APPARATUS AND METHOD FOR USE IN THE MANUFACTURE OF TILES

Abstract: Individual abutting pallets (A, B and C) containing moulded concrete or the like to form roof tiles, are supplied to a primary chain conveyor (4) which feeds them to a secondary chain conveyor (5), both conveyors moving the pallets by means of pawls engaging in a recess in the underside of each pallet. The second conveyor moves at a faster speed than the first conveyor and thus the pallets are moved apart. A reciprocating carriage (30) carries tools such as a corner cutter (41) and hole punch (40). In the forward direction it moves at the same speed as the secondary conveyor. The tools are operated in synchronisation with the positions of the pawls on the secondary conveyor.

Description: Apparatus and method for use in the manufacture of tiles This invention relates to an apparatus and method for performing operations such as corner cutting, hole punching, embossment etc on newly formed tiles, such as roof tiles, slates or the like as they are conveyed on pallets in a manufacturing line. Roof tiles, slates etc are traditionally manufactured by a process wherein tile-forming material * such as concrete from a hopper is extruded in a layer onto a plurality of individual moving pallets and is then severed by a synchronised cutter, for example carried on a reciprocating carriage, to leave an individual tile moulding formed on each pallet. The pallets are then conveyed in a line from the hopper and cutter to a storage or discharge station, the tile forming material hardening as the pallets are conveyed. For certain types of tile it is desirable to perform further operations on the tiles after extrusion. For example, certain types of tile and slate have a corner cut off their trailing edge, some tiles may be given shaped leading edges and some types also include nail holes for securing the tiles to the roof battens in use. In known arrangements practical problems arise in seeking to perform such punching and cutting operations on moving tiles, which is desirable if the process is to be fully automated into the tile conveying line. In one conventional machine for making concrete roof tiles, the pallets are pushed through the machine in the region of the hopper. A chain conveyor is provided on which are mounted pawls to engage in recesses formed towards the front end of the underside of each pallet. In one known arrangement only one pallet is directly driven by a pawl at any given time. The pallets in front all abut and are pushed along indirectly. The pallets must abut as they pass through the extrusion region or the concrete could not be laid down properly. As a new pallet reaches the region of the chain conveyor, a pawl comes into contact with its recess and at the same time the preceding pallet ceases to be driven directly and its pawl moves out of its recess. Typically there may be ten pallets between a driving pawl and a cutting unit after extrusion has taken place. For certain forming operations such as cutting corners or punching holes it is necessary for there to be accurate positioning of the relevant tool with respect to the moulded tile in its pallet. This presents problems in conventional machines, since it is difficult to establish absolute positional control with respect to an individual pallet. According to the invention there is provided apparatus for use in the manufacture of tiles, comprising means for conveying a continuous series of pallets through an extruding station where tile forming material is extruded as a continuous layer onto the pallets, -and means for cutting the layer into lengths so as to form an individual tile moulding on each pallet, wherein there are provided means for separating the pallets with the individual tile mouldings thereon, means for directly driving the individual pallets, and means for carrying out a further operation on the individual tile mouldings in synchronisation with the position of the direct driving means for the respective individual pallets, whilst the individual pallets are being driven by the direct driving means. Thus, a corner cutter, nail puncher or the like •will be synchronised directly with the particular pallet carrying the tile moulding on which the operation is to be carried out. This is in contrast to e.g. the cutting of the layer of extruded material immediately after extrusion, where synchronisation can only be effected between the cutter and the pawl driving a pallet which may be several places back in the row when using certain conventional apparatus. Tolerance build up along the row in such conventional apparatus can result in significant misalignments which may be acceptable for basic cutting of the layer but will be unacceptable for the precision placement of nail holes, cutting corners and so forth. By means of the invention it is possible to produce tiles with accurately shaped leading and/or trailing edges, accurately positioned nail holes or corner cuts, and so forth. - Manufacturing tolerances will only relate to a single pallet so that any misalignments will be. minor and will not be built up over a series of pallets. In a preferred embodiment, the direct driving means is a further chain conveyor with pawls thereon for engaging recesses in the underside of the pallets. Since the pallets are separated, each is driven independently by a pawl and each will be synchronised accurately with the means carrying out the further operation. In conventional apparatus, the basic cutting operation carried out on the continuous layer will separate the pallets. In some cases this separation operation may be sufficient and the pallets can pass to be directly driven for the further operations. However, in practice delays occur downstream of the cutting station and this will give rise to queues of abutting pallets. This could be controlled by means of electronic circuitry and e.g. counting means to ensure that the supply of separated pallets from the cutting station does not exceed the capacity of apparatus downstream. Preferably, however, means are provided downstream of the cutting station, for ensuring that the pallets are separated. Thus in a preferred embodiment the means for _ • _ directly driving the individual pallets, is supplied with pallets from conveying means which supplies the pallets at a speed slower than that of which they are conveyed on the direct driving means. Thus, the pallets will be accelerated as they are taken up by the direct driving means, and gaps will be created between them. The creation of gaps not only ensures that there can be accurate synchronisation. It prevents pallets being displaced from their desired positions by a knock- on offset from pallets upstream. Furthermore, for a corner cutting . operation the cut portions from the trailing edge may be removed via the gaps. The extruding station may be of a conventional type including a hopper for holding the wet concrete, a • mixer-up if desired, such as a paddle wheel, a shaping roller and a slipper plate. The invention also provides a process for manufacturing tiles, comprising the steps of conveying a continuous series of pallets through an extruding station, extruding tile forming material as a continuous layer onto the pallets, cutting the layer to form individual tile mouldings on each pallet, separating the pallets, directly driving the individual pallets, and carrying out a further operation on the individual tile mouldings in synchronisation with the positions of the respective individual pallets whilst being driven directly. Whilst the invention is of particular use in the manufacture of concrete roof tiles, it is also applicable to the manufacture of other tiles such as vertical cladding tiles, clay tiles and so forth. Viewed from another aspect the invention provides apparatus for use in the manufacture of tiles, comprising first conveying means for receiving a plurality of pallets containing tile mouldings, and conveying them at a first speed in a longitudinal direction, and second conveying means for receiving pallets from the first conveying means and conveying them at a second, higher speed in the longitudinal direction, the second conveying means having driving means for positively engaging a predefined portion of each pallet, and there being forming means for carrying out a forming operation on the tile mouldings whilst being conveyed by the second conveying means, said forming means being reciprocable in the longitudinal direction, having a speed in the direction of conveying which corresponds to said second speed and being operable in synchronisation with the positions of the driving means on the second conveying means. In a preferred embodiment there are provided downstream of the basic cutting station, primary and secondary conveyors arranged longitudinally of one another, with the secondary conveyor operating at a higher speed than the primary conveyor to accelerate the pallets to define gaps therebetween as described. The conveyors preferably include spaced pawls for engaging recesses on the underside of the tile pallets. The pawls of the secondary conveyor, which constitutes the direct driving means, are so positioned relative to a reciprocating tool carrying carriage whereby a desired positional relationship between each pallet and the carriage during its forward stroke is achieved. The primary and secondary conveyors may be chain conveyors, the drives of which are suitably synchronised so that pallets move smoothly from one to the other. A preferred embodiment includes a cord conveyor upstream of and operable at a slightly lower speed than the primary conveyor, carrying pallets ' from the basic cutting station whereby a queue of tiles waiting to be taken up by the primary corner is formed. Preferably, sensors are provided adjacent or upstream of the cord conveyor to monitor the length of the queue, a control means responsive to the sensors being adapted to speed up or slow down the conveying means of the apparatus as appropriate to maintain the length of the queue within predetermined limits to accommodate for changes in the delivery rate of the upstream tile manufacturing process. A pallet brake may be provided to restrain the forwardmost pallet in the queue from knocking ' into and disturbing the position of the pallets already within the apparatus in the event of -a shut down. At the downstream end of the apparatus a further cord conveyor may be arranged to receive pallets from the secondary conveyor and discharge them onto a further conveying line. To carry out the further operations on the individual tile mouldings, there is preferably provided a carriage located above and reciprocable back and forth in the direction of movement of the direct driving means, the carriage mounting one or more devices for performing operations on tiles carried by the pallets, and means for driving the carriage in synchronism with the direct driving means so that the movement of the carriage during each forward stroke is synchronised with the movement of a respective pallet being conveyed beneath the carriage. Thus, operations such as corner cutting, hole punching, feature cutting, embossing etc may be carried out on moving tiles whilst conveyed in a line by means of devices which move with the tile forming pallets whilst the operations take place. The operations take place during the forward stroke of the carriage, which is then returned to its starting position for movement with the next pallet, and so on. Other synchronisable operating means might be provided in place of the carriage arrangement, such as a rotating wheel or drum. Reciprocable carriages are known per se, for example from U.S. Patent 2,177,607 which also shows a tile with a corner cut. It will be appreciated that the operating devices may vary depending on the type of tile being produced. In one embodiment, the carriage is provided with two hole punches and two corner cutters, each of which is pneumatically or mechanically operable in synchronism with the carriage so as to be lowered into engagement with a tile during each forward stroke of the carriage and raised during each reverse stroke. As mentioned above, for a corner cutting operation it may be advantageous for corner portions to be cut from the trailing edge of each tile and removed via the gaps. Thus, in a preferred embodiment, the corner cutting devices are left in their lowered positions for the initial part of the return stroke of the carriage for sufficient time to separate longitudinally the cut corners from the tile and move them into the gap from where they can be removed e.g. by an air blower. In a preferred embodiment, the various conveyors of the apparatus are driven from the same common drive means e.g. an electric motor via a suitable arrangement of drive chains and sprockets. Preferably, the reciprocating carriage is driven by a link member pivotally carried by a pin extending between drive chain loops arranged side by side and driven at the same speed as the secondary synchronising conveyor whereby the desired movement of the carriage back and forth is achieved. After the further operation have been carried out the tile mouldings on their pallets may be discharged onto a further transport conveyor leading to storage/packing stations etc. An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, wherein: Figure 1 is a schematic and partly broken away perspective view from one side of apparatus for carrying out operations on tile mouldings; Figure 2 is a schematic perspective view from the other side of the apparatus with certain parts removed for clarity; and Figures 3a to 3i are partly broken away schematic side elevations illustrating the operational sequence of the apparatus in use. Referring firstly to Figure 1, apparatus in accordance with the invention comprises main supporting side plates 1, 2 between which a number of axles (to be described later) extend. The apparatus is adapted to be disposed in a conveying line carrying roof tile forming pallets so that pallets are introduced into the apparatus at one end and are conveyed out at the other end as shown by the arrows in Figure 1. In practice, the apparatus is located downstream of a hopper and cutting device at which tile forming material is introduced onto a plurality of successive pallets. Such an arrangement is conventional in the manufacture of roof tiles, slates etc and does not need to be described further herein. One example of a basic tile making machine is disclosed in Fig. 1 of PCT publication WO- 85/00135, the contents of which are imported herein by way of reference. The -present apparatus includes four longitudinally spaced conveyers for the tile pallets, namely an arrester cord conveyer 3, a primary chain drive conveyor 4, a secondary chain drive conveyor 5 and an outlet cord conveyor 6. The arrester conveyor is arranged to receive pallets from an upstream conveyor (not shown) which leads from the hopper etc. The cord conveyors 3, 6 each comprise laterally spaced cords extending around spindles 7 carried by respective axles 8, 9, 10, 11. Of these, the axle 10 also carries sprockets for the chain drive mechanism as described in more detail below. The arrangement of the cord conveyors 3 , 6 is such that the pallets are supported at each lateral edge on the cords and moved along with the cords. The primary and secondary chain drive conveyors 4 , 5 are arranged to transport the pallets between the cord conveyors 3, 6. Each of the chain drive conveyors includes pawls 12 , 12 ' arranged to engage in recesses formed towards the front end of the underside of each pallet. In the illustrated embodiment, each of the chain drive conveyors is provided with four such pawls 12 , 12 ' , with the spacings between the pawls 12 ' on the secondary conveyor being slightly greater than the spacings between the pawls 12 on the primary conveyor for the reasons discussed below. All of the conveyors of the apparatus are driven by a single electric motor 13 by the chain drive arrangement illustrated schematically in Figures 1 " and 2. A motor output sprocket 14 (not shown in Figure 2) is coupled to a drive input sprocket 15 carried by and drivingly coupled to the axle 10. As shown most clearly in Figure 2 , such axle 10 thus provides the drive for the outlet conveyor 6 and the secondary chain conveyor 5, whereby these conveyors operate at the same speed and each pallet can move smoothly from the conveyor 5 to the outlet conveyor 6. The upstream sprocket 17 of the secondary chain conveyor 5 free wheels on a further axle 18. However, referring ba ' ck to Figure 1 (which illustrates the other side of the apparatus) the axle 18 is itself driven from the other end of the rotating shaft 10 via a drive chain 19, the sprockets 20, 21 of which are of unequal sizes so that the axle 18 rotates at a slightly lower speed than the axle 10. Fixedly mounted on the axle 18 (side by side with the free-wheeling sprocket 17) is a drive sprocket 23 for the primary chain drive conveyor 4. The other end of the primary chain drive conveyor extends around a free-wheeling sprocket 24 mounted on a non- rotating axle 25. The rotating axle 18 is also coupled via a chain drive 26 to rotating axle 9 which, as described above, carries the downstream spindles of the arrester cord conveyor 3, the upstream free-wheeling spindles 7 of which are on the axle 8. The arrangement is such that the arrester conveyor is driven at a slightly slower speed than the primary chain conveyor, whereby a queue of tile pallets builds up on the arrester conveyor waiting to be picked up by successive pawls 12 of the primary chain conveyor 4. The free-wheeling upstream sprocket 17 of the secondary chain drive conveyor 5 and the drive sprocket 23 of the primary chain drive conveyor lie side by side and, by virtue of the differing sizes of sprockets 20, 21 rotate at slightly different speeds. The pawls 12' of the secondary chain conveyor are spaced apart at a distance greater than that between the pawls 12 on the primary conveyor such that the ratio of these distances is equal to the ratio between the drive speeds of the conveyors. The pawls on each of the chain conveyors are also arranged so that respective pawls 12, 12' align exactly with one another each time they pass top dead centre with respect to the sprockets 17, 23. In this way, each time a pallet reaches the front of the primary chain conveyor 4 it is picked up by a pawl 12 ' of the secondary conveyor and carried thereby, as will be described in more detail below. As shown most clearly in Figure 2, the apparatus further includes a reciprocating carriage assembly 30 having a framework 31 mounted by means of rollers 32 on tracks 33 disposed generally above the secondary chain drive conveyor 5. The carriage assembly 30 is moveable back and forth along the tracks 33 under the drive of a linkage 36 which is pivotally carried at its other end by a pin P extending between chains 38, located on sprockets 37, one of which is driven from the rotating axle 10 via a chain 39. The arrangement is such that the carriage reciprocates under the drive of linkage 36 back and forth above the secondary chain conveyor, and during each forward stroke the carriage is synchronised with a respective pawl 12' moving thereunder. Accordingly, the forward movement of operating devices 40, 41 carried by the carriage 30 is likewise synchronised with the movement of each tile pallet on the secondary chain drive conveyor 5. In the illustrated embodiment, the operating devices 40 constitute punches for forming nail holes in the tiles carried by the pallet, whereas the devices 41 (of which only one is illustrated in the drawings for clarity) constitute corner cutters for cutting a segment out of corner regions of the trailing tile edges. Other operating devices may be carried by the carriage, such as feature cutters, embossing tools etc. The downward displacement of the operating devices 40, 41 may be suitably synchronized with the movement of the carriage and pallets by means of a microprocessor (not shown) which receives position pulses from the apparatus drive mechanism. The operating devices 40, 41 are preferably pneumatically actuated. At the upstream end of the apparatus a pallet brake 45 is provided. This is adapted to restrain the leading pallet in the queue forming on a conveyor upstream of the apparatus each time the apparatus is shut down. The pallet brake is also preferably pneumatically actuated, and the purpose of the brake is to prevent, at shutdown, a 'billiard ball' or knock on effect of moving tiles from behind engaging stationary ones within the apparatus which could disturb the positionaj. relationship between the pawl.s and pallets. This might otherwise cause the apparatus to operate out of synchronism on subsequent start up. The apparatus also preferably includes sensors (not shown) located upstream which detect the length of the queue of pallets on the upstream conveyor waiting to pass through the apparatus. The microprocessor control preferably includes means responsive to the sensors to speed up or reduce the speed of the conveyors of the apparatus so that the length of the queue remains within predetermined limits regardless of the speed of tile production from the upstream hopper. The sequence of operation of the apparatus will now be described with reference to -Figures 3a to 3i. In some of these figures, certain parts are removed for clarity. - As shown in Figure 3b a tile forming pallet A passes firstly onto the arrester conveyor and moves therealong until it is picked up by a pawl- 12 of the primary chain drive conveyor, the pawl 12 engaging in a recess 46 on the underside of the pallet adjacent the front edge thereof (such recesses are traditionally provided in tile forming pallets and define on the upper surface of the pallet a mould for the nib of the tile, as will be appreciated by those versed in this art) . As shown in Figure 3c, the tile pallet A is then moved forwardly by the primary chain drive conveyor and the next tile B moves onto the arrester conveyor immediately behind the first tile A. The second tile B is then engaged by the next pawl 12 and so on. The spacings between the pawls 12 on the primary chain drive conveyor correspond to the length of the tile pallets whereby tiles carried by the primary chain drive conveyor abut one another as shown Figure 3c. At the position shown in Figure 3d the leading tile A is engaged by a pawl 12 ' of the secondary chain drive conveyor which, at that position, aligns with the pawl 12 of the first conveyor which originally picked up that tile. The pawls 12' or 12 are laterally displaced so that there is no collision in the region of the recess, which will be wide enough to receive a pawl in either lateral position. A third tile C is meanwhile being engaged by a further pawl of the primary chain drive conveyor. As shown in Figure 3e, by virtue of the fact that the secondary chain drive conveyor moves faster than the first chain conveyor (the pawls thereof being correspondingly further spaced apart so that the pawls 12, 12' pass top dead centre with respect to sprockets 17, 23 in synchronism) , the tiles A, B become spaced apart by an increasing distance as the tile A is conveyed by the secondary chain conveyor. This provides three advantages. Firstly, the spacing between the tiles avoids a possible knock-on or 'billiard ball' effect of the tiles banging into each other which might otherwise disturb correct alignment. Secondly, the gap between the tiles enables longitudinal withdrawal of material cut from the tile corners by the device 41 as described below. Thirdly, it is possible to drive the pallets individually and synchronise operations to individual pallets. As discussed " above, the carriage 30 is synchronized, during its forward stroke, with the tile pallet moving thereunder i.e. there is no relative longitudinal movement between the operating devices 40, 41 and the tile pallets during part of each pallet's movement by the secondary conveyor 5. As shown in Figure 3f, during the initial part of the forward stroke of the carriage the hole punch device 40 and the corner cutter device 41 are actuated so that their cutting edges extend downwardly through the tile material carried in the pallet. As shown in Figure 3g, when the carriage 30 reaches the front of its stroke the nail punch device 40 is immediately retracted, so that the pallet can continue to move forwardly from beneath the forwardmost position of the carriage 30. However, as shown in Figure 3h the corner cutting device is left downwardly displaced for the initial part of the return stroke of the carriage 30. The effect of this is that material cut from the tile corners by such device is displaced rearwardly by the cutter with respect to the forwardly moving tile and can be removed via the longitudinal gap defined between the tiles A, B e.g. by an air blower. As shown in Figure 3i the first tile A is then moved onto the outlet cord conveyor 6 and the next tile B is taken up by the secondary chain conveyor, whilst the carriage is returned to its initial position with both operating devices raised. A fourth tile D is meanwhile engaged by the primary chain conveyor and so on so that operation is continuous. As discussed above, an advantage of this apparatus is that the operating devices 40, 41 move in synchronism with the tile pallet during operation thereof so that there is no relative longitudinal movement between the devices and the tile forming material being punched, cut or otherwise treated. In an alternative arrangements for corner cutting, the corner cutter could be arranged to push the out portion sideways away from the tile, for example by being pivoted about a horizontal axis extending in the longitudinal direction of the apparatus.

Claims: CLAIMS 1. Apparatus for use in the manufacture of tiles, comprising means for conveying a continuous series of pallets through an extruding station where tile forming material is extruded as a continuous layer onto the pallets, and means for cutting ' the layer into lengths so as to form an individual tile moulding on each pallet, wherein there are provided means for separating the pallets with the individual tile mouldings thereon, means for directly driving the individual pallets, and means for carrying out a further operation on the individual tile ' mouldings in synchronisation with the position of the direct driving means for the respective individual pallets, whilst the individual pallets are being driven by the direct driving means. 2. Apparatus as claimed in claim 1 wherein the means for directly driving the individual pallets comprises a conveyor having an individual element thereon for engaging a predetermined portion of a pallet. 3. Apparatus as claimed in claim 2 wherein the element on the conveyor is a pawl adapted to engage in a recess in a pallet. 4. Apparatus as claimed in claim 1, 2 or 3 wherein the means for separating the pallets includes a primary conveyor for supplying pallets to the means for directly driving the pallets, at a speed lower than the speed of the direct driving means. 5. Apparatus as claimed in claim 3 wherein the primary conveyor has a pawl thereon adapted to engage a pallet. 6. Apparatus as caimed in claim 4 or 5 including means for forming a queue of pallets from which the primary conveyor is supplied. 7. Apparatus as claimed in any preceding claim wherein the means for carrying out a further operation on the tile mouldings is reciprocable in the direction of movement of the pallets driven by the direct driving means and is movable in the direction of forward .. movement at the same speed as the direct driving means. 8. Apparatus as claimed in any preceding claim wherein the further operation to be carried out includes a forming operation in which a forming member is urged into contact with a tile moulding. 9. A process for manufacturing tiles, comprising the steps of conveying a continuous series of pallets through an extruding station, extruding tile forming material as a continuous layer onto the pallets, cutting the layer to form individual tile mouldings on each pallet, separating the pallets, directly driving the individual pallets, and carrying out a further operation on the individual tile mouldings in synchronisation with the positions of the respective individual pallets whilst being driven directly. 10. Apparatus for use in the manufacture of tiles, comprising first conveying means for receiving a plurality of pallets containing tile mouldings, and conveying them at a first speed in a longitudinal direction, and second conveying means for receiving pallets from the first conveying means and conveying them at a second, higher speed in the longitudinal direction, the second conveying means having driving means for positively engaging a predefined portion of each pallet, and there being forming means for carrying out a forming operation on the tile mouldings whilst being conveyed by the second conveying means, the forming means being reciprocable in the longitudinal direction, having a speed in the direction of conveying which corresponds to said second speed, and being operable in synchronisation with the position of the driving means on the second conveying means.

Inventors: PALMER MICHAEL ANTHONY, PALMER, MICHAEL, ANTHONY
Applicants: MARLEY TILE AG, MARLEY UK LIMITED, MARLEY (UK) LIMITED
Application year: 1990
Main classification: B65G47
IPC codes: B28B11, B28B17, B65G47