Static molds – In situ construction engineering type or building type-mold... – Forming building structure
Reexamination Certificate
1999-10-13
2001-07-17
Safavi, Michael (Department: 3635)
Static molds
In situ construction engineering type or building type-mold...
Forming building structure
C249S051000
Reexamination Certificate
active
06260816
ABSTRACT:
OBJECT OF THE INVENTION
The present invention relates to a new disposable formwork for the obtention of columns, for example made out of reinforced concrete, said formwork having an optimum performance based on a simple and therefore economical structure.
Furthermore, it is possible to obtain with this formwork a perfect superficial finish of the columns, which makes it equally usable for the obtention of columns to be covered and for columns which surface will be seen and therefore require an optimum superficial finish.
BACKGROUND OF THE INVENTION
It is evident that, to build a column made of, for example, reinforced concrete, a mould or formwork is needed to provide the column with its configuration and dimensions, said formwork requiring two different and complementary features: on the one hand it has to ensure a perfect superficial finish of the columns and on the other hand, especially when the formwork is disposable, its cost has to be sufficiently low to make it profitable for the builder.
In the field of disposable formworks for the manufacture of cylindrical columns, formworks are known based on a tubular body, made of paperboard, with its internal side covered by a waterproof liner thus avoiding the deterioration of the paperboard due to the humidity generated from the concrete, said liner being obtained from an aluminium complex. The tubular body has, additionally, another external liner, generally plasticised, to protect likewise the paperboard and to mark the product externally.
For the manufacture of columns with polygonal section, for example columns with a square section, polystyrene plates duly configured to be adapted externally to the cylindrical wall of the tube and to form, as a whole, the desired polygonal section of the column, are established and attached conveniently inside said tubular body.
The above-mentioned solutions, although they are functionally valid, are structurally complex and economically expensive. They present, furthermore, some limitations regarding the possibilities to design certain types of columns due to the fact that the filling plates have to be introduced and to be attached inside the tubular pre-existing body.
DESCRIPTION OF THE INVENTION
The disposable formwork for columns proposed by this invention solves the problems mentioned above in a completely satisfactory way.
To achieve this, in particular, said formwork comprises a tubular body, made of polystyrene or a similar material, based on a plurality of intercoupling pieces or plates defining an internal hollow space, the form and dimensions of which coincide with those of the column to be obtained, and an external preferably cylindrical surface, that could also adopt similarly a polygonal configuration, with the particularity that it has, attached with adhesive to the inner side of said tubular body, a plastic sheet, for example made of PVC or the like, closed over itself by any conventional means, to configure also a tubular body having a sealed surface; on the outer side, the formwork comprises a reticulated support, made of a glass fibre mesh, that rolls up helicoidally on the tubular body defined by the polystyrene parts to which it is attached with adhesive as well.
As a complement of the described structure, the formwork may comprise externally, i.e., outside the mesh, a sealing band, also rolled up helicoidally on the formwork, totally covering the surface of the mesh or, if rolled with a bigger pitch, leaving part of the mesh visible; said sealing band has mainly a decorative function and can serve as product advertising support.
When due to the manufacturing conditions, the correspondent column must present a perfectly smooth surface, the above solution may be inadequate because in the plastic sheet made of PVC or the like, which constitutes the inner operative surface of the formwork, they often appear small wrinkles that are transmitted then to the concrete mass forming the column, causing superficial irregularities; this is why it has been foreseen to substitute said inner plastic sheet of PVC or the like by plates of reduced thickness, with the same amount and dimensions as the sides or plans of the column to be obtained.
Said plates of reduced thickness may be made of plasticised wood, like MDF, or they may consist of rigid plastic plates.
Said plates are attached to each other to configure the required tubular body, with the help of adhesive tapes fixed to what will become their inner side; in the case of wooden plates being used, said adhesive tapes have the complementary purpose of sealing the tubular body, thus preventing the water from the concrete to penetrate through the edges of the wooden plates, said plates edges being obviously not plasticised in order to allow the use of commercial panels.
In case of rigid plastic plates being used, where the adhesive tapes do not have a sealing function, said tapes can be located on the external side of the tubular body for the purpose of avoiding any marks, despite their reduced thickness, on the surface of the column.
According to another feature of the invention it is provided, for the manufacture of polygonal columns with bevelled edges, instead of the plasticised wooden strips or the plastic strips corresponding to said bevelled edges, plastics profiles are used which determine the plan that corresponds to said faces and, additionally, said profiles comprise lateral grooves properly oriented and dimensioned to allow the engagement of the plates, made of wood or plastic and corresponding to the main lateral walls of the column; said grooves present their open side sufficiently throttled as to allow the engagement of said plates under pressure and in a completely watertight manner concerning the edges of said plates.
According to the above, not only a perfect superficial finish of the column to be obtained is achieved but furthermore the whole set can be easily disassembled and reused because the inner liner is not glued to the polystyrene, which has an ecological impact.
However it may be desirable that the surface of the column to be obtained, instead of being completely smooth, presents some relief simulating streaks and knots of the wood, as when a conventional formwork based on conveniently intercoupled wooden panels is used to define a cylindrical receptacle; in this case, and according to another feature of the invention, it is provided the use of strips of noble wood, waxed on their inner side to facilitate the removal of the formwork, attached with glue to the tubular body of polystyrene, before the definitive attachment of the parts constituting the same, preferably when the body is build in two halves that will finally be closed one on each other after said noble wooden strips have been fixed to them by means of an adhesive.
In any case, and in the same way as foreseen in the main patent, the tubular polystyrene body, properly closed and wearing on its interior side the liner made of plasticised wooden plates, plastic plates or noble wooden strips, is externally surrounded by the grid made of fibre glass mesh, forming a continues band rolled up helicoidally, and being optionally assisted by said sealing band.
Finally and according to another feature of the invention, in case of columns with polygonal cross-section, for example square or rectangular section, it is foreseen the location of seals acting as a signalling system at the ends of the formwork, in a position that corresponds to the edges of the column, to facilitate the mounting of said formwork during the building works in the correct position.
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patent
Safavi Michael
Young & Thompson
LandOfFree
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