Method and apparatus for forming composite parts from multi-ply prepreg composite charges

Abstract

To provide methods for producing composite parts capable of simplifying equipment and reducing the production time without the need for degassing.SOLUTION: The method comprises: placing a multi-ply prepreg composite charge (190) with a first shape in a chamber (100); reducing the pressure inside the chamber (100) to less than the atmospheric pressure; while keeping the pressure, expanding a bladder (140) by increasing the pressure inside the bladder (140) to the atmospheric pressure, so that the composite charge (190) is compressed between the bladder (140) and a forming tool (130) that is located inside the chamber (100), and is formed by the forming tool (130) into a second shape different from the first shape; and curing the composite charge.SELECTED DRAWING: Figure 2

Description

[Background technology]

[0001]

[0001] Composite materials have become increasingly popular for the manufacture of aircraft parts and other lightweight structures. Composites have excellent strength and stiffness properties and are lightweight compared to, for example, metals. However, composite structures are still very expensive to manufacture compared to, for example, metallic structures. Manufacturing costs are particularly important for large composite structures and composite structures with complex geometries. A primary factor contributing to these high manufacturing costs is equipment complexity and processing time. For example, processing of composite materials often involves degassing, which is the extraction of moisture, volatiles, and / or gases trapped within these materials. Degassing typically increases manufacturing cycle times and requires the use of specialized equipment, such as autoclaves. Summary of the Invention

[0002]

[0002] Accordingly, devices and methods aimed at addressing at least the above-mentioned concerns would find utility.

[0003]

[0003] Below is a non-exhaustive list of examples of the subject matter disclosed in this specification.

[0004] Disclosed herein is a method for forming a composite part from a multi-ply prepreg charge. The method includes reducing a pressure inside a bladder positioned within a chamber at atmospheric pressure to less than atmospheric pressure. The method also includes placing a multi-ply prepreg composite charge having a first shape into the chamber and reducing the pressure inside the chamber to less than atmospheric pressure. The method also includes expanding the bladder within the chamber by increasing the pressure inside the bladder to atmospheric pressure while maintaining the pressure inside the chamber at less than atmospheric pressure, whereby the multi-ply prepreg composite charge is compressed between the bladder and a forming tool positioned inside the chamber, and the multi-ply prepreg composite charge is formed by the forming tool into a second shape different from the first shape. The method further includes curing the multi-ply prepreg composite charge having the second shape.

[0005] The above-described sequence of operations allows for degassing of the multi-ply prepreg composite charge prior to its formation. Specifically, degassing is performed while at least a portion of the multi-ply prepreg composite charge is exposed. At this stage, the multi-ply prepreg composite charge has not yet been compressed between the bladder and the forming tool. Once the multi-ply prepreg composite charge is compressed between the bladder and the forming tool, degassing becomes less efficient because the gas path is blocked by the bladder and the forming tool. Note that degassing continues while the multi-ply prepreg composite charge is compressed between the bladder and the forming tool, but is less efficient at that point. More efficient degassing begins and continues (e.g., for a period of time) before the multi-ply prepreg composite charge is compressed between the bladder and the forming tool. Furthermore, this degassing is performed without the need for additional equipment. Both the bladder and the chamber are equipped with independent vacuum lines. This allows the pressure inside the bladder and the pressure inside the chamber to be reduced independently.

[0006]

[0006] Reference is now made to the accompanying drawings, which are not necessarily drawn to scale and in which like reference characters indicate the same or similar parts throughout the several views. In the drawings: [Brief explanation of the drawings]

[0007] [Figure 1A] 1A and 1B collectively illustrate a block diagram of a method according to one or more embodiments of the presently disclosed subject matter for forming a composite part from a multi-ply prepreg composite charge. [Figure 1B] 1A and 1B collectively illustrate a block diagram of a method according to one or more embodiments of the presently disclosed subject matter for forming a composite part from a multi-ply prepreg composite charge. [Figure 2]

[0008] 1C is a schematic cross-sectional view of a bladder positioned inside a chamber, illustrating a step of reducing the pressure inside the bladder according to the method of FIGS. 1A and 1B, in accordance with one or more embodiments of the subject matter disclosed herein. [Figure 3A]

[0009] 1C is a schematic cross-sectional view of a chamber illustrating a step of reducing the pressure inside the chamber according to the method of FIGS. 1A and 1B, in accordance with one or more embodiments of the subject matter disclosed herein. FIG. [Figure 3B]

[0010] 3B is a schematic enlarged cross-sectional view of the chamber of FIG. 3A showing various components of the chamber in accordance with one or more embodiments of the subject matter disclosed herein. [Figure 3C]

[0011] 1C is a schematic cross-sectional view of a chamber illustrating a step of reducing the pressure inside the chamber according to the method of FIGS. 1A and 1B, in accordance with one or more embodiments of the subject matter disclosed herein. FIG. [Figure 3D]

[0012] 3D is a schematic enlarged cross-sectional view of the chamber of FIG. 3C showing various components of the chamber in accordance with one or more embodiments of the subject matter disclosed herein. [Figure 3E]

[0013] 1C is a schematic cross-sectional view of a chamber illustrating a step of reducing the pressure inside the chamber according to the method of FIGS. 1A and 1B, in accordance with one or more embodiments of the subject matter disclosed herein. FIG. [Figure 3F]

[0014] 3E showing various components of the chamber in accordance with one or more embodiments of the presently disclosed subject matter. [Figure 4A]

[0015] 4A and 4B are two schematic cross-sectional views of a chamber illustrating the step of inflating a bladder within the chamber according to the method of FIGS. 1A and 1B, in accordance with one or more embodiments of the subject matter disclosed herein. [Figure 4B]4A and 4B are two schematic cross-sectional views of a chamber illustrating the step of inflating a bladder within the chamber according to the method of FIGS. 1A and 1B, in accordance with one or more embodiments of the subject matter disclosed herein. [Figure 4C]

[0016] 4C is a schematic enlarged cross-sectional view of the chamber of FIG. 4B showing various heater embodiments according to one or more embodiments of the subject matter disclosed herein. [Figure 4D]

[0017] 4D and 4E are two schematic cross-sectional views of a chamber illustrating the step of inflating a bladder within the chamber according to the method of FIGS. 1A and 1B, in accordance with one or more embodiments of the subject matter disclosed herein. [Figure 4E] 4D and 4E are two schematic cross-sectional views of a chamber illustrating the step of inflating a bladder within the chamber according to the method of FIGS. 1A and 1B, in accordance with one or more embodiments of the subject matter disclosed herein. [Figure 4F]

[0018] 1C is a schematic cross-sectional view of a chamber illustrating steps of curing a multi-ply prepreg composite charge according to the method of FIGS. 1A and 1B, in accordance with one or more embodiments of the subject matter disclosed herein. FIG. [Figure 5]

[0019] FIG. 1 is a block diagram of an apparatus for forming a composite part from a multi-ply prepreg composite charge according to one or more embodiments of the subject matter disclosed herein. [Figure 6]

[0020] FIG. 1 is a block diagram of an aircraft manufacturing and maintenance methodology. [Figure 7]

[0021] 1 is a schematic diagram of an aircraft. DETAILED DESCRIPTION OF THE INVENTION

[0008]

[0022] In FIG. 5 above, where solid lines are present connecting various elements and / or components, these solid lines may represent mechanical, electrical, fluid, optical, electromagnetic, and other couplings and / or combinations thereof. As used herein, "coupled" means directly and indirectly coupled. For example, component A may be directly coupled to component B, or may be indirectly coupled, for example, via another component C. It will be understood that not all relationships between the various disclosed elements are necessarily represented. Thus, couplings other than those depicted in the block diagrams may exist. Where dashed lines are present connecting blocks indicating various elements and / or components, these dashed lines represent couplings similar in function and purpose to those represented by solid lines. However, couplings represented by dashed lines may either be provided in preference or relate to alternative examples of the subject matter disclosed herein. Similarly, where elements and / or components represented by dashed lines are present, they represent alternative examples of the subject matter disclosed herein. One or more elements shown with solid and / or dashed lines may be omitted from particular examples without departing from the scope of the subject matter disclosed herein. Environmental elements, if present, are represented by dotted lines. Hypothetical (fictitious) elements may also be shown for clarity. Those skilled in the art will understand that some of the features shown in FIG. 5 may be combined in various ways without necessarily including other features described in FIG. 5 , other figures, and / or the accompanying disclosure (even though one or more such combinations are not explicitly set forth herein). Similarly, additional features, not limited to the examples presented, may be combined with some or all of the features shown and described herein.

[0009]

[0023] In the above-described FIGS. 1A, 1B, and 6, blocks may represent operations and / or portions thereof, and lines connecting various blocks do not imply any particular order or dependency of the operations or portions thereof. Blocks shown with dashed lines represent alternative operations and / or portions thereof. When dashed lines connect various blocks, the dashed lines represent alternative dependencies of operations or portions thereof. It should be understood that not all dependencies between various disclosed operations are necessarily represented. FIGS. 1A, 1B, and 6, and the accompanying disclosure, describing operations of the methods set forth herein, should not necessarily be construed as dictating the order in which operations are performed. Rather, while one exemplary order is shown, it should be understood that the sequence of operations can be modified where appropriate. Thus, certain operations may be performed in a different order or simultaneously. Furthermore, those skilled in the art will recognize that not all described operations need be performed.

[0010]

[0024] In the following description, numerous specific details are set forth to provide a thorough understanding of the disclosed concepts; however, these concepts may be practiced without some or all of the specific details. In other instances, details of well-known devices and / or processes are omitted to avoid unnecessarily obscuring the description. While some concepts will be described in conjunction with specific examples, it will be understood that these examples are not intended to be limiting.

[0011]

[0025] Unless otherwise indicated, the terms "first," "second," etc. are used herein merely as designators and are not intended to impose any sequential, positional, or hierarchical requirements on the items they refer to. Furthermore, a reference to, e.g., a "second" item does not require or preclude the presence of, e.g., a "first" or lower numbered item and / or, e.g., a "third" or higher numbered item.

[0012]

[0026] A reference herein to "one example" means that one or more features, structures, or characteristics described in connection with that example are included in at least one embodiment. Multiple appearances of the phrase "one or more examples" herein may or may not refer to the same example.

[0013]

[0027] As used herein, a system, device, structure, article, element, component, or hardware that is "configured to" perform a particular function is not, in fact, capable of performing that particular function without any modification, but rather may perform that particular function after further modification. In other words, a system, device, structure, article, element, component, or hardware that is "configured to" perform a particular function is specifically selected, created, implemented, utilized, programmed, and / or designed for the purpose of performing that particular function. As used herein, the phrase "configured to" refers to an existing characteristic of a system, device, structure, article, element, component, or hardware that enables the system, device, structure, article, element, component, or hardware to perform a particular function without further modification. In this disclosure, a system, device, structure, article, element, component, or hardware that is described as "configured to" perform a particular function may additionally or alternatively be described as "adapted to" and / or "operative to" perform that function.

[0014]

[0028] Illustrative, non-exhaustive examples of the subject matter according to this disclosure are provided below.

[0015]

[0029] 1A and 1B, and in particular, for example, to FIGS. 2-4D, for illustrative purposes only and not in a limiting manner, the remainder of this paragraph will describe in detail Example 1 of the presently disclosed subject matter. According to Example 1, a method 500 of forming a composite part 195 from a multi-ply prepreg composite charge 190 includes reducing a pressure inside a bladder 140 positioned within a chamber 100 at atmospheric pressure to below atmospheric pressure (block 510). Method 500 also includes placing the multi-ply prepreg composite charge 190 having a first shape within the chamber 100 (block 520). Method 500 further includes reducing the pressure inside the chamber 100 to below atmospheric pressure (block 530). The method 500 further includes expanding the bladder 140 within the chamber 100 (block 540) by increasing the pressure within the bladder 140 to atmospheric pressure while maintaining the pressure within the chamber 100 below atmospheric pressure, whereby the multi-ply prepreg composite charge 190 is compressed between the bladder 140 and a forming tool 130 positioned inside the chamber 100, and the multi-ply prepreg composite charge 190 is formed by the forming tool 130 into a second shape different from the first shape. The method 500 further includes curing the multi-ply prepreg composite charge 190 having the second shape (block 550).

[0016]

[0030] The above-described sequence of operations allows the multi-ply prepreg composite charge 190 to be degassed before it is formed. Specifically, degassing is performed while at least a portion of the multi-ply prepreg composite charge 190 (e.g., the component facing the forming tool 130) is exposed. At this stage, the multi-ply prepreg composite charge 190 is not yet compressed between the bladder 140 and the forming tool 130, and there is no restriction on gas flow from the multi-ply prepreg composite charge 190. If the multi-ply prepreg composite charge 190 is compressed between the bladder 140 and the forming tool 130, the degassing becomes less efficient because the gas path is blocked by the bladder 140 and the forming tool 130. It should be noted that degassing continues while the multi-ply prepreg composite charge 190 is compressed between the bladder 140 and the forming tool 130, but degassing at this stage is less efficient due to the gas path restriction described above. However, degassing begins and continues before the multi-ply prepreg composite charge 190 is compressed between the bladder 140 and the forming tool 130. At this stage, degassing is more efficient because there is no gas path restriction described above. Furthermore, this degassing is performed without the need for additional equipment. In some embodiments, both the bladder 140 and the chamber 100 are equipped with independent vacuum lines, thereby allowing the pressure inside the bladder 140 and the chamber 100 to be reduced independently.

[0017]

[0031] Initially, chamber 100 is at atmospheric pressure. For example, chamber 100 is open and ready to receive multi-ply prepreg composite charge 190. Bladder 140 is disposed inside chamber 100 and is, at least initially, exposed to the atmosphere. When the pressure inside bladder 140 is reduced below atmospheric pressure, the atmospheric pressure within chamber 100 and outside bladder 140 compresses bladder 140, which may also be referred to as flattening bladder 140. In some embodiments, bladder 140 is formed from a flexible material, which allows bladder 140 to change shape and flatten based on the pressure difference between the inside and outside of bladder 140.

[0018]

[0032] Once the bladder 140 is flattened, a multi-ply prepreg composite charge 190 is placed into the chamber 100. At this stage, the multi-ply prepreg composite charge 190 has a first shape, e.g., a substantially flat shape. In some embodiments, the multi-ply prepreg composite charge 190 is placed on top of the bladder 140. This process stage is shown in FIG. 2. The chamber 100 is open at this stage, providing access to the interior of the chamber 100, e.g., for placing the multi-ply prepreg composite charge 190.

[0019]

[0033] The method 500 then proceeds to reduce the pressure inside the chamber 100 to below atmospheric pressure. The chamber 100 is sealed at this stage, as shown, for example, in FIG. 3A. The pressure inside the chamber 100 is reduced, for example, by connecting the interior of the chamber 100 to a vacuum source. Note that the bladder 140 is at below atmospheric pressure at this stage. In some embodiments, the pressure inside the bladder 140 and the pressure inside the chamber 100 are the same at this stage, and both are fluidly coupled to the same vacuum source. In other embodiments, the pressure inside the bladder 140 is less than the pressure inside the chamber 100, ensuring that the bladder remains flat.

[0020]

[0034] At this stage, the multi-ply prepreg composite charge 190 is exposed to the environment inside the chamber 100. The chamber 100 is at subatmospheric pressure. At the same time, the multi-ply prepreg composite charge 190 is at least partially exposed (e.g., not in contact with any other components other than the bladder 140). Furthermore, the bladder 140 has not yet compressed the multi-ply prepreg composite charge 190. A combination of factors allows for efficient degassing of the multi-ply prepreg composite charge 190, which may be referred to as initial degassing or pre-compression degassing. This initial degassing is performed for a period of time, which depends on various factors, such as the thickness of the multi-ply prepreg composite charge 190, the material properties of the multi-ply prepreg composite charge 190 (e.g., porosity, density, elasticity), and the level of degassing required. In some embodiments, the duration of this initial degassing is between 1 minute and 1 hour, or more specifically, between 5 minutes and 30 minutes.

[0021]

[0035] Method 500 proceeds with inflation of bladder 140 within chamber 100. This step is shown diagrammatically in FIGS. 4A-4E. Inflation of bladder 140 is achieved by increasing the pressure inside bladder 140 to atmospheric pressure, for example, when bladder 140 is disconnected from a vacuum source and fluidly coupled to the atmosphere. For example, bladder 140 includes a line extending from chamber 100 and connected to valve 186, or more specifically, a three-way valve. One port of this three-way valve is open to the atmosphere. Furthermore, this bladder inflation operation is performed while the pressure inside chamber 100 is maintained below atmospheric pressure. The pressure inside bladder 140 being greater than the pressure inside chamber 100 (and outside bladder 140) causes bladder 140 to inflate.

[0022]

[0036] During this bladder expansion operation, the multi-ply prepreg composite charge 190 is compressed between the bladder 140 and the forming tool 130, as shown schematically in FIGS. 4A-4E , for example. More specifically, the multi-ply prepreg composite charge 190 is formed by the forming tool 130 into a second shape that is different from the first shape. In some embodiments, the forming tool 130 defines the second shape of the multi-ply prepreg composite charge 190. Specifically, the multi-ply prepreg composite charge 190 conforms to the forming tool 130 during the bladder expansion operation. Note that the pressure inside the chamber 100 is maintained below atmospheric pressure during this operation, thereby allowing further venting of the multi-ply prepreg composite charge 190. However, unlike the initial venting (prior to expanding the bladder 140 and compressing the multi-ply prepreg composite charge 190 within the chamber 100), this subsequent venting is less efficient. The venting path is now restricted by the bladder 140 and forming tool 130 compressing the multi-ply prepreg composite charge 190 .

[0023]

[0037] The method 500 further includes curing the multi-ply prepreg composite charge 190 having the second shape. In some embodiments, during this curing operation, the multi-ply prepreg composite charge 190 is continuously compressed between the bladder 140 and the forming tool 130. Upon completion of the curing operation, a composite part 195 is formed (from the multi-ply prepreg composite charge 190). Unlike the multi-ply prepreg composite charge 190, the composite part 195 is able to maintain its shape. Thus, the composite part 195 no longer requires additional support from the bladder 140 and the forming tool 130.

[0024]

[0038] 1A and 1B, and in particular, for example, Figures 3A-3B, for illustrative purposes only and not in a limiting manner, the remainder of this paragraph will describe in detail Example 2 of the presently disclosed subject matter. According to Example 2, which encompasses Example 1 above, during the step of reducing the pressure inside the chamber 100 to below atmospheric pressure (block 510), the multi-ply prepreg composite charge 190 is separated from the forming tool 130 by a gap 134.

[0025]

[0039] Gap 134 ensures that a portion of multi-ply prepreg composite charge 190 facing forming tool 130 remains exposed and available for venting, or more specifically, initial venting prior to compressing multi-ply prepreg composite charge 190. When forming tool 130 contacts multi-ply prepreg composite charge 190, multi-ply prepreg composite charge 190 is compressed between bladder 140 and forming tool 130, venting paths are more restricted, and venting is less efficient than initial venting.

[0026]

[0040] In some embodiments, gap 134 is at least 1 millimeter, or more specifically, at least 5 millimeters. While a large gap is not necessary because gas can travel efficiently through narrow paths, a larger gap ensures that strains in multi-ply prepreg composite charge 190 do not result in contact between forming tool 130 and multi-ply prepreg composite charge 190, thereby maintaining a continuous gas path within gap 134.

[0027]

[0041] 1A and 1B, and in particular, for example, FIGS. 2A, 3A, and 3B, the remainder of this paragraph will describe in detail Example 3 of the presently disclosed subject matter. According to Example 3, which encompasses Example 2 described above, a chamber 100 includes a chamber housing 110 and a chamber lid 120 coupled to the chamber housing 110 and pivotable relative to the chamber housing 110. Reducing the pressure inside the chamber 100 to below atmospheric pressure (block 530) and expanding the bladder 140 within the chamber 100 by increasing the pressure inside the bladder 140 to atmospheric pressure while maintaining the pressure inside the chamber 100 below atmospheric pressure (block 550) each include providing a seal between the chamber lid 120 and the chamber housing 110 (block 532). A forming tool 130 is attached to and supported by the chamber lid 120.

[0028]

[0042] Attaching the forming tool 130 to the chamber lid 120 eliminates the need for a separate support for the forming tool 130. Therefore, no additional or dedicated tooling is required to support and align the forming tool 130 within the chamber 100. Furthermore, the pivotable coupling of the chamber lid 120 to the chamber housing 110 allows the chamber 100 to be opened and accessed while maintaining the relative orientation of the chamber lid 120 and the chamber housing 110. For example, the chamber lid 120 is pivotally coupled to the chamber housing 110, as shown in FIG. 2 . Because the forming tool 130 is attached to and supported by the chamber lid 120, its alignment with the chamber housing 110 is maintained. In other words, when the chamber lid 120 is sealed to the chamber housing 110, the forming tool 130 assumes a designated position within the chamber housing 110 and relative to the multi-ply prepreg composite charge 190.

[0029]

[0043] 1A and 1B, and in particular, for example, to Figures 3A and 3B, for illustrative purposes only and not in a limiting manner, the remainder of this paragraph details Example 4 of the presently disclosed subject matter. According to Example 5, which includes any one of Examples 1-3 above, method 500 further includes heating multi-ply prepreg composite charge 190 (block 538) prior to expanding bladder 140 within chamber 100.

[0030]

[0044] Heating the multi-ply prepreg composite charge 190 prior to inflating the bladder 140 within the chamber 100 serves to degas the multi-ply prepreg composite charge 190, for example, by softening the multi-ply prepreg composite charge 190 and allowing trapped air bubbles to migrate to the surface of the multi-ply prepreg composite charge 190. As shown in Figures 3A and 3B, the forming tool 130 is not in contact with the multi-ply prepreg composite charge 190 at this stage, and the entire top surface of the multi-ply prepreg composite charge 190 is either exposed or covered by a permeable component, thereby allowing gas to escape from the multi-ply prepreg composite charge 190.

[0031]

[0045] In some embodiments, the multi-ply prepreg composite charge 190 is heated to a temperature and for a duration that does not induce or result in significant curing of the multi-ply prepreg composite charge 190. For example, the multi-ply prepreg composite charge 190 is heated to between about 50% and 80% of the curing temperature during this heating while venting operation.

[0032]

[0046] 1A and 1B, and in particular, for example, to Figures 3A and 3B, for illustrative purposes only and not in a limiting manner, the remainder of this paragraph details Example 5 of the presently disclosed subject matter. According to Example 5, which encompasses Example 4 above, heating the multi-ply prepreg composite charge 190 (block 538) is performed after reducing the pressure inside the chamber 100 to below atmospheric pressure (block 530) and before expanding the bladder 140 within the chamber 100.

[0033]

[0047] Heating the multi-ply prepreg composite charge 190 prior to inflating the bladder 140 within the chamber 100 serves to degas the multi-ply prepreg composite charge 190. As shown in FIGS. 3A and 3B , the forming tool 130 is not in contact with the multi-ply prepreg composite charge 190 at this stage, and the entire multi-ply prepreg composite charge 190 is either exposed or covered by a permeable component, thereby allowing gas to escape from the multi-ply prepreg composite charge 190. Additionally, heating serves to soften the multi-ply prepreg composite charge 190, thereby facilitating degassing. Finally, heating also serves to shape the multi-ply prepreg composite charge 190, for example, by softening the multi-ply prepreg composite charge 190. However, heating is limited to avoid premature curing of the multi-ply prepreg composite charge 190 (e.g., curing before forming). Specifically, the duration of heating in this stage is minimized by first reducing the pressure inside the chamber 100 and only then commencing heating.

[0034]

[0048] In some embodiments, the multi-ply prepreg composite charge 190 is heated to a temperature and for a duration that does not induce or result in significant curing of the multi-ply prepreg composite charge 190. For example, the multi-ply prepreg composite charge 190 is heated to between about 50% and 80% of the curing temperature during this heating while venting operation.

[0035]

[0049] 1A and 1B, and in particular, for example, to Figures 3A and 3B, the remainder of this paragraph will describe in detail Example 6 of the presently disclosed subject matter. According to Example 6, which encompasses Example 4 above, heating the multi-ply prepreg composite charge 190 (block 538) and reducing the pressure inside the chamber 100 to below atmospheric pressure (block 530) are performed simultaneously prior to expanding the bladder 140 within the chamber 100.

[0036]

[0050] Simultaneously, heating the multi-ply prepreg composite charge 190 and reducing the pressure inside the chamber 100 (to degas the multi-ply prepreg composite charge 190) helps reduce the overall processing time. Additionally, heating (at this stage) helps soften the multi-ply prepreg composite charge 190, thereby facilitating initial degassing and also aids in subsequent shaping of the multi-ply prepreg composite charge 190.

[0037]

[0051] In some embodiments, heating the multi-ply prepreg composite charge 190 and reducing the pressure begin simultaneously. Alternatively, heating the multi-ply prepreg composite charge 190 and reducing the pressure may alternate but overlap. For example, heating the multi-ply prepreg composite charge 190 may begin before reducing the pressure. Alternatively, reducing the pressure may begin before heating the multi-ply prepreg composite charge 190.

[0038]

[0052] 1A and 1B, and in particular, for example, to Figures 3A and 3B, for illustrative purposes only and not in a limiting manner, the remainder of this paragraph will describe in detail Example 7 of the presently disclosed subject matter. According to Example 7, which encompasses any one of Examples 4 through 6 described above, heating the multi-ply prepreg composite charge 190 (block 538) prior to expanding the bladder 140 within the chamber 100 is performed using a heater 150. The bladder 140 is disposed between the heater 150 and the multi-ply prepreg composite charge 190.

[0039]

[0053] Locating the bladder 140 between the heater 150 and the multi-ply prepreg composite charge 190 allows the heater 150 to be separated from the bladder 140, thereby simplifying the overall design of the apparatus. At this stage, the bladder 140 is flattened, and heat is transferred through the two walls of the bladder 140. One of these walls faces the heater 150, and the other faces the multi-ply prepreg composite charge 190. The bladder 140 can also act as a heat spreader, effectively reducing the temperature gradient experienced by the multi-ply prepreg composite charge 190.

[0040]

[0054] In some embodiments, the heater 150 is a stand-alone component. For example, the heater 150 is attached to and / or supported by the chamber housing 110. For example, Figure 3A shows insulation 170 disposed between the chamber housing 110 and the heater 150. Various types of heaters 150 are within the scope, such as resistive heaters and fluid-based heaters.

[0041]

[0055] 1A and 1B, and in particular, for example, to Figures 3C and 3D, for illustrative purposes only and not in a limiting manner, the remainder of this paragraph details Example 8 of the presently disclosed subject matter. According to Example 8, which encompasses any one of Examples 4 through 7 described above, heating the multi-ply prepreg composite charge 190 (block 538) prior to expanding the bladder 140 within the chamber 100 is performed using a bladder surface heater 142 integrated within the bladder 140.

[0042]

[0056] Integrating the bladder surface heater 142 into the bladder 140 reduces the number of components. Furthermore, this integration allows the bladder surface heater 142 to be located close to the multi-ply prepreg composite charge 190 for efficient heating without requiring heat transfer through the walls of the bladder 140. In some embodiments, the bladder surface heater 142 faces the multi-ply prepreg composite charge 190. In some specific embodiments, the bladder surface heater 142 directly contacts the multi-ply prepreg composite charge 190. One embodiment of the bladder surface heater 142 is a resistance heater.

[0043]

[0057] 1A and 1B, and in particular, for example, to Figures 3E and 3F, the remainder of this paragraph details Example 9 of the presently disclosed subject matter. According to Example 9, which encompasses any one of Examples 4 through 7 described above, heating the multi-ply prepreg composite charge 190 (block 538) prior to expanding the bladder 140 within the chamber 100 is performed using a blanket heater 152 disposed between the bladder 140 and the multi-ply prepreg composite charge 190.

[0044]

[0058] The blanket heater 152 is positioned adjacent to the multi-ply prepreg composite charge 190 and during some operational steps, and interacts with the multi-ply prepreg composite charge 190 for efficient heating without requiring heat transfer through the walls of the bladder 140. Separating the blanket heater 152 from the bladder 140 allows for new designs for the blanket heater 152 from the bladder 140. These designs are not limited by the integration of these two components. In some embodiments, the blanket heater 152 faces the multi-ply prepreg composite charge 190. In some specific embodiments, the blanket heater 152 directly contacts the multi-ply prepreg composite charge 190. One embodiment of the blanket heater 152 is a direct resistance heater.

[0045]

[0059] 1A and 1B, and in particular, for example, to Figures 4B and 4C, the remainder of this section will detail Example 10 of the presently disclosed subject matter. According to Example 10, which encompasses Example 9 above, curing multi-ply prepreg composite charge 190 (block 550) includes heating multi-ply prepreg composite charge 190 using blanket heater 152 disposed between multi-ply prepreg composite charge 190 and forming tool 130 (block 552).

[0046]

[0060] The blanket heater 152 provides localized, direct heating to the multi-ply prepreg composite charge 190 without heating other components, particularly bulky components such as the forming tool 130. This direct heating increases processing speed (e.g., by reaching the desired temperature more quickly) and saves energy (e.g., by heating fewer components). Additionally, direct heating eliminates the need for cooling components between processing cycles.

[0047]

[0061] In some embodiments, the blanket heater 152 directly contacts the multi-ply prepreg composite charge 190. In some embodiments, the blanket heater 152 is supported by the forming tool 130, e.g., the blanket heater 152 wraps around the forming tool 130. At the same time, the heating element of the blanket heater 152 is thermally isolated from the forming tool 130. One embodiment of the blanket heater 152 is a direct resistive heater.

[0048]

[0062] 1A and 1B, and in particular, for example, to Figures 4A and 4B, for illustrative purposes only and not in a limiting manner, the remainder of this paragraph details Example 11 of the presently disclosed subject matter. According to Example 11, which includes any one of Examples 1 through 10 described above, inflating bladder 140 within chamber 100 (Block 540) includes fluidly coupling bladder 140 to the atmosphere (Block 542).

[0049]

[0063] Fluidly coupling bladder 140 to the atmosphere does not require complex or additional equipment. Bladder 140 is simply vented to the atmosphere, which causes bladder 140 to expand within chamber 100. Note that the pressure inside chamber 100 is atmospheric pressure, and bladder 140 is pressurized from within bladder 140. For example, a line extending into bladder 140 is connected to a three-way valve, which fluidly couples the interior of bladder 140 to the atmosphere (in this operation) or to a vacuum source (in other operations).

[0050]

[0064] 1A and 1B, and in particular, for example, to Figures 4B and 4C, for illustrative purposes only and not in a limiting manner, the remainder of this paragraph details Example 12 of the presently disclosed subject matter. According to Example 12, which includes any one of Examples 1 through 11 above, curing the multi-ply prepreg composite charge 190 (block 550) includes heating the multi-ply prepreg composite charge 190 using a forming tool heater 132 integrated into a forming tool 130 (block 554).

[0051]

[0065] While the multi-ply prepreg composite charge 190 is curing, the multi-ply prepreg composite charge 190 conforms to and is pressed against the forming tool 130, thereby ensuring good heat transfer between the multi-ply prepreg composite charge 190 and the forming tool 130. The use of the forming tool 130, or more specifically, the forming tool heater 132 incorporated within the forming tool 130, is utilized in response to the heat transfer between the multi-ply prepreg composite charge 190 and the forming tool 130. Furthermore, in some embodiments, the forming tool 130 is preheated prior to contacting the multi-ply prepreg composite charge 190. This preheating feature reduces overall processing time by eliminating heating time.

[0052]

[0066] In some embodiments, the forming tool heater 132 is a resistive heater. However, other types of heaters are within the scope of this disclosure. In some embodiments, the forming tool heater 132 is disposed adjacent to a surface of the forming tool 130. This surface contacts the multi-ply prepreg composite charge 190. Furthermore, the forming tool heater 132 is uniformly distributed along this surface. For example, the forming tool heater 132 may include multiple heating elements, as shown, for example, in FIG. 4C.

[0053]

[0067] 1A and 1B, and in particular, for example, to Figures 4B, 4C, 4D, and 4E, for illustrative purposes only and not in a limiting manner, the remainder of this paragraph details Example 13 of the presently disclosed subject matter. According to Example 13, which includes any one of Examples 1 through 12 above, curing multi-ply prepreg composite charge 190 (block 550) includes heating multi-ply prepreg composite charge 190 using bladder 140 (block 556).

[0054]

[0068] While multi-ply prepreg composite charge 190 is curing, multi-ply prepreg composite charge 190 conforms to and is pressed by bladder 140, thereby ensuring good heat transfer between multi-ply prepreg composite charge 190 and bladder 140. Furthermore, by using bladder 140 as a heating source, it is not necessary to heat other components, especially bulky components such as forming tool 130, thereby increasing the overall processing speed.

[0055]

[0069] In some embodiments, the bladder 140 is heated using an integrated heater. Alternatively, the bladder 140 is heated by supplying hot air into the bladder 140. For example, air is heated outside the bladder 140 and then introduced into the bladder 140.

[0056]

[0070] 1A and 1B, and in particular, for example, to Figures 4B and 4C, the remainder of this paragraph details Example 14 of the presently disclosed subject matter. According to Example 14, which encompasses Example 13 above, heating multi-ply prepreg composite charge 190 using bladder 140 (block 556) includes heating multi-ply prepreg composite charge 190 using bladder surface heater 142 integrated within bladder 140 (block 557).

[0057]

[0071] While multi-ply prepreg composite charge 190 is curing, multi-ply prepreg composite charge 190 conforms to and is pressed by bladder 140, thereby ensuring good heat transfer between multi-ply prepreg composite charge 190 and bladder 140. For example, bladder surface heater 142 is disposed on the surface of bladder 140 that contacts multi-ply prepreg composite charge 190. Furthermore, by using bladder 140 as a heating source, it is not necessary to heat other components, especially bulky components such as forming tool 130, thereby increasing overall processing speed.

[0058]

[0072] In some embodiments, bladder surface heater 142 is a resistive heater, although other types of heaters are within the scope of this disclosure. In some embodiments, bladder surface heater 142 is integrated into bladder 140, e.g., forms a surface of bladder 140.

[0059]

[0073] 1A and 1B, and in particular, for example, to Figures 4D and 4E, for illustrative purposes only and not in a limiting manner, the remainder of this paragraph details Example 15 of the presently disclosed subject matter. According to Example 15, which encompasses Example 13 above, heating the multi-ply prepreg composite charge 190 using a bladder 140 (block 556) includes introducing hot air into the bladder 140 (block 558).

[0060]

[0074] While the multi-ply prepreg composite charge 190 is curing, the multi-ply prepreg composite charge 190 conforms to and is pressed by the bladder 140, thereby ensuring good heat transfer between the multi-ply prepreg composite charge 190 and the bladder 140. Introducing hot air into the bladder 140 results in uniform heating of the bladder 140, and this heat transfer also results in uniform heating of the multi-ply prepreg composite charge 190. In some embodiments, air is heated outside the bladder 140 and then introduced into the bladder 140.

[0061]

[0075] 1A and 1B, and in particular, for example, to FIGS. 4D and 4E, for illustrative purposes only and not in a limiting manner, the remainder of this paragraph will describe in detail Example 16 of the presently disclosed subject matter. According to Example 16, which encompasses Example 15 described above, after expanding bladder 140 within chamber 100 by increasing the pressure inside bladder 140 to atmospheric pressure (block 540), bladder 140 includes first bladder space 148 and second bladder space 149. Thus, forming tool 130 is positioned between first bladder space 148 and second bladder space 149. The step of introducing hot air into bladder 140 (block 558) includes recirculating the hot air between first bladder space 148 and second bladder space 149 (block 559).

[0062]

[0076] By recirculating the hot air between the first bladder space 148 and the second bladder space 149 of the bladder 140, a closed-loop system has been established that is more energy efficient than a system that continuously draws more air from the environment. Additionally, by recirculating the hot air between the first bladder space 148 and the second bladder space 149, a uniform temperature distribution within the bladder 140 and, as a result, over the multi-ply prepreg composite charge 190 is ensured.

[0063]

[0077] In some embodiments, additional air is supplied to or removed from bladder 140 based on the pressure within bladder 140, which pressure is monitored. For example, the pressure inside bladder 140 is maintained at atmospheric pressure levels.

[0064]

[0078] 1A and 1B, and in particular, for example, to Figures 4D and 4E, for illustrative purposes only and not in a limiting manner, the remainder of this paragraph will describe in detail Example 17 of the presently disclosed subject matter. According to Example 17, which encompasses Example 16 described above, recirculating hot air between first bladder space 148 and second bladder space 149 (block 559) is performed using thermal module 182 fluidly coupled to first bladder space 148 and second bladder space 149.

[0065]

[0079] Thermal module 182 ensures that the temperature of the hot air recirculated between first bladder space 148 and second bladder space 149 is at a set point. For example, the air is cooled as it travels through bladder 140 (e.g., through either first space 148 or second space 149), heating the walls of bladder 140 and providing heat to multi-ply prepreg composite charge 190. As the air leaves bladder 140, thermal module 182 reheats the air to return it to the set point.

[0066]

[0080] In some embodiments, the thermal module 182 is equipped with a heater (e.g., a resistive heater). Additionally, in some embodiments, the thermal module 182 is equipped with a blower for pushing hot air and recirculating the hot air between the first bladder space 148 and the second bladder space 149 of the bladder 140.

[0067]

[0081] 1A and 1B, and in particular, for example, FIG. 4D, the remainder of this paragraph will describe in detail Example 18 of the presently disclosed subject matter. According to Example 18, which encompasses Example 17 above, first bladder space 148 is fluidly coupled to second bladder space 149 via duct 185 external to bladder 140.

[0068]

[0082] Duct 185 fluidly couples first bladder space 148 to second bladder space 149 and ensures that hot air can be recirculated between first bladder space 148 and second bladder space 149 of bladder 140.

[0069]

[0083] In some embodiments, ducts 185 protrude into each of first bladder space 148 and second bladder space 149. Additionally, ducts 185 extend outside of chamber 100 to avoid interference with bladders 140 and other components.

[0070]

[0084] 1A and 1B, and in particular, for example, FIG. 4A, the remainder of this paragraph will describe in detail Example 19 of the presently disclosed subject matter. According to Example 19, which encompasses Examples 17 or 18 described above, first bladder space 148 is fluidly coupled to second bladder space 149 via passageway 141 inside bladder 140.

[0071]

[0085] Passageway 141 fluidly couples first bladder space 148 to second bladder space 149, ensuring that hot air can be recirculated between first bladder space 148 and second bladder space 149 of bladder 140. Additionally, passageway 141 heats a portion of bladder 140 and extends between first bladder space 148 and second bladder space 149, thereby ensuring that all surfaces of multi-ply prepreg composite charge 190 are heated.

[0072]

[0086] In some embodiments, the height of the passages 141 is the same as the gap between the multi-ply prepreg composite charge 190 and the forming tool 130. Thus, the height of the passages 141 is dictated by the design of the forming tool 130. In some embodiments, the height of the passages 141 varies along the length of the chamber (X direction) to ensure a uniform flow of hot air through the passages 141.

[0073]

[0087] 1A and 1B, and in particular, for example, FIG. 4E, the remainder of this paragraph will describe in detail Example 20 of the presently disclosed subject matter. According to Example 20, which encompasses Example 16 described above, recirculating hot air between first bladder space 148 and second bladder space 149 (Block 559) is performed using a thermal module 182 fluidly coupled to first bladder space 148 and second bladder space 149, and a second thermal module 183 fluidly coupled to first bladder space 148 and second bladder space 149.

[0074]

[0088] Thermal module 182 and second thermal module 183 ensure that the temperature of the hot air recirculated between first bladder space 148 and second bladder space 149 is at a set point. For example, the air is cooled as it travels through bladder 140 (e.g., through either first space 148 or second space 149), heating the walls of bladder 140 and providing heat to multi-ply prepreg composite charge 190. As the air leaves first bladder space 148, second thermal module 183 reheats the air back to the set point before recirculating it into second bladder space 149. Similarly, as the air leaves second bladder space 149, thermal module 182 reheats the air back to the set point before recirculating it into first bladder space 148.

[0075]

[0089] In some embodiments, the thermal module 182 and the second thermal module 183 are each equipped with a heater (e.g., a resistive heater). Additionally, in some embodiments, the thermal module 182 and the second thermal module 183 are each equipped with a blower for pushing hot air and recirculating the hot air between the first bladder space 148 and the second bladder space 149 of the bladder 140.

[0076]

[0090] 1A and 1B, and in particular, for example, to Figures 4A and 4E, for illustrative purposes only and not in a limiting manner, the remainder of this paragraph will describe in detail Example 21 of the presently disclosed subject matter. According to Example 21, which encompasses any one of Examples 16 to 19 described above, introducing hot air into bladder 140 (block 558) includes distributing the hot air into bladder 140 through first bladder duct 144 disposed inside first bladder space 148 and through second bladder duct 146 disposed inside second bladder space 149 (block 560).

[0077]

[0091] The first bladder duct 144 and the second bladder duct 146 control the distribution of hot air within the bladder 140, thereby reducing overall heating and energy consumption of the tool. In some embodiments, the first bladder duct 144 and the second bladder duct 146 are each perforated tubes.

[0078]

[0092] 1A and 1B, and in particular, for example, Figures 4A and 4E, the remainder of this section will describe in detail Example 22 of the presently disclosed subject matter. According to Example 22, which encompasses Example 21 described above, hot air is directed toward a multi-ply prepreg composite charge 190 by first bladder duct 144 and second bladder duct 146.

[0079]

[0093] The first bladder duct 144 and the second bladder duct 146 control the distribution of hot air within the bladder 140, thereby reducing overall tool heating and energy consumption. In some embodiments, the first bladder duct 144 and the second bladder duct 146 are each perforated tubes that direct hot air toward the multi-ply prepreg composite charge 190 to cure the multi-ply prepreg composite charge 190.

[0080]

[0094] 1A and 1B, and in particular, for example, Figures 4A and 4E, the remainder of this paragraph will describe in detail Example 23 of the presently disclosed subject matter. According to Example 23, which encompasses Example 22 described above, first bladder duct 144 includes first bladder duct opening 145, and second bladder duct 146 includes second bladder duct opening 147. These openings are included only in those corresponding portions of first bladder duct 144 and second bladder duct 146 that face multi-ply prepreg composite charge 190 when hot air is distributed within bladder 140.

[0081]

[0095] The first bladder duct 144 and the second bladder duct 146 control the distribution of hot air within the bladder 140, thereby reducing overall tool heating and energy consumption. In some embodiments, the first bladder duct 144 and the second bladder duct 146 are each perforated tubes. Specifically, the perforations in the first bladder duct 144 are represented by first bladder duct openings 145. The perforations in the second bladder duct 146 are represented by second bladder duct openings 147.

[0082]

[0096] 1A and 1B, and in particular, for example, to Figures 4A and 4F, the remainder of this paragraph will describe in detail Example 24 of the presently disclosed subject matter. According to Example 24, which encompasses any one of Examples 21 to 23 described above, reducing the pressure inside bladder 140 to below atmospheric pressure (Block 530) includes collapsing first bladder duct 144 and second bladder duct 146 (Block 536).

[0083]

[0097] Collapsing the first bladder duct 144 and the second bladder duct 146 ensures that the first bladder duct 144 and the second bladder duct 146 do not interfere with the operation of the bladder 140 when the multi-ply prepreg composite charge 190 is placed in the chamber 100. In some embodiments, the bladder 140 is substantially flat when the multi-ply prepreg composite charge 190 is placed in the chamber 100.

[0084]

[0098] 1A and 1B, and in particular, for example, to FIG. 4E, the remainder of this paragraph will describe in detail Example 25 of the presently disclosed subject matter. According to Example 25, which encompasses any one of Examples 21 to 24 described above, distributing hot air into bladder 140 through first bladder duct 144 disposed inside first bladder space 148 and through second bladder duct 146 disposed inside second bladder space 149 (block 560) includes supplying hot air into first bladder duct 144 using thermal module 182 and supplying hot air into second bladder duct 146 using second thermal module 183 (block 562).

[0085]

[0099] Thermal module 182 and second thermal module 183 ensure that the temperature of the hot air recirculated between first bladder space 148 and second bladder space 149 is at a set point. For example, the air is cooled as it travels through bladder 140 (e.g., through either first space 148 or second space 149), heating the walls of bladder 140 and providing heat to multi-ply prepreg composite charge 190. As the air leaves first bladder space 148, second thermal module 183 reheats the air back to the set point before recirculating it into second bladder space 149. Similarly, as the air leaves second bladder space 149, thermal module 182 reheats the air back to the set point before recirculating it into first bladder space 148.

[0086]

[0100] In some embodiments, the thermal module 182 and the second thermal module 183 are each equipped with a heater (e.g., a resistive heater). Additionally, in some embodiments, the thermal module 182 and the second thermal module 183 are each equipped with a blower for pushing hot air and recirculating the hot air between the first bladder space 148 and the second bladder space 149 of the bladder 140.

[0087]

[0101] 1A and 1B, and in particular, for example, FIG. 4E, the remainder of this paragraph will describe in detail Example 26 of the presently disclosed subject matter. According to Example 26, which encompasses Example 25 described above, distributing hot air into bladders 140 through first bladder duct 144 disposed inside first bladder space 148 and through second bladder duct 146 disposed inside second bladder space 149 (block 560) further includes recirculating the hot air from first bladder space 148 into second thermal module 183 and recirculating the hot air from second bladder space 149 into thermal module 182 (block 564).

[0088]

[0102] Thermal module 182 and second thermal module 183 ensure that the temperature of the hot air recirculated between first bladder space 148 and second bladder space 149 is at a set point. For example, the air is cooled as it travels through bladder 140 (e.g., through either first space 148 or second space 149), heating the walls of bladder 140 and providing heat to multi-ply prepreg composite charge 190. As the air leaves first bladder space 148, second thermal module 183 reheats the air back to the set point before recirculating it into second bladder space 149. Similarly, as the air leaves second bladder space 149, thermal module 182 reheats the air back to the set point before recirculating it into first bladder space 148.

[0089]

[0103] In some embodiments, the thermal module 182 and the second thermal module 183 are each equipped with a heater (e.g., a resistive heater). Additionally, in some embodiments, the thermal module 182 and the second thermal module 183 are each equipped with a blower for pushing hot air and recirculating the hot air between the first bladder space 148 and the second bladder space 149 of the bladder 140.

[0090]

[0104] 1A and 1B, and in particular, for example, FIG. 4B, the remainder of this paragraph details Example 27 of the presently disclosed subject matter. According to Example 27, which encompasses Example 26 above, method 500 also includes cooling multi-ply prepreg composite charge 190 (block 570) after curing multi-ply prepreg composite charge 190 (block 550).

[0091]

[0105] Cooling the multi-ply prepreg composite charge 190 ensures that the multi-ply prepreg composite charge 190 maintains the second shape after, for example, the bladder 140 no longer supports the multi-ply prepreg composite charge 190. In some embodiments, the multi-ply prepreg composite charge 190 cools while the multi-ply prepreg composite charge 190 is compressed between the bladder 140 and the forming tool 130; more specifically, the multi-ply prepreg composite charge 190 remains formed into the second shape by the forming tool 130 while cooling.

[0092]

[0106] 1A and 1B, and in particular, for example, to Figures 4D and 4E, for illustrative purposes only and not in a limiting manner, the remainder of this section details Example 28 of the presently disclosed subject matter. According to Example 28, which encompasses Example 27 above, cooling multi-ply prepreg composite charge 190 (block 570) includes flowing chilled air into bladder 140 (block 572).

[0093]

[0107] Flowing chilled air into bladder 140 ensures uniform cooling of bladder 140 and, consequently, uniform cooling of multi-ply prepreg composite charge 190. Uniform cooling of multi-ply prepreg composite charge 190 helps relieve thermal stresses and prevent distortion within multi-ply prepreg composite charge 190. In some embodiments, the temperature of the chilled air introduced into bladder 140 is gradually reduced to ensure gradual cooling.

[0094]

[0108] 1A and 1B, and in particular, for example, FIG. 4E, the remainder of this paragraph will describe in detail Example 29 of the presently disclosed subject matter. According to Example 29, which encompasses Example 28 described above, flowing chilled air into bladder 140 (block 572) is performed using thermal module 182 and second thermal module 183.

[0095]

[0109] Thermal module 182 and second thermal module 183 ensure that the temperature of the cooled air introduced into bladder 140 is at a set point (e.g., a gradually reduced set point). For example, as the air moves through bladder 140, it is heated, cooling the walls of bladder 140 and cooling multi-ply prepreg composite charge 190. As the air leaves first bladder space 148, second thermal module 183 cools the air back to the set point before recirculating it into second bladder space 149. Similarly, as the air leaves second bladder space 149, thermal module 182 cools the air back to the set point before recirculating it into first bladder space 148.

[0096]

[0110] In some embodiments, the thermal module 182 and the second thermal module 183 are each equipped with a cooler. Additionally, in some embodiments, the thermal module 182 and the second thermal module 183 are each equipped with a blower for recirculating cooled air between the first bladder space 148 and the second bladder space 149 of the bladder 140.

[0097]

[0111] 1A and 1B, and in particular, for example, to Figures 3A, 3B, 3C, and 3D, for illustrative purposes only and not in a limiting manner, the remainder of this paragraph details Example 30 of the presently disclosed subject matter. According to Example 30, which includes any one of Examples 1 through 29 described above, method 500 further includes disposing multi-ply prepreg composite charge 190 between porous separator films 160 (block 512) prior to disposing multi-ply prepreg composite charge 190 in chamber 100 (block 520).

[0098]

[0112] The porous separator film 160 prevents the multi-ply prepreg composite charge 190 from sticking to other components while allowing the multi-ply prepreg composite charge 190 to degas. Specifically, when the pressure inside the chamber 100 is reduced below atmospheric pressure, the porous film 160 allows gas to escape from the multi-ply prepreg composite charge 190. In some embodiments, a sheet of the porous separator film 160 is disposed between the multi-ply prepreg composite charge 190 and the bladder 140. In one or more embodiments, another sheet of the porous separator film 160 is disposed between the multi-ply prepreg composite charge 190 and the forming tool 130.

[0099]

[0113] 1A and 1B, and in particular, for example, FIG. 4B, the remainder of this paragraph details Example 31 of the presently disclosed subject matter. According to Example 31, which includes any one of Examples 1 through 25 described above, method 500 also includes cooling multi-ply prepreg composite charge 190 (block 570) after curing multi-ply prepreg composite charge 190.

[0100]

[0114] Cooling the multi-ply prepreg composite charge 190 ensures that the multi-ply prepreg composite charge 190 maintains the second shape after, for example, the bladder 140 no longer supports the multi-ply prepreg composite charge 190. In some embodiments, the multi-ply prepreg composite charge 190 cools while the multi-ply prepreg composite charge 190 is compressed between the bladder 140 and the forming tool 130; more specifically, the multi-ply prepreg composite charge 190 remains constructed into the second shape by the forming tool 130 while cooling.

[0101]

[0115] 1A and 1B, and in particular, for example, to Figures 4D and 4E, for illustrative purposes only and not in a limiting manner, the remainder of this section will describe in detail Example 32 of the presently disclosed subject matter. According to Example 32, which encompasses Example 31 above, cooling multi-ply prepreg composite charge 190 (block 570) includes flowing chilled air into bladder 140 (block 572).

[0102]

[0116] Flowing chilled air into bladder 140 ensures uniform cooling of bladder 140 and, consequently, uniform cooling of multi-ply prepreg composite charge 190. Uniform cooling of multi-ply prepreg composite charge 190 helps relieve thermal stresses and prevent distortion within multi-ply prepreg composite charge 190. In some embodiments, the temperature of the chilled air introduced into bladder 140 is gradually reduced to ensure gradual cooling.

[0103]

[0117] 1A and 1B, and in particular, for example, FIG. 4E, the remainder of this paragraph will describe in detail Example 33 of the presently disclosed subject matter. According to Example 33, which encompasses Example 32 described above, flowing chilled air into bladder 140 (block 572) is performed using thermal module 182 fluidly coupled to bladder 140.

[0104]

[0118] Thermal module 182 and second thermal module 183 ensure that the temperature of the cooled air introduced into bladder 140 is at a set point (e.g., a gradually reduced set point). For example, as the air moves through bladder 140, it is heated, cooling the walls of bladder 140 and cooling multi-ply prepreg composite charge 190. As the air leaves first bladder space 148, second thermal module 183 cools the air back to the set point before recirculating it into second bladder space 149. Similarly, as the air leaves second bladder space 149, thermal module 182 cools the air back to the set point before recirculating it into first bladder space 148.

[0105]

[0119] In some embodiments, the thermal module 182 and the second thermal module 183 are each equipped with a cooler. Additionally, in some embodiments, the thermal module 182 and the second thermal module 183 are each equipped with a blower for recirculating cooled air between the first bladder space 148 and the second bladder space 149 of the bladder 140.

[0106]

[0120] 1A and 1B, and in particular, for example, to Figures 8 and 9, the remainder of this paragraph details Example 34 of the presently disclosed subject matter. According to Example 34, which includes any one of Examples 1 through 33 described above, chamber 100 is configured to form composite part 195 from multi-ply prepreg composite charge 190 using multiple steps of method 500.

[0107]

[0121] The chamber 100 allows for a specific sequence of operations to be performed. The specific sequence of operations includes degassing the multi-ply prepreg composite charge 190 before forming the multi-ply prepreg composite charge 190. Specifically, degassing is performed while at least a portion of the multi-ply prepreg composite charge 190 is exposed. At this stage, the multi-ply prepreg composite charge 190 has not yet been compressed between the bladder 140 and the forming tool 130. If the multi-ply prepreg composite charge 190 were compressed between the bladder 140 and the forming tool 130, the efficiency of degassing would decrease because the gas path would be blocked by the bladder 140 and the forming tool 130.

[0108]

[0122] When the pressure inside the chamber 100 is reduced below atmospheric pressure, the multi-ply prepreg composite charge 190 is exposed to the environment inside the chamber 100, which results in degassing of the multi-ply prepreg composite charge 190. Note that the multi-ply prepreg composite charge 190 is initially placed into the chamber 100 while the chamber 100 is at atmospheric pressure. This degassing is performed for a period of time, which depends on various factors, such as the thickness of the multi-ply prepreg composite charge 190, the material properties (e.g., porosity, density, elasticity) of the multi-ply prepreg composite charge 190, and the level of degassing required. In some embodiments, the duration of the degassing is between 1 minute and 1 hour, or more specifically, between 5 minutes and 30 minutes.

[0109]

[0123] An embodiment of the subject matter disclosed herein may be described in the context of an aircraft manufacturing and service method 900 shown in FIG. 6 and an aircraft 902 shown in FIG. 7. During pre-production, method 900 may include specification and design of aircraft 902 (block 904) and material procurement (block 906). During production, component and subassembly manufacturing (depicted at block 908) and system integration (depicted at block 910) of aircraft 902 may occur. Aircraft 902 may then undergo certification and delivery (depicted at block 912) and be placed into service (depicted at block 914). During its operational life, aircraft 902 may be scheduled for routine maintenance and service (depicted at block 916). The routine maintenance and service may include modification, reconfiguration, refurbishment, etc. of one or more systems of aircraft 902.

[0110]

[0124] Each of the steps of method 900 may be performed or carried out by a system integrator, a third party, and / or an operator (e.g., a customer). For purposes of this specification, a system integrator may include, but is not limited to, any number of aircraft manufacturers and major system subcontractors, a third party may include, but is not limited to, any number of vendors, subcontractors, and suppliers, and an operator may be an airline, a leasing company, a military organization, a service organization, etc.

[0111]

[0125] As shown in FIG. 7 , aircraft 902 produced by method 900 may include an airframe 918 having multiple high-level systems 920 and an interior 922. Examples of high-level systems 920 include one or more of a propulsion system 924, an electrical system 926, a hydraulic system 928, and an environmental system 930. Any number of other systems may be included. While an aerospace example is provided, the principles disclosed herein may be applied to other industries, such as the automotive industry. As such, the principles disclosed herein may be applied to other vehicles, such as land vehicles, marine vehicles, space vehicles, etc., in addition to aircraft 902.

[0112]

[0126] The apparatus and methods shown and described herein may be used during any one or more stages of method 900. For example, components or subassemblies corresponding to component and subassembly manufacturing (block 908) may be fabricated or manufactured in a manner similar to components or subassemblies manufactured during the operation of aircraft 902 (block 914). Also, one or more embodiments of the apparatus(es), method(s), or combinations thereof may be utilized during the manufacturing stage (illustrated by blocks 908 and 910), for example, by substantially streamlining or reducing the cost of assembling aircraft 902. Similarly, one or more embodiments implementing an apparatus or method, or combinations thereof, may be utilized during the operation of aircraft 902 (block 914) and / or during maintenance and service (block 916), by way of example and not limitation.

[0113]

[0127] The various embodiments of the device(s) and method(s) disclosed herein include a wide variety of components, features, and functions. It should be understood that it is contemplated that the various examples of the device(s) and method(s) disclosed herein may include any of the components, features, and functions of any of the other example device(s) and method(s) disclosed herein, in any combination.

[0114]

[0128] Many modifications of the embodiments set forth herein will come to mind to one skilled in the art having the benefit of the teachings presented in the foregoing descriptions and the accompanying drawings.

[0115]

[0129] It is therefore to be understood that the subject matter disclosed herein is not limited to the particular examples illustrated, and that modifications and other examples are intended to be included within the scope of the appended claims. Moreover, while the above description and related drawings describe examples of the subject matter disclosed herein in terms of certain illustrative combinations of elements and / or functions, it should be recognized that alternative implementations may provide various combinations of elements and / or functions without departing from the scope of the appended claims. Accordingly, reference numerals placed in parentheses in the appended claims are provided for purposes of illustration and are not intended to limit the scope of the claimed subject matter to the particular examples provided herein.

[0116]

[0130] Although the foregoing concepts have been described in some detail for purposes of clarity of understanding, it will be apparent that certain changes and modifications may be practiced within the scope of the appended claims. It should be noted that there are many alternative ways of implementing the processes, systems, and apparatus. Accordingly, the examples herein should be considered illustrative and not limiting.

Claims

1. A method (500) of forming a composite part (195) from a multi-ply prepreg composite charge (190), comprising: reducing the pressure inside a bladder (140) located in a chamber (100) at atmospheric pressure to below said atmospheric pressure; placing the multi-ply prepreg composite charge (190) having a first shape within the chamber (100); reducing the pressure inside the chamber (100) to below atmospheric pressure; Inflating the bladder (140) within the chamber (100) by increasing the pressure inside the bladder (140) to the atmospheric pressure while maintaining the pressure inside the chamber (100) below the atmospheric pressure, thereby The multi-ply prepreg composite charge (190) is compressed between the bladder (140) and a forming tool (130) positioned inside the chamber (100); forming the multi-ply prepreg composite charge (190) by the forming tool (130) into a second shape different from the first shape; and curing the multi-ply prepreg composite charge (190) having the second shape; The method (500), wherein during the step of reducing the pressure inside the chamber (100) to below atmospheric pressure, the multi-ply prepreg composite charge (190) is separated from the forming tool (130) by a gap (134).

2. The chamber (100) comprises a chamber housing (110) and a chamber lid (120) coupled to the chamber housing (110) and pivotable relative to the chamber housing (110); the steps of reducing the pressure inside the chamber (100) to less than atmospheric pressure and expanding the bladder (140) within the chamber (100) by increasing the pressure inside the bladder (140) to atmospheric pressure while maintaining the pressure inside the chamber (100) less than atmospheric pressure each include providing a seal between the chamber lid (120) and the chamber housing (110); The method (500) of claim 1, wherein the forming tool (130) is attached to and supported by the chamber lid (120).

3. 3. The method (500) of claim 1 or 2, further comprising the step of heating the multi-ply prepreg composite charge (190) prior to the step of expanding the bladder (140) within the chamber (100).

4. 4. The method of claim 3, wherein the step of heating the multi-ply prepreg composite charge before the step of expanding the bladder within the chamber is performed after the step of reducing the pressure inside the chamber to below atmospheric pressure.

5. 4. The method of claim 3, wherein the steps of heating the multi-ply prepreg composite charge and reducing the pressure inside the chamber to below atmospheric pressure are performed simultaneously before the step of expanding the bladder within the chamber.

6. the step of heating the multi-ply prepreg composite charge (190) prior to the step of expanding the bladder (140) within the chamber (100) is performed using a heater (150); The method (500) of any one of claims 3 to 5, wherein the bladder (140) is disposed between the heater (150) and the multi-ply prepreg composite charge (190).

7. 7. The method (500) of any one of claims 3 to 6, wherein the step of heating the multi-ply prepreg composite charge (190) prior to the step of expanding the bladder (140) in the chamber (100) is performed using a bladder surface heater (142) integrated into the bladder (140).

8. 7. The method (500) of any one of claims 3 to 6, wherein the step of heating the multi-ply prepreg composite charge (190) prior to the step of expanding the bladder (140) within the chamber (100) is performed using a blanket heater (152) positioned between the forming tool (130) and the multi-ply prepreg composite charge (190).

9. 10. The method (500) of claim 8, wherein the step of curing the multi-ply prepreg composite charge (190) comprises heating the multi-ply prepreg composite charge (190) using the blanket heater (152) disposed between the multi-ply prepreg composite charge (190) and the forming tool (130).

Images