Plastic and nonmetallic article shaping or treating: processes – With severing – removing material from preform mechanically,... – Forming continuous work followed by cutting
Patent
1998-05-21
2000-06-06
Aftergut, Karen
Plastic and nonmetallic article shaping or treating: processes
With severing, removing material from preform mechanically,...
Forming continuous work followed by cutting
264148, 264161, 264163, B28B 714, B28B 1116
Patent
active
060714484
DESCRIPTION:
BRIEF SUMMARY
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 of the 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.
In addition, because the knife of the 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 operations 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 of the objects of the 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: mortar; pallets to form a continuous ribbon of mortar thereon; and, thereby severs the ribbon of mortar at the joints between successive pallets of the series of pallets; 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 cu
REFERENCES:
patent: 4695418 (1987-09-01), Baker et al.
patent: 4856395 (1989-08-01), Smith et al.
patent: 5108679 (1992-04-01), Rirsch et al.
patent: 5223200 (1993-06-01), Schulz et al.
Oberoi Bhushan Kumar
Palm Jeffery James
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