The present invention relates to a method for the manufacture of a composite product comprising a core which is preferably foamed or foamable, as well as a top layer material comprising a thermosetting plastic and preferably a fibre reinforcement. The essential manufacturing step consists in shaping the products in a press shape mould.

The invention further relates to a device for carrying out said method.

Background Composite products are used in an increasing variety of applications due to their combination of high strength and low weight. With a suitable choice of materials these products also represent an alternative that is environmentally friendly and where a high degree of recycling is possible. The products are competitive also in other respects, e. g. with respect to degradation under influence of chemicals, heat etc.

A main challenge has until now, been to find a quick and convenient method for the manufacture of such products in order to make them competitive with products of traditional materials, like metals, particularly with respect to price.

Composite products often include several layers of reinforcement in a polymer matrix that typically envelops a foamed core with a very low weight. The reinforcement layers provide strength to the product and may additionally be given a desired surface finish.

Lately a lot of work has been done on laminates based on multiaxial reinforcement of the outer layers, as such layers have a particularly high strength. A multiaxial reinforcement is a reinforcement that comprises several layers of fibre, wherein the fibres of each layer are unidirectional and oriented in a different direction to the fibres of the adjacent layer or layers.

A particular cover layer is often used, for obtaining a particular surface finish for a particular application. In the car industry interior details are often given a fabric or fabric-like surface, e. g. felt, for some components, which give a more exclusive look than a plastic surface, and also provide a sound-deadening effect. Another example is materials that have a smooth, glossy surface and can replace conventional finishing varnish. This is also typical for the car and/or boat industry for external details like wings, door sides, details of the body and the like.

It has not till this date been developed production processes which are convenient for large-scale production of such complex products. This is due partly to the use of

components, like thermoset plastics which require time for setting, and partly to the production tools which are largely oriented for a one-by-one production, which is a relatively time consuming way of production.

The car industry in particular is very cost focussed and it is a matter of great importance for the sub suppliers not only to deliver good-quality products, but also to hold a low price, which presuppose rational manufacturing methods.

The conventional manufacturing method for such structurally complex composite products as mentioned above, includes use of press shape moulds in which the components are placed mainly manually by one or more operators and thereafter pressed or sealed under influence of heat. The press shape mould is generally horizontally oriented. A preheating of one or more of the layers immediately prior to their introduction into the press shape mould is often included. The method is reliable but not efficient for large-scale production.

Some manufacturers have lately tried substituting the conventional thermosetting plastic with thermoplastic that does not require time for curing. Use of thermoplastic is also a basis for this new invention.

Objective It is an objective with the present invention to provide a method for the manufacture of a composite product comprising a core which is preferably foamed or foamable, said method being efficient and labour saving and well suited for large scale production.

It is further an objective to accomplish the aforesaid with simple means and a very high quality and accuracy, in order to meet specified requirements e. g. from the car industry.

Finally it is an objective to provide an entirely new process for the manufacture of such products, in which the manufacturing is generally orientated as a continuous process.

These objectives are accomplished through the method and device according to the present invention.

The invention The invention is characterised by the features defined in the characterising part of claim 1.

Preferred embodiments are disclosed by the dependent claims.

By utilising a process where the top layer or layers has the form of one or more continuous materials or ready, prepared pieces of pre-cut and preconsolidated reinforcement material, a flow of material to the shaping step corresponding to processes of continuous production is obtained. This has not prior to this invention been achieved for the manufacture of products of this type, and this achievement therefore is something quite new in this context. Additionally, as a consequence of the vertical orientation of the materials being fed to the shaping tool, their introduction into the press shape mould tool is assisted by gravity which further contributes to simplifying the process.

By"pieces of pre-cut materials"as used in this context is meant pieces which are wholly or partly cut out of a larger piece of material by the use of a any convenient cutting or dividing operation, e. g. knife, scissors, other mechanical cutting tools, water or heat cutting machinery or other suitable cutting or dividing equipment.

Drawings Fig. 1 is a schematic drawing of a first embodiment of the invention, with a prefabricated foamed core, top layer of felt and the press shape mould tool shown in an open position, Fig. 2 is a schematic drawing of another embodiment of the invention with a prefabricated foamed core, a top layer to the left in a glossy PMMA-film prearranged in the mould, which is shown in open position, Fig. 3 is a schematic drawing of a third embodiment of the invention, where the difference from Fig. 2 consists in that the core is not prefabricated, but is extruded simultaneously with the shaping of the product, Fig. 4 is a schematic drawing of a fourth embodiment of the invention comprising a two- part core, one of which is prefabricated while the other part is extruded simultaneously with the shaping of the product, Fig. 5 is a schematic drawing of the embodiment of Fig. 4, but showing the press shape mould in a closed position, In the first embodiment, cf Fig. l, the foamed core is introduced into the mould individually and fixated with suitable means 11 at a convenient place relative to the press shape mould 2 (2a+2b). It is possible to arrange the press shape mould tool on a movable carriage 3 which is convenient to wheel away from the supply heads 4a, b and 5a, b for the continuous material, whereby the fixation of the core will also be easier. It

Preferred embodiments are disclosed by the dependent claims.

By utilising a process where the top layer or layers has the form of one or more continuous materials or ready, prepared pieces of pre-cut and preconsolidated reinforcement material, a flow of material to the shaping step corresponding to processes of continuous production is obtained. This has not prior to this invention been achieved for the manufacture of products of this type, and this achievement therefore is something quite new in this context. Additionally, as a consequence of the vertical orientation of the materials being fed to the shaping tool, their introduction into the press shape mould tool is assisted by gravity which further contributes to simplifying the process.

By"pieces of pre-cut materials"as used in this context is meant pieces which are wholly or partly cut out of a larger piece of material by the use of a any convenient cutting or dividing operation, e. g. knife, scissors, other mechanical cutting tools, water or heat cutting machinery or other suitable cutting or dividing equipment.

Drawings Fig. 1 is a schematic drawing of a first embodiment of the invention, with a prefabricated foamed core, top layer of felt and the press shape mould tool shown in an open position, Fig. 2 is a schematic drawing of another embodiment of the invention with a prefabricated foamed core, a top layer to the left in a glossy PMMA-film prearranged in the mould, which is shown in open position, Fig. 3 is a schematic drawing of a third embodiment of the invention, where the difference from Fig. 2 consists in that the core is not prefabricated, but is extruded simultaneously with the shaping of the product, Fig. 4 is a schematic drawing of a fourth embodiment of the invention comprising a two- part core, one of which is prefabricated while the other part is extruded simultaneously with the shaping of the product, Fig. 5 is a schematic drawing of the embodiment of Fig. 4, but showing the press shape mould in a closed position, In the first embodiment, cf Fig. l, the foamed core is introduced into the mould individually and fixated with suitable means 11 at a convenient place relative to the press shape mould 2 (2a+2b). It is possible to arrange the press shape mould tool on a movable carriage 3 which is convenient to wheel away from the supply heads 4a, b and 5a, b for the continuous material, whereby the fixation of the core will also be easier. It

is also possible to use two such carriages (not shown) so that the fixation of the core for product No. (n+1) is done while the shaping of product No. (n) takes place. Fig. 1 also shows coils of continuous material, preferably of reinforced thermoplastic 6a, b (the top layer material) and of felt 7a, b respectively, as well as guidings/castors 8a, b and 9a, b respectively for each of these continuous materials. Said continuous materials are referred to with these reference numerals also after having left the coils, e. g. in the position where they are introduced into the press shape mould. The mentioned guidings as well as the supply heads 4,5 may conveniently be arranged on a uniform platform extending over the press shape mould. Fig. 1 also shows two attachment points 13 e. g. in metal, which are arranged partly embedded in the core 1.

Fig. 2 shows an embodiment which deviates from the first one by the feature that instead of a top layer material in felt, a PMMA-film 12 is utilise externally on one side of the product, giving the product the impression of a"varnished"surface. In the illustrated embodiment this is supplied in the form of a prefabricated element with approximately the same form and size as the part of the press shape mould into which it is fitted. It should be noted that in Fig. 2 and the following figures a lot of the reference numerals which would be identical to the ones shown in Fig. 1 are simply left out to make the drawings more surveyable.

Fig. 3 shows a third embodiment of the invention deviating from the second embodiment by the feature that the foam core 1'is extruded and foamed simultaneously with the shaping of the product, and that the core material is supplied to the mould from above by means of an extruder head 10 and a pair of rolls 14. By this embodiment the core is thus cooled subsequent to the sealing of the top layer or layers around the still soft foam core.

Fig. 4 shows still another embodiment of the invention where a two-part core is utilise, of which one part 1 is prefabricated and foamed previously while another part 1'of the core is extruded simultaneously with the shaping as described above with reference to Fig. 3. For this embodiment, the press shape mould is shown also in its closed position, Fig. 5, where the parts 2a, 2b constituting the complete press shape mould have been moved against each other in the directions indicated by the arrows A and B. It will be readily understood that also for the embodiments previously described with reference to the drawings 1-3, the final shaping will take place with a similar closing of the press shape mould as shown in Fig. 5.

Common to all the described embodiments, the top layer or layers which are applied, have the shape of a continuous material until the desired length of these layers have been introduced into the temporarily open press shape mould, partly assisted by gravity. The layers may conveniently be preheated immediately prior to their introduction into the mould in the length and shape which is used for one product, so that the thermoplastic component of the material is fluid or close to fluid when the material enters the mould.

This may be performed by heating means conventional for continuous production processes, like contacting heat, radiation heat etc.

An alternative way of supplying the top layer material is in the form of pre-cut pieces of a preconsolidated reinforcement material, which is also partly aided by gravity when introduced into the press shape mould 2 in a vertical or mainly vertical orientation.

The illustrated embodiments indicate that a continuous material is supplied to the press shape mould from above and downwards by unwinding material from a coil 6 of such material. It is however also within the scope of the invention to let a suitable length of pre-cut top layer material, possibly preconsolidated reinforcement material, be fed vertically to a position outside the press shape mould 2, and thereafter bringing it into the mould by a horizontal motion of either the material 6 itself or of the carriage 3 onto which the mould is arranged. Also for such an embodiment gravity will assist the introduction of the material, by holding it in a position rendering it unnecessary to manually adjust its position after the horizontal motion has been made.

As it will be understood from the indications above, significant time and labour savings are achieved with this continuous type, vertically oriented process, which enables final products to be manufactured with required surface finish and necessary fittings in one operation only. This is an improvement that for large-scale production will have a decisive influence with respect to the ability to manufacture products at a cost that the market will accept.

Examples of products suitable for such production are interior and exterior details of cars, like seat backs, door sides, details of the front and/or rear (bumpers etc.), and other products requiring lightweight and strong/shock absorbing components. For many products it will be desirable or required to include reinforcements, eyes, attachments for bolts or attachments for headrests on car seats. This may readily be combined with the method according to the invention e. g. by embedding suitable attachments in the core material being fixated in the mould, possibly in addition to"dummy-extenders"that

hold the pieces on their correct places and may be reused after completed shaping, and also serves the purpose of avoiding inflow of polymer into openings/attachments equipment which need to be maintained clean.

The top layer material will generally by itself be a composite of a thermoplastic and a reinforcement, which have priorly been shaped to a homogenous continuous material with dimensions and properties adapted for one or several products.

For products not requiring great strength the top layer material may be a thermoplastic without reinforcement. We still use the description composite product with regard to the final product as, under any circumstances, it will include a core which is physically and/ or chemically different from the top layer material.

In order to obtain a best possible environmental benefit, it is often convenient to use the same polymer for the core as for the matrix of the top layer material, but this is not an essential requirement for the invention.

The core will under most circumstances consist of or comprise a polymer material which is foamed in advance or which is foamed during the manufacturing process according to the invention. For special purposes cores of other materials may be used, e. g. if it is necessary for a core to have a higher degree of temperature resistance.

Regarding the reinforcement, that in itself is optional, it may be of any convenient nature for such products. It is particularly preferred with respect to the properties of the final product, to use so called multiaxial knitted or woven reinforcements, where there are long, continuous fibres in several layers, each layer with a directional orientation of the fibres that differs from the orientation of the fibres in the adjacent layers to both sides and which therefor provides a very high tensional strength for the reinforcement and also for the final product.

Freedom of choice with respect to material combinations gives the possibility of products with a very high ability to absorb energy, which is a requirement for being accepted for e. g. exterior details for the car industry. This advantage is however common for all products of this type, irrespective of their manufacturing method.

hold the pieces on their correct places and may be reused after completed shaping, and also serves the purpose of avoiding inflow of polymer into openings/attachments equipment which need to be maintained clean.

The top layer material will generally by itself be a composite of a thermoplastic and a reinforcement, which have priorly been shaped to a homogenous continuous material with dimensions and properties adapted for one or several products.

For products not requiring great strength the top layer material may be a thermoplastic without reinforcement. We still use the description composite product with regard to the final product as, under any circumstances, it will include a core which is physically and/ or chemically different from the top layer material.

In order to obtain a best possible environmental benefit, it is often convenient to use the same polymer for the core as for the matrix of the top layer material, but this is not an essential requirement for the invention.

The core will under most circumstances consist of or comprise a polymer material which is foamed in advance or which is foamed during the manufacturing process according to the invention. For special purposes cores of other materials may be used, e. g. if it is necessary for a core to have a higher degree of temperature resistance.

Regarding the reinforcement, that in itself is optional, it may be of any convenient nature for such products. It is particularly preferred with respect to the properties of the final product, to use so called multiaxial knitted or woven reinforcements, where there are long, continuous fibres in several layers, each layer with a directional orientation of the fibres that differs from the orientation of the fibres in the adjacent layers to both sides and which therefor provides a very high tensional strength for the reinforcement and also for the final product.

Freedom of choice with respect to material combinations gives the possibility of products with a very high ability to absorb energy, which is a requirement for being accepted for e. g. exterior details for the car industry. This advantage is however common for all products of this type, irrespective of their manufacturing method.