CN109435273B - Method and bonding die for bonding variable-thickness composite material framework and skin - Google Patents
Method and bonding die for bonding variable-thickness composite material framework and skin Download PDFInfo
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- CN109435273B CN109435273B CN201811157575.9A CN201811157575A CN109435273B CN 109435273 B CN109435273 B CN 109435273B CN 201811157575 A CN201811157575 A CN 201811157575A CN 109435273 B CN109435273 B CN 109435273B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
- B29C70/04—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts comprising reinforcements only, e.g. self-reinforcing plastics
- B29C70/28—Shaping operations therefor
- B29C70/30—Shaping by lay-up, i.e. applying fibres, tape or broadsheet on a mould, former or core; Shaping by spray-up, i.e. spraying of fibres on a mould, former or core
- B29C70/34—Shaping by lay-up, i.e. applying fibres, tape or broadsheet on a mould, former or core; Shaping by spray-up, i.e. spraying of fibres on a mould, former or core and shaping or impregnating by compression, i.e. combined with compressing after the lay-up operation
- B29C70/342—Shaping by lay-up, i.e. applying fibres, tape or broadsheet on a mould, former or core; Shaping by spray-up, i.e. spraying of fibres on a mould, former or core and shaping or impregnating by compression, i.e. combined with compressing after the lay-up operation using isostatic pressure
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
- B29C70/04—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts comprising reinforcements only, e.g. self-reinforcing plastics
- B29C70/28—Shaping operations therefor
- B29C70/54—Component parts, details or accessories; Auxiliary operations, e.g. feeding or storage of prepregs or SMC after impregnation or during ageing
Abstract
The invention discloses a method and a die for bonding a variable-thickness composite material framework and a skin, and belongs to the technology of resin-based structure composite material molding. The bonding method comprises the following steps: after the second surface of the framework and the first surface of the skin are processed, respectively sticking a layer of adhesive film, wherein the first surface and the second surface face opposite directions, and spreading the adhesive film surface on the framework by adopting hot-melt prepreg to obtain a first framework to be bonded; the method comprises the steps of arranging first side baffles around a first outline die, forming a cavity of a framework and a skin bonding piece, putting the skin into the cavity, aligning and attaching a second surface of the skin to an upper surface of the first outline die, stacking a first to-be-bonded framework on the skin, aligning an elastic layer of a first cover plate to a first surface of the framework, fastening the first side baffles and the first cover plate, curing and completing bonding. The invention realizes the bonding molding of the framework skin structure, has high bonding quality and effectively ensures the pneumatic appearance of the product.
Description
Technical Field
The invention belongs to a resin-based structure composite material forming technology, and particularly relates to a high-temperature-resistant resin-based composite material double-curvature frame skin structure bonding mold and a forming method.
Background
The rapid development of aerospace structure composite materials and the further requirements of new models on structure weight reduction and structure efficiency are met, the forming technology of the structural composite materials is a focus, the structural composite material technology is a key supporting technology of a transportation system in China, is an important factor for determining the performance, quality and reliability of aerospace products, and the performance and level of the structural composite materials have very important influence on the development of aerospace technologies and the development process of aerospace products.
As the reusable aircraft in China puts forward the requirements of light weight, integration and high temperature resistance, the composite material has the characteristics of double curvature appearance and complex structure, as shown in fig. 1, a wing made of composite material of a certain model is composed of a variable-thickness integral framework 100 made of composite material and skins (a lower skin 200 and an upper skin 300) arranged on two sides of the framework, the framework is composed of an upper frame, a lower frame and a plurality of groups of vertical plates 3, wherein the heights of the vertical plates are different, the upper frame is formed by a plurality of first frame strips 11 to form a multi-lattice structure, the lower frame is formed by a plurality of second frame strips 21 to form the multi-lattice structure, the first frame strips 11 correspond to the second frame strips 21 one by one, the vertical plates 3 are arranged between the opposite first frame strips 11 and the second frame strips 21, the vertical sections of the first frame strips 11 and the second frame strips 21 are in an I-shaped structure.
In a conventional framework skin structure, a framework is usually made of metal materials, the framework and the skin are generally fixedly connected through a fastener, in the framework skin structure shown in fig. 1, the framework and the skin are both made of composite materials, and in view of weight reduction, the framework and the skin are preferably selected to be fixedly combined in a bonding mode.
Disclosure of Invention
The invention aims to provide a method and a die for bonding a variable-thickness composite material framework and a skin, which are used for realizing bonding forming of a framework skin structure, have high bonding quality and effectively ensure the pneumatic appearance of a product.
The purpose of the invention is realized by the following technical scheme.
A method for bonding a variable-thickness composite material framework and a skin comprises the following steps:
1) preparing a bonding device, wherein the bonding die comprises a first outer die, a first side baffle and a first cover plate, the inner profile surface of the first cover plate is matched with the first surface of the framework and is provided with an elastic layer, and the upper surface of the first outer die is matched with the second surface of the skin;
2) dipping the carbon fiber cloth reinforcement into resin glue solution to prepare hot-melt prepreg;
3) after the second surface of the framework and the first surface of the skin are processed, respectively sticking a layer of adhesive film, wherein the first surface and the second surface face opposite directions;
4) paving the surface of an adhesive film on the framework by adopting the hot-melt prepreg to obtain a first framework to be bonded;
5) arranging the first side baffle plates around the first outline mold to form a cavity of a framework and skin bonding piece, placing the skin into the cavity, aligning and attaching the second surface of the skin to the upper surface of the first outline mold, stacking the first to-be-bonded framework on the skin, aligning the elastic layer of the first cover plate to the first surface of the framework, and fastening the first side baffle plates and the first cover plate to obtain a first assembly mold;
6) and curing the first assembling die to finish bonding.
In an optional embodiment, the skin includes a first skin and a second skin respectively located at two sides of the framework, an upper surface of the first outer mold is matched with a second surface of the first skin, the bonding mold further includes a second outer mold, a second side baffle and a second cover plate, an inner molding surface of the second cover plate is matched with the second surface of the first skin and is provided with an elastic layer, and an upper surface of the second outer mold is matched with the first surface of the second skin, and the bonding method includes:
bonding the framework and the first skin according to the steps 1) to 6) to obtain a semi-finished product;
then carrying out the following steps:
7) after the first surface of the framework and the second surface of the second skin are processed, respectively pasting a layer of adhesive film;
8) paving the adhesive film surface on the first surface of the framework by using the hot-melt prepreg, and bonding the framework to be bonded;
9) arranging the second side baffle plates around the second outer mold to form a cavity of a framework, a first skin and a second skin bonding piece, placing the second skin into the cavity to enable the first surface of the second skin to be aligned and attached to the upper surface of the second outer mold, then stacking the second to-be-bonded framework on the second skin, finally aligning the elastic layer of the second cover plate to the second surface of the first skin for buckling, and fixing the second side baffle plates and the second cover plate to obtain a second assembled mold;
10) and curing the second assembly mold to complete bonding, so as to obtain a final product.
In an optional embodiment, in the step 1), the external form die and the side baffle are made of steel; the elastic layer is made of silicon rubber; the cover plate is made of steel or composite materials.
In an optional embodiment, the mass of the resin glue solution in the hot-melt prepreg in the step 2) accounts for 36-42% of the total mass of the hot-melt prepreg.
In an optional embodiment, the adhesive film in step 3) is an epoxy adhesive film or a bismaleimide adhesive film.
In an alternative embodiment, the number of prepreg layup layers in step 4) is 1-5.
In an alternative embodiment, the curing the first assembling mold in the step 6) includes:
and filling the first assembly mold into a vacuum bag, vacuumizing, maintaining the pressure for more than 0.5h, introducing atmospheric air into the vacuum bag before curing, and curing under the pressure of 0.01-0.05 MPa.
In an optional embodiment, in the step 6), when the resin glue solution in the hot-melt prepreg is an epoxy resin system, the curing temperature is 160-180 ℃, and the heat preservation time is 1-2 h; when the resin glue solution in the hot-melt prepreg is a bismaleimide resin system, the curing temperature is 190-200 ℃, and the heat preservation time is 2-4 h.
In an alternative embodiment, said curing said second assembly mold in step 10) includes:
and filling the second assembly mold into a vacuum bag, vacuumizing, maintaining the pressure for more than 0.5h, introducing atmospheric air into the vacuum bag before curing, and curing under the pressure of 0.01-0.05 MPa.
In an optional embodiment, in the step 10), when the resin glue solution in the hot-melt prepreg is an epoxy resin system, the curing temperature is 160-180 ℃, and the heat preservation time is 2-4 h; when the resin glue solution in the hot-melt prepreg is a bismaleimide resin system, the curing temperature is 190-200 ℃, and the heat preservation time is 6-12 h.
The utility model provides a bonding mould for bonding thickness-variable composite material skeleton and covering, includes first outline mould, first side shield and first apron, the interior profile of first apron with the first surface of skeleton matches and is equipped with the elastic layer, the upper surface of first outline mould with the second surface of covering matches, the first surface with the second surface orientation is opposite, first side shield centers on first outline mould and first apron set up, are used for making form between first outline mould and the first apron the die cavity of skeleton and covering bonding piece.
In an optional embodiment, the skin includes a first skin and a second skin respectively located on two sides of the framework, an upper surface of the first outer mold is matched with a second surface of the first skin, the bonding mold further includes a second outer mold, a second side baffle and a second cover plate, an inner molding surface of the second cover plate is matched with the second surface of the first skin and provided with an elastic layer, and an upper surface of the second outer mold is consistent with the first surface of the second skin.
Compared with the prior art, the invention has the following beneficial effects:
(1) according to the bonding method provided by the embodiment of the invention, the cavity of the frame and skin bonding part is formed by arranging the outline die, the cover plate and the side baffle, so that the skin and the frame are ensured to be positioned accurately, the surface of the outline die and the cover plate in the cavity restrains the molded surfaces of the frame and the skin, and the elastic layer is arranged on the cover plate to effectively adjust the bonding gap between the contact surfaces of the outline die and the cover plate, so that effective contact is ensured, the bonding quality is improved, the problems of debonding of the contact surfaces and over-tolerance of the outline size caused by deformation of the frame and the skin are avoided, and the requirement on pneumatic appearance is effectively ensured; by laying hot-melt prepreg on the interface and controlling curing molding, the interface bonding quality and the overall dimension precision are further improved;
(2) the double-curvature skeleton skin structure has good interface bonding quality and outline dimension precision, and the structural dimension can reach 2000mm magnitude.
Drawings
FIG. 1 is a schematic structural view of a variable thickness composite carcass and skin;
FIG. 2 is a schematic view of an assembly of a bonding mold and a skeleton skin structure according to an embodiment of the present invention;
FIG. 3 is a process flow diagram of an embodiment of the invention;
FIG. 4 is a schematic view of a skeletal skin structure provided in example 2 of the present invention;
fig. 5 is a schematic view of a skeleton skin structure provided in embodiment 3 of the present invention.
Detailed Description
The invention is further illustrated by the following figures and examples.
As shown in fig. 2, an embodiment of the present invention provides a bonding mold for bonding a variable thickness composite material skeleton 100 and a lower skin 200 located on a lower side of the skeleton, the bonding mold includes a first outer mold 10, a first side barrier 20 and a first cover plate 30, an inner surface of the first cover plate 30 matches with an upper surface of the skeleton and is provided with an elastic layer, an upper surface of the first outer mold 10 matches with a lower surface of the lower skin 200, and the first side barrier 20 is disposed around the first outer mold 10 and the first cover plate 30, so as to form a cavity for bonding the skeleton 100 and the skin between the first outer mold 10 and the first cover plate.
According to the bonding die provided by the embodiment of the invention, the cavity of the frame and the skin bonding part is formed by arranging the outline die, the cover plate and the side baffle, so that the skin and the frame are ensured to be positioned accurately, the molded surfaces of the frame and the skin are restrained by the surfaces of the outline die and the cover plate positioned in the cavity, the bonding gap between the contact surfaces of the outline die and the cover plate is effectively adjusted by arranging the elastic layer on the cover plate, so that effective contact is ensured, the bonding quality is improved, the problems of contact surface debonding and appearance size over-tolerance caused by deformation of the frame and the skin are avoided, and the requirement on pneumatic appearance is effectively ensured.
The bonding mold provided by the embodiment of the invention further comprises a second outer mold, a second side baffle and a second cover plate, wherein the second outer mold, the second side baffle and the second cover plate are used for bonding the variable-thickness composite material framework 100 and the upper skin 300 positioned on the upper side of the framework, the inner profile of the second cover plate is matched with the lower surface of the lower skin 200 and is provided with an elastic layer, the upper surface of the second outer mold is consistent with the upper surface of the upper skin 300, and the second side baffle is used for enabling a cavity of a bonding piece of the framework 100, the lower skin 200 and the upper skin 300 to be formed between the second outer mold and the second cover. The die can realize the bonding of two layers of skins, and effectively ensures the requirement of pneumatic appearance.
In the embodiment of the invention, the external form die and the side baffle are preferably made of steel; the elastic layer is preferably made of silicon rubber, and the cover plate is preferably made of steel or composite materials. Through the mixed use of different materials of different positions, the rigidity requirement of the mould and the pressure distribution adjustment of the height position of the product are effectively ensured.
The embodiment of the invention also provides a method for bonding the variable-thickness composite material skeleton and the skin, which is used for bonding the variable-thickness composite material skeleton 100 and the lower skin 200 positioned on the lower side of the skeleton, and the method comprises the following steps:
1) preparing a bonding mold, wherein the bonding mold comprises a first outer mold 10, a first side baffle 20 and a first cover plate 30, the inner molded surface of the first cover plate 30 is matched with the upper surface of the framework and is provided with an elastic layer, the upper surface of the first outer mold 10 is matched with the lower surface of the lower skin 200, and the first side baffle 20 is arranged around the first outer mold 10 and the first cover plate 30 and is used for forming a cavity of the framework 100 and the skin bonding piece between the first outer mold 10 and the first cover plate;
2) dipping the carbon fiber cloth reinforcement into resin glue solution to prepare hot-melt prepreg;
specifically, the resin glue solution is preferably an epoxy resin system or a bismaleimide resin system;
3) after the lower surface of the framework 100 and the upper surface of the lower skin 200 are processed, respectively sticking a layer of adhesive film;
4) paving the surface of an adhesive film on the framework 100 by adopting the hot-melt prepreg to obtain a first framework to be bonded;
5) arranging first side baffles 20 around the first outline mold 10 to form a cavity of a framework and skin bonding piece, putting a lower skin 200 into the cavity, enabling the lower surface of the lower skin 200 to be aligned and attached to the upper surface of the first outline mold 10, stacking the first to-be-bonded framework on the lower skin 200, aligning the elastic layer of a first cover plate 30 to the upper surface of the framework 100, and fastening the first side baffles 20 and the first cover plate 30 to obtain a first assembled mold;
6) and curing the first assembling die to finish bonding.
The bonding mold used in this embodiment is provided by the above mold embodiment, and for specific description, reference is made to the above mold embodiment, which is not described herein again.
In an optional embodiment, the bonding mold further comprises a second outer mold, a second side baffle and a second cover plate, the second outer mold is used for bonding the variable-thickness composite material skeleton 100 and the upper skin 300 located on the upper side of the skeleton 100, an inner profile of the second cover plate is matched with the lower surface of the lower skin 200 and is provided with an elastic layer, the upper surface of the second outer mold is consistent with the upper surface of the upper skin 300, the second side baffle is used for enabling a cavity of a bonding piece of the skeleton 100, the lower skin 200 and the upper skin 300 to be formed between the second outer mold and the second cover plate, and the bonding of the skeleton 100 and the lower skin 200 is realized according to the steps 1) -6), so that a semi-finished product is obtained; then carrying out the following steps:
7) after the upper surface of the framework 100 and the lower surface of the upper skin 300 are processed, respectively sticking a layer of adhesive film;
8) paving the adhesive film surface on the first surface of the framework 100 by adopting the hot-melt prepreg to obtain a second framework to be bonded;
9) arranging the second side baffle plates around the second outer mold to form a cavity of a bonding piece of the framework 100, the upper skin 300 and the lower skin 200, putting the upper skin 300 into the cavity to enable the upper surface of the upper skin 300 to be aligned and attached to the upper surface of the second outer mold, stacking the second to-be-bonded framework on the upper skin 300, aligning the elastic layer of the second cover plate to the upper surface of the lower skin for buckling, and fixing the second side baffle plates and the second cover plate to obtain a second assembly mold;
10) and curing the second assembly mold to complete bonding, so as to obtain a final product.
According to the bonding method provided by the embodiment of the invention, the cavity of the frame and skin bonding part is formed by arranging the outline die, the cover plate and the side baffle, so that the skin and the frame are ensured to be positioned accurately, the surface of the outline die and the cover plate in the cavity restrains the molded surfaces of the frame and the skin, and the elastic layer is arranged on the cover plate to effectively adjust the bonding gap between the contact surfaces of the outline die and the cover plate, so that effective contact is ensured, the bonding quality is improved, the problems of debonding of the contact surfaces and over-tolerance of the outline size caused by deformation of the frame and the skin are avoided, and the requirement on pneumatic appearance is effectively ensured; by laying hot-melt prepreg on the interface and controlling curing molding process parameters, the interface bonding quality and the overall dimension precision are further improved.
In an optional embodiment, in the step 1), the external form die and the side baffle are made of steel; the elastic layer is made of silicon rubber, and the cover plate is made of steel or a composite material. Through the mixed use of different materials of different positions, the rigidity requirement of the mould and the pressure distribution adjustment of the height position of the product are effectively ensured.
In an optional embodiment, the mass of the resin glue solution in the hot-melt prepreg in the step 2) accounts for 36-42% of the total mass of the hot-melt prepreg. The product performance requirements of the final product are effectively ensured by controlling the resin glue solution content in the prepreg.
In an optional embodiment, the adhesive film in step 3) is an epoxy adhesive film or a bismaleimide adhesive film matched with the skeleton and skin material system. The final temperature-resistant grade and performance matching of the product are ensured through effective matching of materials.
In an alternative embodiment, the number of prepreg layup layers in step 4) is 1-5. When the thickness of the layer is laid, the gap between the skin and the framework can be effectively adjusted, the bonding quality is ensured, the local debonding is further avoided, and the molded surface precision of the final product is ensured.
In an alternative embodiment, the curing the first assembling mold in the step 6) includes:
and filling the first assembly mold into a vacuum bag, vacuumizing, maintaining the pressure for more than 0.5h, introducing atmospheric air into the vacuum bag before curing, and curing under the pressure of 0.01-0.05 MPa. Through vacuum and pressure control, the interface bonding quality of the skin skeleton is effectively guaranteed, and meanwhile, the quality of the skin body is guaranteed.
In an optional embodiment, in the step 6), when the resin glue solution in the hot-melt prepreg is an epoxy resin system, the curing temperature is 160-180 ℃, and the heat preservation time is 1-2 h; when the resin glue solution in the hot-melt prepreg is a bismaleimide resin system, the curing temperature is 190-200 ℃, and the heat preservation time is 2-4 h. By controlling the curing process parameters, the interface bonding performance is ensured to meet the use requirement at room temperature.
In an alternative embodiment, said curing said second assembly mold in step 10) includes:
and filling the second assembly mold into a vacuum bag, vacuumizing, maintaining the pressure for more than 0.5h, introducing atmospheric air into the vacuum bag before curing, and curing under the pressure of 0.01-0.05 MPa. By vacuum and pressure control, the interface bonding quality of the skin and the framework is effectively ensured, and the skin, the framework and the overall quality are ensured.
In an optional embodiment, in the step 10), when the resin glue solution in the hot-melt prepreg is an epoxy resin system, the curing temperature is 160-180 ℃, and the heat preservation time is 2-4 h; when the resin glue solution in the hot-melt prepreg is a bismaleimide resin system, the curing temperature is 190-200 ℃, and the heat preservation time is 6-12 h. By controlling the curing process parameters, the interface bonding performance is ensured to meet the design and use requirements.
The following are several specific embodiments of the invention:
example 1
As shown in fig. 1, the present embodiment provides a composite material skeleton skin structure for an aircraft wing, which includes an integral skeleton 100, an upper skin 300, and a lower skin 200, where the skeleton structure is composed of an upper frame, a lower frame, and a plurality of sets of vertical plates 3 with different heights, where the upper frame is formed by a plurality of first frame strips 11 to form a multi-lattice structure, the lower frame is formed by a plurality of second frame strips 22 to form a multi-lattice structure, the first frame strips 11 and the second frame strips 21 are in one-to-one correspondence, a vertical plate 3 is disposed between the corresponding first frame strips 11 and the corresponding second frame strips 21, and a vertical section is formed as a structure with an i-shaped vertical section, an upper surface of the upper frame and a lower surface of the lower frame are both hyperbolic curved surfaces, and accordingly, the upper skin 300 and the lower skin 200 are both made of a carbon fiber reinforced bismaleimide-based composite material, and the skeleton skin structure has a maximum length of 2170mm, a maximum, the minimum height is 85 mm; the width of the frame strip is 60mm-80 mm.
As shown in fig. 3, the method for bonding the frame and the skin of the composite material frame skin structure of the embodiment includes the following steps:
1) manufacturing a bonding mold; the bonding mold comprises a first bonding mold and a second bonding mold, the first bonding mold comprises a first outer mold 10, a first side baffle 20 and a first cover plate 30, the second bonding mold comprises a second outer mold, a second side baffle and a second cover plate, the inner profile surface of the first cover plate 30 is matched with the upper surface of the framework 100 and is provided with an elastic layer, the upper surface of the first outer mold 10 is matched with the lower surface of the lower skin 200, the first side baffle 20 is arranged around the first outer mold 10 and the first cover plate 30 and is used for enabling the first outer mold 10 and the first cover plate to form a cavity of the framework 100 and the skin bonding piece, the inner profile surface of the second cover plate is matched with the lower surface of the lower skin 200 and is provided with an elastic layer, the upper surface of the second outer mold is consistent with the upper surface of the upper skin 300, and the second side baffle is used for enabling the second outer mold and the second cover plate to form a framework 100, a first side baffle 30 and a second cover plate, A cavity for bonding pieces of the lower skin 200 and the upper skin 300; wherein the external form die and the side baffle are made of steel; the elastic layer is made of silicon rubber, and the cover plate is made of steel;
2) soaking a carbon fiber cloth reinforcing material into bismaleimide resin glue solution to prepare a hot-melt prepreg; the mass of the resin glue solution in the hot-melt prepreg accounts for 40 +/-2% of the mass of the hot-melt prepreg, and the hot-melt prepreg is preparedThe thickness of the hot-melt prepreg (2) was 0.2mm, and the surface density was 210g/m2。
3) Performing interface treatment on the upper surface of the framework and the lower surface of the upper skin, and then respectively sticking a layer of bismaleimide film;
4) cutting the prepared hot-melt prepreg into a size of a framework bonding interface layer spread, and performing layer spreading and stacking on the surface of a glue film of the framework according to the layer spreading sequence of the framework and skin interface design to obtain a first framework to be bonded; the designed spreading sequence is the stacking sequence of the hot-melt prepreg, and the number of layers is 5.
5) Sequentially assembling a second outer die and a second side baffle in a second bonding die, placing the upper skin in the step 3) and the bonding framework in the step 4), and finally placing a second cover plate;
6) curing the assembled mould obtained in the step 5) to obtain a cured upper skin assembly of the framework;
the curing is carried out in an autoclave, and the curing process comprises the following steps: the vacuum bag pressure is 0 MPa; the pressure is 0.02 MPa; the heating rate is 25 plus or minus 5 ℃/h, the heat preservation temperature is 190-195 ℃, the heat preservation time is 2h, the temperature is reduced to the room temperature along with the furnace, and the curing is finished.
7) And (4) removing the assembly mold of the skin assembly on the framework cured in the step 6) to obtain a semi-finished product.
8) Bonding the framework and the lower skin by adopting a first bonding mold according to the steps 3) to 5) to obtain an assembly mold;
9) curing the assembled mould obtained in the step 8) to obtain a cured product;
the curing is carried out in an autoclave, and the curing process comprises the following steps: the vacuum bag pressure is 0 MPa; the pressure is 0.02 MPa; the heating rate is 25 plus or minus 5 ℃/h, the heat preservation temperature is 190-195 ℃, the heat preservation time is 12h, the temperature is reduced to the room temperature along with the furnace, and the curing is finished.
10) And removing the assembly mold of the product solidified in the step 9) to obtain the product.
The overall dimension of the carbon fiber reinforced bismaleimide resin based composite double-curvature skeleton skin structure product prepared by the embodiment meets the design requirement, the interfacial adhesion debonding area is 0.23%, the design requirement that the defect area is not more than 1% of the total area is met, and finally the molding quality and the dimensional accuracy requirement of the double-curvature skeleton skin structure product are ensured.
Example 2
As shown in fig. 4, the present embodiment provides a composite material skeleton skin structure for an aircraft empennage, which includes an integral skeleton 100, an upper skin 300, and a lower skin 200, where the skeleton structure is composed of an upper frame, a lower frame, and a plurality of sets of vertical plates 3 with different heights, where the upper frame is formed by a plurality of first frame strips 11 to form a multi-lattice structure, the lower frame is formed by a plurality of second frame strips 22 to form a multi-lattice structure, the first frame strips 11 and the second frame strips 21 are in one-to-one correspondence, a vertical plate 3 is disposed between the corresponding first frame strips 11 and the corresponding second frame strips 21, and forms a structure with an i-shaped vertical cross section, an upper surface of the upper frame and a lower surface of the lower frame are both hyperbolic curved surfaces, and accordingly, the upper skin 300 and the lower skin 200 are both made of a carbon fiber reinforced epoxy resin-based composite material, and have a maximum length of 2190mm, a maximum width of 750mm, the minimum height is 26 mm; the width of the frame strip is 30mm-60 mm.
As shown in fig. 3, the method for bonding the frame and the skin of the composite material frame skin structure of the embodiment includes the following steps:
1) manufacturing a bonding mold; the bonding mold comprises a first bonding mold and a second bonding mold, the first bonding mold comprises a first outer mold 10, a first side baffle 20 and a first cover plate 30, the second bonding mold comprises a second outer mold, a second side baffle and a second cover plate, the inner profile surface of the first cover plate 30 is matched with the upper surface of the framework 100 and is provided with an elastic layer, the upper surface of the first outer mold 10 is matched with the lower surface of the lower skin 200, the first side baffle 20 is arranged around the first outer mold 10 and the first cover plate 30 and is used for enabling the first outer mold 10 and the first cover plate to form a cavity of the framework 100 and the skin bonding piece, the inner profile surface of the second cover plate is matched with the lower surface of the lower skin 200 and is provided with an elastic layer, the upper surface of the second outer mold is consistent with the upper surface of the upper skin 300, and the second side baffle is used for enabling the second outer mold and the second cover plate to form a framework 100, a first side baffle 30 and a second cover plate, A cavity for bonding pieces of the lower skin 200 and the upper skin 300; wherein the external form die and the side baffle are made of steel; the elastic layer is made of silicon rubber, and the cover plate is made of composite material;
2) soaking a carbon fiber cloth reinforcing material into an epoxy resin glue solution to prepare a hot-melt prepreg; the mass of the resin glue solution in the hot-melt prepreg accounts for 38 +/-2% of the mass of the hot-melt prepreg, the thickness of the prepared hot-melt prepreg is 0.2mm, and the surface density is 210g/m2。
3) Performing interface treatment on the upper surface of the framework and the lower surface of the upper skin, and then respectively sticking a layer of epoxy adhesive film;
4) cutting the prepared hot-melt prepreg into a size of a framework bonding interface layer spread, and performing layer spreading and stacking on the surface of a glue film of the framework according to the layer spreading sequence of the framework and skin interface design to obtain a first framework to be bonded; the designed spreading sequence is the stacking sequence of the hot-melt prepreg, and the number of layers is 1.
5) Sequentially assembling a second outer die and a second side baffle in a second bonding die, placing the upper skin in the step 3) and the bonding framework in the step 4), and finally placing a second cover plate;
6) curing the assembled mould obtained in the step 5) to obtain a cured upper skin assembly of the framework;
the curing is carried out in an autoclave, and the curing process comprises the following steps: the vacuum bag pressure is 0 MPa; the pressure is 0.03 MPa; the heating rate is 25 plus or minus 5 ℃/h, the heat preservation temperature is 170 plus or minus 5 ℃, the heat preservation time is 1h, the temperature is reduced to the room temperature along with the furnace, and the curing is finished.
7) And (4) removing the assembly mold of the skin assembly on the framework cured in the step 6) to obtain a semi-finished product.
8) Bonding the framework and the lower skin by adopting a first bonding mold according to the steps 3) to 5) to obtain an assembly mold;
9) curing the assembled mould obtained in the step 8) to obtain a cured product;
the curing is carried out in an autoclave, and the curing process comprises the following steps: the vacuum bag pressure is 0 MPa; the pressure is 0.03 MPa; the heating rate is 25 +/-5 ℃/h, the heat preservation temperature is 170 +/-5 ℃, the heat preservation time is 3h, the temperature is reduced to the room temperature along with the furnace, and the curing is finished.
10) And removing the assembly mold of the product solidified in the step 9) to obtain the product.
The overall dimension of the carbon fiber reinforced epoxy resin matrix composite double-curvature skeleton skin structure product prepared by the embodiment meets the design requirement, the interfacial adhesion debonding area is 0.06%, the design requirement that the defect area is not more than 1% of the total area is met, and finally the molding quality and the dimensional accuracy requirement of the double-curvature skeleton skin structure product are ensured.
Example 3
As shown in fig. 5, the present embodiment provides a composite material skeleton skin structure of an aircraft wing test piece, which includes an integral skeleton 100, an upper skin 300, and a lower skin 200, where the skeleton structure is composed of an upper frame, a lower frame, and a plurality of sets of vertical plates 3 with different heights, where the upper frame is formed by a plurality of first frame strips 11 to form a multi-lattice structure, the lower frame is formed by a plurality of second frame strips 22 to form a multi-lattice structure, the first frame strips 11 and the second frame strips 21 are in one-to-one correspondence, a vertical plate 3 is disposed between the corresponding first frame strips 11 and the corresponding second frame strips 21, and forms a structure with an i-shaped vertical section, an upper surface of the upper frame and a lower surface of the lower frame are both hyperbolic curved surfaces, and accordingly, the upper skin 300 and the lower skin 200 are both hyperbolic curved surfaces, the skeleton skin structure is made of a carbon fiber reinforced bismaleimide-based composite material, and has a maximum length of 815mm, the minimum height is 90 mm; the width of the frame strip is 60mm-75 mm.
As shown in fig. 3, the method for bonding the frame and the skin of the composite material frame skin structure of the embodiment includes the following steps:
1) preparing a bonding mold; the bonding mold comprises a first bonding mold and a second bonding mold, the first bonding mold comprises a first outer mold 10, a first side baffle 20 and a first cover plate 30, the second bonding mold comprises a second outer mold, a second side baffle and a second cover plate, the inner profile surface of the first cover plate 30 is matched with the upper surface of the framework 100 and is provided with an elastic layer, the upper surface of the first outer mold 10 is matched with the lower surface of the lower skin 200, the first side baffle 20 is arranged around the first outer mold 10 and the first cover plate 30 and is used for enabling the first outer mold 10 and the first cover plate to form a cavity of the framework 100 and the skin bonding piece, the inner profile surface of the second cover plate is matched with the lower surface of the lower skin 200 and is provided with an elastic layer, the upper surface of the second outer mold is consistent with the upper surface of the upper skin 300, and the second side baffle is used for enabling the second outer mold and the second cover plate to form a framework 100, a first side baffle 30 and a second cover plate, A cavity for bonding pieces of the lower skin 200 and the upper skin 300; wherein the external form die and the side baffle are made of steel; the elastic layer is made of silicon rubber, and the cover plate is made of steel;
2) soaking a carbon fiber cloth reinforcing material into bismaleimide resin glue solution to prepare a hot-melt prepreg; the mass of the resin glue solution in the hot-melt prepreg accounts for 40 +/-2% of the mass of the hot-melt prepreg, the thickness of the prepared hot-melt prepreg is 0.2mm, and the surface density is 210g/m2。
3) Performing interface treatment on the upper surface of the framework and the lower surface of the upper skin, and then respectively sticking a layer of bismaleimide film;
4) cutting the prepared hot-melt prepreg into a size of a framework bonding interface layer spread, and performing layer spreading and stacking on the surface of a glue film of the framework according to the layer spreading sequence of the framework and skin interface design to obtain a first framework to be bonded; the designed spreading sequence is the stacking sequence of the hot-melt prepreg, and the number of layers is 3.
5) Sequentially assembling a second outer die and a second side baffle in a second bonding die, placing the upper skin in the step 3) and the bonding framework in the step 4), and finally placing a second cover plate;
6) curing the assembled mould obtained in the step 5) to obtain a cured upper skin assembly of the framework;
the curing is carried out in an autoclave, and the curing process comprises the following steps: the vacuum bag pressure is 0 MPa; the pressure is 0.03 MPa; the heating rate is 25 plus or minus 5 ℃/h, the heat preservation temperature is 190-195 ℃, the heat preservation time is 2h, the temperature is reduced to the room temperature along with the furnace, and the curing is finished.
7) And (4) removing the assembly mold of the skin assembly on the framework cured in the step 6) to obtain a semi-finished product.
8) Bonding the framework and the lower skin by adopting a first bonding mold according to the steps 3) to 5) to obtain an assembly mold;
9) curing the assembled mould obtained in the step 8) to obtain a cured product;
the curing is carried out in an autoclave, and the curing process comprises the following steps: the vacuum bag pressure is 0 MPa; the pressure is 0.03 MPa; the heating rate is 25 plus or minus 5 ℃/h, the heat preservation temperature is 190-195 ℃, the heat preservation time is 12h, the temperature is reduced to the room temperature along with the furnace, and the curing is finished.
10) And removing the assembly mold of the product solidified in the step 9) to obtain the product.
The overall dimension of the carbon fiber reinforced bismaleimide resin based composite double-curvature skeleton skin structure product prepared by the embodiment meets the design requirement, the interfacial adhesion debonding is not detected, the design requirement that the defect area is not more than 1% of the total area is met, and finally the molding quality and the dimensional accuracy requirement of the double-curvature skeleton skin structure product are ensured.
The foregoing is only a few embodiments of the present invention. It should be noted that variations and modifications can be made by those skilled in the art without departing from the principle of the present invention, and they should also be considered as falling within the scope of the present invention.
The invention has not been described in detail in part of the common general knowledge of those skilled in the art.
Claims (12)
1. A method for bonding a variable-thickness composite material framework and a skin is characterized by comprising the following steps:
1) preparing a bonding mold, wherein the bonding mold comprises a first outer mold, a first side baffle and a first cover plate, the inner profile surface of the first cover plate is matched with the first surface of the framework and is provided with an elastic layer, and the upper surface of the first outer mold is matched with the second surface of the skin; the first side baffle is arranged around the first outer mould and the first cover plate and is used for forming a cavity of the framework and skin bonding piece between the first outer mould and the first cover plate;
2) dipping the carbon fiber cloth reinforcement into resin glue solution to prepare hot-melt prepreg;
3) after the second surface of the framework and the first surface of the skin are processed, respectively sticking a layer of adhesive film, wherein the first surface of the skin and the second surface of the framework face opposite directions;
4) paving the surface of an adhesive film on the framework by adopting the hot-melt prepreg to obtain a first framework to be bonded;
5) arranging the first side baffle plates around the first outline mold to form a cavity of a framework and skin bonding piece, placing the skin into the cavity, aligning and attaching the second surface of the skin to the upper surface of the first outline mold, stacking the first to-be-bonded framework on the skin, aligning the elastic layer of the first cover plate to the first surface of the framework, and fastening the first side baffle plates and the first cover plate to obtain a first assembly mold; the first side baffle and the bonding piece in the cavity are arranged separately;
6) and curing the first assembling die to finish bonding.
2. The method of claim 1, wherein the skin comprises a first skin and a second skin respectively disposed on two sides of the frame, an upper surface of the first outer mold is matched with a second surface of the first skin, the bonding mold further comprises a second outer mold, a second side baffle and a second cover plate, an inner surface of the second cover plate is matched with the second surface of the first skin and is provided with an elastic layer, and an upper surface of the second outer mold is matched with the first surface of the second skin, the bonding method comprises:
bonding the framework and the first skin according to the steps 1) to 6) to obtain a semi-finished product;
then carrying out the following steps:
7) after the first surface of the framework and the second surface of the second skin are processed, respectively pasting a layer of adhesive film;
8) paving the adhesive film surface on the first surface of the framework by adopting the hot-melt prepreg to obtain a second framework to be bonded;
9) arranging the second side baffle plates around the second outer mold to form a cavity of a framework, a first skin and a second skin bonding piece, placing the second skin into the cavity to enable the first surface of the second skin to be aligned and attached to the upper surface of the second outer mold, then stacking the second to-be-bonded framework on the second skin, finally aligning the elastic layer of the second cover plate to the second surface of the first skin for buckling, and fixing the second side baffle plates and the second cover plate to obtain a second assembled mold; the second side baffle and the bonding piece in the cavity are arranged separately;
10) and curing the second assembly mold to complete bonding, so as to obtain a final product.
3. The method for bonding the variable-thickness composite material skeleton and the skin according to claim 1, wherein in the step 1), the external mold and the side baffle are made of steel; the elastic layer is made of silicon rubber; the cover plate is made of steel or composite materials.
4. The method for bonding the variable-thickness composite material skeleton and the skin according to claim 1, wherein the mass of the resin glue solution in the hot-melt prepreg in the step 2) accounts for 36-42% of the total mass of the hot-melt prepreg.
5. The method for bonding the variable-thickness composite material skeleton and the skin according to claim 1, wherein the adhesive film in the step 3) is an epoxy adhesive film or a bismaleimide adhesive film.
6. The method for bonding the variable thickness composite material skeleton and the skin according to claim 1, wherein the number of prepreg laying layers in the step 4) is 1-5.
7. The method for bonding a variable thickness composite skeleton to a skin according to claim 1 or 2, wherein the step 6) of curing the first assembling mold comprises:
and filling the first assembly mold into a vacuum bag, vacuumizing, maintaining the pressure for more than 0.5h, introducing atmospheric air into the vacuum bag before curing, and curing under the pressure of 0.01-0.05 MPa.
8. The method for bonding the variable-thickness composite material skeleton and the skin according to claim 7, wherein in the step 6), when the resin glue solution in the hot-melt prepreg is an epoxy resin system, the curing temperature is 160-180 ℃, and the heat preservation time is 1-2 h; when the resin glue solution in the hot-melt prepreg is a bismaleimide resin system, the curing temperature is 190-200 ℃, and the heat preservation time is 2-4 h.
9. The method of claim 2, wherein the curing the second assembly mold in step 10) comprises:
and filling the second assembly mold into a vacuum bag, vacuumizing, maintaining the pressure for more than 0.5h, introducing atmospheric air into the vacuum bag before curing, and curing under the pressure of 0.01-0.05 MPa.
10. The method for bonding the variable-thickness composite material skeleton and the skin according to claim 9, wherein in the step 10), when the resin glue solution in the hot-melt prepreg is an epoxy resin system, the curing temperature is 160-180 ℃, and the heat preservation time is 2-4 h; when the resin glue solution in the hot-melt prepreg is a bismaleimide resin system, the curing temperature is 190-200 ℃, and the heat preservation time is 6-12 h.
11. A bonding die for implementing the method for bonding the framework and the skin of the variable-thickness composite material according to claim 1, which comprises a first outer die, a first side baffle and a first cover plate, wherein the inner profile surface of the first cover plate is matched with the first surface of the framework and is provided with an elastic layer, the upper surface of the first outer die is matched with the second surface of the skin, the first surface and the second surface face opposite, and the first side baffle is arranged around the first outer die and the first cover plate and is used for forming a cavity of the framework-skin bonding piece between the first outer die and the first cover plate.
12. The bonding die of claim 11, wherein: the covering is including being located respectively the first covering and the second covering of skeleton both sides, the upper surface of first outline mould with the second surface of first covering matches, the bonding mould still includes second outline mould, second side shield and second apron, the interior profile of second apron with first covering second surface matches and is equipped with the elastic layer, the upper surface of second outline mould with the first surface of second covering is unanimous.
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