Restrained shaping of profiled composite hat stringers

Abstract

In forming a hat stringer from a flat composite layup, the cover portion is reduced in cover portion wrinkles in the formed composite hat stringer by constraining the cover portion. The cover portion is constrained by an inflatable bladder placed in the tool set for forming the composite layup.

Description

Technical Field

[0001] This disclosure generally relates to methods and apparatus for manufacturing composite reinforcements, and more specifically, to a method and apparatus for manufacturing shaped composite cap stringers with reduced wrinkles. Background Technology

[0002] Various processes and equipment can be used to form flat composite fillers into stiffeners, such as stringers, with desired cross-sectional shapes. For example, stringers can be manufactured by forming the composite filler into a mold cavity using a stamping press or an inflatable bladder. In those applications where the stringer is formed along its length as part of the forming process, localized stresses are generated within the composite filler during forming, which can cause bending or wrinkling in the areas of the stringer containing these stresses. In the case of formed stringers with a cap-shaped cross-section (“cap stringers”), stresses tend to form in the formed areas of the stringer and cause bending or wrinkling of the cap. Bending or wrinkling of the cap is undesirable because it can affect the structural performance of the stringer, leading to the need for stringer rework or changes in stringer design, which can increase labor and / or material costs.

[0003] Therefore, it is desirable to provide a method and apparatus for manufacturing shaped cap-shaped stringers that reduces or eliminates bending and / or wrinkles in the cap, particularly in the shaped portion of the stringer. Summary of the Invention

[0004] This disclosure generally relates to the manufacture of composite parts, and more specifically, to methods and apparatus for producing molded composite cap-shaped stringers with reduced wrinkles.

[0005] According to one aspect, an apparatus is provided for manufacturing a molded composite cap-shaped stringer. The apparatus includes a pair of dies, a press, and a capsule. The dies are configured to form along their length and define a die cavity into which composite material can be formed to form a molded cap-shaped portion having a cap. The press is configured to form the composite material into the die cavity. The capsule is located within the die cavity and is configured to constrain the cap during the formation of the molded cap-shaped portion.

[0006] According to another aspect, a method for forming a molded composite cap-shaped stringer with reduced wrinkles is provided. The method includes: forcing a composite material into a molded cap-shaped portion having sides and a cap by forcing the composite material into a mold cavity. The method further includes: reducing stress in the cap during forming by constraining the cap.

[0007] According to another aspect, a method is provided for forming a molded composite cap-shaped stringer having a cap-shaped portion including sides and a cap. The method includes: placing a flat composite material onto a pair of molds defining a mold cavity; and forcing the flat composite material into the mold cavity to form the cap-shaped portion of the stringer having sides and a cap. The method further includes: forming the mold cavity; and reducing wrinkles in the cap during the formation of the cap-shaped portion by transferring stress in the cap away from the cap.

[0008] One advantage of the disclosed method and apparatus is that it can produce molded composite cap-shaped stringers in which wrinkles in the molded area of ​​the cap are reduced or eliminated. Another advantage is that the method can be achieved using only minor modifications to existing stringer forming equipment. Yet another advantage is that it reduces or eliminates rework caused by stringer wrinkles and the associated labor and material costs. A further advantage is that reduced cap wrinkles improve the structural performance of the cap-shaped stringer.

[0009] Features, functions, and advantages may be implemented independently in the various examples of this disclosure, or may be combined in other examples, more details of which can be seen with reference to the following specification and figures. Attached Figure Description

[0010] The appended claims set forth novel features that are considered exemplary examples. However, the exemplary examples, preferred modes of use, further objectives and advantages thereof will be best understood by referring to the following detailed description of exemplary examples of this disclosure when read in conjunction with the accompanying drawings, wherein:

[0011] Figure 1 This is a three-dimensional illustration of an example of a composite cap-shaped stringer.

[0012] Figure 2 It is shown Figure 1 An illustration of the end view of the cross-sectional shape of the composite hat-shaped stringer shown.

[0013] Figure 3 This is an illustration of an end view showing the cross-sectional shape of another example of a composite cap stringer.

[0014] Figure 4 It is a three-dimensional illustration of a composite cap-shaped truss with multiple profiles along its length.

[0015] Figure 5 This is a cross-sectional view of a tool set used to manufacture shaped composite hat-shaped stringers.

[0016] Figure 5A yes Figure 5 A perspective view of the press and top plate, wherein the press is segmented along its length.

[0017] Figure 6 It shows the movement Figure 5 A cross-sectional view illustrating an alternative method for the mold forming section of the tool set shown.

[0018] Figure 7 It is similar to Figure 5 The illustration shows a flat composite charge placed on a mold and a venting bladder installed inside the mold cavity.

[0019] Figure 8 yes Figure 7 The illustration shows a three-dimensional view of the deflation bladder-like structure.

[0020] Figure 9 It is similar to Figure 7 The illustration shows that the capsule has been inflated and the press has formed the composite filling portion in the mold cavity.

[0021] Figure 10 yes Figure 9 China was designated as " Figure 10 A diagram of the area marked "".

[0022] Figure 11 It is similar to Figure 9 The illustration shows a view, but it does not show that the press has fully formed the composite charge into the die cavity.

[0023] Figure 12 It is similar to Figure 10 The illustration is used to explain the benefits of constraining the cap during the forming process; for clarity, the cap clamping sac is not shown.

[0024] Figure 13 This is an illustration of a partial side view of a part of a stamping press, in which the constraint effect of the bladder has forced the composite charge to locally strain into the slit of the stamping press.

[0025] Figure 14 This is a side view illustration of a contour-changing mechanism used to form a composite hat-shaped stringer.

[0026] Figure 15 This is a functional block diagram of an apparatus for producing molded composite cap-shaped stringers with reduced wrinkles.

[0027] Figure 16 This is a flowchart illustrating a method for manufacturing molded composite cap-shaped stringers with reduced wrinkles.

[0028] Figure 17 This is a flowchart illustrating another method for manufacturing molded composite cap-shaped stringers with reduced wrinkles.

[0029] Figure 18 It is a flowchart illustrating the process of aircraft production and service.

[0030] Figure 19 It is a block diagram illustration of an aircraft. Detailed Implementation

[0031] First see Figure 1 and Figure 2 A hat-shaped stringer 20 having one or more out-of-plane curvatures includes a hat-shaped portion 22 and a pair of outwardly oriented flanges 28. The hat-shaped portion 22 includes a generally flat cap 24 coupled to the flanges 28 via a pair of inclined sides 26 (sometimes referred to as webs). The hat-shaped stringer 20 may have other cross-sectional shapes. For example, Figure 3 A hat-shaped stringer 20 is shown, which has a hat-shaped portion 22 including a circular cap 24 that smoothly transitions to a side portion 26.

[0032] The cap stringer 20 may comprise a composite laminate formed of multiple layers of fiber-reinforced polymers (such as thermosetting or thermoplastic materials). As will be discussed below, the cap stringer 20 may have one or more out-of-plane profiles or curvatures along its length. Figure 1 In the example shown, the hat-shaped stringer 20 has a single constant curvature in the XZ plane within the coordinate system shown in 30. Figure 4 Another example of a cap-shaped stringer 20 having a profile in both the XZ and XY planes is shown. Specifically, refer to... Figure 1 As will be discussed later, during the shaping of the cap stringer 20 into the desired cross-sectional shape, the region 25 of the cap portion 24 along the inner diameter of the cap portion 22 may be placed in compression 27 due to the forming and contouring processes. In one example, the shaping of the cap stringer 20 occurs as the cap stringer is shaped into the desired cross-sectional shape. Alternatively, in another example, the cap stringer 20 is shaped along its length in a separate operation after it has been shaped into the desired cross-sectional shape. In each of these examples, the shaped region 25 of the cap portion 24 is placed in compression 27 along its length due to the shaping process. In this way, the compression 27 of the cap portion 24 during stringer forming can cause the cap portion 24 to bend or wrinkle.

[0033] Now turn attention to Figure 5-11 It shows an apparatus 33 for forming a flat composite charge 56 into a shaped cap stringer 20 with a wrinkle-reduced cap 24. The apparatus 33 includes a tool set 34 comprising a stamping press 40 and a pair of dies 42 spaced apart to form a die cavity 48. See also Figure 5A The press 40 can be segmented along its length to allow for buckling and is mounted on the bottom of the flexible top plate 36. The cross-sectional shape of the press 40 substantially matches the cap-shaped portion 22. Figure 2The IML (Inner Mold Line) of the tooling assembly 34. In other examples of tooling assembly 34, an inflatable bladder (not shown) may be used instead of the press 40 to form the flat composite charge 56 downward into the die cavity 48. Tooling assembly 34 may be mounted in a press (not shown) having a pressure plate (not shown) that moves the top plate 36 and the bottom plate 38 relative to each other, causing the press 40 to be displaced into the die cavity 48 with a force F of a desired rate and magnitude.

[0034] The mold 42 is mounted on a flexible base plate 38 for lateral movement 50. In one example, the mold 42 is segmented along its length to allow it to buckle out of plane. In another example, the mold 42 may each comprise a series of individual mold blocks (not shown), which similarly allow the mold 42 to buckle out of plane. On the outer side of the mold 42, a pair of side rails 46 are fixed to the base plate 38. Inflatable side bladders 44 are located between the mold 42 and the side rails 46, respectively. The side bladders 44 can be inflated with fluid (e.g., air) and are used to control the outward lateral movement of the mold 42 during molding. In other examples, such as... Figure 6 As shown, the lateral movement of the mold 42 can be controlled by a mechanical actuator 52 or a similar mechanism coupled to each mold 42 via a drive rod 54.

[0035] See Figure 7 and Figure 8 An inflatable clamping bladder 60 is mounted within the mold cavity 48. This clamping bladder rests on the base plate 38 until it is inflated with air or another suitable pressurized fluid. The cap clamping bladder 60 can be formed of any suitable material, such as an elastomer with sufficient rigidity to apply pressure to and constrain the cap 24 of the cap-shaped portion 22 during the molding process. To achieve the desired rigidity, in some examples, the cap clamping bladder 60 may include local reinforcements (not shown). In the illustrated example, the cap clamping bladder 60 is sized to completely fill the mold cavity 48 and extend along the entire length of the mold cavity 48. However, in other examples, the clamping bladder 60 may only be located in a portion of the mold cavity 48, in which compression of the cap 24 may be sufficient to cause bending or wrinkling of the cap 24.

[0036] The stringer forming operation begins as follows Figure 5 The tool set 34 is arranged as shown, with the press 40 in the raised position. Next, as... Figure 7As shown, the cap clamping bladder 60 is installed in the mold cavity 48 in a deflated or partially deflated state. Then, the flat composite material 56 is placed on the mold 42 across the mold cavity 48. Next, a pair of flange clamping bladders 58 are installed between the outer edge 57 of the composite material 56 and the top plate 36. The flange clamping bladders 58 can be pressurized with air or other suitable fluid, and as will be described below, they are used to clamp the outer edge 57 of the composite material 56 onto the mold 42 when the press 40 "presses" the composite material 56 downward into the mold cavity 48.

[0037] To perform the forming operation, the top plate 36 moves downward, causing the press 40 to initially contact the composite material 56. Just before the press 40 contacts the composite material 56, the cover clamping bladder 60 is inflated, thus bringing it into contact with the bottom of the composite material 56 and applying pressure to that bottom. The top plate 36 continues to move downward ( Figure 9 and Figure 10 This causes the press 40 to begin forming the composite charge 56 into the die cavity 48. As the composite charge 56 is formed into the die cavity 48, the flange clamping bladder 58 applies pressure to the outer edge 57 of the composite charge 56, thereby keeping the outer edge flat against the die 42, while allowing the outer edge to slide on the die 42 for the remainder of the forming process.

[0038] As the press 40 forms the composite charge 56 into the die cavity 48, the pressurized cap clamping bladder 60 abuts against the cap 24 and applies pressure to the cap, thereby restricting the cap 24 from bending or wrinkling. The press 40 continues to move into the die cavity 48, causing the cap clamping bladder 60 to move onto the side 26 of the cap-shaped portion 22 and apply pressure to the side (see...). Figure 10 ), until the entire area of ​​the final cap-shaped portion 22 is almost completely enclosed and restrained by the cap clamping sac-like object 60. Figure 11 Depending on the application, it may be necessary to coordinate the pressure level of the cap clamping bladder 60 with the desired movement rate of both the press 40 and the die 42 to achieve optimal results.

[0039] In one example, as previously described, tooling 34 uses, for example, a profile-changing mechanism 74, which will be discussed later, before shaping the composite charge 56 into the desired cross-section. Figure 14The composite material 56 is formed along its length. Therefore, in this example of the forming sequence, the composite material 56 is formed into the mold cavity 48, which has previously been formed along its length, and thus, compression of the forming region 25 of the cap 24 occurs as the cross-sectional shape of the cap portion 22 is formed. In another example of the forming sequence, the composite material 56 is formed into the mold cavity before the tooling assembly (including the mold cavity 48) is formed along its length. In this latter example, compression of the forming region 25 of the cap 24 occurs after the cross-sectional shape of the cap portion 22 has been formed, as the cap portion 22 is formed along its length to its final contour. Regardless of which forming sequence is used, the cap clamping bladder constrains the cap 24, thereby sweeping away the stress in the cap 24 caused by compression to other areas of the cap portion 22 that are not subject to bending or wrinkling.

[0040] Figure 12 The diagram illustrates how the cap clamping bladder 60 is used to reduce or eliminate wrinkles in the cap 24 when the cap stringer 20 is formed into the desired profile. As previously described, when the cap portion 22 is formed in the forming area of ​​the cap stringer 20, the cap 24 is placed under compression, resulting in stress 62 within the cap 24, which can cause bending or wrinkling of the cap 24. To prevent such bending or wrinkling, the force 64 applied to the cap 24 by the cap clamping bladder 60 constrains the cap 24, thereby forcing the cap stress 62 to transfer 66 and distribute to other locations in the cap portion 22 that are not subject to bending or wrinkling. For example, the cap stress 62 may be transferred 66 to the side 26 of the cap portion 22, or it may be transferred longitudinally along the cap 24 to cap regions where the cap 24 is not under compression. In other words, the constraint imposed on the cover 24 by the cap clamping bladder 60 effectively relieves these stresses by sweeping the stress to other areas of the cap stringer 20.

[0041] refer to Figure 13 The force 64 applied to the cap 24 by the cap clamping bladder 60 in the forming area 25 of the cap-shaped portion 22 causes the material strain 72 in the composite charge 56 that is in contact with the press 40 to enter at least some of the slits 68 in the press 40. The material strain within the cap 24 entering the slits 68 helps to relieve some of the stress 62 in the cap 24, thereby further reducing the possibility of the cap 24 bending or wrinkling.

[0042] Various mechanisms can be used to construct tool sets 34 for forming one or more out-of-plane profiles in the hat-shaped stringer 20. Figure 14 An example of a profile-changing mechanism 74 for constructing tool set 34 to form cap-shaped stringer 20 is shown, the cap-shaped stringer being in the XZ plane ( Figure 1 and Figure 2The profile changing mechanism 74 may include, for example, but not limited to, a press 90. The press 90 includes a plurality of separate, spaced-apart actuators 76 mounted on opposing pressure plates 82, which are adapted to move toward and away from each other, as indicated by arrow 80. A tool assembly 34 is located between the pressure plates 82. The pressure plates 82 may be coupled to any suitable power-operated mechanism (e.g., a cylinder actuator (not shown)) that displaces the pressure plates 82 to open / close the tool assembly 34 during the compound loading forming operation. Each actuator 76 includes a drive rod 78 coupled to one of the top flexible plate 36 and the bottom flexible plate 38. The drive rod 78 displaces the top flexible plate 36 and the bottom flexible plate 38, which in turn bends (shapes) the die 42, thereby shaping the cap-shaped stringer 20. As previously described, the die 42 can be shaped before the compound loading 56 is “stamped” into the die cavity 48. However, alternatively, after the mold 42 has been formed by the contour changing mechanism 74, the composite charge 56 can be stamped into the mold cavity 48.

[0043] Now turn attention to Figure 15 The diagram outlines the components of an apparatus 33 for manufacturing a molded cap stringer 20 with reduced wrinkles. A controller 84 is coupled to and operable to control the operation of the press 90, the profile changing mechanism 74, and the pressurizing system 88. The controller 84 may include a PC (personal computer) or programmable controller operating under the control of one or more software programs 86. The pressurizing system 88 may include any suitable pump and fluid reservoir (not shown) operable to independently pressurize / depressurize (inflate / de-inflate) the side bladder 44, the flange clamping bladder 58, and the cap clamping bladder 60. The controller 84 controls and coordinates the operation of the profile changing mechanism 74, the press 90, and the pressurizing system 88, such that the forming and contouring processes proceed at a controlled rate. The controller 84 may also coordinate and synchronize the inflation of the cap clamping bladder 60 with the movement of the press 40 and the die 42.

[0044] Figure 16 The steps of a method for manufacturing a composite cap-shaped stringer 20 with reduced wrinkles are shown in general. Starting at 92, a cap-shaped portion 22 of the stringer having sides 26 and a cap 24 is formed by forcing a composite material 56 into a mold cavity 48. At 94, as the composite material 56 is forced into the mold cavity 48, the stress in the cap 24 generated during forming is reduced by constraining the cap 24.

[0045] Figure 17The steps of another example of a method for manufacturing a composite cap-shaped stringer 20 having a cap-shaped portion 22, the cap-shaped portion having a cap portion 24 and sides 26, are shown. At 96, a flat composite material 56 is placed on a pair of molds 42 defining a mold cavity 48 therebetween. At 98, the flat composite material 56 is forced into the mold cavity 48 to form the cap-shaped portion 22 of the cap-shaped stringer 20 having the cap portion 24 and sides 26. At 100, the cap-shaped portion 22 is formed along its length. At 102, stress in the cap portion 24 is directed away from the cap portion 24 by applying pressure to the cap portion 24 during the forming of the cap-shaped portion 22.

[0046] The examples disclosed herein can be used in a variety of potential applications, particularly in the transportation industry, including, for example, aerospace, marine, automotive applications, and other applications where hat-shaped stringers can be used. Therefore, reference is now made to... Figure 18 and Figure 19 ,exist Figure 18 The aircraft manufacturing and service method 104 shown herein and Figure 19 Examples of this disclosure can be used within the context of the aircraft 106 shown. Aircraft applications of the disclosed examples may include various shaped cap-shaped struts used on the fuselage 122 of aircraft 106. During pre-production, exemplary method 104 may include the specification and design 108 of aircraft 106 and material procurement 110. During production, component and sub-assembly manufacturing 112 and system integration 114 of aircraft 106 are performed. Aircraft 106 may then undergo certification and delivery 116 for entry into service 118. When servicing users, routine maintenance and upkeep 120 of aircraft 106 are performed periodically, which may also include modifications, redesigns, and refurbishments.

[0047] Each process in Method 104 may be performed or implemented by a system integrator, a third party, and / or an operator (e.g., a customer). For the purposes of this specification, 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 vendors, subcontractors, and suppliers; and an operator may be an airline, leasing company, military entity, service provider, etc.

[0048] like Figure 19 As shown, an aircraft 106 produced by exemplary method 104 may include a fuselage 122 having multiple systems 124 and an internal structure 126. Examples of high-level systems 124 include one or more of a propulsion system 128, an electrical system 130, a hydraulic system 132, and an environmental system 134. Any number of other systems may be included. While an aerospace example has been shown, the principles of this disclosure are applicable to other industries, such as the marine and automotive industries.

[0049] The systems and methods embodied herein can be used in any one or more stages of aircraft manufacturing and maintenance method 206. For example, components or sub-assemblies corresponding to production process 112 can be made or manufactured in a manner similar to that in which components and sub-assemblies are produced when aircraft 106 is in service. Moreover, during production processes 112 and 1114, one or more apparatus examples, method examples, or combinations thereof can be utilized, for example, by significantly accelerating the assembly of aircraft 106 or reducing its cost. Similarly, when aircraft 106 is in service, such as, but not limited to, maintenance and servicing 120, one or more apparatus examples, method examples, or combinations thereof can be used.

[0050] This disclosure includes exemplary implementations according to the following provisions:

[0051] Clause 1. An apparatus (33) for manufacturing a molded composite cap-shaped stringer (20), comprising:

[0052] A pair of molds (42) are configured to form along the length and define a mold cavity (48), and a composite charge (56) can be formed into the mold cavity to form a molded cap-shaped portion (22) with a cover (24);

[0053] A stamping press (40) is configured to form a composite charge (56) into a die cavity (48); and

[0054] A sac-like structure (60) is located within the mold cavity (48) and is configured to constrain the cap portion (24) during the formation of the molded cap portion (22).

[0055] Clause 2. The device (33) according to Clause 1, wherein the capsule (60) is formed of an elastomer.

[0056] Clause 3. The device (33) according to Clause 1 or 2, wherein the bladder (60) has sufficient rigidity to constrain the cap (24) when forming the composite charge (56).

[0057] Clause 4. The device (33) according to any one of Clauses 1-3, wherein the capsule (60) is located between the molds (42) and below the composite charge (56).

[0058] Clause 5. The device (33) according to any one of Clauses 1-4, wherein the bladder (60) includes a reinforcement located in the region of the bladder (60) facing the cover (24).

[0059] Clause 6. The device (33) according to any one of Clauses 1-5, wherein, when the bladder (60) is inflated, the size of the bladder (60) is set to completely fill the mold cavity (48).

[0060] Clause 7. The apparatus (33) pursuant to any one of Clauses 1-6 further includes:

[0061] The controller (84) is configured to coordinate the operation of the press (40) with the inflation of the bladder (60).

[0062] Clause 8. A method for forming a wrinkle-reducing molded composite cap stringer (20), comprising:

[0063] By forcing the composite material (56) into the mold cavity (48), the composite material (56) is formed into a molded cap-shaped portion (22) having sides and a cap (24); and

[0064] When forming the composite charge (56), the stress (62) in the cover (24) during forming is reduced by constraining the cover (24).

[0065] Clause 9. The method described in Clause 8 further includes:

[0066] The composite charge (56) is placed on a pair of molds (42), and

[0067] The process of forcing the composite charge (56) into the mold cavity (48) includes using a stamping press (40) to press the composite charge (56) into the mold cavity (48) while simultaneously constraining the cover (24).

[0068] Clause 10. The method described pursuant to Clause 9 further includes:

[0069] When the composite charge (56) is pressed into the mold cavity (48), pressure (64) is applied to the side (26) of the cap-shaped portion (22) using the mold (42).

[0070] Clause 11. The method described pursuant to Clause 9 or 10 further includes:

[0071] The hat-shaped portion (22) is shaped along its length.

[0072] Clause 12. The method according to any one of Clauses 8-11, wherein the restraining cover (24) comprises:

[0073] Inflate the sac (60) with air, and

[0074] Force (64) is applied to the cover (24) using a bladder (60).

[0075] Clause 13. The method according to Clause 12, wherein the capsule (60) is inflated before the composite charge (56) is forced into the mold cavity (48).

[0076] Clause 14. The method according to any one of Clauses 8-13, wherein,

[0077] The forming of the cap-shaped portion (22) includes a region along the length of the cap-shaped portion (22), wherein the forming generates stress (62) in the cap portion (24) along this region, and

[0078] Reducing stress (62) in the cover (24) includes sweeping (66) the stress (62) from the cover (24) in that region to other areas of the cap-shaped portion (22).

[0079] Clause 15. A method for forming a molded composite cap-shaped stringer (20) having a cap-shaped portion (22), the cap-shaped portion including a side portion (26) and a cap portion (24), comprising:

[0080] The flat composite charge (56) is placed on a pair of molds (42) that define the mold cavity (48);

[0081] The flat composite charge (56) is forced into the mold cavity (48) to form a cap-shaped portion (22) of the stringer (20) having a side (26) and a cover (24);

[0082] The molding die cavity (48); and

[0083] Wrinkles in the cap (24) during the formation of the cap-shaped portion (22) are reduced by transferring the stress (62) in the cap (24) away from the cap (24) (66).

[0084] Clause 16. The method according to Clause 15, wherein reducing wrinkles in the cover (24) includes restraining (64) the cover (24).

[0085] Clause 17. The method according to Clause 15 or 16, wherein transferring stress (62) away from the cover (24) comprises: applying pressure (64) to the cover (24) from within the mold cavity (48).

[0086] Clause 18. The method according to any one of Clauses 15-17, wherein molding is performed before the flat composite charge (56) is forced into the mold cavity (48).

[0087] Clause 19. The method according to any one of Clauses 15-18, wherein molding is performed after the flat composite charge (56) is forced into the mold cavity (48).

[0088] Clause 20. The method according to any one of Clauses 15-19, wherein applying pressure (64) to the cover (24) is performed by:

[0089] Inflate the bladder (60) inside the mold cavity (48), and

[0090] Use a sac-like object (60) to apply force (64) to the cover (24).

[0091] Various illustrative examples have been presented for purposes of explanation and description, and are not intended to be exhaustive or limiting to the examples disclosed. Many variations and modifications will be apparent to those skilled in the art. Furthermore, different illustrative examples may offer different advantages compared to other illustrative examples. In order to best explain the principles, practical applications, and enable others skilled in the art to understand the disclosure of various examples with various modifications suitable for the intended particular purpose, one or more selected examples have been chosen and described.

Claims

1. An apparatus (33) for manufacturing a molded composite cap-shaped stringer (20), comprising: A pair of molds (42) are configured to be formed along the length and define a mold cavity (48), into which a flat composite material (56) can be formed to form a shaped cap portion (22) having a cover (24). A stamping press (40) is configured to form the composite charge (56) into the mold cavity (48); as well as A bladder (60) is located within the mold cavity (48) between the molds (42) and is configured to be positioned below the composite charge (56). When the bladder (60) is inflated, the bladder (60) is sized to completely fill the mold cavity (48), and the bladder (60) is configured to constrain the cap (24) when the shaped cap portion (22) is formed.

2. The apparatus (33) according to claim 1, wherein, The capsule (60) is formed of an elastomer.

3. The apparatus (33) according to claim 1 or 2, wherein, The capsule (60) has sufficient rigidity to constrain the cap (24) when forming the composite material (56).

4. The apparatus (33) according to claim 1 or 2, wherein, The capsule (60) includes a reinforcement located in the region of the capsule (60) facing the cover (24).

5. The apparatus (33) according to claim 1 or 2, further comprising: A controller (84) is configured to coordinate the operation of the press (40) with the inflation of the bladder (60).

6. A method for forming a wrinkle-reducing molded composite cap-shaped stringer (20), comprising: The flat composite charge (56) is placed on a pair of molds (42) that define the mold cavity (48); By using a stamping press (40) to press the composite material (56) into the mold cavity (48), the composite material (56) is forced into the mold cavity (48), and the composite material (56) is formed into a shaped cap-shaped portion (22) having a side and a cover (24). Inflate the bladder (60) placed in the mold cavity (48) and apply force (64) to the cover (24) using the bladder (60). During the forming of the composite charge (56), the stress (62) in the cover (24) is reduced during forming by constraining the cover (24).

7. The method of claim 6, further comprising: When the composite charge (56) is pressed into the mold cavity (48), pressure is applied to the side (26) of the cap-shaped portion (22) using the mold (42).

8. The method according to claim 6 or 7, further comprising: The hat-shaped portion (22) is shaped along its length.

9. The method according to claim 6, wherein, The capsule (60) is inflated before the composite charge (56) is forced into the mold cavity (48).

10. The method according to any one of claims 6 to 7, wherein, Forming the cap-shaped portion (22) includes shaping a region along the length of the cap-shaped portion (22), wherein this formation generates stress (62) in the cap portion (24) along the region, and Reducing the stress (62) in the cover (24) includes sweeping (66) the stress (62) from the cover (24) in the region to other regions of the cap-shaped portion (22).

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