The problem addressed by the present invention relates to the extrusion of material whereby the extruded material has located within it further extruded material which forms a complex design having recognisable images or shapes with the respective substrate materials being visually distinct one from the other such that, for example, the image or shape within the extruded material appears within the article being extruded if these are individual items or else they appear at any cross section if the extruded material-is subsequently contained within a closed can for later processing, received into a portioning machine or else portioned and packaged.

One of the problems experienced with the production of extruded material having recognisable images or shapes located therewithin using presently available apparatus is that it is difficult to produce complex shapes accurately as it can be difficult to avoid an imbalance of extruded material across the face of an aperture or die head which defines the desired shapes and through which the extruded material is produced. This unevenness results in a failure to produce accurate reproduction of required image or shape.

It is an object of the present invention to provide improvements in relation to one or more matters discussed herein or generally.

According to the invention there is provided apparatus for the production of extruded materials having further extruded material located therein, the latter forming recognisable shapes or images. In an embodiment of the invention, the image or shape may comprise a material different from that of the surrounding substrate, such as meat and cheese or else may be the same material but presented in such a manner so as to differentiate therefrom, for example it may be of a different colour or contain material which imparts a different texture.

The apparatus for producing extruded material comprises a hopper which contains the substrate material and at least one further hopper which contains the inner material which will form the shape or image required. The substrate hoppers may also be in the form of refrigeration or freezer units in the case of an ice cream product. The materials contained within the hoppers are fed into a feed chamber by way of connecting pipes. The feed chamber comprises an outer chamber having an inner chamber located therein. The substrate material is fed into the outer chamber and the image material is fed into the inner chamber which is located within the outer chamber such that the two material are maintained separately within the feed chamber. Any number of hoppers or feed chambers can be used depending on the particular application. If the substrates being used are meat, the apparatus may also provided with a moving assy, a fixed assy, including a pulley and a back pressure counter-weight.

A die extrusion unit having a die head which forms'the inner or distinguishing shape required and a discharge aperture is located at the end of the feed chamber. The unit is formed with a number of projections. These projections may be in the form of vanes and serve to

provide support for the region of the extrusion die which forms the internal shape and locate this at the end of the inner chamber or whichever chamber will provide the substrate required to form the distinctive shape. By supporting the die in this manner, this enables the outer substrate to continue to move towards the discharge orifice and past the forming die without contacting the-inner substrate material. In addition, the vanes also serve to direct or channel the outer substrate material as this is caused to move past them. Additional projections may also be provided which serve to restrict the flow of the outer substrate as required as it moves towards the die and onward to the discharge orifice.

The die which determines the shape of the distinguishing image required may, of course, be changed depending on the particular application. The region of the die extrusion unit, the die head itself, which determines the shape of the image located within the extruded material, is divided into a number of separate sections or regions which may be further shaped so as to affect the speed and direction of the movement of substrate material as it passes through the die, as may the region through which the outer substrate passes and may act to restrict or permit movement of same.

In use, the substrate materials to be extruded are caused to move from the respective hoppers towards the die head, along the feed chambers by means of independently controllable pumping machines, said pumping machines enable the feed rates and pressure to be adjusted to suit the volume and nature of material required. It may be desirable to apply different feed rates and pressures to the different materials being used in a particular application.

This would be influenced by how much of a particular material is to be directed to the die.

As the substrate materials move through the feed chambers towards the die and a discharge orifice, the outer substrate and the inner substrate are kept separate. The outer substrate is caused to move along the outer feed chamber and past the region of the die head which forms the inner substrate, during this movement the outer substrate material is caused to contact the vanes and substrate restrictors. These act to interrupt the flow of material and to channel or direct this material towards a particular regions or sections of the die as required, still avoiding contact with the inner substrate material. These regions or sections of the die, when considered individually and as separate from the whole, form a section of the overall shape required, itself being a more simple shape than the whole. Likewise, the movement of the inner substate is directed to the required regions or sections within the die by vanes and substate restictors with the rate of movement of the material restricted as required by contact with substrate restrictors.

It is important that the material is manipulated within the die head to ensure the complete fill of the shape or image and an even extrusion of the material across the whole areas of the shape. By dividing the die into sections or regions and directing a proportion of substrate material into each of the sections, the required manipulation of the material is easier to control. This is because each section can be considered on an individual basis as being a more simple shape and manipulation of material within the more simple shape created by the sectioning of the die is easier to manage.

Manipulation is also achieved by introducing varying degrees of compression to the different materials within the die to overcome the forces of friction generated by the

wetted surface area of the die which would otherwise cause an imbalance of extruded material across the face of the aperture of die. This application of differing degrees of pressure is assisted by the fact that the different materials are retained within separate regions of the feed chamber and can thus be manipulated individually. The flow rate required for the outer substrate may be quite different for that required for the inner substrate.

Once a portion of the material has been directed to and contained within a certain region or section of the die, this facilitates a greater degree of control over the flow of the substrate material. The vanes/substrate restictors of the die in the particular region then act on the substrate, which is still moving under pressure, to restrict or permit movement of this material within the section or region and also to direct the flow within the section so as to ensure an even distribution across the whole of the section or region of the die. As the substrates are forced though the die and out of the output orifice to form the completed extrusion, the simple shapes formed by the sectioning are caused to come together to make the final extrusion having the required complex shape or image located therein.

The substrates are maintained separately as they are caused to move towards the feed plate and are directed towards different regions thereof by virtue of the separate delivery means. As the substrates contact the die extrusion unit the vanes and restictors of the die extrusion unit serve to either interrupt, permit or restrict the onward passage of. the respective substrates through to the output orifice.

Larger shapes are sectioned from the input stage through to the output orifice in order to simplify control of the material and prevent back pressure generated in one area of the shape being transferred to another part of. the shape.

According to the invention there is also provided a method of producing extrudable plastic material having images or shapes located within said material. Said method comprises the steps of providing an inner image or shape forming material or substrate and means of providing an outer periphery forming material or substrate, the step of directing each to particular regions of the same die extrusion unit, the step of providing means for supplying the forming material or substrate, means for forcing the forming material or substrate into the die extrusion unit as required, means for detecting the forcing pressure varying with time and means for changing same in accordance with requirements.

In a further embodiment of the invention there is provided extruded product produced as discussed herein.

In a still further embodiment of the invention there is provided a die for use in respect of the extrusion of material and in particularly the continuous co-extrusion of materials. The die can be made of any suitable material'and by any suitable means including rapid prototyping in which a die is created from a three dimensional drawing by laser scintered equipment which builds up a plastic prototype die very quickly. The die is formed with a number of vanes or the like, the shape and configuration of which will depend on the image or shape to be extruded. The die also formed with one or more substrate restrictors.

It is the aim of the present invention to provide a method apparatus to permit the continuous co-extrusion of two or more extrudable materials to form a complex design with recognisable images or shapes wherein the die provided for forming said complex materials is sectioned to form simpler shapes and the said extruded material is manipulated within the sectioned die with the simple shapes being formed being brought together to form a single more complex shape.

The invention will now be described by way of example and with reference to the accompanying illustrative drawings wherein: Figure 1 shows perspective diagrammatic view of the apparatus for carrying out the present invention; Figure 2 shows a further perspective diagrammatic view of the apparatus for carrying out the present invention; Figure 3 shows a perspective diagrammatic view of the region of the apparatus through which substrate material travels; Figure 4 shows a perspective diagrammatic view of the die extrusion unit; Figure 5 shows a further perspective diagrammatic view of the die extrusion unit with a portion of the outer wall removed; Figure 6 shows a perspective diagrammatic view of the die extrusion unit showing the extrusion die; Figure 7 shows a further perspective diagrammatic view of the die extrusion unit showing the extrusion die and;

Figure 8 shows a product produced by the apparatus of the invention.

Figures 1, 2 and 3 illustrate, diagrammatically apparatus according to the invention. An assy 10 is shown mounted on a support stand 12 and in a substantially vertical attitude. However, depending on the application, the assay may be mounted on a trolley and in a horizontal attitude as shown by Figure 9. Substrate hoppers, not shown, hold the material to be placed within the assy and may be refrigeration or freezer units again depending on the application, for example if material such as ice cream is being used, hold the substate material required, any number of such hoppers can be used depending on the number of substrates needed for a particular application. Feed pipes (not shown) are connected to the hoppers and conduct the substrate material from the hoppers to the assy 10. As shown, separate feeds 14, 16 are provided for the different substrates used. The material which comprises the outer substrate of the product is directed into a feed 16 and the material which is to form then inner substrate which will be used to form the particular shape located within the product is directed to a separate feed 14. The feeds 14,16 lead into separate chambers, a first chamber 18 which receives the outer substrate material and a second or inner chamber 20 which receives the inner substrate. The inner chamber 20 is located within the first chamber 18 such that the two substrates are maintained separately as they pass through the assy 10. Located at the output or discharge end of the assy 10 is a die extrusion unit 22 as shown in Figures 4,5 and 6. The die extrusion unit 22 is received within the first or outer substrate chamber and is secured to the end of the second or inner substrate chamber 20 to form an extension to said chambers.

As shown in Figure 4 the unit 22 formed with a number of projections 24. These projections 24 are in the form of vanes and serve to provide support for that region of the extrusion die which forms the internal shape and also serve to direct or channel the outer substrate material as this is caused to move past them. Further projections 26 are also provided which serve to restrict the flow of the substrate as required as it moves towards the die 28 and onward to a discharge orifice 30. The region of the extrusion die 28 which forms the internal shape required is also formed with projections 32 which act as substrate restrictors to affect the rate and direction of the flow of the second substrate as shown in Figure 5.

In addition to being formed with projections which affect the rate and direction of the flow of the substrates, the extrusion die 28 is divided into regions or sections 34.

Each individual section or region itself forming a shape which is much more simple than the final shape required. The walls of these regions may also be shaped so as to influence the direction and speed of flow of substrate material passing therethrough. The control of the flow of substrate materials through these simpler shaped sections is much easier to effect than through a single section shaped to provide the overall final complex shape required.

As the substrate materials pass through the die 28, a number of different simple shapes are extruded and these different shapes are caused to come together on exiting the die at the discharge orifice 30 such that all the different simple shapes extruded"fit together"to form the complex shape required as shown in Figure 8. It is not until the stage at which the different simple shapes come together that the two substrates which have been extruded come into

contact with each other. The materials are then portioned and/or packaged as required.