GB2190871A

GB2190871A - Concrete tiles

Info

Publication number: GB2190871A
Application number: GB08613010A
Authority: GB
Inventors: Leslie Gerald Hammond
Original assignee: Anchor Building Products Ltd
Current assignee: Anchor Building Products Ltd
Priority date: 1986-05-29
Filing date: 1986-05-29
Publication date: 1987-12-02
Also published as: GB2190871B; GB8613010D0

Abstract

Extruded concrete tiles having a changed appearance of that surface of the tiles which is uppermost in use are produced from a cementitious mixture in which a colorant having a different colour to that of the cementitious mixture is applied through at least one aperture which is moved transversely to the direction of tile extrusion. The aperture may be defined by a slot in a tubular member cooperating with a colorant receiving groove in a rod member extending through the tubular member with one member being rotatable relative to the other; or the aperture may be a feed member which is reciprocated across the direction of tile extrusion. The colorant may be introduced into the cementitious mixture in the feed box or may be applied to the extruded ribbon of tiles.

Description

SPECIFICATION Concrete tiles The present invention relates to extruded concrete tiles of which that surface which is uppermost in use is provided with an appearance which has been changed by the application of a colorant having a different colourto that of the tile proper body colour, for example to produce a tiled structure, such as a roof, which has a simulated weathered or stone-like appearance.

Apparatus for producing extruded concrete roofing tiles have been known for over 40 years and include a hopper-like box which is disposed above a conveyor path and which is charged with a cementitious mixture including sand and cement, the cementitious mixture being continuously stirred by means of a rotating paddle disposed within the box. A succession of pallets for moulding the undersurfaceofthetiles is driven along theconveyor path and beneath the box so that the cementitious mixture forms on the pallets and is compressed therein by means of a rotating roller disposed within the box downstream ofthe paddle and having a flat or contourwhich corresponds to the upper surface ofthe tile to be formed.The cementitious mixture is further compressed on the pallets as they pass out of the box by means of a slipperwhich is disposed downstream oftherollerand also hasaflator contourwhich corresponds to that of the upper surface ofthetile,to form acontinuous ribbon of cementitious mixture on the pallets. The ribbon is subsequently cut into tile forming lengths downstream ofthe box by means of a suitable cutting knife and the pallets with the wet formed tiles thereon are conveyed to a curing location.

For many years it has been known to provide extruded concrete roof tiles with a streaky surface appearance to produce a simulated effect, by introducing a colorant in a continuous or random manner into the cementitious mixture within the box, in that area of the box where the cementitious mixture therein will form the upper surface region of the tiles. Indeed, one of the first methods employed was for a worker to stand beside the box and sprinkle, e.g. with a shovel, charges of colorant in the form of a powder into the cementitious mixture in the box. But th is method never did provide a consistent streaky appearance and was expensive in colorant, time and operating personnel.

Accordingly, more reliable automated methods were developed.

In a more recent known method, colorant in the form of a water/pigment mixture is fed into the cementitious mixture through a flexible hose which extends through a rigid metal pipe and projects only a short distance from the end of the pipe so as to touch the periphery of the roller. Because of the surge of cementitious mixture around the periphery of the roller due to roller rotation, the projecting portion ofthe rubber hose is randomly deflected to a sufficient extent to cut-off theflow of colorant so that the colorant is introudced into the cementitious mixture at randomlytimed intervals.

In another known method, which is disclosed in U.K. Patent Specification No. 1577321, colorant in theform of a cement slurry is introduced into the cementitious mixture in the box through one or more pipes of which the or each outlet is disposed either a short distance upstream of the paddle or between the paddle and the roller. By means of valves operated bya random signal generator, the colorant is introduced into the cementitious mixture at randomlytimed intervals.

In a further known method colorant in the form of an acrylic paint is fed continuously into the cementitious mixture through a pipe or pipes terminating at a short distance either abovethe roller or upstream ofthe paddle. The colorant is stored in a suitable container which in one case is a pressure vessel to which compressed air is supplied to feed the colorant to the cementitious mixture orthe container is connected to a continuously operating pump which is switched on and off with the extrusion apparatus.

All the automated methods described above have the disadvantage that the outlets of the pipes can easily be blocked by the cementitious mixture resulting in some tiles being without a streaky appearance, and others having too much colorant thereon due to sudden surges in supply. Thus, it is necessary to stop the extrusion machineto remove the blockages etc., resulting in the expense of down time. Moreover, as the level of cementitious mixture decreases, the pipes are subject to vibrations from the machine operation and from the successive new charges of cementitious mixture resulting in unacceptable increase in the amount of colorant on the tile surface.

Another disadvantage of the known methods, in particularwith regard to some types of contoured roof tiles is that a roof made with such tiles looks different when the roof is viewed from different angles. Thuswith say red tiles having blackstreaks the roof can look all red when looked at one way, all blackwhen looked at anotherway and have a candy stripe appearance when looked at from yet another way.

Accordingly, the main objectofthe present invention isto provide a concrete tile having a changed uppersurfaceappearanceinwhichthe aforesaid disadvantages are minimized or avoided.

To this end and from one aspect, the present invention consists in a method of producing extruded concrete tiles from a cementitious mixture, in which a colorant having a different colourtothat of the cementitious mixture is applied in such mannerastochangetheappearanceofthatsurface ofthe tiles which is uppermost in use, characterized inthatthe colorant is applied through at least one aperture which moves transversely of the direction oftile extrusion.

From another aspect, the present invention consists in apparatus for producing extruded concrete tiles from a cementitious mixture in which a colorant having a different colourto that ofthe cementitious mixture is applied in such manner asto provide a changed appearance of that surface ofthe tiles which is uppermost in use, characterized by means defining at least one aperture for applying the colorant and means for causing the at least one aperture to move transversely ofthe direction of tile extrusion.

Byapplyingthecolorantthroughatleastone aperture which can be moved transversely of the direction oftile extrusion not only is an improved and more consistent changed surface appearance obtained with all types oftiles but the unacceptable differences in surface appearance hitherto experienced in some types of contoured tiled roofs when viewed from different angles are substantially avoided, the extrusion apparatus is subject to less down time and the colorant flow rate and location of colorant may be infinitely varied to provide infinite acceptable variations in the changed surface appearance.

Thecolorantmaybeappliedthroughtheaperture into the cementitious mixture in the box, orto the extruded ribbon ortiles, downstream of the box continuously, intermittently or at randomly timed intervals.

In the continuous mode a pump is connected in the supply line between a containerforthecolorantand the aperture and the pump is switched on or off when the tile extrusion apparatus is switched on or off. Alternatively,the colorant may be a pressure vessel to which compressed air is supplied to feed the colorant to the aperture.

In the intermittent or random mode, a suitable pump can be used as the feeding means and avalve which is adapted te be opened and closed at randomly timed intervals, is disposed in the colorant supply line between the pump and the aperture.

In a preferred embodiment of the invention, the means defining the aperture may be a slot in a tubular member co-operating with a colorant receiving groove in a rod member extending through the tubular member with one of said members being rotatable relative to the other of said members, so that the aperture moves continuously along thetubular memberfrom one end to the other and then from that one end to the other end and so on.

The groove may be of helical shape and the slot straight orthe groove may be straight and the slot helical. The helical groove or slot, as the case may be, mayextendthrough at least one turn and have an axial extent which is the same or substantially the same as the width of the particular tile being extruded.

In another embodiment the aperture may be reciprocated i.e. moved back and forth, across the direction oftile extrusion e.g. by means of a suitable drive such as motor or piston and cylinder device.

More than one feed aperture may be provided so that different coloured colorants may be applied at the same time.

In the case where the colorant is introduced into the cementitious mixture in the box, the tubular member may be supported between opposite sides of the box or alternatively or in addition thetubular member may be constituted bythe paddle shaft so that the colorant is fed into the paddle shaft as disclosed in the specification of ourcopending patent application No. 8603287.

The invention also consists in a concrete tile having a changed surface appearance, which is preferably produced by applying the colorant through a moving aperture.

In orderthatthe invention may be readily understood, reference will now be made, by way of example, to the accompanying drawings,inwhich:- Figure lisa diagrammatic side elevation of an apparatus for making extruded concrete roofing tiles having a changed surface appearance, Figure2 is a plan view of the apparatus of Figure 1, Figure 3 is a front elevation to a larger scale of part ofthe apparatus of Figure 1, Figure 4 is a detail view of a rod memberforming part ofthe apparatus of Figure 1, Figures a detail view of another embodiment of rod member, Figure 6 is a partial plan view of another embodiment, Figures 7a to 7c, are illustrations ofvarying colorantflows produced during operation ofthe apparatusofFigures1 and 2, and Figure 8 is a plan view of a contoured concrete roof tile having a changed surface appearance and produced by the apparatus of Figure 1.

Referring to Figures 1 and 2 of the drawings, the tile extrusion apparatus comprises, as is known, a conveyor path 1 along which pallets 2 for forming the undersurface ofthe tiles are moved in end to end abutment by the main machine drive which is generally indicated at3. The pallets are moved along a stationary track 4 of the conveyor path 1 underneath the extrusion head 5 to be described.

Acementitious mixture 6 including sand, cement and a colouring pigment, for providing through colourtiles, is produced in a mixer (not shown) and isfed bya mixconveyor7intoa hopper-likebox8 forming part of the extrusion head 5. A stirring paddle 9 is provided in that area ofthe box 8 where the cementitious mixture will form the upper surface region ofthetiles in orderto keep the mixture moving in that area. The paddle 9 has a driven shaft 10 mounted in suitable bearings, not shown, in oppositely facing side walls ofthe box and a plurality of paddle pins 11 fixed to and projecting radially from the shaft 10. Just downstream ofthe paddle 9 is a compression roller 12followed by a slipper 13, both of which have a contoured periphery which corresponds to, and forms, the upper surface ofthe tiles, in this case contoured roof tiles.

As each pallet 2 is moved beneath the extrusion head 5, it receives a charge of cementitious mixture from the upstream end ofthe box 8, which charge forms the undersurface and middle regions ofthe tile, and then a charge from that area of the box where the paddle 9 is situated to form the upper surface region ofthetile. The rotating roller 12 compresses the cementitious mixture on the pallet 2 to form the uppersurface contourand isfurther compressed by the slipper 13 as that pallet 2 passes out from underneath the extrusion head 5. Thus, there informed on the pallets 2 a continuous, extruded contoured ribbon 14 of cementitious mixture which is cut into tile forming lengths 15 by a reciprocating cutting knife 16.The severed tiles 15 on their respective pallets 2 are moved away from the extrusion head 5 and along the conveyor path 1 by a take-off conveyor 17 (only part shown) whence they are conveyed to a curing location.

In the known tile making apparatus illustrated in Figures 1 and 2, provision is made for the concrete roofing tiles to have a changed surface appearance, to which end, means is provided for applying a colorant having a different colourto that ofthe cementitious mixture which, in this embodiment, is introduced into the cementitious mixture 6 in the box 7, a tubular member 30 which in this embodiment is closed at one end is provided and a circular in cross-section rod member, driven by a suitable motor32,projectsintothetubularmemberthrough its other end with the periphery of the rod member 31 rotatably engaging with the inner surface of the tubular member 30.Referring now to Figures 3 and 4, the tubular member30 is provided with an axial slot 33 which faces generally downwardly in this embodimentandwhich extends wholly or partially acrossthewidth ofthe particulartiles being formed, forexamplethecontoured rooftile illustrated in Figure 5. One end of a colorant supply pipe 18 is fixed to the tubular member 30 outside the box 8 and leads into a radial passage 34through the wall ofthe tubular member. The other end ofthe pipe 18 is connected to a monopump 19 which is, in turn, connected buy a pipe 20 to a container 21 containing a colorant22ofa differentcolourtothatofthe cementitious mixture 6.

In orderto feed the flow ofcolorant into the cementitious mixture 6 in the box 8, the rod member 31 is provided with a circumferentially extending annularfeed groove 35 which is in alignment and in communication with the passage 34 and a helical groove 36 in communication with the feed groove 35a. The helical groove 35a extends for approximately one turn and terminates ator adjacent the far end of the slot 33. The cooperation of the groove 36 with the slot 33 provides a feed aperture 37 through which the colorant 22 is introduced into the mixture 6 in the box. The motor 32 may be a a variable speed electric motorwhich could be reversible and which is connected to the rod member 31 through any suitable means such as a coupling 38.

The colorant 22 in this instance is a suitable acrylic paint which is compatible with, and of a less viscous consistency than that of, the cementitious mixture.

By way of example Applicants have found that a suitable simulated weathered appearance is provided to a tiled roof if the cementitious mixture is red and the colorant is black. The pump 19 is ofthe continuously operating kind which is switched on and off with the tile making apparatus so that the colorant is continuously delivered bythe pump 19 through pipe 18, passage 34, annular groove 35, feed groove 35a into the helical groove 36 and out through the feed aperture 37.However, during operation ofthe apparatus, the feed aperture 37 is not static as the rod member 31 is being rotated by the motor32. This has the effect of causing the aperture 37 to move transversely of the direction of tile extrusion, i.e. the aperture 37 always moves continuously in one direction e.g. from the left hand end 15 to the right hand always and of the slot 33 as indicated by the arrow 38. Because ofthe configuration ofthe groove and slot arrangement when the aperture reaches the right hand end of the slot 33, it disappears as it were, and reappears at the left hand end of the slot orwhen the aperture starts to disappearatthe right hand slot wend it starts to reappear at the left hand slot end.Alternatively, when the aperture 37 reaches the right hand end of slot 33, the direction of rotation ofthe motor is reversed and the aperture moves from right to left then reciprocallytraversing the direction oftile extrusion. Thus, the black paint 22 is injected continuously into the red cementitious mixture 6 through the feed aperture 37 to change the surface appearance ofthe tiles 15 e.g. as illustrated in Figure 8. In orderto vary the changes in the surface appearance, it is possibleto vary any one or more of thefollowing, namely; the speed of movement of the or each colorant feed aperture, the speed of tile extrusion and the amount of injected colorant.

In the modification of Figure 5, the rod member 31 a has a helical feed groove 36a which extends over more than one turn.

Referring to Figure 6, this shows a double acting piston and cylinder device 40 of which the piston 41 is fixed to a feed member 42 provided with feed passages 43 and 44forterminating in respective feed apertures 45 and 46. Different coloured colorants are fed through the pipes 18 to flexible pipes 18a connected to the respective passages 43 and 44.

Operation ofthe device 40 causes the feed member 42andthustheapertures45and46toreciprocate transversely ofthe direction of tile extrusion and feed the colorants into the cementitious mixture 6.

The left hand supply pipe 18 is connected to colorant supply means like those forthe right hand supply pipe 18.

Instead of two feed apertures or if it is decided to feed only one colour, only one aperture 45 or46 may be provided or used respectively.

Instead of being driven by the device 40, the feed member 42 may be driven by a rack and pinion mechanism.

It should be appreciated that the tile illustrated in Figure 8 shows just one changed surface appearance; generally speaking the surface appearances of say 100 tiles will be different although repeat surface appearances may also be obtained.

Whilst a particular embodiment has been described, various modifications may be made without departing from the scope ofthe invention.

For example, the changed surface appearance can be provided on,flat, plain and cladding tiles and different colour combinations can be used otherthan that described.

In addition tothe colorantfeed arrangement already described, the paddle 9 may be provided with a hollow shaft as disclosed i n the specification ofourco-pending U.K. PatentApplication No.

8603287, the subject matter of which is incorporated into this specification by inference. The colorant supplied to the paddle may be eitherthe same ora different colourto that supplied tothetubular member 30.

However, preferably,the rotating hollow shaft 9 of the paddle is provided with at least one helical slot likethe groove 36 and a stationary rod member like the rod member 31 projects into the shaft and is provided with an axial groove, like the axial slot 33, facing in the downward direction. The cooperation of the helical slot in the rotating paddle shaft 9 with the stationary axial groove in the rod member to which the colorant is fed provides the feed aperture. The speed of the paddle can be varied as desired.

In another embodiment, the colorant feed arrangement illustrated in Figures 3 or 4 cou Id be modified in a similar mannerto that described forthe paddle shaft in which case the motor 32 would drive thetubularmember30whichwould have a helical slot and the roof member31 would be stationary and have an axial groove.

In a still furtherembodiment,the rod member could be provided with at least one other colorant feed groove which cooperates with the same or anotherslot in the tubular member or paddle shaft as the case may be and different or the same coloured colorants fed to the different feed grooves.

Any ofthe colorant feed arrangements herein described except for that concerning the paddle shaft could be disposed outside and downstream of the box, and located so as to provide a flow of colorant from the feed aperture directly onto the extruded ribbon 14 ortiles 15. Moreover, further variations in the surface appearance can be obtained by the use of an air knife which extendstransversely ofthe direction of tire extrusion above the extrusion path, and directs a large volume of air through a slot in a manifold onto the surface ofthe extruded ribbon 14 tiles 15. The manifold is connected by a suitable passage to a chamber in which a motor driven fan producestherequisitevolumeofairflow.

Claims

1. A method of producing extruded concrete tiles from a cementitious mixture, in which a colorant having a different colourto that of the cementitious mixture is applied in such manner as to change the appearance of that surface ofthe tiles which is uppermost in use, characterised in that the colorant is applied through at least one aperture which moves transversely of the direction of tile extrusion.

2. Apparatus for producing extruded concrete tiles from a cementitious mixture in which a colorant having a different colourto that ofthe cementitious mixture is applied in such manner as to provide a changed appearance of that surface of the tiles which is uppermost in use, characterised by means defining at least one aperture for applying the colorant and means for causing the at least one apertureto move transversely ofthe direction oftile extrusion.

3. Apparatus as claimed in claim 2, wherein the means defining the aperture is a slot in a tubular member co-operating with a colorant receiving groove in a rod member extending through the tubular memberwith one of said members being rotatable relative to the other of said membersso that the aperture moves continuously along the tubular member.

4. Apparatus as claimed in claim3,whereinthe groove is of helical shape and the slotstraight.

5. Apparatus as claimed in claim 3, wherein the groove is straight and the slot is of helical shape.

6. Apparatus as claimed in claim 4 or 5, wherein the helical groove or slot, as the case may be, extendsthrough atleastoneturn and has an axial extent which is the same or substantially the same as the width ofthe particular tile being extruded.

7. Apparatus as claimed in claim 2, wherein the means defining the aperture is a feed memberwhich is reciprocated across the direction of tile extrusion.

8. Apparatusasclaimed in claim7,whereinthe feed member has at least one further feed aperture so that different coloured colorants may be applied through the apertures at the same time.

9. Apparatus as claimed in any one of claims 2 to 6, wherein the rod member is provided with at least one other colorant feed groove which co-operates with the same or another slot in the tubular member to enable different coloured colorants to be fed to the different feed grooves.

10. Apparatus as claimed in any one of claims 2 to 6 and 9, wherein the colorant is introduced into the cementitious mixture in a hopper-like box and wherein the tubular member is supported between opposite sides of the box.

11. Apparatus as claimed in claim 10, wherein the cementitious mixture is stirred in the box by means of a paddle mounted on a shaft and wherein the tubular member is constituted by the paddle shaft.

12. Apparatus as claimed in any one of claims 2 to 8, wherein the means defining the feed aperture is located outside a hopper-like box in which the cementitious mixture is contained so as to provide a flow of colorant from the feed aperture directly onto an extruded ribbon ortiles.

13. Apparatus as claimed in any one of claims 2 to 12,and further comprising an airknifewhich extends transversely of the direction of tile extrusion above the extreme path for directing a large volume ofairthrough a slot in a manifold onto the surface of the extruded ribbon ortilesto providefurther changes in the surface appearance ofthe upper surfaces of the tiles.

14. A method of producing extruded concrete tiles from a cementitious mixture substantially as herein before described with reference to the accompanying drawings.

15. Apparatus for producing extruded concrete tiles from a cementitious mixture substantially as hereinbefore described with reference to Figures 1 to 4 of the accompanying drawings.

16. Apparatus for producing extruded concrete tiles from a cementitious mixture substantially as herein before described with reference to Figures 1 and 2 as modified by Figure 5 of the accompanying drawings.

17. Apparatus for producing extruded concrete tiles from a cementitious mixture substantially as herein before described with reference to Figures 1 and 2 as modified by Fig u re 6 of the accompanying drawings.

18. Aconcretetilehaving achangedsurface appearance whenever made by the method of claim 1 orthe apparatus as claimed in any one of claims2 to 18.

19. A concrete tile having a changed surface appearance whenever made by the method of claim 1 orthe apparatus as claimed in any one of claims 2 to 18 and substantially as herein before described with reference to Figure 8 ofthe accompanying drawings.