Method for pre-forming wall panel

Abstract

A method for pre-forming a wall panel, comprising the following steps: laying a flat sheet flat and placing it on a pre-forming tool, such that both ends of the flat sheet extend into the grooves at both ends of the pre-forming tool respectively; laying a vacuum bag film over the flat sheet such that the vacuum bag film covers the flat sheet; connecting the vacuum bag film to the edges of the forming tool, sealing the pre-forming tool; transferring the pre-forming tool and the flat sheet to a heating apparatus for heating; evacuating the interior of the pre-forming tool so that the flat sheet conforms to the pre-forming tool, completing the pre-forming. The wall panel pre-forming method provided herein can be used to prevent the dimensions and structure of the flat sheet from being limited by the pre-forming apparatus, thereby improving production efficiency.

Description

A method for preforming wall panels Cross-referencing

[0001] This application claims priority to Chinese application No. 2024119413599, filed on December 25, 2024. The contents of the above application are incorporated herein by reference. Technical Field

[0002] This application relates to material forming, and more particularly to a method for preforming wall panels. Background Technology

[0003] In the aerospace manufacturing industry, composite materials, with their superior comprehensive properties, have replaced most metal materials. With the widespread application of composite materials, automated layup technology for composite parts has developed rapidly, gradually replacing traditional manual layup methods. To continuously improve the quality of finished parts, preforming has become a crucial step in the entire molding process. Preforming technology can produce L-shaped, C-shaped, and Ω-shaped composite preforms; however, it is difficult to achieve a preforming technology that can ensure both the quality of the preforms and production efficiency for manufacturing more complex shell-like products.

[0004] Currently, complex-shaped products such as shells are mainly formed using hand-layout molding, automated fiber and tape laying molding, and thermal insulation film preforming. Among them, thermal insulation film preforming generally involves first laying a flat sheet, and then using a single-layer or double-layer diaphragm for preforming. Due to the limitations of thermal insulation film equipment, the depth or arch height of the parts should not be too large, and the radius (R) corners of the products will inevitably be subjected to out-of-plane normal pressure and the material's own adhesive force during the preforming process, resulting in failure modes. The main failure modes are surface bridging, in-plane buckling of fibers, and out-of-plane wrinkling, which reduces production efficiency.

[0005] Therefore, it is necessary to provide a new method for preforming wall panels to solve the aforementioned problems existing in the prior art. Summary of the Invention

[0006] Technical issues

[0007] The technical problem to be solved by this application is to provide a wall panel preforming method that can avoid the limitation of the size and structure of flat sheet material by preforming equipment and improve production efficiency in processing wall panels.

[0008] Technical solution

[0009] To solve the above-mentioned technical problems, according to an embodiment of this application, a pre-forming method for a wall panel is provided, comprising the following steps: laying the flat sheet flat and placing it on the pre-forming fixture, such that both ends of the flat sheet extend to the grooves at both ends of the pre-forming fixture; laying a vacuum bag film on the flat sheet, so that the vacuum bag film covers the flat sheet; connecting the vacuum bag film to the edge of the pre-forming fixture to seal the pre-forming fixture; transferring the pre-forming fixture and the flat sheet to a heating device for heating; and evacuating the interior of the pre-forming fixture to make the flat sheet adhere to the pre-forming fixture, thereby completing the pre-forming process.

[0010] Optionally, the panel preforming method may further include: before placing the flat sheet on the preforming fixture, applying a release film to the preforming fixture, such that both ends of the release film extend to the grooves at both ends of the preforming fixture and connect with the edges of the preforming fixture.

[0011] Optionally, the panel preforming method may further include: before laying the vacuum bag film on the flat sheet, laying a peelable fabric on the flat sheet so that the peelable fabric covers the flat sheet.

[0012] Optionally, the preforming method for the wall panel may further include: after laying the vacuum bag film on the flat sheet, pleating the end of the vacuum bag extending into the groove.

[0013] Optionally, the panel preforming method may further include: after flattening the flat sheet and placing it on the preforming fixture, setting multiple thermocouples in the area of ​​the flat sheet to be deformed to measure the temperature of the area of ​​the flat sheet to be deformed.

[0014] Optionally, the step of setting multiple thermocouples in the area to be deformed on the flat sheet includes: setting the thermocouples on both the front and back surfaces of the flat sheet, so that multiple thermocouples are placed in the area to be deformed on the flat sheet; fixing the thermocouples with pressure-sensitive tape; and using the thermocouples to measure the temperature of the front and back surfaces of the flat sheet respectively.

[0015] Optionally, the panel preforming method may further include: heating the flat sheet before evacuating the interior of the preforming fixture in the heating equipment; and evacuating the preforming fixture through a vacuum nozzle on the preforming fixture while evacuating the interior of the preforming fixture in the heating equipment, maintaining the preforming fixture at a set temperature until the flat sheet is initially shaped.

[0016] Optionally, heating the flat sheet includes: uniformly heating the flat sheet to above 50°C and maintaining it at above 50°C for at least 10 minutes.

[0017] Optionally, the step of evacuating the preforming fixture through the vacuum nozzle on the preforming fixture and maintaining the preforming fixture at a set temperature until the flat sheet is initially shaped includes: evacuating the preforming fixture and maintaining it at a temperature above 50°C for more than 20 minutes when the internal air pressure of the preforming fixture is -15 kPa or below; and evacuating the preforming fixture again and maintaining it at a temperature above 60°C for more than 5 minutes when the internal air pressure of the preforming fixture is below -80 kPa.

[0018] Optionally, the step of fitting the flat sheet into the preforming fixture to complete the preforming includes: cooling the flat sheet to below 50°C and keeping the flat sheet in a vacuum state for more than 5 minutes to preform the flat sheet.

[0019] Beneficial effects

[0020] Compared with the prior art, the technical solution of this application can achieve at least the following beneficial effects:

[0021] By adopting the above technical solution, since the two ends of the flat sheet extend to the grooves at both ends of the preforming tooling, when the shape of the flat sheet changes, it can deform along the sidewall of the groove. At least one sidewall of the groove is arc-shaped, which allows the flat sheet to transition smoothly, thus adapting to parts with large depths or high arches. At the same time, the vacuum bag film covers the flat sheet, and during the vacuuming process, the vacuum bag film shrinks, providing a uniform force to the flat sheet, thereby reducing surface bridging, fiber in-plane buckling, and out-of-plane wrinkles, thus improving the production efficiency of the wall panel. In addition, it can realize the automated forming of large-size and high-curvature deep U-shaped wall panels, with high process efficiency and guaranteed forming quality. It avoids the limitation of the size and curvature structure of the parts by the equipment, reducing the forming cost of the parts. At the same time, the method has simpler mold requirements, reducing mold design and manufacturing costs. Using ordinary vacuum bags and curing ovens, without the need for heat insulation film equipment or imported high-elongation vacuum bag films, the heat insulation film preforming effect can be achieved, reducing the occurrence of failure modes after preforming. Attached Figure Description

[0022] Figure 1 is a flowchart of a wall panel preforming method according to an embodiment of this application;

[0023] Figure 2 is a schematic diagram of the preforming tooling in a wall panel preforming method according to an embodiment of this application;

[0024] Figure 3 is a schematic diagram showing the positions of the release film and pressure-sensitive adhesive tape in a wall panel preforming method according to an embodiment of this application.

[0025] Figure 4 is a schematic diagram of the thermocouple installation position on the preforming tooling in a panel preforming method according to an embodiment of this application.

[0026] Figure label:

[0027] 100. Frame body; 110. Boss; 120. Groove; 130. Molded panel; 140. Vacuum nozzle base; 200. Isolation membrane; 300. Pressure-sensitive tape; 410. First installation position; 420. Second installation position. Detailed Implementation

[0028] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. Unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by those skilled in the art to which this application pertains. The words "comprising" and similar terms used herein mean that the element or object preceding the word covers the element or object listed after the word and its equivalents, but does not exclude other elements or objects.

[0029] In the aerospace manufacturing industry, composite materials, with their superior comprehensive properties, have replaced most metal materials. With the widespread application of composite materials, automated layup technology for composite parts has developed rapidly, gradually replacing traditional manual layup methods. To continuously improve the quality of finished parts, preforming has become a crucial step in the entire molding process. Preforming technology can produce L-shaped, C-shaped, and Ω-shaped composite preforms; however, it is difficult to achieve a preforming technology that can ensure both the quality of the preforms and production efficiency for manufacturing more complex shell-like products.

[0030] Currently, complex-shaped products such as shells are mainly produced using hand-layout molding, automated fiber and tape laying molding, and thermal insulation film preforming. Hand-layout molding is inefficient, labor-intensive, and difficult to guarantee in terms of molding quality. While automated fiber and tape laying molding are efficient and facilitate automated production, they suffer from complex mold manufacturing, high equipment costs, and limitations in manufacturing parts with large dimensions and curvature. Thermal insulation film preforming typically involves laying a flat sheet first, followed by preforming with a single or double-layer diaphragm. Due to limitations in thermal insulation film equipment, the depth or arch height of the parts cannot be too large, and the radius (R) corners of the product inevitably experience out-of-plane normal pressure and material adhesion during preforming, leading to failure modes, primarily surface bridging, in-plane fiber buckling, and out-of-plane wrinkling.

[0031] Especially for the preforming of large-size deep U-shaped wall panels, the large depth of the parts limits the use of thermal insulation film equipment. Therefore, this application adopts a process method for preforming large-size deep U-shaped wall panels using a curing oven vacuum process. The design of simple tooling avoids the size and structure of the parts being limited by the equipment. It eliminates the need to use imported high-elongation vacuum bags and films, adjusts the process, reduces the occurrence of failure modes after preforming, and improves the forming quality of the web area and R-corners of the deep U-shaped wall panels.

[0032] In view of the above, this application provides a preforming method for wall panels, which is applicable to U-shaped wall panels, C-shaped wall panels, or other wall panels with suitable shapes, especially wall panels with large arch heights. In this embodiment, the preforming of a large-size deep U-shaped wall panel is used as an example.

[0033] The specific embodiments of this application will be further described in detail below with reference to the accompanying drawings.

[0034] Referring to Figure 1, embodiments of this application provide a preforming method for wall panels, wherein the method is applicable to large-size deep U-shaped wall panels, and includes the following steps:

[0035] S100, Prepare the flat fixture, lay the flat sheet on the flat fixture, so that the flat sheet is in a flat state, place the flat sheet on the preforming fixture, so that both ends of the flat sheet extend to the grooves 120 at both ends of the preforming fixture.

[0036] S200. Lay a vacuum bag film on the flat sheet to cover the flat sheet;

[0037] S300. Connect the edge of the vacuum bag film to the edge of the forming fixture so that the vacuum bag film seals the preforming fixture. At this time, the flat sheet is placed between the preforming fixture and the vacuum bag film.

[0038] S400: Transfer the preformed tooling and flat sheet together to the heating equipment for heating.

[0039] S500: In the heating equipment, the inside of the pre-forming fixture is evacuated through a vacuum nozzle to make the flat sheet fit into the pre-forming fixture, and then the flat sheet is cured to pre-form the flat sheet.

[0040] In some embodiments, the function of the flat plate tooling is to facilitate the flattening of the flat sheet material. The flat plate tooling is prior art and will not be described in detail here.

[0041] The preforming fixture includes a frame body 100. Referring to Figure 2, the frame body 100 is hollow, with an open top, forming a shell shape. A boss 110 is integrally formed on the inner bottom of the frame body 100, with a gap between the top of the boss 110 and the top of the frame body 100. This prevents the flat sheet from protruding from the frame body 100 when placed inside. The boss 110 also creates two grooves 120 inside the frame body 100, located at both ends. A forming panel 130 is provided on the boss 110 of the frame body 100. Panel 130 is used to place flat sheet material, thereby facilitating the processing of the flat sheet material. In addition, the frame body 100 is also provided with a vacuum nozzle base 140 for vacuuming, on which a vacuum nozzle is installed. In this embodiment, the vacuum nozzle base 140 is located at two diagonally opposite corners of the boss 110. In the above-mentioned S100, placing the flat sheet material in a flat state on the preforming fixture actually refers to placing the flat sheet material in a flat state on the forming panel 130. In the above-mentioned S300, connecting the edge of the vacuum bag film with the edge of the forming fixture, so that the vacuum bag film seals the preforming fixture, actually refers to connecting the edge of the vacuum bag film with the edge of the frame body 100, so that the interior of the frame body 100 is sealed.

[0042] In some embodiments, air-guiding material needs to be pasted in the groove 120 and in the area on the boss 110 where the molded panel 130 is not provided. The air-guiding material can be breathable felt, polyester fiber mesh, or non-woven fabric, etc., as long as it can achieve air permeability and air guidance.

[0043] In some embodiments, the process of initially shaping and preforming the flat sheet mainly relies on the restriction of the groove 120 and the arc-shaped sidewall of the groove 120. Therefore, the size and structure of the flat sheet can be avoided from being restricted by the preforming tooling, thereby improving production efficiency.

[0044] In this embodiment, referring to Figures 1 and 3, before placing the flat sheet on the preforming fixture, a release film 200 is also laid on the preforming fixture, and the two ends of the release film 200 extend to the grooves 120 at both ends of the preforming fixture.

[0045] In some embodiments, mimicking the effect of a double-diaphragm configuration, the separator is fixed and tightened on a preforming fixture to support the weight of the flat sheet. In some more specific embodiments, a transparent separator is preferred.

[0046] Specifically, the release liner 200 is mainly used to separate the flat sheet material from the molded panel 130, facilitating the subsequent demolding process. The release liner 200 must at least cover the molded panel 130. During the installation of the release liner 200, pressure-sensitive adhesive tape 300 is used to connect the release liner 200 to the edge of the pre-formed fixture, so that the release liner 200 is laid flat on the molded panel 130. In some embodiments, before applying the pressure-sensitive adhesive tape 300, the edges of the pre-formed fixture and the surface of the release liner 200 need to be cleaned to reduce the pressure of the adhesive tape 300 against the release liner 200 or the pre-formed fixture. The possibility of edge detachment; in some embodiments, the release membrane 200 covers part of the groove 120. The release membrane 200 helps to maintain the smoothness of the composite material surface and prevent defects on the mold surface from being transferred to the composite material. The release membrane 200 can be selected from polyethylene (PE) film, polypropylene (PE) film, polyethylene terephthalate (PET) film, polyimide (PI) film, polytetrafluoroethylene (PTFE) film, ethylene-vinyl acetate copolymer (EVA) film, silicone rubber film, etc. In actual use, different films can be selected according to different needs.

[0047] In some embodiments, the connection between the separator 200 and the preforming fixture can be achieved not only by connecting with pressure-sensitive tape 300, but also by fixing with clamps or adhesives. There are no restrictions on this method, so that the separator 200 can be connected to the preforming fixture to prevent the separator 200 from collapsing and wrinkling during the heating stage. At the same time, compared with the prior art, this method does not require heat separator equipment or imported high-elongation vacuum bag film to achieve the heat separator preforming effect. In addition, the economic benefits are improved by replacing the equipment.

[0048] In some embodiments, the preforming tooling is also provided with positioning elements. Specifically, the positioning elements are provided on the boss 110 of the frame body 100. Multiple positioning elements are provided and are evenly distributed on the boss 110. During the placement of the flat sheet, the edge of the flat sheet contacts the edge of the positioning element, thereby limiting the position of the flat sheet on the boss 110 and reducing the possibility of the flat sheet shifting.

[0049] In some embodiments, the preformed tooling is made entirely of aluminum alloy. Aluminum alloy has a low density, making the preformed tooling lightweight and easy to handle and operate. At the same time, aluminum alloy has high strength, which can ensure that the tooling maintains its shape and size stability during operation. In addition, aluminum alloy has good corrosion resistance, making it suitable for use in a variety of environments and extending the service life of the tooling.

[0050] In some embodiments, the molded panel 130 is made of a material with low thermal conductivity. Specifically, the material with low thermal conductivity can be polyimide (PI) film, polyphenylene sulfide (PPS), polyetherimide (PEI), epoxy resin laminate, silicone rubber, polyurethane foam, or phenolic resin laminate, etc. There are no restrictions on this, as long as it can meet the requirement of reducing heat transfer. The purpose of choosing a material with low thermal conductivity is to reduce the heat transfer to the flat sheet through the pre-forming tooling, thereby controlling the heating rate and curing process of the flat sheet and avoiding deformation or damage to the flat sheet due to excessive heating.

[0051] In this embodiment, before laying the vacuum bag film on the flat sheet, a peelable fabric needs to be laid on the flat sheet. The peelable fabric must at least cover the flat sheet. The peelable fabric is mainly used to provide an easy-to-peel surface to protect the cured wall panel surface from contamination or damage, and also facilitates subsequent processing. In addition, during the curing process, the peelable fabric needs to have a certain strength to withstand certain pressure and operation, and is not easy to break when peeled.

[0052] In some embodiments, the peelable fabric can be selected from polyester nonwoven fabric, glass fiber reinforced polyester or nylon fabric, Teflon (PTFE) coated glass fiber fabric, polytetrafluoroethylene (PTFE) film, etc. In actual use, different films can be selected according to different needs. It can be fixed on the flat sheet with a small amount of adhesive, or the peelable fabric can be pressed on the mold or composite material surface under vacuum without additional adhesive.

[0053] In this embodiment, after laying the vacuum bag film on the flat sheet, it is also necessary to pleat the end of the vacuum bag that extends to the groove 120.

[0054] In some embodiments, the more pleats there are, the better the effect of vacuuming in the later stage. Therefore, in this embodiment, the number of pleats is not limited. Pleats are made according to actual needs during use to prevent the vacuum bag from becoming hollow when it is tightened. In addition, the pleating process should ensure that the pleats are uniform, neat, and without damage or excessive deformation. After the pleats are made, the edge of the vacuum bag film should be able to connect with the edge of the frame body 100 to ensure sealing.

[0055] In some embodiments, the vacuum bag film is pleated by hand. Specifically, the ends of the vacuum bag film can be folded by hand at certain intervals and widths to form fan-shaped pleats or multiple parallel pleats; or the edges of the vacuum bag film can be pinched by hand to form irregular pleats.

[0056] In some embodiments, the vacuum bag film is pleated by mechanical pleating. Specifically, a creasing machine can be used to press regular creases on the edge of the vacuum bag film and then fold it; or a specialized pleating device can be used to create uniform pleats on the vacuum bag film.

[0057] In some embodiments, the vacuum bag film is pleated by a heat pleating method. Specifically, a heat press tool can be used to heat the vacuum bag film to soften it before folding, and the pleat shape can be fixed after cooling; or a heat gun can be used to locally heat the vacuum bag film to soften it before folding.

[0058] More specifically, the purpose of pleating is to ensure that the vacuum bag film can fully conform to the shape of the workpiece during the vacuuming process. In addition, the following points should be noted when pleating: the width and spacing of the pleats should be appropriate to ensure that the vacuum bag film can be evenly adhered to the workpiece; avoid excessive pleating to avoid affecting the sealing performance of the vacuum bag; ensure that the vacuum bag film is not damaged during the pleating process to avoid affecting its sealing and strength; and rationally design the position and number of pleats according to the shape of different workpieces and the deformation during the curing process.

[0059] After the flat sheet is laid flat and placed on the preforming fixture, the process also includes:

[0060] Multiple thermocouples are installed in the area of ​​the flat sheet to be deformed to measure the temperature of the area.

[0061] Specifically, thermocouples measure the temperature of the area to be deformed on the flat sheet, specifically at the radius (R-corner). Since the R-corner is an area where temperature gradients may occur on the component, and heat conduction may be uneven in these areas, thermocouples help monitor and ensure a uniform temperature distribution throughout the component. Furthermore, the shape of the R-corner area may cause the heat conduction rate to differ from that of the planar area. Thermocouples can provide specific data on these differences, allowing for adjustments to the heating process.

[0062] In some embodiments, the vacuuming rate during subsequent processing is adjusted in real time based on the temperature feedback from the thermocouple, that is, the process is adjusted in real time to ensure that the area of ​​the flat sheet to be deformed is always under stable stress, thereby reducing the occurrence of failure modes after preforming.

[0063] In some embodiments, multiple thermocouples are provided in the area to be deformed of the flat sheet. Specifically, thermocouples are provided on both the front and back surfaces of the flat sheet. Referring to Figure 4, the first mounting position 410 is the mounting position of the thermocouple on the front side of the flat sheet, and the second mounting position 420 is the mounting position of the thermocouple on the back side of the flat sheet.

[0064] In some embodiments, multiple thermocouples are respectively installed at the first installation position 410 and the second installation position 420, so that the multiple thermocouples are placed in the area of ​​the flat sheet to be deformed, and the thermocouples are fixed by pressure-sensitive adhesive tape 300 so that the position of the thermocouples will not move; at the same time, the thermocouples are used to measure the temperature of the front and back surfaces of the flat sheet respectively.

[0065] Specifically, in this embodiment, four thermocouples are selected, with two thermocouples located on the front of the flat sheet and the remaining two thermocouples located on the back of the flat sheet. In addition, the two thermocouples on the same side are set at an angle, that is, the four thermocouples can form a rectangle together. Among the four thermocouples, the two thermocouples set at opposite angles are located on the same side of the flat sheet.

[0066] In some embodiments, the thermocouple is fixed by clamps, bolts, or welding; there are no limitations, as long as the thermocouple can detect the temperature of the area to be deformed on the flat sheet. At the same time, depending on the material of the flat sheet, factors such as the type of thermocouple, measurement environment, temperature range, geometry of the fixing position, and whether long-term monitoring is required need to be considered to ensure the stability and measurement accuracy of the thermocouple.

[0067] In this embodiment, before evacuating the interior of the preforming fixture in the heating equipment, it is necessary to heat the flat sheet to preheat it. When evacuating the interior of the preforming fixture in the heating equipment, it is necessary to evacuate the preforming fixture through the vacuum nozzle on the preforming fixture to keep the preforming fixture at the set temperature until the flat sheet is initially shaped.

[0068] Specifically, preheating helps to bring the internal and external temperatures of the material into a more uniform state, thereby reducing internal stress caused by temperature gradients. This is especially true for some metallic materials, where preheating can improve their plasticity, making them easier to deform without breaking during subsequent forming or processing. At the same time, preheating ensures that the flat sheet reaches a specific temperature before processing, thus guaranteeing the quality of the processed flat sheet.

[0069] In some embodiments, the heating device is a curing oven.

[0070] In some embodiments, the use of a curing oven avoids the investment and operating costs of expensive thermal insulation film equipment; while thermal insulation film equipment typically requires complex molds and has high equipment costs, the curing oven is relatively simple and economical; the curing oven can accommodate the preforming of larger and deeper curvature parts, while thermal insulation film equipment, due to technical limitations, has certain limitations on the depth or arch height of parts and is not suitable for the preforming of large-sized deep U-shaped panels and other parts; in addition, the vacuum process of the curing oven can reduce failure modes after preforming, such as surface bridging, fiber in-plane buckling, and out-of-plane wrinkling, which are common failure modes in the thermal insulation film preforming process; the process using the curing oven has simpler mold requirements, reducing mold design and manufacturing costs, while thermal insulation film equipment usually requires more complex mold designs; the curing oven process can achieve automated preforming, improving production efficiency, while the thermal insulation film process involves more manual operation and is less efficient; the curing oven process does not require the use of imported high-elongation vacuum bags, and ordinary vacuum bags can be used, reducing material costs and also reducing preforming failures caused by material problems.

[0071] In some more specific embodiments, the thermal diaphragm equipment may be unsuitable if the depth of the part exceeds the extension capacity of the diaphragm or the effective range of the heating system. For example, if the depth of the part exceeds tens to hundreds of millimeters, such as 500 mm, it may exceed the processing capacity of some thermal diaphragm equipment. For components with highly arched structures, the thermal diaphragm equipment may not provide sufficient pressure to maintain close contact between the diaphragm, the mold, and the material, thus affecting the preforming effect. For large-sized components, such as those exceeding the width or length of the thermal diaphragm equipment's worktable, the thermal diaphragm equipment may also be unsuitable. In this solution, the preforming fixture works in conjunction with the curing oven and uses a vacuum nozzle to create a vacuum, providing sufficient pressure to maintain close contact between the diaphragm, the mold, and the material. Furthermore, the preforming fixture does not limit the size of the flat sheet material, enabling the processing of parts with depths ranging from tens to hundreds of millimeters.

[0072] In some embodiments, the heating device may also be an autoclave or oven, primarily designed to meet the heating requirements of flat sheet materials.

[0073] In some embodiments, the preformed tooling and the flat sheet are transferred to a heating device, and the heating device is controlled to heat up or keep warm so that the temperature inside the heating device is the required temperature to heat or keep warm the flat sheet.

[0074] In some embodiments, the flat sheet is heated at a uniform rate to above 50°C and maintained at a temperature above 50°C for more than 10 minutes.

[0075] In some more specific embodiments, the process of heating the flat sheet includes heating the flat sheet to 65°C at a heating rate of 3°C / min and holding the flat sheet at 65°C for 10-20 minutes.

[0076] It is worth noting that the heating temperature of the flat sheet here is determined by the actual material of the flat sheet; for example, the flat sheet is heated to 50°C at a heating rate of 4°C / min.

[0077] Alternatively, the flat sheet can be heated to 70°C at a heating rate of 5°C / min;

[0078] More specifically, the heating rate can be 3℃ / min, 4℃ / min, or 5℃ / min, without limitation. In the actual heating process, the appropriate heating rate should be selected according to different materials.

[0079] Specifically, during the heating process, the flat sheet is heated at a uniform rate to stabilize the heating process and reduce the possibility of thermal stress generated inside the material due to rapid heating, which could lead to cracks or deformation. In addition, the flat sheet is kept at 65°C for 10-20 minutes. In this embodiment, it is preferable to keep the flat sheet at 65°C for 15 minutes. In the actual heat preservation process, different heat preservation times can be switched according to the material requirements of different flat sheets.

[0080] In some embodiments, the process of evacuating the preforming fixture through a vacuum nozzle on the preforming fixture and maintaining the preforming fixture at a set temperature until the flat sheet is initially shaped includes:

[0081] Vacuum the preform tooling and keep it at a temperature above 50°C for more than 20 minutes when the air pressure inside the preform tooling is -15kPa or below.

[0082] The preform tooling is evacuated again. When the air pressure inside the preform tooling is below -80 kPa, it is kept at a temperature above 60°C for more than 5 minutes.

[0083] In some embodiments,

[0084] The pre-forming fixture is evacuated at a relatively slow rate. When the internal pressure of the pre-forming fixture is -15 kPa or below, it is maintained at a temperature above 50°C for at least 20 minutes. Specifically, the relatively slow rate is selected as 0.01 kPa / s, i.e., the pre-forming fixture is evacuated at a rate of 0.01 kPa / s. In addition, other evacuation rates can be selected, such as 0.03 kPa / s, 0.05 kPa / s, 0.07 kPa / s, or 0.09 kPa / s. In the actual evacuation process, different evacuation rates are selected according to different requirements, primarily to meet the initial vacuum requirements. When the internal pressure of the pre-forming fixture is -15 kPa or below, a pressure of -17 kPa is preferred here. Other rates include -15 kPa, -20 kPa, or -25 kPa. In the actual evacuation process, the pressure inside the pre-forming fixture is adjusted to the appropriate required pressure according to different needs. More specifically, the temperature is maintained at 50°C or above for at least 20 minutes, preferably at 65°C for 20-40 minutes; furthermore, it is maintained at 65°C for 30 minutes; in addition, a temperature range of 50°C or 60°C can also be selected; the holding time at this temperature can be selected as 20 minutes or 40 minutes, etc.

[0085] In some embodiments,

[0086] The pre-forming fixture is evacuated at a relatively rapid rate. When the internal pressure of the pre-forming fixture is below -80 kPa, it is maintained at a temperature above 60°C for at least 5 minutes. Specifically, a relatively rapid rate of 10 kPa / s is selected here, meaning the pre-forming fixture is evacuated at a rate of 10 kPa / s. In addition, evacuation rates of 15 kPa / s, 20 kPa / s, or 25 kPa / s can also be used. In the actual evacuation process, different evacuation rates are selected according to different requirements, primarily to meet the vacuum requirements of further processing. When the internal pressure of the pre-forming fixture is -80 kPa or below, a pressure of -85 kPa is preferred here. Other options include -80 kPa, -90 kPa, or -95 kPa. In the actual evacuation process, the pressure inside the pre-forming fixture is adjusted to the appropriate required pressure according to different needs. More specifically, the temperature is maintained at 60°C or above for at least 5 minutes, preferably at 65°C for 5-10 minutes; furthermore, it is selected to maintain at 65°C for 5 minutes; in addition, the temperature range of 50°C or 60°C can also be selected; the holding time at this temperature can be selected as 10 minutes.

[0087] In some embodiments, a pressure regulating valve is provided inside the heating equipment. After the pre-forming tooling and flat sheet are transferred into the heating equipment, the vacuum nozzle and the pressure regulating valve are connected to facilitate the vacuuming process. Specifically, the vacuum nozzle and the pressure regulating valve are connected first, and then preheating or heat preservation steps are performed inside the heating equipment. Alternatively, the pressure regulating valve can be directly installed inside the heating equipment, and then a vacuum is performed using an external vacuuming device. Or, the vacuuming device can be located inside the heating equipment, and the pressure regulating valve can be located on the vacuuming device. It is worth noting that when the vacuuming device is located inside the heating equipment, the vacuuming device is covered with heat-insulating material, which can be heat-insulating cotton or other materials, ensuring that the heating process does not affect the vacuuming device.

[0088] In some embodiments, a thermocouple monitoring platform is provided on the heating equipment. After the preformed tooling and flat sheet are transferred into the heating equipment, the thermocouple is electrically connected to the thermocouple monitoring platform through a line. The thermocouple monitoring platform can monitor the temperature of the thermocouple in real time to determine the state of the flat sheet at this time. Specifically, the outside of the line is covered with heat insulation material, which can be heat insulation cotton or other materials, with the main consideration that the heating process will not affect the line.

[0089] In some embodiments, a heating curve of the heating device is set before heating. Specifically, when a curing oven is used for heating, a heating curve of the curing oven is set before heating, and the curing oven is pre-formed according to the heating curve.

[0090] More specifically, the vacuuming process is divided into two stages. In the first stage, during the vacuuming of the preform tooling at a rate of 0.01 kPa / s, slow vacuuming prevents the material from being damaged by excessively rapid vacuuming. Slow vacuuming also allows sufficient time for air to escape from the material, reducing air trapped in the flat sheet. In this first stage, the vacuum bag film gradually adapts to the shape of the mold, reducing the occurrence of poor vacuum bag film adhesion caused by rapid vacuuming. In the second stage, after slow vacuuming, rapid vacuuming helps the mold achieve a higher vacuum level, thereby better removing air and volatiles. While ensuring material safety, rapid vacuuming can shorten the overall vacuuming process time and improve production efficiency. Specifically, in the first stage, the temperature is maintained at 65°C for 20-40 minutes, preferably 30 minutes in this embodiment. In the second stage, the temperature is maintained at 65°C for 5-10 minutes, preferably 5 minutes.

[0091] In this embodiment, the process of curing the flat sheet includes cooling the flat sheet to below 50°C, keeping the flat sheet in a vacuum state for more than 5 minutes, and curing the flat sheet.

[0092] In some embodiments, cooling the flat sheet to below 50°C can be selected as cooling the flat sheet to 30°C; in addition, it can also be selected as cooling to 40°C or 20°C, and the temperature can be adjusted according to the cooling requirements during the actual cooling process.

[0093] In some embodiments, after cooling, the flat sheet is kept in a vacuum state for more than 5 minutes. In this embodiment, it is preferred to keep the flat sheet in a vacuum state for 5 minutes, that is, to release the vacuum after a 5-minute delay, which can better pre-form the flat sheet. In addition, the flat sheet can also be kept in a vacuum state for 10 minutes, 15 minutes, etc., and adjusted according to the actual situation.

[0094] In some embodiments, the preforming equipment includes a heating device and a preforming fixture. Processing by this method can avoid the limitation of the size and structure of the flat sheet material by the preforming equipment.

[0095] The implementation principle of the preforming method for wall panels in this application embodiment is as follows: A preforming fixture is prepared, a release film 200 is laid on the preforming fixture, a flat sheet is placed on the release film 200, and then a peelable fabric is laid on the flat sheet. After the peelable fabric is laid, a vacuum bag film is placed on the preforming fixture, and the entire preforming fixture is transferred to the heating equipment. Inside the heating equipment, preheating, vacuuming for preliminary forming, heat preservation, and curing of the preform are performed, thereby completing the processing of the flat sheet. Simultaneously, this method enables automated forming of large-size and high-curvature deep U-shaped wall panels, with high process efficiency and guaranteed forming quality. It avoids equipment limitations on the size and curvature structure of the parts, reducing part forming costs. This method has relatively simple mold requirements, reducing mold design and manufacturing costs. Using ordinary vacuum bags and curing ovens, it achieves the preforming effect of a heat-insulating film without the need for a heat-insulating film or imported high-elongation vacuum bag film, reducing the occurrence of failure modes after preforming and ensuring forming quality.

[0096] While the embodiments of this application have been described in detail above, it will be apparent to those skilled in the art that various modifications and variations can be made to these embodiments. However, it should be understood that such modifications and variations fall within the scope and spirit of this application as set forth in the claims. Furthermore, the application described herein may have other embodiments and can be implemented or carried out in various ways.

Claims

1. A method for preforming a wall panel, comprising the following steps: The flat sheet is laid flat and placed on the preforming fixture, so that both ends of the flat sheet extend into the grooves at both ends of the preforming fixture. A vacuum bag film is laid on the flat sheet to cover the flat sheet; Connect the vacuum bag film to the edge of the forming fixture to seal the pre-forming fixture; The preformed tooling and the flat sheet are transferred to a heating device for heating. as well as The interior of the preforming fixture is evacuated to allow the flat sheet to adhere to the preforming fixture, thus completing the preforming process.

2. The wall panel preforming method according to claim 1 further includes: Before placing the flat sheet on the preforming fixture, a release film is laid on the preforming fixture, with both ends of the release film extending to the grooves at both ends of the preforming fixture and connecting with the edges of the preforming fixture.

3. The wall panel preforming method according to claim 1 further includes: Before laying the vacuum bag film on the flat sheet, a peelable fabric is laid on the flat sheet so that the peelable fabric covers the flat sheet.

4. The wall panel preforming method according to claim 1 further includes: After the vacuum bag film is laid on the flat sheet, the end of the vacuum bag extending into the groove is pleated.

5. The wall panel preforming method according to claim 1 further includes: After the flat sheet is laid flat and placed on the preforming fixture, multiple thermocouples are set in the area of ​​the flat sheet to be deformed to measure the temperature of the area of ​​the flat sheet to be deformed.

6. The wall panel preforming method according to claim 5, wherein, Multiple thermocouples are placed in the area of ​​the flat sheet to be deformed, including: The thermocouples are provided on both the front and back surfaces of the flat sheet, so that multiple thermocouples are placed in the area of ​​the flat sheet to be deformed. The thermocouple is fixed by pressure-sensitive adhesive tape; The temperature of the front and back surfaces of the flat sheet was measured using thermocouples.

7. The wall panel preforming method according to claim 1 further includes: Before evacuating the interior of the preforming fixture in the heating device, the flat sheet is heated; and when evacuating the interior of the preforming fixture in the heating device, the preforming fixture is evacuated through the vacuum nozzle on the preforming fixture, and the preforming fixture is kept at a set temperature until the flat sheet is initially shaped.

8. The wall panel preforming method according to claim 7, wherein, The heating of the flat sheet includes: the flat sheet being heated at a uniform rate to above 50°C, and maintained at a temperature above 50°C for more than 10 minutes.

9. The wall panel preforming method according to claim 7, wherein, The step of evacuating the preforming fixture by means of a vacuum nozzle on the preforming fixture, and maintaining the preforming fixture at a set temperature until the flat sheet material is initially shaped, includes: The preform tooling is evacuated, and when the air pressure inside the preform tooling is -15 kPa or below, it is kept at a temperature above 50°C for more than 20 minutes. The preform tooling is evacuated again, and when the air pressure inside the preform tooling is below -80 kPa, it is kept at a temperature above 60°C for more than 5 minutes.

10. The wall panel preforming method according to claim 7, wherein, The step of fitting the flat sheet material into the preforming fixture to complete the preforming includes: The flat sheet is cooled to below 50°C and kept in a vacuum for more than 5 minutes to pre-form the flat sheet.

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