ROOF TILES

Abstract: A process for manufacturing roof tiles includes introducing tile forming material into a hopper (1) for subsequent discharge onto a succession of moving pallets (8) to form a base ribbon (11) which is cut into individual tiles (12). One or more body colouring pigments are added to the material prior to its introduction into the hopper (1), for example in a screw conveyer (2) leading to te hopper, and a secondary colouring pigment or pigments is added to the material in the hopper (1) to provide the tiles with streaked surfaces.

Description: Roof Tiles This invention relates to roof tiles, and relates ' in particular to a process and apparatus for manufacturing a novel type of tile. Roof tiles are generally made of concrete and, in recent years, considerable efforts have been made to manufacture tiles having distinctive profiles and colours such that an improved appearance on a roof may be obtained. Viewed from one aspect the invention provides a process for manufacturing roof tiles comprising introducing tile forming material into a hopper for subsequent discharge onto a succession of moving pallets to form a base ribbon which is compressed and cut into individual tiles, wherein one or more body colouring pigments are added to the material prior to the introduction thereof into the hopper such that the finished tiles are provided with a varying body colour, and wherein one or more secondary colouring pigments are added to the material in the hopper to provide streaks on the tile surface. Thus, roof tiles formed from a process in accordance with this aspect of the invention have a varying body or base colour and a streaked surface and are thus distinctive in appearance. Clearly, the colours of the pigments added to the material both before and after the introduction thereof into the hopper may vary such that a wide range of differently coloured tiles may be formed. For example, red and yellow body colouring pigments may be added alternately to the material before it is introduced into the hopper such that in any batch of tiles the body colour of successive finished tiles -QMP - 2 - varies from red to yellow through shades of orange depending on the mixing in the process. Alternatively, three or more different pigments may be added. A black secondary pigment may be added to the material 5 within the hopper such that black streaks are provided on the tile surface. Alternatively, a number of differently coloured secondary pigments may be introduced into the hopper such that multiple coloured streaks are provided. 10 The manner in which the body colouring pigments are added to the material prior to its introduction to the hopper may vary. The process is preferably such that only limited mixing of the body pigments occurs such that the body colour of any particular 15 tile varies and is not simply a uniform combination of the colours of the pigments. It will be appreciated that the different proposals discussed above whereby the base colours of the tiles may be varied in accordance with the first aspect 20 of the invention are themselves novel and may be advantageous regardless of whether or not the upper surfaces of the tiles are streaked by means of a secondary pigment. Thus the invention extends to the provision of a tile forming process wherein one 25 or more colouring pigments are added to the tile forming material, prior to the introduction of the material into a hopper, such that the finished tiles have a varying base colour. The manner in which the pigments are mixed 30 with the tile forming material affects the body colour variations in the finished tiles. A single pigment added to the material prior to the introduction thereof to the hopper and only partially mixed therewith will result in colour variations of the finished 35 tiles between the colour of that pigment and the natural colour of the tile forming material. Two pigments similarly only partially mixed with the O material outside the hopper will result in colour variations of each tile between the colours of the pigments. It is not however essential for the pigments to be only partially mixed with the tile forming material. For example, batches of material substantially uniformly coloured with different pigments may be introduced into the hopper, and the normal self-mixing of the material occuring in the hopper leads to uneven mixing of the body colours. In this way the predominent base colour of the tiles may vary between two or more colours over a production run. A combination of the above instances i.e. incomplete mixing of each pigment with the material, and self mixing of batches of differently coloured material in the hopper, will result in random colour variations in each tile in addition to gradual variations in the predomiment base colours during a production run. The tile forming material may be supplied to the hopper by means of an elongate rotating screw conveyer which is effective both to mix the tile- forming material and to pass it to the hopper. With such an arrangement, the coloured pigments for the body may be added to the material within the conveyor at an appropriate point along its length such that the required degree of mixing of each pigment occurs. The further along the conveyor the pigment is added, the less mixing there will be with the body material. Different pigments may be added to the material at appropriately spaced intervals in time such that desired colour variations of the finished tiles are achieved. The time intervals may be regularly or randomly spaced. The degree of mixing of each pigment with the material in the conveyor will affect the colour variations in each tile, while the time intervals for which the pigments are added to the material and the degree of self mixing in the hopper may change OMPI the predominent base colour throughout a production run. Alternatively, the tile forming material may be mixed by means of one or more batch mixers, i.e. a large cylindrical pan or suitable container having a mixing element therein, from which it is transmitted either directly or via a suitable conveyor to the hopper. With such an arrangement, one pigment may be added to one batch mixer and a further pigment added to a second batch mixer such that the material in each mixer has a substantially uniform colour, different to that in the other mixer. Material from the two mixers is then introduced into the hopper such that partial mixing occurs either within the hopper itslef or during the conveying of the material to the hopper. Material from each mixer may be passed to the hopper at appropriately spaced time intervals such that desired colour variations of the finished tiles throughout a production run are obtained. Alternatively, the material may be mixed in a single batch mixer in which case a first pigment is added to one batch, a second pigment to the next and so forth, differently coloured material from subsequent batches being partially mixed in either the hopper or on a conveyer. Where it is desired to provide a streaked upper surface, a secondary colouring pigment or pigments may be added to the material within the hopper via supply means which are laterally movable back and forth relative to the hopper such that the position of the streaks on the tiles changes. In a conventional hopper, the means for compressing the tile forming material against the pallets includes a roller rotatable about a lateral axis, and it has been found that by adding the secondary pigment or pigments to the surface of the material at a position above the roller, streaks are formed on the top surface of the tile. OMPI Lateral movement of the secondary pigment supply means above the roller causes variations in the position of the streaks on the upper surface of the tile. Longitudinal displacement of the supply means away from the roller is undesirable since this alters the depth of the streaks and may result in the streaks being formed unnecessarily below the surface of the tile. The method of streaking the surface of the tiles is in itself advantageous, whether or not the body colour is varied and thus viewed from a further aspect the invention provides a process for forming roof tiles comprising introducing tile forming material into a hopper and compressing the material by means of a roller against a succession of longitudinally moving pallets for discharge from the hopper and subsequent cutting into individual tiles, wherein a secondary colouring pigment is added to the material within the hopper by means of laterally movable supply means located above the roller such that streaks of varying position are formed on the upper surface of the tiles. The invention also provides apparatus for manufactur¬ ing roof tiles including a hopper adapated to receive tile forming material, a roller for compressing the material against a succession of longitudinally moving pallets for discharge from the hopper and subsequent severing into individual tiles, colouring pigment supply means located above the roller, and means for effecting lateral movement of the supply means relative to the hopper. Viewed from a further aspect the invention provides apparatus for manufacturing roof tiles comprising a hopper adapted to receive therein tile forming material, means for discharging said material onto a succession of longitudinally moving pallets to form a ribbon, means for compressing the ribbon, and means, for cutting the ribbon into individual tiles ? first colouring pigment supply means adapted to add two or more body colouring pigments to the material prior to the introduction thereof into the hopper, and second colouring pigment supply means for the supply of one or more secondary pigments to the material within the hopper. The second supply means is preferably movable back and forth in a lateral direction relative to the hopper. Viewed from a further aspect the invention provides a roof tile having a streaked upper surface and a varying body colour. An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, wherein: Pig. 1 is a diagrammatic view of apparatus taken in accordance with the invention; and Pig. 2 is a view of part of the apparatus in the direction of arrow II in Figure 1. Referring to Figure 1, tile forming apparatus includes a hopper 1 adapted to receive tile forming material, e.g. concrete mortar, supplied from a feed conveyor 2 via a chute 3. The conveyor 2 includes inlets 4 for dry sand/cement mix and water, and a rotating screw 5 adapted to mix the mortar and urge it towards an outlet 6, disposed above the chute 3. A rotating paddle 7 within the hopper urges the mortar down towards a roller 9 which compresses the material onto a succession of pallets 8. The pallets 8 are linked together and driven rightwardly as shown in Figure 1. The mortar then passes under a slipper 10 which finally compresses the mortar and shapes its upper surface. The mortar emerges as a continuous ribbon 11 which is cut into individual tiles 12 by the blade 13 of the guillotine 14. Thereafter, further handling of the tiles is conventional. - R The feed conveyor includes further inlets 15. located towards its outlet end for the supply of a pigment dispersion or slurry to the mortar within the conveyor. Two or more differently coloured pigments may be introduced to the mortar at regular or random intervals, and the arrangement is such that partial mixing occurs in the downstream end of the conveyor and in the hopper whereby the f nished tiles 12 are provided with a variable base colour. For example, red and yellow pigment dispersions may be introduced to the mortar at respective five and ten second time intervals such that the mortar entering the hopper changes in colour from red through various shades of orange to yellow, and then back through orange to red. The extruded tiles in any batch thus contain a mixture of these colours in varying degrees. Colouring material is also added to the tile forming material within the hopper via tubes 16, and in this way coloured streaks are provided on the upper surface of the ribbon 11. As shown in Fig 2, six supply tubes 16 are mounted, in groups of 3, to rail members 17 extending laterally across the hopper, the tubes being coupled to the rotating arms 17 of a motor 18 whereby the tubes are moved back and forth above the roller and the material within the hopper. In this way, the position of the streaks provided on the upper surface of the ribbon changes. The illustrated arrangement has a capacity for up to six different streaking colours, and the colouring pigments may be pumped to the tubes 16 at regular or random intervals. An alternative arrangement is illustrated in Figure 3, where secondary hoppers 20 are located above the main hopper 1. As shown, the- secondary hoppers are adapted to receive three differently coloured batches of material, which may be prepared one by one in a single batch mixer, or in three separate batch mixers. Material from the secondary hoppers is released inot the main hopper at appropriate time intervals, and self-mixing in the main hopper is such that the body colour of the tiles varies between the colours of the three batches. The combination of a variable body colour and streaks on the upper surface provides a preferred tile made in accordance with the invention with a distinct and attractive appearance. -£ JR " OM

Claims: CLAIMS : 1. /A process for manufacturing roof tiles comprising introducing tile forming material into a hopper for * subsequent discharge onto a succession of moving pallets to form a base ribbon which is compressed * 5 and cut into individual tiles, wherein one or more body colouring pigments are added to the material prior to the introduction thereof into the hopper such that the finished tiles are provided with a varying body colour, and wherein one or more secondary 10 colouring pigments .are added to the material in the hopper to provide streaks on the tile surface. 2. A process as claimed in claim 1 wherein two or more body colouring pigments are added to the material prior to its introduction into the hopper. 15 3. A tile forming process whereinone or more colouring pigments are added, to the tile forming material, prior to the introduction of the material into a hopper, such that the finished tiles have a varying base colour. 20 4. A process as claimed in any of claims 1 to 3 wherein a body colouring pigment or pigments are partially mixed with the tile forming material prior to its introduction into the hopper. 5. A process as claimed in any of claims 1 to 25 3 wherein batches of material which are substantially uniformly coloured with different pigments are introduced into the hopper. 6. A process as claimed in any preceding claim wherein a body colouring pigment or pigments are ^ 30 added to the material in a screw conveyer leading to the hopper. 7. A process as claimed in any preceding claim wherein a body colouring pigment or pigments are added to the material in a batch mixer. OMP 8. A process as claimed in claim 1 wherein the secondary pigment or pigments are added via supply means which are laterally movable back and forth relative to the hopper. 9. A process as claimed in claim 8 wherein said supply means are located above a roller in said hopper arranged to compress the tile forming material against the pallets. 10. A process for forming roof tiles comprising introducing tile forming material into a hopper and compressing the material by means of a roller against a succession of longitudinally moving pallets for discharge from the hopper and subsequent cutting into individual tiles, wherein a secondary colouring pigment is added to the material within the hopper by means of laterally movable supply means located above the roller such that streaks of varying position are formed on the upper surface of the tiles. 11. Apparatus for manufacturing roof tiles including a hopper adapated to receive tile forming material, a roller for compressing the material against a succession of longitudinally moving pallets for discharge from the hopper and subsequent severing into individual tiles, colouring pigment supply means located above the roller, and means for effecting lateral movement of the supply means relative to the hopper. 12. Apparatus for manufacturing roof tiles comprising a hopper adapted to receive therein tile forming material, means for discharging said material onto a succession of longitudinally moving pallets to form a ribbon, means for compressing the ribbon, and means for cutting the ribbon into individual tiles? first colouring pigment supply means adapted to add two or more body colouring pigments to the material prior to the introduction thereof into ^the hopper, and second colouring pigment supply means for the supply of one or more secondary pigments * ξJ . E OM to the material within the hopper, 13. A roof tile having a streaked upper surface and a varying body colour. \

Inventors: BURT PETER, BURT, PETER
Applicants: MARLEY TILE AG, MARLEY TILE A.G.
Application year: 1984
Main classification: B28B13
IPC codes: B28B3, B28B5, B28B13, E04D1