Composite material C-shaped structure preformed body thermal diaphragm forming method capable of eliminating surface fiber wrinkles

Abstract

The invention discloses a composite material C-shaped structure preformed body thermal diaphragm forming method capable of eliminating surface fiber wrinkles, a C-shaped structure forming tool is adopted as a forming tool, material piece wrinkles and deformation caused in the transfer process of a composite material C-shaped structure preformed body are avoided, the C-shaped structure forming tool is preheated before a diaphragm is heated, and the thermal diaphragm is formed. Resin in the resin-based composite material has good flowability, the friction coefficient between composite material prepreg flat plates is reduced, interlayer slippage is facilitated, a pressing plate is adopted for local treatment on a wrinkled area after a thermal diaphragm is formed, the pressing plate applies pressure to the wrinkled area in the curing process, and therefore the wrinkled area is cured. The composite material C-shaped structure preformed body is completely placed on the forming tool in a shape follow-up mode, after the composite material C-shaped structure preformed body is cured, surface fibers are smooth, the performance is not affected, and surface fiber wrinkles in the composite material C-shaped structure preformed body thermal diaphragm forming process can be effectively removed.

Description

Technical Field

[0001] The invention belongs to the technical field of composite material molding, and in particular relates to a thermal diaphragm molding method for a composite material C-shaped structure preform capable of eliminating surface fiber wrinkles. Background Art

[0002] Resin-based composite materials are increasingly used in the aerospace field due to their high specific strength, specific modulus, fatigue resistance, heat resistance and other properties. However, the traditional manual laying manufacturing method is inefficient, has a long cycle, and requires high skills from the operator. For C-type, L-type, and T-type composite parts, manual laying is usually used for forming, and the product quality is unstable. Therefore, it is of great significance to develop an automated manufacturing process for composite materials with complex curved structures.

[0003] For C-type structures, existing automation technologies mostly use automatic tape laying machines for laying, and adopt hot diaphragm process for the molding and preparation of composite material C-type structure preforms. After the thermosetting prepreg is heated, the resin viscosity is high and the fluidity is poor, which makes it difficult to slide. Fiber wrinkles will be generated during the hot diaphragm process, affecting the surface quality and mechanical properties of the product. Therefore, we propose a hot diaphragm molding method for composite material C-type structure preforms that eliminates surface fiber wrinkles. Summary of the invention

[0004] The object of the present invention is to provide a thermal diaphragm forming method for a composite material C-shaped structure preform which eliminates surface fiber wrinkles, so as to solve the problems raised in the above-mentioned background technology.

[0005] To achieve the above object, the present invention provides the following technical solution: a thermal diaphragm forming method of a composite material C-shaped structure preform with surface fiber wrinkles eliminated, comprising the following steps: S1. Preparation of composite material prepreg flat plate: Using an automatic tape laying machine to lay composite material prepreg sheets on a flat tooling, using laser projection to determine the position of the composite material prepreg sheets on the flat tooling, and then using a pressing roller to roll the composite material prepreg sheets to obtain a composite material prepreg flat plate; S2, C-type structure forming tooling heating: Use an oven to preheat the C-type structure forming tooling, then transfer the composite material prepreg flat plate from the flat plate tooling to the C-type structure forming tooling on the hot diaphragm machine tool through a vacuum adsorption device, and then adjust the positioning of the composite material prepreg flat plate on the C-type structure forming tooling through positioning ears; S3. Composite material prepreg flat thermal insulation film molding: The temperature of the hot diaphragm is determined by testing the viscosity-temperature curve of the composite prepreg flat plate, and the composite prepreg flat plate is heated to the set temperature and heat preservation is started through multi-stage rate control in the hot diaphragm vacuum stage, and then interlayer sliding molding is performed through the pressurization system to obtain a composite C-type structure preform, and the composite C-type structure preform is depressurized after the temperature drops to room temperature; S4. Elimination of wrinkles on composite C-shaped preforms: An R-shaped pressing plate is placed in the R-angle wrinkle area of ​​the composite material C-shaped structure preform, and a flat pressing plate is placed in the edge wrinkle area of ​​the composite material C-shaped structure preform, and then the R-shaped pressing plate and the flat pressing plate are fixed with a pressure-sensitive tape, and the composite material C-shaped structure preform begins to be packaged and cured, and the R-shaped pressing plate and the flat pressing plate are used for hot diaphragm prepressing again, and wrinkles in the R-angle wrinkle area and the edge wrinkle area of ​​the composite material C-shaped structure preform are eliminated by the R-shaped pressing plate and the flat pressing plate; S5. Encapsulation and curing of composite material C-type structure preform The composite material C-type structure preform completes packaging and curing, the R-type pressure plate and the flat pressure plate on the packaged and cured composite material C-type structure preform are demoulded, the composite material C-type structure preform is inspected, the surface limiting of the R corner area and the edge strip area of ​​the composite material C-type structure preform is smooth, and the molding of the composite material C-type structure preform is completed.

[0006] Preferably, in S2, the preheating temperature of the oven for the C-shaped structure forming tooling is 65-75°C.

[0007] Preferably, in S2, the positioning tabs are arranged in the surplus area of ​​the composite prepreg flat plate.

[0008] Preferably, in S3, the temperature of the hot diaphragm of the composite material prepreg flat plate is 75-85° C., and the insulation time is 15-25 min.

[0009] Preferably, in S3, the multi-stage rate of the hot diaphragm vacuum in the multi-stage rate control through the hot diaphragm vacuum stage is: The first stage of vacuuming and pressurizing rate is 0-4kPa / min; The second stage vacuuming and pressurizing rate is 0-50kPa / min; The third stage vacuuming and pressurizing rate is 0-200kPa / min.

[0010] Preferably, in S4, the R-type press plate and the flat press plate are press plates made of glass fiber prepreg and have a thickness of 0.5 mm to 1.5 mm.

[0011] Preferably, in S4, before the R-shaped pressing plate and the flat pressing plate are placed, a layer of wet peelable cloth is spread on the R-shaped pressing plate and the flat pressing plate.

[0012] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a composite material C-type structure preform thermal diaphragm forming method for eliminating surface fiber wrinkles. In the method, a C-type structure forming tool is used as a forming tool to avoid wrinkles and deformation of the material sheet caused during the transfer process of the composite material C-type structure preform; before the thermal diaphragm treatment, the C-type structure forming tool is preheated to increase the temperature of the composite material prepreg flat plate attached to the C-type structure forming tool, so that the resin in the resin-based composite material has good fluidity, and the friction coefficient between the composite material prepreg flat plates is reduced to facilitate interlayer slip; after the thermal diaphragm treatment, local treatment is performed on the area where wrinkles appear, and a pressure plate with a thin thickness and high rigidity is selected to ensure that the pressure plate has good adaptability to the parts and has a certain shape retention effect. The local pressure plate transmits pressure better, and the pressure plate applies pressure to the wrinkle area during the curing process, so that the composite material C-type structure preform is completely shaped according to the forming tool. After the composite material C-type structure preform is cured, the surface fibers are smooth and smooth, and the performance is not affected, and the surface fiber wrinkles in the composite material C-type structure preform during the thermal diaphragm forming process can be effectively removed. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a schematic diagram of the structure of the composite material C-shaped structure before molding; Figure 2 It is a schematic diagram of the structure of the composite material C-shaped structure after molding of the present invention; Figure 3 It is a schematic structural diagram of the placement of the R angle pressure plate behind the thermal diaphragm of the composite material C-type structure preform of the present invention; Figure 4 It is a schematic diagram of the fiber orientation in the R-angle region of the composite material C-shaped structure preform after curing of the present invention; Figure 5 It is a structural schematic diagram of placing a flat platen after a heat diaphragm of a composite material C-shaped structure preform of the present invention; Figure 6 It is a schematic diagram of the fiber orientation in the edge strip area of ​​the composite material C-shaped structure preform after curing of the present invention.

[0014] In the figure: 1. Composite material prepreg flat plate; 2. C-type structure forming tooling; 3. Composite material C-type structure preform; 4. R-type pressing plate; 5. R-corner wrinkle area; 6. R-corner area after curing; 7. Flat plate pressing plate; 8. Edge strip wrinkle area; 9. Edge strip area after curing; 10. Wet peelable cloth. DETAILED DESCRIPTION

[0015] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0016] See also Figure 1-Figure 6 The present invention provides a composite material C-shaped structure preform thermal diaphragm forming method for eliminating surface fiber wrinkles, comprising the following steps: S1. Preparation of composite material prepreg flat plate: Using an automatic tape laying machine to lay composite material prepreg sheets on a flat plate tooling, using a laser projection method to determine the position of the composite material prepreg sheets on the flat plate tooling, and then using a pressing roller to roll the composite material prepreg sheets to obtain a composite material prepreg flat plate 1; S2, C-type structure forming tooling heating: Use an oven to preheat the C-shaped structure forming tool 2 to 70°C, then transfer the composite material prepreg flat plate 1 from the flat plate tool to the C-shaped structure forming tool 2 on the hot diaphragm machine tool through a vacuum adsorption device, and then adjust the positioning of the composite material prepreg flat plate 1 on the C-shaped structure forming tool 2 through positioning ears; S3. Composite material prepreg flat thermal insulation film molding: The temperature of the hot diaphragm is determined by testing the viscosity-temperature curve of the composite material prepreg plate 1, and the composite material prepreg plate 1 is heated to 80° C. and kept warm for 20 minutes by performing multi-stage rate control during the hot diaphragm vacuum stage, and then interlayer slip molding is performed through a pressurizing system to obtain a composite material C-type structure preform 3, and the composite material C-type structure preform 3 is depressurized after being cooled to room temperature; The pressurizing system is composed of a vacuum pump, a vacuum pressure gauge and a frequency conversion controller. The frequency conversion controller controls the operation of the vacuum pump to realize vacuum pumping rate control. The vacuum pressure is used to control the process pressure of the hot diaphragm, so that the composite material prepreg flat plate 1 is bent and fitted to the C-shaped structure forming tooling 2 to be preformed into a composite material C-shaped structure preform 3; Interlayer sliding molding: The C-type structure molding tool 2 is placed on the hot diaphragm machine, and the composite material prepreg flat plate 1 is placed on the C-type structure molding tool 2. Then, an isolation film and a vacuum bag are placed on the composite material prepreg flat plate 1 in sequence, and the vacuum bag is covered on the hot diaphragm machine and sealed with a sealing strip. After sealing, the hot diaphragm machine is evacuated for pressurization. During the pressurization process, the vacuum bag gradually fits with the C-type structure molding tool 2 on the hot diaphragm machine due to the effect of pressure. During the process of fitting the vacuum bag and the C-type structure molding tool 2, the composite material prepreg flat plate 1 structure between the vacuum bag and the C-type structure molding tool 2 is driven to slide between the layers, and the flat plate structure is bent into a C-type structure, fitting the molding surface of the C-type structure molding tool 2; In S3, the hot diaphragm vacuum multi-stage rate in the multi-stage rate control through the hot diaphragm vacuum stage is: The vacuuming and pressurizing rate of the first stage is 0-4 kPa / min, and the vacuuming rate is low to avoid the problem of out-of-plane buckling of the surface fibers of the composite material C-shaped structure preform 3; The vacuuming and pressurizing rate of the second stage is 0-50 kPa / min, so as to ensure that the composite material C-shaped structure preform 3 can fit the C-shaped structure forming tool 2; The third stage vacuuming and pressurizing rate is 0-200 kPa / min, and the rapid pressurization ensures that the composite material C-shaped structure preform 3 is completely attached to the C-shaped structure forming tool 2; S4. Elimination of wrinkles on composite C-shaped preforms: An R-shaped pressing plate 4 is placed in the R-angle wrinkle area 5 of the composite material C-shaped structure preform 3, and a flat pressing plate 7 is placed in the edge strip wrinkle area 8 of the composite material C-shaped structure preform 3. Before the R-shaped pressing plate 4 and the flat pressing plate 7 are placed, a layer of wet peelable cloth 10 is laid on the R-shaped pressing plate 4 and the flat pressing plate 7 for easy demoulding. Then, the R-shaped pressing plate 4 and the flat pressing plate 7 are fixed with a pressure-sensitive tape. The composite material C-shaped structure preform 3 begins to be packaged and cured, and the R-shaped pressing plate 4 and the flat pressing plate 7 are used for hot diaphragm prepressing again. The R-shaped pressing plate 4 and the flat pressing plate 7 are used to eliminate wrinkles in the R-angle wrinkle area 5 and the edge strip wrinkle area 8 of the composite material C-shaped structure preform 3. In S4, the R-shaped pressing plate 4 and the flat pressing plate 7 are pressing plates made of glass fiber prepreg and have a thickness of 0.5 mm to 1.5 mm; S5. Encapsulation and curing of composite material C-type structure preform The composite material C-type structure preform 3 completes packaging and curing, and the R-shaped pressure plate 4 and the flat pressure plate 7 on the composite material C-type structure preform 3 after packaging and curing are demolded, and the composite material C-type structure preform 3 is inspected. The surface of the composite material C-type structure preform 3 is limited smoothly after curing in the R corner area 6 and the edge strip area 9 after curing, and the molding of the composite material C-type structure preform is completed.

[0017] In this embodiment, the positioning ear piece is arranged in the residual area of ​​the composite material prepreg flat plate, so as to facilitate the positioning and use of the composite material prepreg flat plate.

[0018] The present invention provides a composite material C-type structure preform hot diaphragm forming method for eliminating surface fiber wrinkles. In the method, a C-type structure forming tool 2 is used as a forming tool to avoid wrinkles and deformation of the material sheet caused during the transfer process of the composite material C-type structure preform 3; before the hot diaphragm treatment, the C-type structure forming tool 2 is preheated to increase the temperature of the composite material prepreg flat plate 1 attached to the C-type structure forming tool 2, so that the resin in the resin-based composite material has better fluidity, and the friction coefficient between the composite material prepreg flat plates 1 is reduced to facilitate interlayer slip; after the hot diaphragm treatment, local treatment is performed on the area where wrinkles appear, and a thin thickness and high rigidity pressing plate is selected to ensure that the pressing plate has good adaptability to the parts and has a certain shape retention effect. The local pressing plate transmits pressure better, and the pressing plate applies pressure to the wrinkle area during the curing process, so that the composite material C-type structure preform 3 is completely shaped according to the forming tool. After the composite material C-type structure preform 3 is cured, the surface fibers are smooth and smooth, and the performance is not affected, and the surface fiber wrinkles in the composite material C-type structure preform during the hot diaphragm forming process can be effectively removed.

[0019] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A thermal diaphragm forming method for a composite material C-shaped preform with surface fiber wrinkles eliminated, characterized in that: The steps include: S1. Preparation of composite material prepreg flat plate: Using an automatic tape laying machine to lay composite material prepreg sheets on a flat tooling, using laser projection to determine the position of the composite material prepreg sheets on the flat tooling, and then using a pressing roller to roll the composite material prepreg sheets to obtain a composite material prepreg flat plate; S2, C-type structure forming tooling heating: Use an oven to preheat the C-type structure forming tooling, then transfer the composite material prepreg flat plate from the flat plate tooling to the C-type structure forming tooling on the hot diaphragm machine tool through a vacuum adsorption device, and then adjust the positioning of the composite material prepreg flat plate on the C-type structure forming tooling through positioning ears; S3. Composite material prepreg flat thermal insulation film molding: The temperature of the hot diaphragm is determined by testing the viscosity-temperature curve of the composite prepreg flat plate, and the composite prepreg flat plate is heated to the set temperature and heat preservation is started through multi-stage rate control in the hot diaphragm vacuum stage, and then interlayer sliding molding is performed through the pressurization system to obtain a composite C-type structure preform, and the composite C-type structure preform is depressurized after the temperature drops to room temperature; S4. Elimination of wrinkles on composite C-shaped preforms: An R-shaped pressing plate is placed in the R-angle wrinkle area of ​​the composite material C-shaped structure preform, and a flat pressing plate is placed in the edge wrinkle area of ​​the composite material C-shaped structure preform, and then the R-shaped pressing plate and the flat pressing plate are fixed with a pressure-sensitive tape, and the composite material C-shaped structure preform begins to be packaged and cured, and the R-shaped pressing plate and the flat pressing plate are used for hot diaphragm prepressing again, and wrinkles in the R-angle wrinkle area and the edge wrinkle area of ​​the composite material C-shaped structure preform are eliminated by the R-shaped pressing plate and the flat pressing plate; S5. Encapsulation and curing of composite material C-type structure preform The composite material C-type structure preform completes packaging and curing, the R-type pressure plate and the flat pressure plate on the packaged and cured composite material C-type structure preform are demoulded, the composite material C-type structure preform is inspected, the surface limiting of the R corner area and the edge strip area of ​​the composite material C-type structure preform is smooth, and the molding of the composite material C-type structure preform is completed.

2. The method for forming a thermal diaphragm of a composite material C-shaped preform with surface fiber wrinkles eliminated according to claim 1, characterized in that: In S2, the preheating temperature of the oven for the C-type structure forming tooling is 65-75°C.

3. The method for forming a thermal diaphragm of a composite material C-shaped preform with surface fiber wrinkles eliminated according to claim 1, characterized in that: In S2, positioning tabs are arranged at the excess area of ​​the composite prepreg flat sheet.

4. The method for forming a thermal diaphragm of a composite material C-shaped preform with surface fiber wrinkles eliminated according to claim 1, characterized in that: In S3, the temperature of the hot diaphragm of the composite prepreg flat plate is 75-85°C, and the insulation time is 15-25 minutes.

5. The method for forming a thermal diaphragm of a composite material C-shaped preform with surface fiber wrinkles eliminated according to claim 1, characterized in that: In S3, the hot diaphragm vacuum multi-stage rate in the multi-stage rate control through the hot diaphragm vacuum stage is: The first stage of vacuuming and pressurizing rate is 0-4kPa / min; The second stage vacuuming and pressurizing rate is 0-50kPa / min; The third stage vacuuming and pressurizing rate is 0-200kPa / min.

6. The method for forming a thermal diaphragm of a composite material C-shaped preform with surface fiber wrinkles eliminated according to claim 1, characterized in that: In S4, the R-type press plate and the flat press plate are press plates made of glass fiber prepreg and have a thickness of 0.5 mm to 1.5 mm.

7. The method for forming a thermal diaphragm of a composite material C-shaped preform with surface fiber wrinkles eliminated according to claim 1, characterized in that: In S4, before the R-type pressing plate and the flat pressing plate are placed, a layer of wet peelable cloth is spread on the R-type pressing plate and the flat pressing plate.

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