IMPROVEMENTS IN THE MANUFACTURE OF ROOF TILES

Abstract: The manufacture of concrete roof tiles with cut-back sidelock portions is improved by moulding the tiles on novel palets (P2) which themselves are provided with cut-away portions (36) coincident with the cut-back sidelocks (34) to be formed in the tiles (2). A knife cutting attachment (22) is provided, which, when a ribbon of mortar has been formed in a line of pallets, is effective to cut the ribbon of mortar (26) to form discrete tiles (2) on said pallets (P2) and coincident therewith to cut back the sidelock portions (34) of the tiles (2) so formed which sidelock portions are "flash" free due to the cooperation of the knife cutting attachment (22, 40, 43, 43, 44) with the cut-away portions (36) of the novel pallets. The improved tiles are more aesthetically pleasing than de-flashed tiles used hitherto.

Description: Improvements in the Manufacture of Roof Tiles This invention is concerned with improvements in or relating to the manufacture of concrete roof tiles. Concrete roof tiles are in the main formed by the well known roller and slipper process in which tile pallets are fed seriatim beneath the mortar hopper of a tile making machine, whereat when the machine is in use, mortar is fed onto the pallets to form a continuous ribbon thereon. Downstream of the mortar hopper, a cutting mechanism of the tile making machine is operated to cut the ribbon of mortar to form discrete "green state" tiles on the individual pallets which "green state" tiles are thereafter cured by conventional means. If other portions ofthe tiles are to be cut to provide cut-away portions, it is usual to provide extra knives, or the like, for severing the appropriate portion or portions. With tiles which are to be provided with side-lock portions which are cut away at "toe" and/or "head" ends of the tiles, i.e. at the lower or upper ends thereof in use, one way of achieving such a feature in the "green state" tiles is to provide an extension portion, to the knife or knives used to cut the tiles into discrete lengths, see GB 2198073B. The novel cutting mechanism of GB 2198073B was intended to ensure that the cut-away sidelock portion of a "green state" tile is removed effectively from the remainder of the tile such that the tile is undamaged and little or no detritus remains on the tile. This problem was only partially overcome by the use of the cutting mechanism of GB2198073B and remains particularly evident in extruded concrete tiles due to the nature of the material from which the tiles are made since the materials may vary considerably from plant to plant depending upon the grades of sands, etc., which are available for the manufacture of concrete roofing tiles. ln addition, because the knife ofthe cutting mechanism cuts onto the tile pallet in blanking out a sidelock feature in the tile produced thereon, a residual "flash" is evident around the bottom edge of the "green state" tile and particularly in the corner area of the cut-out sidelock feature, which "flash" may interfere with the laying of the cured tiles unless a roofer deflashes the tile. Of late, it has become convenient to manufacture some concrete tiles upside down on their tile pallets, i.e. by forming the upper surface thereof, in use on a roof, on the tile pallet and forming the undersurface by the conventional roller and slipper method. Where such tiles are also provided with a cut-back sidelock feature, the "flash" manifests itself around and particularly at the corner area of the cut-out feature of the tile. Thus, if a flash has to be removed from the cured tile before use, in addition to the extra deflashing operation, the tiles may be impaired at their upper surface adjacent the cut¬ back sidelock portion to the detriment of the aesthetic appeal of the tiles laid on a roof. It is thus one ofthe objects ofthe present invention that these disadvantages be mitigated or overcome. To this end, the present invention provides a process for the manufacture of roof tiles with cut-back sidelock portions comprising the steps of: a) feeding a series of pallets seriatim beneath a hopper containing tile mortar; b) causing the tile mortar to be fed from the hopper onto the series of pallets to form a continuous ribbon of mortar thereon; and, c) causing the operation of a cutting mechanism whereby a knife controlled thereby severs the ribbon of mortar at the joints between successive pallets of the series of pallets; characterised in that the pallets used in the process are provided with cut-away portions at a corner portion thereof coincident with cut-away portions of roof tiles formed on said pallets during said process. Preferably, the invention provides a process according to the last preceding paragraph further characterised by the function of the cutting mechanism, operation of which when the process is effected, causes the knife controlled thereby to cut completely through the mortar at the cut-away corner portions of the pallets to provide "green state" tiles with flash-free cut-back sidelock portions. Conveniently, the invention also provides a pallet for use in the manufacture of a cut-back sidelock roof tile, said pallet comprising a cut-away portion to facilitate, in use, the manufacture of a flash-free cut-back sidelock portion in a tile formed on said pallet. The invention also conveniently provides a tile having a flash-free cut-back sidelock portion produced by the processes and pallets of the last three preceding paragraphs. There now follows by way of example of the present invention a detailed description of the novel process for the production of roof tiles, which description is to be read with reference to the accompanying drawings in which: Figure 1 is a diagrammatic side elevation of a conventional tile making machine; Figures 2a and 2b are top and underside plan views respectively of a roof tile; Figures 3a and 3b are top and underside plan views respectively of a pallet for the production of the tile of Figures 2a and 2b: Figures 4a and 4b are top and underside plan views respectively of a modified pallet provided by the invention; Figure 5 is a fragmental upper perspective view of parts seen in Figure 1 ; Figure 6 is a fragmental diagrammatic plan view of parts seen in Figures 1 and 5; Figures 7a and 7b are fragmental underside and side elevations respectively ofthe sidelock portions of tiles formed on prior art pallets; Figures 8a and 8b are fragmental underside and side elevations respectively ofthe sidelock portions of tiles formed on pallets of the present invention; and, Figure 9 is a fragmental side elevation of a knife of Figure 5 in use. In the manufacture of concrete roof tiles by conventional tile processing methods, the cut¬ back sidelock feature 2, see Figures 7a and 7b is often embellished with a "flash" of uncut mortar. This "flash" causes difficulties when laying the tiles on a roof unless- a costly "deflashing" operation is carried out. In addition, where tiles are formed upside down on their pallets, the "deflashing" operation may cause damage to the upper surface in use ofthe tiles adjacent the cut-back sidelock portion. In the novel process provided by the present invention, tiles 2 are produced on a conven¬ tional tile machine 4 shown in Figure 1 , which tile machine 4 comprises a hopper 8 located overlying a pallet conveyor 12. The conveyor 12 is of conventional design, is supported on floor mounted columns 12a and 12b and comprises support rails 12c on which pallets P2 are supported as they pass seriatim beneath the hopper 8. The hopper 8 is also of conventional design and provides support for a roller 13, a slipper 14 and a pack shaft 16. Located above the hopper 8 is a material feed conveyor 18 for feeding mortar to the hopper, see Figure 1. Downstream of the hopper 8, the tile making machine is provided with a conventional tile cutting knife 20 which is mounted for reciprocal vertical and longitudinal movement on a knife carriage 22 illustrated schematically in Figure 1. The tile making machine also comprises a pallet spacing conveyor 24 which is arranged beneath the conveyor 12 and adjacent the knife carriage 22 for accelerating pallets P2 at the head of a series of such pallets away from the remaining pallets ofthe series. When the machine of Figure 1 is in use in the manufacture of concrete roofing tiles 2, a batch of mortar is fed by the conveyor 18 to the hopper 8. At the same time, pallets P2 are fed seriatim along the support rails 12c of the conveyor 12 so that mortar in hopper 8 is compacted by the packshaft 16, to be thereafter formed, by the roller 13 and slipper 14, as a continuous ribbon 26 of "green state" mortar on the pallets P2. The ribbon 26 of "green state" mortar is thereafter cut by the knife 20 of the tile cutting arrangement 22 whereupon trailing ends ofthe pallets P2 are engaged by the conveyor 24 whereby the "green state" tiles 2 on their associated pallets P2 are conveyed to racking devices prior to transportation to curing chambers. If the tiles 2 are produced on pallets P1 as used hitherto, see Figures 3a and 3b, a residual "flash" 33 is evident at a lower edge portion 30 of a cut-back sidelock portion 32 of the tile 2, see especially Figures 7a and 7b. This "flash" feature hinders the current laying of the tile and has to be removed by a deflashing operation before the tiles 2 can be used. The pallets P2 of the present invention, on the other hand, enable the production of "flash" free cut-away sidelock portions 34, see especially Figure 8a and 8b. The "flash" free portions 34 are produced by using the pallets P2, which are themselves provided with a cut-away portion 36 at a lower end portion 38 of the tile, see Figures 4a and 4b. The cut-away portions 36 of the pallets P2 are coincident with the to be cut¬ away sidelock portions 34 of the tile 2 formed on said pallets P2. To delineate and cut out said sidelock portions 34, the knife 20 comprises a first blade portion 40 for effecting the cutting of the ribbon of mortar 26 at a joint of successive pallets P2. The knife 20 also comprises a second blade portion 42 extending rearwardly at an angle normal to or substantially normal to the portion 40 as shown in Figures 5 and 6. The knife 20 further comprises a third blade portion 44 extending from a rearward end 43 of the blade portion 42 at an angle normal to or substantially normal to the portion 42 and parallel to, or substantially parallel to, the blade portion 40, see Figures 5 and 6. Lower end portions 40a, 42a and 44a, i.e. the cutting portions of the blade portions 40, 42 and 44 are conventionally arranged in the same plane to effect the cutting of the portion 34. This facilitates the complete cutting away of the sidelock portions 34 of the tiles 2 when the portion 40a has cut through the ribbon of mortar 26 to a depth coincident with upper surfaces ofthe pallets P2, see Figure 9. It will be readily appreciated that when forming tiles upside down, the present invention facilitates the forming of "flash"-free cut-away sidelock portions in the finished products thereby obviating the need to perform a deflashing operation which in the past has led to the upper surfaces, in use, ofthe tiles being damaged.

Claims: CLAIMS A process for the manufacture of roof tiles with cut-back portions comprising the steps of: a) feeding a series of pallets seriatim beneath a hopper containing tile mortar; b) causing the tile mortar to be fed from the hopper onto the series of pallets to form a continuous ribbon of mortar thereon; and, c) causing the operation of a cutting mechanism whereby a knife controlled thereby severs the ribbon of mortar at the joints between successive pallets of the series of pallets; characterised in that the pallets used in the process are provided with cut-away portions at a corner portion thereof coincident with cut-away portions of roof tiles formed on said pallets during said process. A process according to Claim 1 further characterised by the function of the cutting mechanism, operation of which when the process is effected, causes the knife controlled thereby to cut completely through the mortar at the cut-away corner portions ofthe pallets to provide "green state" tiles with flash-free cut-back sidelock portions. A pallet for use in the manufacture of a cut-back sidelock roof tile, said pallet comprising a cut-away portion to facilitate, in use, the manufacture of a flash-free cut-back sidelock portion in a tile formed on said pallet. A tile having a flash-free cut-back sidelock portion produced by the processes of Claims 1 and 2 using the pallet of Claim 3.

Inventors: OBEROI BHUSHAN KUMAR, PALM JEFFERY JAMES, OBEROI, BHUSHAN, KUMAR, PALM, JEFFERY, JAMES
Applicants: OBEROI BHUSHAN KUMAR, PALM JEFFERY JAMES, REDLAND ENG LTD, OBEROI, BHUSHAN, KUMAR, PALM, JEFFERY, JAMES, REDLAND ENGINEERING LIMITED
Application year: 1996
Main classification: B28B11
IPC codes: B28B5, B28B7, B28B11