bottom part of the metal pre-embedded part body is also pre-embedded in the tubular composite material by bonding the outer skin and the inner skin, further reinforcing the connection between the technical pre-embedded part body and the tubular composite material, strengthening the bonding strength between the two, avoiding the metal pre-embedded part body from slipping and dislocation on the tubular composite material as much as possible, and ensuring that the metal pre-embedded part body is used as a load-bearing structure.

[0029] 2. By spraying epoxy film on the metal pre-embedded body, the problem of deformation of the metal pre-embedded body due to the different thermal expansion coefficients of the metal pre-embedded body and the tubular composite material during high-temperature curing is solved as much as possible. At the same time, the problem of micro gaps between the metal pre-embedded body and the composite material is avoided as much as possible. The connection between the metal part and the prepreg is achieved through film-to-film connection, which further enhances its airtightness and connection reliability.

[0030] 3. Use pre-cut prepregs with the size of metal parts for overall paving, thereby reducing damage to the integrity of the prepregs and avoiding waste of prepregs. At the same time, it also reduces the number of prepreg seams, improves the integrity of the metal embedded part body and the tubular composite material, and improves the performance of the composite material product after molding.

[0031] 4. The structural settings and embedding methods such as the metal embedded part body, metal embedded skirt and hollow steps are all suitable for various types of aerospace composite tubular structural parts. They have the advantages of simple structure, simple molding process, high reliability, high structural rigidity and small assembly workload. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a structural schematic diagram of the present invention;

[0033] Figure 2 It is a schematic diagram of the overall process of the present invention;

[0034] Description of the accompanying drawings: 100 - metal embedded part body; 200 - threaded connection hole; 300 - hollow step; 400 - metal embedded skirt. DETAILED DESCRIPTION

[0035] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0036] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0037] In the examples of this application, refer to Figure 1The metal embedded part is arc-shaped and consists of metal embedded skirts 400 at both ends and a raised metal embedded part body 100 in the middle. The thickness of the metal embedded part body 100 is greater than the metal embedded skirt 400. The metal embedded part body 100 is provided with threaded connection holes 200. There are four threaded connection holes 200, two in a group, and the two groups of threaded connection holes 200 are symmetrically distributed for connecting external components. The curvature of the metal embedded part body 100 is 15° to 30°, so that the arc surface of the metal embedded part body 100 fits with the outer arc surface of the cylindrical composite material.

[0038] In the examples of this application, refer to Figure 1 The metal embedded skirt 400 and the metal embedded part body 100 are formed as one piece by welding. The thickness of the metal embedded skirt 400 is 0.8 to 1.2 mm, and the curvature of the metal embedded skirt 400 is 10° to 15°, so that the metal embedded skirt 400 can fit the outer arc surface of the tubular composite material. The metal embedded skirt 400 is provided with a hollow step 300. The hollow step 300 adopts a double-gradient step hollowing arrangement in the X and Z coordinate directions. The number of steps of the hollow step 300 on each side is set to 2 to 4 sections. The hollow step 300 and the metal embedded skirt 400 are also provided with a through portion to facilitate filling of prepreg and facilitate subsequent connection between the metal embedded skirt 400 and the surface of the tubular composite material.

[0039] The preferred embodiment of the present invention also provides a method for pre-embedding metal embedded parts in a composite cylindrical structure, referring to Figure 2 , including the following steps:

[0040] S1: Before the metal embedded parts are embedded and installed, the 400 part of the metal embedded skirt is subjected to double gradient hollowing treatment;

[0041] S2: Pre-embedding treatment of the metal embedded part, performing surface pickling and sandblasting on the metal embedded part body 100, then performing anodizing treatment on the treated metal embedded part body 100, and completing cleaning of the metal embedded part body 100;

[0042] S3: Then, the surrounding surfaces of the metal embedded part body 100, the metal embedded skirt 400 and the hollow step 300 are sprayed with epoxy film, and then placed in a natural environment and sent to an oven for drying;

[0043] S4: According to the size of the tubular composite material, the size and position of the metal embedded parts and the paving design requirements, prepreg sheets of different sizes, angles and structures are cut to reduce the waste of prepreg sheets;

[0044] S5: Lay out the complete prepreg sheets according to the layup design requirements to form an inner skin on the surface of the tubular composite material. The number of prepreg sheets laid out on the inner skin is 4 to 8 layers, so that the inner skin is laid tightly and the close connection between the metal embedded parts and the tubular composite material is strengthened.

[0045] S6: When the metal embedded part body 100 and the metal embedded skirt 400 are embedded and installed, the metal embedded part body 100 and the metal embedded skirt 400 are placed on the cylindrical composite material. The metal embedded part body 100 and the metal embedded skirt 400 are bonded to the inner skin paved with prepreg sheets according to the designed position of the cylindrical composite material using an adhesive, and are left to stand for a certain period of time to complete room temperature curing;

[0046] S7: Apply glue twice to the four walls and surface of the hollow step 300, and then use the cut prepreg to fill the hollow step 300. Along the Z-axis direction, first apply glue to the through part and lay the prepreg. After the prepreg is flush with the plane of the first step, continue to apply glue to the surface and four walls of the first step and lay the prepreg. Repeat the above steps until it is filled flush with the entire metal embedded skirt 400; so that the metal embedded skirt 400 is embedded between the inner and outer skins of the tubular composite material. Under the action of the stepped multi-layer reinforcement, a continuous and uninterrupted connection is achieved during the prepreg laying process, thereby strengthening the connection between the metal embedded skirt 400 and the tubular composite material.

[0047] S8: Apply glue twice to the exposed metal part of the metal embedded component body 100 to facilitate the prepreg around the metal embedded component body 100 so that the embedded metal component is embedded to a depth of 0.8 to 1.2 mm;

[0048] S9: The prepreg material with the size of 100 holes reserved for the main body of the metal embedded part is laid around and on the upper part of the metal embedded part until the overall thickness of the composite tubular composite material is met to form the outer skin of the tubular composite material. When laying the outer skin, 3 to 5 layers of prepreg are laid, and the entire preform is vacuumed and pre-compacted.

[0049] The anodizing treatment adopted is phosphoric acid anodizing treatment, and the anodizing treatment can also be nitric acid anodizing treatment, so as to achieve the cleaning of the metal embedded parts and facilitate the subsequent operation of the metal embedded parts.

[0050] An epoxy film is sprayed on the metal embedded part body 100 with a thickness of 0.2 to 1 mm to solve the problem of deformation of the metal embedded part body 100 due to the different thermal expansion coefficients when the metal embedded part body 100 and the tubular composite material are cured at high temperature. At the same time, the problem of micro gaps between the metal embedded part body 100 and the composite material is avoided as much as possible.

[0051] The working principle of this embodiment is as follows: the number of prepreg sheets laid on the inner skin of the cylindrical composite material is 4 to 8 layers, so that the inner skin is laid tightly on the surface of the cylindrical composite material, and the metal embedded part body 100 and the metal embedded skirt 400 are connected to the inner skin by bonding;

[0052] The four walls and surface of the hollow step 300 are coated with glue for the second time, and then the cut prepreg is used to fill the hollow step 300. Along the Z-axis direction, the through parts are first coated with glue and prepreg is laid. After the prepreg is flush with the plane of the first step, glue is continued to be applied to the surface and four walls of the first step, and prepreg is laid. The above steps are repeated until the filling is flush with the entire embedded part skirt. Under the effect of the stepped multi-layer reinforcement, a continuous and uninterrupted connection is achieved during the prepreg laying process, thereby strengthening the connection between the metal embedded part skirt and the cylindrical composite material, thereby strengthening the connection between the metal embedded part body 100 and the cylindrical composite material.

[0053] When laying the outer skin, every time 3 to 5 layers of prepreg are laid, the entire preform is vacuumed and pre-compacted. The bottom part of the metal embedded part is also embedded in the tubular composite material by bonding the outer skin and the inner skin, further strengthening the connection between the main body of the technical embedded part and the tubular composite material, strengthening the bonding strength between the two, and avoiding the metal embedded part from slipping and dislocation on the tubular composite material as much as possible, while ensuring that the metal embedded part is used as a load-bearing structure.

[0054] The above are only preferred embodiments of the present invention and are not intended to limit the patent scope of the present invention. All equivalent structural transformations made based on the contents of the present invention's description and drawings, or direct / indirect applications in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A method for pre-embedding metal embedded parts in a composite tubular composite material structure, characterized in that: The method comprises the following steps: S1: The metal embedded part is arc-shaped, and the metal embedded part consists of metal embedded skirts (400) at both ends and a metal embedded part body (100) protruding in the middle. The thickness of the metal embedded part body (100) is greater than that of the metal embedded skirt (400). A threaded connection hole (200) is provided on the metal embedded part body (100). Before the metal embedded part is embedded and installed, the metal embedded skirt (400) is subjected to a double-gradient hollowing treatment. A hollow step (300) is provided on the metal embedded skirt (400). The hollow step (300) is arranged in a double-gradient hollowing arrangement in the X and Z coordinate directions, and the number of steps of the hollow step (300) on each side is set to 2 to 4 sections; S2: pre-embedded metal parts, performing surface pickling and sandblasting on the metal embedded part body (100), then performing anodizing on the treated metal embedded part body (100), and completing cleaning of the metal embedded part body (100); S3: Then, epoxy film is sprayed on the surrounding surfaces of the metal embedded part body (100), the metal embedded skirt (400) and the hollow step (300), and then placed in a natural environment and sent to an oven for drying; S4: According to the size of the tubular composite material, the size of the metal embedded parts, the embedded position and the laying design requirements, prepreg sheets of different sizes, angles and structures are cut out; S5: Lay out the complete prepreg sheets according to the layup design requirements to form an inner skin on the surface of the cylindrical composite material. The number of prepreg sheets laid out on the inner skin is 4 to 8 layers; S6: When the metal embedded part body (100) and the metal embedded skirt (400) are embedded and installed, the metal embedded part body (100) and the metal embedded skirt (400) are fitted on the surface of the cylindrical composite material, the arc surface of the metal embedded part body (100) fits the arc surface of the cylindrical composite material, and the metal embedded part body (100) and the metal embedded skirt (400) are bonded to the inner skin paved with prepreg sheets according to the designed position of the cylindrical composite material using an adhesive, and are left to stand for a certain period of time to complete room temperature curing; S7: Apply glue twice to the four walls and the surface of the hollow step (300), and then use the cut prepreg to lay and fill the hollow step (300) until it is at the same height as the metal embedded skirt (400); S8: Applying glue a second time to the exposed metal portion of the metal embedded part body (100); S9: The prepreg material with the hole of the size of the metal embedded part body (100) is cut and laid around and on the upper part of the metal embedded part until the overall thickness of the composite material cylindrical composite material is met.

2. The method for pre-embedding metal embedded parts in a composite cylindrical structure according to claim 1, characterized in that: The metal pre-embedded skirt (400) is embedded between the inner skin and the outer skin of the composite material.

3. The method for pre-embedding metal embedded parts in a composite cylindrical structure according to claim 1, characterized in that: The anodizing treatment is phosphoric acid anodizing treatment.

4. The method for pre-embedding metal embedded parts in a composite cylindrical structure according to claim 1, characterized in that: The thickness of epoxy film spraying is 0.2~1mm.

5. The method for pre-embedding metal embedded parts in a composite cylindrical structure according to claim 1, characterized in that: When filling the hollow step (300), first apply glue to the through part along the Z-axis direction and lay the prepreg. After the prepreg is flush with the plane of the first step, continue to apply glue to the surface of the first step and the four walls, and lay the prepreg. Repeat the above steps until the filling is flush with the entire metal embedded skirt (400).

6. The method for pre-embedding metal embedded parts in a composite cylindrical structure according to claim 1, characterized in that: When laying the outer skin, lay 3 to 5 layers of prepreg and perform vacuum pre-compaction on the entire preform.

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