GB1560831A - Manufacture of tiles slabs bricks blocks and like articles - Google Patents

Description

(54) IMPROVEMENTS IN OR RELATING TO THE MANUFACTURE OF TILES, SLABS, BRICKS, BLOCKS AND LIKE ARTICLES (71) We, REDLAND ROOF TILES LIMITED, a British Company, of Redland House, Castle Gate, Reigate, Surrey, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be patricularly described in and by the following statement: This invention relates to the manufacture of tiles, slabs, bricks, blocks and other like articles.

It is known to manufacture tiles, for example roofing tiles and other tiles for use as external cladding of buildings, by feeding base material into a hopper mounted above a continuously moving conveyor carrying a succession of pallets, the hopper defining a slit-like opening through which the base material is discharged onto each pallet in turn to form a ribbon of the base material thereon, the ribbon being subsequently cut transversely to form individual tiles.

Such a process may also be used for the manufacture of other articles such as floor tiles, concrete slabs, bricks and blocks.

Tiles produced from base material in this manner hereinbefore defined may of course provide the finished product when subsequently cured. This is the case where the base material has admixed therewith a colouring agent, i.e. a suitable pigment thus to provide a coloured tile, or indeed any of the other aforesaid products.

However, one form of tile is produced as aforesaid from a base material which has no colouring agent admixed therewith. In order to obtain a coloured tile it has been the practice to sprinkle coloured granules onto a slurry-coated upper surface of freshly moulded tiles. Sprinkling of the granules onto the upper surface of the tiles has been effected with good results using a gated hopper, the granules passing through an aperture in the hopper whereby an even flow of granules onto the slurry coated upper surface of the tiles is achieved.

The slurry coating for application to the upper surface of the tiles may be made up from cement, water and pigment, the cement water ratio being chosen to give a slurry of suitable viscosity, or, the slurry may comprise sand, water and pigment also of suitable viscosity.

Granules applied to slurry coated tiles, as aforesaid, may be of one colour, e.g. red, or, where a mottled or speckled finish is required, granules of more than one colour may conveniently be applied from one or more gated hoppers. Gated hoppers of the type used hitherto usually comprise a reciprocal box-like member with suitable openings provided in an underside thereof through which the granules are caused to pass. When more than one colour of granule is used, extra hoppers are employed.

For tile production plant operating at up to 60 tiles per minute this form of equipment has proven most adequate. However, in high speed production plant, i.e. at speeds in excess of 60 tiles per minute and as high as 120 to 150 tiles per minute, gated hoppers of the type used hitherto suffer from mechanical breakdown to such a deeree that their use is uneconomical.

With the need to produce a tile having a "streaky" finish rather than a mottled finish this difficulty has become more pronounced.

The invention provides a granule applicator comprising hopper means for storing granules, and automatic means for continuously controlling the flow of granules from the hopper means randomly. Thereby different tiles or similar articles moving past the hopper means may receive different amounts or arrangements of granules.

The invention further provides a granule applicator comprising hopper means for storing granules, means to feed a succession of tiles or similar articles past the hopper means to receive granules from the hopper means, at least one valve for controlling flow of granules to the tiles or similar articles and means to control the opening and closing of the valve randomly whereby granules can be caused to flow onto the tiles or similar articles in different quantities or arrangements.

The control means for operation of the valve means may conveniently comprise a random signal generator or generators wherein the or each valve is opened and closed in a random manner.

The or each random signal generator may comprise two pulse counters each of which provides an output on reception of a predetermined number of pulses since the previous output from the counter, a switching means which is arranged to be from a first state to a second state and vice versa on receipt of an output from a respective one of the pulse counters and to cause the provision of an output signal which is at a respective level according to the state of the switching means; a pair of pulse sources for each counter, at least one of the pulse generators providing pulses at a rate which is irregular and one of the pulse sources in each pair being arranged to provide pulses at a substantially higher frequency than does the other source in the same pair, and means responsive to the state of the switching means for controlling the provision of pulses to the counters and the provision of outputs from the counters to the switching means so that for each state of the switching means the counter of which the output will change that state to the other is fed by its respective lower frequency pulse source until an output from that counter is applied to the switching means and the other counter is fed with pulses from its higher frequency source without effect on the switching means.

The switching means preferably includes a bistable device providing complementary outputs in accordance with the particular state of the device and the means responsive to the state of the switching means preferably includes a coincidence gate which is controlled by a respective output from the bistable device and by an output from the respective counter. Each coincidence gate may inhibit the production of an output by the respective counter in accordance with the state of the bistable device.

The aforementioned sources may comprise, in each pair, a high frequency oscillator and a lower frequency oscillator: these oscillators may be connected to feed the respective counter alternatively.

Preferably means are provided for delaying the application of an output from the respective counter for switching the said switching means. This means for delaying may comprise an RC delay circuit between the respective coincidence gate and a respective control input of the bistable device.

There now follows a detailed description of a granule applicator adapted for use in a tile making plant, which description is to be read with reference to the drawings accompanying the Provisional Specification, it is to be understood that the applicator is described by way of example only and not by way of limitation of the invention.

In the aforementioned drawings: Figure 1 is a side view, generally in secZ tion, of an applicator and a portion of an assocated tile conveyor; Figure 2 is a view in the direction of arrow II of Figure 1; Figure 3 is a view in the direction of arrow III of Figure 1; Figure 4 is an enlarged view of some of the parts shown in Figure 1; and Figure 5 illustrates the random signal generator.

The granule applicator 1 provided by the invention comprises an open topped boxlike structure 2 fixedly mounted over a horizontal conveyor 3 along which freshly moulded tiles 4 are conveyed on tile pallets 5 in the direction of arrow A in Figure 1.

The box-like structure 2 is of fabricated metal plate and comprises first and second hoppers 6 and 7 defined by mutual side walls 8 and 9, see Figure 2 particularly, the first hopper 6 being further defined by a rear wall 10 extending between the side walls 8 and 9, the rear wall comprising a vertical portion 11 and a sloping portion 12 which extends downwardly and to the right, see Figure 1, to provide a bottom wall to the hopper 6.

The second hopper 7 is further defined by a front vertical wall 13 extending between the side walls 8 and 9. The two hoppers 6 and 7 are separated by a mutual wall 14 also extending between the side walls 8 and 9, the wall 14 having a short vertical portion 15 at its upper end, an intermediate portion 16 which extends downwardly from the portion 15 and towards the front wall 13, and a lower angled portion 17 joining the portion 16 to the front wall 13. The hopper 6 is more than twice the size of the hopper 7 and has its lower open end arranged overlying a sloping tray 18. The tray 18 is supported by a vibrator unit 19 which is in turn supported by flexible mountings 20 from the side walls 8 and 9 of the hoppers 6 and 7, thus to underlie the hopper 6.

The front wall 13 also defines a portion of the hopper 6 which underlies the hopper 7 and its lower end 21 terminates above an underside edge 22 of the hopper 6 to define a delivery aperture 23 for granules from the hopper 6 to the tray 18. The front wall 13 is also provided with a de- livery aperture 24 extending thereacross which lies coincident with a lower end 25 of the hopper 7 to facilitate delivery of granules from the hopper 7 to the tray 18.

The apertures 23 and 24 are arranged to be opened and closed by three gates 25, 26 and 27 mounted for vertical sliding movement adjacent the front wall 13. The gates 25, 26 and 27 are arranged in side by side relationship across the width of the applicator 1, see Figure 2. The gates 25, 26 and 27 each comprise a slide member 28 slidably mounted in a fixedly mounted slide block 29 for movement between a first operative position in which the portion of the delivery aperture 23 associated therewith is open as shown in Figure 1, and a second operation position in which a lower end 30 of the slide member blanks off its associated portion of the aperture 23, as shown in chain dot line in Figure 4.Each slide member 28 also comprises an aperture 31 which when the member 28 is in its second operative position is aligned with the aperture 24 in the front wall 13 as shown in chain dot line in Figure 4. To facilitate passage of granules from the hopper 7 through the apertures 24 and 31 the slide block 29 is also provided with a suitable aperture 32 coincident with the aperture 24. Each slide member 28 provides support for a bracket 33 through a horizontal portion of which a lower end of a piston rod 34 extends and is screwed thereto by lock nuts 35. An upper end of the piston rod is received in a cylinder 36 of a piston and cylinder arrangement, the cylinder 36 being fixedly mounted on a bracket 37 to the front wall 13 of the hopper 6 and 7.

Also mounted on the bracket 33 is a hood member 38 which is arranged to direct granules passing through the aligned apertures 24, 32 and 31 downwardly onto the tray 18. The applicator 1 provided by the present invention also comprises control means, comprising three random signal generators operation of which, when the applicator is in use, are effective to cause random operation of the gates 25, 26 and 27 respectively by providing signals to suitable fluid or solenoid operated valves, not shown, whereby the cylinders 36 are pressurised to cause upward or downward movement of their respective slide members 28 into or out of their first and second operative positions independently of one another.

Figure 5 illustrates one of the random signal generators which is a random multivibrator designed to generate a two state waveform of which both the mark and space are random within presettable limits.

The operation of this multi-vibrator is based on the fact that if a dividing counter or other counter which provides an output on reception of a predetermined number of pulses since the previous output is fed with a high frequency pulse train and this pulse train is gated on and off at a lower frequency then the counter will alternately count and stop for each cycle of the low gating frequency. Provided that the frequency of the high frequency pulse train is sufficiently greater than the frequency of the gating signal then the count at which the counter stops will Ibe random by virtue of random noise effects or can readily be made random. The source of the high frequency pulse train may be a clipped noise source but in the specific embodiment to be described an oscillator which does not possess high stability is used.

A pair of pulse sources is constituted by a high frequency oscillator 51 and a low frequency oscillator 52. An "OR" gate 53 couples the pulse outputs of the oscillators to the incrementing input of a counter 54.

For convenience this counter will be called the "space counter" because in effect it controls the duration of the space in a final output pulse waveform. The counter effects a division by a selected number N and thereby provides an output on reception of N pulses since the previous output. The output of the counter 54 is coupled to one input of a coincidence gate 55. The output of this coincidence gate is fed through a delay circuit 56 consisting of an adjustable series resistor and a shunt capacitor to one input of a bistable circuit 57. This circuit controls the mark to space ratio of the output waveform and has two complementary outputs. The output waveform is at "mark" if the bistable is switched by a signal from the coincidence gate 55 and the output waveform is at "space" if the bistable is switched by an output from a coincidence gate 62 to be described.

The generator also includes another pair of oscillators, namely a high frequency oscillator 58 and a low frequency oscillator 59 of which the outputs are coupled through an "OTC" gate 60 to a counter 61. This counter, called hereinafter "mark counter" is similar to the "space counter" 54. The output of the counter 61 is coupled to one input of a coincidence gate 62 of which the output is coupled through a delay circuit 63, similar to tbe circuit 56, to the bistable 57 to switch the bistable to a state hat causes the output waveform to be at space The "mark" output of the bistable is connected to one input of the coincidence gate 62 and also to enabling outputs of the oscilaltor 51 and the oscillator 59.The space output of the bistable 57 is connected to an input of the coincidence gate 55 and to enabling inputs of the low frequency oscillator 52 and high frequency oscillator 58. Each coincidence gate 55 and 62 is connected to an inhibiting input of the associated counter 54 and 61 respectively.

The multivibrator shown in Figure 5 works as follows. During a "mark" period the bistable 57 is in a state which enables the "mark" low frequency oscillator 59 and the "space" high frequency oscillator 51. Accordingly, the mark counter 61 is counting at a rate set by the low frequency oscillator whereas the space counter is counting at a high frequency as set by the high frequency oscillator 51. The output from the space counter is inhibited by the bistable 57 by means of the coincidence gate 55 and accordingly the counting by the space counter recirculates without effect on the bistable 57. Provided that the frequency of the oscillator 51 is not stable, the count at which the space counter rests when the coincidence gate 55 is open is random and may be in the range from 1 to N.Thus any number from 0 to (N-i) cycles of the oscillator 52 might be required to produce an output from the space counter 54. It will be seen that the mark counter is receiving pulses from the low frequency oscillator 59 while the space counter is recirculating. From the foregoing it will be understood that any number from 0 to (N-i) cycles of the oscillator 59 may be required to produce an output from the mark counter 61. When this random number of pulses is received, the bistable 57 is switched to the "space" state, which inhibits any further output from the counter 61 but now allows the counter 54 to be counted out by the oscillator 52.

The delays 56 and 63 ensure that the mark and space periods are not zero.

Where R is a random number between 0 and. (N-l) inclusive, the space time is equal to the sum of the delay of the circuit 56 added to the product of R and the period of oscillator 62, where R is a random number between 0 and (N-i). The mark time is the sum of the delay of circuit 63 and the product of R and the period of the oscillator 59.

The counters may be forced either to start from the count of zero (which starting produces a maximum "mark" or "space" time) or to remain at the count of N (which produces a minimum "mark" or "space" time); the random signal generator can then run stably. The enforcing of stable running of the generator facilitates the preparation of the generator for ordinary operation.

When the applicator 1 is in use in a tile making plant freshly moulded tiles 4 are conveyed on pallets 5 in spaced apart relationship by a conveyor 3 underneath the applicator 1. Before passing underneath the applicator 1 the tiles 4 on the pallets 5 are coated with a slurry to facilitate application and retention of granules applied to the upper surfaces of the tiles.

The slurry applied to the tiles 4 may be made up from cement, water and pigment, the cement-water ratio being chosen to give the slurry a suitable viscosity. Alternatively, the slurry may be made from sand, water and pigment also of suitable viscosity.

The hopper 6 is filled with granules of a first colour, e.g. red, and the hopper 7 is filled with granules of a second colour, e.g.

black. As the tiles 4 are conveyed beneath the applicator 1 as aforesaid, a mixture of red and black granules is applied to the upper surface.

This is achieved by operation of the random signal generator which causes random opening and closing of the gates 25, 26 and 27, whereby granules from the hoppers 6 and 7 flow through their respective apertures or are stopped from flowing therethrough. When the slide member 28 of a gate is open to allow red granules to flow from the hopper 6 it closes the aper ture of the hopper 7 to stop black granules flowing therefrom.

Granules flowing from the apertures 23 and 24 drop onto the tray 18 which, when the tile plant is in use, is being vibrated to create an even flow of granules over an edge 42 of the tray 18 and onto the slurry coated tiles.

A secondary tray or sheet, not shown, may be provided if the height of the tray 18 above the tiles is too high. Also where ridged tiles are being coated, baffle plates may be provided on the underside of the trays 18 and extending forwardly of the edge 42 to direct the granules in such a way that even coating of the ridged tiles is achieved.

Because the control means comprises the random signal generator, no two tiles are alike and thus in use the tiles when applied to a roof give an aesthetically pleasing finish wherein no recognisable pattern is evident in the finish of the tiles.

The size of the apertures 23 and 24 may be varied by adjustment of blanking off plates 40 and 41 respectively. Also, where the width of a tile being treated is narrower than those shown in the drawings, outermost side portions of the gates 25 and 27 may be blanked off in similar manner.

Other modifications may be made within the scope of the invention including the provision of a number of gates dependent upon the width and/or type of tile being coated with granules.

WHAT WE CLAIM IS:- 1. A granule applicator comprising

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (10)

**WARNING** start of CLMS field may overlap end of DESC **. to an input of the coincidence gate 55 and to enabling inputs of the low frequency oscillator 52 and high frequency oscillator 58. Each coincidence gate 55 and 62 is connected to an inhibiting input of the associated counter 54 and 61 respectively. The multivibrator shown in Figure 5 works as follows. During a "mark" period the bistable 57 is in a state which enables the "mark" low frequency oscillator 59 and the "space" high frequency oscillator 51. Accordingly, the mark counter 61 is counting at a rate set by the low frequency oscillator whereas the space counter is counting at a high frequency as set by the high frequency oscillator 51. The output from the space counter is inhibited by the bistable 57 by means of the coincidence gate 55 and accordingly the counting by the space counter recirculates without effect on the bistable 57. Provided that the frequency of the oscillator 51 is not stable, the count at which the space counter rests when the coincidence gate 55 is open is random and may be in the range from 1 to N.Thus any number from 0 to (N-i) cycles of the oscillator 52 might be required to produce an output from the space counter 54. It will be seen that the mark counter is receiving pulses from the low frequency oscillator 59 while the space counter is recirculating. From the foregoing it will be understood that any number from 0 to (N-i) cycles of the oscillator 59 may be required to produce an output from the mark counter 61. When this random number of pulses is received, the bistable 57 is switched to the "space" state, which inhibits any further output from the counter 61 but now allows the counter 54 to be counted out by the oscillator 52. The delays 56 and 63 ensure that the mark and space periods are not zero. Where R is a random number between 0 and. (N-l) inclusive, the space time is equal to the sum of the delay of the circuit 56 added to the product of R and the period of oscillator 62, where R is a random number between 0 and (N-i). The mark time is the sum of the delay of circuit 63 and the product of R and the period of the oscillator 59. The counters may be forced either to start from the count of zero (which starting produces a maximum "mark" or "space" time) or to remain at the count of N (which produces a minimum "mark" or "space" time); the random signal generator can then run stably. The enforcing of stable running of the generator facilitates the preparation of the generator for ordinary operation. When the applicator 1 is in use in a tile making plant freshly moulded tiles 4 are conveyed on pallets 5 in spaced apart relationship by a conveyor 3 underneath the applicator 1. Before passing underneath the applicator 1 the tiles 4 on the pallets 5 are coated with a slurry to facilitate application and retention of granules applied to the upper surfaces of the tiles. The slurry applied to the tiles 4 may be made up from cement, water and pigment, the cement-water ratio being chosen to give the slurry a suitable viscosity. Alternatively, the slurry may be made from sand, water and pigment also of suitable viscosity. The hopper 6 is filled with granules of a first colour, e.g. red, and the hopper 7 is filled with granules of a second colour, e.g. black. As the tiles 4 are conveyed beneath the applicator 1 as aforesaid, a mixture of red and black granules is applied to the upper surface. This is achieved by operation of the random signal generator which causes random opening and closing of the gates 25, 26 and 27, whereby granules from the hoppers 6 and 7 flow through their respective apertures or are stopped from flowing therethrough. When the slide member 28 of a gate is open to allow red granules to flow from the hopper 6 it closes the aper ture of the hopper 7 to stop black granules flowing therefrom. Granules flowing from the apertures 23 and 24 drop onto the tray 18 which, when the tile plant is in use, is being vibrated to create an even flow of granules over an edge 42 of the tray 18 and onto the slurry coated tiles. A secondary tray or sheet, not shown, may be provided if the height of the tray 18 above the tiles is too high. Also where ridged tiles are being coated, baffle plates may be provided on the underside of the trays 18 and extending forwardly of the edge 42 to direct the granules in such a way that even coating of the ridged tiles is achieved. Because the control means comprises the random signal generator, no two tiles are alike and thus in use the tiles when applied to a roof give an aesthetically pleasing finish wherein no recognisable pattern is evident in the finish of the tiles. The size of the apertures 23 and 24 may be varied by adjustment of blanking off plates 40 and 41 respectively. Also, where the width of a tile being treated is narrower than those shown in the drawings, outermost side portions of the gates 25 and 27 may be blanked off in similar manner. Other modifications may be made within the scope of the invention including the provision of a number of gates dependent upon the width and/or type of tile being coated with granules. WHAT WE CLAIM IS:-

1. A granule applicator comprising

hopper means for storing granules, and automatic means for continuously controlling the flow of granules from the hopper means randomly.

2. A granule applicator comprising hopper means for storing granules, means to feed a succession of tiles or similar articles past the hopper means to receive granules from the hopper means, at least one valve for controlling flow of granules to the tiles or similar articles and means to control the opening and closing of the valve randomly whereby granules can be caused to flow onto the tiles or similar articles in different quantities or arrangements.

3. A granule applicator according to claim 2 in which the control means for operation of the valve means comprise a random signal generator or generators whereby the valve or each valve is opened and closed in a random manner.

4. A granule applicator according to claim 3, in which the or each random signal generator comprises two pulse counters each of which provides an output on reception of a predetermined number of pulses since the previous output from the counter, a switching means which is arranged to be from a first state to a second state and vice versa on receipt of an output from a respective one of the pulse counters and to cause the provision of an output signal which is at a respective level according to the state of the switching means; a pair of pulse sources for each counter, at least one of the pulse generators providing pulses at a rate which is irregular and one of the pulse sources in each pair being arranged to provide pulses at a substantially higher frequency than does the other source in the same pair, and means responsive to the state of the switching means for controlling the provision of pulses to the counters and the provision of outputs from the counters to the switching means so that for each state of the switching means the counter of which the output will change that state to the other is fed by its respective lower frequency pulse source until an output from that counter is applied to the switching means and the other counter is fed with pulses from its higher frequency pulse source without effect on the switching means.

5. A granule applicator according to claim 4 in which the switching means includes a bistable device providing complementary outputs in accordance with the particular state of the device and the means responsive to the state of the switching means includes a coincidence gate which is controlled by a respective output from the bistable device and by an output from the respective counter.

6. A granule applicator according to claim 5 in which each coincidence gate inhibits the production of an output by the respective counter in accordance with the state of the bistable device.

7. A granule applicator according to any of claims 4 to 6 in which the aforementioned sources comprise, in each pair, a high frequency oscillator and a lower frequency oscillator.

8. A granule applicator according to any of claims 4 to 7 in which means are provided for delaying the application of an output from the respective counter for switching the said switching means.

9. A granule applicator according to claims 5 and 8 in which the means for delaying comprises an RC delay circuit between the respective coincidence gate and a respective control input of the bistable device.

10. A granule applicator, suitable for use in a tile making plant, substantially as hereinbefore described with reference to the drawings accompanying the Provisional specification.