Tooling and method for forming a corrugation-reduced wave composite stringer

Abstract

The present disclosure relates to tools and methods for forming corrugation-reduced wavy composite stringers. A tool for manufacturing wavy composite hat stringers enables controlled stringer corrugation. The tool includes a set of first openings that enable the tool to bend during stringer formation of a wave, and a set of second openings into which portions of a composite charge can be strained during shaping of the wave.

Description

Technical Field

[0001] This disclosure generally relates to the manufacture of corrugated composite stringers, and more specifically, to tools and methods for manufacturing such stringers with reduced wrinkling. Background Technology

[0002] One technique for manufacturing composite stringers involves using a punch with a stringer shape to form a flat composite charge into a die. Some composite stringers have one or more corrugated segments along their length. To manufacture these corrugated segments, the stringer is shaped into the desired corrugation in a secondary forming operation. The operation of corrugating the stringer causes stress concentration along the inner radius of the stringer within the corrugated segments. These stress concentrations can cause wrinkles large enough to affect the stringer's performance to form within it. In some cases, the stringer is reworked to reduce the wrinkles to an acceptable level, while in other cases, the stringer may have to be discarded. Stringer rework increases labor costs, while discarding a stringer due to excessive wrinkling increases material costs.

[0003] Therefore, it is desirable to provide tools and methods for manufacturing corrugated composite stringers with reduced wrinkling levels to an acceptable level. Summary of the Invention

[0004] This disclosure generally relates to methods and apparatus for manufacturing composite stringers, and more specifically, to tools and methods for manufacturing corrugated composite stringers with reduced wrinkling.

[0005] According to one aspect, a tool for forming composite filler into a corrugated composite stringer is provided. The tool includes a tool body that is flexible and has length. The tool body includes a set of laterally extending first openings configured to allow the tool body to bend during the forming of the composite filler. The tool body also includes a set of laterally extending second openings into which portions of the composite filler can strain during forming.

[0006] According to another aspect, a tool is provided for shaping a composite filler into a corrugated stringer having a desired cross-sectional shape. The tool includes a punch configured to shape the composite filler into a shaped stringer having the desired cross-sectional shape and to cause the shaped stringer to form a corrugation along its length. The punch includes an opening into which the composite filler can strain as the shaped stringer is forming a corrugation along its length.

[0007] According to another aspect, a method for manufacturing a corrugated composite stringer with reduced wrinkling is provided. The method includes shaping a flat composite material into a desired cross-sectional shape using a tool, and forming the stringer into a corrugation, which includes bending the tool. The method includes using a first set of openings in the tool to enable the tool to bend into the desired corrugation, and using a second set of openings in the tool to alleviate stress in the composite material during shaping by enabling portions of the composite material to strain into the second set of openings.

[0008] One advantage of the disclosed embodiments is that corrugated composite reinforcements (such as corrugated cap reinforcements) exhibiting reduced wrinkling and / or having smaller wrinkles of acceptable size can be manufactured. Another advantage is the diffusion of wrinkling in the composite cap stringers caused by the formation of the corrugations, thereby improving stringer performance. Another advantage is the reduction or elimination of stringer rework due to inconsistencies, thereby saving labor costs. Other advantages include the reduction or elimination of scrapped stringers due to unacceptably large wrinkles.

[0009] The features, functions, and advantages discussed may be implemented independently in various examples of this disclosure, or may be combined in other examples, as further details of which may be understood with reference to the following description and figures. Attached Figure Description

[0010] The appended claims set forth novel features believed to be characteristic of the exemplary embodiments. However, the exemplary embodiments, preferred modes of use, other objects, and descriptions thereof will be best understood when read in conjunction with the accompanying drawings by referring to the following detailed description of exemplary examples of this disclosure, wherein:

[0011] Figure 1 This is an example of a three-dimensional view of a wave-shaped hat-shaped stringer.

[0012] Figure 2 It shows Figure 1 An example of the cross-sectional shape of a hat-shaped stringer is shown.

[0013] Figure 3 It is used to form Figure 1 An example of a sectional view of a tool group for a hat-shaped stringer.

[0014] Figure 4 It is similar to Figure 3 An example is shown, but it illustrates that the composite material has been shaped into... Figure 2 The punch with the cross-sectional shape shown in the figure.

[0015] Figure 5 It is used to change Figure 3 and Figure 4 An example of a side view of the mechanism of the tool group's waveform is shown in the figure.

[0016] Figure 6 It is formed Figure 3 and Figure 4 An example of a three-dimensional view of a punch, which is part of the tool set shown in the figure.

[0017] Figure 7 yes Figure 6 An example of the bottom plan view of the punch shown in the figure.

[0018] Figure 8 yes Figure 6 and Figure 7 An example of a side view of a punch is shown.

[0019] Figure 9 Is Figure 8 An example of a region designated as "9".

[0020] Figure 10 It is along Figure 9 An example of a cross-sectional view taken from line 10-10 in the diagram.

[0021] Figure 11 It is along Figure 9 An example of a cross-sectional view taken from line 11-11 in the diagram.

[0022] Figure 12 This is an example of a partial side view of the hat-shaped stringer during the waveform formation by the punch.

[0023] Figure 13 Is Figure 12 An example of the region designated as "13".

[0024] Figure 14 This is an example of a graphical view showing how the opening in the punch can be closed during the formation of the hat-shaped stringer waveform.

[0025] Figure 15 This is an example of a side view of a cap with a wave-shaped stringer, showing the formation of small folds.

[0026] Figure 16 This is an example of a cross-sectional view of another punch.

[0027] Figure 17 This is an example of a three-dimensional view of a compactor.

[0028] Figure 18 This is an example of an exploded side view, showing how it can be used. Figure 17 The compactor shapes the straight cap-shaped stringers into the desired waveform.

[0029] Figure 19 This is an example of a perspective view of another example of a compactor positioned for picking up and transporting cap-shaped stringers.

[0030] Figure 20 yes Figure 19 An example of a cross-sectional view of a compactor, which is positioned to place and shape a cap-shaped stringer to abut against a forming die to form a wave.

[0031] Figure 21 This is an example of a flowchart illustrating a method for manufacturing corrugated cap-shaped stringers with reduced wrinkling.

[0032] Figure 22 It is a flowchart illustrating the methods of aircraft manufacturing and maintenance.

[0033] Figure 23 It is a diagram of an airplane. Detailed Implementation

[0034] First, refer to Figure 1 and Figure 2 The cap-shaped stringer 30, having one or more out-of-plane curvatures, includes a cap 32 and a pair of outwardly bent flanges 42. The cap 32 includes a substantially flat cover 34 connected to the flanges 42 by a pair of inclined webs 38. The cap-shaped stringer 30 may have other cross-sectional shapes, such as a dome shape (not shown).

[0035] The cap stringer 30 comprises a composite laminate formed of multiple layers of fiber-reinforced polymers, such as thermosetting or thermoplastic plastics. As will be discussed below, the cap stringer 30 may have one or more out-of-plane waveforms or curvatures along its length. Figure 1 In the example shown, the cap-shaped stringer 30 has a single constant curvature in the XZ plane within the coordinate system shown in 44. Specifically, refer to... Figure 1 As will be discussed later, during the process of forming the cap stringer 30 into the desired cross-sectional shape, the shaping and wave-forming process results in the region 36 of the cap 34 along the inner radius of the cap portion 32 being in a state of compression 40. In one example, the wave of the cap stringer 30 is formed simultaneously with the cap stringer being formed into the desired cross-sectional shape. Alternatively, in another example, the wave of the cap stringer 30 can be formed along its length in a separate operation after the cap stringer 30 has been formed into the desired cross-sectional shape. In each of these examples, due to the wave-forming, the region 36 of the cap 34 along its length where the wave is formed is in a state of compression 40. Compression 40 of the cap 34 in this manner during stringer wave-forming can result in unacceptably large wrinkles forming in the cap 34 or in other areas of the cap portion 32.

[0036] Figure 3 and Figure 4An example of a tool set 48 is illustrated for shaping a flat composite charge 64 into a corrugated cap-shaped stringer 30 exhibiting reduced wrinkling. The tool set 48 includes a tool 54 and a pair of dies 56, the tool 54 being a punch 55 in this example, the dies 56 being spaced apart to form a die cavity 62. The punch 55 is formed of a flexible material such as an elastomer, nylon, or PTFE (polytetrafluoroethylene) (to name just a few), allowing it to bend as needed. In the illustrated example, the punch 55 is mounted on the bottom of a flexible top plate 50, which may include, for example, but is not limited to, an aluminum sheet. However, in other examples, the top plate 50 may also be an elastomer or other polymer integrally formed with the punch 55. The cross-sectional shape of the punch 55 is similar to that of the cap 32 (…). Figure 2 The IML (inner mold line) of the tool set 48 is basically matched. The tool set 48 can be installed on the press 70. Figure 5 In the press 70, the pressure plate 72 causes the top plate 50 and the bottom plate 52 to move relative to each other, thereby causing the punch 55 to be displaced into the mold cavity 62 with a desired force and at a desired rate.

[0037] The mold 56 is mounted to facilitate lateral movement 66 on the flexible base plate 52. In one example, the mold 56 includes a series of interconnected mold blocks that allow the mold 56 to bend out of plane. A pair of side rails 60 are fixed to the base plate 52 on the outside of the mold 56. Inflatable side airbags 58 are located between the mold 56 and the side rails 60, respectively. The side airbags 58 may be inflated with fluid (such as air) and are used to control the outward lateral movement of the mold 56 during the molding process.

[0038] The stringer forming operation begins as follows Figure 3 The tool assembly 48 is arranged as shown, with the punch 55 in an elevated position. A flat composite material 64 is placed on the die 56, spanning the die cavity 62. In order to shape the flat composite material 64 into the desired cross-sectional shape of the cap stringer 30, the top plate 50 moves downward, causing the punch 55 to shape the composite material 64 into the die cavity 62.

[0039] In one example, as previously mentioned, a waveform changing mechanism 68 is used, for example, before shaping the composite charge into the desired cross-sectional shape. Figure 5 The tool set 48 is shaped into a waveform along its length. Therefore, in this example of the forming sequence, the composite charge 64 is formed into the mold cavity 62, which has already been shaped into a waveform along the length of the mold cavity 62. Thus, compression of the waveform region 36 of the cap 34 occurs while the cross-sectional shape of the cap 32 is being formed.

[0040] In another example of the forming sequence, the composite material 64 is formed into the mold cavity 62 before the tool assembly 48 forms a waveform along its length. In this case, compression of the waveform region 36 of the cap 34 occurs after the cross-sectional shape of the cap 32 has been formed, while the cap 32 is forming a waveform along its length. Regardless of which of these forming sequences is used, the waveform forming process results in compression 40 of the cap 34. Figure 1 The compression creates stress in cover 34, which can lead to unacceptably large wrinkles.

[0041] The focus now is on Figures 6 to 11 , Figures 6 to 11 An example of a tool 54 for forming a hat-shaped stringer 30 with reduced large-scale wrinkling is illustrated. In this example, tool 54 comprises a tool body 80 in the form of a punch 55 having an external shape that matches the external shape of the hat portion 32 of the hat-shaped stringer 30. As previously discussed, punch 55 is formed of a flexible but sufficiently rigid material to shape the composite charge into the desired stringer shape. In one example, punch 55 may be attached to top plate 50 by any suitable means. In another example, top plate 50 and punch 55 are a one-piece construction, integrally formed from the same material.

[0042] The tool body 80 is provided with a plurality of first openings 82 and a plurality of second openings 84. Each of the openings 82, 84 may include a slit or slot in the tool body 80. In the illustrated example, the first openings 82 and the second openings 84 are regularly spaced apart from each other by a desired distance 94. Figure 9 The openings 82 and 84 are arranged in an alternating relationship. In other examples discussed below, the openings 82 and 84 may be irregularly spaced apart and may be arranged in other orders. The width 90 of the first opening 82 and the width 92 of the second opening 84 will depend on the application. In the illustrated example, the first opening 82 extends across the punch 55 and through the entire height 86 of the punch 55, giving the punch 55 flexibility. The second opening 84 extends partially across the punch 55, but its height 88 is less than the height 86 of the punch 55. Figure 11 Thus, the solid part 100 in the punch 55 is obtained directly above each second opening 84.

[0043] Now, according to Figures 12 to 15When the punch 55 shapes the composite filler 64 into the desired waveform, the first opening 82 partially or completely closes 112, allowing the punch 55 to bend into the desired waveform. However, the second set of openings 82 remains open during this bending because the solid portion 100 above the second openings 84 prevents them from closing. Therefore, because the second set of openings 84 remains open during waveform formation, portions of the composite filler 64 can be strained into the second set of openings 84 and form a series of small folds 110, the size of which is acceptable due to its small size, and the folds 110 do not individually or collectively substantially affect the performance of the cap stringer 32. The stress in the composite filler 64 obtained through the waveform formation process is redirected to the IML (inner mold line) of the cap stringer 30, where these stresses are relieved by the strain of the composite filler 64 into the second set of openings 84 and the formation of small folds 110 of acceptable size. In fact, the strain along the inner radius of the cap-shaped stringer in the composite charge 64 caused by the waveform formation process is diffused, resulting in a series of small folds 110, rather than larger folds.

[0044] Figure 16 Another example of the punch 55 is illustrated, wherein the second set of openings 84 includes a groove 96 formed in the surface of the tool body 80. The groove 96 may extend partially or completely around the punch 55 and has a depth 97 sufficient to allow small folds 110 to be formed in the groove 96 when the cap string 30 is being shaped into a wave.

[0045] Reference Figure 17 Tool 54 may include a compactor 114, which can be used to corrugate a straight stringer already formed to a desired cross-sectional shape and then compact it. The illustrated compactor 114 is formed of a composite material; however, in other examples, it may be formed of a suitable, bendable polymer. The compactor 114 includes a cap-shaped body 122 formed to match the shape of the cap stringer 30 and an outwardly extending flange 124. The compactor 114 includes a group of first openings 82 and second openings 84, which may take the form of a slit or slot similar to the slot or groove in the previously described punch 55. The first openings 82 and second openings 84 are arranged alternately along the length of the cap-shaped body 122. Each first opening 82 extends completely through the entire cross-section of the cap-shaped body 122 to the flange 124. The second opening 84 extends across the cap-shaped body 122 but terminates below the flange 124. Therefore, similar to the previously described punch 55, when the compactor 114 is bent into the desired waveform during the compaction / forming operation, the first opening 82 in the compactor 114 is partially or completely closed, while the second opening 84 remains open, thereby allowing small folds to be formed in the composite charge 64 as it is being shaped into a waveform.

[0046] ReferenceFigure 18 The compactor 114 can be used to form and / or compact composite charge that has been formed into a desired cross-sectional shape. The compactor 114 is placed within a straight forming stringer 116, and the combination of the compactor 114 and the forming stringer 116 is placed on a forming die 118 having a corrugated die surface 120. Pressure is then applied to the compactor 114 by any suitable device such as a vacuum bag (not shown), causing the compactor 114 to form the stringer 116 downward onto the corrugated die surface 120. Additional pressure may be applied by the compactor 114 to compact the corrugated cap-shaped stringer 116 onto the forming die 118.

[0047] The focus now is on Figure 19 and Figure 20 , Figure 19 and Figure 20 Another example of a compactor 114 is illustrated for conveying, corrugating, and / or compacting a cap-shaped stringer 30. In this example, the compactor 114 includes a one-piece cap-shaped body 122 and an integral flange 132 formed of a flexible material such as an elastomer. The cap-shaped body 122 includes a first opening 82 and a second opening 84, which may include slits or slots arranged as previously described. The compactor 114 includes an end wall 128 provided with a fitting 130 adapted to connect a hollow cavity 126 to a vacuum source (not shown). A vacuum applied to the hollow cavity 126 causes air to be drawn in through the openings 82, 84, thereby creating a suction effect. When the compactor 114 is placed inside the straight cap stringer 30 and suction is performed inside the compactor 114, the cap stringer 30 is drawn against the compactor 114, thereby enabling the compactor 114 to pick up the cap stringer 32 and transport it to different locations, such as to the forming station (not shown).

[0048] Figure 20 The diagram shows that the compactor 114 has picked up the cap stringer 30 using suction drawn through openings 82, 84, and is about to lower the cap stringer 30 142 into the mold cavity 136 in the forming mold 134. The forming mold 134 includes a mold surface 138 that is wavy along its length. After the cap stringer 30 is placed in the mold cavity 136, forming pressure is applied to the compactor 114, causing the cap stringer 30 to be shaped into the wavy shape of the mold cavity 136. Additional pressure applied to the compactor 114 by any suitable device such as a vacuum bag (not shown) causes the wavy cap stringer to be compacted onto the forming mold 134.

[0049] The focus now is on Figure 21 , Figure 21The overall steps of a method for forming a corrugated cap stringer 30 exhibiting reduced wrinkling are generally illustrated. Starting at 144, a flat composite material 64 is shaped into the desired cross-sectional shape using a tool 54, such as a punch 55. At 145, the cap stringer 30 is shaped into a corrugation, which includes bending the tool. At 146, a set of first openings 82 in the tool 54 allows the tool 54 to bend into the desired corrugation. At 148, a set of second openings 84 in the tool 54 relieves stress in the composite material 64 by allowing the composite material 64 to strain into the second openings 84.

[0050] Examples of this disclosure can be found in a variety of potential applications, particularly in the transportation industry, including, for example, aerospace, marine, automotive applications, and other applications where corrugated reinforcements (such as corrugated cap stringers in aircraft) can be used. Therefore, reference is now made to... Figure 22 and Figure 23 , can be as Figure 22 The aircraft manufacturing and maintenance methods 150 shown are as follows: Figure 23 Examples of this disclosure are used in the context of the aircraft 152 shown. Aircraft applications of the disclosed examples may include various composite reinforcements, such as stringers having wave-like patterns, curvature, varying thickness, or other non-uniformities along their length. In the pre-production process, exemplary method 150 may include the specification and design 154 of the aircraft 152 and material procurement 156. During production, the manufacturing of aircraft parts and sub-assemblies 158 and system integration 160 are performed. Thereafter, the aircraft 152 may be inspected and delivered 162 for entry into service 164. During its entry into service with the customer, the aircraft 152 is scheduled for routine maintenance and overhauls 166, which may also include modifications, refits, refurbishments, etc.

[0051] Each of the processes in method 150 may be performed or executed by a system integrator, a third party, and / or an operator (e.g., a customer). For the purposes of this description, a system integrator may include, but is not limited to, any number of aircraft manufacturers and main system subcontractors; a third party may include, but is not limited to, any number of suppliers, subcontractors, and vendors; and an operator may be an airline, leasing company, military entity, service organization, etc.

[0052] like Figure 23 As shown, an aircraft 152 produced using the exemplary method 150 may include a fuselage 166 having multiple advanced systems 168 and an interior 170. Examples of advanced systems 168 include one or more of a propulsion system 172, an electrical system 174, a hydraulic system 176, and an environmental system 178. Any number of other systems may be included. Although an aerospace example is shown, the principles of this disclosure can be applied to other industries such as the maritime and automotive industries.

[0053] The systems and methods implemented herein may be employed during any one or more stages of the aircraft manufacturing and maintenance method 150. For example, components or sub-assemblies corresponding to production process 158 may be made or manufactured in a manner similar to the production of components or sub-assemblies of aircraft 150 during service 164. Additionally, one or more equipment examples, method examples, or combinations thereof may be utilized during production processes 158 and 160, for example, by significantly accelerating the assembly of aircraft 152 or reducing the cost of aircraft 152. Similarly, one or more equipment examples, method examples, or combinations thereof may be utilized when aircraft 152 is in service (e.g., but not limited to maintenance and overhaul 166).

[0054] This disclosure includes illustrative examples in accordance with the following terms.

[0055] Clause 1. A tool (54) for forming a composite filler (64) into a corrugated composite stringer (30), said tool comprising:

[0056] The tool body (80) is flexible and has length.

[0057] The tool body (80) has a set of laterally extending first openings (82), the first openings (82) being configured to allow the tool body (80) to bend during the forming of the composite filler (64).

[0058] The tool body (80) has a set of laterally extending second openings (84), and a portion (110) of the composite charge (64) can be strained into the second openings (84) during forming.

[0059] Clause 2. The instrument (54) described in Clause 1, wherein:

[0060] The first opening (82) is configured to be at least partially closed (112) during the forming of the composite charge (64), and

[0061] The second opening (84) is configured to remain substantially open during the forming of the composite charge (64).

[0062] Clause 3. The tool (54) according to Clause 1 or 2, wherein the tool body (80) has a cross-sectional shape substantially matching the cross-sectional shape of the composite stringer (30).

[0063] Clause 4. The instrument (54) described in Clause 3, wherein:

[0064] The first openings (82) all extend completely across the cross-sectional shape of the tool body (80), and

[0065] The second opening (84) extends only partially across the cross-sectional shape of the tool body (80).

[0066] Clause 5. The tool (54) according to any one of Clauses 1 to 4, wherein the first opening (82) and the second opening (84) are arranged alternately along the length of the tool body (80).

[0067] Clause 6. The tool (54) according to any one of Clauses 1 to 5, wherein the tool body (80) is a compactor (114) configured to compact the composite charge (64) against the surface (120) of the wave mold.

[0068] Clause 7. The instrument (54) pursuant to any one of Clauses 1 to 6, wherein:

[0069] The tool body (80) is a punch (55), which is configured to form the composite charge (64) into the mold cavity (62), and

[0070] Each of the first opening (82) and the second opening (84) is a groove in the punch (55).

[0071] Clause 8. The tool (54) according to any one of Clauses 1 to 7, wherein each of the second openings (84) is a groove (96) in the surface of the tool body (80).

[0072] Clause 9. The tool (54) according to any one of Clauses 1 to 8, wherein each of the second openings (84) has a width (90) configured to allow pleats (110) in the composite charge (64) to be formed in the second opening (84) during forming.

[0073] Clause 10. A tool (54) for shaping a composite charge (64) into a corrugated stringer (30) having a desired cross-sectional shape, said tool (54) comprising:

[0074] A punch (55) is configured to form the composite charge (64) into a forming string (30) having a desired cross-sectional shape, and to form a wave along the length of the forming string (30).

[0075] The punch (55) has an opening (84) into which the composite charge (64) can be strained when the forming string (30) is forming a waveform along its length.

[0076] Clause 11. The tool (54) as described in Clause 10, wherein the punch (55) is formed of a flexible material.

[0077] Clause 12. The instrument (54) described in Clause 10 or 11, wherein:

[0078] The punch (55) is flexible along its length and is configured to bend as the forming string (30) forms a wave, and

[0079] The opening (84) includes a slot (84) in the punch that extends laterally through the punch (55), and each slot (84) is configured to remain open as the forming string (30) is forming a waveform.

[0080] Clause 13. The tool (54) according to Clause 12, wherein the punch (55) includes an opening (82) configured to give the punch flexibility and to at least partially close (112) when the forming string (30) is forming a waveform.

[0081] Clause 14. The tool (54) according to any one of Clauses 10 to 13, wherein the opening (84) for the composite charge to be strainably inserted and the opening (82) for giving flexibility to the punch (55) are arranged in an alternating relationship with each other along the length of the punch (55).

[0082] Clause 15. The tool (54) according to any one of Clauses 10 to 14, wherein the opening (84) into which the composite charge (64) can be strained is a groove (84) extending partially into the surface of the punch (55).

[0083] Clause 16. A method for manufacturing a wrinkle-reduced corrugated composite stringer (30), the method comprising the steps of:

[0084] Using tool (54), the flat composite material (64) is shaped into stringers (30) with the desired cross-sectional shape;

[0085] To form a wave shape for the stringers (30), this includes bending the tool (54);

[0086] The tool is made able to bend by using the first set of openings (82); and

[0087] The second set of openings (84) in the tool is used to reduce stress in the composite material (64) during waveform formation by allowing a portion (110) of the composite material (64) to strain into the second set of openings (84).

[0088] Clause 17. The method described pursuant to Clause 16, wherein:

[0089] The step of forming the flat composite charge (30) is performed using a punch (55), and

[0090] Using the first set of openings (82) includes enabling the first set of openings (82) to be at least partially closed during waveform formation.

[0091] Clause 18. The method according to Clause 16 or 17, wherein using the second set of openings (84) in the tool includes keeping each of the second set of openings (84) open during waveform formation.

[0092] Clause 19. The method according to any one of Clauses 16 to 18, wherein the step of forming a waveform is performed using a compactor (114).

[0093] Clause 20. The method according to any one of Clauses 16 to 19, the method further comprising the following steps:

[0094] A vacuum is created by drawing in air through at least some of the first set of openings (82) and the second set of openings (84); and

[0095] Vacuum is used to draw the stringer (30) against the tool (54).

[0096] As used herein, the phrase “at least one” when used with a list of items means that different combinations of one or more of the listed items may be used, and only one of each item in the list may be required. For example, “at least one of item A, item B, and item C” may include, but is not limited to, item A, item A and item B, or item B. This example may also include item A, item B, and item C, or item B and item C. The item may be a specific thing, thing, or category. In other words, “at least one” means that any combination of items and multiple items may be applicable to the list, and not all items in the list are required.

[0097] Various illustrative examples have been shown for purposes of illustration and description, but this description is not intended to be exclusive or limited to the examples of the disclosed forms. Many modifications and variations will be apparent to those skilled in the art. Furthermore, different illustrative examples may offer different advantages compared to other illustrative examples. One or more examples have been selected and described in order to best illustrate the principles and practical applications of the examples, and to enable those skilled in the art to understand that this disclosure contains various examples with various modifications suitable for the particular intended use.

Claims

1. A tool (54) for forming a composite charge (64) into a corrugated composite stringer (30), said tool comprising: The tool body (80) is flexible and has length. The tool body (80) has a set of laterally extending first openings (82) configured to allow the tool body (80) to bend during the forming of the composite material (64), and the height of each first opening (82) is equal to the height of the tool body (80). The tool body (80) has a set of laterally extending second openings (84), a portion (110) of the composite charge (64) being able to strain into the second openings (84) during forming, each of the second openings (84) having a height less than the height of the tool body (80) and the second openings (84) being configured to remain at least partially open during forming of the corrugated composite stringer (30), wherein a solid portion of the tool body (80) directly above each of the second openings (84) prevents each of the second openings (84) from being completely closed during forming.

2. The tool (54) according to claim 1, wherein: The first opening (82) is configured to be at least partially closed (112) during the forming of the composite charge (64), and The second opening (84) is configured to remain substantially open during the forming of the composite charge (64).

3. The tool (54) according to claim 1, wherein, The tool body (80) has a cross-sectional shape that substantially matches the cross-sectional shape of the wave composite stringer (30).

4. The tool (54) according to any one of claims 1 to 3, wherein, The first opening (82) and the second opening (84) are arranged alternately along the length of the tool body (80).

5. The tool (54) according to any one of claims 1 to 3, wherein, The tool body (80) is a compactor (114) configured to compact the composite charge (64) against the surface (120) of the wave mold.

6. The tool (54) according to any one of claims 1 to 3, wherein: The tool body (80) is a punch (55), which is configured to form the composite charge (64) into the mold cavity (62), and Each of the first opening (82) and the second opening (84) is a groove in the punch (55).

7. The tool (54) according to any one of claims 1 to 3, wherein, Each of the second openings (84) has a width (90) configured to allow wrinkles in the composite charge (64) to be formed in the second opening (84) during forming.

8. A tool (54) for shaping a composite charge (64) into a corrugated composite stringer (30) having a desired cross-sectional shape, said tool (54) comprising: A punch (55) is configured to form the composite charge (64) into a forming string having a desired cross-sectional shape, and to cause the forming string to form a wave along its length. The punch (55) has a plurality of first openings (82), the height of each first opening (82) being equal to the height of the punch (55). The punch (55) has a plurality of second openings (84) into which the composite charge (64) can be strained as the forming string is forming a waveform along its length. The height of each second opening (84) is less than the height of the punch (55) and the second openings (84) are configured to remain at least partially open during the forming of the forming string, wherein a solid portion of the punch (55) directly above each second opening (84) prevents each second opening (84) from being completely closed during the forming.

9. The tool (54) according to claim 8, wherein, The punch (55) is formed of a flexible material.

10. The tool (54) according to claim 8, wherein: The punch (55) is flexible along its length and is configured to bend as the forming stringer is forming a waveform, and The second opening (84) includes a slot in the punch that extends laterally through the punch (55), each slot being configured to remain open as the forming stringer is forming a waveform.

11. The tool (54) according to claim 10, wherein, The first opening (82) is configured such that the punch is flexible and at least partially closed (112) when the forming string is forming a waveform.

12. The tool (54) according to any one of claims 8 to 11, wherein, The second opening (84) that allows the composite charge to be strained into and the first opening (82) that gives flexibility to the punch (55) are arranged alternately to each other along the length of the punch (55).

13. A method for manufacturing a corrugated composite stringer (30) with reduced wrinkling, the method comprising the steps of: The flat composite charge (64) is shaped into a stringer having the desired cross-sectional shape using the tool (54) according to any one of claims 1 to 12; To form the stringers into a wave shape, this includes bending the tool (54); The tool is made able to bend by using the first opening (82) in the tool; as well as The second opening (84) in the tool is used to reduce the stress in the composite material (64) during waveform formation by allowing a portion (110) of the composite material (64) to strain into the second opening (84).

14. The method of claim 13, wherein: Using the first opening (82) includes enabling the first opening (82) to be at least partially closed during waveform formation.

15. The method according to claim 13 or 14, wherein, Using the second opening (84) in the tool includes keeping each of the second openings (84) open during waveform formation.

16. The method according to claim 13 or 14, wherein, The step of forming a waveform is performed using a compactor (114).

17. The method according to claim 13 or 14, further comprising the step of: A vacuum is created by drawing in air through at least some of the first opening (82) and the second opening (84); as well as Vacuum is used to draw the stringers against the tool (54).

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