Fiber composite material uniform compaction device and compaction method

Abstract

The invention relates to a fiber composite material uniform compaction device and a compaction method. The compaction device comprises a sealing gasket, a lower mold plate, a heating and cooling channel, an upper mold plate, a metal film, an oil pump, a base and the like, forming surfaces are arranged on the two opposite surfaces of the lower mold plate and the upper mold plate, and fiber prepreg is laid on the forming surfaces; the metal film is located on the lower side of the upper die plate, a metal bag cavity is formed between the metal film and the upper die plate, and the oil pump is connected with the metal bag cavity and fills oil into the metal bag cavity to generate forming pressure. The lower die plate is fixed to the base, and heating and cooling channels are arranged in the upper die plate and the lower die plate. The interior of the metal bag cavity is pressurized through the oil pump, uniform pressure is applied to all the surfaces of the fiber prepreg through expansion of the metal bag cavity, and therefore the problems that a traditional hard mold cannot apply uniform pressure to the curved surface and a soft mold cannot be attached to a blank in the whole process, so that a fiber composite material is not compacted sufficiently are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of composite materials and material forming processes, and in particular to a fiber composite material uniform compacting device and compacting method. Background Art

[0002] Fiber-reinforced composites, with their high damage tolerance, lightweight, high strength, and durability, have found widespread application in the aerospace, marine, and automotive sectors. Due to the unique nature of fiber structure, the curvature of the fiber surface shrinks, leading to defects such as wrinkles and voids during composite molding. Thoroughly and evenly compacting all surfaces of fiber prepregs can reduce defects and improve the stability of composite preform performance.

[0003] Although the composite material preform can be compacted by some compacting and forming devices in the prior art, there are still problems such as uneven compaction and insufficient compaction. For example, the Chinese patent with publication number CN220390383U discloses a carbon fiber rapid solidification forming device, which uses a curved mold and a hard pressing block for compaction. However, due to the lack of orthogonal force in the vertical pressure and the reduction of the force on the radius, it is impossible to apply uniform pressure on the curved surface. For example, the Chinese patent with publication number CN221456879U discloses a thermoplastic composite material forming mold, which uses an upper mold, a middle mold and a lower mold with precise mold closing to ensure the tightness of the mold cavity. By setting a fixing device and a stretching hole, the thermoplastic composite material preform can be stretched, thereby enabling it to maintain the unique three-dimensional woven structure of the reinforced fiber body. However, this method is relatively cumbersome to operate, and does not take into account the uneven distribution and inconsistent thickness of the prepreg during the process of placing the raw materials into the mold, resulting in uneven pressure on each part.

[0004] Furthermore, the compaction process for fiber composite preforms often involves the use of male and female molds, both of which are soft film compaction molds. For example, Chinese Patent Publication No. CN116408989A discloses composite preform fabrication equipment and methods, employing a female mold forming method for soft film compaction. However, the use of soft films can easily lead to surface curvature deviation or shrinkage of the preform, and the soft mold failing to fully adhere to the blank, resulting in insufficient preform compaction. Summary of the Invention

[0005] The primary purpose of the present invention is to address the aforementioned problems existing in the prior art. The present invention provides a device for uniformly compacting fiber composite materials. The device comprises a lower mold plate 3, an upper mold plate 5, and a metal film 6. Matching molding surfaces are provided on the lower surface of the lower mold plate 3 and the upper surface of the upper mold plate 5. The metal film 6 is disposed on the lower surface of the upper mold plate 5, forming an expandable metal bladder between the two. The pressure generated by the expansion of the metal bladder uniformly compresses the fiber prepreg on the molding surface.

[0006] In the above solution, the molding surface is a concave curved surface.

[0007] In the above solution, the uniform compaction device further comprises an oil pump 10 and an oil pipeline. The oil pump 10 is connected to the metal bladder cavity through the oil pipeline for filling the metal bladder cavity with oil and pressurizing the metal bladder cavity.

[0008] In the above solution, the metal film 6 is made of a metal material that is resistant to high temperatures and has good ductility, including but not limited to stainless steel, titanium-gold-nickel based alloy, etc.

[0009] In the above solution, at least one set of heating and cooling channels is provided in both the lower mold plate 3 and the upper mold plate 5 for heating or cooling the mold to better shape the fiber prepreg.

[0010] In the above solution, the uniform compaction device further includes a sealing gasket 2, which is located between the lower mold plate 3 and the upper mold plate 5 and squeezes the peripheral edge of the metal cavity when the mold is closed, thereby achieving a better sealing effect.

[0011] In the above solution, the uniform compacting device further includes a base 11 , on which a mounting groove is provided, and the lower mold plate 3 is fixed in the mounting groove of the base 11 .

[0012] The second object of the present invention is to provide a method for using the above-mentioned fiber composite material uniform compaction device, including: laying the fiber prepreg on the molding surface of the lower mold plate 3, closing the mold and injecting oil into the metal sac cavity to make it expand, and applying uniform pressure to the fiber prepreg through the metal sac cavity; after hot pressing, opening the mold and taking out the fiber composite material product.

[0013] In the above solution, the fiber prepreg is specifically a fiber-reinforced thermosetting composite material or a thermoplastic composite material.

[0014] In the above scheme, the temperature of hot pressing molding does not exceed 450° C., and the pressure does not exceed 3 MPa.

[0015] In the above scheme, the molding process of the fiber prepreg includes cyclical hot pressing molding and cooling and solidification.

[0016] Compared with existing similar products or technologies, the advantages of this invention are mainly reflected in the following points: (1) An oil pump is used to pressurize the interior of the metal bladder. During the pressurization process, uniform pressure is applied to all surfaces of the fiber prepreg through the expansion of the metal bladder. This avoids the problem that the hard mold cannot apply uniform pressure on the curved surface due to the lack of orthogonal force on the vertical pressure and the reduction of force on the radius. In addition, the soft mold is prone to offset or shrinkage at the curvature change position during use, and cannot fit the blank throughout the process, resulting in insufficient compaction of the carbon fiber composite material, no obvious improvement in surface quality, and low degree of internal quality optimization.

[0017] (2) Through the design of the metal sac and oil pressure system, the hydrostatic compaction method is used to effectively reduce the problem of fiber surface curvature shrinkage, avoid defects such as wrinkles and gaps in composite products, and greatly improve the internal and surface quality of composite products.

[0018] (3) It is not only suitable for a variety of thermosetting and thermoplastic composite materials (such as epoxy resin, polypropylene, polyetheretherketone, etc.), but also can meet the molding requirements of different materials. It also eliminates vacuum bags and auxiliary materials, significantly saving costs and time. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the overall structure of the fiber composite material uniform compaction device of the present invention.

[0020] Figure 2 It is a schematic cross-sectional view of the fiber composite material uniform compacting device of the present invention.

[0021] Figure 3 It is a partial cross-sectional view of the fiber composite material uniform compacting device according to the present invention.

[0022] Figure 4 This is a diagram showing the compaction principle of the fiber composite material uniform compaction device of the present invention.

[0023] Figure 5 It is a process flow chart of the present invention.

[0024] Figure 6 This is a temperature-pressure variation curve during molding of the fiber composite material uniform compacting device of the present invention.

[0025] Figure 7 The figure is a photo of a fiber composite molded product produced by using the fiber composite material uniform compacting device of the present invention.

[0026] Description of the drawings: 1-pressure inlet, 2-sealing gasket, 3-lower mold plate, 4-heating and cooling channel, 5-upper mold plate, 6-metal film, 7-fiber prepreg, 8-oil cavity, 9-release agent, 10-oil pump, 11-base. DETAILED DESCRIPTION

[0027] To enable those skilled in the art to fully understand the technical solutions and beneficial effects of the present invention, the following is a further detailed description with reference to specific embodiments and accompanying drawings. It should be emphasized that the following embodiments are merely preferred embodiments and do not constitute any limitation of the present invention. The present invention may also have many other embodiments, and any simple improvements or substitutions made on this basis will fall within the scope of protection of the present invention.

[0028] like Figure 1 The fiber composite material uniform compaction device shown in the figure primarily comprises an upper mold plate 5, a lower mold plate 3, and a base 11. The lower mold plate 3 is fixed to the base 11, while the upper mold plate 5 is positioned directly above the lower mold plate 3 and can be controlled to move up and down to close or open the mold. The lower surface of the upper mold plate 5 and the upper surface of the lower mold plate 3 are provided with matching curved molding surfaces, onto which the fiber prepreg is laid for hot pressing.

[0029] like Figure 2-4 As shown, the structure of the upper mold plate 5 is crucial and forms the core of the present invention. A metal film 6 is positioned at the bottom of the upper mold plate 5. The space between the metal film 6 and the lower surface of the upper mold plate 5 forms an expandable oil cavity 8. Metal film 6 is made of a high-temperature-resistant and ductile metal such as stainless steel or a titanium-nickel alloy. When filled with oil, the cavity expands outward, generating varying pressures.

[0030] As a supporting device, a pressure inlet 1 and a matching oil pump 10 are provided on the side of the upper mold plate 5. The pressure inlet 1 is connected to the oil pump 10 and the oil chamber 8 respectively through a hydraulic pipeline. When the oil pump 10 is started, the hydraulic oil enters the cavity (i.e., the oil chamber 8) between the metal film 6 and the upper mold plate 5, and evenly compacts the fiber prepreg 7 (pressure size 0-3MPa) to make it better shaped. The specific principle is as follows Figure 4 shown.

[0031] To ensure the best possible product formation, a gasket 2 (high-temperature graphite gasket) is installed between the upper mold plate 5 and the lower mold plate 3. The gasket 2 spans the entire perimeter of the bladder cavity, allowing the hydraulic system to bottom out on it. The gasket applies force to seal the oil within the bladder cavity.

[0032] like Figure 2-3 As shown, heating and cooling channels 4 are provided inside the upper and lower mold plates 5 and 3, through which a heat-conducting medium circulates, thereby heating or cooling the fiber prepreg 7 during the molding process. The entire device has a temperature control range of -80°C to 450°C, achieving good heat distribution.

[0033] The fiber composite material uniform compacting device provided by the present invention has Figure 1The upper and lower mold layout can also adopt other layouts such as left and right molds or front and back molds, and can achieve the technical effects of the present invention.

[0034] The process flow chart of the above fiber composite material uniform compaction device is as follows: Figure 5 As shown, the specific steps include: S1: Spraying a release agent on the molding surface of the lower mold plate 3.

[0035] S2: Lay fiber prepreg on the molding surface of the lower mold plate 3 and compact it tightly.

[0036] S3: The upper mold plate 5 and the metal film 6 move downward synchronously, and are pressurized at a constant rate so that the fiber prepreg 7 layer is fully infiltrated and fits the surface of the lower mold plate 3.

[0037] S4: When the metal film 6 contacts the mold frame, a sealing gasket is laid along the circumference of the mold frame.

[0038] S5: Connect the pressure inlet 1 to the oil pump 10 via a hydraulic line. Start the oil pump 10 to supply oil and pressurize the metal bladder cavity, forming a closed oil cavity 8. The oil cavity 8 applies uniform molding pressure to all surfaces of the fiber prepreg 7. The pressure can be adjusted within a range of 0 to 3 MPa.

[0039] S6: The mold press hydraulic system is activated, and the pressure mechanism descends until it contacts the gasket, forming a mechanical stop. The elastic deformation of the gasket generates contact pressure, which is used to maintain the oil in the oil chamber in a good sealing state.

[0040] S7: Start the temperature control system to gradually increase the temperature of the hydraulic oil and the fiber prepreg 7 through the heating cooling channel 4 to achieve melt infiltration of the prepreg resin matrix.

[0041] S8: The mold press hydraulic system is activated to close the mold. The temperature control system implements programmed temperature control within a range of -80°C to 450°C. Heating time can be adjusted from minutes to hours, depending on process requirements. Cooling is performed at a rate of 1-10°C / min to remelt and solidify the fiber prepreg resin matrix.

[0042] S9: The fiber prepreg 7 is subjected to a cyclic heating-cooling-curing process to achieve multi-cycle compaction of the fiber prepreg 7, so as to achieve full impregnation of the fiber with the resin matrix and form a uniform and dense composite material structure.

[0043] Figure 6This is a graph showing temperature-pressure variations during molding of fiber prepreg using the fiber composite material uniform compaction device of the present invention. The graph illustrates the basic temporal trends of resin melting, heating, and cooling temperatures, as well as molding pressure. This process ensures that the resin matrix is fully heated and melted, thereby impregnating the fibers to form a uniform, dense composite part.

[0044] Figure 7 This is a photograph of a fiber composite molded product produced using the fiber composite uniform compacting device described herein. As can be seen from the image, the fiber composite molded product is compacted fairly evenly, with a very smooth surface and no noticeable wrinkles or other defects. This demonstrates that the fiber composite uniform compacting device provided by the present invention effectively improves the internal and surface quality of the product.

Claims

1. A fiber composite material uniform compacting device, characterized by: The device includes a mold plate A, a mold plate B, and a film. Matching molding surfaces are provided on the two opposite surfaces of mold plate A and mold plate B; the film is arranged on one side of the molding surface of mold plate A or mold plate B, and forms an expandable cavity between the mold plate A or mold plate B. During the molding process, the cavity expands and evenly squeezes the fiber prepreg laid on the molding surface.

2. The fiber composite material uniform compacting device according to claim 1, characterized in that: The molding surface is a curved surface.

3. The fiber composite material uniform compacting device according to claim 1, characterized in that: The uniform compacting device further comprises an oil pump and an oil delivery pipeline, wherein the oil pump is communicated with the sac cavity through the oil delivery pipeline.

4. The fiber composite material uniform compacting device according to claim 1, characterized in that: The film is made of a metal material that is resistant to high temperatures and has good ductility, preferably stainless steel or titanium-nickel based alloy.

5. The fiber composite material uniform compacting device according to claim 1, characterized in that: At least one set of heating and cooling channels is provided inside mold plate A and mold plate B.

6. The fiber composite material uniform compacting device according to claim 1, characterized in that: The uniform compacting device further comprises a sealing gasket, which is located between the mold plate A and the mold plate B and presses the outer periphery of the bladder cavity when the mold is closed.

7. The fiber composite material uniform compacting device according to claim 1, characterized in that: The uniform compacting device further comprises a base, and the mold plate A or the mold plate B is fixed on the base.

8. The method for using the fiber composite material uniform compacting device according to any one of claims 1 to 7, characterized in that The method includes: laying fiber prepreg on the molding surface of mold plate A or mold plate B, closing the mold and injecting oil into the cavity to expand it, uniformly squeezing the fiber prepreg in the expanded cavity to complete hot pressing molding, and opening the mold to obtain a fiber composite material product.

9. The method according to claim 8, wherein: The fiber prepreg is specifically a fiber-reinforced thermosetting composite material or a fiber-reinforced thermoplastic composite material.

10. The method according to claim 8, wherein: The temperature of hot pressing the fiber prepreg does not exceed 450°C, and the pressure does not exceed 3MPa.

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