EP0148886B1

EP0148886B1 - Roof tiles

Info

Publication number: EP0148886B1
Application number: EP84902528A
Authority: EP
Inventors: Peter Burt
Original assignee: Marley Tile AG
Current assignee: Marley Tile AG
Priority date: 1983-06-21
Filing date: 1984-06-21
Publication date: 1987-11-19
Also published as: DK76685A; EP0148886A1; ZA844712B; FI81994C; JPS60501599A; DK153597B; DE3467525D1; WO1985000135A1; FI850648A0; FI850648L; FI81994B; DK153597C; GB8316833D0; BR8406933A; CA1245039A; DK76685D0

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

This invention relates to a process 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.
In GB-A-1577321 there is disclosed a process for manufacturing concrete roof tiles in which a coloured pigment is added to a quantity of main tile body forming mortar and mixed therewith, the quantity of mortar is introduced into a hopper, a secondary material is added to said quantity of mortar in the hopper, said secondary material comprising a second coloured pigment whose colour is different to that of the first coloured pigment, the quantity of mortar and the secondary material are partially mixed in the hopper so as to provide a mass of mortar with a variegated colour including substantial areas whose colour is determined predominantly by the first pigment and areas whose colour is determined predominantly by the second pigment, and the mass of mortar is extruded onto a succession of moving pallets to form a base ribbon which is compressed and cut into individual tiles, the tiles having a variegated colour.
In this process disclosed in GB-A-1577321, the secondary material is a small quantity of pigmented slurry which is introduced in such a way as to produce distinct streaks only in an upper region of the tile. The body colour of the tile remains constant.
The present invention is characterised in that said secondary material is a second quantity of main, body-forming mortar, said second coloured pigment being added to said second quantity of mortar and at least partially mixed therewith prior to introduction into the hopper, and the arrangement being such that throughout the mass of mortar which is extruded to form the tiles there are, in addition to the substantial areas whose colour is determined predominantly by the first pigment, substantial areas whose colour is determined predominantly by the second pigment and substantial areas whose colour is determined by a mixture of the first and second pigments, so that the tiles have a corresponding variegated body colour.
Thus, as opposed to producing distinct surface streaks, these steps in accordance with the invention produce a varying body colour. The colours of the pigments added to the material 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 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.
The manner in which the body colouring pigments are added to the material prior to its introduction to the hopper may vary. The process should be such that only limited mixing of the body pigments occurs such that the body colour of any particular tiles varies and is not simply a uniform combination of the colours of the pigments.
The manner in which the pigments are mixed 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 tiles between the colour of that pigment and the natural colour of the tile forming material. In a process in accordance with the invention, two pigments similarly only partially mixed with the 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 predominant 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 predominant 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 the predominant 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 itself 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.
In addition to providing the variegated body colour, it may be desired to provide surface streaks, by adding a surface colouring pigment or pigments to the material within the hopper. A black secondary pigment may be added to the material 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. The addition may be 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. 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.
An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, wherein:

Fig. 1 is a diagrammatic view of apparatus for carrying out the process in accordance with the invention; and
Fig. 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.
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 finished 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 27 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 into 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 the tile of the preferred embodiment with a distinct and attractive appearance.

Claims

1. A process for manufacturing concrete roof tiles (12), in which a coloured pigment is added to a quantity of main tile body forming mortar and mixed therewith, the quantity of mortar is introduced into a hopper (1), a secondary material is added to said quantity of mortar in the hopper, said secondary material comprising a second coloured pigment whose colour is different to that of the first coloured pigment, the quantity of mortar and the secondary material are partially mixed in the hopper so as to provide a mass of mortar with a variegated colour including substantial areas whose colour is determined predominantly by the first pigment and areas whose colour is determined predominantly by the second pigment, and the mass of mortar is extruded onto a succession of moving pallets (8) to form a base ribbon (11) which is compressed and cut into individual tiles (12), the tiles having a variegated colour, characterised in that said secondary material is a second quantity of main, body-forming mortar, said second coloured pigment being added to said second quantity of mortar and at least partially mixed therewith prior to introduction into the hopper (1), and the arrangement being such that throughout the mass of mortar which is extruded to form the tiles (12), there are, in addition to the substantial areas whose colour is determined predominantly by the first pigment, substantial areas whose colour is determined predominantly by the second pigment and substantial areas whose colour is determined by a mixture of the first and second pigments, so that the tiles have a corresponding variegated body colour.

2. A process as claimed in claim 1, characterised in that a flow of mortar is provided to the hopper (1) and the first and second pigments are supplied to the flow at intervals so that, in the flow supplied to the hopper (1), there are quantities of mortar which are coloured predominantly by the first pigment and quantities which are coloured predominantly by the second pigment.

3. A process as claimed in claim 2 characterised in that the first and second pigments are introduced such that there is incomplete mixing with their respective quantities of mortar before passing into the hopper (1).

4. A process as claimed in claim 3 characterised in that the flow of mortar is caused by a screw feed conveyor (5) and the pigments are introduced into the mortar at positions (15) towards the outlet (6) of the conveyor.

5. A process as claimed in claim 1, characterised in that the first and second pigments are pre-mixed with their respective quantities of mortar and arranged in batches (20) which are introduced at intervals into the hopper (1).

6. A process as claimed in any preceding claim characterised in that at least one further, different coloured pigment is introduced into the mortar in the same manner as said second pigment.

7. A process as claimed in any preceding claim characterised in that a surface colouring pigment is introduced into the hopper (1) in such a way as to provide streaks of colour on the upper surfaces of the tiles (12) in addition to the variegated body colour provided by the other pigments.

8. A process as claimed in claim 7 characterised in that the surface colouring pgiment is added by supply means (16) terminating above the level of mortar in the hopper (1).

9. A process as claimed in claim 8 characterised in that there is a roller (9) in the hopper (1) arranged to compress the mortar against the pallets (8) and the supply means (16) are positioned over the roller (9).

10. A process as claimed in claim 8 or 9, characterised in that the supply means (16) are moved laterally back and forth relative to the hopper (1).