GB2619706A

GB2619706A - Carbon fibre shell

Info

Publication number: GB2619706A
Application number: GB2208431.3A
Authority: GB
Inventors: James Mcculloch Finlay
Original assignee: Bayerische Motoren Werke AG
Current assignee: Bayerische Motoren Werke AG
Priority date: 2022-06-09
Filing date: 2022-06-09
Publication date: 2023-12-20
Also published as: GB202208431D0

Abstract

Carbon fibre shell 101 comprises an exterior surface, an interior surface and an internal cavity, at least one layer of carbon fibre; a bonding material within the matrix of the carbon fibre; and at least one layer of lacquer 103 applied to all or a portion of the exterior surface. An additional feature of a flange or skirt 109 of carbon fibre material extending around all or a portion of the circumference of the mouth of the internal cavity. A method comprises laying up at least one layer of carbon fibre in the cavity of a female mould, the mould including a circumferential flange, applying bonding material to the carbon fibre layer, applying pressure, removing the carbon fibre shell from the mould and lacquering part or all of the external surface of the shell. The pressure may be applied by a vacuum bag system. The shell may include at least one layer of wood veneer mounted on the exterior surface, apertures through the shell and fixing means for attachment to a subassembly of a vehicle. The products of the invention are suitable for use in automotive interiors and such as facias, instrument panels and armrests of automobiles.

Description

Carbon Fibre Shell The present invention relates to the production of carbon fibre shells that may be further modified or adorned by the addition of layers of lacquer, veneer, and/or paint thereto. The present invention also relates to methods for producing products of the invention and intermediate products made in the course of those methods. In addition, the invention also considers use of methods, products, and apparatuses of the invention in automobile manufacture and maintenance. In particular, the products of the invention are suitable for use in automotive interiors and such as facias, instrument panels and armrests of automobiles.

The advantageous properties of carbon fibre have long been recognised in the automotive sector. The likeness and strength of this composite material has lent itself to many roles in the construction of vehicles such as automobiles, aeroplanes and boats Carbon fibre is a composite material made of aligned or underlined fibres of carbon material arranged in a laminar layer and then stabilised or fixed in position by the addition of a bonding agent, typically a resin compound that is incorporated in the pores and other voids of the laminar fibrous material in order to stabilise and fix its three-dimensional form. In this way carbon fibre can be "laid up" by applying it in layers to a mould and then impregnating or otherwise introducing the bonding material to the layers so formed. In this way, complex three-dimensional laminar forms can be produced. Frequently, such three-dimensional objects made with carbon fibre have most advantageous strength:weight ratios, making them particularly suitable for inclusion in vehicles and automobiles, be they powered such as automobiles (cars), aeroplanes and boats, or unpowered, such as pedal cycles (e.g. bicycles), sailing vessels and skateboards.

Unadorned carbon fibre is frequently visible in these applications. However, aesthetic considerations will often require that the service be further adorned with covering or capping layers. These layers may comprise wood veneer of various types, paint and/or a lacquered surface. These additional layers also function to protect the -2 -underlying carbon fibre and yields surfaces that are simpler or easier to clean and/or polish.

Hitherto, typically structures in an automobile interior adorned with wood veneers are manufactured by sandwiching 0.4 millimetre (mm) veneer layers (typically made of tulip wood) of 0.4mm are sandwiched with aluminium layers of 1 mm thick and intervening layers of adhesive to create a series of sublayers (e.g. tulip veneer, glue sheet layer, aluminium sheet, glue sheet layer, tulip veneer, etc.) A face veneer, which is not necessarily tulip wood and, indeed, may be one of a vast variety of different wood veneers that is available, is visible on the outermost layer of the stack.

One known method for manufacturing such a structure comprises adding the layers of material described above to a tool with a cavity wherein the interior of the cavity provides a receiving/moulding surface. A cooperating and substantially matching convex mould structure is then added to the stack and pressure applied in order to push the intervening layers of material into the space defined between the two faces of the mould. Thus the shape of the layers is formed into the correct shape and geometry between the moulding surfaces. The cooperating in substantially matching convex mould structure is, typically, a plastic "carrier." In this case a carrier is a substructure with the various fixtures required for locating and securing the substructure in a larger product, e.g. a car. Such carriers are normally made of injection moulded plastics material.

The particular purpose of the aluminium layers in the structure is to hold the form of the structure stably and give the structure structural integrity during the milling and cutting processes that are necessary for finishing the moulded product so that it can be mounted in a vehicle. During these processes changes in the geometry and/or form of the product needs to be prevented otherwise the part and/or subassembly cannot be successfully mounted in the larger product, e.g. a vehicle.

This is particularly the case for parts that are lacquered. This is either for gloss lacquer of surfaces or lacquered wood surfaces because the lacquer dries out and contracts -3 -as it cures and thus applies significant tension to the surface of the part to which lacquer is applied. However, in the case of the stacked laminar structure described above, such bending is resisted and prevented by the aluminium layer(s). Without that layer or layers, the force generated by curing of the lacquer layer would yield either misshaping or cracking of the lacquered layer. The lacquered layer needs to be perfect for aesthetic reasons and the interior car part structure must also maintain its integrity as warping its form would mean that it could not be fitted directly into the larger product, such as a car directly in the car.

Parts in a vehicle that require adornment with a layer of veneer, but must also resist warping and have a stable form in order to ensure reliable installation and use, are currently manufactured using the process described above. Such parts include many sections of the interior trim of automobiles, including the fascia, i.e. the section of bulkhead in a car located in front of the passenger but also extending to the areas of the dashboard surrounding the instrument mounting section, dashboard, instrument panels and armrest sections.

The process above for producing the veneered part is reliant on the structural strength and resilience of the overall assembly that is yielded by the aluminium layers and the carrier structure. Necessarily, there are significant costs in making the tooling required, both for shaping the product and the cost of tooling for producing the injection-moulded carrier. Thus such tools are only economic if the products they are designed for produced at scale. Necessarily, this means that production of bespoke items or in limited quantities is normally prohibitively expensive. Similarly, production of replacement parts for which the tooling is no longer available is also prohibitively expensive.

Accordingly, there is a need for a process that is capable of producing bespoke products and/or low-volumes of particular products at a lesser cost than would be required for the extensive tools required for a vehicle produced in larger quantities.

However, this new process must also produce products, parts and structures that are similarly durable to products produced using previous methods, and are thus suitable for passing the safety inspections required for their for inclusion in vehicles. -4 -

It is therefore an object of the invention to provide a method of producing lacquered automotive parts that are suitable for mounting and/or installing in a vehicle, which requires less extensive tooling to manufacture the products.

The invention provides a carbon fibre shell having an exterior surface, an interior surface and an internal cavity comprising: at least one layer of carbon fibre; a bonding material within the matrix of the carbon fibre; and at least one layer of lacquer applied to all or a portion of the exterior surface.

The invention further provides a method of manufacturing a carbon fibre shell having an exterior surface, an interior surface and an internal cavity comprising the steps of: laying up at least one layer of carbon fibre in the cavity of a female mould wherein the mould comprises a circumferential flange around part or all of the mouth of the internal cavity; applying bonding material to the carbon fibre layer in the mould; applying pressure to the surface of the carbon fibre layer; removing the carbon fibre shell from the mould; and lacquering part or all of the external surface of the carbon fibre shell.

The invention also provides intermediates that may be produced by a method of the invention and then further processed to yield products of the invention. Thus the invention provides a carbon fibre shell having an exterior surface, an interior surface and an internal cavity comprising: at least one layer of carbon fibre; a bonding material within the matrix of the carbon fibre; at least one layer of lacquer applied to all or a portion of the exterior surface; and a flange or skirt of carbon fibre material extending around a portion of the circumference of the mouth of the internal cavity.

As used herein the term "A" surface is the surface that faces the user/customer and the term "B" surface refers to the surface that faces the inside of the car away from the -5 -user. Necessarily the B surface does not need to be as aesthetically pleasing as the A surface.

The terms "carbon fibre" and "carbon fiber" are synonymous and are used interchangeably herein. The products of the invention may comprise a single or multiple layers of carbon fibre material. Preferably, products of the invention comprise a single or multiple layers of carbon fibre material.

A bonding material in the context of the present invention may be a resin, glue or other adhesive. A bonding material is typically a liquid, semiliquid or paste/pliable material that cures to form a structurally stable solid material. Accordingly, a broad range of synthetic or natural materials may be considered bonding materials in the context of the present invention. In particular, a bonding material may be used as a component of a composite material, such as composite carbon fibre material, by the bonding material being used to fill the interstitial spaces within the carbon fibre material. Such composite carbon fibre material is preferably of sufficient strength, thickness and/or geometric stability (i.e. resistance to deformation) so to comply with the engineering requirements for installation in vehicles, including automobiles.

A particular advantage to the methods of this invention, and hence the products produced thereby, is that no male mould/tool is required for the initial process of laying up and shaping the carbon fibre shell. Producing such paired male-female tools is expensive, especially when there is no need for the absolute level of geometric and spatial control in the form of the "B" surface. This is especially the case when the B surface will be invisible during use of the product Preferably the interior of the internal cavity is substantially uninterrupted by members or webs of material extending from the shell that extend through the cavity space. More preferably, the interior of the internal cavity is not interrupted by members or webs of material extending from the shell that extend through the cavity space. Most preferably the interior of the shell is substantially hollow.

Hollow in this context is defined as empty and without webs or additional members occupying a significant volume of the interior of the shell. The advantage of such as -6 -configuration within the shell is that this lack of complexity in conjunction with the "B" side being effectively flat is that a male tool made to fit the cavity can be made much more simply and thus more efficiently than carriers produced for parts with more complex B side configurations.

Furthermore, the strength and structural integrity of the carbon fibre shell of the present invention, as compared with the laminated material strengthened with aluminium layers, means that there is a reduced requirement for strengthening veins and webs, to be moulded into the "B" surface in order to maintain the structural integrity of the part. However, in the present invention, the "B" surface is largely featureless and thus the male tool for holding and processing the part is much simplified for the present invention as the indentations and other matching cut outs need not be produced in the tool.

The carbon fibre shell may also comprise one or more layers of lacquer on the exterior surface. Preferably, a multiplicity of layers of lacquer are applied to the exterior surface. Most preferably, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13,14,15, 16, 17, 18, 19, or 20 layers are applied to the exterior surface. Typically the lacquer layers are allowed to dry or cure between separate applications.

Lacquering is defined as the process of applying a layer of a sealing material to a surface in order to give a glossy and/or sleek "finish." Typically, a layer of lacquer is smooth and impervious. Natural forms of lacquer are known, including the original glossy, resinous material, used as a surface coating that is obtained by processing the sap of the lacquer tree. However, in the present context lacquer includes a wide variety of substances used to impart a high gloss to surfaces. Thus, the term lacquer encompasses any of the various clear or coloured synthetic coatings used to impart a high gloss to surfaces including those made industrially by dissolving nitrocellulose or other cellulose derivatives together with plasticizers and pigments in a mixture of volatile solvents that are typically used to impart a high gloss to surfaces.

The curing process of lacquer by which the liquid component of the lacquer upright reply to a surface is removed, mostly by evaporation, causes the lacquer layer to contract. A particular advantage of the present invention is that a carbon fibre shell -7 -produced according to the present invention is able to resist/withstand the contracting force without significant deformation. Furthermore, products made of lacquered composite carbon fibre material as described herein are preferably of sufficient strength, thickness and/or geometric stability (i.e. resistance to deformation) so to comply with the engineering requirements for installation in vehicles, including automobiles.

The flange or skirt of material may extend around all or a portion of the circumference of the mouth of the cavity. Preferably the flange or skirt of material extends around a portion of the circumference of the mouth of the cavity.

This additional material of the flange or skirt can be removed from the finished product. Typically this material may be machined away, preferably by milling. However, this additional material provides the intermediate product with an edge structure that acts as a web in order that the intermediate product can resist deformation (bending or twisting) during manufacture. The additional material can also be used to strengthen the final product by only machining away selected portions of the additional, web material.

Accordingly, the flange or skirt of material may be substantially at right angles to the plane of the mouth of the internal cavity. Preferably the flange or skirt of material forms a box section along all or part of the circumference of the mouth of the cavity.

The flange may be of variable height. Alternatively, the flange may be of constant height.

The carbon fibre shell may also comprise one or more layers of veneer affixed, attached or mounted on the exterior surface beneath the lacquered exterior surface. Thus the veneer layer(s) preferably conforms to the exterior surface contours of the shell. Preferably one layer of veneer is so used. Most preferably the veneer is a wood veneer.

The outermost layer of veneer is termed the "face veneer". Typically the face veneer is 0.55 mm thick. However, the thickness of the face veneer can vary due to -8 -manufacturing tolerances. Thus the face veneer may be 0.4 mm, 0.45 mm, 0.5 mm, 0.55 mm, 0.6 mm, 0.65 mm or 0.7 mm thick.

Thus, the thickness of the face veneer may contribute to the total thickness of the carbon fibre shell.

The thickness of the carbon fibre layer(s) and lacquer layer(s), along with the depth of the optional veneer layer (which is preferably a face veneer layer) contribute to producing the total thickness or depth of the carbon fibre shell. Thus the carbon fibre shell may be manufactured to be a desired thickness. This desired thickness may be, 1 mm thick, 2 mm thick, 3 mm thick, 3.5 mm thick, 4 mm thick, 4.5 mm thick, 5 mm thick. . Preferably, the carbon fibre shell is manufactured to be 3.7 mm thick.

Substantially any form of wood veneer can be used in the context of the present invention. A non-exhaustive of veneer is set out below in the following list: Tudor Oak, Macassar Ebony, Oak Cluster, Paldao, Smoked Chestnut, Tuscan Ash Burr, Waterfall Bubinga, Oak Burr, Brushed Black Metal Fascia, Roman Oak, Rosewood, Royal Teak, Palisander Crown, Palisander Straight Grain, Silver Birch, Teak, Teak (Embellished), Smoked Eucalyptus, Rosewood, Ash Burr, Black Stained Ash, Mahogany Flare, Royal Walnut (Circassian Walnut), Royal Walnut, Walnut Burr, Black Stained Ash, Blackwood, Mimosa Negra, Silver Birch, Caleidolegno.

The product of the invention may comprise a layer of glue or adhesive between the carbon fibre shell and the layer of veneer. This yields greater structural stability to the finished product.

The carbon fibre shell may comprise fixing means attached to the shell for location and attachment of the shell to a further structure The further structure may be a subassembly of a vehicle. Preferably the subassembly is a carrier structure. The subassembly may be a carrier for inclusion as a component or subassembly in a vehicle dashboard or fascia.

The subassembly may be a carrier for inclusion as a component or subassembly in a vehicle door. The subassembly may be a vehicle armrest. -9 -

Preferably the carrier is produced by 3D printing. The advantage of using 3-D printing is that bespoke parts can be produced and thus the significant cost of tooling can be avoided, which is only economic when products are produced in significantly greater 5 numbers. The 3D printing method may be fused deposition modelling (FDM).

The carrier may be 3D printed using Nylon 12 CF material. Nylon 12 CF material comprises flaked carbon fibre material that is thus is included in the 3D printed product. Use of 12CF in 3D printing yields a product with greater strength in line with the planes of the 3D printed product. Thus, the product that is made is stronger than the standard plastics material typically used for 3D printing.

The carrier may be 3D printed using acrylonitrile butadiene styrene (ABS) material.

The fixing means for location and attachment of the shell to a further structure may be threaded rods. The threaded rod may be 10 mm, 15 mm, 20 mm, 25 mm, 30 mm, 35 mm, 40 mm, 45 mm or 50 mm in length. The threaded rod may be M3, M4, M5, M6, M8, M10 or M12 according to BS 3643 as based on ISO 965/1 and ISO 965/3 standards for metric screw threads. Preferably, the threaded rod is an M6, 10 mm threaded rod.

The fixing means may be mounted on a foot that is in turn attached to the shell. The attachment means for fixing the foot to the shell may be an adhesive or bonding agent. Thus the fixing means is easily available and conveniently attached accurately to the B-side of the carbon fibre shell. Thus, the potential disadvantages associated with not using a highly accurate injection moulded carrier are overcome by the use of such attachment means in concert with control features, i.e. a 4-way control feature located centrally on the part and two 2-way control features at either extremity of the part. Cooperative use of these three control features may be used to achieve 3-2-1 alignment across the parts. This thus yields accurate placement, alignment and installation of the pad on a carrier or in a larger assembly, e.g. a vehicle.

The carbon fibre or layer of carbon fibre may be in the form of a woven or non-woven sheet. Preferably the carbon fibre is in the form of a woven sheet. Most preferably the -10 -carbon fibre sheet is in the form of "2+2 Weave." The interstitial spaces between the individual carbon fibres in a carbon fibre sheet or within a laid-up assembly of carbon fibre material are referred to as the "matrix" of the carbon fibre assembly. This volume within the carbon fibre assembly is typically filled with air while assembly is taking place and, typically, the air is wholly or completely replaced with a bonding material during the manufacturing process. Hence, the production of carbon fibre composite material.

Preferably, the method comprises the additional step of allowing the resin or glue to 10 cure. The curing process may be under conditions of elevated pressure and/or temperature. Preferably the pressure is 1 atmosphere. Preferably the temperature is in the range 50-70 degrees Celsius.

The method may additionally comprise a step of applying pressure to the surface of the carbon fibre layer by inserting the assembly in a flexible, airtight bag or shroud and evacuating the volume therein such that part of the bag or shroud abuts the area of the carbon fibre layer in the mould.

This has the advantage of being simple to achieve and requiring less tooling in the 20 form of cooperating male -female moulding tools than are required in other techniques that are typically used.

The method may additionally comprise the step of reducing the height of the circumferential flange. Preferably this is carried out by milling away excess material.

Accordingly, the height of the circumferential flange may be reduced consistently or variably. As noted above, this has the advantage of maintaining the strength and structural integrity of the part that is conferred by the presence of the circumferential flange while accommodating design constraints by removal of the flange in areas where it is not structurally necessary.

In addition the method may additionally comprise the step of introducing apertures or other cut-out portions to the product. This is preferably done my machining and most preferably my milling. Pilot holes may be made in the product before any machining or milling is carried out.

An unexpected advantage been found during the milling process, i.e. while making apertures in the product. This is that, previously, for product produced using the previously known tulip/ aluminium stack and laminating method, there was a likelihood of there being cracking of the lacquer in areas between apertures milled out of the product. In contrast, products of the present invention are more resistant to such cracking of the lacquer in such areas, such as those located between apertures milled out of the product. While not wishing to be bound by theory, this may be because the vibration is better suppressed during the machining process of products of the present invention and thus less damage is caused to the lacquer. Accordingly, a greater resistance to vibration damage, or the suppression of vibration damage, allows for more extensive and/or more intense machining and so allows for the creation of lacquered products with more complex geometry than previously possible.

Products of the invention may be for use in a vehicle, furniture, or part of a building.

Preferably the product is for use in a vehicle, most preferably wherein the vehicle is an automobile or car. Advantageously, products of the invention and products produced according to methods of the invention have characteristics of sufficient strength and structural stability to comply with the engineering requirements for installation in vehicles, including automobiles.

Products of the invention may be for use in the interior or cabin of a vehicle. Preferably products of the invention are comprised in a vehicle headliner, ceiling panel, door, seat, armrest, wall, wall panel, flooring, floor panel, dashboard, instrument panel, or parcel shelf. Advantageously, products of the invention and products produced according to methods of the invention can comprise a variety of face veneers or other surface decoration in order to match and accommodate other elements within a vehicle cabin or interior.

Accordingly, the invention also provides a vehicle comprising a product of the invention. The vehicle may be an automobile, aeroplane or boat. Preferably the vehicle is an automobile.

-12 -Examples and Drawings The invention will now be described with reference to the following drawings and examples in which: Fig. 1 shows a perspective view of a completed facia for an automobile (bottom left) and an exploded view of subcomponents comprised in the completed facia (three components to the upper right). The carbon fibre shell 101 is adorned with face veneer that is further coated with layer(s) of lacquer 103. The carbon fibre shell 101 and veneer section 103 each have an additional flange or skirt of material 109 and 111, respectively. The veneer layer 103 and carbon shell 101 components are in turn installed on a 3-D-printed plastic carrier 105 in order to provide the facia assembly for an automobile 107. The material of the flange or skirt 109 111 is removed as necessary and apertures 113 made in the final facia assembly.

Fig 2 shows exploded views of subcomponents comprised in an armrest assembly for a vehicle door.

Fig. 2a Shows an exploded left-upper-front perspective view of subcomponents comprised in and armrest assembly for a vehicle door. Upper 201 and lower 203 carbon fibre shells adorned with face veneer that is further coated with layer(s) of lacquer are mounted on a 3-D printed plastic carrier 205. A chrome strip feature 207 is installed on the 3-D printed plastic carrier 205 between the opposing edges of the upper 201 and lower 203 carbon fibre shells.

Fig. 2b Shows an exploded right-upper-rear perspective view of subcomponents comprised in and armrest assembly for a vehicle door. Upper 201 and lower 203 carbon fibre shells adorned with face veneer that is further coated with layer(s) of lacquer are mounted on a 3-D printed plastic carrier 205. A chrome strip feature 207 is installed on the 3-D printed plastic carrier 205 between the opposing edges of the upper 201 and lower 203 carbon fibre shells.

Example 1

Fascia for an Automobile In order to manufacture a fascia for an automobile an aluminium female tool with a cavity that defines the outer contour of the part being made is first manufactured.

-13 -Layers of pre-ply followed by layers of carbon fibre matting material are laid up in the cavity to a total thickness of 1.3-1.5mm in total. However, the number of layers can be adapted freely in order to achieve a desired overall thickness that varies from this amount. The carbon fibre material in this example is "2+2 weave", however any carbon fibre laying-up fabric can be used.

The laying up is the process of adding carbon fibre material, preferably in sheet form to a mould or tool so that the material conforms to the shape of the mould or tool.

Bonding resin, glue or other adhesive is applied to the carbon fibre laid up in the mould/ tool either after or during the laying up process and then the assembly in placed inside a flexible enclosure (vacuum bag) and sealed therein. Extracting the air from the vacuum bag causes atmospheric pressure to be applied to the surface of the assembly. The bonding material is then allowed to cure.

The tool also has an additional flange or skirt of material in order to produce a box structure 109 on the edge of the product. This additional material can be machined away from the finished product. However, this additional material provides the intermediate product with an edge structure that acts as a web in order that the intermediate product can resist deformation (bending or twisting) during manufacture.

The additional material can also be used to strengthen the final product 107 by only machining away selected portions of the additional, web material.

The parts produced can be tested using photogrammetry in order to show that the final part is consistent with the shape of the original mould and that during manufacture the part had not deformed beyond the tolerances required for correct installation of the product.

Thus the base carbon fibre shell 109 is produced. This carbon fibre shell is then further processed and/or adorned in order to produce the finished product, as explained in more detail below.

-14 -Membrane process Thus, once the first base part (base carbon fibre shell) is made then a membrane process is used by which a male tool to fit the cavity in the carbon fibre shell is produced and the part is put on top with the "A" surface showing. Veneer and glue or another adhesive is then laid on top of this structure in order to stick the veneer in place. The resulting assembly is then placed inside a vacuum bag, sealed, and a vacuum applied in order that 1 atmosphere of pressure is brought to bear on the veneered surface while the adhesive cures. The curing process can take place at room temperature; however, the process is speeded heating the glue to 60-700 C in order that it cures faster.

Typically the veneer is 0.4 mm thick, however, other thicknesses are possible with veneers that are available. Furthermore, this process can be carried out with any available veneer.

A non-exhaustive of veneer is set out below in the following list: Tudor Oak, Macassar Ebony, Oak Cluster, Paldao, Smoked Chestnut, Tuscan Ash Burr, Waterfall Bubinga, Oak Burr, Brushed Black Metal Fascia, Roman Oak, Rosewood, Royal Teak, Palisander Crown, Palisander Straight Grain, Silver Birch, Teak, Teak (Embellished), Smoked Eucalyptus, Rosewood, Ash Burr, Black Stained Ash, Mahogany Flare, Royal Walnut (Circassian Walnut), Royal Walnut, Walnut Burr, Black Stained Ash, Blackwood, Mimosa Negra, Silver Birch, Caleidolegno.

A further advantage of the tool used in this membrane process is that the "B" side is effectively flat and has many fewer features than a carrier produced for a car that is manufactured in greater volumes. Such cars typically use a carrier that is injection moulded and necessarily there are various fixings and other veins and webs moulded into the "B" surface of the carrier in order to maintain the structural integrity of the part. However, in the present invention, the "B" surface is largely featureless and thus the male tool is much simplified for the present invention as the indentations and other matching cut outs need not be produced in the tool.

However, necessarily, the flat "B" side of the assembly must have some means of fixing it to the car. In this case, 'big head' fixings are bonded to the shell (these are M6 -15 -lOmm long threaded bolts with a foot (i.e. the 'big head') bonded directly to the shell. The threaded portions of the big head fixings are used to attach the part to the carrier subassembly.

While the carrier 105 can be made by conventional means, i.e. by injection moulding or similar, for low volume applications it can advantageously be made by 3D printing. Thus in this example carrier is 3D printed. Furthermore, the material used for printing is nylon 12CF (CF stands for carbon fibre and flaked carbon fibre is included in the 3D printing material; its inclusion this yields greater strength between the layers of the 3D printed product. Thus, the product that is made is stronger than the plastics material that is typically used for 3D printing.

Therefore, this stage has a particular advantage in that the male tool is very much simplified as it only needs to be made with indentations to accommodate the big head 15 fixings during the membrane process.

Sanding process Once the veneer layer is applied, the A surface is typically further prepared by sanding. For sanding the "A" surface, a further male tool is required in order to mount the product thereon. However, the simplification of the "B" surface means that a much less complex standing "fixture" is required to hold the product during the sanding process. This is a further advantage that parallels the advantage for the membrane process described above.

Lacquering process The exterior of the product is then lacquered using known processes. One example is the varnish and lacquering system manufactured by Votteler (Votteler Lackfabrik GmbH & Co. KG.) Carbon fibre weave In order that a decorative carbon fibre weave can be seen on the part from within the car a decorative layer of carbon fibre can be included at the first stage of construction in the laying up. This has the advantage of not requiring the membrane process or -16 -sanding process during manufacture. However, it is still necessary to go through the lacquering process, and the polishing process for the lacquer layer.

Painted finish The carbon fibre shell describe here has a particular advantage of being able to be painted directly onto the carbon fibre surface. Furthermore, the carbon fibre surface necessarily has a flat surface suitable for painting with minimal preparation and this is much more straightforward than preparing a wood veneer panel/part to be a paintable surface.

Miffing/Shaping The lacquered product is then milled to the final geometry. The shaping/milling process comprises drilling pilot holes and then milling out larger holes from this starting point.

A further fixture/tool is required to hold the product in place during the milling process.

In known processes, the complexity of the "B" surface of the assembly, i.e. the rear of the carrier component, required the fixture required to hold the product in place during the milling must also be complex to accommodate the complex 3D shape of the B surface. Accordingly, fixing the product to the fixture is necessarily also relatively complex and thus so is the process of removal of excess material.

In contrast with the present invention, the simplicity of the B surface of the shell means that a tool can be built to hold the product in place during milling using a vacuum system, as is commonly known in this realm of manufacturing. This is achieved by including a vacuum path in the milling fixture to hold the shell in place more simply and more conveniently. Accordingly, attachment, shaping and release of the part from the milling apparatus is simplified significantly.

Polishing Following final shaping the product is polished. A separate tool for polishing that engages with the "B" surface of the product. This tool is equipped with handles on the reverse side so that the operator can safely hold the work piece and directed it correctly while polishing it using mechanised polishing devices. The advantages of a -17 -less complex B surface that are described above in relation to the milling stage are also applicable at the polishing stage.

Bonding on carrier Once the component is completed then it is bonded onto the carrier 105.

Notably, the big head fixings attached to the shell are only for alignment of the part during fixation. Bonding is achieved with carbon fibre glue, and the final location of the part achieved by using control features, i.e. a 4-way control feature located centrally on the part and two 2-way control features at either extremity of the part. Cooperative use of these three control features is used to achieve 3-2-1 alignment across the parts.

Similarly for the other processes the shell is placed on the carrier and glue has/ will be applied before placing the assembly in a vacuum bag and evacuating it to apply a 1 atmosphere pressure on the assembly. At this case, no heat is used to assist curing of the glue/adhesive and the assembly is left overnight/8 hours under vacuum to complete the curing process.

Following this step the 4-way locator and thew 2-way locator are removed and reused for another assembly.

In contrast, the big head fixings remain in place. The part is now ready for mounting on an automobile.

Example 2

Doors for an Automobile A similar concept for the door inserts is for/ as for the dashboard/facias.

An exploded view of components comprised in door armrests for vehicles is shown in Figure 2. In contrast to the fascia component described in Example 1, above, the door arm rests comprise an upper shell 201 and a lower shell 203 attached to the upper and lower portions of a carrier 205.

However, the upper and lower shells are manufactured and attached to the carrier in the correct position using essentially the same process as for the fascia component described in Example 1.

-18 -However, in contrast the bonding process of the upper and lower shells to the carrier is carried one shell at a time, i.e. first the upper shell is attached and then the lower shell. This is because the inner edges of the upper or lower shell need to be milled in order to match and ensure a consistent space between their facing edges. The shells are fixed to the carrier with their edges presented next to a decorative strip fixture 207 (typically chrome) and so the gap between the upper and lower shells on either side of the fixture must match correctly.

The shape of the shells used in the door arm rests is important because the cross sectional profiles of these components are significantly less deep than for the fascia component of Example 1. Thus the shells must be designed carefully so to resist the forces from shrinkage of the lacquer which might otherwise cause warping of the shape or geometry of the part. This problem is exacerbated by the relatively thin nature of the clam shells of the arm rest which means that flexion is much more likely and so needs to be resisted more carefully.

Thus the invention provides carbon fibre shells that are able to withstand the forces generated during the process of lacquer curing on the surface thereof without significant deformation. Thus the invention is particularly well suited for producing carbon shells and components for inclusion in automobiles that meet specific engineering, design and aesthetic parameters. In particular the invention yields improved methods of producing lacquered carbon shells and the intermediate products required in their production.

Claims

-19 -Claims 1 A carbon fibre shell having an exterior surface, an interior surface and an internal cavity comprising: i) at least one layer of carbon fibre; ii) a bonding material within the matrix of the carbon fibre; and Hi) at least one layer of lacquer applied to all or a portion of the exterior surface.
2 A carbon fibre shell having an exterior surface, an interior surface and an internal cavity comprising: i) at least one layer of carbon fibre; ii) a bonding material within the matrix of the carbon fibre; iii) at least one layer of lacquer applied to all or a portion of the exterior surface; and iv) a flange or skid of carbon fibre material extending around all or a portion of the circumference of the mouth of the internal cavity.
3. A carbon fibre shell according to claim 2, wherein the flange or skirt of material extends around a portion of the circumference of the mouth of the cavity.
4. A carbon fibre shell according to any preceding claim, wherein a multiplicity of layers of lacquer are applied to all or a portion of the exterior surface.
5. A carbon fibre shell according to any preceding claim, wherein the bonding material is a resin, glue or adhesive
6 A carbon fibre shell according to any preceding claim, wherein the interior of the internal cavity is substantially uninterrupted by members or webs of material extending from the shell that extend through the cavity space.
7 A carbon fibre shell according to any preceding claim, wherein the interior of the internal cavity is not interrupted by members or webs extending through the cavity space.-20 -
8. A carbon fibre shell according to any preceding claim, additionally comprising at least one layer of veneer mounted on the exterior surface that covers all or a part of the exterior surface beneath the lacquered area of the exterior surface.
9. A carbon fibre shell according to claim 8, wherein the veneer is a wood veneer
10.A carbon fibre shell according to any preceding claim, wherein the shell additionally comprises apertures through the material of the shell.
11.A carbon fibre shell according to any preceding claim, wherein the shell additionally comprises fixing means attached to the shell for location and attachment of the shell to a further structure.
12.A carbon fibre shell according to claim 11, wherein the further structure is a subassembly of a vehicle.
13. A carbon fibre shell according to claim 12, wherein the vehicle is an automobile.
14.A carbon fibre shell according to either claim 12 of claim 13, wherein the further structure is a component or subassembly of a vehicle dashboard or fascia.
15.A carbon fibre shell according to either claim 12 of claim 13, wherein the further structure is a component or subassembly of a vehicle armrest.
16.A carbon fibre shell according to any of claims 11 to 15, wherein the further structure is produced by 3D printing, preferably the 3D printing medium is 12CF material.
17.A method of manufacturing a carbon fibre shell having an exterior surface, an interior surface and an internal cavity comprising the steps of: i) laying up at least one layer of carbon fibre in the cavity of a female mould wherein the mould comprises a circumferential flange around all or a portion of the mouth of the internal cavity applying bonding material to the carbon fibre layer in the mould; -21 -Hi) applying pressure to the surface of the carbon fibre layer; iv) removing the carbon fibre shell from the mould; and v) lacquering part or all of the external surface of the carbon fibre shell.
18.A method according to claim 17, wherein the method additionally comprises the step of mounting at least one layer of veneer on the exterior surface that covers all or a part of the exterior surface beneath the lacquered area of the exterior surface.
19.A method according to either claim 17 or claim 18, wherein the method additionally comprises the step of removing material from the flange or skirt, preferably by milling.
20. A method according to any of claims 17 to 19, wherein the method additionally comprises making apertures through the material of the product, preferably by milling.
21.A carbon fibre shell manufactured according to the method of any of claims 17 to 20.
22. A product according to any of claims 1 to 16 and 21, or produced according to any of claims 17 to 20, for use in a vehicle, furniture, or part of a building.
23. A product according to claim 22 for use in the interior or cabin of a vehicle.
24. A vehicle comprising a product according to any of claims 1 to 16 and 21 to 23, or a product produced according to any of claims 17 to 20.
25.A vehicle according to claim 24, wherein the vehicle is an automobile, aeroplane or boat, preferably the vehicle is an automobile.