Stringer forming apparatus and method

Abstract

To provide equipment and processes for making composite laminate parts, and particularly an apparatus and method for making composite laminate stringers having various shapes.SOLUTION: Composite laminate stiffeners such as stringers are punch-formed between first and second universal dies respectively carried on first and second trays. The second tray is mounted for sliding movement relative to the first tray between a punch position and a compaction position. Parts of the first and second dies are easily reconfigurable, allowing different shapes of stiffeners to be formed on the same forming apparatus.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure broadly relates to forming stringers such as those used for reinforcing aircraft structures, and more particularly to stringer forming apparatuses and methods.

Background Art

[0002] Composite material stringers, such as those used in the aircraft and marine industries, can be produced by compressing a flat stack of composite material plies between a pair of tool dies disposed within a press or similar device that co-compresses the dies. Each die has a unique tool surface configured to produce a specific cross-sectional stringer shape. Thus, each stringer requires the use of a die specific to its shape and cannot be used to produce stringers having other shapes. Dies can be expensive to manufacture, resulting in significant costs when various sets of dies are required to produce various stringer shapes.

[0003] Manufacturing stringers having various shapes can also be costly because it takes time and effort to change the dies within the press. For some types of stringers, it is necessary to change die components specific to certain processing stages, such as densification of portions of the stringer after forming the shape of the stringer. The need to change die components adds additional expense to the stringer manufacturing process.

[0004] Therefore, it is desirable to provide a stringer forming apparatus and related method that reduces the need for dies and die components of specific configurations required to produce various stringer shapes. It is also desirable to reduce the time and effort required to change the forming apparatus to produce various forms of stringers.

Summary of the Invention

[0005] This disclosure broadly relates to equipment and processes for manufacturing composite laminated components, and more particularly to apparatus and methods for manufacturing composite laminated stringers having various shapes.

[0006] According to one embodiment, a reconfigurable pallet is provided for forming composite stringers having various shapes. The pallet includes an upper support and a lower support configured to move toward and away from each other. The pallet also includes an upper die including a punch. The upper die is detachably mounted on the upper support and configured to allow the upper die to be replaced with a different upper die. The pallet further includes a lower die mounted on the lower support. The lower die includes a die block assembly that forms a die cavity in which a composite charge may be formed by the punch.

[0007] In another embodiment, an apparatus is provided for punching a composite material charge into a stringer. The apparatus includes a pair of upper arms and a pair of lower arms. The apparatus also includes an upper tray coupled to the upper arms. The upper tray includes an upper plate and a punch. The apparatus includes a lower tray which includes a die having a die cavity in which the punch may form a composite material charge into a stringer shape. The apparatus further includes a sliding assembly which mounts the lower tray on the lower arms so that it slides between a first position in which the punch forms the composite material charge in the die cavity and a second position in which the composite material charge is compacted using the upper plate.

[0008] In yet another embodiment, a method for forming a composite stringer is provided. The method includes placing a flat composite charge between a first die and a second die, and moving the second die to a punch-forming position aligned with the first die. The method also includes a punch for forming the flat composite charge into the shape of a stringer while the second die is in the punch-forming position. The method includes shifting the second die from the punch-forming position to a consolidation position, and consolidating at least a portion of the stringer using the first die while the second die is in the consolidation position.

[0009] One advantage of the apparatus and method of this disclosure is that the time and effort required to compact composite stringers can be reduced. Another advantage is that a universal die is provided that can be easily and quickly reconfigured to produce stringers with various cross-sectional shapes. A further advantage is that the die change process is partially automated, thereby reducing labor costs and increasing throughput.

[0010] These features and functions may be implemented individually in various embodiments of this disclosure, or in combination in yet another embodiment. Further details of these embodiments can be understood by referring to the following description and drawings.

[0011] Novel features that may be considered characteristics of exemplary embodiments are described in the appended claims. However, exemplary embodiments, as well as preferred modes of use, further purposes, and their descriptions will be best understood by reading the following detailed description of exemplary embodiments of this disclosure with reference to the accompanying drawings. [Brief explanation of the drawing]

[0012] [Figure 1] This is a perspective view of the airplane. The position of the Stringa is indicated by a dashed line. [Figure 2] This is a perspective view of Stringa. [Figure 3]Figure 2 is an end view of the stringer. [Figure 4] This is an end view of another form of Stringa. [Figure 5] Figures 5-7 show a toolset diagram illustrating the sequential steps for forming a flat composite charge on the stringer shown in Figures 2 and 3. [Figure 6] Figures 5-7 show a toolset diagram illustrating the sequential steps for forming a flat composite charge on the stringer shown in Figures 2 and 3. [Figure 7] Figures 5-7 show a toolset diagram illustrating the sequential steps for forming a flat composite charge on the stringer shown in Figures 2 and 3. [Figure 8] This is a block diagram of a forming apparatus used to manufacture composite stringers. [Figure 9] Figures 9 and 10 are perspective views of the molding apparatus shown in Figure 8. Specific parts are not shown for clarity. [Figure 10] Figures 9 and 10 are perspective views of the molding apparatus shown in Figure 8. Specific parts are not shown for clarity. [Figure 10A] This is a perspective view of the lower die, showing the vacuum clamping feature integrated into the die block adapter. [Figure 11] This is a perspective view of the upper arm and upper tray. [Figure 11A] This is a front elevation view of a portion of the upper tray, including the upper die. [Figure 12] This is a perspective view of the lower arm and lower tray. [Figure 13] This is a perspective view showing how the lower plate is rotatably attached to the lower arm. [Figure 14] This is one of the diagrams of the upper pivot. [Figure 15] These are perspective views of two of the lower pivots. [Figure 16] This is a perspective view of the drive motors. The cover has been removed from one of the drive motors to reveal the pinion gear. [Figure 17] It is an end view of a forming apparatus showing the lower tray at its forming position. [Figure 18] It is a view showing a lower tray that is similar to FIG. 17 but is shifted laterally to its consolidation position. [Figure 19] It is a block diagram roughly showing the components of a system for controlling the operation of a forming apparatus. [Figure 20] It is a flowchart of a method for manufacturing a stringer. [Figure 21] It is a flowchart of an aircraft manufacturing and maintenance method. [Figure 22] It is a block diagram of an aircraft.

Embodiments for Carrying Out the Invention

[0013] The disclosed embodiments relate to methods and apparatuses for manufacturing composite reinforcements such as stringers used in the aircraft industry, the marine industry, and the like. For example, referring to FIG. 1, an aircraft 30 includes a fuselage 32, wings 34, and a tail including a vertical stabilizer 36 and a horizontal stabilizer 38. Each of these airframe components includes a composite outer skin 35 reinforced and stabilized by stringers 44 under the outer skin 35. The stringers 44 are typically joined to the IML (Inner Mold Line) of the outer skin 35 by co-curing or co-bonding. The stringers 44 may have any of various cross-sectional shapes depending on the application. One example of a stringer 44, often called a blade stringer, is shown in FIGS. 2 and 3. The blade stringer 44 includes a base 46 formed by an outwardly extending flange and a blade 48, often called a web. Another example of a stringer 44a, generally known as a round hat stringer 44a, is shown in FIG. 4. The hat stringer 44a includes a round hat section 52 and a pair of outwardly extending flanges 46. Using the disclosed methods and apparatuses, any of various other types of stringers can be fabricated, such as stringers 44, 44a, and, without limitation, I, J, Y, Z stringers, and other forms of hat stringers.

[0014] Depending on the application, stringer 44 may have various out-of-plane features, such as undulations, pad-ups, and / or joggles (not shown), at one or more positions along its length. The undulations of stringer 44 often need to match the undulations of the outer panel 35 to which stringer 44 is attached. For example, as shown in FIG. 2, stringer 44 has undulations 45 along its entire length in the XZ plane within the coordinate system shown at 50, although in other embodiments, stringer 44 may have straight sections along its length as well as local undulations. Stringer 44 may also have one or more undulations along its length in the XY plane. Each of base 46 and blade 48 may have variable thickness at one or more positions along their lengths to conform to local features of the structure to which stringer 44 is attached.

[0015] Next, attention is drawn to FIGS. 5 - 7. FIGS. 5 - 7 schematically illustrate a process for forming a flat multi-ply composite charge 64 into stringer 44 or a similar reinforcement of the type described above. In this embodiment, the stringer 44 being formed is a blade stringer 44, although any of various other types of stringers can be formed using the principles described below. Referring to FIG. 5, a tool set 54 for compression-forming charge 64 into a stringer shape generally includes an upper die 55 and a lower die 57. The upper die 55 includes a punch 62 attached to an upper plate 56, while the lower die 57 includes a pair of die blocks 60 that form a die cavity 70 that is slidable 74 toward and away from each other on a lower plate 58. Both the upper plate 56 and the lower plate 58 are formed of a flexible material, such as a flexible metal or composite, while die blocks 60 and punch 62 are divided into several segments along their lengths to allow them to flex.

[0016] When in use, with the upper die 55 lifted above the lower die 57, a flat multiply composite charge 64 is positioned between the upper die 55 and the upper surface of the die block 60. The upper plate 56 is then moved downward by a force F, causing the punch 62 to compress or "punch" the charge 64 into the die cavity 70, thereby forming a pair of web portions 68. While the web portions 68 of the stringer 44 are formed by the punch 62, the flange portion 66 of the stringer 44 is constrained but allowed to slide between the upper plate 56 and the die block 60.

[0017] Next, as shown in Figure 6, the upper plate 56 is removed and replaced with a flat plate 56a. Then, as shown in Figure 7, a force F is applied to the flat plate 56a. The flat plate 56a restrains the flange portions 66 while the die blocks 60 are pressed together toward each other, and folds the web portions 68 toward each other to form the blade 48 while the flange portions 66 are pulled together to form the base 46 of the stringer 44. Finally, the flat plate 56a is removed, and the die blocks 60 are pulled apart, allowing the stringer 44 to be removed from the tool set 54. The stringer 44 may be undulated along its length in the XY and / or XZ planes (Figure 2) by undulating the tool set 54 using appropriate equipment (not shown).

[0018] Next, please turn your attention to Figures 8 to 10A. Figures 8 to 10A show a forming apparatus 76 for forming a flat composite charge 64 into a stringer 44 using a punch forming process similar to that described above in relation to Figures 5 to 7. As will be described in more detail below, the forming apparatus 76 is a reconfigurable pallet and end effector employing universal dies. They can be easily adapted to form any of a wide variety of stringer shapes with simple modifications that can be performed easily and quickly. The forming apparatus 76 broadly comprises an upper support 82a and a lower support 82b, each including an upper arm 78 and a lower arm 80. The supports 82a and 82b are coupled to one or more drive mechanisms (not shown) that move the arms 78 and 80 toward and away from each other along the Z axis.

[0019] The forming apparatus 76 further comprises an upper tray 84 having an upper die 55, and a lower tray 86 having a lower die 57. The upper tray 84 is connected to an upper arm 78 by a plurality of upper pivots 88. The plurality of upper pivots 88 allow the upper tray 84 to bend as required in the XZ plane (Figure 2). Each of the upper pivots 88 includes a removable pivot pin 89 (Figure 10). The removable pivot pins 89 detachably attach the upper tray 84 to the upper arm 78. The upper tray 84 includes a flexible upper plate 56 and a punch 62. The punch 62 functions similarly to the punch described above in relation to Figures 5-7. Although not shown in the drawings, the punch 62 may be segmented along its length to allow it to flex.

[0020] The upper tray 84 further includes an inflatable clamping hose 102 that applies pressure to the composite charge 64 via a pair of laterally spaced cowl plates 63 positioned on either side of the punch 62. The cowl plates 63 function to apply clamping pressure evenly to the composite charge 64 and also act as a heat sink to evenly distribute the heat applied to the composite charge 64 by heating a blanket 65 sandwiched between the cowl plates and the hoses 104. Referring to Figure 11A, the pair of vertically aligned hoses 104, the cowl plates 63, and the heat blanket 65 may be arranged as a laminated subassembly 117 on either side of the punch 62. The subassembly 117 may be attached to the upper plate 56 by any suitable means.

[0021] The lower tray 86 is pivotably connected to the lower arm 80 by a plurality of lower pivots 90. The lower tray 86 is detachably connected to the adapter arm 108 by a removable pivot pin 91. The lower tray 86 includes a reconfigurable die block assembly 71 to allow the formation of various stringer shapes. The die block assembly 71 includes a plurality of die blocks 60 slidably mounted on a flexible lower plate 58. The die block assembly 71 further includes a cap assembly 72. The cap assembly 72 includes a die block adapter 98. The die block adapter 98 covers the die block 60 and is detachably mounted to the die block 60. The die block adapter 92 has a tool surface that partially determines the cross-sectional shape of the formed stringer 44. In some applications, depending on the shape of the formed stringer, it would be desirable to clamp a portion of a composite charge, such as a flange, to the die block adapter 92. Thus, the lower die 57 may optionally include vacuum clamping capability. In this case, one or more air inlet openings 119 are provided at the top of each die block adapter 92, with a vacuum port 121 connected to its side. The vacuum port 121 is connected to a vacuum source 125 (Figure 19) via a hose (not shown). The vacuum source 125 draws a vacuum at the air inlet opening 119, drawing down the composite material charge 64 and clamping it against the top of the die block adapter 92.

[0022] The die block 60 includes an egg-shaped cooling passage 93, which allows for cooling of the die block assembly 71 by either convection or forced air. The die blocks 60 may be constrained together using rods or cables (neither shown), which pass through circular holes 75 within the die blocks. The circular holes 75 may function to dissipate heat from the die blocks 60. An inflatable block separation hose 107 is positioned between the die blocks 60 and acts as a barrier or stop to maintain a minimum separation distance between the die blocks 60, thus preventing the punch 62 from unintentionally contacting the top of the die block adapter 92 when the upper die 55 is lowered toward the lower die 57 during the forming operation.

[0023] Referring to Figures 11 and 14, the upper plate 56 is formed from a flexible material such as flexible metal or flexible composite. The upper pivot plate 110 is fixed to the upper plate 56 and is pivotably connected to the upper arm 96 via the upper pivot 88. The upper pivot plate 110 is also guided by a roller assembly 112. The roller assembly 112 allows the upper pivot plate 110 and the upper plate 56 to move along the X axis relative to the upper arm 96, and thus allows the upper plate 56 to flex in the XZ plane as required to form the stringer 44 into the desired contours. As will be described below, the slidable connection formed between the upper pivot plate 110 and the roller 112 allows the upper plate 56 to be slidably attached to the upper arm 78, thereby enabling the assembly of the upper plate 56 and the punch 62 to be removed from the forming apparatus 76 by sliding the upper plate 56 along the X-axis until the upper pivot plate 110 is separated from the roller 112. Thus, the upper die 55 can be removed and replaced with an upper die 55 configured differently, either by removing the pivot pin 89 or by sliding the upper plate 56 along the roller 112.

[0024] Next, please refer to Figures 12, 13, and 15. Figures 12, 13, and 15 show further details of the lower tray 86. The lower guide 94 and the core block 60 are each fixed to the lower plate 58. The die block adapter 92 is detachably attached to the die block 60 by fasteners such as screws and is spaced apart from each other to form the die cavity 70 in which the composite material charge 64 (Figure 8) is formed by the punch 62. As is best seen in Figure 15, the lower pivot plate 118 is fixed to the bottom of the lower plate 58. The lower pivot 90 swivels the lower pivot plate 118 to the top of the adapter arm 108. The adapter arm 108 is fixed to the lower adapter base 116. The adapter arm 108 is mounted on the lower adapter base 116. The lower pivot plate 118 is supported on the roller 114. The roller 114 allows the lower plate 58 to move along the X direction while the undulations of the stringer 44 are being formed.

[0025] The lower adapter base 116 is mounted on a linear guide 99. The linear guide 99 slides along a tray rail 97 on a lower arm 80. The linear guide 99 and the tray rail 97 form a sliding assembly. The sliding assembly allows the lower tray 86 to move along the Y-axis between two operating positions described below. See also Figure 16, the lower tray 86 is shifted laterally between these two operating positions by a motor drive 100. Each of the motor drives 100 comprises a suitable gas-pneumatic, hydraulic, or electric motor 101 that drives a pinion gear 120. The pinion gear 120 engages with a toothed rack 122 on one of the lower arms 80. Each of the motors 101 includes a motor housing 123 which is fixed to one of the lower adapter bases 116 by screws (not shown) or other means.

[0026] As described above, the lower tray 86 can be shifted by the motor drive 100 along the lower arm 80 in a linear manner. Figure 17 shows the lower tray in the punch position 87 at the outer end of the lower arm 80. In this case, the upper die 55 is aligned above the lower die 57, and in particular, the punch 62 is aligned vertically above the die cavity 70. In this embodiment, the punch 62 is a blade that punches a flat composite charge into the die cavity 70 in a process step similar to that described above in relation to Figure 5. In this case, the upper die 55 and the lower die 57 are closed to form a pair of flange portions 66 and web portions 68. After this initial forming step, the upper arm 78 is shifted upward, thereby lifting the upper tray 84 and withdrawing the punch 62 from the die cavity 70.

[0027] Referring to Figure 18, with the upper tray 84 shifted upward to withdraw the punch 62 from the die cavity 70, the motor drive 100 is activated and shifts the entire lower tray 86 to the left to the consolidation position 95, as seen in Figure 18. In that position, the upper plate 56 is positioned directly above the die block adapter 92. In the consolidation position 95, the upper arm 78 is lowered so that the upper plate 56 comes into contact with the flange portion 66 of the composite charge 64, similar to the process described above in relation to Figure 6, thereby allowing the flange portion 66 to be consolidated.

[0028] The operation of the forming apparatus 76 can be controlled using various control systems. For example, referring to Figure 19, one suitable control system comprises a controller 138, such as a PC or a programmable controller. It controls the operation of the motor drive 100, the vacuum source 125, the compressed air supply source 136, and the die block heating / cooling system 140.

[0029] Next, referring to Figures 8-10, 17, and 18, the process of forming the composite charge 64 into the stringer 44 when used begins by setting up an upper tray 84 having a punch 62 of the desired tool shape and a die block adapter 92 of the desired shape in the die block 60. The shapes of the punch 62 and the die block adapter 92 determine the cross-sectional shape of the stringer 44 that is formed. Next, with the lower tray 86 in the punch position 87 shown in Figure 17, the upper arm 78 is lifted enough to allow the flat composite charge 64 to be placed on the upper surface of the die block adapter 92. The hose 106 is pressurized and moved away from the die block 60, forming a die cavity 70 of the desired width. Then, the hose 106 is depressurized, while both hoses 102 and 104 are pressurized at a controlled rate. The upper arm 78 moves downward, the cowl plate 63 comes into contact with the composite charge 64, and a desired amount of pressure is applied to the composite charge 64.

[0030] The continuous downward movement of the upper arm 78 causes the punch 62 to form a composite charge 64 inside the die cavity 70. Meanwhile, the flange portion 66 of the charge 64 is constrained but is able to slip between the cowl plate 63 and the top of the die block adapter 92. The pressure inside the hose 104 is gradually reduced as the punch 62 moves downward, allowing the die block 60 to move away as the punch 62 forms the composite charge 64 inside the die cavity 70.

[0031] Next, the upper arm 78 is moved upward, causing the punch 62 to be withdrawn from the die cavity 70. Then, the motor drive 101 is activated, moving the entire lower tray 86 along the Y-axis from the punch position 87 shown in Figure 17 to the consolidation position 95 shown in Figure 18. At the consolidation position 95, the lower tray 86 is no longer vertically aligned with the punch 62, but instead vertically aligned with the upper plate 56. The upper arm 78 is again moved downward until the upper plate 56 contacts the flange portion 66 of the partially formed charge 64. While the upper plate 56 applies consolidation pressure to the flange portion 66, the pressure in the hose 104 is increased, moving the die block 60 and cap assembly 72 toward each other. It compresses and folds the web portion 68 of the composite charge 64, similar to the process steps described above in relation to Figure 7. In several embodiments where the stringer 44 is undulated along its length (see Figure 2), a die changing mechanism (not shown) bends the punch 62 and the die block 60 and cap assembly 72, thereby forming the stringer 44 into the desired undulation. Once the stringer 44 is fully formed and compacted, the hose 104 is deflated, the upper arm 78 lifts the upper tray 84, and the hose 106 is inflated. This allows the die block 60 and cap assembly 72 to move away from each other, enabling the stringer 44 to be removed from the forming apparatus 76.

[0032] Next, please look at Figure 20. Figure 20 roughly illustrates the steps of a method for producing a composite stringer 44 that can be carried out using the forming apparatus 76 described above. Starting at 142, a flat composite charge 64 is placed between the first die 55 and the second die 57. At 144, the second die 57 is moved to a punch-forming position 87 that aligns with the first die 55. At 146, the composite charge 64 is punch-formed into the shape of a stringer 44 while the second die 57 is in the punch-forming position 87. The composite charge 64 is formed in the die cavity 70 within the second die 57 using the punch 62 of the first die. At 148, the second die 57 is shifted from the punch-forming position 87 to a consolidation position 95. At 150, at least a portion 68 of the stringer 44 is compacted using the first die 55 while the second die 57 is in the compaction position 95.

[0033] Multiple embodiments of this disclosure may be used in a variety of potential applications, particularly in the transportation industry (including, for example, aerospace, marine, and other applications where composite reinforcements such as composite laminated stringers for aircraft may be used). Therefore, referring now to Figures 21 and 22, embodiments of this disclosure may be used in the context of an aircraft manufacturing and maintenance method 152 as shown in Figure 21, and an aircraft 154 as shown in Figure 22. Applications of the aircraft in multiple embodiments of this disclosure may include various composite stringers of various cross-sectional shapes, including those having undulations, curvatures, varying thicknesses, or other non-uniformities along their length. In the pre-manufacturing stage, exemplary method 152 may include specification and design 156 of the aircraft 154 and procurement of materials 158. In the manufacturing stage, manufacturing 160 of the components and subassemblies of the aircraft 154 and system integration 162 are carried out. The aircraft 154 may then undergo authorization and delivery 164 for operation 166. While in customer operation, the aircraft 154 is scheduled for routine maintenance and upkeep 168, which may include modifications, reconfigurations, and refurbishments.

[0034] Each process of Method 152 may be performed or carried out 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 major system subcontractors; a third party may include, but is not limited to, any number of vendors, subcontractors, and suppliers; and an operator may be an airline, leasing company, military organization, service organization, etc.

[0035] As shown in Figure 22, an aircraft 154 manufactured by exemplary method 152 may include a fuselage 170 with multiple systems 172 and interior 174. Examples of high-level systems 172 include one or more of the following: propulsion systems 176, electrical systems 178, hydraulic systems 180, and environmental systems 182. Any number of other systems may be included. Although examples from the aerospace industry are shown, the principles of this disclosure may also be applicable to other industries such as the marine and automotive industries.

[0036] The apparatus and methods implemented herein may be employed during any one or more of the stages of the aircraft manufacturing and maintenance method 152. For example, components or subassemblies corresponding to the manufacturing process 160 may be manufactured or produced during the operation of the aircraft 154 in the same manner as the components or subassemblies are manufactured. Furthermore, one or more embodiments of apparatus, embodiments of methods, or combinations thereof may be used in manufacturing stages 160 and 162, for example, by substantially streamlining the assembly of the aircraft 154 or by reducing the cost of the aircraft 154. Similarly, one or more embodiments of apparatus, embodiments of methods, or combinations thereof may be used during the operation of the aircraft 154 in maintenance and servicing 168, for example, but not limited to.

[0037] Where used herein, the expression “at least one of the listed items” means that one or more different combinations of the listed items may be used, and only one of each listed item may be required. For example, “at least one of item A, item B, and item C” may, non-limitingly, include 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. An item can be a specific object, thing, or category. In other words, “at least one of the listed items” means that any combination of items, and several items, may be used from the listed items, but not all of the listed items are required.

[0038] Furthermore, this disclosure includes embodiments as defined below. Article 1. A reconfigurable pallet (76) for forming composite stringers (44) having various shapes, upper support (82a), An upper die (55) including a punch (56), which is detachably attached to the upper support (82a) and configured to allow the upper die (55) to be replaced with a different upper die (55), A lower support (82b), wherein the upper support (82a) and the lower support (82b) are configured to move toward and away from each other, and A reconfigurable pallet comprising a lower die (57) mounted on a lower support (82b), the lower die (57) including a die block assembly (71) that forms a die cavity (70) in which a composite material charge (64) may be formed by the punch (56). Article 2. The upper support (82a) includes an upper arm (78), The die block assembly (71) is reconfigurable to allow various stringer shapes to be formed. The upper die (55) includes an upper tray (84) having an upper plate (62), The punch (56) is attached to the upper plate (62) in the reconfigurable pallet as described in Clause 1. Article 3. The reconfigurable pallet according to Clause 2, further comprising an upper pivot (88) that pivotably attaches the upper plate (62) to the upper arm (78), wherein the upper pivot (88) includes a removable pivot pin (89) that allows the upper plate (62) to be removed from the upper arm (78). Article 4. A reconfigurable pallet according to Clause 2, further comprising a sliding connection (85) for attaching the upper tray (84) to the upper arm (78) so as to be slidable, the sliding connection (85) being configured to allow the upper tray (84) to be released from the upper arm (78) and replaced with an upper tray (84) configured in a different manner. Article 5. The lower support (82a) includes a lower arm (80), The reconfigurable pallet according to Clause 1, wherein the lower die (57) includes a lower tray (86) on which the die block assembly (71) is mounted. Article 6. The reconfigurable pallet according to Clause 5, further comprising a lower pivot (90) for pivotably mounting the lower tray (86) onto the lower arm (80). Article 7. The reconfigurable pallet according to Clause 5, wherein the lower tray (86) is slidably mounted on the lower arm (80) for movement between a stringer forming position (87) and a stringer compaction position (95). Article 8. The reconfigurable pallet according to Clause 7, further comprising a motor drive (100) supported by the lower arm (80) and configured to drive the lower tray (86) along the lower arm (80) between the stringer forming position (87) and the stringer compaction position (95). Article 9. The die block assembly (71) is Die blocks (60) that can be shifted toward and away from each other, and The reconfigurable pallet according to Clause 1, comprising the die block (60) and a die block adapter (98) that is detachably attached and configured to allow the lower die (57) to be reconfigured to form stringers (44) of various shapes. Article 10. An apparatus for punching a composite material charge (64) onto a stringer (44), A pair of upper arms (78), An upper tray (84) coupled to the upper arm (78), the upper tray (84) including an upper plate (62) and a punch (56), A pair of lower arms (80), The lower tray (86) includes a die (57) having a die cavity (70) in which the punch (56) can form the composite material charge (64) in a stringer shape, and The apparatus includes a sliding assembly (85) that mounts the lower tray (86) on the lower arm (80) such that the punch (56) slides between a first position (87) in which the punch (56) forms the composite material charge (64) in the die cavity (70) and a second position (95) in which the upper plate (62) compacts the composite material charge (64). Article 11. The aforementioned sliding assembly (85) The apparatus according to Clause 10, comprising rails (97) extending along the lower arm (80), and linear guides (99), each being mounted to move along the rail (97) and coupled to the lower tray (86). Article 12. The apparatus according to clause 10, further comprising a pivot (88) connecting the upper tray (84) to the upper arm (78), the pivot (88) being configured to allow the upper tray (84) to pivot relative to the upper arm (78). Article 13. The apparatus according to clause 10, further comprising a pivot (90) connecting the lower tray (86) to the lower arm, the pivot (90) being configured to allow the lower tray to pivot relative to the lower arm (80). Article 14. The upper tray (84) is The first section (55) to which the punch (56) is attached, and The apparatus according to Clause 10, comprising a second section (56) adjacent to the first section (55) and spaced apart from the first section (55), the second section (56) configured to engage with a portion of the stringer (44) and to compact a portion of the stringer (44). Article 15. The lower die (57) is Plate (58), A die block (60) is mounted on the plate (58), and The apparatus according to Clause 10, comprising a die block adapter (98) attached to the die block (60), having a tool surface for forming the composite material charge (54) within the die cavity (70), the die block adapter (98) being removable and configured to be replaced by any of a plurality of die block adapters (98) having differently configured tool surfaces. Article 16. A method for forming a composite stringer (44), A flat composite charge (64) is placed between the first die (55) and the second die (57). Moving the second die (57) to a punch forming position (87) aligned with the first die (55), Punching the flat composite charge (64) into the shape of a stringer (44) while the second die (57) is in the punching position (87), comprising using the punch (56) of the first die (55) to press the flat composite charge (64) into the die cavity (70) in the second die (57), Shifting the second die (57) from the punch forming position (87) to the compaction position (95), and A method comprising using the first die (55) to compact at least a portion of the stringer (44) while the second die (57) is in the compaction position (95). Article 17. The method according to Clause 16, wherein shifting the second die (57) includes moving the second die (57) laterally so as to be out of alignment with the first die (55). Article 18. The method according to clause 17, wherein moving the second die (57) includes using a motor drive (100) to slide the second die (57) along a rail (97). Article 19. The first die (55) is detachably attached to the support (82a), The first die (55) is released from and removed from the support (82a), and The method according to Clause 16, further comprising replacing the first die (55) with a third die, the third die being detachably attached to the support (82a). Article 20. The method according to clause 16, further comprising causing the first die (55) and the second die (57) to undulate by rotating them.

[0039] The descriptions of the various embodiments are presented for illustrative and explanatory purposes only and are not intended to be exhaustive or to limit the embodiments to the disclosed forms. Many modifications and variations will be apparent to those skilled in the art. Furthermore, different embodiments may offer different features from other embodiments. One or more selected embodiments are chosen and described to best illustrate the principles and practical applications of those embodiments and to enable others skilled in the art to understand the various modifications suitable for specific applications envisioned in conjunction with the disclosure of the various embodiments.

Claims

1. An apparatus for punching a composite material charge (64) onto a stringer (44), A pair of upper arms (78), An upper tray (84) coupled to the upper arm (78), the upper tray (84) including an upper plate (62) and a punch (56), A pair of lower arms (80), The lower tray (86) includes a lower die (57) having a die cavity (70) in which the punch (56) can form the composite material charge (64) in a stringer shape within the die cavity (70), and The apparatus includes a sliding assembly (85) that mounts the lower tray (86) on the lower arm (80) such that the punch (56) slides between a first position (87) in which the punch (56) forms the composite material charge (64) in the die cavity (70) and a second position (95) in which the upper plate (62) compacts the composite material charge (64).

2. The sliding assembly (85) is The apparatus according to claim 1, comprising a plurality of rails (97) each extending along the lower arm (80), and a plurality of linear guides (99), each of which is mounted to move along the plurality of rails (97) and coupled to the lower tray (86).

3. The apparatus according to claim 1 or 2, further comprising a pivot (88) connecting the upper tray (84) to the upper arm (78), the pivot (88) being configured to allow the upper tray (84) to pivot relative to the upper arm (78).

4. The apparatus according to claim 1, further comprising a pivot (90) connecting the lower tray (86) to the lower arm (80), the pivot (90) being configured to allow the lower tray (86) to pivot relative to the lower arm (80).

5. The upper tray (84) is The first section (55) to which the punch (56) is attached, and The apparatus according to claim 1, comprising a second section (56) adjacent to the first section (55) and spaced apart from the first section (55), the second section (56) being configured to engage with a portion of the stringer (44) and to compact a portion of the stringer (44).

6. The lower die (57) is Plate (58), A die block (60) is mounted on the plate (58), and The apparatus according to claim 1, comprising a die block adapter (98) attached to the die block (60), having a tool surface for forming the composite material charge (54) within the die cavity (70), wherein the die block adapter (98) is configured to be removable and replaceable by any of a plurality of die block adapters (98) having differently configured tool surfaces.

7. A method for forming a composite material stringer (44), A flat composite material charge (64) is placed between the first die (55) and the second die (57). Moving the second die (57) to a punch forming position (87) aligned with the first die (55), Punching the flat composite material charge (64) into the shape of a stringer (44) while the second die (57) is in the punching position (87), comprising using the punch (56) of the first die (55) to press the flat composite material charge (64) into the die cavity (70) in the second die (57), Shifting the second die (57) from the punch forming position (87) to the compaction position (95), and A method comprising using the first die (55) to compact at least a portion of the stringer (44) while the second die (57) is in the compaction position (95).

8. The method according to claim 7, wherein shifting the second die (57) includes moving the second die (57) laterally so as to be out of alignment with the first die (55).

9. The method according to claim 8, wherein moving the second die (57) includes sliding the second die (57) along a rail (97) using a motor drive (100).

10. The first die (55) is detachably attached to the support (82a), The first die (55) is released from and removed from the support (82a), and The method according to any one of claims 7 to 9, further comprising replacing the first die (55) with a third die, the third die being detachably attached to the support (82a).

11. The method according to claim 7, further comprising rotating the first die (55) and the second die (57) to create undulations in the first die (55) and the second die (57).

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