WO2004054734A1 - Procede et outil de fabrication d'element d'aeronef - Google Patents

Procede et outil de fabrication d'element d'aeronef Download PDF

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Publication number
WO2004054734A1
WO2004054734A1 PCT/GB2003/005455 GB0305455W WO2004054734A1 WO 2004054734 A1 WO2004054734 A1 WO 2004054734A1 GB 0305455 W GB0305455 W GB 0305455W WO 2004054734 A1 WO2004054734 A1 WO 2004054734A1
Authority
WO
WIPO (PCT)
Prior art keywords
shape
shaped surface
component
aircraft component
aircraft
Prior art date
Application number
PCT/GB2003/005455
Other languages
English (en)
Inventor
Andrew Levers
Original Assignee
Bae Systems Plc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Bae Systems Plc filed Critical Bae Systems Plc
Priority to US10/539,017 priority Critical patent/US20060042347A1/en
Priority to CA002510154A priority patent/CA2510154A1/fr
Priority to AU2003288468A priority patent/AU2003288468A1/en
Priority to EP03780389A priority patent/EP1581356A1/fr
Publication of WO2004054734A1 publication Critical patent/WO2004054734A1/fr

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D26/00—Shaping without cutting otherwise than using rigid devices or tools or yieldable or resilient pads, i.e. applying fluid pressure or magnetic forces
    • B21D26/02—Shaping without cutting otherwise than using rigid devices or tools or yieldable or resilient pads, i.e. applying fluid pressure or magnetic forces by applying fluid pressure
    • B21D26/021—Deforming sheet bodies
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D37/00—Tools as parts of machines covered by this subclass
    • B21D37/02—Die constructions enabling assembly of the die parts in different ways

Definitions

  • the present invention relates to modifying the shape of an aircraft component, and in particular, but not exclusively to creep forming a metallic aircraft component so that it adopts a complex shape.
  • Portions of the metal wing skin of an aircraft may be manufactured with a creep forming process, wherein a portion of flat sheet material is caused to adopt the complex target shape of a given portion of the wing skin.
  • the wing skin component in generally flat form is, for a given length of time (generally several hours), forced against a forming surface of a creep forming tool.
  • the component undergoes creep and hardens by means of precipitation hardening.
  • the component skin springs back to a shape dependent on the complex shape of the forming surface.
  • the forming surface is so shaped that after spring back, the component adopts a shape substantially the same as that of the target shape.
  • creep forming components has its substantial advantages.
  • the present invention seeks to provide an improved apparatus and/or method for modifying the shape of an aircraft component.
  • an apparatus for modifying the shape of an aircraft component including a shaped surface so arranged that an aircraft component may be forced against the shaped surface in a manner that modifies the shape of the aircraft component, wherein the shaped surface is arranged so that its shape is adjustable.
  • the shaped surface being arranged so that its shape is adjustable, enables the apparatus to be built without needing to be very confident that the shaped surface has a shape such that it will be able to be used to produce components of the target shape, because the shape of the shaped surface may be readily adjusted if it transpires that the shaped surface is not able to produce a component of the correct, or target, shape (or to a shape that differs only within acceptable tolerances).
  • the adjustable apparatus of the present invention is particularly advantageous compared to a prior art creep forming tool with a forming surface having a fixed shape.
  • An example of such a prior art creep forming tool is illustrated by Figs. 1a and 1b, which show schematically a typical construction of a creep forming tool 101 , both before operation ( Figure 1a) and during creep forming of a component 104 ( Figure 1b).
  • the tool 101 includes a substantially solid base 102 on top of which there is permanently fixed (by welding) a forming surface 103 in the form of a shaped sheet of steel that is supported across substantially its entire surface by the base 102.
  • the shape of the forming surface 103 is calculated before manufacture of the tool 101.
  • the mathematical models available in the prior art are not reliable and it is often the case that the shape the forming surface 103 of the tool 101 is at least in certain regions incorrect. In such a case, the tool 101 may thereafter require substantial modification in order to correct the shape of the forming surface 103. Moreover, in many cases, the need to change the shape of the forming surface 103 in one region will require a change in the position or shape of a different region of the surface 103 and substantial modification of the structure of the tool 101. Attaining the correct shape of the forming surface 103 of the tool 101 may require more than one round of modifications to the tool 101 and to the shape of the forming surface 103.
  • the present invention also provides according to a second aspect of the invention, an apparatus for modifying the shape of an aircraft component, the apparatus including a shaped surface so arranged that an aircraft component may be forced against the shaped surface in a manner that modifies the shape of the aircraft component, wherein the apparatus further includes an intermediate member that in use receives and supports the component, is positioned between the shaped surface and the component, and deforms to a shape dependent on the shape of the shaped surface. Providing such an intermediate member, enables the apparatus to be more easily modified.
  • the tool of the prior art shown in Figures 1a and 1b is inflexible and also costly and difficult to modify.
  • the forming surface 103 of the tool 101 of the illustrated prior art must both support the component 104 whilst it is forced to conform to a particular shape and must also define the shape to which the component 104 is forced to conform.
  • the function of supporting the component whilst it is forced to conform to a particular shape is advantageously performed by the intermediate member, whereas the function of defining the shape to which the component is forced to conform is advantageously provided not by the intermediate member, but by the shaped surface of the apparatus.
  • the shaped surface of the apparatus need not therefore be completely solid across the surface closest to the component, in contrast to the construction of the tool 101 of the prior art illustrated in Figures
  • the apparatus of the first aspect of the invention may also further include an intermediate member that in use receives and supports the component, is positioned between the shaped surface and the component, and deforms to a shape dependent on the shape of the shaped surface.
  • the intermediate member is preferably simple to construct.
  • the intermediate member may be generally sheet-like in shape.
  • the intermediate member may have a constant thickness across the majority of its area.
  • the intermediate member may, prior to use of the apparatus, be substantially flat.
  • the intermediate member may be made from a plurality of separate parts.
  • the parts may be of the same size (within a factor of 2).
  • the parts may be joined together. However, it is preferred that the parts are not joined (and preferably not specially configured for joining), but are instead placable in position relative to each other in use. During use the relative positions of the parts may be substantially maintained by means other than directly joining the parts.
  • the intermediate member is preferably reusable.
  • the intermediate member is preferably able to deform repeatedly to substantially the same shape, that shape being dependent on the shape of the shaped surface.
  • the shaped surface is advantageously defined by an open structure.
  • the open structure may for example be open in that the notional surface that smoothly envelopes the structure in the region of the shaped surface bridges openings, holes, gaps or the like in the shaped surface.
  • the open structure may include elements separated by gaps.
  • the shape to which the component may be modified is dependent on the shape defined by the notional smooth surface enveloping the elements and bridging the gaps.
  • the intermediate member is advantageously sufficiently stiff that in use during the forcing of the aircraft component against the shaped surface, the intermediate member deforms substantially to the shape of said notional smooth surface, but suffers substantially no local deformation in regions of the intermediate member that bridge the gaps.
  • the intermediate layer is advantageously arranged to be free to move over the shaped surface within predefined boundaries. Allowing the intermediate member to be so freely movable means that there is no need for locating elements for fixing the intermediate member in fixed position and therefore simplifies construction and operation of the apparatus.
  • the apparatus may be arranged such that the aircraft component is free to move in directions substantially parallel to the shaped surface.
  • the apparatus is preferably arranged such that, in use, the aircraft component is prevented from moving beyond predefined boundaries.
  • Allowing the aircraft component to be so freely movable means that there is no need for locating elements for fixing the aircraft component in fixed position and therefore simplifies construction and operation of the apparatus. Also, fixing the position of more than one point of the component can create internal stresses within the component when the component is forced to conform to the shape of the shaped surface.
  • the component may of course be fixed at a single point relative to the apparatus.
  • the freedom of movement of the intermediate member and/or the component may be limited in distance, the distance being relatively short compared to the maximum dimension of the component. For example, the distance may be less than 1cm and is preferably of the order of a few millimetres.
  • the predefined boundaries mentioned above may be defined by at least one stop.
  • the at least one stop may be in the form of a raised element.
  • the or each stop may be fixed to a base and extend from the base past the shaped surface.
  • the apparatus advantageously includes a base which provides structural support for the shaped surface.
  • the apparatus preferably includes a base comprising a plurality of base modules.
  • the base modules are preferably fixed in position relative to each other during operation of the apparatus to modify the shape of the aircraft component.
  • the position of a base module relative to another base module is advantageously adjustable.
  • the base modules may be so arranged that the position is adjustable with only one degree of freedom.
  • the apparatus is advantageously so arranged so that an adjacent pair of base modules are pivotally movable relative to each other.
  • Arranging the base modules to be adjustable to one another allows the global shape of the shaped surface to be altered without needing to alter the structure of the shaped surface, or at least without needing to alter significantly the structure of the shaped surface.
  • the shape of the shaped surface be fixed during operation of the apparatus to modify the shape of the aircraft component
  • the apparatus could be arranged such that the shape of the shaped surface changes during said operation.
  • the base modules could be moved during operation of the apparatus to modify the shape of the aircraft component.
  • base modules There may be as few as two or three base modules and there may be as many as ten or more modules. There are preferably a multiplicity of base modules. In the embodiment described below there are four base modules. The apparatus is advantageously so arranged that the base modules are arranged in a single row.
  • the shaped surface advantageously comprises an open structure.
  • the open structure may comprise a multiplicity of spaced apart elements.
  • the shape to which the component may be modified may be dependent on the shape defined by a notional surface that envelopes the elements.
  • the apparatus may advantageously be so configured that if the shape of the shaped surface needs adjusting it may be necessary only to adjust or alter the shapes of a small number of elements in comparison to the total number of the elements.
  • the shaped surface is advantageously defined by a multiplicity of separate elements.
  • the elements are preferably arranged in groups, each group comprising a plurality of elements.
  • the elements in each group are preferably mounted in fixed relation to each other.
  • the elements are preferably spaced apart from each other.
  • the elements may each be in a form having a characteristic of shape that is substantially the same for each element (for example to ease manufacture of the elements).
  • each element may have the same thickness, the same cross-sectional shape, or share some other characteristic of shape.
  • the elements are preferably in the form of ribs.
  • Each rib may for example have the same general thickness.
  • the ribs may be similar in function, and therefore construction, to the ribs in an aircraft wing.
  • the spacing between successive elements may conveniently be the same. However, the apparatus may be arranged such that the spacing between successive elements is different at different regions of the apparatus. It may be necessary for there to be more elements per unit length in certain regions. For example, if the part of each element that defines the shape of the shaped surface has the substantially the same unit area (or the same width in the direction of successive elements, for example in the case where the elements are in the form of ribs), then there may be regions of the shaped surface that have a shape that varies greatly requiring more elements per unit area/length than in regions where the shape does not vary so greatly.
  • the elements are advantageously removably mounted on the apparatus.
  • the shape of the shaped surface may be readily adjusted by removing and replacing one or more elements with one or more elements of a different shape.
  • the elements may be fixed in position on the apparatus by means of a portion of the element that engages with a corresponding portion of the apparatus.
  • the portions and corresponding portions are preferably shaped such that they do not restrict movement of the elements away from the apparatus.
  • the elements may able to be slotted into the apparatus, by suitably aligning the portion of the element with the corresponding portion of the apparatus and then causing one to be inserted into the other.
  • the shape of the shaped surface does not significantly alter from one operation of the apparatus to the next.
  • the shaped surface is preferably rigid.
  • the shaped surface is preferably so configured has that during use of the apparatus the shaped surface undergoes substantially no deformation.
  • the shaped surface preferably has a surface area greater than 1m2, and more preferably greater than 5m2.
  • the invention has particular application when the shaped surface has an area greater than 10m2. In the embodiment described below, the surface area is greater than 25m2.
  • the shaped surface is preferably so arranged and configured for modifying the shape of components, wherein the surface of the component that is forced against the shaped surface is generally smooth in shape both before and after having its shaped modified.
  • the component may, during use of the apparatus, be forced against the shaped surface by any suitable means.
  • a mechanical clamping force could for example be utilised.
  • the apparatus is arranged such that the component is, in use, forced against the shaped surface by means of an air pressure difference.
  • the air pressure difference is at least partially provided by suction.
  • the apparatus may for example include a bagging apparatus, via which the suction may be provided.
  • an apparatus for modifying the shape of an aircraft component including a shaped surface so arranged that an aircraft component may be forced against the shaped surface in a manner that modifies the shape of the aircraft component, wherein the apparatus is arranged such that the component is, in use, forced against the shaped surface by means of an air pressure difference that is at least partially provided by suction via a bagging apparatus.
  • the bagging apparatus for example, comprises a bag and a source of suction.
  • the apparatus is preferably arranged such that the bagging apparatus, in use, must encompass both the aircraft component and at least a portion of the apparatus on the opposite side of the shaped surface to the aircraft component.
  • the apparatus may include a base which supports the shaped surface. In such a case the apparatus is advantageously arranged such that the bagging apparatus, in use, must at least partially be sealingly attached to the base.
  • the bagging apparatus, in use may be sealingly attached to the base by means of an endless seal.
  • the bagging apparatus may, in use, encompass substantially the whole of the part of the apparatus that defines the shape of the shaped surface, that part being positioned between the shaped surface and the base.
  • a bagging apparatus arranged in any of the manners described immediately above enables the structure between the base of the apparatus and the shaped surface of the apparatus to be an open structure and/or a structure in which there are gaps, which in turn enables that part of the apparatus to be constructed to provide advantageous features that might not otherwise be feasible.
  • a bag 105 is attached to the tool 101 very near to or on the upper shaped surface 103 of the tool 101.
  • the shaped surface 103 In order for air to be drawn from the region between the bag 105 and the shaped surface 103, the shaped surface 103 must be completely airtight.
  • the shaped surface 103 is generally formed from a solid sheet of tooling metal that is fixed to the base 102.
  • At least the bag of the bagging apparatus of the present invention is preferably reusable. Having a reusable bagging apparatus may be especially advantageous when the volume that the bag must encompass is of significantly greater volume than the aircraft component
  • the suction is preferably provided by a vacuum pump.
  • the invention is of particular advantage when the apparatus is in the form of a creep-forming tool and/or when the apparatus is arranged so that it is suitable for modifying the shape of metallic components.
  • the invention may of course have application as an apparatus that modifies the shape of a component in a different manner or as an apparatus for forming non-metallic components.
  • the apparatus could be of application in relation to forming components from composite materials, for example, where the component is formed from a multiplicity of fibre layers in a resin matrix.
  • the invention also provides according to a fourth aspect a method of modifying the shape of an aircraft component, the method including the steps of providing a shaped surface, the shape of which being adjustable, forcing an aircraft component against the shaped surface in a manner that modifies the shape of the aircraft component, and removing the aircraft component.
  • the method may further include the steps of observing the modified shape of the aircraft component and comparing the modified shape so observed with an ideal shape. If the modified shape of the aircraft component is identical to the ideal shape, or sufficiently close to the ideal shape for practical purposes, then the shaped surface need not be adjusted. If the modified shape of the aircraft component is not sufficiently close to the ideal shape, then the shaped surface may need to be adjusted. The method may further include the step of adjusting the shape of the shaped surface to compensate for the differences between the observed modified shape of the aircraft component and the ideal shape.
  • the method may include a step of forcing a further aircraft component against the adjusted shaped surface in a manner that modifies the shape of the aircraft component, and then removing the further aircraft component.
  • the method may also include a step of then observing the modified shape of the further aircraft component and comparing the modified shape so observed with the ideal shape.
  • the observed shape may still not be close enough to the target shape and the shaped surface may need to be adjusted more than once in order to enable the shaped surface to produce components of the target shape.
  • the following steps are preferably performed as many times as are necessary until the differences between the observed modified shape of the aircraft component and the ideal shape are within predetermined acceptable tolerances: adjusting the shape of the shaped surface to compensate for the differences between the observed modified shape of the aircraft component and the ideal shape and then forcing a further aircraft component against the adjusted shaped surface in a manner that modifies the shape of the aircraft component, removing the further aircraft component, observing the modified shape of the further aircraft component and comparing the modified shape so observed with the ideal shape.
  • the invention yet further provides according to a fifth aspect a method of modifying the shape of an aircraft component, the method including the steps of providing a shaped surface and an intermediate member, forcing an aircraft component against the shaped surface, via the intermediate member, in a manner that modifies the shape of the aircraft component, and removing the aircraft component.
  • the step of the fourth aspect of the invention of forcing the aircraft component against the shaped surface may be performed such that the aircraft component is forced against the shaped surface, via an intermediate member.
  • the intermediate member advantageously receives and supports the component.
  • the intermediate member is positioned between the shaped surface and the component.
  • the intermediate member advantageously deforms to a shape dependent on the shape of the shaped surface.
  • the intermediate member may be sufficiently stiff that, in use during the forcing of the aircraft component against the shaped surface, the intermediate member deforms substantially to the shape of said notional smooth surface, but suffers substantially no local deformation in regions of the intermediate member that bridge the gaps.
  • the intermediate member may have any of the features described above with reference to the apparatus of the present invention.
  • the intermediate layer may be arranged to be free to move over the shaped surface within predefined boundaries
  • the intermediate member is preferably substantially flat.
  • the method according to any aspect of the invention is advantageously performed a multiplicity of times. When an intermediate member is used, it is preferred that the same intermediate member is used on each occasion.
  • the method is preferably so performed that during the step of forcing of the aircraft component against the shaped surface, the aircraft component undergoes plastic deformation.
  • the component may undergo some form of heat treatment.
  • the component may for example be placed in an oven, autoclave or similar apparatus.
  • the heat treatment is applied after the aircraft component is initially forced against the shaped surface.
  • the initial (cold) deformation of the component may be largely elastic with little or substantially no plastic deformation.
  • the component may undergo some elastic deformation.
  • the method will normally include a step of releasing the component from the shaped surface. After the release of the component, the shape of the component may change significantly.
  • the method is performed on a metal component in such a way that causes the metal to creep (i.e. a creep forming method), the changing of the shape of the component may be described as spring-back.
  • the method may be used to make components of any desired shape.
  • the components may for example be components that may be made from substantially flat sheets of material, such as a portion of a wing skin.
  • the aircraft component Before performance of the step of forcing of the aircraft component against the shaped surface, the aircraft component may be generally flat in shape. It will be appreciated that in the case where the component is a wing skin, one side of the wing skin may be flat, whereas the other side is not completely flat, such that the component has regions of significantly different thickness. It is preferred that if the component has a flat face and a non-flat face, that the flat face is placed against the shaped surface.
  • the aircraft component may slide over the shaped surface within predefined boundaries.
  • the relation sliding, or slipping, of the surfaces may be due primarily to stretching of the component in given regions by virtue of the stresses within the component caused by it being forced to conform to the shape of the shaped surface.
  • the shaped surface is advantageously supported (directly or indirectly) by a plurality of base modules.
  • the method may include a step of adjusting and fixing the position of one base module relative to another.
  • the fixing of the positions of the base modules is readily changeable.
  • the changing of the positions advantageously does not include any step that is destructive in nature.
  • the fixing of the relative positions of the base modules does not include any welding steps.
  • the step of adjusting and fixing the position of one base module relative to another is performed between successive steps of forcing of the aircraft component against the shaped surface.
  • the shaped surface may be defined by a multiplicity of separate elements.
  • the method may include a step of adjusting the shape of the shaped surface by replacing one or more of the separate elements. For example, a component previously produced by the shaped surface may be incorrectly shaped or the shaped surface may need altering in order to produce components of a slightly different shape (because for example the design of the component has been altered, thereby altering the target shape).
  • the step of replacing one or more of the separate elements is performed between successive steps of forcing of the aircraft component against the shaped surface.
  • the step of adjusting the shape of the shaped surface preferably includes replacing a group of a plurality of separate elements.
  • the replacing of an element preferably includes the steps of simply lifting the element from a surface on which it is supported and removing the element, and providing and moving a replacement element until it locates itself into position (for example by slotting into position).
  • the elements may be arranged in the manner described with reference to any of the aspects of the apparatus of the present invention as described herein.
  • the shaped surface preferably undergoes substantially no plastic strain. Preferably, there is no significant elastic strain of the shaped surface.
  • the aircraft component is advantageously forced against the shaped surface by means of an air pressure difference.
  • the air pressure difference may at least partially be provided by suction and is preferably provided via a bagging apparatus including a bag.
  • the air pressure difference is conveniently at least about 1 bar.
  • the air pressure difference may be greater than 1 bar, but of course such pressure differences would not be achievable solely by means of suction.
  • the pressure may be increased by means of using an autoclave or other vessel able to create an environment having a pressure substantially greater than atmospheric pressure.
  • a method of modifying the shape of an aircraft component including the steps of providing a shaped surface, forcing, by means of an air pressure difference, an aircraft component against the shaped surface in a manner that modifies the shape of the aircraft component, and removing the aircraft component, wherein the air pressure difference is at least partially provided by suction via a bag of a bagging apparatus.
  • the shaped surface may be supported by a support structure.
  • the bag preferably encompasses both the aircraft component and at least a portion of the support structure on the opposite side of the shaped surface to the aircraft component.
  • the bag encompasses both the aircraft component and at least a portion of the support structure that supports the shaped surface.
  • the support surface encompassed by the bag is on the opposite side of the shaped surface to the aircraft component.
  • Such a method enables the support structure to be an open structure. A part of the support structure may form (or define) the shaped surface.
  • the shape of a further aircraft component may be modified by performing the method with the use of the same bagging apparatus.
  • the same bag is preferably used. Whilst the same bagging apparatus may be re-used it will be understood that certain sealing materials, such as bag tape, if required may not be reusable.
  • the method may of course be used to modify the shape of a metallic aircraft component.
  • the method may be incorporated in a method of creep forming an aircraft component.
  • the present invention is of particular application to a method of creep forming a metallic component.
  • a creep forming method may include for example the use of an apparatus according to any of the first to third aspects of the present invention or the performance of the steps of the method according to any of the fourth to sixth aspects of the present invention.
  • the apparatus and method of the invention may be used to modify the shape of aircraft components, which, before the use of the apparatus or performance of the method, have already been subjected to various manufacturing processes. Further manufacturing processes may of course be performed after the shape of a component has been modified. It will therefore be understood that the term component is used herein both to refer to the component in a state ready for final assembly and to earlier stages in the component's manufacture.
  • the present invention also provides an aircraft component formed by the use of an apparatus according to any of the first to third aspects of the present invention or the performance of the steps of the method according to any of the fourth to sixth aspects of the present invention.
  • the aircraft component so formed may for example be a wing skin or a portion thereof.
  • the invention is of course of particular advantage when the aircraft component so formed has a shape that is relatively complicated.
  • the shape of the component, once modified, may be irregular and not easily definable mathematically.
  • More than 50 parameters may for example be required to define adequately the shape of the shaped surface or the modification to be made to the shape of the component.
  • More than 200 parameters may for example be required.
  • the aircraft component so formed may for example be part of a complex structure such as a wing, a fuselage or any other part of an aircraft.
  • the embodiments of the present invention described below relate to the forming of a section of the wing skin of an aircraft. It will of course be appreciated that the present invention may be applicable to other component parts of an aircraft. Such components include, in particular, any part that is required to have a complex shape and that may be caused to adopt that complex shape (within acceptable tolerable differences) from an initial different shape by means of forcing the component against an appropriately shaped surface.
  • the invention also has particular application in relation to metallic components that need to be hardened by precipitation hardening. It will be apparent to the skilled person that the invention has particular application to components able to be formed from sheet material such as skin sections, but it should also be appreciated that the invention has application in relation to components, which are generally not flat in shape, even immediately before modifying their shape.
  • the present invention yet further provides an aircraft including an aircraft component as described above.
  • any preferred or optional features of one aspect of the present invention may be incorporated into any other aspect of the invention.
  • any aspect of the method of the invention may be performed with an apparatus of the invention incorporating features of a given aspect of the apparatus of the invention.
  • the apparatus may furthermore be so configured that it is able to perform the method of the invention.
  • Figure 2a shows a creep forming tool according to an embodiment of the present invention
  • Figure 2b shows a section of the tool of Figure
  • Figure 3a is a perspective view of a part of the tool including a group of rib boards
  • Figure 3b is a plan view of the group of rib boards of Figure 3a
  • Figure 4 is a side view showing how the rib boards locate on the base of the tool
  • Figure 5 shows the tool of the embodiment together with a bag placed over the tool
  • Figure 6 shows a perspective view from above of a section of the tool showing the configuration and arrangement of the rib boards.
  • Figures 2a and 2b show a creep forming tool 1 for producing an aircraft component 4 (not shown), in the form of a metal wing skin portion of a complex shape.
  • the component initially has a shape that is generally flat.
  • the bottom face of the component 4 is substantially planar, whereas the top face, whilst generally flat, has a complicated structure, which enables the wing skin both to provide a smooth aerofoil surface (the lower face) and to have certain mechanical properties (provided by the varying thickness of the skin, which is defined by the structure of the upper face).
  • the tool 1 comprises a base 2 on which there are supported a plurality of rib boards 6.
  • the base 2 includes a movable support structure (not shown in Figures 2a and 2b) in the form of a bogie unit (or support trolley).
  • the uppermost surfaces 6a of the rib boards 6 define a shaped surface, against which the component 4 is forced, via an intermediate plate 12 (also not shown in Figures. 2a, 2b), for a predetermined length of time in a manner that is described in further detail below.
  • the lower flat surface of the component 4 is thus forced to adopt a shape substantially the same shape as the notional surface (represented by the dotted line 3 in Figure 2a) that smoothly envelopes the upper surfaces 6a of the rib boards 6. After the component 4 is released, it springs back into a shape determined by the shape of the shaped surface defined by the rib boards 6.
  • each wing skin portion is about 33m in length and has a maximum width of 2.7m.
  • the thickness of the wing skin varies from about 2mm up to about 32mm.
  • the apparatus is therefore elongate in nature and has a long length and a short width.
  • the intermediate plate 12 is in the form of a stainless steel 8mm thick plate, which when the component 4 is forced against the rib boards 6, supports the component and is positioned between the component 4 and the rib boards 6.
  • the intermediate plate is, when not subjected to any load, substantially flat and is very slightly larger in plan view than the component 4 which it supports.
  • the base 2 comprises four base modules 2a (only three of which are shown in Figure 2a for the sake of clarity).
  • the base modules 2 are arranged in series and adjacent modules 2 are pivotally connected.
  • the position of one module 2 relative to the adjacent module is temporarily fixed by means of an angle piece 7 (illustrated schematically in Figure 2a).
  • the angle piece 7, in the form of a wide angle plate, is bolted via a sealing gasket to the two base modules.
  • Each base module 2a includes its own independently movable support structure (i.e. the bogie mentioned above) on which the main body of the base is supported.
  • Many rib boards 6 are provided in series on each base module (only three being shown in Figure 2a for the sake of clarity).
  • the rib boards 6 are grouped in banks of four rib boards 6, the rib boards 6 in each bank being fixed and spaced apart by means of spacing rods 7 that run between the rib boards and are fixed in place by bolts 8.
  • Each rib board has six positions at which spacing rods are attached to it, there being one at each corner, one in the middle towards the top of the rib board 6 and one in the middle towards the bottom of the rib board 6.
  • Fig 3a only one set of spacing rods 7 and bolts 8 is illustrated for the sake of clarity, although the positions of the other rods are indicated by crosses X.
  • Figure 6 shows in perspective a view from above of a section of the tool showing the configuration and arrangement of the rib boards 6.
  • the rib boards 6 are removably located on the uppermost surface 2b of the base 2, by means of a combination of at least four (only two being shown in Figs. 2b and 4 for the sake of clarity) lengthwise lines of spacing blocks 9 on the base 2 and at least one rod 10 that extends along the central length of the base 2.
  • Two lines of spacing blocks are provided on one side of the rod, and two on the other, the lines of blocks and the rod all being roughly evenly spaced apart across the width of the base.
  • more than one rod 10 and/or more than four spacing blocks 9 are provided to provide adequate coverage across the width of the base.
  • eight lines of spacing blocks 9 are provided across the width of the base 2.
  • the spacing blocks 9 are so positioned that the lower portion 6b of each rib board 6 is positioned against the side of a block 9.
  • the spacing of the blocks 9 is such that two rib boards 6 are positioned between a pair of adjacent blocks 9.
  • each rib board 6 contacts a single block 9.
  • the ribs are equally spaced apart and as such the distance between spacing blocks 9 is equal to the length I of a spacing block plus the thickness of two rib boards 6.
  • the positioning of the blocks 9 on the base therefore determine the longitudinal position of the banks of the rib boards 6. Since, each rib contacts a spacing block, the number of ribs in a single bank can if desired be reduced or increased.
  • Each rib board 6 has a recess 11 in the middle of its bottom surface 6b, the recess 11 being so shaped that the rod 10 snugly fits in and is accommodated by the recess 11.
  • the positioning of the rod 10 and the recesses 11 in the rib boards 6 determine the widthwise position of the rib boards 6.
  • the banks of rib boards 6 are therefore easily removable from the base 2 and are also easily positioned in the base 2 by slotting the bank of rib boards 6 in position relative to the rod 10 and the spacer blocks 9.
  • the rib boards 6 are each in the form of generally flat sheets of tooling steel having a thickness of 12mm. The rib boards are positioned apart by
  • the rib boards may be provided with thickened portions in order to provide extra strength.
  • the rib boards are substantially rigid and undergo negligible deformation under normal operating conditions.
  • the rib boards 6, once positioned on the base 2, are surrounded on all sides as viewed from above by removable side plates (not illustrated).
  • the side plates are bolted to, and are supported by, the base 2.
  • Also attached to the base are stops (not illustrated) that extend from the periphery of the upper surface of the base 2, but within the perimeter defined by the removable side plates.
  • the stops define a boundary within which the intermediate member is positioned.
  • the boundary defined by the stops closely matches the shape of the intermediate plate 12 as viewed from above, which itself has a shape, which, although slightly larger in plan view, closely matches the shape of the component 4.
  • the stops allow the intermediate plate 12 and the component 4 to be positioned on the surface in the correct position, within an acceptable tolerance distance, and yet also allow both the intermediate member and the component to slide freely by relatively small distances over the surface defined by the ribs.
  • the intermediate member may thus be considered as being in floating contact with the ribs and the component may be considered as being in floating contact with the intermediate member.
  • portions or points of the intermediate member and/or the component do not move any substantial distance relative to the base.
  • the apparatus also includes a reusable silicone vacuum bag 5 (not shown in Figs 2 to 4) and a source of suction, which is provided by means of a vacuum pump.
  • the vacuum bag 5 is shaped such that the component 4, intermediate plate 12 and rib boards 6 are encompassed by the bag 5, the open end of which being attachable to the upper surface 2b of the base 2 by means of bag tape.
  • the bag 5 is attached to the base 2 in the region next to the side plates (mentioned above) which are provided on the base and which surround the rib boards 6 as viewed in plan. The side plates prevent or mitigate suck-in of the bag 5 when a vacuum is drawn.
  • the process of creep forming of a component 4 will now be described with reference to Figure 5.
  • the component 4 is machined or manufactured such that the component 4 has a substantially flat side 4a, the side that will eventually form the outermost surface of the wing skin and a side 4b that has a shape that is not flat and that will form the surface of the wing skin inside the wing box of an aircraft.
  • the component 4 is machined from a solid block of 7150 alloy.
  • the intermediate plate 12 is placed on the base 2 and the component 4 is then placed on the tool 1 so that the flat surface 4a of the component 4 is placed against the uppermost surface 12a of the intermediate member 12.
  • a breather mat (indicated by line 13) is placed on top of the component 4 and then the vacuum bag 5 is placed over the component 4, intermediate plate 12 and the rib boards 6.
  • the bag 5 is sealingly attached to the upper surface 2b of the base 2 by means of bagging tape attached to the base (see the end portion 5a of the bag 5 which indicates broadly where the bag tape is fixed).
  • the vacuum bag 5 is connected to a source of suction, which then creates a vacuum within the bag 5.
  • the intermediate plate 12 and component 4 are urged towards the uppermost surfaces 6a of the ribs 6.
  • the intermediate plate 12 and component 4 adopt the shape defined by the ribs 6 and are positioned within the area defined by the ridge.
  • Figure 5 shows schematically how the various parts are positioned at this stage in the process.
  • the apparatus 1 and component 4 are then subjected to suitable temperature and pressure profiles over time in order to creep-form the component 4.
  • the autoclave is operated to provide a pressure difference of 7 bar (i.e. 6 bar above atmospheric pressure) and at an initial temperature of 120°C ⁇ 5°C for five hours and then at a temperature of 155°C ⁇ 5°C for 10 hours.
  • the intermediate plate 12 undergoes substantially no plastic deformation when forced against the ribs 6.
  • the intermediate plate 12 presses against the upper surfaces 6a of the ribs 6 so that good contact is made between the plate 12 and the entire uppermost surface 6a of each rib 6 immediately opposite the plate 12.
  • the previously flat surface 4a of the component 4 is pressed against the opposing surface 12a of the intermediate member 12 so that there is good contact across substantially the entire surface area of that surface 4a of the component 4.
  • the intermediate plate 12 is rigid enough that substantially no sagging of the plate 12 occurs in the gaps between the rib boards 6, yet is flexible enough that it deforms to the shape 3 that smoothly envelopes the uppermost surfaces 6a of the rib boards 6.
  • the base modules 2a receive, resist and distribute the load sustained by the rib boards 6 from the forcing of the component 4 against the rib boards 6 via the intermediate plate 12.
  • the apparatus is removed from the autoclave and air is allowed to be slowly drawn back into the bag, thereby allowing the component 4 and intermediate member 12 to be released from the tool.
  • the component 4 will undergo spring back, in that the shape of the component 4 will spring back partly towards its original flat shape.
  • the intermediate plate 12 will spring back to a substantially flat plate.
  • one or more banks of rib boards may need replacing and/or the relative position of the base modules may need changing in order to remove or reduce the error in shape of the component produced compared to the ideal or target shape.
  • Standard prior art methods are available to determine how the shape of the shaped surface should be changed in view of a given error. Such methods can be iterative in nature and several revisions of the shape of the shaped surface may be required.
  • Remedying errors in shape may be best performed by the replacement of one or more banks of rib boards, the repositioning one or more base modules, or a combination of the two. Local errors may for example, merely require the replacement of one or more banks of rib boards. Large errors in shape may be best dealt with by both replacing several banks of rib boards and repositioning several base modules. Errors that affect only the longitudinal (or spanwise) shape may be remedied by means of only repositioning the base modules relative to each other.
  • the angle piece between the two base modules concerned In order to move the position of one base module to another it will at least be necessary for the angle piece between the two base modules concerned to be removed, for the relative positions of the base modules to be modified, for support structure (i.e. the bogie unit) of the base module to be modified as necessary, and for an angle piece corresponding to the new angle between the base modules to be fixed to the base modules.
  • the side plates and rib boards mounted on the base modules need not be moved in order to reposition the base modules. Banks of rib boards may simply be replaced by lifting a bank out and replacing with a bank of boards that is slotted into place. One or more side plates may need to be removed to facilitate access, but this need not necessarily be the case if suitable lifting gear is available to lift reliably and safely the banks out of the base and up and over the side plates.
  • the intermediate member could be dispensed with.
  • each rib Whilst each rib provides a surface of contact across its entire length (i.e. widthwise across the base) for the intermediate plate, the ribs could instead be provided in two or more rows of ribs, each row running spanwise along the length of the base, there being a gap between adjacent rows.
  • the tool could be provided with a single ridge that defines the boundary within which the intermediate plate and the component are able to move.
  • the ribs need not be evenly spaced apart.
  • the intermediate plate need not be of uniform thickness.
  • the apparatus and component may be subjected to different pressure and temperature profiles in the autoclave. Pressure differences may range from between 2 and 15 bar, more preferably between 5 and 10 bar. Temperatures may range from 100 C to 200 C. The total time in the autoclave may be between 6 and 20 hours.

Abstract

L'invention concerne un outil de formation de fluage conçu pour modifier la forme d'un élément aéronef (4) afin d'obtenir une portion de revêtement de voilure. L'outil (1) décrit dans cette invention comprend une surface formée (3) définie par des plateaux à nervures amovibles (6). L'élément (4) est poussé contre la surface formée (3), par l'intermédiaire d'une plaque intermédiaire réutilisable (12). La forme de la surface formée (3) peut être ajustée, si nécessaire, par remplacement des plateaux à nervures par des plateaux (6) présentant une forme différente.
PCT/GB2003/005455 2002-12-18 2003-12-15 Procede et outil de fabrication d'element d'aeronef WO2004054734A1 (fr)

Priority Applications (4)

Application Number Priority Date Filing Date Title
US10/539,017 US20060042347A1 (en) 2002-12-18 2003-12-15 Aircraft component manufacturing tool and method
CA002510154A CA2510154A1 (fr) 2002-12-18 2003-12-15 Procede et outil de fabrication d'element d'aeronef
AU2003288468A AU2003288468A1 (en) 2002-12-18 2003-12-15 Aircraft component manufacturing tool and method
EP03780389A EP1581356A1 (fr) 2002-12-18 2003-12-15 Procede et outil de fabrication d'element d'aeronef

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB0229434.6 2002-12-18
GBGB0229434.6A GB0229434D0 (en) 2002-12-18 2002-12-18 Aircraft component manufacturing tool and method

Publications (1)

Publication Number Publication Date
WO2004054734A1 true WO2004054734A1 (fr) 2004-07-01

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PCT/GB2003/005455 WO2004054734A1 (fr) 2002-12-18 2003-12-15 Procede et outil de fabrication d'element d'aeronef

Country Status (6)

Country Link
US (1) US20060042347A1 (fr)
EP (1) EP1581356A1 (fr)
AU (1) AU2003288468A1 (fr)
CA (1) CA2510154A1 (fr)
GB (1) GB0229434D0 (fr)
WO (1) WO2004054734A1 (fr)

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WO2007022143A1 (fr) * 2005-08-18 2007-02-22 Floodcooling Technologies, L.L.C. Ensemble et procede pour refroidir et/ou former un element
CN102284589A (zh) * 2011-07-26 2011-12-21 中南大学 一种金属蠕变成形模具
WO2013188663A1 (fr) * 2012-06-13 2013-12-19 Norgren Automation Soulutions, Llc Appareil pour soutenir une pièce
CN104759542A (zh) * 2015-04-14 2015-07-08 西北工业大学 一种恒温箱零件时效成形装置
US11185955B2 (en) 2016-02-15 2021-11-30 Norgren Automation Solutions, Llc Template support for workpiece

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BE1018819A3 (nl) * 2009-07-08 2011-09-06 Noyez Francky Inrichting voor het vormen van vormstukken die vervaardigd zijn uit kunststof en bouwelement voorzien voor een dergelijke inrichting.
CN104971993B (zh) * 2014-04-10 2017-02-15 哈尔滨建成集团有限公司 一种导柱移出式上下模组合变换一模三用起伏模具
CN104384323B (zh) * 2014-10-08 2016-10-05 西北工业大学 一种恒温箱零件时效成形装置
CN108127031A (zh) * 2017-12-26 2018-06-08 广州敏惠汽车零部件有限公司 一种成型和矫形一体化的模具结构
CN110252881B (zh) * 2019-06-28 2020-09-01 中南大学 一种蠕变时效成形调控方法

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EP0448339A1 (fr) * 1990-03-22 1991-09-25 United Technologies Corporation Procédé pour former des aubes creuses
EP0507033A1 (fr) * 1991-04-05 1992-10-07 Manuel Torres Martinez Installation de machine outil pour fixer et usiner
EP0570212A1 (fr) * 1992-05-14 1993-11-18 Kvaerner Masa-Yards Oy Procédé pour la fabrication d'un grand réservoir cintré
US6264771B1 (en) * 1995-02-03 2001-07-24 Daimler-Benz Aerospace Ag Process for forming a plate-like component
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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2007022143A1 (fr) * 2005-08-18 2007-02-22 Floodcooling Technologies, L.L.C. Ensemble et procede pour refroidir et/ou former un element
CN102284589A (zh) * 2011-07-26 2011-12-21 中南大学 一种金属蠕变成形模具
WO2013188663A1 (fr) * 2012-06-13 2013-12-19 Norgren Automation Soulutions, Llc Appareil pour soutenir une pièce
CN104768703A (zh) * 2012-06-13 2015-07-08 诺冠自动化解决方案有限责任公司 用于支撑工件的设备
US9651192B2 (en) 2012-06-13 2017-05-16 Norgren Automation Solutions, Llc Apparatus for supporting a workpiece
CN104759542A (zh) * 2015-04-14 2015-07-08 西北工业大学 一种恒温箱零件时效成形装置
US11185955B2 (en) 2016-02-15 2021-11-30 Norgren Automation Solutions, Llc Template support for workpiece

Also Published As

Publication number Publication date
EP1581356A1 (fr) 2005-10-05
GB0229434D0 (en) 2003-01-22
AU2003288468A1 (en) 2004-07-09
CA2510154A1 (fr) 2004-07-01
US20060042347A1 (en) 2006-03-02

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