Molding apparatus and method for forming highly contoured composite structures - Patents.com

Abstract

To provide an improved forming apparatus and method for preventing wrinkles and distortion of a composite structure.SOLUTION: There is provided a forming apparatus, the forming apparatus is configured in that: a forming apparatus (10) includes a first die (54) and a second die (64); has a pair of first die portions (56) that define a die cavity (58) apart from each other; a composite forming material is formed into a contouring hat portion having a cap in the die cavity; the forming apparatus also includes a restraint assembly (60) having a restraint device (62) disposed in the die cavity; the restraint device is designed to prevent wrinkles in the cap by restraining a cap portion, and when the contouring hat portion is formed, and applying an upward resistance force to the cap portion and to a downward pressing force applied by the second die; and the restraint assembly has a retaining element (96) for holding the restraint device.SELECTED DRAWING: Figure 2B

Description

[Technical field]

[0001] The present disclosure relates generally to the manufacture of composite structures such as those used in the aircraft industry, and more particularly to an apparatus and method for forming flat composite blanks into highly contoured composite structures, such as structural members including stringers and stiffeners. [Background technology]

[0002] Composite structures are used in a variety of applications, including aircraft manufacturing, due to their high strength-to-weight ratio, corrosion resistance, and other favorable properties. In particular, in aircraft manufacturing, composite structures may be used to form the fuselage, wings, tails, and other portions of the aircraft. Such composite structures are formed from composite laminates that include multiple composite plies or layers that are overlapped with one another.

[0003] Composite structural members, such as stringers and stiffeners, may require complex contours for a particular application and may be formed using a forming apparatus having male and female dies that can compress a flat composite laminate feedstock to shape it into a desired composite structure that is contoured or highly contoured along its length.

[0004] Known forming apparatus and methods exist for forming flat composite laminate feedstock into highly contoured composite structures, such as stringers. However, in these known forming apparatus and methods, where the stringers are contoured along their length as part of the forming process, localized stresses are generated in the composite feedstock during forming that may result in wrinkling or buckling in the areas of the stringers where these stresses are generated. In the case of contoured stringers having a hat-shaped cross section, i.e. highly contoured stringers, stresses are generated in the contoured areas of the stringers that tend to form wrinkling or buckling in the stringer caps, which may result in wrinkling or fiber distortion in the stringer caps. Such wrinkling or buckling of the caps is undesirable as it may affect the structural performance of the stringers and may result in the need to rework the stringers or change the stringer design, which may result in significant production downtime, increased labor, and / or increased material costs.

[0005] Furthermore, known methods for producing highly contoured structural members, such as stringers, using flat composite laminate stock to reduce the likelihood of wrinkling or buckling may be limited to hand layup techniques in which each ply is laid up manually onto a die or other tool, which can be laborious and time consuming, increasing manufacturing costs.

[0006] Thus, there is a need for an apparatus and method for forming highly contoured composite structures, such as structural members, including stringers and reinforcing members, that prevents or substantially prevents wrinkling and buckling in contoured areas, such as caps, does not use hand layup techniques, and has advantages over known apparatus and methods. Summary of the Invention

[0007] In exemplary embodiments of the present disclosure, improved molding apparatus and methods are provided for forming highly contoured composite structures, such as stringers, using a restraint assembly in a first, or female, die to prevent or substantially prevent wrinkle formation and fiber distortion in the highly contoured composite structures, such as stringers. As described in the detailed description below, embodiments of the improved molding apparatus and methods can have significant advantages over existing apparatus and methods.

[0008] In an embodiment of the present disclosure, a molding apparatus is provided for constraining a composite material and forming the composite material into a highly contoured composite structure. The molding apparatus includes a first die and a second die between which the composite material is formed. The first die has a pair of first die portions spaced apart to define a die cavity in which the composite material is formed into a contoured hat portion having a cap. The pair of first die portions are slidably displaceable relative to one another. The second die has a tapered portion designed to be at least partially inserted into the die cavity.

[0009] The molding apparatus further includes a constraint assembly coupled to the first die and having a constraint device disposed in the die cavity, the constraint device designed to constrain a cap portion of the composite molding blank between the constraint device and the second die and to prevent wrinkles in the cap by exerting an upward resistance force against the cap portion and against a downward force exerted by the second die when the contoured hat portion is formed, and the constraint assembly further includes a retention element designed to retain the constraint device when the second die retracts after the highly contoured composite structure is formed.

[0010] In another embodiment of the present disclosure, a method is provided for constraining a composite molding feedstock and forming the composite molding feedstock into a highly contoured composite structure. The method includes disposing a composite laminate molding feedstock between and in contact with a first die and a second die of a molding apparatus. The first die has a pair of first die portions spaced apart from one another to define a die cavity. The first die further includes a constraint assembly including a constraint device disposed in the die cavity.

[0011] The method further includes forcing the composite molding material into the die cavity of the molding apparatus to form a contoured hat portion having a cap and sides. The method further includes constraining the cap using the constraining device as the contoured hat portion is formed and using the constraining device to exert an upward resistive force on the cap and against a downward force exerted by the second die to relieve stress from the cap and prevent wrinkles in the cap.

[0012] The method further includes forming a highly contoured composite structure having the cap without wrinkles.The method further includes holding the constraining device using a holding element of the constraining assembly to prevent the constraining device from pushing up on the highly contoured composite structure as the second die retracts.

[0013] In another embodiment of the present disclosure, a method for forming an aircraft stringer having a wrinkle-free cap is provided, the method including disposing a composite laminate molding feedstock between and in contact with a female die and a male die of a highly contoured stringer forming apparatus, the female die having a pair of die blocks spaced apart from one another to define a die cavity, and the female die further having a restraint assembly including a restraint device disposed in the die cavity.

[0014] The method further includes forcing the composite laminate feedstock into the die cavity of the highly contoured stringer forming apparatus to form a contoured hat portion for the aircraft stringer, the contoured hat portion having a cap and a side portion, and the method further includes constraining the cap using the restraining device as the contoured hat portion is formed and using the restraining device to exert an upward resistive force on the cap and against a downward pushing force exerted by the second die to relieve stress from the cap and prevent wrinkles in the cap.

[0015] The method further includes forming a remainder of the composite laminate feedstock into the aircraft stringer while the restraining device continues to apply the upward resistance force against the cap and against the downward force while restraining the cap. The method further includes forming the aircraft stringer with the cap free of wrinkles.

[0016] The method further includes retracting the male die from the aircraft stringer. The method further includes holding the restraining device using a retention element of the restraining assembly to prevent the restraining device from pushing up on the aircraft stringer as the male die retracts. The method further includes removing the aircraft stringer from the female die. The method further includes releasing the retention element.

[0017] The above-mentioned features, functions, and advantages may be realized individually in various embodiments of the present disclosure and may be combined with each other in other embodiments, as will become apparent from the following description and drawings. [Brief description of the drawings]

[0018] The present disclosure will be better understood from the following detailed description in conjunction with the accompanying drawings, which depict preferred and exemplary embodiments and are not necessarily to scale, and which are intended as examples only and are not intended to limit the scope of the present description or claims.

[0019] [Figure 1A] FIG. 1 is a functional block diagram illustrating an exemplary embodiment of a molding apparatus of the present disclosure. [Figure 1B] FIG. 1B is a functional block diagram illustrating an exemplary embodiment of a restraint assembly usable in the molding apparatus shown in FIG. 1A. [Figure 2A] FIG. 2 is a front perspective view of an exemplary embodiment of a molding apparatus of the present disclosure showing a restraint assembly at a first die and a portable carrier portion separated from the molding machine portion. [Figure 2B] FIG. 2B is a front perspective view of the molding apparatus of FIG. 2A showing the portable carrier portion coupled to the molding machine portion and the first and second dies in an open position ready to receive a composite molding material. [Diagram 3] FIG. 2 is an enlarged right perspective view of an exemplary embodiment of a molding apparatus of the present disclosure showing a first die and a second die in an open position and a restraint device disposed in a die cavity of the first die. [Figure 4] 1A and 2A-2B. FIG. 2B is a perspective front view of a hat-style stringer that can be formed by the exemplary embodiment of the forming apparatus of FIGS. [Figure 5A] FIG. 2 is a schematic front view illustrating an exemplary embodiment of a molding apparatus of the present disclosure having a restraining assembly in the form of a foam vacuum assembly. [Figure 5B] FIG. 5B is a schematic enlarged front view of the foaming vacuum assembly of FIG. 5A. [Figure 5C] FIG. 5C is a schematic enlarged side view of the foaming vacuum assembly of FIG. 5B. [Figure 6A] FIG. 2 is a schematic front view illustrating an exemplary embodiment of a molding apparatus of the present disclosure having a restraint assembly in the form of a pneumatic assembly. [Figure 6B]FIG. 6B is a schematic enlarged front view of the pneumatic assembly of FIG. 6A. [Figure 6C] FIG. 6C is a schematic enlarged side view of the pneumatic assembly of FIG. 6B. [Figure 6D] 1 is a schematic front view of an exemplary embodiment of a molding apparatus of the present disclosure having a restraint assembly in the form of an alternative pneumatic assembly; [Figure 6E] 1 is a schematic front view of an exemplary embodiment of a molding apparatus of the present disclosure having a restraint assembly in the form of yet another pneumatic assembly; [Figure 7A] 1 is a schematic front view illustrating an exemplary embodiment of a molding apparatus of the present disclosure having a restraint assembly in the form of a spring assembly; [Figure 7B] FIG. 7B is a schematic enlarged front view of the spring assembly of FIG. 7A. [Figure 7C] FIG. 7C is a schematic enlarged side view of the spring assembly of FIG. 7B. [Figure 8] FIG. 1 is a schematic front view of an exemplary embodiment of a molding apparatus of the present disclosure having a restraining assembly in the form of a foam vacuum assembly, illustrating the various forces applied during the molding process. [Figure 9A] FIG. 1 is a flow diagram illustrating an exemplary embodiment of a method of the present disclosure. [Figure 9B] FIG. 11 is a flow diagram illustrating another exemplary embodiment of the method of the present disclosure. [Figure 10A] FIG. 1 is a schematic diagram showing a pre-molding step, illustrating an exemplary embodiment of a molding apparatus of the present disclosure having a restraint assembly viewed from the front, with first and second dies in an open position, and a flat composite molding blank disposed on the first die. [Figure 10B] FIG. 10B is a schematic side view showing the molding apparatus of FIG. 10A in a pre-molding step. [Figure 11A] FIG. 2 is a schematic diagram showing the first molding step of the molding cycle, showing a front view of the molding apparatus and restraint assembly, the first and second dies in the closed position, and the integration of the cap portion of the composite molding blank. [Figure 11B]FIG. 11B is a schematic side view showing the molding apparatus of FIG. 11A in a first molding step. [Figure 12A] FIG. 2 is a schematic elevational view of a second molding step of the molding cycle showing the molding apparatus and restraint assembly from a front view and the second die partially inserted into the die cavity. [Figure 12B] FIG. 12B is a schematic side view showing the molding apparatus of FIG. 12A in a second molding step. [Figure 13A] FIG. 2 is a schematic diagram illustrating the third molding step of the molding cycle, showing the molding apparatus and restraint assembly from a front view and the second die fully inserted into the die cavity. [Figure 13B] FIG. 13B is a schematic side view showing the molding apparatus of FIG. 13A in a third molding step. [Figure 14A] FIG. 1 is a schematic diagram of the post-molding vacuum application step, showing the molding apparatus and restraint assembly from the front, the second die retracted after applying vacuum, and the first and second dies in the open position during the post-molding vacuum application step. [Figure 14B] FIG. 14B is a schematic side view of the molding apparatus of FIG. 14A during a post-molding vacuum application step. [Figure 15A] FIG. 2 is a schematic diagram of the formed stringer removal step showing the forming apparatus and restraint assembly from a front view and showing the formed stringer removed. [Figure 15B] 15B is a schematic side view of the forming apparatus of FIG. 15A during a forming stringer removal step. [Figure 16A] FIG. 13 is a schematic diagram illustrating the vacuum release step, showing the molding apparatus and restraint assembly from a front view and showing the vacuum being released. [Figure 16B] FIG. 16B is a schematic side view of the molding apparatus of FIG. 16A during a vacuum release step. [Figure 17A] FIG. 13 is a schematic diagram showing the first die return step, showing the molding apparatus and restraint assembly from a front view and the first die returned to its original position. [Figure 17B]FIG. 17B is a schematic side view showing the molding apparatus of FIG. 17A in a first die return step. [Figure 18] 1 is a front perspective view of an exemplary embodiment of a secondary retention tool; [Figure 19] FIG. 1 is a perspective view of an aircraft incorporating a highly contoured composite structure produced using an exemplary embodiment of the molding apparatus and process of the present disclosure; [Figure 20] FIG. 1 is a flow diagram illustrating an exemplary aircraft production and service method. [Figure 21] FIG. 1 is an exemplary block diagram of an aircraft.

[0020] The figures presented in this disclosure illustrate various aspects of the disclosed embodiments and only the differences will be described in detail. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] DETAILED DESCRIPTION OF THE DRAWINGS The embodiments of the present disclosure are described in more detail below with reference to the accompanying drawings, in which some, but not all, of the embodiments of the present disclosure are shown. Indeed, several different embodiments are presented, and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are presented so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0022] The present specification includes the phrases "in one embodiment" or "embodiment." Instances of the phrases "in one embodiment" or "in an embodiment" do not necessarily refer to the same embodiment. Particular features, structures, or characteristics may be combined in any suitable manner consistent with the present disclosure.

[0023] As used herein, "comprising" is an open-ended term and when used in the claims, it does not exclude additional structures or steps.

[0024] As used herein, "designed" or "configured" means that various parts or components may be described or claimed as being "designed" or "configured" to perform one or more tasks. In this context, "designed" or "configured" is used to refer to structure and indicates that a part or component includes structure that performs one or more tasks during operation. Thus, a part or component may be said to be configured to perform a task even if the particular part or component is not currently operating (e.g., not powered on).

[0025] As used herein, the terms "first," "second," etc. are used as markers for the noun that follows them and do not imply ordering (e.g., spatial, temporal, or logical ordering).

[0026] In this specification the word "a" or "an" preceding an element or step does not necessarily exclude a plurality of elements or steps.

[0027] Referring now to the drawings, FIG. 1A is a functional block diagram illustrating an exemplary embodiment of a molding apparatus 10 of the present disclosure that is used in a molding process 12 to constrain a composite formed material 14 and shape the composite formed material 14 into a contoured composite structure 16, such as a highly contoured composite structure 18. The blocks illustrated in FIG. 1A depict elements, and the lines connecting the various blocks do not depict any particular dependencies of the elements. Additionally, the connecting lines shown in the various figures contained herein depict example functional relationships and / or physical connections between the various elements, although other alternative or additional functional relationships and physical connections may exist in embodiments of the present disclosure.

[0028] As shown in FIG. 1A, the forming apparatus 10 may be in the form of a highly contoured stringer forming (HCSF) apparatus 10a or other suitable forming apparatus. Preferably, the forming apparatus 10 is an automated forming apparatus 10b (see FIG. 1A), and the forming process 12 is preferably an automated forming process 12a (see FIG. 1A). An example of a forming apparatus 10, such as a highly contoured stringer forming (HCSF) apparatus 10a, used in the forming process 12 to form a contoured composite structure 16, such as a highly contoured composite structure 18, is disclosed in U.S. Pat. No. 8,557,165, the contents of which are incorporated herein by reference in their entirety. However, other types of forming apparatuses may be used to form the highly contoured composite structure 18 in the forming process 12.

[0029] The composite blank 14 is constrained using a molding apparatus 10 and a molding process 12 and formed into a contoured composite structure 16, such as a highly contoured composite structure 18, preferably in the form of an uncured, flat composite blank 14a (see FIG. 1A) or a substantially flat composite blank. The composite blank 14 can be formed by pressure into a contoured composite structure 16 having a desired shape, such as a highly contoured composite structure 18. The composite blank 14 may or may not be heated during this forming process.

[0030] As shown in FIG. 1A, the composite molding feedstock 14 may include a composite laminate molding feedstock 14b, a composite stringer molding feedstock 14c, a dry composite molding feedstock 14d, or other suitable composite molding feedstock. As further shown in FIG. 1A, the composite molding feedstock 14 preferably includes a plurality of plies 20 of a composite material 22, such as a prepreg material 24. The composite material may be a knitted or woven fabric, such as a carbon fiber epoxy prepreg material, pre-impregnated with a resin material 26, such as a resin binder. The composite material 22 may include a carbon fiber reinforced polymer (CFRP) material, including plastic or thermoplastic materials known in the art of composite part manufacturing. The plurality of plies 20 may include unidirectional or bidirectional fiber reinforced materials, i.e., prepregs, impregnated and held together with a suitable resin matrix, such as a thermoset or thermoplastic. The dry composite molding feedstock 14d may be formed of fabric pre-treated with the resin material 26, or may be formed of dry fabric plies bonded together with a tackifier into a desired shape and / or arrangement prior to infusion with the resin. A contoured composite structure 16, such as the highly contoured composite structure 18, is typically formed into a desired shape while the composite material 22 of the composite molding feedstock 14 is in a green or uncured state and then cured while supported in the desired shape.

[0031] The contoured composite structure 16, such as the highly contoured composite structure 18, formed from the composite molding feedstock 14 using the molding apparatus 10 and molding process 12 of the present disclosure is preferably an elongated contoured composite structural member 28 (see FIG. 1A), such as an elongated contoured composite part 28a (see FIG. 1A). Such elongated contoured composite structural members may be used in a variety of industries and applications, including, but not limited to, the manufacture of aircraft 400a (see FIG. 19), as well as other aerospace structures and vehicles.

[0032] A contoured composite structure 16, such as the highly contoured composite structure 18, has one or more contours 30, such as one or more complex contours 30a (see FIGS. 1A and 4), along its length 32 (see FIG. 1A). A contoured composite structure 16, such as the highly contoured composite structure 18 of the present disclosure, can have a variety of contours 30, such as the complex contour 30a, and can have shapes including curves, angles, flanges, complex contours, highly contoured contours, and the like.

[0033] As shown in FIG. 1A , a contoured composite structure 16, such as highly contoured composite structure 18, may include one or more of stringers 34, such as hat stringer 34a, aircraft stringer 34b, hat aircraft stringer 34c, fuselage stringer 34d, keel stringer 34e, wing stringer 34f, stabilizer stringer 34g, or other suitable stringers, may include stiffening members 36, such as hat stiffening member 36a or other suitable stiffening members, may include wing spars 38, or may include other suitable highly contoured composite structures.

[0034] A stringer 34, such as hat-shaped stringer 34a described below with reference to Figure 4, has a cross-sectional shape 40 (see Figure 4) that includes a hat shape 42 (see Figure 4). A stringer 34, such as hat-shaped stringer 34a, preferably includes a contoured hat portion 43 (see Figures 1A and 4) having a cap 52 (see Figures 1A and 4). The cap 52 of a highly contoured composite structure 18 formed in the molding process 12, such as a contoured composite structure 16, such as hat-shaped stringer 34a, preferably has a contour radius 98 (see Figure 1A) in the range of 500 inches to 1000 inches, and more preferably has a contour radius 98 in the range of 500 inches to 750 inches.

[0035] As used herein, "contoured composite structure" and "highly contoured composite structure" refer to various complex and highly contoured composite structures and parts that, due to the relative steepness or slope of the contour, such as the complex contour, may result in wrinkles or lumps between the multiple plies that form the composite molded material when using known molding techniques or processes.

[0036] As used herein, "contoured" or "highly contoured" means a constant or variable contour, such as a complex contour or curvature, along the length of a composite material having such relative steepness or slope that wrinkles or lumps may occur between the plies that make up the composite material when using known molding techniques or processes.

[0037] As used herein, "wrinkle" refers to a stressed area that is locally formed in a composite material during the molding process, such as fiber distortion, ply distortion, or artifacts that may form in the composite material, and / or a stressed area that is created in a shaped contoured composite structure or part during manufacturing or molding due to buckling, excess fiber material moving out of plane, or deformation that occurs between plies when one or more areas, such as a contoured area, in the composite material are pressed or compressed during manufacturing or molding.

[0038] The molding apparatus 10 and molding process 12 of the present disclosure are designed to provide wrinkle prevention 44 (see FIG. 1A) or wrinkle reduction 45 (see FIG. 1A), i.e., to prevent, eliminate, or substantially reduce or minimize the formation of wrinkles and fiber distortions in the cap portion 50a of the composite molding feedstock 14 and thus in the cap 52 of the contoured composite structure 16, such as the highly contoured composite structure 18, that is formed. Thus, the cap 52 of the contoured composite structure 16, such as the highly contoured composite structure 18, that is formed using the molding apparatus 10 and molding process 12 of the present disclosure is preferably wrinkle-free 46 (see FIG. 1A) or wrinkle-reduced 48 (see FIG. 1A).

[0039] As shown in FIG. 1A, in an exemplary embodiment, a molding apparatus 10, such as a highly contoured stringer forming (HCSF) apparatus 10a, includes a first die 54, also referred to as a female die 54a, a lower die 54b, or a lower pallet 54c. The first die 54, such as a female die 54a, a lower die 54b, or a lower pallet 54c, includes a plurality of pairs 55 (see FIG. 2B) of first die portions 56 (see FIGS. 1A and 2B). The first die portions 56 of the plurality of pairs 55 are spaced apart from one another to define a die cavity 58 (see FIGS. 1A and 2B) in which the cap portion 50a of the composite molding blank 14 is molded into the contoured hat portion 43 with the cap 52. The first die portions 56 of the plurality of pairs 55 are slidably displaceable relative to one another. The multiple pairs 55 (see FIG. 2B) can include a first element 55a (see FIG. 2B) of each pair 55 and a second element 55b (see FIG. 2B) of each pair 55. The first die part 56 can be in the form of a die block 56a (see FIGS. 2B and 3) or can have any other suitable shape.

[0040] As shown in FIG. 1A, a molding apparatus 10, such as the highly contoured stringer molding apparatus 10a, further includes a restraint assembly 60 connected to the first die 54. The restraint assembly 60 includes a restraint device 62 (see FIGS. 1A and 1B) disposed at or within the die cavity 58 of the first die 54. As described in more detail below, the restraint assembly 60, and in particular the restraint device 62 of the restraint assembly 60, is designed to restrain the cap portion 50a of the composite molding feedstock 14 before and during the molding process 12 to secure the composite molding feedstock 14, and in particular the cap portion 50a of the composite molding feedstock 14, thereby relieving stresses from the cap portion 50a and the cap 52 to provide wrinkle prevention 44, i.e., to prevent wrinkles and fiber distortions from forming, in the cap portion 50a of the composite molding feedstock 14 and the cap 52 formed from the cap portion 50a. Thus, the restraining device 62 of the restraining assembly 60 provides a stress transfer 49 (see FIG. 1A ) that transfers stress, such as that caused by pressing, from the cap portion 50a and the cap 52 during the molding process 12. As will be described in detail below, the restraining assembly 60, and in particular the restraining device 62, applies an upward resistance force 92 (see FIGS. 1A and 1B ) to the composite molding material 14, such as the cap portion 50a, or the cap 52, and to a downward pressing force 90 (see FIG. 1A ) applied by the second die 64. The upward resistance force 92 of the restraining device 62 and the downward pressing force 90 of the second die 64 act to clamp or restrain the cap portion 50a of the composite molding material 14, or the cap 52 formed by the cap portion 50a, to transfer stress from the cap portion 50a or the cap 52 and to prevent 44 (see FIG. 1A ) or reduce 45 (see FIG. 1A ) wrinkles in the cap portion 50a or the cap 52.

[0041] As shown in FIG. 1A, the molding apparatus 10, such as the highly contoured stringer molding apparatus 10a, further includes a second die 64, also referred to as a male die 64a or an upper die 64b. The second die 64, such as the male die 64a or the upper die 64b, has a plurality of pairs 65 (see FIGS. 2B and 3) of second die portions 66 (see FIGS. 1A, 2B, and 3). The plurality of pairs 65 of second die portions 66 are independently displaceable relative to one another. As shown in FIG. 1A, the second die 64 has a tapered portion 68, such as in the form of a punch 68a, designed to be inserted at least partially into the die cavity 58 during the molding process 12. The composite molding blank 14 is molded between the first die 54 and the second die 64, and the restraining device 62 of the restraining assembly 60 is designed to restrain the cap portion 50a of the composite molding blank 14 between the restraining device 62 and the second die 64 before and during the molding process 12.

[0042] As shown in FIG. 1A, a forming apparatus 10, such as the highly contoured stringer forming apparatus 10a, further includes a control system 70 that operatively controls the operation 72 of the forming apparatus 10, including controlling the movement of the first die 54 and the second die 64 in coordination with the movement of the constraint assembly 60. As shown in FIG. 1A, the control system 70 includes a controller 74. The controller 74 may include one or more computers 76, such as a portable computer (PC) (see FIG. 1A), or a programmable logic controller (PLC), that control the operation 72 of a plurality of contour control actuators 78 (see FIG. 2A) and a plurality of forming actuators 80 (see FIG. 2A) of the forming apparatus 10. In one embodiment, the controller 74 uses a control program 82 (see FIG. 1A). The control program may include a software program or algorithm that determines how forming should proceed and determines the sequential operation of the plurality of forming actuators 80. A set of operator input controls 84 (see FIG. 1A) allows an operator to input or modify the control program 82, contour data 85 (see FIG. 1A) for a contoured composite structure 16, such as a highly contoured composite structure 18, to be molded, or other suitable data sets at operator specified values. The controller 74 may also receive signals from a load cell 86 (see FIG. 1A) that is used to monitor pressure 88 (see FIG. 1A) applied to the composite molding feedstock 14 by a plurality of contour control actuators 78 and a plurality of molding actuators 80.

[0043] 1B, a functional block diagram illustrating an exemplary embodiment of a restraint assembly 60 that can be used in the molding apparatus 10 and molding process 12 shown in FIG. 1A is shown. The blocks illustrated in FIG. 1B depict elements, and the lines connecting the various blocks do not depict any particular dependencies of the elements. Additionally, the connecting lines shown in the various figures contained herein depict example functional relationships and / or physical connections between the various elements, although other alternative or additional functional relationships and physical connections may exist in embodiments of the present disclosure.

[0044] Prior to and during molding process 12, a restraint assembly 60 (see FIGS. 1A and 1B), and in particular a restraint device 62 (see FIGS. 1A and 1B), restrains a portion 50 (see FIG. 1A) of the composite molding material 14 (see FIG. 1A), such as a cap portion 50a (see FIG. 1A) of the composite molding material 14, between the restraint device 62 and a second die 64 (see FIG. 1A), such as a tapered portion 68 (see FIG. 1A) of the second die 64.

[0045] As the second die 64 exerts a downward pressing force 90 (see FIG. 1A ) against the portion 50, such as cap portion 50a, forcing the portion 50, such as cap portion 50a, downwardly pressing the restraining device 62 and displacing one or more pairs 55 (FIGS. 2B and 3) of the first die portions 56 (see FIGS. 1A , 2B and 3 ) laterally outwardly apart, the restraining assembly 60, and in particular the restraining device 62, is designed to exert an upward resisting force 92 (see FIGS. 1A and 1B ) against the first surface 51 a (see FIG. 5A ) of the cap portion 50a and against the downward pressing force 90, which exerts an upward resisting force 92 to prevent wrinkles 44, i.e., to prevent wrinkles and fiber distortions from forming in the portion 50, such as cap portion 50a, and in the cap 52, as the contoured hat portion 43 is formed from the composite molding material 14.

[0046] 1B, 5B, 6B, 6D, 6E, and 7A, the restraining device 62 has a first end 94a, a second end 94b, and a body 95 disposed between the first end 94a and the second end 94b. The first end 94a of the restraining device 62 is designed to directly or indirectly engage or contact a first surface 51a of a cap portion 50a of a composite molding material 14, such as a flat composite molding material 14a, e.g., a composite laminate molding material 14b, to apply an upward resistance force 92 against the first surface 51a of the cap portion 50a and against a downward pressure force 90 applied by the second die 64, thereby clamping the cap portion 50a between the tapered portion 68 of the second die 64 during and prior to forming the composite molding material 14 into the highly contoured composite structure 18 in the molding process 12. Further, during forming process 12 forming composite blank 14 into highly contoured composite structure 18, restraining device 62 is initially in extended position 112 (see FIGS. 1B, 5A, 6A, 6D, 6E, and 7A) in die cavity 58 to restrain cap portion 50a against second die 64. When tapered portion 68 of second die 64 is fully inserted into die cavity 58, restraining device 62 is positioned in pressing position 116 (see FIGS. 1B and 13B) and one or more pairs 55 of first die portions 56 are positioned laterally outward from restraining device 62.

[0047] In one embodiment, the restraining device 62 is a single-use restraining device 62a (see FIG. 1B) that is designed to be used a single time, i.e., one time, for a molding process 12 or molding cycle, and then removed from the first die 54 of the molding apparatus 10. In another embodiment, the restraining device 62 is a multiple-use restraining device 62b (see FIG. 1B) that is designed to be used more than once, i.e., multiple times, for more than one molding process 12 or molding cycle.

[0048] 1B, the restraining assembly 60 further includes a retaining element 96 that is designed to and does retain the restraining device 62 in a pressing position 116 (see FIG. 1B) after, for example, the molding process 12 has formed a contoured composite structure 16, such as the highly contoured composite structure 18, and after, for example, the second die 64 has retracted from the contoured composite structure 16, such as the highly contoured composite structure 18, and from the first die 54, to prevent the contoured composite structure 16, such as the highly contoured composite structure 18, from being undesirably pushed up by the restraining device 62. Thus, when the second die 64, i.e., male die 64a, retracts from the first die 54, i.e., female die 54a after the molding process 12, the retaining element 96 holds the restraining device 62 in the pressing position 116 so that the contoured composite structure 16, such as the highly contoured composite structure 18, is maintained in a predetermined position on the first die 54, i.e., female die 54a and does not undesirably move upwardly before the contoured composite structure 16, such as the highly contoured composite structure 18, is removed from the first die 54, i.e., female die 54a.

[0049] Prior to the molding process 12 to form a contoured composite structure 16, such as the highly contoured composite structure 18, from the composite molding feedstock 14, the restraining device 62 is preferably in an extended position 112 (see FIG. 1B), such as a fully extended position. During the molding process 12 to form a contoured composite structure 16, such as the highly contoured composite structure 18, from the composite molding feedstock 14, the restraining device 62 may be pressed to one or more intermediate press positions 114 (see FIG. 1B). Upon completion of the molding process 12 to form a contoured composite structure 16, such as the highly contoured composite structure 18, the restraining device 62 is preferably lowered or pressed to a press position 116 (see FIG. 1B), such as a fully pressed position.

[0050] 1B and described below with reference to Figures 5A-5C, in one embodiment, restraint assembly 60 includes foam vacuum assembly 100 and restraint device 62 includes compressible foam element 102. Compressible foam element 102 has a first end 103a (see Figure 5B), a second end 103b (see Figure 5B), and a body 104 (see Figure 5B) disposed between first end 103a and second end 103b.

[0051] 1B and 5A-5B, foam vacuum assembly 100 includes compressible foam element 102, a vacuum bag 105 surrounding compressible foam element 102, a vacuum source 106 coupled to vacuum bag 105 via vacuum line 108, and one or more control valves 110. Foam vacuum assembly 100 may include various components or parts known in the art, as described below.

[0052] The compressible foam element 102 is covered or surrounded by a vacuum bag 105. The vacuum bag 105 can be made of plastic materials including plastic film, such as polyethylene, nylon, or other suitable plastic film materials, or plastic sheeting made of silicone rubber, polyurethane, or other suitable plastic sheeting materials. One or more seals can be used to seal the periphery of the vacuum bag 105 and the periphery of the vacuum line 108, i.e., where the vacuum hose enters the vacuum bag 105. The one or more seals can be formed of a sealing material such as tape or adhesive, e.g., mastic or other suitable sealing material. If desired, the vacuum bag 105 can be used with a release film, peel ply, breather cloth, or other suitable material to separate the vacuum bag 105 and the compressible foam element 102.

[0053] The vacuum bag 105 has a port opening 107 (see FIG. 5B) configured to receive a vacuum line 108 or vacuum hose. The vacuum line 108 or vacuum hose has a first end 109a (see FIG. 5B) and a second end 109b (see FIG. 5B). The first end 109a of the vacuum line 108 or vacuum hose is connected to the port opening 107 of the vacuum bag 105 at or near the second end 103b of the compressible foam element 102. It is noted that the vacuum line 108 may be connected to the vacuum bag 105 at or near other areas of the compressible foam element 102. The second end 109b of the vacuum line 108 is connected to a vacuum source 106 (see FIG. 5B). The vacuum line 108, such as a vacuum hose, may also be used with fittings or components or parts known in the art.

[0054] The vacuum bag 105 is connected to a vacuum source 106 via a vacuum line 108, such as a vacuum hose. The vacuum source 106 (see FIG. 1B, FIG. 5A-5C) may be in the form of a vacuum pump 106a (see FIG. 5A-5C) or other suitable vacuum source. The vacuum source 106, such as the vacuum pump 106a, draws or draws air from the vacuum bag 105 container. As the vacuum source 106, such as the vacuum pump 106a, draws air from within the vacuum bag 105 container, the air pressure within the vacuum bag 105 container is reduced. The vacuum pump 106a may include a mechanical vacuum pump, such as a piston pump, a rotary vane pump, or a turbine pump, or other suitable mechanical vacuum pump. The minimum pumping requirements of the vacuum pump 106a are determined by the size and shape of the compressible foam element 102 being used and the size and shape of the vacuum bag 105 surrounding the compressible foam element 102.

[0055] One or more control valves 110 (see FIG. 1B, 5A-5C) may be used. In one example, one control valve 110 (see FIG. 5B) is used, and is incorporated into the vacuum line 108 to allow an operator to turn the vacuum source 106 on and off and adjust the rate at which air is removed from the vacuum bag 105. In another example, two control valves are used, with one control valve 110 incorporated into the vacuum line 108 to turn the vacuum source 106 on and off and adjust the rate at which air is removed from the vacuum bag 105, and the other control valve 110 incorporated into the vacuum line 108 or the vacuum bag 105 to adjust the vacuum pressure 118 within the vacuum bag 105. The foam vacuum assembly 100 may further include a vacuum gauge or other suitable component to monitor the level of vacuum pressure 118.

[0056] Prior to the molding process 12, the compressible foam element 102 is in an expanded position 112a (see FIG. 1B). During the molding process 12 of a contoured composite structure 16, such as the highly contoured composite structure 18, the compressible foam element 102 is forced downward by the second die 64, and in particular by the tapered portion 68 of the second die 64, to one or more intermediate pressing positions 114a (see FIG. 1B). The compressible foam element 102 exerts an upward resistance force 92 (see FIG. 1B) against the cap portion 50a of the composite molding material 14 and against the downward pressure force 90 (see FIG. 1A) exerted by the second die 64. The compressible foam element 102 holds the cap portion 50a of the composite molding material 14 in place prior to and during the molding process 12. Upon completion of the molding process 12 of a contoured composite structure 16, such as highly contoured composite structure 18, the compressible foam element 102 is preferably compressed to a compressed position 116a (see FIG. 1B), such as a fully compressed position.

[0057] After the molding process 12 is completed, as the second die 64 retracts or moves away from the first die 54, a vacuum pressure 118 (see FIG. 1B) is preferably applied by a vacuum source 106, such as a vacuum pump 106a, to, for example, draw or suck air out of a gap 266 (see FIGS. 5B-5C) between the vacuum bag 105 and the compressible foam element 102. This causes the vacuum bag 105 to compress around the compressible foam element 102, holding it down in a pressed position 116a, such as a fully pressed position.

[0058] Thus, in the foam vacuum assembly 100, the holding element 96 (see FIG. 1B) includes a vacuum bag 105 to which a vacuum pressure 118 is applied to hold or press the compressible foam element 102 in the pressed position 116a after the molding process 12, i.e., molding cycle, and after the second die 64 is retracted, so that the compressible foam element 102 does not re-expand to the expanded position 112a (see FIG. 1B) and thus prevents the contoured composite structure 16, such as the highly contoured composite structure 18, from being forced upwardly out of the die cavity 58 of the first die 54. If a contoured composite structure 16, such as the molded highly contoured composite structure 18, is forced upwardly out of the die cavity 58 of the first die 54, the contoured or curved shape of the molded contoured structure may flatten if the structure remains forced upwardly out of the die cavity 58 of the first die 54 for a short period of time, such as, for example, 5-10 minutes. A vacuum pressure 118 is preferably applied to the vacuum bag 105 and the compressible foam element 102 such that the vacuum bag 105 can act as a retention element 96 to maintain and hold the compressible foam element 102 in the pressed position 116a until the contoured composite structure 16, such as the highly contoured composite structure 18, is removed from the first die 54. Once the contoured composite structure 16, such as the highly contoured composite structure 18, is removed from the first die 54, the vacuum pressure 118 is turned off or released by closing or turning off one or more control valves 110 to the vacuum source 106, thereby allowing the compressible foam element 102 to expand back to the expanded position 112a again.

[0059] 1B, in one embodiment, the compressible foam element 102 is a single use compressible foam element 102a, which is designed to be used a single time, i.e., one time, for a molding process 12 or molding cycle, and then removed from the first die 54 of the molding apparatus 10. In another embodiment, as shown in FIG. 1B, the compressible foam element 102 is a multiple use compressible foam element 102b, which is designed to be used more than once, i.e., multiple times, for more than one molding process 12 or molding cycle. The compressible foam element 102 may be removably mounted in the die cavity 58 of the first die 54 to facilitate removal of the compressible foam element 102 for cleaning or repair, or to facilitate removal of the compressible foam element 102 for replacement with an unused or new compressible foam element.

[0060] As further shown in FIG. 1B, the compressible foam element 102 includes a compressible material 120, such as a compressible foam material 122. As shown in FIG. 1B, the compressible foam material 122 may include an open cell foam 124, such as a polyurethane foam 124a, a latex rubber foam 124b, or other suitable open cell foam. Preferably, the open cell foam 124 has a compressible strength of 3 lb / ft 3 (3 pounds / cubic foot)~13 lb / ft 3 The foam is in the form of a high density foam 126a (see FIG. 1B) having a density 128a (see FIG. 1B) in the range of 13 pounds per cubic foot.

[0061] 1B, the compressible foam material 122 may also include a closed cell foam 130, such as a polyethylene foam 130a, such as an expanded polyethylene foam, a polystyrene foam 130b, such as an expanded polystyrene foam, a polypropylene foam 130c, such as an expanded polypropylene foam, a neoprene foam rubber 130d, or other suitable closed cell foam. Preferably, the closed cell foam 130 has a foam strength of 2 lb / ft 3 (2 pounds / cubic foot)~10 lb / ft3 The foam is in the form of a high density foam 126b (see FIG. 1B) having a density 128b (see FIG. 1B) in the range of 10 (10 pounds per cubic foot).

[0062] The densities 128a, 128b selected for the compressible foam material 122 of the compressible foam element 102 are determined by the type of composite molding feedstock 14 used and the type of contoured composite structure 16, such as the highly contoured composite structure 18, or part being molded using the molding apparatus 10 and molding process 12.

[0063] As shown in FIG. 1B and described below with reference to FIGS. 6A-6C, in another embodiment, the restraint assembly 60 includes a pneumatic assembly 132, and the restraint device 62 includes an air cylinder rod 134 having a cap presser 136. The pneumatic assembly 132 includes an air cylinder rod 134 having a first end 138a (see FIG. 6B), a second end 138b (see FIG. 6B), and a rod body 140 (see FIG. 6B) disposed between the first end 138a and the second end 138b. The air cylinder rod 134 may be in the form of a piston rod 134a (see FIG. 1B) movable in an up-down direction 142 (see FIG. 6B) and designed to move back and forth from an extended position 112b (see FIG. 1B) to one or more intermediate pressed positions 114b (see FIG. 1B) to a pressed position 116b (see FIG. 1B). The piston rod 134a is attached to a piston head 135 (see FIGS. 1B and 6B). The air cylinder rod 134 may be constructed of a metallic material such as steel, aluminum, or other suitable metallic material. A first end 138a of the air cylinder rod 134 is coupled to a cap presser 136. The cap presser 136 is preferably a semi-rigid cap presser 136a (see FIGS. 1B and 6B) having an engagement surface 144 (see FIG. 6B) configured to engage a portion 50 of the composite molding blank 14 (see FIG. 6A), e.g., a first surface 51a (see FIG. 6A) of a cap portion 50a (see FIG. 6A), and to engage a cap 52 (see FIG. 1A) formed from the cap portion 50a. The cap presser 136, such as the semi-rigid cap presser 136a, is preferably in the form of a bar formed of aluminum, other suitable metallic material, or other suitable semi-rigid material. The cap presser 136, such as semi-rigid cap presser 136a, in the form of an aluminum bar, has a thickness of, for example, 0.125 inches, or other suitable thickness.

[0064] Preferably, the air cylinder rod 134 with the cap presser 136 includes a multiple use restraining device 62b (see FIG. 1B) that allows for multiple use for multiple molding processes 12, i.e., molding cycles. The air cylinder rod 134 with the cap presser 136 may be removably attached to the die cavity 58 of the first die 54 to allow the air cylinder rod 134 with the cap presser 136 to be removed for cleaning or repair, or to allow the air cylinder rod 134 with the cap presser 136 to be removed and replaced with an unused or new air cylinder rod and / or cap presser.

[0065] The pneumatic assembly 132 further includes an air cylinder 146 (see FIGS. 1B and 6B) coupled to the air cylinder rod 134. The air cylinder 146 includes a first end 148a (see FIG. 6C), a second end 148b (see FIG. 6C), and a cylinder tube 150 (see FIG. 6C) disposed between the first end 148a and the second end 148b. The first end 148a of the air cylinder 146 has an opening 152 (see FIG. 6B) that is configured to receive the second end 138b and rod body 140 of the air cylinder rod 134 when the air cylinder rod 134 is depressed or moved downward from the extended position 112b (see FIG. 1B) to one or more intermediate depressed positions 114b (see FIG. 1B) to a depressed position 116b (see FIG. 1B), such as a fully depressed position. The air cylinder 146, such as a pneumatic air cylinder, is a linear actuator that operates using compressed air 160 (see FIG. 1B).

[0066] The pneumatic assembly 132 further includes one or more air supply lines 154 (see FIGS. 1B and 6B). Each air supply line 154 has a first end 156a (see FIG. 6B) coupled to an air cylinder 146 and a second end 156b (see FIG. 6B). The second end 148b of the air cylinder 146 has a port 157 (see FIG. 6B), such as a first port 157a (see FIG. 6B), that is configured to receive an air supply line 154 (see FIGS. 1B and 6B), such as a first air supply line 154a (see FIG. 6B). In another embodiment, the air cylinder 146 (see FIG. 6D) has a second port 157b (see FIG. 6D), that is configured to receive another air supply line 154 (see FIG. 6D), such as a second air supply line 154b (see FIG. 6D). The pneumatic assembly 132 further includes an air source 158 (see FIGS. 1B and 6B) coupled to the second end 156b of each air supply line 154. The air source 158 preferably includes compressed air 160 (see FIG. 1B), which may be stored, for example, in a tank or a pump, and is provided to the air cylinder 146 and applied as air pressure 162 (see FIG. 1B) to the air cylinder 146 and against the air cylinder rod 134. The pneumatic assembly 132 further includes one or more pressure control valves 164 (see FIG. 6B), which are coupled to the one or more air supply lines 154 and turn on and off the air pressure 162 from the air source 158 and regulate the rate at which the air pressure 162 is applied. The pneumatic assembly 132 may further include gaskets or seals or other components or parts known in the art of pneumatic cylinders.

[0067] In one embodiment, the air cylinder 146 (see FIGS. 1B and 6B) is a single-acting spring-return air cylinder 146a (see FIGS. 1B and 6B) having one air supply line 154 (see FIGS. 1B and 6B), such as a first air supply line 154a (see FIG. 6B), connected between an air supply source 158 and a first port 157a of the single-acting spring-return air cylinder 146a. The single-acting spring-return air cylinder 146a includes a spring 166 (see FIG. 6B), such as a mating spring, disposed within the cylinder tube 150 of the air cylinder 146 and mated around the rod body 140 of the air cylinder rod 134 between an interior first end 148a (see FIG. 6B) of the air cylinder 146 and the piston head 135.

[0068] When the single acting spring-return air cylinder 146a is pressurized by compressed air 160 from an air supply 158 and air pressure 162 (see FIG. 1B) is applied to the single acting spring-return air cylinder 146a, the air cylinder rod 134, such as the piston rod 134a having the cap presser 136, extends or moves vertically upward from a pressing position 116b (see FIG. 1B), i.e., a base or lower position, to an extended or upper position 112b (see FIG. 1B) to counteract the downward pressing force 90 of the second die 64, i.e., the male die 64a or the upper die 64b. During the process of forming the composite molding blank 14 into the highly contoured composite structure 18, a restraining device 62, such as an air cylinder rod 134 (see FIG. 6A) having a cap presser 136 (see FIG. 6A), is initially in an extended position 112 (see FIG. 6A), such as extended position 112b (see FIG. 6A), within or partially within the die cavity 58 to restrain the cap portion 50a (see FIG. 6A) against the second die 64 (see FIG. 6A). Upon the compressed air 160 from the air supply 158 being stopped or turned off, the air cylinder rod 134, such as piston rod 134a, retracts due to a spring force 170 (see FIG. 1B). The single acting spring return air cylinder 146a operates using compressed air 160 to actuate the air cylinder rod 134, i.e., piston rod 134a, in one direction and also operates using a spring force 170 to return the air cylinder rod 134, i.e., piston rod 134a, to the depressed position 116b, i.e., base or lower position. The cylinder tube 150 of the air cylinder 146 has one port 157, i.e., first port 157a, that is used to supply and exhaust the compressed air 160. The air cylinder rod 134, i.e., piston rod 134a, is preferably returned to the depressed position 116b, i.e., base or lower position, by a spring 166 (see FIGS. 1B and 6B). However, in other embodiments, the air cylinder rod 134, i.e., piston rod 134a, may be returned to the depressed position 116b, i.e., base or lower position, by external means such as gravity, weight, mechanical motion, or an external spring.

[0069] Upon completion of molding process 12, i.e., molding cycle, air pressure 162 is turned off by pressure control valve 164 and air cylinder rod 134, such as piston rod 134a, of single acting spring return air cylinder 146a, moves vertically downward to pressing position 116b, i.e., base or lower position, where it remains. Just prior to the start of molding process 12, i.e., the next molding cycle, air pressure 162 is activated by pressure control valve 164 and air cylinder rod 134, such as piston rod 134a, with cap presser 136, moves vertically upward from pressing position 116b, i.e., base or lower position, to extended position 112b, i.e., upper position. When using a single-acting spring-return air cylinder 146a, the retaining element 96 (see FIG. 1B) of the restraining assembly 60, which functions to hold or maintain the air cylinder rod 134, such as the piston rod 134a, downward, after the completion of the molding process 12, exerts a spring return 168 and a spring force 170 as a result of the absence of air pressure 162a (see FIG. 1B), in which the air pressure 162 is stopped by the pressure control valve 164 and no air pressure 162 is applied to the air cylinder rod 134, such as the piston rod 134a. In this manner, due to the retaining element 96 exerting the spring return 168 and the spring force 170 as a result of the absence of air pressure 162a, the air cylinder rod 134, such as the piston rod 134a, remains in the pressing position 116b, i.e., the base position or the lower position, when the second die 64, i.e., the male die 64a or the upper die 64b, retracts after the completion of the molding process 12, i.e., the molding cycle. Additionally, the retaining element 96 relieves the upward resistive force 92 (see FIG. 1B) exerted by the restraining device 62 when the second die 64, i.e., the upper die 64b, retracts upward.

[0070] In another embodiment, the air cylinder 146 (see FIGS. 1B and 6D) is a double-acting air cylinder 146b (see FIGS. 1B and 6D) that has two air supply lines 154 (see FIGS. 1B and 6D), such as a first air supply line 154a (see FIG. 6D) and a second air supply line 154b (see FIG. 6D), connected between an air supply source 158 and the double-acting air cylinder. Each of the two air supply lines 154 has a pressure control valve 164 coupled thereto. For example, the first air supply line 154a is connected to the double-acting air cylinder 146b together with a first pressure control valve 164a (see FIG. 6B) that operates the first air supply line 154a to turn on / off the air pressure 162 from the air supply source 158, and the second air supply line 154b is connected to the double-acting air cylinder 146b together with a second pressure control valve 164b (see FIG. 6B) that operates the second air supply line 154b to turn on / off the air pressure 162 from the air supply source 158. The first air supply line 154a is coupled to a lower hole 172 (see FIG. 6D) provided in the cylinder tube 150 of the double-acting air cylinder 146b via a first port 157a (see FIG. 6D). The second air supply line 154b is coupled through a second port 157b (see FIG. 6D) to an upper bore 174 (see FIG. 6D) provided in the cylinder tube 150 of the double-acting air cylinder 146b.

[0071] When the double-acting pneumatic cylinder 146b is used, compressed air 160 is supplied and air pressure 162 is applied to the lower hole 172 of the double-acting pneumatic cylinder 146b via the first air supply line 154a, causing the pneumatic cylinder rod 134, i.e., piston rod 134a, to move vertically upward from the pressed position 116b, i.e., lower or base position, to the extended position 112b, i.e., extended or upper position. During the process of forming the composite molding blank 14 into the highly contoured composite structure 18, a restraining device 62 (see FIG. 6D), such as an air cylinder rod 134 (see FIG. 6D) having a cap presser 136 (see FIG. 6D), is in an extended position 112 (see FIG. 6D), such as extended position 112b (see FIG. 6D), within or partially within the die cavity 58 (see FIG. 6D) to restrain the cap portion 50a (see FIG. 6D) against the second die 64 (see FIG. 6D) and react against the downward pressing force 90 of the second die 64, i.e., the male die 64a or the upper die 64b. When the molding process 12, i.e., molding cycle, is completed, the air pressure 162 is removed from the lower hole 172 by deactivating the air pressure 162 in the first air supply line 154a using the first pressure control valve 164a, and the air pressure 162 is applied, e.g., air pressure application 162b (see FIG. 1B), to the upper hole 174 by activating the air pressure 162 in the second air supply line 154b using the second pressure control valve 164b. The air pressure 162 applied to the upper hole 174 pushes down the air cylinder rod 134, maintaining or holding the air cylinder rod 134 in the pressed position 116b, i.e., base or lower position, within the cylinder tube 150 of the double acting air cylinder 146b.

[0072] When using a double-acting air cylinder 146b, the retaining element 96 (see FIG. 1B) of the restraining assembly 60, which functions to hold or maintain the air cylinder rod 134, such as the piston rod 134a with the cap presser 136, downward after the molding process 12 is completed, applies air pressure 162b (see FIG. 1B) to the upper hole 174 of the double-acting air cylinder 146b. The application of air pressure 162b to the upper hole 174 can press down the air cylinder rod 134, such as the piston rod 134a with the cap presser 136, to maintain or hold the air cylinder rod in the pressed position 116b, i.e., the base or lower position. In this manner, when the holding element 96 applies air pressure 162b to the air cylinder rod 134 through the upper hole 174 and presses down on the air cylinder rod 134, the air cylinder rod 134, such as the piston rod 134a having the cap presser 136, can remain in the pressing position 116b, i.e., the base position or the lower position, for example, when the second die 64, i.e., the male die 64a or the upper die 64b, retracts after the molding process 12 is completed.

[0073] The double-acting air cylinder 146b generates thrust, i.e., output, in both the extension and retraction directions. The cylinder tube 150 of the double-acting air cylinder 146b has a first port 157a (see FIG. 6D) and a second port 157b (see FIG. 6D) at both ends. In other words, the first port 157a is located at the second end 148b (see FIG. 6D), and the second port 157b is located at the first end 148a (see FIG. 6D). An air cylinder rod 134, such as the piston rod 134a, is moved vertically upwards and downwards by alternately switching the port 157, which receives compressed air 160 applied at high pressure, to either the first port 157a or the second port 157b. Air pressure 162 is alternately applied to the ends, such as the first end 138a and the second end 138b, of the air cylinder rod 134, which are located opposite each other. Pneumatic application 162b of compressed air 160 generates a thrust on a positive (push) stroke and a thrust on a negative (pull) stroke.

[0074] In yet another embodiment, the air cylinder 146 (see FIGS. 1B and 6E) is a rod-locking air cylinder 146c (see FIGS. 1B and 6E). The rod-locking air cylinder 146c includes an actuating rod locking device 176 (see FIGS. 1B and 6E) disposed within the cylinder tube 150 of the air cylinder 146 or outside the first end 148a of the air cylinder 146. The actuating rod locking device 176 is configured to couple to the air cylinder rod 134 to secure or hold the air cylinder rod 134 in the pressed position 116b.

[0075] The actuating rod lock device 176 includes an actuator 178 (see FIGS. 1B and 6E) configured to actuate a rod lock 180 (see FIGS. 1B and 6E) to couple and secure or press firmly against one or more portions of the air cylinder rod 134 to secure or hold the air cylinder rod 134 in the pressed position 116b. The actuator 178 is actuated by an actuating force mechanism 182 (see FIG. 1B), such as a spring, compressed air pressure, or other suitable actuating force mechanism. The rod lock 180 may include a clamp, spring pin, lever, or other suitable locking element that is released by the actuator 178 to secure or hold the air cylinder rod 134 in the pressed position 116b. In one embodiment, the actuation rod locking device 176 may be in the form of a cartridge assembly disposed transversely relative to the air cylinder rod 134, such as piston rod 134a, and the actuation rod locking device 176 is preferably automatic for locking and unlocking the air cylinder rod 134, such as piston rod 134a. When it is desired to unlock the air cylinder rod 134, such as piston rod 134a, and move it to the extended position 112b, the actuation rod locking device 176 is unlocked to release the rod lock 180 from holding the air cylinder rod 134, such as piston rod 134a.

[0076] When using the rod lock air cylinder 146c, during the process of forming the composite molding blank 14 into the highly contoured composite structure 18, a restraining device 62 (see FIG. 6E), such as an air cylinder rod 134 (see FIG. 6E) having a cap presser 136 (see FIG. 6E), is in an extended position 112 (see FIG. 6E), such as an extended position 112b (see FIG. 6E), within or partially within the die cavity 58 (see FIG. 6E) to restrain the cap portion 50a (see FIG. 6E) against the second die 64 (see FIG. 6E) and react against the downward pressing force 90 of the second die 64, i.e., the male die 64a or the upper die 64b. When using the rod lock air cylinder 146c, the retaining element 96 (see FIG. 1B) of the restraining assembly 60, which functions to hold or maintain the air cylinder rod 134, such as the piston rod 134a with the cap presser 136, in the pressing position 116b (see FIG. 1B), i.e., the lower position, after the molding process 12 is completed, includes an actuating rod locking device 176. Thus, the retaining element 96 including the actuating rod locking device 176 allows the air cylinder rod 134, such as the piston rod 134a with the cap presser 136, to remain in the pressing position 116b, i.e., the lower position, when, for example, the second die 64, i.e., the male die 64a or the upper die 64b, retracts from the first die 54 after the molding process 12 is completed.

[0077] As shown in FIG. 1B and described below with reference to FIGS. 7A-7C, in another embodiment, the restraining assembly 60 includes a spring assembly 184 and the restraining device 62 includes a spring-loaded plate 186. The spring assembly 184 includes the spring-loaded plate 186 coupled to an actuation locking arrangement 188 (see FIGS. 1B and 7B). The spring-loaded plate 186 includes a spring element 190 (see FIGS. 1B and 7B), such as a mating spring, coupled around a rod 192 (see FIGS. 1B and 7B), such as a stabilizing rod 192a (see FIGS. 1B and 7B), which is attached to a cap presser 194 (see FIGS. 1B and 7B).

[0078] A rod 192 (see FIGS. 7B and 7C), such as stabilizing rod 192 (see FIGS. 7B and 7C), has a first end 196a (see FIG. 7C), a second end 196b (see FIG. 7C), and a rod body 198 (see FIG. 7C) disposed between the first end 196a and the second end 196b. A rod 192, such as stabilizing rod 192, is compressible through an opening 200 (see FIG. 7B) in a flexible die tray 228 (see FIG. 7B) of the first die 54 and an opening 202 (see FIG. 7B) in an actuation locking device 188. A rod 192, such as stabilizing rod 192, may be constructed of a metallic material, such as aluminum or steel, or other suitable metallic material. A first end 196a of the rod 192, such as stabilizing rod 192, is coupled to a cap presser 194, also referred to as a plate in this embodiment. The cap presser 194 is preferably a semi-rigid cap presser 194a (see FIG. 7B) having an engagement surface 204 (see FIGS. 7A-7C) configured to engage a first surface 51a (see FIG. 7A) of the cap portion 50a (see FIG. 7A) of the composite molded blank 14 and to engage a cap 52 formed from the cap portion 50a. The cap presser 194, such as the semi-rigid cap presser 194a, is preferably in the form of a bar formed of aluminum, other suitable metallic material, or other suitable semi-rigid material. The cap presser 194, such as the semi-rigid cap presser 194a, in the form of an aluminum bar, has a thickness of, for example, 0.125 inches, or other suitable thickness. The spring element 190, such as a mating spring, is preferably formed of a metallic material, such as steel, including spring steel or stainless steel, or other suitable metallic material. The spring element 190 has a first end 206a (see FIG. 7B) coupled to the cap presser 194, a second end 206b (see FIG. 7B) coupled to the actuation locking device 188, and a coil body 208 (see FIG. 7B) formed between the first end 206a and the second end 206b.

[0079] A rod 192, such as stabilizing rod 192, is inserted into an internal opening 210 (see FIG. 7B) of a coil body 208 of a spring element 190, and the coil body 208 of the spring element 190 fits around a portion of the rod body 198 of a rod 192, such as stabilizing rod 192a. The spring element 190 pushes the rod 192, such as stabilizing rod 192a, with a cap presser 194 to apply an upward resistance force 92 (see FIG. 1B) against the cap portion 50a of the composite molding blank 14 and against the downward pressing force 90 (see FIG. 1A) applied by the second die 64. The spring-loaded plate 186 holds the cap portion 50a of the composite molding blank 14 in place before and during the molding process 12 and holds the cap 52 of a molded contoured composite structure 16, such as the highly contoured composite structure 18. A restraining device 62, such as a spring loaded plate 186, applies a mechanical force to the cap portion 50a and the cap 52 during the molding process 12, ie, the molding cycle.

[0080] An actuation locking device 188 (see FIG. 7B) is preferably disposed transversely to a rod 192, such as stabilizing rod 192a, and disposed about the rod 192, such as stabilizing rod 192a, below the first die 54 and below the die cavity 58, near the second end 196b (see FIG. 7B). The actuation locking device 188 is configured to couple to the rod 192, such as stabilizing rod 192a, and to secure or hold the rod 192, such as stabilizing rod 192a, in the pressed position 116c (see FIG. 1B).

[0081] The actuation locking device 188 includes an actuator 212 (see FIGS. 1B and 7B) configured and configured to actuate a rod lock 214 (see FIGS. 1B and 7B) to couple and secure or press firmly against one or more portions of a rod body 198 of a rod 192, such as stabilization rod 192a, to secure or hold a rod 192, such as stabilization rod 192a, in the pressed position 116c. The actuator 212 is actuated by an actuation force mechanism 216 (see FIG. 1B), such as a spring, compressed air pressure, or other suitable actuation force mechanism. The rod lock 214 may include a clamp, spring pin, lever, or other suitable locking element that is released by the actuator 212 to secure or hold a rod 192, such as stabilization rod 192a, in the pressed position 116c. In one embodiment, the actuation locking device 188 may be in the form of a cartridge assembly disposed transversely relative to a rod 192, such as stabilizing rod 192a, and the actuation locking device 188 is preferably automatic for locking and unlocking a rod 192, such as stabilizing rod 192a. When it is desired to unlock a rod 192, such as stabilizing rod 192a, and move it to the extended position 112c (see FIG. 1B), the actuation locking device 188 is unlocked to release the retention of a rod 192, such as stabilizing rod 192a, by the rod lock 214.

[0082] In this embodiment of the spring assembly 184, the restraining device 62 (see FIG. 7A), such as the spring loaded plate 186 (see FIG. 7A), is in an extended position 112 (see FIG. 7A), such as the extended position 112c (see FIG. 7A), in the die cavity 58 (see FIG. 7A) to restrain the cap portion 50a (see FIG. 7A) against the second die 64 (see FIG. 7A) and counteract the downward pressing force 90 of the second die 64, i.e., the male die 64a or the upper die 64b, during the forming of the composite molding blank 14 into the highly contoured composite structure 18. In this embodiment of the spring assembly 184, the retaining element 96 (see FIG. 1B) of the restraining assembly 60, which functions to hold or maintain the rod 192, such as the stabilizing rod 192a having the cap presser 194, in the pressing position 116c (see FIG. 1B), i.e., the lower position, after the forming process 12 is completed, includes an actuation locking device 188. Thus, the retaining element 96 constituting the actuation locking device 188 ensures that the rod 192, such as the stabilizing rod 192a having the cap presser 194, remains in the pressing position 116c, i.e., the lower position, for example, when the second die 64, i.e., the male die 64a or the upper die 64b, retracts from the first die 54 after the molding process 12 is completed.

[0083] 2A and 2B, FIG. 2A is a front perspective view of an example of a molding apparatus 10, such as in the form of a highly contoured stringer molding apparatus 10a of the present disclosure, showing a restraining assembly 60, such as in the form of a foam vacuum assembly 100 at the first die 54, and a portable carrier portion 218 separated from a molding machine portion 220. FIG. 2B is a front perspective view of a molding apparatus 10, such as in the form of a highly contoured stringer molding apparatus 10a of FIG. 2A, showing the portable carrier portion 218 coupled to the molding machine portion 220, and the first die 54 and second die 64 in an open position 222 (see also FIG. 10A) ready to receive a composite molding feedstock 14, such as a flat composite molding feedstock 14a. During the molding process 12, the first die 54 and second die 64 are in a closed position 224 (see FIG. 11A) when they are in contact with each other. Preferably, the forming apparatus 10, such as in the form of a highly contoured stringer forming apparatus 10a, is an automated forming apparatus 10b (see FIGS. 2A and 2B). As shown in FIG.

[0084] As shown in Figures 2A and 2B, a restraining assembly 60, such as in the form of a foam vacuum assembly 100, is disposed in the first die 54, and a restraining device 62, such as in the form of a compressible foam element 102, is disposed in the die cavity 58 of the first die 54 between a first element 55a (see Figure 2B) and a second element 55b (see Figure 2B) of a plurality of pairs 55 (see Figure 2B) of first die parts 56, such as die blocks 56a (see Figure 2B). As further shown in Figure 2A, the restraining device 62, such as in the form of a compressible foam element 102, is disposed in the die cavity 58 along the length direction 226 of the first die 54. The restraining device 62, such as in the form of a compressible foam element 102, is covered or surrounded by a vacuum bag 105 (see Figures 2A and 2B). As shown in FIGS. 2A and 2B, the foam vacuum assembly 100 further includes a vacuum source 106 coupled to the vacuum bag 105 via a vacuum line 108 having a control valve 110 .

[0085] As shown in Figures 2A and 2B, the first die 54 is supported on a flexible die tray 228 mounted on a portable carrier portion 218, which is removably coupled to a plurality of first anvils 230 (see Figure 2A) by removable couplings 232 (see Figure 2A). The first die 54 includes a plurality of first die portions 56 (see Figures 2A and 2B), which are individually displaceable from one another to form a variable die contour 234 (see Figure 2A). The first die portions 56 are mounted on a flexible die tray 228 formed of any suitable flexible material, such as a thin aluminum, synthetic material, or plastic material. The first die portions 56, such as in the form of die blocks 56a (see Figure 2B), are preferably side-by-side along the length 226 of the first die 54 (see Figure 2A) and the length of the flexible die tray 228, and are interconnected by connectors 241 (see Figure 4). The first die portion 56, such as in the form of a die block 56a, may comprise a relatively rigid material, such as a metal, including steel or stainless steel, or a ceramic, or other suitable relatively rigid material. The first die portion 56, such as in the form of a die block 56a, generally has a rectangular cross-sectional shape. However, the first die portion 56, such as in the form of a die block 56a, may have other suitable cross-sectional shapes.

[0086] The plurality of contour control actuators 78 (see FIGS. 2A and 2B) control the displacement of the plurality of first anvils 230 (see FIG. 2A) and individually control the displacement of the first die portion 56 of the first die 54 along the length direction 226 (see FIG. 2A). The plurality of forming actuators 80 (see FIGS. 2A and 2B) control the displacement of the plurality of second anvils 236 (see FIG. 2A) and individually control the displacement of the second die portion 66 of the second die 64 (see FIGS. 2A and 2B), such as the second die portion 66 of the pairs 65 (see FIG. 2B) of the second die 64. The plurality of contour control actuators 78 and the plurality of forming actuators 80 are controlled by a controller 74 (see FIGS. 1A, 2A, and 2B) of a control system 70 (see FIGS. 1A, 2A, and 2B). The controller controls the operation of the plurality of contour control actuators 78 and the plurality of forming actuators 80, as described above, using an operator input control device 84 (see FIG. 1A), a control program 82, such as an algorithm or software program (see FIG. 1A), and contour data 85 (see FIG. 1A) of a contoured composite structure 16, such as highly contoured composite structure 18, to be formed. Through operation of the controller 74, the first die portions 56 are individually displaced to collectively form a variable die contour 234 (FIGS. 1A and 2A) that corresponds to the contoured composite structure 16, such as highly contoured composite structure 18, to be formed. Additionally, the second die portions 66 are individually and sequentially displaced via operation of the controller 74 to apply a downward pressing force 90 (see FIGS. 1A and 8) to the composite molding feedstock 14, such as the flat composite molding feedstock 14a (see FIG. 2B), against the first die 54 throughout the molding process 12 when the second die 64 is closed against the first die 54. The restraining device 62 applies an upward resisting force 92 (see FIGS. 1A and 8) against the downward pressing force 90 to prevent or eliminate wrinkles in the cap 52 of the contoured composite structure 16, such as the highly contoured composite structure 18 being molded. FIG. 2A shows the portable carrier portion 218 decoupled from the molding machine portion 220 at the uncoupled position 238.Figure 2B shows the portable carrier section 218 coupled to the forming machine section 220 at a coupling location 239. As further shown in Figures 2A and 2B, a forming apparatus 10, such as the highly contoured stringer forming apparatus 10a, may employ a Cartesian xyz coordinate system 240 in which the x-axis corresponds to the longitudinal direction of the composite forming blank 14 and the formed contour extends along the y-axis.

[0087] As shown in FIG. 2A, the flexible die tray 228 of the first die 54 is supported on a plurality of spaced push rods 242, each mounted for vertical displacement on a beam 244. After completion of the molding process 12, the portable carrier portion 218 can be used to transport the first die 54 supporting the contoured composite structure 16, such as the molded highly contoured composite structure 18, to a secondary holding tool 246, such as a curing tool (see FIGS. 1A, 18A), or to place the contoured composite structure 16, such as an uncured skin, on a substrate 248 (see FIG. 1A). The contoured composite structure 16, such as the highly contoured composite structure 18, may be transferred or transported using other suitable equipment to other suitable devices or structures for additional processing or assembly.

[0088] As shown in Figures 2A and 2B, the second die 64 includes a tapered portion 68 or punch 68a attached to a flexible backing plate 250. The tapered portion 68 or punch 68a is preferably attached to and projects downwardly from a bottom portion 252 of the flexible backing plate 250 (see Figures 2A and 5A). The tapered portion 68 or punch 68a preferably extends along a length direction 254 (see Figure 2A) of the flexible backing plate 250. The tapered portion 68 or punch 68a may be formed of a suitable rigid material, such as a metal, including steel or stainless steel, other suitable metals, ceramics, composite materials, or other suitable rigid materials. The flexible backing plate 250 may include, for example, but not limited to, a relatively thin aluminum, or other similar metal or flexible synthetic material. The flexible backing plate 250 is attached to a plurality of second anvils 236 (see FIG. 2A) to permit sliding movement along the x-axis by the second die portion 66, which may be in the form of a series of slide plates 255 (see FIG. 2A). FIG. 2A further shows a first vertical support 256a displaceable along the y-axis by the contour control actuator 78, and a second vertical support 256b displaceable along the y-axis by the shaping actuator 80. FIG. 2A also shows a plurality of first anvils 230 secured to a first slide arm 257a using a first bracket 258a, and a plurality of second anvils 236 secured to a second slide arm 257b using a second bracket 258b.

[0089] 3, which is an enlarged right perspective view of an exemplary embodiment of a molding apparatus 10, such as the highly contoured stringer molding apparatus 10a of the present disclosure, showing the first die 54 and the second die 64 in an open position 222. This position is a position prior to placing a composite molding blank 14 (see FIG. 2B), such as a flat composite molding blank 14a (see FIG. 2B), between the first die 54 and the second die 64 and on the first die 54. In this figure, the restraining assembly 60 includes a foam vacuum assembly 100 and the restraining device 62 includes a compressible foam element 102 disposed in the die cavity 58 of the first die 54. Preferably, the molding apparatus 10, such as in the form of the highly contoured stringer molding apparatus 10a, is an automated molding apparatus 10b (see FIG. 3).

[0090] FIG. 3 illustrates a first die 54, i.e., lower die 54b, with a plurality of pairs 55 of first die parts 56, such as in the form of die blocks 56a, disposed on a flexible die tray 228. The flexible die tray 228 is coupled to a plurality of first anvils 230. As shown in FIG. 3, a constraining device 62 including a compressible foam element 102 is disposed in the die cavity 58 between a first element 55a and a second element 55b of a pair 55 of first die parts 56, such as die blocks 56a. The constraining device 62 including a compressible foam element 102 is disposed in the die cavity 58 along a length direction 226 (see FIG. 2A) of the first die 54. The constraining device 62 including a compressible foam element 102 is covered or surrounded by a vacuum bag 105. The vacuum bag 105 of the foam vacuum assembly 100 is coupled or connected to a vacuum source 106 (see FIGS. 2A and 2B) via a vacuum line 108 (see FIGS. 2A and 2B).

[0091] 3 further illustrates a second die 64, or upper die 64b, with a plurality of pairs 65 of second die portions 66 positioned above the first die 54, or lower die 54b. The second die 64 includes a tapered portion 68, or punch 68a, that protrudes from a bottom portion 252 of a flexible backing plate 250. FIG. 3 further illustrates the flexible backing plate 250 attached to a plurality of second anvils 236.

[0092] 4, which is a perspective front view of a contoured composite structure 16, such as a highly contoured composite structure 18, e.g., a hat-shaped stringer 34a, formed by an exemplary embodiment of a forming apparatus 10, such as the highly contoured stringer forming apparatus 10a shown in FIGS. 1A, 2A, 2B, and 3. The hat-shaped stringer 34a may be used in the aircraft industry, for example, but not limited to, to reinforce or support various structures, such as a fuselage 402 (see FIG. 19), a wing 406 (see FIG. 19), a vertical stabilizer 412 (see FIG. 19), a horizontal stabilizer 414 (see FIG. 19), or other aircraft structures. FIG. 3 illustrates the hat-shaped stringer 34a, whose cross-sectional shape 40 is a hat shape 42. The hat-shaped stringer 34a may have other suitable cross-sectional shapes, such as a square, a rounded cap, or other geometric or angled shapes.

[0093] As shown in FIG. 4, the contoured hat section 43 includes a cap 50 and a side portion 260, also referred to as a web, and further includes a flange 262, such as an outwardly extending flange. The cap 50 of the hat stringer 34a shown in FIG. 4 is formed using a forming apparatus 10, such as the highly contoured stringer forming apparatus 10a of the present disclosure, and a forming process 12, and the cap is in a wrinkle-free state 46, i.e., free of wrinkles and fiber distortion. As shown in FIG. 4, the hat stringer 34a has a contour 30, such as a complex contour 30a, or out-of-plane contour or out-of-plane curvature, along its major axis 264 or length. FIG. 4 further illustrates a Cartesian xyz coordinate system 240. The cap 52 of the hat stringer 34a preferably has a contour radius 98 (see FIG. 1A) in the range of 500 inches to 1000 inches, and more preferably has a contour radius 98 in the range of 500 inches to 750 inches.

[0094] 5A-5C, Fig. 5A is a schematic front view of an exemplary embodiment of a molding apparatus 10 of the present disclosure having a constraining assembly 60 in the form of a foam vacuum assembly 100, with a constraining device 62 including a compressible foam element 102. Fig. 5B is a schematic enlarged front view of the constraining assembly 60 constituting the foam vacuum assembly 100 shown in Fig. 5A. Fig. 5C is a schematic enlarged side view of the constraining assembly 60 constituting the foam vacuum assembly 100 shown in Fig. 5B.

[0095] 5A-5C, and as described above, foam vacuum assembly 100 includes a compressible foam element 102, a vacuum bag 105 surrounding compressible foam element 102, a vacuum source 106 coupled to vacuum bag 105 via a vacuum line 108 or vacuum hose, and a control valve 110 coupled to vacuum line 108. As shown in FIG. 5B, a first end 109a of vacuum line 108 is coupled to vacuum bag 105 and a second end 109b of vacuum line 108 is coupled to vacuum source 106.

[0096] As shown in FIG. 5A, a restraining device 62, such as a compressible foam element 102, is in an extended position 112, such as extended position 112a, in a die cavity 58 of a first die 54 and is surrounded by a vacuum bag 105. The compressible foam element 102 is positioned between a first die portion 56 (see FIG. 5A), such as a die block 56a (see FIG. 5A). The first die portion 56 is attached to a flexible die tray 228 (see FIG. 5A). A first end 103a (see FIG. 5A) of the compressible foam element 102 is restrained via a vacuum bag 105 against a first surface 51a of a cap portion 50a of a composite molding blank 14, such as a flat composite molding blank 14a, and a second end 103b (see FIG. 5B) of the compressible foam element 102 is positioned near a floor 59 of the die cavity 58 via the vacuum bag 105. FIG. 5B shows a body 104 of the compressible foam element 102. 5A, a tapered portion 68, such as punch 68a, of the second die 64 is coupled to a bottom portion 252 of the flexible backing plate 250 and is positioned above the second surface 51b of the cap portion 50a of the composite molding blank 14. The first die 54 and the second die 64 are in the open position 222 (see FIG. 5A).

[0097] Figures 5B and 5C show the compressible foam element 102 including the compressible foam material 122. As further shown in Figures 5B and 5C, a vacuum bag 105 surrounds the compressible foam element 102 such that a gap 266 exists between an outer surface 268 of the compressible foam element 102 and an inner surface 270 of the vacuum bag 105 when no vacuum pressure 118 (see Figure 1B) is applied to the compressible foam element 102. Figure 5B further shows the first end 94a, second end 94b, and body 95 of the restraining device 62 including the compressible foam element 102.

[0098] 6A-6E, FIG. 6A shows a schematic front view of an exemplary embodiment of a molding apparatus 10 of the present disclosure, the molding apparatus including a restraining assembly 60 in the form of a pneumatic assembly 132 having an air cylinder 146, illustratively a single acting spring return air cylinder 146a, and the restraining device 62 including an air cylinder rod 134 having a cap presser 136. FIG. 6B shows a schematic enlarged front view of the restraining assembly 60 constituting the pneumatic assembly 132 shown in FIG. 6A. FIG. 6C shows a schematic enlarged side view of the restraining assembly 60 constituting the pneumatic assembly 132 shown in FIG. 6B. FIG. 6D shows a schematic front view of an exemplary embodiment of a molding apparatus 10 of the present disclosure, the molding apparatus including a restraining assembly 60 in the form of a pneumatic assembly 132 having an air cylinder 146, illustratively a double acting pneumatic cylinder 146b, and the restraining device 62 including an air cylinder rod 134 having a cap presser 136. FIG. 6E shows a schematic front view of an exemplary embodiment of a molding apparatus 10 of the present disclosure, which includes a restraining assembly 60 in the form of a pneumatic assembly 132 having an air cylinder 146, which is, by way of example, a rod-lock air cylinder 146c, and a restraining device 62 including an air cylinder rod 134 having a cap presser 136.

[0099] As shown in FIGS. 6A-6E and as described above, the restraint assembly 60 in the form of a pneumatic assembly 132 includes a restraint device 62 having an air cylinder rod 134 with a cap presser 136, an air cylinder 146 coupled to the air cylinder rod 134, and an air supply 158 coupled to the air cylinder 146 via one or more air supply lines 154 and one or more ports 157.

[0100] As shown in Figures 6A, 6D, and 6E, a restraining device 62, such as an air cylinder rod 134 having a cap presser 136, is in an extended position 112, such as extended position 112b, within or partially within the die cavity 58 of the first die 54. The air cylinder rod 134 having the cap presser 136 is disposed between the first die portions 56 (see Figures 6A, 6D, and 6E), such as die blocks 56a (see Figures 6A, 6D, and 6E). The first die portions 56 are attached to a flexible die tray 228 (see Figures 6A, 6D, and 6E). The engagement surface 144 (see also FIGS. 6A-6E) of the cap presser 136 (see FIGS. 6A-7E) engages and is constrained against a first surface 51a (see FIGS. 6A, 6D, and 6E) of a cap portion 50a (see FIGS. 6A, 6D, and 6E) of a composite molding blank 14 (see FIGS. 6A, 6D, and 6E), such as a flat composite molding blank 14a (see FIGS. 6A, 6D, and 6E). As further shown in FIGS. 6A, 6D, and 6E, a tapered portion 68, such as a punch 68a of the second die 64, is coupled to a bottom portion 252 of the flexible backing plate 250 and is positioned above the second surface 51b of the cap portion 50a of the composite molding blank 14. The first die 54 and the second die 64 are in an open position 222 (see FIGS. 6A, 6D, and 6E). FIG. 6B shows the first end 94 a , second end 94 b , and body 95 of the restraining device 62 , which includes an air cylinder rod 134 having a cap presser 136 .

[0101] Figures 6B and 6C show an air cylinder rod 134, such as piston rod 134a, that is movable in an up and down direction 142 (see Figure 6B). As shown in Figure 6B, the air cylinder rod 134 has a first end 138a coupled to a cap presser 136, such as semi-rigid cap presser 136a, a second end 138b coupled to a piston head 135 within an air cylinder 146, and a rod body 140. As shown in Figure 6C, the air cylinder 146 includes a first end 148a, a second end 148b, and a cylinder tube 150 disposed between the first end 148a and the second end 148b. The first end 148a of the air cylinder 146 has an opening 152 (see FIGS. 6B-6C) that is configured to receive and receives the second end 138b and rod body 140 of the air cylinder rod 134 as the air cylinder rod 134 is pressed or moved downwardly from the extended position 112b (see FIGS. 1B and 6A) to one or more intermediate pressed positions 114b (see FIG. 1B) and to a pressed position 116b (see FIG. 1B), such as a fully pressed position.

[0102] As shown in Figures 6A-6E, the pneumatic assembly 132 further includes an air supply line 154, such as a first air supply line 154a (see Figure 6B). As shown in Figure 6B, the air supply line 154 has a first end 156a coupled to the air cylinder 146 via a port 157, such as a first port 157a, and a second end 156b coupled to an air source 158 including compressed air 160. As shown in Figures 1B and 6B, the pneumatic assembly 132 further includes a pressure control valve 164 coupled to the air supply line 154 for turning on and off air pressure 162 (see Figure 1B) from the air source 158.

[0103] In one embodiment, as shown in Figures 6A-6C, the air cylinder 146 is a single acting spring-return air cylinder 146a having one air supply line 154, such as a first air supply line 154a, connected between an air supply source 158 and a first port 157a of the single acting spring-return air cylinder 146a. As shown in Figure 6B, the single acting spring-return air cylinder 146a includes a spring 166, such as a mating spring, disposed within the cylinder tube 150 of the air cylinder 146 and mated around the rod body 140 of the air cylinder rod 134 between an interior first end 148a (see Figure 6C) of the air cylinder 146 and the piston head 135. How the single acting spring-return air cylinder 146a operates has been described in detail above. When using a single-acting spring-return air cylinder 146a, after completion of the molding process 12, i.e., molding process 12b (see FIG. 13A), the retaining element 96 (see FIG. 1B) of the restraining assembly 60, which functions to hold or maintain the air cylinder rod 134, such as the piston rod 134a with the cap presser 136, downward, exerts a spring return 168 (see FIG. 1B) and a spring force 170 (see FIG. 1B) as a result of a lack of air pressure 162a (see FIG. 1B), which is a state in which the air pressure 162 is stopped by the pressure control valve 164 and no air pressure 162 is applied to the air cylinder rod 134, such as the piston rod 134a with the cap presser 136.

[0104] In another embodiment, as shown in FIG 6D, the air cylinder 146 is a double-acting air cylinder 146b, which has two air supply lines 154, such as a first air supply line 154a and a second air supply line 154b, connected between an air supply source 158 and the double-acting air cylinder 146b. As shown in FIG 6D, the first air supply line 154a is connected to the double-acting air cylinder 146b with a first pressure control valve 164a, and the second air supply line 154b is connected to the double-acting air cylinder 146b with a second pressure control valve 164b. As shown in FIG 6D, the first air supply line 154a is coupled to a lower hole 172 in the cylinder tube 150 of the double-acting air cylinder 146b via a first port 157a. As further shown in FIG. 6D, the second air supply line 154b is coupled to an upper hole 174 in the cylinder tube 150 of the double-acting air cylinder 146b through a second port 157b. The operation of the double-acting air cylinder 146b has been described in detail above. When using the double-acting air cylinder 146b, the retaining element 96 of the restraining assembly 60, which functions to hold or maintain the air cylinder rod 134, such as the piston rod 134a with the cap presser 136, downward after the molding process 12 is completed, applies air pressure 162b (see FIG. 1B) to the upper hole 174 of the double-acting air cylinder 146b. The application of air pressure 162b to the upper hole 174 can push down the air cylinder rod 134, such as the piston rod 134a with the cap presser 136, to maintain or hold the air cylinder rod in the pressed position 116b, i.e., the base position or the lower position. FIG. 6D further illustrates the first end 94 a , second end 94 b , and body 95 of the restraining device 62 , which includes an air cylinder rod 134 having a cap presser 136 .

[0105] In another embodiment, as shown in FIG. 6E, the air cylinder 146 includes a rod-lock air cylinder 146c. As shown in FIG. 6E, the rod-lock air cylinder 146c includes an actuating rod locking device 176 disposed on the exterior of the first end 148a of the air cylinder 146. The actuating rod locking device 176 is configured to couple to the air cylinder rod 134 to secure or hold the air cylinder rod 134 in the pressed position 116b (see FIG. 1B). As shown in FIG. 6E, the actuating rod locking device 176 includes an actuator 178 configured to actuate a rod lock 180 including a clamp to couple and secure or press the rod lock against one or more portions of the air cylinder rod 134 to secure or hold the air cylinder rod 134 in the pressed position 116b. The actuator 178 is actuated by an actuating force mechanism 182 (see FIG. 6E), such as a spring. When using this embodiment of the air cylinder 146, the retaining element 96 (see FIG. 1B) of the restraining assembly 60, which functions to hold or maintain the air cylinder rod 134, such as the piston rod 134a with the cap presser 136, in the pressed position 116b, i.e., the lower position, after the molding process 12 is completed, includes an actuating rod locking arrangement 176. FIG. 6E further illustrates the first end 94a, second end 94b, and body 95 of the restraining device 62, which includes the air cylinder rod 134 with the cap presser 136.

[0106] 7A-7C, Fig. 7A is a schematic front view of an exemplary embodiment of a molding apparatus 10 of the present disclosure having a restraining assembly 60 in the form of a spring assembly 184, with a restraining device 62 including a spring-loaded plate 186. Fig. 7B is a schematic enlarged front view of the restraining assembly that constitutes the spring assembly 184 shown in Fig. 7A. Fig. 7C is a schematic enlarged side view of the restraining assembly that constitutes the spring assembly 184 shown in Fig. 7B.

[0107] 7A-7C, and as described above, the spring assembly 184 includes a restraining device 62 having a spring loaded plate 186 coupled to an actuation locking arrangement 188. As shown in FIG. 7B, the spring loaded plate 186 includes a spring element 190, such as a mating spring, coupled around a rod 192, such as stabilizing rod 192a, which is attached to a cap presser 194.

[0108] As shown in FIG 7A, a restraining device 62, such as a spring loaded plate 186, is in an extended position 112, such as extended position 112c, within or substantially within the die cavity 58 of the first die 54. FIG 7A shows a first end 94a, a second end 94b, and a body 95 of the restraining device 62, including the spring loaded plate 186. The spring loaded plate 186 is disposed between first die portions 56 (see FIG 7A), such as die blocks 56a (see FIG 7A). The first die portions 56 are attached to a flexible die tray 228 (see FIG 7A-7C). The engagement surface 204 (see also FIGS. 7A-7C) of the cap presser 194 (see FIGS. 7A-7C) engages and is constrained against a first surface 51a (see FIG. 7A) of a cap portion 50a (see FIG. 7A) of a composite molding blank 14 (see FIG. 7A), such as a flat composite molding blank 14a (see FIG. 7A). As further shown in FIG. 7A, a tapered portion 68, such as a punch 68a of the second die 64, is coupled to a bottom portion 252 of a flexible backing plate 250 and is positioned above the second surface 51b of the cap portion 50a of the composite molding blank 14. The first die 54 and the second die 64 are in an open position 222 (see FIG. 7A).

[0109] As shown in Figure 7B, a rod 192, such as stabilizing rod 192, has a first end 196a, a second end 196b, and a rod body 198, with the first end 196a of the rod 192, such as stabilizing rod 192, coupled to a cap presser 194, such as semi-rigid cap presser 194a. As further shown in Figure 7B, the rod 192, such as stabilizing rod 192, is inserted into an opening 200 in the flexible die tray 228 and an opening 202 in the actuation locking device 188. The spring element 190 (see FIGS. 7B and 7C) includes a first end 206a (see FIG. 7C) coupled to the cap presser 194 (see FIGS. 7B and 7C), a second end 206b (see FIG. 7C) coupled to the actuation locking device 188 (see FIGS. 7B and 7C), and a coil body 208 (see FIG. 7C) having an internal throughbore 210 (see FIG. 7C) through which a rod body 198 (see FIGS. 7B and 7C) of a rod 192, such as stabilization rod 192a, is inserted.

[0110] As shown in FIG. 7B, the actuation lock device 188 is disposed transversely relative to the rod 192, such as the stabilizing rod 192a, and below the flexible die tray 228. The actuation lock device 188 is configured to couple to the rod 192, such as the stabilizing rod 192a, to secure or hold the rod 192, such as the stabilizing rod 192a, in the pressed position 116c (see FIG. 1B). The actuation lock device 188 includes an actuator 212 (see FIGS. 7B and 7C) configured to actuate a rod lock 214 (see FIGS. 7B and 7C) to couple and secure or press firmly against one or more portions of the rod 192, such as the stabilizing rod 192a, to secure or hold the rod 192, such as the stabilizing rod 192a, in the pressed position 116c (see FIG. 1B). The actuator 212 is actuated by an actuation force mechanism 216 (see FIGS. 7B and 7C), such as a spring, compressed air, or other suitable actuation force mechanism. As shown in FIGS. 7B and 7C, the rod lock 214 is in the form of a clamp 214a. However, the rod lock 214 may include a spring pin, lever, or other suitable locking element that is released by the actuator 212 to secure or hold a rod 192, such as stabilization rod 192a, in the depressed position 116c.

[0111] 8, which diagrammatically illustrates a force diagram 272 illustrating various forces applied in an exemplary embodiment of a forming apparatus 10, such as the highly contoured stringer forming apparatus 10a, during the forming process 12. FIG. 8 is a front view of a forming apparatus 10, such as the highly contoured stringer forming apparatus 10a, in which a composite laminate forming blank 14, such as a composite laminate forming blank 14b, is formed into a contoured hat portion 43 of a highly contoured composite structure 18, such as a hat stringer 34a, having a cap 52, a first side 260a, a second side 260b, a first flange 262a, and a second flange 262b. In FIG. 8, the composite laminate forming blank 14, such as a composite laminate forming blank 14b, is positioned and restrained between a tapered portion 68, such as a punch 68a of the second die 64, a restraining device 62, and a first die portion 56, such as a die block 56a of the first die 54.

[0112] As shown in FIG. 8, the restraining device 62 takes the form of a compressible foam element 102 and the restraining assembly 60 takes the form of a foam vacuum assembly 100. As shown in the figure, the restraining device 62 in the form of a compressible foam element 102 is surrounded by a vacuum bag 105 and pressed at an intermediate pressing location 114a in the die cavity 58. As shown and described above in connection with FIGS. 5A-5C, the restraining device 62 and vacuum bag 105 are coupled to other components of the foam vacuum assembly 100, such as a vacuum source 106, a vacuum line 108, and a control valve 110. As shown in FIG. 8, a first end 103a of the compressible foam element 102 is pressed against a first surface 51a of the cap portion 50a from which the cap 52 is to be formed.

[0113] 8, a tapered portion 68 of a second die 64, such as a punch 68a, applies a downward pressing force 90 against the second surface 51b of the cap portion 50a, or against the cap 52 formed from the cap portion 50a, and against a restraining device 62, such as a compressible foam element 102. The downward pressing force 90 applied by the tapered portion 68 of the second die 64, such as a punch 68a, against the cap portion 50a of the composite molding blank 14, or against the cap 52 formed from the cap portion 50a, is preferably in the range of 20 pounds per square inch (psi) to 380 psi. However, other suitable downward pressing forces psi may be used depending on the composite molding blank 14 and the contoured composite structure 16, such as the highly contoured composite structure 18, desired to be formed.

[0114] 8 further illustrates how as the tapered portion 68 moves downwardly into the die cavity 58, the second die 64, such as the punch 68a, exerts a first downward force 90a against the first side 260a of the contoured hat 43 and against the left die block 56b, i.e., lower left pallet, of the first die 54, causing the left die block 56b to move laterally outward in a first lateral direction 274. FIGURE 8 further illustrates how as the tapered portion 68 moves downwardly into the die cavity 58, the second die 64, such as the punch 68a, exerts a second downward force 90b against the second side 260b of the contoured hat 43 and against the right die block 56c, i.e., lower right pallet, of the first die 54, causing the right die block 56c to move laterally outward in a second lateral direction 276.

[0115] 8, the left die block 56b, or lower left pallet, applies a first upward force 278 to the first flange 262a of the highly contoured composite structure 18, such as hat stringer 34a, formed by the composite molding feedstock 14. The first upward force 278 applied by the left die block 56b, or lower left pallet, to the first flange 262a is preferably in the range of 5 pounds per square inch (psi) to 90 psi, although other suitable upward force psi values ​​may be used.

[0116] 8, the right die block 56c, or lower right pallet, applies a second upward force 280 against the second flange 262b of the highly contoured composite structure 18, such as the hat stringer 34a, formed by the composite molding feedstock 14. The second upward force 280 applied by the right die block 56c, or lower right pallet, against the second flange 262b is preferably in the range of 5 pounds per square inch (psi) to 90 psi, although other suitable upward force psi values ​​may be used.

[0117] 8, the restraining device 62, such as a compressible foam element 102, of the restraining assembly 60, such as a foam vacuum assembly 100, exerts an upward resistance force 92 against the cap portion 50a, or a cap 52 formed therefrom, and against the downward pressure force 90 of the tapered portion 68 of the second die 64, such as a punch 68a. The upward resistance force 92 exerted by the restraining assembly 60, and in particular the restraining device 62, against the cap portion 50a, or a cap 52 formed therefrom, is preferably in the range of 10 pounds per square inch (psi) to 200 psi. However, other suitable upward resistance forces psi may be used depending on the composite molding feedstock 14 and the contoured composite structure 16, such as the highly contoured composite structure 18, desired to be formed. The upward resistance force 92 of the restraint device 62 and the downward pressing force 90 of the tapered portion 68 of the second die 64, such as the punch 68a, act to clamp or restrain the cap portion 50a of the composite molding material 14, or the cap 52 formed by the cap portion 50a, to relieve stress from the cap portion 50a or the cap 52 and to prevent 44 (see FIG. 1A) or reduce 45 (see FIG. 1A) wrinkles in the cap portion 50a or the cap 52.

[0118] 9A, there is shown a flow diagram illustrating an exemplary embodiment of a method 350 of the present disclosure. In another embodiment of the present disclosure, a method 350 is provided for constraining a composite molding feedstock 14 and forming the composite molding feedstock 14 into a contoured composite structure 16, such as a highly contoured composite structure 18.

[0119] The blocks shown in FIG. 9A depict steps and / or portions thereof, or elements, and the lines connecting the various blocks do not depict a particular order or dependency of the steps and / or portions thereof, or elements. FIG. 9A and the disclosure illustrating the steps of the method 350 described herein do not necessarily dictate the order in which these steps are performed. Rather, while one example order is shown, it should be understood that the order of these steps can be changed as appropriate. Thus, some of the steps can be performed in a different order or simultaneously.

[0120] 9A , the method 350 includes the step 352 of placing the composite molding feedstock 14 between and in contact with a first die 54 and a second die 64 of a molding apparatus 10, such as a highly contoured stringer molding apparatus 10a, as described in detail above. As will be further described, in one embodiment, the molding apparatus 10 includes a first die 54 having a plurality of pairs 55 of first die portions 56 spaced apart from one another to define a die cavity 58. The first die 54 further includes a restraint assembly 60 having a restraint device 62 disposed in the die cavity 58, as described above, that contacts the composite molding feedstock 14 via a vacuum bag 105, and in particular, a cap portion 50a of the composite molding feedstock 14, such as a first surface 51a of the cap portion 50a of the composite molding feedstock 14, via the vacuum bag 105, when the composite molding feedstock 14 is disposed between and on the first die 54 and the second die 64.

[0121] In step 352 of placing the composite molding material 14 (see FIG. 9A), the composite molding material 14 is placed between and in contact with the first die 54 and the second die 64, which in one embodiment has a restraining assembly 60, which is a foam vacuum assembly 100, and a restraining device 62, which is a compressible foam element 102.

[0122] 1B and as described above, the foam vacuum assembly 100 includes a compressible foam element 102, a vacuum bag 105 surrounding the compressible foam element 102, a vacuum source 106 coupled to the vacuum bag 105 via a vacuum line 108, and a control valve 110. As the second die 64 retracts away from the first die 54, the vacuum bag 105 is designed to hold and press the compressible foam element 102 in a pressed position 116a so that the compressible foam element 102 does not re-expand to an expanded position 112a and unnecessarily move the highly contoured composite structure 18 upward. A vacuum pressure 118 is applied against the compressible foam element 102, and the vacuum bag 105 maintains and holds the compressible foam element 102 in the pressed position 116a until the highly contoured composite structure 18 is removed from the first die 54. Once the highly contoured composite structure 18 is removed from the first die 54, the vacuum pressure 118 is turned off or released, thereby allowing the compressible foam element 102 to expand back to the expanded position 112a.

[0123] The compressible foam element 102 may be a single use compressible foam element 102a, which is removed from the first die 54 of the molding apparatus 10 after one or a single use for a single molding process 12. Alternatively, the compressible foam element 102 may be a multiple use compressible foam element 102b, which is designed for more than one or multiple uses in the molding apparatus 10 and can be used for multiple molding processes 12. The compressible foam element 102 may be removably mounted in the die cavity 58 of the first die 54 to facilitate removal of the compressible foam element 102 for cleaning or repair, or to facilitate removal of the compressible foam element 102 for replacement with an unused or new compressible foam element.

[0124] The compressible foam element 102 includes a compressible foam material 122. As shown in FIG. 1B and as described above, the compressible foam material 122 may include an open cell foam 124, such as polyurethane foam 124a, latex rubber foam 124b, or other suitable open cell foam. Preferably, the open cell foam 124 has a compressible strength of 3 lb / ft 3 (3 pounds / cubic foot)~13 lb / ft 3 The foam is in the form of a high density foam 126a (see FIG. 1B) having a density 128a (see FIG. 1B) in the range of 13 pounds per cubic foot.

[0125] 1B, the compressible foam material 122 may also include a closed cell foam 130, such as a polyethylene foam 130a, such as an expanded polyethylene foam, a polystyrene foam 130b, such as an expanded polystyrene foam, a polypropylene foam 130c, such as an expanded polypropylene foam, a neoprene foam rubber 130d, or other suitable closed cell foam. Preferably, the closed cell foam 130 has a foam strength of 2 lb / ft 3 (2 pounds / cubic foot)~10 lb / ft 3 The foam is in the form of a high density foam 126b (see FIG. 1B) having a density 128b (see FIG. 1B) in the range of 10 (10 pounds per cubic foot).

[0126] The densities 128a, 128b selected for the compressible foam material 122 of the compressible foam element 102 are determined by the type of composite molding feedstock 14 used and the type of contoured composite structure 16, such as the highly contoured composite structure 18, or part being molded using the molding apparatus 10 and molding process 12.

[0127] In placing the composite molding blank 14 between and in contact with the first die 54 and the second die 64 in step 352 (see FIG. 9A), the first die 54 includes a restraining assembly 60, which in another embodiment is a pneumatic assembly 132, and a restraining device 62 including an air cylinder rod 134 having a cap presser 136. As shown in FIG. 1B, the pneumatic assembly 132 includes an air cylinder rod 134 having a cap presser 136, an air cylinder 146 coupled to the air cylinder rod 134, and an air supply 158 coupled to the air cylinder 146 via one or more air supply lines 154 and one or more ports 157.

[0128] In placing the composite molding blank 14 between and in contact with the first die 54 and the second die 64 in step 352 (see FIG. 10A), the first die 54 includes a restraining assembly 60, which in another embodiment is a spring assembly 184, and a restraining device 62 including a spring-loaded plate 186. As shown in FIG. 1B, the spring assembly 184 includes the spring-loaded plate 186, which includes a spring element 190 (see FIG. 7B), a stabilizing rod 192 (see FIG. 7B), and a cap presser 194 (see FIG. 7B).

[0129] As shown in Figure 1A, molding apparatus 10 further includes a control system 70 that operatively controls operation 72 of molding apparatus 10, including controlling the operation of first die 54 and second die 64 in coordination with the operation of constraint assembly 60. Control system 70 is described in detail above in connection with Figure 1A.

[0130] As shown in FIG. 9A, the method 350 further includes a step 354 of forcing or squeezing the composite molding material 14 into the die cavity 58 of the molding apparatus 10 to form the cap 52 and the contoured hat portion 43 having the side portion 256.

[0131] As shown in FIG. 9A, the method 350 further includes a step 356 of constraining the cap 52 using the constraining device 62 as the contoured hat portion 43 is formed, and applying an upward resistance force 92 using the constraining device 62 against the cap 52 and against a downward pressing force 90 applied by the second die 64 to provide stress transfer 49 (see FIG. 1A) to transfer stress away from the cap 52 and provide wrinkle prevention 44 (see FIG. 1A) to prevent wrinkle formation or fiber distortion in the cap 52. The downward pressing force 90 presses the cap 52 downward, presses the constraining device 62 downward, and moves one or more of the pairs 55 of the first die portion 56, e.g., the left die block 56b (see FIG. 8) and the right die block 56c (see FIG. 8), laterally outward. After the contoured hat portion 43 is formed, the molding process 12 may form the remaining portion 50b (see FIG. 1A) of the composite molding blank 14. The restraint assembly 60, and in particular the restraint device 62, can maintain the cap portion 50a of the composite molding material 14 and the cap 52 in a restrained position during the molding process 12 to achieve wrinkle prevention 44 (see FIG. 1A) that prevents wrinkles from forming or fiber distortion in the cap portion 50a of the composite molding material 14, and thus prevents wrinkles from forming or fiber distortion in the cap 52 of a contoured composite structure 16, such as the highly contoured composite structure 18, to form the cap 52 in a wrinkle-free state 46.

[0132] As shown in Figure 9A, the method 350 further includes forming 358 a highly contoured composite structure 18 having a cap 52 in a fabric free state 46. The step 358 of forming a highly contoured composite structure 18 having a cap 52 in a fabric free state 46 further includes forming a highly contoured composite structure 18 including one or more of stringers 34, such as hat stringer 34a, aircraft stringer 34b, hat aircraft stringer 34c, fuselage stringer 34d, keel stringer 34e, wing stringer 34f, or stabilizer stringer 34g, one or more of stiffening members 36, such as hat stiffening member 36a or other suitable stiffening member, a wing spar 38, or other suitable highly contoured composite structure, as shown in Figure 1A. Preferably, the highly contoured composite structure 18 has a profile radius 98 (see FIG. 1A) in the range of 500 inches to 1000 inches, and more preferably has a profile radius 98 in the range of 500 inches to 750 inches.

[0133] 9A, the method 350 further includes a step 360 of holding the constraining device 62 using a holding element 96 of the constraining assembly 60 to prevent the constraining device 62 from pushing up the highly contoured composite structure 18 as the second die 64 retracts. As mentioned above, when the constraining assembly 60 is a foam vacuum assembly 100, the holding element 96 preferably includes a vacuum bag 105 to which a vacuum pressure 118 (see FIG. 1B) is applied, the vacuum bag surrounding the compressible foam element 102 and designed to maintain or hold the compressible foam element 102 in a pressed position 116a.

[0134] As mentioned above, when the restraining assembly 60 is a pneumatic assembly 132, in one embodiment the retaining element 96 may utilize a spring return 168 (see FIG. 1B) and a spring force 170 (see FIG. 1B) applied to the pneumatic cylinder rod 134 to hold the pneumatic cylinder rod 134 in the depressed position 116b (see FIG. 1B), and the pneumatic cylinder 146 is a single acting spring return pneumatic cylinder 146a (see FIG. 1B). When the restraining assembly 60 is a pneumatic assembly 132, in another embodiment the retaining element 96 may utilize an air pressure application 162b (see FIG. 1B) applied to the pneumatic cylinder rod 134 to hold the pneumatic cylinder rod 134 in the depressed position 116b, and the pneumatic cylinder 146 is a double acting pneumatic cylinder 146b (see FIG. 1B). In another embodiment, when the restraint assembly 60 is a pneumatic assembly 132, the retaining element 96 may include an actuating rod locking device 176 (see FIG. 1B) that holds the air cylinder rod 134 in the pressed position 116b, and the air cylinder 146 is a rod locking air cylinder 146c (see FIG. 1B).

[0135] As described above, when the restraint assembly 60 is the spring assembly 184, the retaining element 96 includes an actuating locking device 188 (see FIG. 1B) coupled to the spring-loaded plate 186, which is designed to maintain or hold the spring-loaded plate 186 in the pressed position 116c (see FIG. 1B).

[0136] After retaining 360 the restraining device 62, the method 350 may optionally include removing the highly contoured composite structure 18 from the first die 54 and releasing the retaining element 96 such that the restraining device 62 moves upward from the pressing position 116 (see FIG. 1B) to the extended position 112 (see FIG. 1B). The method 350 may further optionally include moving one or more pairs 55 of the first die portions 56, such as the left die block 56b (see FIG. 8) and the right die block 56c (see FIG. 8), laterally inwardly back to their original positions. The method 350 may further optionally include moving the contoured composite structure 16, such as the highly contoured composite structure 18, to one of a secondary holding tool 246, such as a curing tool, a substrate 248, such as an uncured skin, or other suitable structure for holding the contoured composite structure 16, such as the highly contoured composite structure 18, for further processing or assembly.

[0137] 9B, there is shown a flow diagram illustrating an exemplary embodiment of a method 370 of the present disclosure. In an embodiment of the present disclosure, a method 370 is provided for forming an aircraft stringer 34b having a cap 52 in a wrinkle-free condition 46 (see FIG. 1A).

[0138] The blocks shown in FIG. 9B depict steps and / or portions thereof, or elements, and the lines connecting the various blocks do not depict a particular order or dependency of the steps and / or portions thereof, or elements. FIG. 9B and the disclosure illustrating the steps of the method 370 described herein do not necessarily dictate the order in which these steps are performed. Rather, while one example order is shown, it should be understood that the order of these steps can be changed as appropriate. Thus, some of the steps can be performed in a different order or simultaneously.

[0139] 9B, the method 370 includes the step 372 of placing a composite laminate blank 14b between and in contact with a female die 54a and a male die 64a of the highly contoured stringer forming apparatus 10a, as described in detail above. The composite laminate blank 14b is initially placed in the female die 54a, and the male die 64a is lowered toward the composite laminate blank 14b and the female die 54a until the male die 64a contacts the composite laminate blank 14b. Preferably, a taper 68, such as in the form of a punch 68a, contacts the second surface 51b of the cap portion 50a of the composite laminate blank 14b.

[0140] The female die 54a has multiple pairs 55 of die blocks 56a spaced apart to define a die cavity 58. The female die 54a further includes a restraint assembly 60, as described above, with a restraint device 62 disposed in the die cavity 58. The restraint device 62 is in contact with the first surface 51a of the cap portion 50a of the composite laminate blank 14b via a vacuum bag 105.

[0141] In step 372, the composite laminate molding material 14b is placed between and in contact with the female die 54a and the male die 64a, where the female die 54a has a restraining assembly 60 having a restraining device 62. In step 372, the composite laminate molding material 14b is placed between and in contact with the female die 54a and the male die 64a, where the female die 54a has a restraining assembly 60 which, in one embodiment, is a foam vacuum assembly 100 (see FIG. 1B) and a restraining device 62 which includes a compressible foam element 102 (see FIG. 1B).

[0142] 1B and as described above, the foam vacuum assembly 100 includes a compressible foam element 102, a vacuum bag 105 surrounding the compressible foam element 102, a vacuum source 106 coupled to the vacuum bag 105 via a vacuum line 108, and a control valve 110. The retaining element 96 of the restraining assembly 60 configures the vacuum bag 105 when the male die 64a retracts from the female die 54a. The vacuum bag 105 is designed to hold or press the compressible foam element 102 in a pressed position 116a so that the compressible foam element 102 can expand back to the expanded position 112a and prevent the highly contoured composite structure 18 from moving upward unnecessarily. A vacuum pressure 118 or vacuum is applied to the compressible foam element 102, and the vacuum bag 105 maintains and holds the compressible foam element 102 in the pressed position 116a until the highly contoured composite structure 18 is removed from the female die 54a. Once the highly contoured composite structure 18 is removed from the female die 54a, the vacuum pressure 118, or vacuum, is turned off or released, allowing the compressible foam element 102 to expand and return to the expanded position 112a.

[0143] As discussed above, the compressible foam element 102 is a single-use compressible foam element 102a that is removed from the female die 54a of a molding apparatus 10, such as the highly contoured stringer molding apparatus 10a, after it has been used in a single molding process 12. Alternatively, the compressible foam element 102 may be a multiple-use compressible foam element 102b that is designed to remain in the female die 54a of a molding apparatus 10, such as the highly contoured stringer molding apparatus 10a, and can be used in multiple molding processes 12 in the molding apparatus 10. The compressible foam element 102 may be removably connected to the female die 54a to facilitate removal of the compressible foam element 102 for cleaning or repair, or to facilitate removal of the compressible foam element 102 for replacement with an unused or new compressible foam element.

[0144] The compressible foam element 102 includes a compressible foam material 122. As shown in FIG. 1B and as described above, the compressible foam material 122 may include an open cell foam 124, such as polyurethane foam 124a, latex rubber foam 124b, or other suitable open cell foam. Preferably, the open cell foam 124 has a compressible strength of 3 lb / ft 3 (3 pounds / cubic foot) ~ 13 lb / ft 3 The foam is in the form of a high density foam 126a (see FIG. 1B) having a density 128a (see FIG. 1B) in the range of 13 pounds per cubic foot.

[0145] 1B, the compressible foam material 122 may also include a closed cell foam 130, such as a polyethylene foam 130a, such as an expanded polyethylene foam, a polystyrene foam 130b, such as an expanded polystyrene foam, a polypropylene foam 130c, such as an expanded polypropylene foam, a neoprene foam rubber 130d, or other suitable closed cell foam. Preferably, the closed cell foam 130 has a foam strength of 2 lb / ft 3 (2 pounds / cubic foot)~10 lb / ft 3 1B) having a density 128b (see FIG. 1B) in the range of 10 (10 pounds per cubic foot).

[0146] The densities 128a, 128b selected for the compressible foam material 122 of the compressible foam element 102 are determined by the type of composite molding feedstock 14 used and the type of contoured composite structure 16, such as the highly contoured composite structure 18, or part being molded using the molding apparatus 10 and molding process 12.

[0147] In step 372 (see FIG. 9B), when the composite laminate molding material 14b is placed between and in contact with the female die 54a and the male die 64a, the female die 54a having a restraining assembly 60 having a restraining device 62, which in another embodiment is a pneumatic assembly 132 and a restraining device 62 including an air cylinder rod 134 having a cap presser 136.

[0148] As shown in FIG. 1B, pneumatic assembly 132 includes an air cylinder rod 134 having a cap presser 136, an air cylinder 146 coupled to air cylinder rod 134, and an air supply 158 coupled to air cylinder 146 via one or more air supply lines 154 and one or more ports 157.

[0149] In step 372 (see FIG. 9B), the composite laminate blank 14b is placed between and in contact with the female die 54a and the male die 64a, where the female die 54a has a restraining assembly 60 having a restraining device 62. The female die 54a has a restraining assembly 60 which is a spring assembly 184 and a restraining device 62 which includes a spring loaded plate 186. As shown in FIG. 1B, the spring assembly 184 includes the spring loaded plate 186 which includes a spring element 190 (see FIG. 7B), a stabilizing rod 192 (see FIG. 7B), and a cap presser 194 (see FIG. 7B).

[0150] As shown in Figure 1A, a forming apparatus 10, such as the highly contoured stringer forming apparatus 10a, further includes a control system 70 that operatively controls operation 72 of the highly contoured stringer forming apparatus 10a, in controlling the movement and motion of the female die 54a and male die 64a in coordination with the movement and motion of the restraint assembly 60. Control system 70 is described in detail above in connection with Figure 1A.

[0151] As shown in Figure 9B, the method 370 further includes forcing 374 the composite laminate blank 14b into the die cavity 58 of the highly contoured stringer forming apparatus 10a to form the contoured hat portion 43 of the aircraft stringer 34b. As shown in Figure 3A, the contoured hat portion 43 includes a cap 50 and a side portion 256. The contoured hat portion 43 may further include a flange 262 (see Figure 3A).

[0152] 9B, the method 370 further includes a step 376 of using the restraining device 62 to restrain the cap 50 between the restraining device 62 and the male die 64a as the contoured hat portion 43 is formed, and using the restraining device 62 to exert an upward resistance force 92 against the cap 50 and against the downward pushing force 90 exerted by the male die 64a to steer stress away from the cap 50 and achieve wrinkle prevention 44 to prevent wrinkle formation or fiber distortion in the cap 50. The restraining device 62 achieves a stress transfer 49 (see FIG. 1B) that steers stress away from the cap portion 50a, and thus the cap 50, to one or more remaining portions 50b of the composite molded feedstock 14, such as the remaining portion 50b that is molded as the flange 262 (see FIG. 4).

[0153] Step 376 of restraining the cap 52 using the restraining device 62 and applying an upward resistance force 92 as the contoured hat portion 43 is formed may further include applying an upward resistance force 92 in a range of 10 pounds per square inch (psi) to 200 psi. Step 456 of restraining the cap 52 using the restraining device 62 and applying an upward resistance force 92 against the downward force 90 applied by the male die 64a as the contoured hat portion 43 is formed may further include applying a downward force 90 in a range of 20 pounds per square inch (psi) to 380 psi.

[0154] As the contoured hat portion 43 is formed, step 376 of restraining the cap 52 using the restraining device 62 and applying an upward resistance force 92 against the downward pressing force 90 applied by the male die 64a may further include the downward pressing force 90 applied by the male die 64a pressing down on the cap 50, pressing down on the restraining device 62, and causing one or more of the pairs 55 of die blocks 56a, such as the left die block 56b (see FIG. 8) and the right die block 56c (see FIG. 8), to move laterally outward.

[0155] As shown in FIG. 9B, the method 370 further includes forming 378 the remaining portion 50b of the composite laminate blank 14b (see FIG. 1A) into an aircraft stringer 34b while the restraining device 62 continues to apply an upward resistance force 92 against the cap 50 and against the downward pushing force 90 while restraining the cap 50.

[0156] As shown in Figure 9B, the method 370 further includes a step 380 of forming the aircraft stringer 34b having the cap 50 in a fiber distortion- and wrinkle-free state 46. As shown in Figure 9B, the method 370 further includes a step 382 of retracting the male die 64a from the aircraft stringer 34b. As shown in Figure 9B, the method 370 further includes a step 384 of holding the restraining device 62 using a retention element 96 of the restraining assembly 60 to prevent the restraining device 62 from pushing up the aircraft stringer 34b as the male die 64a is retracted.

[0157] As described above, when the restraint assembly 60 is a foam vacuum assembly 100, the retaining element 96 preferably includes a vacuum bag 105 to which a vacuum pressure 118 (see FIG. 1B) is applied, the vacuum bag surrounding the compressible foam element 102 and designed to maintain or hold the compressible foam element 102 in a compressed position 116a.

[0158] As mentioned above, when the restraining assembly 60 is a pneumatic assembly 132, in one embodiment the retaining element 96 may utilize a spring return 168 (see FIG. 1B) and a spring force 170 (see FIG. 1B) applied to the pneumatic cylinder rod 134 to hold the pneumatic cylinder rod 134 in the depressed position 116b (see FIG. 1B), and the pneumatic cylinder 146 is a single acting spring return pneumatic cylinder 146a (see FIG. 1B). When the restraining assembly 60 is a pneumatic assembly 132, in another embodiment the retaining element 96 may utilize an air pressure application 162b (see FIG. 1B) applied to the pneumatic cylinder rod 134 to hold the pneumatic cylinder rod 134 in the depressed position 116b, and the pneumatic cylinder 146 is a double acting pneumatic cylinder 146b (see FIG. 1B). In another embodiment, when the restraint assembly 60 is a pneumatic assembly 132, the retaining element 96 may include an actuating rod locking device 176 (see FIG. 1B) that holds the air cylinder rod 134 in the pressed position 116b, and the air cylinder 146 is a rod locking air cylinder 146c (see FIG. 1B).

[0159] As described above, when the restraint assembly 60 is the spring assembly 184, the retaining element 96 includes an actuating locking device 188 (see FIG. 1B) coupled to the spring-loaded plate 186, which is designed to maintain or hold the spring-loaded plate 186 in the pressed position 116c (see FIG. 1B).

[0160] As shown in FIG. 9B, the method 370 further includes a step 386 of removing the aircraft stringer 34b from the female die 54a.

[0161] 9B, the method 370 further includes a step 388 of releasing the retention element 96. The step 388 of releasing the retention element 96 preferably includes moving the restraining device 62 upwardly from the depressed position 116 to the extended position 112.

[0162] As shown in FIG. 9B , the method 370 may optionally further include, after removing 386 the aircraft stringer 34b from the female die 54a, transferring 390 the aircraft stringer 34b to one of a secondary holding tool 246, such as a curing tool, a substrate 248, such as an uncured skin, or other suitable structure for holding the aircraft stringer 34b.

[0163] Optionally, the method 370 may further include, after the step 388 of releasing the retaining element 96, moving one or more pairs 55 of die blocks 56a, such as the left die block 56b (see FIG. 8) and the right die block 56c (see FIG. 8), laterally inwardly back to their original positions.

[0164] 10A-17B, which illustrate various steps of an exemplary molding process 12 (see FIG. 1A) in which a molding apparatus 10 (see FIG. 1A) and molding process 12 (see FIG. 1A) of the present disclosure are used to form a highly contoured composite structure 18 (see FIG. 14A), such as a stringer 34 (see FIG. 14A), e.g., a hat-shaped stringer 34a (see FIG. 14A).

[0165] 10A and 10B, Fig. 10A is a schematic diagram of a pre-molding step 282 prior to molding cycle 12b (see Fig. 11A) showing an exemplary embodiment of a molding apparatus 10 of the present disclosure from a front view with first die 54 and second die 64 in an open position 222, the molding apparatus having a constraining assembly 60 in the form of a foaming vacuum assembly 100 with a constraining device 62 in the form of a compressible foam element 102. Fig. 10B is a schematic diagram of the molding apparatus 10 shown in Fig. 10A from a side view during pre-molding step 282 with a constraining device 62 in the form of a compressible foam element 102.

[0166] FIG 10B illustrates a composite molding blank 14, such as flat composite molding blank 14a, disposed in a first die 54 and spaced apart from a second die 64. In FIG 10A, a first die portion 56, such as die block 56a, specifically left die block 56b and right die block 56c, is in a first position 284 adjacent or substantially adjacent a constraining device 62, such as a compressible foam element 102, disposed in a die cavity 58 of the first die 54. A constraining device 62, such as a compressible foam element 102 (see FIGS. 10A and 10B), is covered or surrounded by a vacuum bag 105 (see FIGS. 10A and 10B), and the constraining device 62, such as a compressible foam element 102, is in an extended position 112 (see FIG. 10B), such as a fully extended position, such as an extended position 112a (see FIG. 10B). As shown in FIG. 10B, a first end 103a, or upper end, of compressible foam element 102 engages first surface 51a of cap portion 50a of composite molding blank 14 via vacuum bag 105. As shown in FIG.

[0167] 10A and 10B, and 11A-17B, further show the vacuum line 108, vacuum source 106, such as vacuum pump 106a, and control valve 110 of the foam vacuum assembly 100. The vacuum bag 105 is attached to the vacuum source 106 via the vacuum line 108, which incorporates the control valve 110. As shown in FIGS. 10A and 10B, and 11A-17B, the restraining device 62, such as a compressible foam element 102, which is covered or surrounded by the vacuum bag 105, is attached to the vacuum source 106, such as vacuum pump 106a, via the vacuum line 108 and control valve 110, all of which are included in the foam vacuum assembly 100. FIGS. 10A and 10B further show the molding apparatus 10 having a control system 70 with a controller 74. The control system 70 operatively controls the molding apparatus 10, in that it controls the operation of the first die 54 and the second die 64 in coordination with the operation of the restraint assembly 60. Although the control system 70 with the controller 74 is not shown in FIGS. 11A-17B, it will be understood from FIGS. 10A and 10B that the molding apparatus 10 shown in FIGS. 11A-17B is similarly coupled to the control system 70 with the controller 74 as shown in FIGS. 10A and 10B. Also shown in FIGS. 10A and 10B is the second die 64 including a tapered portion 68, such as a punch 68a. The tapered portion 68 has an engagement surface 286 designed to engage the second surface 51b of the cap portion 50a of the composite molding blank 14.

[0168] 11A and 11B, FIGURE 11A is a schematic diagram of a first molding step 288 of a molding cycle 12b showing a molding apparatus 10 having a constraining device 62 in the form of a compressible foam element 102 viewed from the front, a first die 54 and a second die 64 in a closed position 224, and consolidation 290 of a cap portion 50a of a composite molding blank 14, such as a flat composite molding blank 14a. FIGURE 11B is a schematic diagram of the molding apparatus 10 and the constraining device 62 in the form of a compressible foam element 102 shown in FIGURE 11A viewed from the side during the first molding step 288.

[0169] As shown in Figures 11A and 11B, when the tapered portion 68 of the second die 64 is lowered, the engagement surface 286 (see Figure 10A) first contacts the second surface 51b (see Figure 10A) of the cap portion 50a of the composite molding blank 14. The compressible foam element 102 is in an extended position 112a (see Figure 11B) in the die cavity 58 (see Figure 11A) adjacent the left die block 56b (see Figure 11A) and the right die block 56c (see Figure 11A). As shown in Figures 11A and 11B, the cap portion 50a is restrained or clamped between a restraining device 62, such as the compressible foam element 102, and the tapered portion 68 of the second die 64 to hold the cap portion 50a together. As the second die 64 exerts a downward pushing force 90 (see FIG. 11B), the compressible foam element 102 exerts an upward resisting force 92 (see FIG. 11B) to restrain or clamp the cap portion 50a of the composite molded material 14. FIG. 11A illustrates the initial consolidation 290 of the cap portion 50a of the composite molded material 14 in the first molding step 288.

[0170] As used herein, the terms "integrating" or "integrating" refer to the solidification or bonding of composite materials in the formation of one or more portions of a contoured composite structure, such as a highly contoured composite structure, by pressing or compressing one or more portions of a composite molding feedstock together under pressure and / or heat to connect and / or fuse individual plies of composite material and to cause resin and fibrous materials to flow or move.

[0171] 12A and 12B, Fig. 12A is a schematic diagram of a second molding step 292 of molding cycle 12b, showing the molding apparatus 10 and a constraining device 62 in the form of a compressible foam element 102 from a front view and showing a second die 64, such as the tapered portion 68 of the second die 64, partially inserted into the die cavity 58 of the first die 54 at a first insertion position 294. Fig. 12B is a schematic diagram of the molding apparatus 10 and the constraining device 62 in the form of a compressible foam element 102 shown in Fig. 12A from a side view during the second molding step 292.

[0172] 12A, during a second molding step 292 during molding cycle 12b, tapered portion 68 of second die 64 is partially inserted, pressed, or forced into die cavity 58 of first die 54 to push left die block 56b and right die block 56c apart and move laterally outwardly to a second position 296. Left die block 56b is moved laterally outwardly in a first lateral direction 274 (see FIG. 12A), and right die block 56c is moved laterally outwardly in a second lateral direction 276 (see FIG. 12A). As the left and right die blocks 56b, 56c move laterally outward, a first space 298 (see FIG. 12A) is formed on either side of the compressible foam element 102, specifically between the compressible foam element 102, which is covered or surrounded by the vacuum bag 105, and each of the left and right die blocks 56b, 56c.

[0173] 12A and 12B, the cap portion 50a continues to be constrained or clamped by a constraining device 62, such as a compressible foam element 102, between the second die 64 and the constraining device 62. As the second die 64 continues to apply a downward pushing force 90 (see FIG. 12B), the compressible foam element 102 continues to apply an upward resisting force 92 (see FIG. 12B) to constrain or clamp the cap portion 50a of the composite molded material 14. The cap portion 50a continues to be consolidated 290 (see FIGS. 12A and 12B) by the constraining device 62 to form the cap 52 (see FIG. 14A) of the contoured hat portion 43 (see FIG. 13A). A restraining device 62, such as a compressible foam element 102, is in the die cavity 58 (FIG. 12A) between the left die block 56b and the right die block 56c at an intermediate press position 114 (see FIG. 12B), such as intermediate press position 114b (see FIG. 12B).

[0174] 13A and 13B, Fig. 13A is a schematic diagram of a third molding step 300 of molding cycle 12b, showing the molding apparatus 10 and the constraining device 62 in the form of a compressible foam element 102 from a front view, with the second die 64 fully inserted into the die cavity 58 of the first die 54 at a second insertion position 302. Fig. 13B is a schematic diagram of the molding apparatus 10 and the constraining device 62 in the form of a compressible foam element 102 from a side view shown in Fig. 13A, during the third molding step 300.

[0175] 13A, in a third forming step 300, the tapered portion 68 (see FIG. 13B) of the second die 64 is fully inserted, pressed, or forced into the die cavity 58 of the first die 54 to a second insertion position 302, further pushing the left and right die blocks 56b, 56c apart and moving the left and right die blocks 56b, 56c further laterally outward to a third position 304. The left die block 56b is further moved laterally outward in a first lateral direction 274 (see FIG. 13A), and the right die block 56c is further moved laterally outward in a second lateral direction 276 (see FIG. 13A). As the left and right die blocks 56b, 56c move further laterally outward, second spaces 306 (see FIG. 13A) are formed on either side of the compressible foam element 102, specifically between the compressible foam element 102, which is covered or surrounded by the vacuum bag 105, and the left and right die blocks 56b, 56c, respectively.

[0176] As shown in Figures 13A and 13B, the cap 52 formed by the cap portion 50a (see Figure 11A) is constrained or clamped by a constraining device 62, such as a compressible foam element 102, between the second die 64 and the constraining device 62. As the second die 64 continues to apply a downward pushing force 90 (see Figure 13B), the compressible foam element 102 continues to apply an upward resisting force 92 (see Figure 13B) to constrain or clamp the cap 52 of the contoured hat portion 43 being formed. The remaining portion 50b (see Figure 13A) of the cap portion 50a is integrated 290 (see Figure 13A) to form the sides 260 (see Figure 14A) and flange 262 (see Figure 14A) of the contoured hat portion 43. A restraining device 62 (see FIG. 13B), such as a compressible foam element 102 (see FIG. 13B), is in a pressing position 116 (see FIG. 13B), such as pressing position 116a (see FIG. 13B), in the die cavity 58 (see FIG. 13A) between the left die block 56b (see FIG. 13A) and the right die block 56c (see FIG. 13A). In the third molding step, molding cycle 12b is completed.

[0177] 14A and 14B, Fig. 14A is a schematic diagram of the post-molding vacuum application step 308 showing the molding apparatus 10 and the constraining device 62 in the form of a compressible foam element 102 from a front view, with the second die 64 retracted after application of vacuum and the first and second dies in the open position 222. Fig. 14B is a schematic diagram of the molding apparatus 10 and the constraining device 62 in the form of a compressible foam element 102 from a side view shown in Fig. 14A during the post-molding vacuum application step 308.

[0178] As shown in Figure 14A, after molding cycle 12b (see Figure 13A) is completed, a highly contoured composite structure 18, such as a stringer 34, e.g., a hat-shaped stringer 34a, is obtained. As shown in Figure 14A, the highly contoured composite structure 18, such as a stringer 34, e.g., a hat-shaped stringer 34a, includes a cap 52, a side 260, and a flange 262.

[0179] In a post-molding vacuum application step 308, before the second die 64 retracts from the first die 54 and from the highly contoured composite structure 18, such as a stringer 34, e.g., hat-shaped stringer 34a, a vacuum, such as vacuum pressure 118 (see FIG. 1B), is applied from a vacuum source 106 (see FIG. 10A), such as a vacuum pump 106a (see FIG. 10A), to a vacuum bag 105 (see FIG. 14B) and the compressible foam element 102 surrounded by the vacuum bag 105. A control valve 110 (see FIG. 10A) is opened to turn on the vacuum pressure 118 from the vacuum source 106 and to control the rate at which air is removed from the vacuum bag 105 surrounding the compressible foam element 102. Air is drawn or sucked out of the vacuum bag 105 via the vacuum line 108 and vacuum source 106 to compress the vacuum bag 105 around the compressible foam element 102 to hold and maintain the compressible foam element 102 in a pressed position 116a, such as a fully pressed position. The vacuum bag 105 surrounding the compressible foam element 102 under vacuum pressure 118 is designed to act as a retaining element 96 (see FIG. 1B) to hold the compressible foam element 102 in the pressed position 116a to prevent the restraining device 62, such as the compressible foam element 102, from pushing up the highly contoured composite structure 18, such as the stringer 34, e.g., hat-shaped stringer 34a, as the second die 64 retracts. As shown in FIG. 14A, the restraining device 62, such as the compressible foam element 102, is in the pressed position 116a in the die cavity 58 between the left die block 56b and the right die block 56c.

[0180] 15A and 15B, Fig. 15A is a schematic diagram of a shaped stringer removal step 310 showing the molding apparatus 10 and a restraining device 62 in the form of a compressible foam element 102 from a front view, with the molded stringer 34 (see Fig. 14A) having been removed from the first die 54. Fig. 15B is a schematic diagram of the molding apparatus 10 and a restraining device 62 in the form of a compressible foam element 102 from a side view shown in Fig. 15A, during the shaped stringer removal step 310.

[0181] In a formed stringer removal step 310, the highly contoured composite structure 18 (see FIG. 14A), such as a stringer 34 (see FIG. 14A), e.g., a hat-shaped stringer 34a (see FIG. 14A), is removed from the first die 54 (see FIG. 15A) and a vacuum, such as a vacuum pressure 118, is maintained by a vacuum source 106 (see FIG. 10A), such as a vacuum pump 106a (see FIG. 10A), against a vacuum bag (see FIGS. 15A and 15B) and a restraining device 62, such as a compressible foam element 102, surrounded by the vacuum bag 105. As shown in FIGS. 15A and 15B, the restraining device 62, such as a compressible foam element 102, is in a pressing position 116a in the die cavity 58 between the left die block 56b and the right die block 56c. As shown in FIG. 15A, left die block 56b and right die block 56c are still in third position 304 and second die 64 is still in a retracted position.

[0182] 16A and 16B, Fig. 16A is a schematic diagram of a vacuum releasing step 312 showing a molding apparatus 10 and a constraining device 62 in the form of a compressible foam element 102 from a front view and showing the release of a vacuum, such as vacuum pressure 118, from a constraining device 62, such as a vacuum bag 105 and a compressible foam element 102 enclosed within the vacuum bag 105. Fig. 16B is a schematic diagram of a side view of the molding apparatus 10 and a constraining device 62 in the form of a compressible foam element 102 during the vacuum releasing step 312.

[0183] In a release vacuum step 312, the control valve 110 (see FIG. 10A) is closed and the vacuum source 106 (see FIG. 10A), such as vacuum pump 106a (see FIG. 10), is turned off to release the vacuum, such as vacuum pressure 118, from the vacuum bag 105 and the constraining device 62, such as the compressible foam element 102, enclosed within the vacuum bag 105. This allows the constraining device 62, such as the compressible foam element 102, to re-expand to its original position, such as an extended position 112a (see FIG. 16A), such as a fully extended position, while still surrounded by the vacuum bag 105. As shown in FIG. 16A, the left die block 56b and the right die block 56c are still in the third position 304 and the second die 64 is still in a retracted position.

[0184] 17A and 17B, Fig. 17A is a schematic diagram of a first die return step 314 showing the molding apparatus 10 and the constraining device 62 in the form of the compressible foam element 102 from a front view and showing the first die 54, such as left die block 56b and right die block 56c, returning to an original position, such as first position 284. Fig. 17B is a schematic diagram of the molding apparatus 10, the constraining device 62 in the form of the compressible foam element 102, and the constraining assembly from Fig. 17A from a side view during the first die return step 314.

[0185] In a first die return step 314, the control system 70 (see FIG. 1A) of the molding apparatus 10 controls the operation of the left and right die blocks 56b, 56c and operates the controllers to return the left and right die blocks 56b, 56c to their original positions, i.e., first position 284, after the highly contoured composite structure 18 (see FIG. 14A), such as the stringer 34 (see FIG. 14A), e.g., hat-shaped stringer 34a (see FIG. 14A), is removed from the first die 54 and after the vacuum, such as the vacuum pressure 118, is turned off. In FIG. 17A, the compressible foam element 102 is shown expanding back to the expanded position 112a.

[0186] Figure 18 is a front perspective view of an exemplary embodiment of a secondary holding tool 246 for holding a contoured composite structure 16 (see Figure 1A), such as highly contoured composite structure 18 (see Figure 1A), after the contoured composite structure 16 has been formed in molding process 12 using molding apparatus 10 of the present disclosure. As shown in Figure 18, a contoured composite structure 16 (see Figures 1A and 4), such as highly contoured composite structure 18 (see Figures 1A and 4), may be placed and held on tool surface 247, for example, for curing, finishing, or other suitable processing or assembly operations.

[0187] 19, which is a perspective view of an air vehicle 400, such as an aircraft 400a, incorporating a highly contoured composite structure 18, such as in the form of an aircraft stringer 34b, that is fabricated using an embodiment of a forming apparatus 10 (see FIGS. 1A, 2A-2B, and 3), such as a highly contoured stringer forming apparatus 10a (see FIGS. 1A, 2A-2B, and 3) of the present disclosure, and a forming process 12. As shown in FIG. 19, the air vehicle 400, such as the aircraft 400a, includes a fuselage 402, a nose 404, wings 406, an engine 408, and a tail section 410. As shown in FIG. 19, the tail section 410 includes a vertical stabilizer 412 and a horizontal stabilizer 414.

[0188] Contoured composite structures 16 (see FIGS. 1A and 4), such as highly contoured composite structure 18 (see FIGS. 1A and 4), may be used individually or in combination with other structures or devices. As shown in FIG. 19, in one embodiment, once the highly contoured composite structure 18 including the aircraft stringers 34b is formed, it may be used for a portion of the fuselage 402 of the aircraft 400a. For example, before or after curing each of the highly contoured composite structures 18 including the aircraft stringers 34b, the highly contoured composite structures may be placed on a mandrel of a machine to create a portion of the fuselage 402. A fiber reinforced resin may be applied onto the highly contoured composite structures 18 including the aircraft stringers 34b, and then the fiber reinforced resin may be cured (or cured with other structures) to create the completed assembly for the fuselage 402 of the aircraft 400a. After forming the highly contoured composite structure 18, such as in the form of an aircraft stringer 34b, the highly contoured composite structure may be used as a portion of a wing 406, a vertical stabilizer 412, a horizontal stabilizer 414, or other suitable component of an aircraft 400a. The highly contoured composite structure 18 may be used in a variety of industries and applications related to, but not limited to, the manufacture of aircraft 400a, other aerospace structures and vehicles, including spacecraft and rotorcraft, and the manufacture of vehicles, such as ships, trains, and other suitable vehicles or structures.

[0189] 20 and 21, FIG. 20 is a flow diagram illustrating an exemplary aircraft manufacturing and service method 450, and FIG. 21 is an exemplary block diagram illustrating an aircraft 466. With reference to FIG. 20 and FIG. 21, embodiments of the present disclosure will be described with reference to the aircraft manufacturing and service method 450 illustrated in FIG. 20 and with reference to the aircraft 466 illustrated in FIG.

[0190] As a pre-production step, the exemplary aircraft manufacturing and service method 450 may include specification and design 452 of the aircraft 466 and material procurement 454. During production, component and subassembly manufacturing 456 and system integration 458 of the aircraft 466 occurs. The aircraft 466 then goes through certification and delivery 460 before entering service 462. While in customer service 462, the aircraft 466 undergoes routine maintenance and service 464 (which may include modifications, reconfigurations, refurbishments, and other suitable maintenance).

[0191] Each step of aircraft manufacturing and service method 450 may be performed or carried out by a system integrator, a third party, and / or an operator (e.g., a customer). As used herein, a system integrator may include, but is not limited to, the aircraft manufacturer and any number of major system subcontractors. A third party may include, but is not limited to, any number of vendors, subcontractors, and suppliers. An operator may be an airline, a leasing company, a military entity, a service organization, etc., or any other suitable operator.

[0192] 21 , an aircraft 466 produced by exemplary aircraft manufacturing and service method 450 may include an airframe 468 having a number of systems 470 and an interior 472. Examples of the number of systems 470 include one or more of a propulsion system 474, an electrical system 476, a hydraulic system 478, and an environmental system 480, as well as any number of other systems. Although illustrated in the aerospace industry, the principles of the present disclosure may be applied to other industries, such as the automotive industry.

[0193] The methods and systems specifically illustrated herein may be employed during any one or more stages of aircraft manufacturing and service method 450. For example, the parts or subassemblies corresponding to part and subassembly manufacturing 456 may be manufactured in a manner similar to the parts or subassemblies manufactured during in service 462 of aircraft 466. Also, one or more apparatus embodiments, method embodiments, or combinations thereof may be used during part and subassembly manufacturing 456 and system integration 458 to substantially speed up or reduce the cost of assembly of aircraft 466. Similarly, one or more apparatus embodiments, method embodiments, or combinations thereof may be used during in service 462 of aircraft 466, such as, but not limited to, maintenance and service 464.

[0194] The disclosed embodiments of forming apparatus 10 (see FIGS. 1, 2A-2B, and 3), such as highly contoured stringer forming apparatus 10a (see FIGS. 1, 2A-2B, and 3), method 350 (see FIG. 9A), and method 370 (see FIG. 9B), provide an automated forming apparatus 10b (see FIGS. 1, 2A-2B) using an automated forming process 12a (see FIG. 1A) that can reduce labor and time compared to hand layup techniques. Known hand layup techniques can take approximately eight times longer to form a contoured composite structure compared to the forming process 12 using the forming apparatus 10 of the present disclosure. Additionally, embodiments of the present disclosure for forming apparatus 10 (see FIGS. 1, 2A-2B, and 3), such as highly contoured stringer forming apparatus 10a (see FIGS. 1, 2A-2B, and 3), method 350 (see FIG. 9A), and method 370 (see FIG. 9B) can increase production rates of contoured composite structures 16 (see FIGS. 1A and 4), such as highly contoured composite structure 18 (see FIGS. 1A and 4), and avoid costs associated with additional inspection and correction of wrinkles or fiber distortions in known methods. Additionally, embodiments of the present disclosure for forming apparatus 10 (see FIGS. 1, 2A-2B, and 3), such as highly contoured stringer forming apparatus 10a (see FIGS. 1, 2A-2B, and 3), method 350 (see FIG. 9A), and method 370 (see FIG. 9B), may enable contoured composite structures 16 (see FIGS. 1A and 4), such as highly contoured composite structure 18 (see FIGS. 1A and 4), to be designed with complex contours 30a (see FIG. 1A), with highly contoured contours having contour radii 98 (see FIG. 1A) that are smaller than the contour radii of contoured structures formed by known methods, thereby producing more efficient aircraft 400a (see FIG. 19) and other aerospace vehicles or structures.Embodiments of the present disclosure for forming apparatus 10 (see FIGS. 1, 2A-2B, and 3), such as highly contoured stringer forming apparatus 10a (see FIGS. 1, 2A-2B, and 3), method 350 (see FIG. 9A), and method 370 (see FIG. 9B) can vary the thickness or depth of a formed part, for example a contoured composite structure 16 (see FIGS. 1A and 4), such as a molded highly contoured composite structure 18 (see FIGS. 1A and 4), without creating a unique die for each part.

[0195] Additionally, embodiments of the present disclosure for a forming apparatus 10 (see FIGS. 1, 2A-2B, and 3), such as highly contoured stringer forming apparatus 10a (see FIGS. 1, 2A-2B, and 3), method 350 (see FIG. 9A), and method 370 (see FIG. 9B) can improve the forming process 12 (see FIG. 1A) of a contoured composite structure 16 (see FIGS. 1A and 4), such as highly contoured composite structure 18 (see FIGS. 1A and 4), for example, an aircraft stringer 34b (see FIGS. 1A and 19), such as fuselage stringer 34d (see FIG. 1A), by adding a restraining assembly 60 (see FIG. 1B) having a restraining device 62 (see FIG. 1B). The restraining device 62 (see FIG. 1B) restrains a cap portion 50a (see FIGS. 8 and 11A) of a composite molding blank 14 (see FIGS. 8 and 11A) prior to the forming process 12 (see FIG. 1A). The restraining device 62 also restrains the cap portion 50a, or the cap 52 (see FIG. 13A) formed from the cap portion 50a, when the contoured hat portion 43 (see FIG. 13A) is formed during the molding process 12. When the second die 64, or the upper die 64b (see FIG. 1A) applies a downward pressing force 90 (see FIG. 8), the restraining assembly, and in particular the restraining device 62, applies an upward resistance force 92 (see FIG. 8) to the cap portion 50a or cap 52 and against the downward pressing force 90 (see FIG. 8) applied by the second die 64 (see FIG. 8), thereby relieving stress from the cap portion 50a or cap 52 and achieving wrinkle prevention 44 (see FIG. 1A) or wrinkle reduction 45 (see FIG. 1A) in the cap portion 50a or cap 52. This results in a contoured composite structure 16, such as a highly contoured composite structure 18, having a cap 52 in a wrinkle-free condition 46 (see FIG. 1A) or in a wrinkle-reduced condition 48 (see FIG. 1A). In particular, this restraining or clamping by the restraining device 62 can prevent or reduce wrinkles from forming in the cap 52 of the stringer 34 (see FIG. 1A) (see FIG. 1A). The molding apparatus 10 and molding process 12 using the restraining assembly 60, and particularly the restraining device 62, can eliminate or substantially eliminate wrinkles, fiber distortion, and the like.For example, whereas existing form-to-contour methods and technologies reduce wrinkles in contoured composite parts or caps of contoured composite structures by 75% or less, the molding apparatus 10 and molding process 12 using a restraining assembly 60 having a restraining device 62 as disclosed herein can eliminate wrinkles in the caps 52 of contoured composite structures 16, such as highly contoured composite structures 18, by 95% to 100%. However, the percentage of wrinkle elimination can vary depending on the contour, thickness, and other factors.

[0196] Additionally, the constraint assembly 60 (see FIG. 1B) advantageously includes a retention element 96 (see FIG. 1B) designed to regulate the motion of the constraint device 62 when the highly contoured composite structure 18 is formed and the second die 64 is retracted from the first die 54. The retention element 96 prevents the constraint device 62 from pushing up on the highly contoured composite structure 18 when the second die 64 is retracted from the first die 54. Preferably, the retention element 96 releases the upward resistive force 92 applied by the constraint device 62 when the second die 64, i.e., the upper die 64b, is retracted upward.

[0197] Many modifications and other aspects of the disclosure set forth herein will be predictable to one skilled in the art to which this disclosure pertains having the benefit of the teachings of the foregoing descriptions and the associated drawings. The embodiments described herein are illustrative and are not intended to be limiting or comprehensive. Although specific terms are employed herein, these terms are used in a generic and descriptive sense and not for purposes of limitation. In addition to the methods and apparatus recited herein, methods and apparatus that are functionally equivalent within the scope of the disclosure are possible from the above description. Such modifications and variations are intended to be within the scope of the appended claims. The disclosure is limited only by the terms of the appended claims, along with the full scope of equivalents that such claims are entitled to.

[0198] Furthermore, the present disclosure includes embodiments according to the following appendices.

[0199] Appendix 1. A method for forming an aircraft stringer having a wrinkle-free cap, comprising: placing a composite laminate material between and in contact with a female die and a male die of a highly contoured stringer forming apparatus, the female die having a pair of die blocks spaced apart from one another to define a die cavity, the female die having a restraining assembly having a restraining device disposed in the die cavity; forcing the composite laminate material into the die cavity of the highly contoured stringer forming apparatus to form a contoured hat portion of the aircraft stringer, the contoured hat portion having the cap and sides, and using the restraining device to restrain the cap as the contoured hat portion is formed, and using the restraining device to press the composite laminate material against the cap and ... applying an upward resistance force against a downward pressure applied by the male die to relieve stress from the cap and prevent wrinkles in the cap; molding a remainder of the composite laminate material into the aircraft stringer while the restraining device continues to apply the upward resistance force against the cap and against the downward pressure while restraining the cap to form the aircraft stringer with the cap without wrinkles; retracting the male die from the aircraft stringer; holding the restraining device using a retention element of the restraining assembly to prevent the restraining device from pushing up on the aircraft stringer as the male die retracts; removing the aircraft stringer from the female die; and releasing the retention element.

[0200] Clause 2. The method of clause 1, further comprising, after removing the aircraft stringer from the female die, transferring the aircraft stringer to one of a secondary holding tool and a substrate.

[0201] Appendix 3. The method of Appendix 1, wherein in the step of placing the composite laminate molding material between and in contact with the female die and the male die, wherein the female die has the restraint assembly having the restraint device, when placing the composite laminate molding material between and in contact with the female die and the male die, the female die has the restraint assembly which is a foam vacuum assembly and the restraint device which includes a compressible foam element.

[0202] Appendix 4. The method of appendix 1, wherein in the step of placing the composite laminate molding material between and in contact with the female die and the male die, wherein the female die has the restraint assembly having the restraint device, when placing the composite laminate molding material between and in contact with the female die and the male die, the female die has the restraint assembly which is a pneumatic assembly and the restraint device which includes an air cylinder rod with a cap presser.

[0203] Addendum 5. The method of Addendum 1, wherein in the step of placing the composite laminate molding material between and in contact with the female die and the male die, wherein the female die has the restraint assembly having the restraint device, when placing the composite laminate molding material between and in contact with the female die and the male die, the female die has the restraint assembly which is a spring assembly and the restraint device which includes a spring-loaded plate.

[0204] Addendum 6. The method of Addendum 1, wherein the step of constraining the cap using the constraining device and applying the upward force as the contoured hat portion is formed further includes applying the upward force in the range of 10 pounds per square inch (psi) to 200 psi.

[0205] Addendum 7. The method of Addendum 1, wherein the step of constraining the cap using the restraining device and applying the upward resistance force against the downward force applied by the male die as the contoured hat portion is formed further includes applying the downward force in the range of 20 pounds per square inch (psi) to 380 psi.

[0206] Appendix 8. The method of Appendix 1, wherein the step of constraining the cap using the constraining device and applying the upward resistance force against the downward force applied by the male die as the contoured hat portion is formed further includes the downward force depressing the cap, pressing against the constraining device, and moving one or more of the pair of die blocks laterally outward.

Claims

1. 1. A molding apparatus for constraining a composite feedstock and forming the composite feedstock into a highly contoured composite structure, comprising: A first die and a second die; a restraint assembly; the composite molding material is molded between the first die and the second die, the first die having a pair of first die portions spaced apart from one another to define a die cavity in which the composite molding material is molded into a contoured hat portion having a cap, the pair being slidably displaceable relative to one another, and the second die having a tapered portion designed to be at least partially inserted into the die cavity; the constraint assembly is coupled to the first die and includes a constraint device disposed in the die cavity, the constraint device designed to constrain a cap portion of the composite molding material between the constraint device and the second die, the constraint device also designed to prevent wrinkles in the cap by exerting an upward resistance force on the cap portion and against a downward pushing force exerted by the second die when the contoured hat portion is formed, the constraint assembly further includes a retention element designed to retain the constraint device when the second die retracts after the highly contoured composite structure is formed.

2. 10. The molding apparatus of claim 1, further comprising a control system operatively controlling the molding apparatus, wherein the control system controls the operation of the first die and the second die in coordination with the operation of the constraint assembly.

3. 3. The forming apparatus of claim 1 or 2, wherein the highly contoured composite structure comprises one or more of a stringer, a hat stringer, an aircraft stringer, a hat aircraft stringer, a fuselage stringer, a keel stringer, a wing stringer, a stabilizer stringer, a stiffening member, a hat stiffening member, and a wing spar.

4. 4. The molding apparatus of claim 1, wherein the restraining device has a first end that directly or indirectly engages a first surface of the cap portion to apply the upward resistance force against the first surface of the cap portion and against the downward pushing force applied by the second die, thereby clamping the cap portion between the tapered portion of the second die and the first end during forming of the composite molding material into the highly contoured composite structure.

5. 5. The molding apparatus of claim 1, wherein the restraining device is initially in an extended position in the die cavity to restrain the cap portion against the second die during molding of the composite molding material into the highly contoured composite structure, and when the tapered portion of the second die is fully inserted into the die cavity, the restraining device is disposed in a pressing position and one or more of the pair of first die portions are positioned laterally outward from the restraining device.

6. The molding apparatus of any preceding claim, wherein the constraining assembly comprises a foam vacuum assembly and the constraining device comprises a compressible foam element.

7. 7. The molding apparatus of claim 6, wherein the foam vacuum assembly includes the compressible foam element, a vacuum bag surrounding the compressible foam element, a vacuum source coupled to the vacuum bag via a vacuum line, and one or more control valves.

8. 8. The molding apparatus of claim 7, wherein the holding element comprises a vacuum bag to which a vacuum pressure is applied, the vacuum bag surrounding the compressible foam element and designed to hold the compressible foam element in a compressed position.

9. The molding apparatus of any one of claims 1 to 8, wherein the restraining assembly includes a pneumatic assembly and the restraining device includes an air cylinder rod having a cap presser.

10. 10. The molding apparatus of claim 9, wherein the pneumatic assembly includes an air cylinder rod having the cap presser, an air cylinder coupled to the air cylinder rod, and an air supply coupled to the air cylinder via one or more air supply lines and one or more ports.

11. The retaining element comprises: utilizing a spring return and a spring force applied to the air cylinder rod to hold the air cylinder rod in a pressed position, the air cylinder being a single acting spring return air cylinder; applying air pressure to the air cylinder rod to hold the air cylinder rod in the pressed position, the air cylinder being a double acting air cylinder; and 11. The molding apparatus of claim 10, comprising one of: an actuating rod locking device that holds the air cylinder rod in the pressed position, the air cylinder being a rod locking air cylinder.

12. A molding apparatus according to any preceding claim, wherein the restraining assembly comprises a spring assembly and the restraining device comprises a spring loaded plate.

13. 13. The molding apparatus of claim 12, wherein the spring assembly includes the spring loaded plate and an actuation locking device coupled to the spring loaded plate, the spring loaded plate including a spring element, a stabilizing rod, and a cap presser.

14. 14. The molding device according to claim 13, wherein the holding element comprises an actuating locking device which is coupled to the spring-loaded plate and which is designed to hold the spring-loaded plate in a pressed position.

15. 1. A method for constraining a composite molding feedstock and forming the composite molding feedstock into a highly contoured composite structure, comprising: disposing the composite molding material between and in contact with a first die and a second die of a molding apparatus, the first die having a pair of first die blocks spaced apart from one another to define a die cavity, the first die having a restraint assembly including a restraint device disposed in the die cavity; forcing the composite molding material into the die cavity of the molding apparatus to form a contoured hat portion having a cap and sides; using the restraining device to restrain the cap as the contoured hat portion is formed and using the restraining device to exert an upward resisting force on the cap and against a downward force exerted by the second die to relieve stress from the cap and prevent wrinkles in the cap; forming said highly contoured composite structure having said wrinkle-free cap; retaining the constraining device using a retention element of the constraining assembly to prevent the constraining device from pushing up against the highly contoured composite structure as the second die retracts.

16. After holding the restraining device, removing the highly contoured composite structure from the first die; 16. The method of claim 15, further comprising releasing the retaining element to move the restraining device upwardly from a compressed position to an extended position.

17. 20. The method of claim 16, further comprising, after removing the highly contoured composite structure from the first die, transferring the highly contoured composite structure to one of a secondary holding tool and a substrate.

18. 18. The method of claim 15, wherein in the step of disposing the composite molding material between and in contact with the first die and the second die, the first die has the constraining assembly being a foam vacuum assembly and the constraining device being a compressible foam element.

19. 19. The method according to claim 15, wherein in the step of placing the composite molding material between and in contact with the first die and the second die, the first die has the restraining assembly being a pneumatic assembly, and the restraining device including an air cylinder rod with a cap presser.

20. 20. The method of claim 15, wherein in the step of placing the composite molding material between and in contact with the first die and the second die, the first die has the constraint assembly being a spring assembly and the constraint device including a spring-loaded plate.

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