CROSS REFERENCE TO RELATED APPLICATION

The present application claims the benefit of United Kingdom Patent Application No. 1502323.7 filed Feb. 12, 2015, the contents of which are incorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION

The present invention concerns a tool for curing a composite component, the tool comprising a lay-up surface for laying-up layers of an uncured composite component. The invention also concerns a method of manufacturing a composite component and a composite component. The composite component may form at least part of a piece of aircraft furniture, such as an aircraft seat shell.

Seat shells for aircraft are often manufactured using composite laminate materials. The reason for using composite materials in the structure mostly is due to its lightweight and superior strength-to-weight properties of the material. These composite materials could be monolithic or sandwich composite laminates or a combination. The constituent materials for monolithic composite laminates are pre-impregnated materials (prepregs of resin impregnated fibres) whereas for sandwich composite laminates they are prepregs and a core material (e.g. honeycomb, foam). Honeycomb materials are preferable as a core material. Prepregs may be made with glass and/or carbon fibres impregnated with thermoset resin (e.g. phenolic or epoxy resin). The honeycombs core may be made with aramide based paper. Prepregs are often stored in freezers to ensure they are kept under the correct conditions.

The composite materials are prepared in a clean room by laying up the prepregs (and cores) on a mould tool at room temperature. After being layed-up the composite materials are bagged up using a polytetrafluoroethylene (PTFE) release film (if required), a rubber intensifier layer (to enable a uniform pressure to be applied on the composite component), a breather layer (to absorb excess resin) and then nylon bagging materials. A vacuum is then applied through a port in the nylon bagging (known as de-bulking). The mould tool with these bagged up materials is transferred to an oven or autoclave where the materials are connected to a different vacuum port and taken through a heating cycle (typically, heating to 135° C. and remaining at that temperature for a certain period of time depending upon the prepregs, typically 1 hour for phenolic resin prepregs) to cure the material. The materials are allowed to cool down to room temperature before extracting the cured and moulded laminate off the tool.

Following the curing of the material, the moulded part is machined into the required shape and profile as per the engineering design and then passed through an assembly line to attach metal and plastic bonding attachments, cushions and electrical components to complete the seat structure for the aircraft.

This process has many disadvantages. For example:1) The process can be very long, and therefore expensive, due to operating and man power costs. For example,a. Laying-up of the part can take up to 1.5 days due to the difficulties in laying-up prepregs, particularly when it is required to drape them over complex curved profiles.b. Moving layed-up composites in and out of the oven or autoclave can take 4 to 5 hours, due to the number of different components being cured in the oven or autoclave at once, and the need to attach each to its own vacuum supply in the oven or autoclave. Also, other components cannot be moved into or out of the oven or autoclave during the curing process, meaning there is a significant lead time in waiting for the oven or autoclave to be empty.c. The curing process can take 3 hours as the oven or autoclave can take a while to heat up to the desired temperature.d. CNC machining of the cured composite component can take up to half a day but the lead time in waiting for a machine may be half to 1.5 days.e. CNC (and other) machining of the cured component can produce a lot of dust, which needs to be extracted using a dust extraction system.f. It is time-consuming to apply the nylon bagging as it needs to be carefully sealed each time, using a sealant.g. Transferring the component to and from the CNC machine takes time.2) The nylon bagging is not reusable and so creates waste.3) An oven or autoclave is expensive and takes up a lot of space.4) Laying-up may require the use of separate heating ovens, guns or blankets.5) Separate vacuum supplies are required for de-bulking and during curing in the autoclave.6) The process consumes a lot of energy and the equipment requires a large amount of maintenance.

The present invention seeks to mitigate the above-mentioned problems. Alternatively or additionally, the present invention seeks to provide an improved tool for curing a composite component.

SUMMARY OF THE INVENTION

The present invention provides, according to a first aspect, a tool for curing a composite component, the tool comprising a lay-up surface for laying-up layers of an uncured composite component, a cover assembly for moving in relation to the lay-up surface to cover a layed-up uncured composite component on the lay-up surface, the cover assembly comprising a sealable cover for sealing around the uncured composite component on the lay-up surface to form a sealed zone, and a vacuum port for providing a vacuum to the sealed zone, wherein the tool further comprises at least one heating element within the sealed zone for heating the uncured composite component.

Providing a tool with an “in-built” heating element allows the layers of uncured composite to be layed-up onto a warm lay-up surface, making lay-up quicker. There is also no need for separate and/or time-consuming heating equipment, such as a heating gun, oven or blanket.

In addition, the tool can be used for the curing process. The tool heats up more quickly to the desired temperature than an oven or autoclave, as the heat is provided within the sealed zone. The volume to be heated is also a lot smaller than the volume of a typical oven or autoclave.

The tool also takes up much less space and is cheaper than a typical autoclave. Typically, the tool may be portable and may be provided with holes for allowing it to be lifted by a fork-lift, or similar.

In addition, providing a moveable cover assembly and sealable cover allows a seal to be established around the uncured component quickly and easily. It does not require a separate sealant.

Further, there is no movement of the tool into and out of an oven or autoclave required. Also, the same vacuum source can be used for both de-bulking and curing.

The layers of the uncured composite component are typically prepregs layers. The composite component may be a monolithic or a sandwich component.

The lay-up surface may be formed of a composite material, such as a carbon fibre composite.

Preferably, the cover assembly comprises a cover heating element for heating an upper side of the layed-up uncured composite component.

More preferably, the cover heating element is attached to an underside of the sealable cover.

Preferably, the cover assembly is provided with an insulating layer (above the cover heating element) to prevent heat from the cover heating element escaping out of the cover assembly.

Preferably, the cover heating element comprises a heating blanket, for example formed of a wire mesh, or similar, embedded within a carrier material.

Preferably, the lay-up surface comprises a surface heating element for heating a lower side of the layed-up uncured composite component. This surface heating element could also be used to warm the layers during laying-up by heating the surface above ambient temperature. For example, the surface could be heated to a temperature of 40 to 50° C.

More preferably, the surface heating element is embedded beneath a top layer of the lay-up surface.

Providing heating elements on the upper and lower sides of a composite component allows more even heating and a more uniform composite structure.

The tool preferably further comprises a vacuum source, such as a vacuum pump, connected to the vacuum port.

Preferably, the vacuum port is provided in the cover assembly.

A vacuum port may, additionally or alternatively, be provided at the lay-up surface.

Preferably, the sealable cover is a shaped cover that holds its shape. The sealable cover therefore has a volume associated with it for containing the uncured composite component.

More preferably, the sealable cover is shaped such that it has a lower edge region that can seal around the lay-up surface and a roof region that holds its shape to extend above the lay-up surface.

Preferably, the sealable cover is movably mounted (for example, with a hinge) in relation to the lay-up surface.

Alternatively, or additionally the sealable cover is movably mounted to the tool.

Preferably, the sealable cover is supported by a frame structure. The frame makes the sealable cover easier to move and provides a guide to move the sealable cover over the lay-up surface (to move it on to or off from the lay-up surface).

The frame may comprise a hinge to enable the sealable cover to be pivoted over the lay-up surface. The frame structure may comprise a gas strut to aid lifting/pivoting up of the frame and/or to maintain the frame and sealable cover in a position away from the lay-up surface, for example during lay-up. The frame structure may be provided with at least one handle. This aids with control of moving the frame and the cover.

Preferably, the sealable cover is made of flexible material such that it flexes when the vacuum is provided to the sealed zone.

More preferably, the sealable cover is made of an elastomeric material. For example, the sealable cover may be made from a silicon based elastomeric material, such as one called Viton™.

Preferably, the tool further comprises a cooling apparatus for cooling the composite component. This allows the component to be cooled, and therefore removed earlier, from the tool. This reduces the tool time for the component and allows more components to be cured in a given time period.

More preferably, the cooling apparatus is located in the frame structure.

Even more preferably, the frame structure comprises a plurality of air outlets from which cooling air may be expelled.

Preferably, the frame structure comprises an internal airflow channel through which cooling air passes.

Preferably, the tool comprises a vortex tube for supplying cooling air.

Preferably, the lay-up surface comprises a main surface portion, provided with a number of attachment points for attaching raised portions on the main surface portion.

Preferably, the lay-up surface comprises a main surface portion and a number of raised portions on the main surface portion.

The raised portions provide a required geometric profile to allow the layers to be layed-up and layers to abut against the raised portions so that the same required profile of the component is achieved. The required profile may be an edge with, for example, a castellated shape or may be an internal hole and/or recessed area within the component. A raised portion may comprise a dowel (for example, made of nylon) for providing a hole in the component, for example, for a rivet or other fastener.

Preferably, the raised portions comprise through-holes for attaching the raised portions to corresponding attachment points on the main surface portion. The raised portions may be attached with fasteners, such as bolts.

The tool may be provided with sensors to sense the temperature and/or pressure inside the sealed zone.

The tool may also be provided with a data recorder to record the temperature and/or pressure inside the sealed zone. The data recorded may be able to be transferred to a portable data storage device for transferring to a computer or a similar tool. The second tool may then provide the same temperature and/or pressure profile during another curing process on another component. Having a set temperature and/or pressure profile associated with the curing of the components may aid in authentication or certification of the components.

The tool may be provided with a control panel that controls the tool to provide a required temperature and/or pressure. The control panel may be a programmable interface device (such as a proportional-integral-derivative controller, for keeping the heating and cooling rates constant) to allow the tool to provide a require temperature and/or pressure profile during curing.

According to a second aspect not of the invention there is also provided a tool for curing a composite component, the tool comprising a lay-up surface for laying-up layers of an uncured composite component, and a cover assembly for moving in relation to the lay-up surface to cover a layed-up uncured composite component on the lay-up surface, the cover assembly comprising a sealable cover for sealing around the uncured composite component on the lay-up surface to form a sealed zone, wherein the sealable cover comprises a shaped cover that holds its shape.

The sealable cover therefore has a volume associated with it for containing the uncured composite component.

Preferably, the sealable cover is shaped such that it has a lower edge region that can seal around the lay-up surface and a roof region that holds its shape to extend above the lay-up surface.

Preferably, the sealable cover is supported by a frame structure. The frame makes the sealable cover easier to move and provides a guide to move the sealable cover over the lay-up surface (to move it on to or off from the lay-up surface).

The frame may comprise a hinge to enable the sealable cover to be pivoted over the lay-up surface. The frame structure may comprise a gas strut to aid lifting/pivoting up of the frame and/or to maintain the frame and sealable cover in a position away from the lay-up surface, for example during lay-up. The frame structure may be provided with at least one handle. This aids with control of moving the frame and the cover.

Preferably, the tool further comprises at least one vacuum port for proving a vacuum to the sealed zone and wherein the sealable cover is made of flexible material such that it flexes when the vacuum is provided to the sealed zone.

More preferably, the sealable cover is made of an elastomeric material. For example, the sealable cover may be made from a silicon based elastomeric material, such as one called Viton™.

Preferably, the sealable cover and/or cover assembly are made of durable materials. This allows them to be re-used.

According to a third aspect of the invention there is also provided a tool for curing a composite component, the tool comprising a lay-up surface for laying-up layers of an uncured composite component, wherein the lay-up surface has a main surface portion and wherein the main surface portion is provided with a number of raised portions on the main surface portion, and/or a number of attachment points for attaching raised portions on the main surface portion.

The raised portions provide a required geometric profile to allow the layers to be layed-up and layers to abut against the raised portions so that the same required profile of the component is achieved. The required profile may be an edge with, for example, a castellated shape or may be an internal hole and/or recessed area within the component. A raised portion may comprise a dowel (for example, made of nylon) for providing a hole in the component, for example, for a rivet or other fastener.

Preferably, the raised portions are removable from the main surface portion to aid laying-up of the composite component to and/or extraction of the composite component from the lay-up surface.

Preferably, the raised portions comprise through-holes for attaching the raised portions to corresponding attachment points on the main surface portion. The raised portions may be attached with fasteners, such as bolts.

Preferably, the raised portions comprise an attachment device that projects outwardly from the raised portion in a direction away from the main surface portion. The attachment device can be used to secure an insert in the composite component.

More preferably, the attachment device is a split pin. This allows one or more layers of the uncured composite component to be cut in the split of the pin.

Preferably, the attachment device comprises a pluck-out hole, into which a tool can be inserted in order to pluck-out the raised portion from the main surface portion.

Preferably, a surface of the raised portion comprises a cutting guide groove. This facilitates the cutting of one or more layers of the uncured composite component, as a cutter may be placed in the groove and moved along the groove to cut the layers.

Preferably, either the raised portion comprises a biased retaining stud that is biased to project outwards from the raised portion, such that it may be retained in a stud-receiving recess in the main surface portion, or the raised portion comprises a stud-receiving recess for receiving a biased retaining stud that is biased to project outwards from the main surface portion. This allows for the raised portion to be secured in the main surface portion but also allow it to be efficiently removed.

More preferably, the stud-receiving recess or biased retaining stud of the main surface portion is located in a socket and the wall of the socket or the wall of the raised portion acts as a cam that exerts force on the stud as the raised portion attached to the main surface portion.

According to a fourth aspect of the invention, there is also provided a tool for curing a composite component, the tool comprising a main body and a lay-up surface portion for laying-up layers of an uncured composite component, wherein the lay-up surface portion is removable from the main body of the tool. This allows the lay-up surface portion to be removed and replaced with a different lay-up surface portion. This allows the tool to be used to manufacture a number of different shaped components.

Preferably, the removable lay-up surface portion comprises an electrical connector and the main body comprises a corresponding electrical connection point. This allows the lay-up surface portion to be provided with electricity, for example for powering a heating element.

Preferably, the removable lay-up surface portion comprises a vacuum port connector and the main body comprises a corresponding vacuum port. This allows the lay-up surface portion to be provided with a vacuum supply.

Preferably, the removable lay-up surface portion comprises alignment members and the main body comprises corresponding alignment members, to allow the removeable lay-up surface portion to be aligned with the main body.

According to a fifth aspect of the invention there is also provided a method of manufacturing a composite component, the method including the steps of laying-up an uncured composite component on the lay-up surface of the tool of any preceding claim, curing the composite component, and extracting a cured component from the lay-up surface.

The curing process may involve the steps of heating the uncured composite component and also providing a vacuum to the uncured composite component.

According to a sixth aspect of the invention there is also provided a composite component manufactured by the method described above.

Preferably, the composite component forms at least part of a piece of aircraft furniture, such as an aircraft seat shell.

It will of course be appreciated that features described in relation to one aspect of the present invention may be incorporated into other aspects of the present invention. For example, the method of the invention may incorporate any of the features described with reference to the apparatus of the invention and vice versa. Also, features described in relation to one aspect of the apparatus of the present invention may be incorporated into other aspects of the apparatus of the present invention.

