Composite material integrated forming process based on variable-thickness honeycomb bidirectional splicing

Abstract

The invention discloses a composite material integrated forming process based on variable-thickness honeycomb bidirectional splicing. The process has the advantages of being high in operability, flexible in designability and the like. The process of honeycomb splicing and positioning, forming of the upper panel and the lower panel of the carbon fiber composite material and the like can be completed through one mold with multiple purposes, and manufacturing manpower, material resources and time cost are reduced; honeycomb two-way splicing and carbon fiber prepreg integrated forming can also be achieved, the large-size honeycomb sandwich structure forming technology is defined, and the product quality and the size precision are guaranteed. Meanwhile, in order to guarantee the surface quality of the product, local stabilization of the honeycomb splicing seam chamfering area and honeycomb splicing can be synchronously carried out, and the method can be used for subsequent ultra-large full-size honeycomb sandwich structure product manufacturing.

Description

Technical Field

[0001] The invention relates to the technical field of composite honeycomb sandwich component forming, and in particular to an integrated composite material forming process based on two-way splicing of variable thickness honeycombs. Background Art

[0002] Composite honeycomb sandwich structures are composed of two thin skins with a lightweight core material sandwiched between them. Due to its excellent properties such as high specific modulus, high specific strength and light weight, this structure is widely used in aerospace and other cutting-edge technology fields.

[0003] At present, honeycombs are mainly used as core materials for large-size and variable-thickness composite sandwich structures due to their advantages in environmental protection, pressure bearing, and designability. To ensure the molding quality of the structure, the current manufacturing process usually involves first splicing the honeycombs, and then embedding the spliced ​​honeycombs into composite carbon fiber panel prepreg for molding.

[0004] However, most of the existing honeycomb splicing methods are single-direction splicing (such as L-direction or W-direction) or two-way splicing followed by product manufacturing, and rarely involve the process of two-way splicing of honeycombs and integrated molding of composite materials.

[0005] In order to solve the above problems, it is urgent to develop an integrated molding process for composite materials with variable thickness honeycomb bidirectional splicing. Summary of the invention

[0006] In view of the problems that the existing honeycombs can only be spliced ​​in a single direction and the honeycomb splicing and composite materials cannot be integrated into one molding, the present invention provides a composite material integrated molding process based on the two-way splicing of variable thickness honeycombs, which can achieve multiple uses of one mold to complete the two-way splicing and positioning of the honeycomb and the prepreg molding of the inner and outer panels of the carbon fiber composite materials, thereby reducing the manufacturing cost, clarifying the molding process of the large-size honeycomb sandwich structure, and ensuring the product quality and dimensional accuracy.

[0007] In order to solve the above technical problems, the present invention provides an integrated molding process of composite materials based on variable thickness honeycomb bidirectional splicing, comprising the following steps: Step A: Prefabricate honeycombs. Multiple honeycomb raw materials with different heights and excess are machined into net-size honeycombs with gradient thickness by a five-axis machine tool, and then dried for use. Step B: Arrange in L direction, put the dried net size honeycomb into the forming tooling, and arrange it according to the size and outline of the product part; Step C: L-direction splicing: placing adhesive on the surface of the net-size honeycomb to be spliced, and completing the L-direction splicing of all net-size honeycombs in sequence; Step D: Local stabilization of the chamfered area of ​​the honeycomb joint, local stabilization of the chamfered area of ​​the net-size honeycomb after L-direction splicing, the chamfered area of ​​the joint is located at the chamfered joint of the net-size honeycomb spliced ​​in the L direction at the outermost ends; specifically, a layer of adhesive film is laid on the upper and lower chamfered areas of the joint, and after the adhesive film is laid, a dry peelable cloth, an isolation film and a glass fiber board are placed in the chamfered areas in sequence, and finally a breathable felt and a vacuum bag are used for packaging, and then cured to form a plurality of L-direction spliced ​​honeycombs; a plurality of L-direction spliced ​​honeycombs are formed; Step E: Laying the composite material lower panel prepreg, laying the lower panel prepreg on the forming tooling, and laying the adhesive film for bonding the honeycomb at the same time; Step F: Arrange in W direction, place a layer of isolation film on the lower panel prepreg, and pre-position multiple L-direction spliced ​​honeycombs on the isolation film according to the size and contour of the product part; Step G: W-direction splicing: placing adhesive on the surface to be spliced ​​of the L-direction spliced ​​honeycombs, and sequentially completing the W-direction splicing of all the L-direction spliced ​​honeycombs; thereby forming a spliced ​​honeycomb core; Step H: Positioning the spliced ​​honeycomb core, lift one side of the spliced ​​honeycomb core, slowly pull out the isolation film, and use a laser projector to position the spliced ​​honeycomb core after the isolation film is completely pulled out, so as to adjust the position of the spliced ​​honeycomb core until the spliced ​​honeycomb core is completely within the projection line; Step I: Laying the composite material upper panel prepreg, laying the adhesive film again on the spliced ​​honeycomb core, and laying the upper panel prepreg on the adhesive film; Step J: Packaging: When packaging the product, in order to achieve equal pressure in the local stabilization area of ​​the film, a glass fiber board with a gradient thickness is placed, and the glass fiber board with a gradient thickness is placed between the second isolation film of the packaging and the breathable felt; Step K: Product bagging and curing: Put the packaged product into a vacuum bag for curing.

[0008] Preferably, the net-size honeycomb is an aramid paper honeycomb with a gradient thickness, the honeycomb thickness is 15-30 mm, and the honeycomb angle is 5-15°.

[0009] Preferably, the net-size honeycomb needs to be dried after mechanical processing, specifically: dried at 120±8° C. for more than 60 minutes or dried at 60±8° C. for more than 120 minutes.

[0010] Preferably, step C and step D, L-direction splicing and local stabilization of the honeycomb seam chamfering area are cured at one time and completed simultaneously.

[0011] Preferably, in step D, a layer of adhesive film is laid on the upper and lower chamfered areas of the joint, specifically: the adhesive film is laid on both sides with the honeycomb joint seam as the starting line, the laying distance is 30-60 mm, and the laying length is 50-100 mm; The glass fiber board used in step D has a width of 15-40 mm, a thickness of 0.1-0.2 mm, and is made of plastic; it is used to control the surface quality of the joint and prevent excessive expansion of the adhesive.

[0012] Preferably, the local stabilization and curing process requirements of the honeycomb joint chamfer area in step D are specifically as follows: keeping warm at 174-186° C. for 2 to 6.5 hours.

[0013] Preferably, the W-direction splicing in step 1 is bonded on the lower panel prepreg, and the material used for bonding is consistent with that for the L-direction splicing in step C.

[0014] Preferably, the gradually varying thickness glass fiber board in step J extends from the chamfer on the honeycomb to the edge of the part with gradually varying thickness, and the gradually varying thickness glass fiber board has a width of 30-50 mm and a length of 60-90 mm.

[0015] Preferably, the curing conditions in step K are as follows: curing temperature 180±6° C., curing pressure 0.2-0.4 MPa, and holding time 120 min-360 min.

[0016] Preferably, steps A to K are all performed on the same molding tool to achieve multiple uses of one mold.

[0017] Compared with the prior art, the present invention has the following beneficial effects: 1. In the present invention, honeycomb wool materials of different thicknesses are machined into net-size honeycombs of gradually varying thicknesses by a five-axis machine tool, thereby effectively controlling the structural profile and machining errors of the net-size honeycombs and ensuring the subsequent splicing accuracy of the net-size honeycombs; 2. In the present invention, the local stabilization of the chamfered area of ​​the honeycomb joint and the L-direction splicing process are only put into the tank for curing once and are completed simultaneously, which effectively controls the collapse of the honeycomb at the chamfered position and shortens the manufacturing cycle; 3. The integrated molding process design of W-direction splicing and prepreg paving of the upper and lower panels of the composite material in the present invention reduces the number of times the mold is used and the number of times the tank is put into curing, improves the tooling efficiency while reducing the manufacturing cost and cycle, and at the same time broadens the molding method of the honeycomb sandwich structure; 4. In the packaging process of the present invention, a glass fiber board with a gradient thickness is added to the local stabilization area of ​​the film, in order to realize equal pressure on the honeycomb in the area and ensure the surface quality of the product; 5. Steps A to K of the molding process of the present invention are all performed on the same molding tool. Through reasonable honeycomb splicing design and integrated molding of composite materials, the product manufacturing cost is greatly reduced, and one mold can be used for multiple purposes. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of honeycomb L-direction splicing provided by the present invention; Figure 2 This is a cross-sectional view of a honeycomb spliced ​​in the L direction provided by the present invention; Figure 3 It is a schematic diagram of the integrated molding of honeycomb W-direction splicing and carbon fiber composite material provided by the present invention; Figure 4 It is a cross-sectional view of the W-direction splicing and integrated molding of carbon fiber composite materials provided by the present invention.

[0019] In the figure: 1. Vacuum bag; 2. Breathable felt; 3. Isolation film 2; 4. Dry peelable cloth; 5. Isolation film 1; 6. Molding tooling; 7. Fiberglass board; 8. Net size honeycomb; 9. Foaming glue; 10. Lower panel prepreg; 11. Upper panel prepreg; 12. Gradient thickness fiberglass board; 100. Seam chamfer area. DETAILED DESCRIPTION

[0020] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description and claims. It should be noted that the drawings are in very simplified form and in non-precise proportions, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention.

[0021] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and the like are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", and the like may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0022] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0023] In addition, the features, operations, and characteristics described in the specification can be combined in any appropriate manner to form various embodiments. Similarly, the steps or actions described in the method can also be adjusted in order in a manner that can be easily seen by those skilled in the art. Therefore, the various sequences in the specification and drawings are only for the purpose of describing a certain embodiment, and are not necessarily such sequences, unless otherwise stated that a certain sequence must be followed. Example

[0024] The present invention provides a composite material integrated molding process based on variable thickness honeycomb bidirectional splicing, comprising the following steps: First, multiple honeycombs of different thicknesses need to be processed by five-axis machining. The processing details are: the honeycomb angle is 5-15°, and the schematic diagram of the honeycomb shape is as follows: Figure 1 As shown, the net-size honeycomb 8 after mechanical processing needs to be dried for use, and the drying is specifically: drying at 120±8° C. for more than 60 minutes or drying at 60±8° C. for more than 120 minutes.

[0025] Next, put the dried net-size honeycombs 8 into the forming tooling 6 and arrange them according to the size and outline of the product parts. Place adhesive on the surface of the net-size honeycombs 8 to be spliced, and complete the L-direction splicing of all the net-size honeycombs 8 in sequence. The thickness of the net-size honeycombs 8 in the L-direction splicing is 15-30mm, and the foam glue 9 is completely filled into the core cells of the net-size honeycombs 8. In the thickness direction of the net-size honeycombs 8, the foam glue 9 needs to be 0-3mm higher than the core cells of the net-size honeycombs 8. Figure 2 shown.

[0026] Then, after the L-direction splicing is completed, it is necessary to perform stabilization operation on the chamfered joints of the outermost L-direction splicing net size honeycombs 8 at both ends. The stabilization material is a film, and the film is laid on the upper and lower surfaces of the honeycombs. Specifically, a layer of film is laid on the upper and lower chamfered areas 100 of the joints, and the film is laid on both sides with the honeycomb splicing seam as the starting line. The laying distance is 30-60mm, the laying length is 50-100mm, and the stabilization position is as follows: Figure 1 As shown; after the adhesive film is laid, the dry peelable cloth 4, the isolation film 5 and the glass fiber board 7 are placed in the joint chamfer area 100 in sequence, and finally the air-permeable felt and the vacuum bag are used for packaging, and the curing is performed to form a plurality of L-shaped spliced ​​honeycombs. Among them, the glass fiber board 7 used has a width of 15-40mm, a thickness of 0.1-0.2mm, and is made of plastic; it is used to control the surface quality of the joint and prevent the adhesive from excessively expanding.

[0027] Next, after the L-direction splicing of the honeycomb is completed and the stabilization film is laid, the multiple L-direction spliced ​​honeycombs are packaged and cured. The curing requirements are in accordance with the curing process requirements of the film, specifically: keeping warm at 174-186°C for 2 to 6.5 hours.

[0028] Then, the composite material carbon fiber lower panel prepreg 10 is laid on the forming tool 6 according to the manufacturing outline, and then the adhesive film used for bonding the lower panel prepreg 10 and the honeycomb is laid.

[0029] Next, before the L-direction splicing honeycombs are spliced ​​in the W direction, an isolation film needs to be placed on the composite carbon fiber lower panel prepreg, and the L-direction splicing honeycombs are arranged in different shapes and sizes on the isolation film; after determining the approximate position of the L-direction splicing honeycombs, the L-direction splicing honeycombs are spliced ​​in the W direction, and the L-direction splicing honeycombs are bonded to each other with foam glue. The splicing requirements are consistent with the L-direction splicing requirements of the honeycombs. The splicing position is as follows: Figure 3 After the W-shaped splicing of the honeycomb core is completed, lift one side of the splicing honeycomb core and slowly pull out the isolation membrane. After the isolation membrane is completely pulled out, use a laser projector to position the splicing honeycomb core to adjust the position of the splicing honeycomb core until the splicing honeycomb core is completely within the projection line.

[0030] Then, the adhesive film is laid on the spliced ​​honeycomb core again, and the upper panel prepreg 11 is laid on the adhesive film; when the product is packaged, in order to achieve the pressure equalization of the local stabilization area of ​​the adhesive film, a gradient thickness glass fiber board 12 is placed, and the gradient thickness glass fiber board 12 is placed between the packaged isolation film 2 3 and the breathable felt 2, and the packaged product is placed in a vacuum bag 1 for curing. The packaging schematic diagram is shown in FIG. Figure 4 shown.

[0031] The product is cured according to the curing process requirements of carbon fiber prepreg, specifically: curing temperature 180±6℃, curing pressure 0.2-0.4MPa, and insulation time 120min-360min.

[0032] The above description is only a description of the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention. Any changes or modifications made by a person skilled in the art in the field of the present invention based on the above disclosure shall fall within the scope of protection of the claims.

Claims

1. A composite material integrated molding process based on variable thickness honeycomb bidirectional splicing, It is characterized in that The steps include: Step A: prefabricate honeycombs, and process a plurality of honeycomb raw materials of different heights and with excess into honeycombs (8) of gradually varying thickness through a five-axis machine tool, and then dry them for later use; Step B: Arrange in the L direction, place the dried net-size honeycomb (8) into the forming tool (6), and arrange it according to the size and contour of the product; Step C: L-direction splicing, placing adhesive on the surface to be spliced ​​of the net-size honeycombs (8), and completing the L-direction splicing of all the net-size honeycombs (8) in sequence; Step D: Local stabilization of the chamfered area of ​​the honeycomb joint, locally stabilizing the chamfered area (100) of the net-size honeycomb (8) after L-direction splicing, the chamfered area (100) being located at the chamfered joint of the net-size honeycomb (8) spliced ​​in the L direction at the outermost ends; specifically, laying a layer of adhesive film on the upper and lower sides of the chamfered area (100), and after the adhesive film is laid, placing a dry peelable cloth (4), an isolation film (5) and a glass fiber board (7) in the chamfered area (100) in sequence, and finally using a breathable felt and a vacuum bag for packaging, and curing and forming; forming a plurality of L-direction spliced ​​honeycombs; Step E: Laying the composite material lower panel prepreg, laying the lower panel prepreg (10) on the forming tooling (6), and laying the adhesive film for bonding the honeycomb at the same time; Step F: Arrange in the W direction, place a layer of isolation film on the lower panel prepreg (10), and pre-position multiple L-direction spliced ​​honeycombs on the isolation film according to the size and contour of the product; Step G: W-direction splicing: placing adhesive on the surface to be spliced ​​of the L-direction spliced ​​honeycombs, and sequentially completing the W-direction splicing of all the L-direction spliced ​​honeycombs; thereby forming a spliced ​​honeycomb core; Step H: Positioning the spliced ​​honeycomb core, lift one side of the spliced ​​honeycomb core, slowly pull out the isolation film, and use a laser projector to position the spliced ​​honeycomb core after the isolation film is completely pulled out, so as to adjust the position of the spliced ​​honeycomb core until the spliced ​​honeycomb core is completely within the projection line; Step I: Laying the composite material upper panel prepreg, laying an adhesive film again on the spliced ​​honeycomb core, and laying the upper panel prepreg (11) on the adhesive film; Step J: Packaging: When packaging the product, in order to achieve pressure equalization in the local stabilization area of ​​the adhesive film, a glass fiber board (12) with a gradient thickness is placed, and the glass fiber board (12) with a gradient thickness is placed between the second isolation film (3) of the packaging and the air-permeable felt (2); Step K: Product bagging and curing: the packaged product is placed in a vacuum bag (1) for curing.

2. A composite material integrated molding process based on bidirectional splicing of variable thickness honeycombs as claimed in claim 1, It is characterized in that The net-size honeycomb (8) is an aramid paper honeycomb with a gradient thickness, the honeycomb thickness is 15-30 mm, and the honeycomb angle is 5-15°.

3. A composite material integrated molding process based on bidirectional splicing of variable thickness honeycombs as claimed in claim 2, It is characterized in that The net-size honeycomb (8) needs to be dried after mechanical processing, specifically: dried at 120±8°C for more than 60 minutes or dried at 60±8°C for more than 120 minutes.

4. A composite material integrated molding process based on variable thickness honeycomb bidirectional splicing as claimed in claim 1, It is characterized in that Step C and step D, L-direction splicing and local stabilization of the honeycomb seam chamfer area are cured at one time and completed simultaneously.

5. A composite material integrated molding process based on variable thickness honeycomb bidirectional splicing as claimed in claim 4, It is characterized in that In step D, a layer of adhesive film is laid on the upper and lower sides of the chamfered seam area (100), specifically: the adhesive film is laid on both sides with the honeycomb joint seam as the starting line, the laying distance is 30-60 mm, and the laying length is 50-100 mm; The glass fiber board (7) used in step D has a width of 15-40 mm, a thickness of 0.1-0.2 mm, and is made of plastic; it is used to control the surface quality of the joint and prevent the adhesive from expanding excessively.

6. A composite material integrated molding process based on variable thickness honeycomb bidirectional splicing as claimed in claim 4, It is characterized in that The local stabilization and curing process requirements of the honeycomb joint chamfer area in step D are specifically as follows: keeping warm at 174-186° C. for 2 to 6.5 hours.

7. A composite material integrated molding process based on variable thickness honeycomb bidirectional splicing as claimed in claim 1, It is characterized in that The W-direction splicing in the step is bonded on the lower panel prepreg (10), and the bonding material used is the same as that of the L-direction splicing in step C.

8. The composite material integrated molding process based on variable thickness honeycomb bidirectional splicing as claimed in claim 1, It is characterized in that The gradually varying thickness glass fiber board (12) in step J extends from the chamfer on the honeycomb to the edge of the part with gradually varying thickness, and the gradually varying thickness glass fiber board (12) has a width of 30-50 mm and a length of 60-90 mm.

9. The composite material integrated molding process based on bidirectional splicing of variable thickness honeycombs as claimed in claim 1, It is characterized in that The curing conditions in step K are specifically as follows: curing temperature 180±6° C., curing pressure 0.2-0.4 MPa, and holding time 120 min-360 min.

10. The composite material integrated molding process based on variable thickness honeycomb bidirectional splicing as claimed in claim 1, It is characterized in that Steps A to K are all performed on the same molding tool (6), thus achieving multiple uses of one mold.

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