Wallboard preforming method

Abstract

The invention discloses a wallboard pre-forming method, which comprises the following steps of: paving a flat plate material sheet, and placing the flat plate material sheet on a pre-forming tool, so that two ends of the flat plate material sheet respectively extend to grooves in two ends of the pre-forming tool; a vacuum bag film is laid on the flat plate material piece, and the flat plate material piece is covered with the vacuum bag film; the vacuum bag film is connected with the edge of the forming tool, and the pre-forming tool is sealed; the pre-forming tool and the flat plate material sheet are transferred to heating equipment to be heated; and the interior of the pre-forming tool is vacuumized, so that the flat plate material sheet is attached to the pre-forming tool, and pre-forming is completed. The size and the structure of the flat plate material sheet can be prevented from being limited by preforming equipment, and the production efficiency is improved.

Description

Technical Field

[0001] The invention relates to the technical field of aviation manufacturing, and in particular to a wall panel preforming method. Background Art

[0002] In the field of aviation manufacturing, composite materials have replaced most metal materials with their superb comprehensive properties. With the extensive application of composite materials, the automatic layup technology of composite parts has developed rapidly, gradually replacing the traditional manual layup method. In order to continuously improve the quality of finished parts, preforming has become a key link in the entire forming process. Preforming technology can be used to obtain L-shaped, C-shaped and Ω-shaped composite preformed products; however, it is difficult to achieve preforming technology that can ensure both the preforming quality and production efficiency for the preparation of more complex shell products.

[0003] At present, complex shapes such as shell products are mainly formed by hand laying, automatic wire laying & tape laying and hot diaphragm preforming. Among them, the hot diaphragm preforming method generally first lays a flat plate, and then uses a single-layer diaphragm or a double-layer diaphragm for preforming. Due to the limitations of hot diaphragm equipment, the depth or arch height of the part should not be too large, and the R corner of the product will inevitably be subjected to the out-of-plane normal pressure and the material's own adhesion during the preforming process, resulting in failure. The main failure forms are surface bridging, fiber in-plane buckling and out-of-plane wrinkles, which reduce production efficiency.

[0004] Therefore, it is necessary to provide a new wall panel preforming method to solve the above problems existing in the prior art. Summary of the invention

[0005] The object of the present invention is to provide a wall panel preforming method for processing the wall panel, which can avoid the size and structure of the flat sheet being limited by the preforming equipment and improve the production efficiency.

[0006] To achieve the above object, the technical solution of the present invention is as follows: A wall panel preforming method comprises the following steps: Laying the flat sheet flat and placing it on the preforming tooling, so that both ends of the flat sheet extend to the grooves at both ends of the preforming tooling respectively; 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 preform tool to seal the preform tool; Transferring the preform tooling and the flat sheet to a heating device for heating; The interior of the preforming tool is evacuated to make the flat sheet fit the preforming tool, thereby completing the preforming.

[0007] By adopting the above technical scheme, since the two ends of the flat sheet extend to the grooves at the two ends of the preforming tooling respectively, when the shape of the flat sheet changes, it can be deformed along the side wall of the groove. At least one side wall of the groove is arranged in an arc shape, which can make the flat sheet transition smoothly, so it can adapt to parts with large depth or large arch height; at the same time, the vacuum bag film covers the flat sheet, and during the vacuuming process, the vacuum bag film shrinks, providing uniform force on the flat sheet, thereby reducing the occurrence of surface bridging, fiber in-plane buckling and out-of-plane wrinkles, thereby improving the production efficiency of the wall panel; in addition, it can realize the automatic forming of large-size and large-curvature deep U wall panels, with high process efficiency and guaranteed forming quality; avoid the size and curvature structure of the workpiece being limited by the equipment, and reduce the part forming cost; at the same time, this method has relatively simple requirements on the mold, which reduces the mold design and manufacturing cost; using ordinary vacuum bags and curing furnaces, without the need for thermal diaphragm equipment, and without the use of imported high-elongation vacuum bag films, the thermal diaphragm preforming effect can be achieved, reducing the occurrence of failure forms after preforming.

[0008] Optionally, before placing the flat sheet on the preforming tool, the process further includes: An isolation film is laid on the preforming tooling, so that both ends of the isolation film extend to the grooves at both ends of the preforming tooling and are connected to the edges of the preforming tooling.

[0009] Optionally, before laying the vacuum bag film on the flat sheet, the method further includes: A peelable cloth is laid on the flat sheet so that the peelable cloth covers the flat sheet.

[0010] Optionally, after laying the vacuum bag film on the flat sheet, the method further comprises: The end of the vacuum bag extending to the groove is pleated.

[0011] Optionally, after flattening the flat sheet and placing it on the preformed tool, the process further includes: A plurality of thermocouples are arranged in the area where the flat sheet is to be deformed, and the temperature of the area where the flat sheet is to be deformed is measured.

[0012] Optionally, a plurality of thermocouples are arranged in the area to be deformed of the flat sheet, including: The thermocouples are arranged on both the front and back surfaces of the flat sheet, so that a plurality of the thermocouples are placed in the area of ​​the flat sheet to be deformed; fixing the thermocouple by pressure-sensitive tape; The temperature of the front and back surfaces of the flat sheet is measured respectively by using thermocouples.

[0013] Optionally, before vacuuming the interior of the preform tool in the heating device, the method further includes: heating the flat sheet; When the interior of the preform tool is vacuumed in the heating device, the method further comprises: The preforming tool is evacuated through a vacuum nozzle on the preforming tool, and the preforming tool is kept at a set temperature until the flat sheet is initially shaped.

[0014] Optionally, heating the flat sheet includes: The temperature of the flat sheet is raised to above 50° C. at a uniform rate and maintained at a temperature above 50° C. for more than 10 minutes.

[0015] Optionally, the preforming tooling is vacuumed by a vacuum nozzle on the preforming tooling, and the preforming tooling is kept at a set temperature until the flat sheet is initially shaped, including: The preform tooling is vacuumed, and when the air pressure in the preform tooling is -15 kPa or less, it is maintained at a temperature above 50° C. for more than 20 minutes; The preform tooling is vacuumed again, and when the air pressure in the preform tooling is below -80 kPa, it is maintained at a temperature above 60° C. for more than 5 minutes.

[0016] Optionally, the step of making the flat sheet fit the preforming tool to complete preforming includes: The flat sheet is cooled to below 50° C. and kept in a vacuum state for more than 5 minutes to preform the flat sheet. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A step diagram of a wall panel preforming method according to an embodiment of the present invention; Figure 2 It is a structural schematic diagram of a preforming tool in a wall panel preforming method according to an embodiment of the present invention; Figure 3 A schematic diagram of the positions of an isolation film and a pressure-sensitive adhesive tape in a wall panel preforming method according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the installation position of a thermocouple on a preforming tool in a wall panel preforming method according to an embodiment of the present invention.

[0018] Reference numerals: 100, frame body; 110, boss; 120, groove; 130, molding panel; 140, vacuum nozzle base; 200, isolation film; 300, pressure-sensitive tape; 410, first installation position; 420, second installation position. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Unless otherwise defined, the technical terms or scientific terms used herein should be understood by people with general skills in the field to which the present invention belongs. "Including" and similar words used in this article mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects.

[0020] In the field of aviation manufacturing, composite materials have replaced most metal materials with their superb comprehensive properties. With the extensive application of composite materials, the automatic layup technology of composite parts has developed rapidly, gradually replacing the traditional manual layup method. In order to continuously improve the quality of finished parts, preforming has become a key link in the entire forming process. Preforming technology can be used to obtain L-shaped, C-shaped and Ω-shaped composite preformed products; however, it is difficult to achieve preforming technology that can ensure both the preforming quality and production efficiency for the preparation of more complex shell products.

[0021] At present, complex shapes such as shell products are mainly formed by hand-laying, automatic wire laying & tape laying and hot diaphragm preforming. The hand-laying method has low process efficiency, high labor intensity and difficult to ensure molding quality; although the automatic wire laying method and the automatic tape laying method have high production efficiency and are conducive to automated production, the mold manufacturing is complex, the equipment cost is high, and the manufacturing of parts with large size and curvature is limited by the equipment; the hot diaphragm preforming method generally first lays a flat plate, and then uses a single-layer diaphragm or a double-layer diaphragm for preforming. Due to the limitation of the hot diaphragm equipment, the depth or arch height of the part should not be too large, and the R corner of the product will inevitably be subjected to the out-of-plane normal pressure and the material's own adhesion during the preforming process, resulting in failure forms. The main failure forms are surface bridging, fiber in-plane buckling and out-of-plane wrinkles.

[0022] Especially for the preforming of large-size deep U-shaped wall panels, due to the large depth of the parts, the use of thermal diaphragm equipment is limited. Therefore, the curing furnace vacuum process is adopted in this application to realize the process method of preforming large-size deep U-shaped wall panels, and simple tooling is designed to avoid the size and structure of the parts being limited by the equipment. There is no need to use imported high-strength vacuum bag film, and the process is adjusted to reduce the occurrence of failure forms after preforming, thereby improving the forming quality of the web area and R corner of the deep U-shaped wall panel.

[0023] In response to the above, the present application provides a wall panel preforming method, which is suitable for U-shaped wall panels, C-shaped wall panels, or other shaped wall panels, especially suitable for wall panels with large arch heights. In this embodiment, the preforming of large-size deep U-shaped wall panels is taken as an example.

[0024] The specific implementation modes of the present invention will be further described in detail below in conjunction with the accompanying drawings.

[0025] refer to Figure 1 An embodiment of the present invention provides a wall panel preforming method, wherein the method is applicable to large-sized deep U-shaped wall panels, and comprises the following steps: S100, prepare a flat tooling, lay a flat sheet on the flat tooling, so that the flat sheet is in a flat state, and place the flat sheet on a preforming tooling, so that both ends of the flat sheet extend to the grooves 120 at both ends of the preforming tooling respectively; S200, laying a vacuum bag film on the flat sheet so that the vacuum bag film covers the flat sheet; S300, connecting the edge of the vacuum bag film with the edge of the forming tooling, so that the vacuum bag film seals the pre-forming tooling, and at this time, the flat sheet is placed between the pre-forming tooling and the vacuum bag film; S400, transferring the preformed tooling and the flat sheet to a heating device, and heating them in the heating device; S500, in a heating device, the interior of the preforming tool is evacuated through a vacuum nozzle to make the flat sheet fit the preforming tool, and then the flat sheet is cured to preform the flat sheet.

[0026] In some embodiments, the function of the flat plate tooling is to facilitate flattening of the flat plate sheet, wherein the flat plate tooling is a prior art and will not be described in detail herein.

[0027] The preformed tooling includes a frame body 100; Figure 2, wherein the frame body 100 is hollow, and the top of the frame body 100 is open, that is, the frame body 100 forms a shell shape with an open top, and a boss 110 is provided at the inner bottom of the frame body 100 by an integrated molding method, and a gap is provided between the top of the boss 110 and the top of the frame body 100, so that after the flat sheet is placed in the frame body 100, the flat sheet will not protrude from the frame body 100, and the setting of the boss 110 forms two grooves 120 inside the frame body 100, and the two grooves 120 are respectively placed at the two ends of the frame body 100, and a molding panel 130 is provided on the boss 110 of the frame body 100, and the molding panel 130 is used to place the flat sheet In addition, a vacuum nozzle base 140 for vacuuming is provided on the frame body 100, and a vacuum nozzle base 140 is used to install a vacuum nozzle; in the present embodiment, the vacuum nozzle base 140 is placed at two diagonally opposite corners of the boss 110; in the above-mentioned S100, the flat sheet is placed on the pre-forming tooling, which actually refers to placing the flat sheet on the forming panel 130; in the above-mentioned S300, the edge of the vacuum bag film is connected to the edge of the forming tooling so that the vacuum bag film seals the pre-forming tooling, which actually refers to connecting the edge of the vacuum bag film to the edge of the frame body 100 so that the interior of the frame body 100 is in a sealed state.

[0028] In some embodiments, it is necessary to stick an air-conducting material in the groove 120 and in the area on the boss 110 where the molding panel 130 is not provided. The air-conducting material can be selected to be breathable felt, polyester fiber mesh, or non-woven fabric, etc., as long as it can achieve air permeability and air conduction.

[0029] In some embodiments, the process of initially shaping the flat sheet and completing the preforming process mainly relies on the limitation of the groove 120 and the curved side wall of the groove 120, thereby avoiding the size and structure of the flat sheet being limited by the preforming tooling, thereby improving production efficiency.

[0030] In this embodiment, refer to Figure 1 and Figure 3 Before placing the flat sheet on the preforming tooling, an isolation film 200 is laid on the preforming tooling, and both ends of the isolation film 200 extend to the grooves 120 at both ends of the preforming tooling.

[0031] In some embodiments, the isolation film is fixed on the preformed tool to imitate the effect of the double diaphragm configuration, and the isolation film is tightened so as to support the weight of the flat sheet. In some more specific embodiments, the isolation film is preferably a transparent isolation film.

[0032] Specifically, the isolation film 200 is mainly used to isolate the flat sheet and the molding panel 130 to facilitate the subsequent demolding process. The isolation film 200 at least covers the molding panel 130. During the installation of the isolation film 200, the isolation film 200 is connected to the edge of the pre-molded tooling through the pressure-sensitive tape 300, so that the isolation film 200 is laid flat on the molding panel 130; in some embodiments, before pasting the pressure-sensitive tape 300, the edge of the pre-molded tooling and the surface of the isolation film 200 need to be cleaned to reduce the pressure-sensitive tape 300 and the isolation film 200 or the pre-molded tooling. Possibility of edge detachment; in some embodiments, the isolation film 200 covers part of the groove 120, and the isolation film 200 helps to maintain the smoothness of the surface of the composite material and prevent the defects of the mold surface from being transferred to the composite material. The isolation film 200 can be made of 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.

[0033] In some embodiments, in addition to being connected via the pressure-sensitive tape 300, the isolation film 200 and the pre-forming tooling can also be fixed by a clamp or an adhesive, without limitation herein, so that the isolation film 200 can be connected to the pre-forming tooling to prevent the isolation film 200 from collapsing and causing wrinkles during the heating stage. At the same time, compared with the prior art, the present method does not require hot diaphragm equipment or imported high-strength vacuum bag film to achieve the hot diaphragm pre-forming effect. At the same time, the economic benefits can be improved by replacing equipment.

[0034] In some embodiments, a positioning piece is further provided on the pre-forming tooling. Specifically, the positioning piece is arranged on the boss 110 of the frame body 100. At the same time, a plurality of positioning pieces are arranged, and the plurality of positioning pieces 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 piece, thereby limiting the position of the flat sheet on the boss 110, thereby reducing the possibility of the position of the flat sheet being offset.

[0035] In some embodiments, the preformed tooling is made entirely of aluminum alloy. Aluminum alloy has a low density, which makes the preformed tooling light overall and easy to carry and operate. At the same time, aluminum alloy has high strength, which can ensure that the tooling maintains the stability of shape and size during operation. In addition, aluminum alloy has good corrosion resistance, is suitable for use in a variety of environments, and extends the service life of the tooling.

[0036] In some embodiments, the forming panel 130 uses a material with a low thermal conductivity. Specifically, the material with a 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., without limitation herein, and the main purpose is to reduce the heat transfer. The material with a low thermal conductivity is selected to reduce the heat transferred 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 of the flat sheet due to excessive heating.

[0037] In this embodiment, before laying the vacuum bag film on the flat sheet, it is also necessary to lay a peelable cloth on the flat sheet, wherein the peelable cloth at least covers the flat sheet, and the peelable cloth is mainly used to provide an easily peelable surface to protect the cured wall panel surface from contamination or damage, and also facilitate subsequent processing; in addition, during the curing process, the peelable cloth needs to have a certain strength to withstand a certain pressure and operation, and at the same time, it is not easy to break when peeled off.

[0038] In some embodiments, the peelable cloth can be made of polyester non-woven fabric, glass fiber reinforced polyester or nylon cloth, Teflon (PTFE) coated glass fiber cloth, polytetrafluoroethylene (PTFE) film, etc. In actual use, different films can be selected according to different needs. It can be fixed on the flat sheet by a small amount of adhesive, or when a vacuum is applied, the peelable cloth is pressed against the surface of the mold or composite material without the need for additional adhesive.

[0039] In this embodiment, after the vacuum bag film is laid on the flat sheet, the end of the vacuum bag extending to the groove 120 needs to be pleated.

[0040] In some embodiments, the more pleats there are, the better the effect of the subsequent vacuuming process. Therefore, in this embodiment, the number of pleats is not limited, and pleats are made according to actual needs during use to prevent the vacuum bag from becoming airtight when it is tightened. In addition, the pleating process should ensure that the pleats are uniform and neat, without damage or excessive deformation. At the same time, after pleating is completed, the edge of the vacuum bag film needs to be connected to the edge of the frame body 100 to ensure sealing.

[0041] In some embodiments, the vacuum bag film is pleated by manual pleating. Specifically, the ends of the vacuum bag film can be manually folded at a certain interval and width to form fan-shaped pleats, or multiple parallel pleats; or the edges of the vacuum bag film can be manually pinched to form irregular pleats.

[0042] 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 special pleating device can be used to make uniform folds on the vacuum bag film.

[0043] In some embodiments, the vacuum bag film is pleated by a heat pleating method. Specifically, a heat pressing tool can be used to heat the vacuum bag film, fold it after it softens, and fix the pleated shape after cooling; or a hot air gun can be used to locally heat the vacuum bag film, soften it, and then fold it.

[0044] More specifically, the purpose of pleating is to ensure that the vacuum bag film can fully fit 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 fit evenly on 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; reasonably design the position and number of pleats according to the shape of different workpieces and deformation during the curing process.

[0045] After the flat sheet is laid flat and placed on the preformed tooling, it also includes: A plurality of thermocouples are arranged in the area where the flat sheet is to be deformed, and the temperature of the area where the flat sheet is to be deformed is measured.

[0046] Specifically, the thermocouple measures the temperature of the area to be deformed on the flat sheet, that is, the R corner of the flat sheet, because the R corner is the area where the temperature gradient may occur on the component. Since heat may be conducted unevenly in these areas, setting up thermocouples can help monitor and ensure uniform temperature distribution throughout the component. At the same time, the shape of the R corner area may cause the heat conduction rate to be different from that of the flat area. Thermocouples can provide specific data on these differences so that the heating process can be adjusted.

[0047] In some embodiments, the vacuuming rate in the subsequent processing is adjusted in real time according to the temperature feedback of the thermocouple, that is, the process is adjusted in real time so that the area of ​​the flat sheet to be deformed is always under stable force, thereby reducing the occurrence of failure forms after preforming.

[0048] In some embodiments, a plurality of thermocouples are arranged in the area to be deformed of the flat sheet, specifically, thermocouples are arranged on both the front and back surfaces of the flat sheet, referring to Figure 4 , wherein the first installation position 410 is the installation position of the thermocouple on the front side of the flat sheet, and the second installation position 420 is the installation position of the thermocouple on the back side of the flat sheet.

[0049] In some embodiments, multiple thermocouples are respectively installed at a first installation position 410 and a 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 a pressure-sensitive tape 300 so that the position of the thermocouples does not move; at the same time, the thermocouples are used to measure the temperature of the front and back surfaces of the flat sheet.

[0050] Specifically, in this embodiment, four thermocouples are selected, of which two thermocouples are arranged on the front side of the flat sheet, and the remaining two thermocouples are arranged on the back side of the flat sheet. In addition, the two thermocouples located on the same side are arranged at an oblique angle, that is, the four thermocouples can together form a rectangle. Among the four thermocouples, the two thermocouples arranged at opposite angles are located on the same side of the flat sheet.

[0051] In some embodiments, the thermocouple is fixed by a clamp, or fixed by bolts, or fixed by welding; there is no limitation here, as long as the thermocouple can detect the temperature of the area to be deformed of the flat sheet. At the same time, according to the flat sheet of different materials, it is necessary to consider factors such as the type of thermocouple, the measurement environment, the temperature range, the geometry of the fixed position, and whether long-term monitoring is required; to ensure the stability and measurement accuracy of the thermocouple.

[0052] In this embodiment, before the interior of the preform tooling is vacuumed in the heating equipment, the flat sheet needs to be heated to preheat the flat sheet; when the interior of the preform tooling is vacuumed in the heating equipment, the preform tooling needs to be vacuumed through the vacuum nozzle on the preform tooling, and the preform tooling needs to be kept at the set temperature until the flat sheet is initially formed.

[0053] Specifically, preheating helps the temperature inside and outside the material to be consistent, thereby reducing the internal stress caused by the temperature gradient. Especially for some metal materials, preheating can improve their plasticity, making the material easier to deform without breaking during subsequent forming or processing. At the same time, preheating allows the flat sheet to reach a specific temperature before processing to ensure the quality of the flat sheet after processing.

[0054] In some embodiments, the heating device is a curing oven.

[0055] In some embodiments, the use of a curing oven avoids the investment and operating costs of expensive thermal diaphragm equipment; while thermal diaphragm equipment usually requires complex molds and higher equipment costs, the curing oven is relatively simple and economical; the curing oven can adapt to the preforming of parts with larger sizes and deeper curvatures, while the thermal diaphragm equipment has certain restrictions on the depth or arch height of the parts due to technical limitations, and is not suitable for the preforming of parts such as large-sized deep U-shaped wall panels; in addition, the curing oven vacuum process can reduce the failure forms after preforming, such as surface bridging, fiber in-plane buckling and out-of-plane wrinkling, etc., which are more common in the thermal diaphragm preforming process; the process using the curing oven has simpler requirements for the mold, reducing the mold design and manufacturing costs, while thermal diaphragm equipment usually requires more complex mold design; the curing oven process can realize automated preforming and improve production efficiency, while the thermal diaphragm process has more manual operations and lower efficiency; the curing oven process does not require the use of imported high-elongation vacuum bag film, and can use ordinary vacuum bags, which reduces material costs and also reduces preforming failures caused by material problems.

[0056] In some more specific embodiments, if the depth of the part exceeds the extension capacity of the device diaphragm or the effective range of the heating system, the thermal diaphragm device may not be applicable. For example, if the depth of the part exceeds tens of millimeters to hundreds of millimeters, such as a part depth of 500mm; it may exceed the processing capacity of some thermal diaphragm equipment. For parts with a higher arch structure, the thermal diaphragm equipment may not provide enough pressure to maintain close contact between the diaphragm and the mold and the material, thereby affecting the preforming effect; for large-sized parts, such as parts with a width or length exceeding the size of the thermal diaphragm equipment workbench, it may also be unsuitable to use the thermal diaphragm equipment. In this solution, the preforming tool cooperates with the curing furnace and vacuums through the vacuum nozzle, which can provide enough pressure to maintain close contact between the diaphragm and the mold and the material. At the same time, the preforming tool will not limit the size of the flat sheet, and can process parts with a depth of tens of millimeters to hundreds of millimeters.

[0057] In some embodiments, the heating device may also be an autoclave or an oven, etc., mainly to meet the heating requirements of the flat sheet.

[0058] In some embodiments, the preformed tooling and the flat sheet are transferred to a heating device, and the heating device is controlled to increase or keep the temperature so that the temperature inside the heating device reaches a desired temperature to heat or keep the flat sheet warm.

[0059] In some embodiments, the temperature of the flat sheet is raised to above 50° C. at a uniform rate and maintained at a temperature above 50° C. for more than 10 minutes.

[0060] 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 maintaining the flat sheet at 65° C. for 10-20 min.

[0061] It is worth noting that the heating temperature of the flat sheet is determined according to 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; Or the flat sheet is heated to 70°C at a heating rate of 5°C / min; More specifically, the heating rate may be 3°C / min, 4°C / min, or 5°C / min, which is not limited here. In the actual heating process, a suitable heating rate is selected according to different materials.

[0062] Specifically, during the heating process, the temperature of the flat sheet is raised at a uniform rate to stabilize the heating process of the flat sheet, thereby reducing the possibility of thermal stress inside the material caused by rapid heating, thereby causing cracks or deformation. In addition, the flat sheet is maintained at a temperature of 65°C for 10-20 minutes. In this embodiment, it is preferred to maintain the temperature of the flat sheet at 65°C for 15 minutes. In the actual insulation process, different insulation times can be switched according to the material requirements of different flat sheets.

[0063] In some embodiments, the process of evacuating the preforming tooling through a vacuum nozzle on the preforming tooling and maintaining the preforming tooling at a set temperature until the flat sheet is initially formed comprises: The preform tooling is vacuumed, and when the air pressure in the preform tooling is -15kPa or below, it is maintained at a temperature above 50°C for more than 20 minutes; The preform tooling is vacuumed again, and when the air pressure in the preform tooling is below -80 kPa, it is maintained at a temperature above 60° C. for more than 5 minutes.

[0064] In some embodiments, The preform tooling is vacuumed at a relatively slow rate, and when the air pressure in the preform tooling is -15kPa or less, it is maintained at a temperature above 50°C for more than 20 minutes. Specifically, the relatively slow rate here is selected as 0.01kPa / s, that is, the preform tooling is vacuumed at a rate of 0.01kPa / s; in addition, the vacuuming rate that can be selected can be 0.03kPa / s, 0.05kPa / s, 0.07kPa / s or 0.09kPa / s, etc. In the actual vacuuming process, different vacuuming rates are selected according to different needs, mainly to meet the initial vacuum requirements. Among them, when the air pressure in the preform tooling is -15kPa or less, it is preferably -17kPa in the preform tooling here. In addition, it can also be -15kPa, -20kPa or -25kPa, etc. In the actual vacuuming process, according to different needs, the air pressure in the preform tooling is adjusted to the appropriate required air pressure. More specifically, the temperature is maintained at above 50°C for more than 20 minutes, preferably at 65°C for 20-40 minutes; further, the temperature is maintained at 65°C for 30 minutes; in addition, a temperature range of 50°C or 60°C can also be selected; the time maintained at this temperature can be selected to be 20 minutes or 40 minutes, etc.

[0065] In some embodiments, The preform tooling is vacuumed at a relatively fast rate, and when the air pressure in the preform tooling is below -80kPa, it is maintained at a temperature above 60°C for more than 5 minutes. Specifically, the relatively fast rate here is selected as 10kPa / s, that is, the preform tooling is vacuumed at a rate of 10kPa / s; in addition, the vacuuming rate that can be selected can be 15kPa / s, 20kPa / s, or 25kPa / s, etc. In the actual vacuuming process, different vacuuming rates are selected according to different needs, mainly to meet the vacuum requirements for further processing. Among them, when the air pressure in the preform tooling is -80kPa and below, it is preferably here that the air pressure in the preform tooling is -85kPa. In addition, it can also be -80kPa, -90kPa or -95kPa, etc. In the actual vacuuming process, according to different needs, the air pressure in the preform tooling is adjusted to the appropriate required air pressure. More specifically, the temperature is maintained at above 60°C for more than 5 minutes, preferably at 65°C for 5-10 minutes; further, the temperature is maintained at 65°C for 5 minutes; in addition, a temperature range of 50°C or 60°C can also be selected; the time of maintaining at this temperature can be selected to be 10 minutes.

[0066] In some embodiments, a pressure-changing valve is provided in the heating device. After the preformed tooling and the flat sheet are transferred to the interior of the heating device, the vacuum nozzle and the pressure-changing valve are connected to facilitate the vacuuming process; wherein, the vacuum nozzle and the pressure-changing valve are connected first, and then the preheating or insulation step is performed inside the heating device; specifically, the pressure-changing valve can be directly installed inside the heating device, and then a vacuuming device is installed outside the heating device to perform vacuuming; or the vacuuming device is arranged inside the heating device, and the pressure-changing valve is arranged on the vacuuming device. It is worth noting that when the vacuuming device is arranged inside the heating device, the vacuuming device is coated with a heat-insulating material on the outside, wherein the heat-insulating material can be selected as heat-insulating cotton, or selected as other materials, so that the heating process will not affect the vacuuming device.

[0067] In some embodiments, a thermocouple monitoring platform is provided on the heating device. After the preformed tooling and the flat sheet are transferred to the interior of the heating device, the thermocouple is electrically connected to the thermocouple monitoring platform through a line. The temperature of the thermocouple can be observed in real time through the thermocouple monitoring platform to determine the state of the flat sheet at this time. Specifically, the outside of the line is coated with a thermal insulation material, wherein the thermal insulation material can be selected as thermal insulation cotton, or other materials, so that the heating process will not affect the line.

[0068] In some embodiments, before the heating device is used for heating, a heating curve of the heating device is set. Specifically, when a curing furnace is used for heating, a heating curve of the curing furnace is set before heating, and the curing furnace is preformed according to the heating curve.

[0069] More specifically, vacuuming is carried out in two stages, wherein in the first stage, that is, during the process of vacuuming the preformed tooling at a rate of 0.01 kPa / s, slow vacuuming can prevent the material from being damaged due to excessively rapid vacuum action, and at the same time, slow vacuuming can allow sufficient time for air to escape from the material, thereby reducing air entrained in the flat sheet. In the first stage, the vacuum bag film can gradually adapt to the shape of the mold, thereby reducing the occurrence of poor vacuum bag film fitting due to rapid vacuuming; in the second stage, after slow vacuuming, rapid vacuuming can help the inside of the mold reach a higher vacuum degree, thereby better removing air and volatiles. On the premise of ensuring material safety, rapid vacuuming can shorten the time of the entire vacuuming process and improve production efficiency, wherein, in the first stage, the temperature is maintained at 65°C for 20-40 minutes, and in this embodiment, it is preferably maintained at 65°C for 30 minutes; in the second stage, the temperature is maintained at 65°C for 5-10 minutes, and it is preferably maintained at 65°C for 5 minutes.

[0070] In this embodiment, the process of solidifying the flat sheet includes cooling the flat sheet to below 50° C. and keeping the flat sheet in a vacuum state for more than 5 minutes to solidify the flat sheet.

[0071] In some embodiments, the flat sheet material is cooled to below 50°C, which can be selected by cooling the flat sheet material to 30°C; in addition, the temperature can also be cooled to 40°C or 20°C. During the actual cooling process, the temperature is adjusted according to the cooling demand.

[0072] 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 remove the vacuum after a delay of 5 minutes, so as to 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., which can be adjusted according to actual conditions.

[0073] In some embodiments, the preforming device includes a heating device and a preforming tool. Through processing by this method, it is possible to avoid the size and structure of the flat sheet being restricted by the preforming device.

[0074] The implementation principle of a wall panel preforming method in an embodiment of the present application is to prepare a preforming tool, lay an isolation film 200 on the preforming tool, place a flat sheet on the isolation film 200, and then lay a peelable cloth on the flat sheet. After the peelable cloth is laid, a vacuum bag film is set on the preforming tool, and the preforming tool is transferred as a whole to the inside of the heating equipment, and preheating, vacuuming preliminary forming, insulation, curing preforming and other steps are performed inside the heating equipment, thereby completing the processing of the flat sheet; at the same time, this method can realize the automated forming of large-size and large-curvature deep U wall panels, with high process efficiency and guaranteed forming quality; avoid the size and curvature structure of the workpiece being limited by the equipment, and reduce the part forming cost; the method has relatively simple requirements on the mold, reducing the mold design and manufacturing costs; using ordinary vacuum bags and curing furnaces, without the need for thermal diaphragms, and without the need to use imported high-elongation vacuum bag films, the thermal diaphragm preforming effect can be achieved, the occurrence of failure forms after preforming is reduced, and the forming quality is guaranteed.

[0075] Although the embodiments of the present invention are described in detail above, it is obvious 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 are within the scope and spirit of the present invention as described in the claims. Moreover, the present invention described herein may have other embodiments and may be implemented or realized in a variety of ways.

Claims

1. A wall panel preforming method, characterized in that: The following steps are involved: Lay the flat sheet flat and place it on the preforming tooling so that both ends of the flat sheet extend to the grooves at both ends of the preforming tooling respectively; 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 forming tool to seal the preform tool; Transferring the preformed tool and the flat sheet to a heating device for heating; The interior of the preforming tool is evacuated to make the flat sheet fit the preforming tool, thereby completing the preforming.

2. The wall panel preforming method according to claim 1, characterized in that: Before placing the flat sheet on the preforming tool, the method further comprises: An isolation film is laid on the preforming tooling, so that both ends of the isolation film extend to the grooves at both ends of the preforming tooling and are connected to the edges of the preforming tooling.

3. The wall panel preforming method according to claim 1, characterized in that: Before laying the vacuum bag film on the flat sheet, the method further comprises: A peelable cloth is laid on the flat sheet so that the peelable cloth covers the flat sheet.

4. The wall panel preforming method according to claim 1, characterized in that: After laying the vacuum bag film on the flat sheet, the method further comprises: The end of the vacuum bag extending to the groove is pleated.

5. The wall panel preforming method according to claim 1, characterized in that: After the flat sheet is laid flat and placed on the preformed tooling, the method further comprises: A plurality of thermocouples are arranged in the area where the flat sheet is to be deformed, and the temperature of the area where the flat sheet is to be deformed is measured.

6. The wall panel preforming method according to claim 5, characterized in that: The step of arranging a plurality of thermocouples in the area to be deformed of the flat sheet includes: The thermocouples are arranged on both the front and back surfaces of the flat sheet, so that a plurality of the thermocouples are placed in the area of ​​the flat sheet to be deformed; fixing the thermocouple by pressure-sensitive tape; The temperature of the front and back surfaces of the flat sheet is measured respectively by using thermocouples.

7. The wall panel preforming method according to claim 1, characterized in that: Before the interior of the preform tool is vacuumed in the heating device, the method further comprises: heating the flat sheet; When the interior of the preform tool is vacuumed in the heating device, the method further comprises: The preforming tool is evacuated through a vacuum nozzle on the preforming tool, and the preforming tool is kept at a set temperature until the flat sheet is initially shaped.

8. The wall panel preforming method according to claim 7, characterized in that: The step of heating the flat sheet comprises: The temperature of the flat sheet is raised to above 50° C. at a uniform rate and maintained at a temperature above 50° C. for more than 10 minutes.

9. The wall panel preforming method according to claim 7, characterized in that: The preforming tooling is evacuated by a vacuum nozzle on the preforming tooling, and the preforming tooling is kept at a set temperature until the flat sheet is initially formed, including: The preforming tool is vacuumed, and when the air pressure in the preforming tool is -15 kPa or less, it is maintained at a temperature above 50° C. for more than 20 minutes; The preform tooling is vacuumed again, and when the air pressure in the preform tooling is below -80 kPa, it is maintained at a temperature above 60° C. for more than 5 minutes.

10. The wall panel preforming method according to claim 7, characterized in that: The step of making the flat sheet fit the preforming tool to complete the preforming includes: The flat sheet is cooled to below 50° C. and kept in a vacuum state for more than 5 minutes to preform the flat sheet.

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