A resin-based composite door body and a molding method thereof

Abstract

The application discloses a resin-based composite material door body and a forming method thereof. The forming method comprises the following steps: firstly, designing the door body according to actual needs; then, adopting prepreg for an outer skin, adopting glass fiber cloth + impregnated resin for an inner skin, adopting prepreg for a layer which cannot be reached by liquid resin, and adopting dry fiber reinforced material for a layer which can be freely flowed by liquid resin. In this way, the dry and wet combination can realize integrated forming for a product with complex layers, one or more kinds of functional materials, multiple pre-buried parts, multiple reinforcing ribs, a metal frame, a door frame and other structures, can significantly improve production efficiency and reduce cost, and can significantly improve the overall structural strength of the product.

Description

Technical Field

[0001] This invention relates to the field of integral molding technology for composite material doors, and in particular to a resin-based composite material door and its molding method. Background Technology

[0002] Resin-based composite materials are widely used in various fields due to their lightweight, high strength, and flexible design advantages. In the military industry, there is an increasingly urgent need for composite material structures that are lightweight, high-strength, and integrate multiple functions such as stealth, bulletproofing, and thermal insulation. They have already been applied in products such as military shelters and ship doors. Currently, the traditional method mainly involves molding the metal door frame and composite door panel separately, and then connecting them with other metal parts using bolts and adhesives. This method has low production efficiency, limited weight reduction, and poor sealing performance. Summary of the Invention

[0003] This invention provides a resin-based composite material door body and its molding method, which overcomes the defects of the prior art such as low production efficiency, limited weight reduction and poor sealing performance.

[0004] To achieve the above objectives, the present invention proposes a molding method for a resin-based composite material door, comprising the following steps:

[0005] S1: Design the matching dimensions of the door panel and door frame, select the mold, pre-treat the mold, and lay out the release cloth;

[0006] S2: Lay two layers of prepreg on the mold after S1, cut, lay vacuum auxiliary material, and vacuum pre-compact.

[0007] S3: Lay a layer of resin film on the prepreg after S2, and lay the processed PVC foam on the resin film;

[0008] S4: A layer of resin film and a layer of functional material are sequentially laid on the PVC foam, and then the processed polyurethane foam is laid on the functional material;

[0009] S5: Wrap two layers of continuous glass fiber felt around the metal embedded part, and then embed the metal embedded part into the set position on the polyurethane foam;

[0010] S6: Lay two layers of fiberglass cloth on the polyurethane foam to obtain the door panel layup;

[0011] S7: Wrap two layers of continuous glass fiber mat around the processed metal door frame, then nest the metal door frame around the door panel layer, lay vacuum auxiliary materials, and set the glue inlet and outlet.

[0012] S8: Vacuum infusion of resin, vacuum impregnation, drying with mold, demolding, and post-treatment to obtain a resin-based composite door body.

[0013] To achieve the above objectives, the present invention also proposes a resin-based composite material door body, which is prepared by the molding method described above; the door body includes a door panel and a metal door frame, wherein the metal door frame covers the periphery of the door panel.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0015] The molding method for resin-based composite door bodies provided by this invention first designs the door body (including matching door panels and door frames) according to actual needs; then, the outer skin uses prepreg, and the inner skin uses glass fiber cloth + impregnated resin. In the layup where liquid resin cannot reach well, prepreg is used, and in the area where liquid resin can flow freely, dry fiber reinforced material is used for layup. This dry and wet combination method can achieve one-piece molding for products with complex layup, requiring composite of one or more functional materials, multiple pre-embedded parts, multiple reinforcing ribs, and structures with metal frames, door frames, etc., and significantly improves production efficiency, reduces costs, and significantly improves the overall structural strength of the product. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0017] Figure 1 A schematic diagram of the front of a door body prepared by the molding method of the resin-based composite material door body provided by the present invention;

[0018] Figure 2 The interface diagram of the door body prepared by the molding method of the resin-based composite material door body provided by the present invention.

[0019] The following are the reference numerals: 1: Door panel; 2: Metal door frame (i.e., the metal edging of the door panel); 3: Metal embedded part; 4: Metal door frame groove; 5: Metal door frame edge gap; 6: Outer skin; 7: Inner skin.

[0020] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0022] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0023] Unless otherwise specified, all medicines / reagents used are commercially available.

[0024] This invention proposes a molding method for a resin-based composite door, comprising the following steps:

[0025] S1: Design the matching dimensions of the door panel and door frame, select the mold, pre-treat the mold, and lay out the release cloth.

[0026] S2: Lay two layers of prepreg on the mold that has passed through S1, cut, lay vacuum auxiliary material, and vacuum pre-compact.

[0027] S3: A layer of resin film is laid on the prepreg after S2, and the processed PVC foam is laid on the resin film.

[0028] Resin film refers to a flexible resin film. The resin system in it is similar to the resin in prepreg, and is also in an intermediate state. Its main function is to act as an adhesive. Some resin films have a thin layer of polyester or fiberglass mesh added for process control and ease of resin mold application.

[0029] PVC (polyvinyl chloride) foam can increase the specific stiffness of the product system, reduce the overall weight of the product, and also play a role in wave transmission, wave absorption (by adding a wave-absorbing coating), and heat insulation.

[0030] S4: A layer of resin film and a layer of functional material are sequentially laid on the PVC foam, and then the processed polyurethane foam is laid on the functional material.

[0031] Functional materials are black thin films that can absorb radar waves. Other functional layer materials include conductive copper mesh and frequency-selective layers, which can achieve different functions depending on the design requirements.

[0032] S5: Wrap two layers of continuous glass fiber felt around the metal embedded part, and then embed the metal embedded part into the set position on the polyurethane foam.

[0033] Metal embedded parts are mainly used to facilitate the connection of the door body with other components. They require screwing, tapping, and installation of parts such as door locks, door hinges, and limit switches.

[0034] S6: Two layers of fiberglass cloth are laid on the polyurethane foam to obtain the door panel layup.

[0035] S7: Wrap two layers of continuous glass fiber mat around the processed metal door frame, then nest the metal door frame around the door panel layer, lay vacuum auxiliary materials, and set the glue inlet and outlet.

[0036] S8: Vacuum infusion of resin, vacuum impregnation, drying with mold, demolding, and post-treatment to obtain a resin-based composite door body.

[0037] The molding method provided by this invention is low-cost and high-efficiency: product lay-up, metal parts, door frames, etc. can be laid up and pre-embedded and placed in one go, without the need for multiple moldings. This reduces a lot of post-processing work and curing waiting time after multiple moldings, greatly improves production efficiency and reduces process and labor costs.

[0038] High overall strength: The one-piece molding process not only improves production efficiency and reduces costs, but also ensures the continuity of reinforcing fibers by laying the required materials and metal embedded parts in one go. These fibers are connected by the fiber material, and the liquid resin is also injected in one go, filling the pores and gaps between the materials, which greatly improves the overall strength of the product.

[0039] Flexible design: The use of prepreg and vacuum casting, a dry and wet molding process, makes product design more flexible and reduces design limitations. It allows for the design of various functional materials (wave transmission, stealth, shielding, heat insulation, heat preservation, bulletproof, etc.) in products, making it easier to achieve multi-functionality.

[0040] Preferably, in step S1, the preprocessing specifically includes:

[0041] Wipe the mold clean with acetone, alcohol or other cleaning agents to remove dirt and dust;

[0042] After drying at room temperature, apply release agent to the mold several times, with a 15-minute interval between each application. After applying the release agent, wait 30 minutes before laying the release cloth.

[0043] The main materials for molds are steel and aluminum, as well as fiberglass molds and carbon fiber molds commonly used for resin-based composite materials. Molds are also divided into female molds and male molds. Depending on the product characteristics and requirements, the choice between a female mold and a male mold will be considered during the product design stage. The choice between a female mold and a male mold is not different in the technical solution of this invention.

[0044] Release agents are liquids or pastes (also called release waxes) used to separate cured products from molds.

[0045] Preferably, the release cloth is a PTFE release cloth. This allows the product to be easily demolded from the mold. Furthermore, laying a layer of PTFE release cloth at this point provides ventilation, allowing residual air between the outer skin prepreg and the mold to escape, improving product quality and reducing defects.

[0046] Preferably, in step S2, the prepreg is one of epoxy quartz fiber prepreg, epoxy glass fiber prepreg, epoxy aramid fiber prepreg, epoxy carbon fiber prepreg, cyanate ester prepreg, bismaleimide prepreg, and polyimide prepreg. The specific choice depends on actual needs.

[0047] Preferably, in step S2, the cutting specifically involves:

[0048] Depending on the designed door panel dimensions, the prepreg is cut using an automatic cutting machine or manually.

[0049] Preferably, step S2 further includes using a tool to make the prepreg fit tightly against the mold, the tool including a pressure plate and a pressure roller.

[0050] Preferably, step S2 further includes heating the prepreg with a heat gun or an electric iron if the temperature is low, the prepreg is hard, and the adhesiveness is insufficient, before laying the prepreg.

[0051] Prepreg refers to epoxy resin and quartz fiber pre-impregnated into an uncured intermediate state. The main function of prepreg is to ensure mechanical properties while also providing good wave transmission performance. Combined with the subsequent functional layer (radar-absorbing fabric), this gives the door a certain degree of radar stealth capability.

[0052] Preferably, in step S4, the functional material is a wave-absorbing cloth, a shielding copper mesh, or a bulletproof plate.

[0053] Preferably, in step S6, the glass fiber cloth has the same thickness as the prepreg.

[0054] Preferably, in step S7, before laying the vacuum auxiliary material, a pre-formed silicone block is inserted into the weight reduction groove of the metal door frame to prevent resin from entering the groove, and the edge gap between the metal door frame and the door panel is checked, and glass fiber cloth or polyurethane foam blocks are filled according to the size of the gap to fill the gap.

[0055] The purpose of filling the gap between the metal door frame and the door panel with continuous fiberglass mat or foam is mainly to reduce weight (avoiding excessive resin filling) and to ensure better connection strength between the door panel and the metal door frame.

[0056] Vacuum bags, release films, breathable felts, and sealing strips are commonly used vacuum auxiliary materials in the resin-based composite materials industry. Vacuum bags are soft films made of plastic or nylon, used to seal the product within the mold by holding it in place or attaching it to the mold flange. Release films are also plastic films, typically laid between the product surface and the breathable felt (the same material as absorbent felt), used to separate the breathable felt from the mold. Release films come in perforated and non-perforated varieties; perforated release films allow excess resin in the product to permeate and be absorbed by the breathable felt, reducing the product's resin content. Breathable felt is a loose, soft material that absorbs excess resin while allowing air to pass through during the vacuuming process, preventing the vacuum bag from sticking too tightly to the product, causing air suffocation and affecting product compaction. Sealing strips primarily seal the vacuum bag, creating a completely sealed space for the product. All of the above vacuum auxiliary materials have a specific maximum temperature resistance rating, generally selected based on curing temperature parameters.

[0057] Vacuuming uses vacuum pressure to compact the prepreg layers. Compared to manual methods, it can compact the entire layer more evenly and without omissions, eliminating residual air and avoiding the risk of product defects.

[0058] The present invention also proposes a resin-based composite material door body, which is prepared by the molding method described above; the door body includes a door panel and a metal door frame, wherein the metal door frame covers the periphery of the door panel.

[0059] Example 1

[0060] This embodiment provides a molding method for a resin-based composite material door, including the following steps:

[0061] S1: Design the matching dimensions of the door panel and door frame, select the mold, and clean the mold with acetone, alcohol, or other cleaning agents to remove dirt and dust. After drying at room temperature, apply release agent to the mold. Generally, apply 5 coats to a new mold, with an interval of about 15 minutes between each coat. Wait 30 minutes after the last coat before laying down the release cloth.

[0062] S2: Two layers of epoxy quartz prepreg are laid on the mold after S1. The prepreg is cut using an automatic cutting machine. Vacuum auxiliary materials such as vacuum bag film, isolation film, breathable felt, and sealing strip are laid. Vacuum is drawn to further bond the prepreg tightly to the mold.

[0063] S3: A resin film is laid on the epoxy quartz prepreg after S2, and the processed PVC foam is laid on the resin film.

[0064] S4: Lay a layer of resin film and a layer of wave-absorbing cloth on the PVC foam in sequence, and then lay the processed polyurethane foam on the wave-absorbing cloth.

[0065] S5: Wrap two layers of continuous glass fiber felt around the metal embedded part, and then embed the metal embedded part into the set position on the polyurethane foam;

[0066] S6: Lay two layers of fiberglass cloth on the polyurethane foam to obtain the door panel layup;

[0067] S7: Wrap two layers of continuous fiberglass mat around the pre-processed metal door frame. Then, nest the metal door frame around the door panel layer. Insert pre-formed silicone blocks into the weight-reducing grooves of the metal door frame to prevent resin from entering. Check the gaps between the edges of the metal door frame and the door panel layer, and fill the gaps with fiberglass cloth or polyurethane foam blocks according to the size of the gaps. Then, lay out the vacuum auxiliary materials in the order of release cloth, guide net, and vacuum bag film, and set the glue inlet and outlet.

[0068] S8: Seal the vacuum bag film, establish the vacuum system, and maintain pressure. When the vacuum gauge reading is stable above 0.0095 MPa, inject resin;

[0069] When the resin has completely impregnated the product layup and is flowing out from the product edge or from the dispensing nozzle, stop pouring resin, but keep the vacuum pump running. Let it sit at room temperature for 8-12 hours to allow the resin to basically cure.

[0070] Once the resin has basically cured, turn off the vacuum, transfer the mold to the drying oven, and heat it at 50℃ for 2 hours and 80℃ for 4 hours to allow the resin to fully cure.

[0071] Once the resin has fully cured and cooled to room temperature, remove the vacuum auxiliaries and eject the product from the mold.

[0072] Use tools such as cutting machines and grinding machines to remove burrs and flash from the product, and polish the product surface in preparation for the next post-processing step.

[0073] The product undergoes subsequent processes such as drilling, assembly, and painting according to technical requirements.

[0074] The resin-based composite door body prepared in this embodiment is as follows: Figure 1 and 2 As shown, the resin-based composite door is lightweight, weighing more than one-third less than a metal door of the same size; and being a solid structure, it has better impact strength.

[0075] Composite functional materials in the middle of the door panel, such as radar-absorbing materials, bulletproof materials, and shielding materials, can achieve functions such as radar stealth, bulletproof, and electromagnetic shielding.

[0076] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A method of forming a resin-based composite door body, characterized by, The method comprises the following steps: S1: design the matching size of the door panel and the door frame, select a mold, and clean the mold with acetone and alcohol cleaning agent, remove dirt and dust, dry at room temperature, and then apply a mold release agent to the mold. Generally, new molds are applied 5 times, with an interval of 15 minutes each time. After the last application, wait for 30 minutes before laying the PTFE release cloth; S2: Lay two layers of epoxy quartz pre-impregnated material on the mold after S1. According to the designed size of the door panel, use an automatic cutting machine to cut and lay the vacuum auxiliary material, which includes a vacuum bag film, a separation film, a breathable felt, and a sealing rubber strip. Vacuumize and further adhere the pre-impregnated material tightly to the mold; S3: Lay a layer of resin adhesive film on the epoxy quartz pre-impregnated material after S2, and lay the processed PVC foam on the resin adhesive film; S4: Lay a layer of resin adhesive film and a layer of wave-absorbing cloth on the PVC foam in sequence, and then lay the processed polyurethane foam on the wave-absorbing cloth; S5: Wrap the metal embedded part with two layers of glass fiber continuous felt, and then embed the metal embedded part at the designated position on the polyurethane foam; S6: Lay two layers of glass fiber cloth on the polyurethane foam, which has the same thickness as the pre-impregnated material in step S2, to obtain a door panel layup; S7: Wrap the processed metal door frame with two layers of glass fiber continuous felt, then nest the metal door frame around the door panel layup, and put pre-formed silica gel blocks into the weight-reducing grooves of the metal door frame to prevent resin from entering. Check the gap between the edge of the metal door frame and the door panel layup, and fill the gap with glass fiber cloth or polyurethane foam blocks according to the size of the gap. Then lay the vacuum auxiliary material in the order of release cloth, flow guide net, and vacuum bag film, and set the glue inlet and outlet. S8: vacuum infusion resin, establish a vacuum system, pressure, when the vacuum table reading is stable more than 0.0095mpa, infusion resin; when the resin completely immersed product layer, from the product edge flow, or from the glue outlet, stop pouring resin, but keep the vacuum pump open; room temperature for 8 12 hours, wait for the resin to solidify; after the resin is completely cured and cooled to room temperature, remove the vacuum auxiliary material, and take the product out of the mold; use a cutting machine and a grinding machine to remove the flash burr of the product, polish the surface of the product, and prepare for the next step of post-processing; according to the technical requirements, the product is perforated, assembled and painted to obtain a resin-based composite material door body; The prepared shaped resin-based composite door body is light in weight, about 1 / 3 lighter than a metal door body of the same size; and has a solid structure with better impact strength. The door panel contains functional materials such as wave-absorbing materials, bulletproof materials, and shielding materials for radar stealth, bulletproof, and electromagnetic shielding.

2. The molding method according to claim 1, wherein Step S2 further comprises using tools to adhere the pre-impregnated material tightly to the mold, the tools including a pressing plate and a pressing roller.

3. The molding method according to claim 1, wherein Step S2 further comprises heating the pre-impregnated material with a hot air gun or an electric iron before laying the pre-impregnated material.

4. A resin-based composite door body, characterized by, Prepared by the molding method of any one of claims 1-3; the door body comprises a door panel and a metal door frame, and the metal door frame is wrapped around the door panel.

Images