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Title:
SINUSOIDAL FLANGE
Document Type and Number:
WIPO Patent Application WO/2012/046020
Kind Code:
A1
Abstract:
An apparatus and method for forming a composite component comprising a flange. The flange may be employed to couple the composite component to another component such as a structural part of an engine or the like.

Inventors:
WILES GARY (GB)
Application Number:
PCT/GB2011/051788
Publication Date:
April 12, 2012
Filing Date:
September 22, 2011
Export Citation:
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Assignee:
GKN AEROSPACE SERVICES LTD (GB)
WILES GARY (GB)
International Classes:
B29C70/20; B29C53/82; B29C70/32; B29C70/38
Foreign References:
US20080118683A12008-05-22
GB2452298A2009-03-04
GB2467417A2010-08-04
US20050042410A12005-02-24
Other References:
None
Attorney, Agent or Firm:
ALBUTT, Anthony (120 Holborn, London EC1N 2DY, GB)
Download PDF:
Claims:
Claims

1. A mandrel for forming a composite component, said component comprising a hollow body and a flange on one or both ends thereof; the mandrel comprising:

a first region for forming the hollow body of said component and having a circumferential surface corresponding to the desired inner circumferential surface of the hollow body; and

a second region on one or each end of said mandrel for forming the or each flange of said component,

wherein the second region comprises a non-uniform and undulating surface.

2. A mandrel as claimed in claim 1 , wherein the second region is in the form of a three dimensional sinusoidal surface extending from the first region.

3. A mandrel as claimed in any preceding claim, wherein the surface of the second region undulates in a sinusoidal profile and where the amplitude of the sine wave increases from a zero amplitude at the junction of the first and second regions to a final amplitude at a distal boundary of the second region.

4. A mandrel as claimed in claims 2 or 3, wherein the amplitude of the sine wave at a given position measured along the axis of the mandrel is selected such that the circumference of the second region of said mandrel at said position is substantially equal to the circumference of the resulting flange at a corresponding position when the flange is formed.

5. A mandrel as claimed in any preceding claim wherein the mandrel comprises a second region on each end thereof.

6. A mandrel as claimed in any preceding claim wherein the hollow body is a generally barrel shaped portion and the flange is a generally radially extending flange surrounding the end(s) of the barrel.

7. A mandrel as claimed in any preceding claim, wherein the mandrel further comprises heating means arranged in use to heat a composite material attached thereto.

8. A mandrel as claimed in any preceding claim wherein the mandrel can be disassembled into a plurality of parts so as to be removable from the composite component formed thereon.

9. A mandrel as claimed in any preceding claim wherein the composite material is layed-up onto the inner surface of the mandrel.

10. A tool for forming a composite component, said component comprising a flange portion and a hollow body portion; the tool comprising:

a first circumferentially extending region for forming a flange surface; and a second region disposed within the first circumferentially extending region for forming the hollow body portion;

wherein the second region comprises a non-uniform and undulating surface.

11. A tool as claimed in claim 10, wherein the second region is in the form of a three dimensional sinusoidal surface extending radially inwards from said first circumferentially extending region. 12. A tool as claimed in claim 10 or 11 , wherein the surface of the second region undulates in a sinusoidal profile and where the amplitude of the sine wave increases from a zero amplitude at the junction of the first and second regions to a final amplitude at a distal inner boundary of the second region. 13. A tool as claimed in claims 10 to 12, wherein the amplitude of the sine wave at a given radial position of the tool is selected such that the circumference of the surface of the second region at said position is substantially equal to the

circumference of the resulting hollow body.

14. A tool as claimed in any of claims 10 to 13 wherein the hollow body is a generally tubular or barrel shaped portion and the flange is a generally radially extending flange surrounding the end(s) of the barrel.

15. A tool as claimed in any of claims 10 to 14, wherein the tool further comprises heating means arranged in use to heat a composite material attached thereto.

16. A tool as claimed in any of claims 10 to 15, wherein the tool can be disassembled into a plurality of parts so as to be removable from the composite component formed thereon.

17. A method of manufacturing a composite component using a tool according to any of claims 10 to 16, said method comprising the steps of:

laying-up a composite material onto said first and second regions to form a composite stack;

removing a portion of said tool corresponding to the second region to release a portion of the the layed-up composite stack;

forming the flange by moving the portion of the composite stack layed-up onto the second region into a predetermined orientation with respect to the first region.

18. A method according to claim 17, wherein the flange is formed by rotating the portion of the composite material layed-up on the second region so as to be perpendicular to the portion of the composite stack layed-up on the first region.

19. A method according to claim 17 or 18 further comprising the step of adjoining the second region of said component to a hollow body.

20. A method according to any of claims 17 to 29 wherein composite material is layed-up onto said first and second regions in the form of a plurality of uni-directional composite plies.

21 A method according to claim 20, wherein the plies are applied in a circular path around the first and second region.

22. A method of manufacturing a composite component using a mandrel according to any of claims 1 to 9, said method comprising the steps of:

laying-up a composite material onto said first and second regions to form a composite stack; removing a portion of said tool corresponding to the second region to release a portion of the the layed-up composite stack;

forming the flange by moving the portion of the composite stack layed-up onto the second region into a predetermined orientation with respect to the first region.

23. A method according to claim 22, wherein the flange is formed by rotating the portion of the composite material layed-up on the second region so as to be perpendicular to the portion of the composite stack layed-up on the first region. 24. A method according to claim 22 or 23 wherein composite material is layed-up onto said first and second regions in the form of a plurality of uni-directional composite plies.

25 A method according to any of claims 22 to 24, wherein the plies are applied in a circular path around the first and second region.

26. A method according to any of claims 22 to 25, further comprising the step of adjoining the portion of the composite stack formed onto to said first region to a hollow body.

27. A method as claims in any of claims 17 to 26 further comprising the step of curing the component to consolidate the part.

28. A component as claimed in any of claims 1 to 16 wherein the component is a or part of a gas turbine fan case.

29. An gas turbine engine comprising a fan case according to claim 28.

30. An tool or mandrel as substantially described herein with reference to the accompanying figures 1 to 3 and 4B to 10.

31. A method of operating an automated fibre placement machine, said machine programmed to operate according to the method of any of claims 17 to 27.

32. A method as substantially described herein with reference accompanying figures 1 to 3 and 4B to 10.

Description:
Sinusoidal Flange

Field of the Invention

The present invention relates to a method of forming a hollow composite component comprising flange on one or both ends thereof. Particularly, but not exclusively, the invention relates to an improved apparatus and method for forming a fan containment case for a gas turbine engine or the like comprising a flange.

Background

Composite materials have been employed in the aerospace industry for a number of years. The term composite material (also known more generally as 'composites') is used to describe materials comprising fibres such as carbon, glass or the like and an epoxy resin (or similar). Composite materials offer significant advantages for aerospace applications such as lower weight, improved fatigue/damage resistance, corrosion resistance and negligible thermal expansion.

The use of these materials has increased throughout the aerospace industry predominantly because of the fuel savings which can be achieved over the life of an aircraft by reducing the overall sum weight of the components making up the aircraft. Aerodynamic as well as structural components are formed of composite materials such as carbon fibre materials.

One new application for composite materials, such as carbon fibre, is in the manufacture of gas turbine components i.e. aircraft engine components. More specifically the fan containment case of a gas turbine engine can be conveniently manufactured using carbon fibre or other composite materials. It is light, very strong and suitable for components such as the fan case which are not subject to the high temperatures some parts of the engine experience. The fan containment case is essentially a hollow tubular or barrel structure which is conventionally provided with flanges which are used to connect the barrel structure to the surrounding structural elements of the engine. The barrel itself can be conveniently formed using a conventional mandrel arrangement. However, due to the complexity of the barrel and flange combination it has not previously been possible to form a flange from composite material in a convenient manner allowing for large scale production runs. Thus, composite engine components of this type are not regularly employed by engine manufacturers.

The present invention provides an improved method and apparatus for forming a flange from a composite material.

Invention Summar

According to an aspect of the invention there is provided a mandrel for forming a composite component, said component comprising a hollow body and a flange on one or both ends thereof; the mandrel comprising: a first region for forming the hollow body of said component and having a circumferential surface corresponding to the desired inner circumferential surface of the hollow body; and a second region on one or each end of said mandrel for forming the or each flange of said component, wherein the second region comprises a non-uniform and undulating surface.

Thus, according to a first aspect the present invention allows a flange to be form using a multi-region mandrel. The first part of the mandrel is adapted to receive material to lay-up a hollow body and the second part to receive material to form the flange.

It will be recognised that the term flange is used to describe a protruding rim or edge extending generally radially from a generally cylindrical body. The body is not limited to a cylinder and may be any suitable hollow shape. By providing a mandrel with a region comprising a non-uniform and undulating surface it is possible to increase the overall surface area of that region than would have been the case had it simply been planar or uniform in form. The undulations, i.e. peaks and troughs, increase the area onto which composite material can be applied and this advantageously allows a flange to be created.

Creating a flange using composite materials, and in particular carbon fibre materials, is problematic for a number of reasons. For example, the composite materials are normally applied from a narrow tape or ply either manually or by means of an automated advanced fibre placement (AFP) machine. Forming a part with a complex geometry using tape is difficult if not impossible without multiple layers resulting in bulking and excess material usage. The problem is compounded by the mechanical properties of carbon fibre which is strong in tension meaning is it not possible to stretch the material around or over complex tooling. It has been established by the inventor that forming a circular flange or a component comprising a radially extending flange is particularly problematic with composite materials. However, the inventor has established that by adapting a mandrel to comprise an undulating and non-uniform region it is possible to conveniently form a flange using a composite material.

According to the invention the mandrel is adapted in such a way that composite plies layed-up on its surface have the necessary length to conform to the desired flange shape when the flange is formed. Thus, the composite plies are not put under a tensile load when the flange is formed.

The profile of the non-uniform region of the mandrel is adapted according to the particular flange geometry i.e. its radius. Advantageously a three dimensional sinusoidal surface allows the material to be compressed into the region of the tooling whilst still allowing an AFP machine to apply tape to its surface. Put another way, by providing an undulating surface a greater area within a bounded area can be created and onto which composite material can be applied.

Advantageously the surface of this second region of the tool or mandrel is adapted to undulate in a sinusoidal profile with an amplitude which increases from a zero amplitude at the junction of the first and second regions to a final amplitude at a distal boundary of the second region. Thus, at the boundary between the first and second regions there is no deviation from the normal surface profile.

As the composite material is progressively layed-up over the mandrel and away from this junction the material is in effect defining a portion of the flange more and more remote from the hollow body from which the resultant flange extends. The resultant flange will exhibit an increasing circumference as the radius increases. It follows that more and more material is needed on the mandrel to define this circumference the larger the flange gets. This is conveniently accommodated according to the present invention by adapting the profile of the second region so that the amplitude of the sine wave increases corresponding to the increase in the circumference of the flange at each radial position (and therefore the area).

Thus, when the flange is formed there is exactly enough material to define the resulting flange surface and the composite fibres are prevented from being subject to a tensile load during formation of the flange.

The mandrel according to the present invention may comprise a single non-uniform and undulating region so as to create a single flange. Alternatively the mandrel may comprise a pair of these regions, each disposed on an opposing end of the mandrel. Thus a hollow body comprising a pair of flanges can be layed-up. Furthermore, the body itself can be simultaneously layed-up thereby optimising production.

The hollow body may for example be a fan containment case for a gas turbine engine and the flanges arrange to extend radially from one or both ends thereof. The mandrel may advantageously be provided with heating means such that once the composite material has been layed-up and the composite material defining the flange portion moved into position (i.e. perpendicular to the hollow body), the entire composite stack can be cured. The mandrel may alternatively or additionally be arranged to be collapsible so that it can be disassembled to release the composite component.

Advantageously a plurality of composite plies may be applied to the mandrel to create a composite stack.

Viewed from another aspect there is provided a tool for forming a composite component, said component comprising a flange portion and a hollow body portion; the tool comprising: a first circumferentially extending region for forming a flange surface; and a second region disposed within the first circumferentially extending region for forming the hollow body portion; wherein the second region comprises a non-uniform and undulating surface.

As with the first aspect the second region is advantageously provided with an undulating surface. However, in this embodiment the flange portion itself is not the part of the composite stack that is moved but instead the flange is layed-up in a single plane. The second portion of the tooling defines a portion of the composite material that can be moved and which can then be coupled to a body portion such as a cylindrical member.

According to each aspect a flange is formed using a tool or mandrel comprising a nonuniform and undulated surface.

According to the second aspect of the invention the second region is in the form of a three dimensional sinusoidal surface extending radially inwards from said first circumferentially extending region (that is an annular ring). Thus, the composite material forming the flange itself may be layed-up on the first circumferentially extending region and the composite material forming the body portion of the component perpendicular to the flange portion layed-up on the second portion.

According to this second aspect because the flange portion itself has been layed-up the undulating portions does not need to be adapted to account for the increasing radius of the flange once it has been formed. However, the second region according to this aspect does need to provide sufficient material to define the surface of the hollow body once this has been formed.

Thus, advantageously the surface of the second region undulates in a sinusoidal profile and has an amplitude increasing from a zero amplitude at the junction of the first and second regions to a final amplitude at a distal inner boundary of the second region. More specifically, the amplitude of the sine wave at a given radial position of the tool is selected such that the circumference of the surface of the second region at said position is substantially equal to the circumference of the resulting hollow body. Thus according to the invention the second region is adapted is a similar way to the first aspect to provide sufficient material to define the hollow body without exerting a tensile load on the composite fibres. Viewed from another aspect there is provided a method of manufacturing a composite component using a tool as described above, said method comprising the steps of: laying-up a composite material onto said first and second regions to form a composite stack; removing a portion of said tool corresponding to the second region to release a portion of the the layed-up composite stack; forming the flange by moving the portion of the composite stack layed-up onto the second region into a predetermined orientation with respect to the first region.

Viewed from yet another aspect there is provided a method of manufacturing a composite component using a mandrel as described above said method comprising the steps of: laying-up a composite material onto said first and second regions to form a composite stack; removing a portion of said tool corresponding to the second region to release a portion of the the layed-up composite stack; forming the flange by moving the portion of the composite stack layed-up onto the second region into a predetermined orientation with respect to the first region.

Aspects of the invention extend a gas turbine fan containment case and an engine comprising said fan case.

Further aspects extend to a method of operating an automated fibre placement machine programmed to perform one of said methods.

Brief Description of the Drawings

Embodiments of the invention will now be described by way of example only with reference to the accompanying drawings in which:

Figure 1 shows a fan case comprising a pair of flanges;

Figure 2 shows a fan case within a gas turbine engine;

Figure 3 shows a cross-section through a fan case;

Figure 4A shows an alternative method of forming a flange;

Figure 4B shows a barrel flange forming arrangement before the flange has been formed;

Figure 4C shows a barrel flange forming arrangement after the flange has been formed;

Figure 4D shows a radially extending flange arrangement before the flange has been formed;

Figure 4E shows a radially extending flange arrangement after a flange has been formed;

Figure 5A shows a barrel flange forming tool;

Figure 5B shows a formed barrel flange;

Figure 6 shows a cross-section through the mandrel of figure 5 A;

Figure 7 shows a plan view of the mandrel of figure 5 A;

Figure 8 shows layed-up barrel flange;

Figure 9 shows an end view of the flange of figure 4E;

Figure 10 shows an integrated fan case barrel and radially extending flange mandrel.

While the invention is susceptible to various modifications and alternative forms, specific embodiments are shown by way of example in the drawings and are herein described in detail. It should be understood however that drawings and detailed description attached hereto are not intended to limit the invention to the particular form disclosed but rather the invention is to cover all modifications, equivalents and alternatives falling within the scope of the claimed invention. Detailed Description

Figure 1 illustrates a component which can be manufactured according to the present invention. As shown in figure 1 a fan case 1 comprises a hollow body portion 2 and a pair of flanges 3 disposed on either end thereof.

The body portion 2 may be generally tubular or barrel shaped depending on the particular application. As shown in figure 1 the flanges are generally radially extending portions and may subsequently be provided with holes 4 allowing the case to be coupled/decoupled to and from an engine structural component.

Figure 2 illustrates the position of such a fan containment case within a gas turbine engine. The engine 5 comprises a central shaft 6 onto which blades 7 are mounted. The fan case 1 is located around the blades such that should a failure of a blade or part thereof occur the fan case can prevent the blade leaving the engine housing and possibly penetrating the fuselage or fuel tank.

Figure 3 shows a cross-section of a portion of the fan case in-situ. As shown in figure 3 it is necessary to couple the fan case 1 to the structural components 8 of the engine. This is achieved by forming flanges 3, 4 to the ends of the barrel 1. The flanges can then be bonded to adjacent components or coupled to the adjacent components with bolts or the like. The composite material used to manufacture the fan case is generally in the form of a cloth fibre such as carbon fibre pre-impregnated with a resin or a unidirectional fibre tape preimpregnated with a resin. Curing the resin and carbon fibres consolidates the resin and creates a hardened component. To facilitate large scale manufacture of aerospace and other components the composite material is applied to the tooling (a mandrel in this case) by means of an advanced fibre placement (AFP) machine. An AFP machine applies the composite material in the form of a tape from a spool or reel. Such machines are computer controlled and configured to move relative to a tool or mandrel in a plurality of axes allowing composite material to be applied accurately and quickly. An AFP machine is known to the person skilled in the art and will not therefore be described in detail.

Figure 4A shows one alternative manner in which the tapes can be applied to create one type of flange. A shown a mandrel 9 may be provided onto which a plurality of composite tapes 10a, 10b, 10c, lOd and lOe are applied. In the example shown in figure 4A, the tapes have been applied along the inner surface of the mandrel 9.

As shown the tapes have a fixed width and are layed along the length of the inside of the mandrel and then at 90 degrees and radially outwards to create the flange. The movement of the AFP machine is illustrated by the arrow 12.

However, because the tapes have a fixed width, as they are layed onto the radially extending flange a space 11 is created between adjacent plies or tapes. In order to create a uniform flange further plies are layed-up to cover the entire flange portion. However, although this creates the uniform flange surface it does result in an undesirable increase in flange thickness and bulking around the flange.

The present invention provides an apparatus and method for forming two types of flange. The first will be termed a 'barrel flange' and the second an 'upstanding' or 'radially extending' flange. Figures 4B to 4E illustrate these arrangements.

According to the invention a portion of th e tooling or mandrel arranged to form either type of flange is provided with an undulating or more specifically a sinusoidal profile. The profile of the sine wave of the tooling is adapted according to the fl ange which is to be generated. This is described in more detail below.

The flange itself is generally an L shape and arranged at an angle to a hollow body portion. This is normally 90 degrees and allows the component to be coupled conveniently to an adjacent component having a mating surface for the flange. It will be appreciated that the present invention is not restricted to flanges arranged only at 90 degrees. The present invention can be used for manufacture flanges at any angle. As described above the first flange will be termed a barrel flange and an example is shown in figure 4B and 4C. Here the flange is formed by laying-up material onto a tool having two distinct regions Rl and R2 as shown in figure 4B. As shown with reference to Figure 4C the flange is formed by rotating region R2 inwards about the fulcrum line F to create the 90 degree flange. The region Rl can then be coupled to the tubular body portion of the fan case (as shown in figure 1) so as to create a fan case with a flange (this may be by any suitable connection means or by co-curing). As shown in Figure 4B the region R2 comprises an undulating surface which is described in more detail below.

The second flange arrangement is shown in figures 4D and 4E. Here a flange portion is formed by rotating portion Rl outwards about the fulcrum F to create a radially extending flange. The region R2 may be the body portion of the fan case. In this case the flange may be integrally formed with the fan case barrel. Alternatively the region R2 may be a relatively short portion which can be coupled to a fan case barrel. Figure 4E shows the resulting flange and body portion of the fan case. As also shown in Figure 4D the region Rl comprises an undulating surface which is also described in more detail below.

According to the present invention there is provided a method and apparatus for forming both types of flange. In each embodiment a portion of the tooling or mandrel is provided with an undulating sinusoidal profile (see Figures 4B and 4D) which provides the necessary composite material to form the flange.

The respective undulating surfaces will now be described for each flange. Barrel Flange

The barrel flange is, as described above and with reference to Figure 4B, created by rotating a region R2 relative to region Rl. Because the rotated material is forming a portion which is coupled to a hollow body it is generally provided with a constant circumference. This is illustrated in Figure 4C where the three circumferences CI, C2 and C3 are all constant. It will be recognised that the three circumferences are constant in this embodiment because the body has a constant cross-section. In a barrel application the circumferences might vary.

Figure 5 A shows a flange forming tool for forming a barrel flange. The tool illustrated in figure 5 A is adapted to create an inwardly folding flange so as to create a part as shown in Figure 5B comprising a flange 19. Here the flange is rotated inwards to define the inner flange (termed a barrel flange).

The following describes the formation of a barrel flange:

As shown in figure 5 A the flange forming mandrel comprises peaks 17 and troughs 18 i.e. the tool is provided with a non-uniform and undulating surface onto which the unidirectional composite tapes/plies 20 can be applied. Figure 5 A also illustrates the increase in amplitude of the sine wave from a point immediately adjacent the mandrel boundary 21 to the inner extent of the composite tapes 22.

Composite material is applied to the flange forming mandrel using an AFP machine which moves in a circular motion relative to the mandrel laying the tape. The tape is first layed-up against the mandrel on the first pass and then subsequently on proceeding layers to form a composite stack. The AFP machine lays the composite tape in a circular motion closely following the contours of the sinusoidal profile of the tool.

Figure 6 is a cross-sectional view through A- A' in figure 5A. As shown the mandrel has an undulating profile starting from height h of zero on the boundary 21 and progressively increasing at hi, h 2 and h 3 . Three tapes (for illustration only) of composite material t 1 ; t 2 and t 3 are also shown in figure 6. These tapes are layed-up around the mandrel as shown in figure 5 A.

As discussed above, and with reference to Figures 4C and 5B, for a barrel flange formation the circumference at each point CI, C2 and so forth along an x direction of the flange will have the same circumference i.e. CI = C2 = C3. This applies where the barrel portion of the flange has a uniform cross-section. For a non-uniform barrel the variables will correspond to the desired circumferences and the sine wave adapted accordingly.

Thus in order to form the flange the same length of composite material (tape) must be layed-up to create the circumference at each position C ls C 2 ... once the flange is formed. This means that each tape t 1; t 2 and t 3 must have the same length i.e. a length equal to the circumference of the desired barrel.

Figure 7 is a plan view of the flange forming tool of Figure 5 A.

Referring to figure 7 it can be seen that as the tape paths move towards the centre of the tool the path length decreases i.e.

Path length ti = 2πτι

Path length t 2 = 2πτ 2

Path length t 3 = 2πτ 3 Thus, as tape is layed-up toward the centre of the mandrel the circumference available to accommodate the length of tape required to define the circumference of the barrel is reduced.

In order to accommodate the fixed circumferential length of the barrel the undulating tool surface is adapted so that at each position the overall path length of the tape is substantially constant. This is achieved by progressively increasing the amplitude of the sine wave towards the centre O of the tool. Thus, the overall length of the material making up the tapes ti, t 2 and t 3 can be constant. In effect the same length of composite material is compressed into a reduced circumference by using an undulating sine wave profile.

Such an arrangement allows the barrel flange to be formed as shown in figure 5B. Figure 8 shows the composite flange component located within a pre-form blank 23 which is a ring arranged to support the flange whilst the undulating composite material is formed into its final position. The composite material is in a pre-cured state and so it is necessary to support the flange before it is formed and then cured. As shown in figure 8 the central sinusoidal tool portion has been removed leaving the composite material and blank 23.

The composite material may be moved into its final position using a variety of methods. For example a manual process may be employed where an operative manually pushes the undulating composite material 24 (shown in Figure 8) into contact with the vertical tooling region 25. To increase production an automated method may more preferably be employed. A mechanical press, roller, airbag or other arrangement may be used to move the composite material into alignment with the tooling. A rotary movement of the mechanism may advantageously be used to fold the material into position in a smooth and continuous manner.

The flange may be cured alone by means of heated tool, autoclave or out of autoclave techniques. The flange may then be coupled to the barrel/fan case or other component to which it is to be connected.

Alternatively the flange may be co-cured with the fan case barrel to which it is to be connected. In such an arrangement the barrel portion of the flange may be connected to the barrel of the fan case by means of a scarf joint for example and the two components co-cured together to form the consolidated part.

Radially Extending Flange

With reference to Figures 4D and 4E, in a radially extending flange embodiment the flange is formed by rotating composite material outwards to form the flange.

In contrast to the creation of a barrel flange where the circumference of the composite tapes forming the barrel remains the same, in a radial flange arrangement the composite material forming the flange increases in length with the flange circumference i.e. the length and area covered by the tapes increases. Figure 9 is an end view of the flange in Figure 4E showing, for illustration only, two tapes of composite material t t and t 2 . The length of composite material forming the first tape ti is 2π \ and the length of composite material forming the second tape t 2 is 2π¾. It will be recognised that the length of composite material forming the second tape is longer than the length forming the first tape. Thus, as the flange increases in radius the length of composite material required to form each progressive ring of the flange increases with increasing diameter. In order to accommodate the required increase in composite material the mandrel for forming the flange is provided with an undulating surface and more specifically a sinusoidal undulating surface.

Figure 4D illustrates the undulating sinusoidal profile of the composite material which is required to form the radially extending flange. As shown in Figure 4D the sinusoidal profile increases in amplitude towards the distal part of the flange. The amplitude of the sine wave is selected so that the overall path length of a composite tape applied at a particular position is substantially equal to the corresponding circumference of the tape when it has been moved into the radially extended position.

Figure 10 shows an arrangement where a radially extending flange mandrel and a fan case mandrel are integrated. The mandrel comprises a a barrel region 13 which is used to form the barrel of the fan case. On the end of the barrel region 13 a flange forming region 14 of the mandrel is provided. As shown the region 14 is formed of a non-uniform and undulating profile extending from an abutment 15 with the barrel region to a distal edge 16 defining the end of the mandrel. The undulating region 14 is specifically formed of a sinusoidal profile comprising peaks 17 and troughs 18 in a sine wave. It can be seen that the amplitude of the sine wave increases from the abutment 15 to the distal edge 16. This allows a fan case barrel and the flange to be layed-up together before they are cured.

It will be appreciated that in both the barrel flange forming embodiment and the radially extending flange forming embodiment a tool or mandrel is adapted so as to provide a lay-up surface allowing sufficient material to be layed-up to create the respective flange.

In the instance of a barrel flange the composite material required to make the barrel is, in effect, compressed into the available area of the tooling using the undulating sinusoidal profile.

In contrast, in the radially extending flange embodiment, the sinusoidal profile increases the surface area available for laying-up the composite material so that sufficient material can be layed-up to form the radially extending flange.

In each case the predetermined profile of the mandrel or flange may be detennined through various means for example by trial and error, automated computer aided design or by calculation. In each case the required area of composite material needed to form a given flange is determined and the profile of the mandrel or tool adapted to correspond to the desired area. This thereby provides a lay-up surface sufficiently large to allow the flange to be formed without applying a tensile load to the composite fibres. It will be recognised that although a sine wave has been described herein other mathematical profiles might equally be used and applied to a mandrel or tooling to form a flange portion.

There has been described a mandrel for forming a composite component, said component comprising a hollow body and a flange on one or both ends thereof; the mandrel comprising: a first region for forming the hollow body of said component and having a circumferential surface corresponding to the desired inner circumferential surface of the hollow body; and a second region on one or each end of said mandrel for forming the or each flange of said component, wherein the second region comprises a non-uniform and undulating surface.

There has also been described a tool for forming a composite component, said component comprising a flange portion and a hollow body portion; the tool comprising: a first circumferentially extending region for forming a flange surface; and a second region disposed within the first circumferentially extending region for forming the hollow body portion; wherein the second region comprises a non-uniform and undulating surface. Still further there has been described a method of manufacturing a composite component uses the above described tool and mandrel.