Monomer shell preparation process

Abstract

The invention relates to the technical field of monomer shell preparation, and discloses a monomer shell preparation process which comprises the steps that a laminated board is laid on a mold bottom plate, and the laminated board comprises a sandwich board and skins located on the two sides of the sandwich board; the laminated board is covered with a vacuum bag, and the edge of the vacuum bag is bonded with the mold bottom plate; the space defined by the vacuum bag is vacuumized, a vacuum environment is formed for the follow-up heating and curing step of the laminated board, and external air is prevented from entering and influencing curing; and heating and curing the laminated board in the vacuum bag to fix the skins on the two sides with the sandwich board, and demolding the laminated board after cooling. According to the method, autoclave equipment is not needed to construct a vacuum environment and heat curing is not needed, so that the production cost is greatly reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of monomer shell preparation, and in particular to a monomer shell preparation process. Background Art

[0002] A composite monocoque, also known as a carbon fiber laminate body, consists of two skins, a sandwich layer, and adhesive film for bonding. The skins can be designed and laid up using a variety of reinforced fiber materials. The sandwich layer's layup requires mechanical testing to verify the rationality of the layup and process. Because the material preparation cycle can take up to five hours, it requires an autoclave to bake and vacuum the mold wrap. The high cost of autoclave equipment contributes to the high cost of monocoque production. Summary of the Invention

[0003] The invention discloses a monomer shell preparation process, which is used to reduce the monomer shell preparation cost.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] A monocoque manufacturing process includes: laying a laminate, comprising a sandwich panel and skins on either side of the sandwich panel, on a mold base; covering the laminate with a vacuum bag and bonding the edges of the vacuum bag to the mold base; evacuating the space enclosed by the vacuum bag to create a vacuum environment for the subsequent heating and curing steps of the laminate, preventing outside air from entering and affecting curing; heating and curing the laminate within the vacuum bag to secure the skins on both sides to the sandwich panel, and demolding the laminate after cooling. This process eliminates the need for autoclave equipment to create a vacuum environment and heat-curing, significantly reducing production costs.

[0006] Optionally, the heating and curing of the laminate on the mold bottom plate specifically includes: placing the laminate in an electric blower drying oven for baking and heating.

[0007] Optionally, while evacuating the space enclosed by the vacuum bag, the air leakage at the edge of the vacuum bag is checked based on the residual air in the vacuum bag, and the leaking part of the vacuum bag is additionally bonded and fixed to the mold bottom plate.

[0008] Optionally, before covering the vacuum bag on the laminate, the method further includes: covering the laminate with a waterproof sealing bag, and bonding the edge of the waterproof sealing bag to the mold bottom plate.

[0009] Optionally, before covering the waterproof sealing bag on the laminate, the method further comprises: covering the laminate with a non-porous isolation film.

[0010] Optionally, the vacuum bag is made of polytetrafluoroethylene, the waterproof sealing bag is made of polyetheretherketone, and the non-porous isolation membrane is made of polytetrafluoroethylene.

[0011] Optionally, before covering the laminate with a waterproof sealing bag, the method further includes: laying a vacuum conduit at a preset position along the edge of the vacuum bag, wherein the vacuum conduit has exhaust holes spaced apart along the length direction; and evacuating the space enclosed by the vacuum bag specifically includes: evacuating the vacuum conduit using a vacuum pump.

[0012] Optionally, laying the vacuum conduit along a preset position on the edge of the vacuum bag specifically includes: connecting the vacuum pump to two vacuum conduits through a three-way conduit, and laying the two vacuum conduits along the preset position on the edge of the vacuum bag in opposite directions.

[0013] Optionally, the upper skin material of the sandwich layer is UD-100T700 unidirectional 12k prepreg cloth, the lower skin material is Twill-100 T300 plain 3k prepreg cloth, and the base material of the sandwich layer is 25mm or 20mm honeycomb aluminum; the heating and curing of the laminate in the vacuum bag specifically includes: heating from room temperature to 75°C to 85°C in 25 to 35 minutes, and maintaining for 55 to 65 minutes; heating from room temperature to 145 to 155°C in 35 to 45 minutes, and maintaining for 90 to 100 minutes; heating from room temperature to 115 to 125°C in 15 to 25 minutes, and maintaining for 55 to 65 minutes; and naturally cooling to room temperature.

[0014] Optionally, after laying the laminate on the mold base plate, the method further includes: pre-embedding a bracket at the opening position of the mold base plate, or fixing a lifting lug. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A schematic diagram of the vacuum bag after laying in the monomer shell preparation process provided in an embodiment of the present application;

[0016] Figure 2 A monomer shell produced by the monomer shell preparation process provided in an embodiment of the present application;

[0017] Figure 3 It represents the temperature curve of heating and curing in the monomer shell preparation process provided in the embodiment of the present application. DETAILED DESCRIPTION

[0018] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. 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 making creative efforts are within the scope of protection of the present invention.

[0019] refer to Figure 1 The single shell preparation process provided by the embodiment of the present application includes: laying a laminate 105 on a mold base 101, the laminate 105 including a sandwich panel and skins on both sides of the sandwich layer, the upper skin length can be longer than the lower skin, so as to leave a margin for later cutting; covering the laminate 105 with a vacuum bag 103, and bonding the edge of the vacuum bag 103 to the mold base 101, specifically, bonding with a high-temperature resistant sealant; evacuating the space surrounded by the vacuum bag 103 to absorb the air on the surface of the laminate 105, forming a vacuum environment for the subsequent heating and curing step of the laminate 105, and preventing external air from entering and affecting the curing; heating and curing the laminate 105 in the vacuum bag 103 to fix the skins on both sides to the sandwich panel, and demolding the laminate 105 after cooling to form a primary mold. At this time, the primary mold blank can be cut and subjected to water-grinding finishing surface treatment, such as filling and grinding with materials such as resin to form a single shell (reference Figure 2 ). As described above, there is no need to use autoclave equipment to create a vacuum environment and heat curing, which greatly reduces production costs.

[0020] In one specific embodiment, the laminate 105 on the mold base 101 is heated and cured by placing the laminate 105 in an electric blower drying oven for baking and heating. The laminate 105, which is contained in a vacuum environment by the vacuum bag 103 and the mold base 101, can be directly placed in the electric blower drying oven for heating and curing, with specific temperatures set at different time periods. The cost of an electric blower drying oven is significantly lower than that of an autoclave, while achieving better curing results.

[0021] For example, reference Figure 3In one specific embodiment, the upper skin material of the sandwich layer is UD-100T700 unidirectional 12k prepreg, the lower skin material is Twill-100 T300 plain weave 3k prepreg, and the core layer matrix material is 25mm or 20mm honeycomb aluminum. The laminate 105 within the vacuum bag 103 is heat-cured, specifically by heating from room temperature to 75°C to 85°C over a period of 25 to 35 minutes and holding for 55 to 65 minutes; heating from room temperature to 145°C to 155°C over a period of 35 to 45 minutes and holding for 90 to 100 minutes; heating from room temperature to 115°C to 125°C over a period of 15 to 25 minutes and holding for 55 to 65 minutes; and then naturally cooling to room temperature. The monocoque formed using these heat-curing conditions exhibits high-temperature resistance, fire resistance, excellent toughness, and stress and tension resistance. A stopwatch can be used to monitor the curing process for precise control of the heating time.

[0022] The relevant parameters of the electric blower drying oven and vacuum pump can be referred to Table 1. According to the pressure law required for the simulated autoclave process, the maximum pressure of the XD-020 rotary vane vacuum pump is set to 200Pa.

[0023] Electric blower drying oven XD-020 rotary vane vacuum pump Model: XL-101-8 Ultimate vacuum: 200Pa Power: 30kw Motor speed: 2800 rpm / min Maximum temperature: 300°C Motor power: 0.75KW

[0024] Table 1

[0025] In one specific embodiment, while the space enclosed by the vacuum bag 103 is being evacuated, the edges of the vacuum bag 103 are inspected for air leaks based on any remaining air within the bag. The leaking areas of the vacuum bag 103 are then re-bonded and secured to the mold base 101. This prevents a loose seal around the edges of the vacuum bag 103, which could lead to air entering during the subsequent curing process, disrupting the vacuum environment and affecting the performance of the monomer shell. During the evacuation process, air bubbles between the layers can be squeezed to completely expel the air.

[0026] In a specific embodiment, before covering the vacuum bag 103 on the laminate 105, it also includes: covering the laminate 105 with a waterproof sealing bag 102, and bonding the edge of the waterproof sealing bag 102 to the mold bottom plate 101. The waterproof sealing bag 102 can effectively block water vapor from the outside to prevent water vapor from affecting the curing and molding of the laminate 105.

[0027] In a specific embodiment, before covering the waterproof sealing bag 102 on the laminate 105, it also includes: covering the laminate 105 with a non-porous isolation film 104, which is conducive to separating the laminate 105 and the waterproof sealing bag 102 during demoulding to avoid adhesion.

[0028] The vacuum bag 103 can be made of polytetrafluoroethylene, which has excellent air barrier properties and is relatively low in cost. The sealing bag 102 can be made of polyetheretherketone, which has excellent water vapor barrier properties and is relatively low in cost. The non-porous isolation membrane 104 can also be made of polytetrafluoroethylene, which is low in cost and easily separated from the waterproof sealing bag 102. Furthermore, all of the above materials are heat-resistant to avoid damage during heat curing.

[0029] In one specific embodiment, before covering the laminate 105 with the waterproof sealing bag 102, the process further includes: laying a vacuum conduit at a predetermined position along the edge of the vacuum bag 103, the vacuum conduit having extraction holes spaced apart along its length; and evacuating the space enclosed by the vacuum bag 103, specifically by using a vacuum pump to evacuate the vacuum conduit. Because the extraction holes are spaced apart along its length, the vacuum conduit effectively extracts air from the edges of the vacuum bag 103. Furthermore, extracting air from the edges toward the center facilitates the removal of clean air.

[0030] In one specific embodiment, vacuum conduits are laid along predetermined locations along the edge of the vacuum bag 103. This involves connecting a vacuum pump to two vacuum conduits via a three-way conduit. These two vacuum conduits are then laid in opposite directions along the predetermined locations along the edge of the vacuum bag 103 to increase vacuuming efficiency. Furthermore, a higher-powered vacuum pump can be used to extract air. Openings for the vacuum conduits can be reserved before laying out the vacuum bag 103 and waterproof sealing bag 102.

[0031] In a specific embodiment, after the laminate 105 is laid on the mold base plate 101, the method further includes: pre-embedding brackets or fixing lugs at the openings of the mold base plate 101, so as to facilitate the connection and fixing of other structures to the monocoque via the pre-embedded brackets or lugs.

[0032] Among them, when cutting the prepreg, tools such as scissors and a level ruler can be used, which is low in cost.

[0033] The above process reduces the preparation cost while meeting the physical property requirements of the monomer shell.

[0034] Obviously, those skilled in the art may make various changes and modifications to the embodiments of the present invention without departing from the spirit and scope of the present invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims and their equivalents, the present invention is intended to include such modifications and variations.

Claims

1. A process for preparing a monomer shell, characterized in that: include: Laying a laminate on a mold bottom plate, wherein the laminate comprises a sandwich panel and skins located on both sides of the sandwich layer; Cover the laminate with a vacuum bag and bond the edge of the vacuum bag to the mold base; Vacuum the space surrounded by the vacuum bag; The laminate is heated and cured within the vacuum bag and demoulded after cooling.

2. The process for preparing a monomer shell according to claim 1, characterized in that: The step of heating and curing the laminate on the mold bottom plate specifically includes: The laminate is placed in an electric blower drying oven for baking and heating.

3. The process for preparing a monomer shell according to claim 1, characterized in that: While the space enclosed by the vacuum bag is being evacuated, the air leakage at the edge of the vacuum bag is checked based on the remaining air in the vacuum bag, and the leaking part of the vacuum bag is supplementally bonded and fixed to the mold bottom plate.

4. The process for preparing a monomer shell according to claim 1, characterized in that: Before covering the laminate with a vacuum bag, the method further includes: The laminate is covered with a waterproof sealing bag, and the edge of the waterproof sealing bag is bonded to the mold bottom plate.

5. The process for preparing a monomer shell according to claim 4, characterized in that: Before covering the laminate with a waterproof sealing bag, it also includes: The laminate is covered with a non-porous release film.

6. The process for preparing a monomer shell according to claim 5, characterized in that: The material of the vacuum bag is polytetrafluoroethylene, the material of the waterproof sealing bag is polyetheretherketone, and the material of the non-porous isolation membrane is polytetrafluoroethylene.

7. The process for preparing a monomer shell according to claim 4, characterized in that: Before covering the laminate with a waterproof sealing bag, it also includes: Laying a vacuum conduit at a preset position along the edge of the vacuum bag, wherein the vacuum conduit has air extraction holes spaced apart along the length direction; The step of evacuating the space enclosed by the vacuum bag specifically includes: Use a vacuum pump to evacuate the vacuum tube.

8. The process for preparing a monomer shell according to claim 7, characterized in that: Lay the vacuum conduit at the preset position along the edge of the vacuum bag, including: Connect the vacuum pump to the two vacuum tubes through a three-way tube, and lay the two vacuum tubes in opposite directions at preset positions along the edge of the vacuum bag.

9. The process for preparing a monomer shell according to claim 7, characterized in that: The upper skin material of the sandwich layer is UD-100T700 unidirectional 12k prepreg fabric, the lower skin material is Twill-100 T300 plain weave 3k prepreg fabric, and the base material of the sandwich layer is 25mm or 20mm honeycomb aluminum; The heating and curing of the laminate in the vacuum bag specifically includes: Heat from room temperature to 75°C to 85°C over a period of 25 to 35 minutes and hold for 55 to 65 minutes; Heating from room temperature to 145°C to 155°C over a period of 35 to 45 minutes and holding for 90 to 100 minutes; Heat from room temperature to 115°C to 125°C over a period of 15 to 25 minutes and hold for 55 to 65 minutes; Cool naturally to room temperature.

10. The process for preparing a monomer shell according to claim 1, characterized in that: After the laminate is laid on the mold bottom plate, the method further comprises: Embed brackets in the openings of the mold base, or install fixed lugs.

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