CS242477B1 - Extendable retractable core for forming cavities in betftne - Google Patents

Abstract

The retractable core is designed to create cavities in concrete during its production and allows its demoulding after the concrete has cured. By applying force to the longitudinal beam of the core, which pulls the core out of the concrete, tensile forces are also created in the pullers, which attach the core shell to the beam with joints. Elastic inserts between the shell parts, or deformable walls, allow the outer circumference of the shell to be pulled, which releases it in the concrete and pushes it out of the concrete.

Description

SUMMARY OF THE INVENTION The present invention provides a retractable core for forming cavities in concrete for use in both monolithic concrete and prefabricated fabrication. '·'

So far, there are several ways of creating cavities in concrete, either with solid cores, sometimes with converging walls, drawn! from ripened concrete, or using disassembled cores, possibly non-ripples with high wall conicity, selected from ripened concrete.

Also known are interior formwork and cavity cores, the walls of which form flat surfaces, and the formwork walls are deliberately deformed by complicated manual or hydraulic pullers. The classic way is simple dismantling for one or more uses. Inflatable formwork is used mainly for circular cross sections. ----> ......

These are devices for forming cavities in ripened concrete, the drawback of which is the low strength of the molded ripening concrete, the formation of cracks caused by the movement of the core and, in the case of its conicity, the convergence of the walls of the formed cavity. Demountable, possibly partial demountable cores and formwork, selected from mature-concrete, are labor intensive and maintenance-intensive and unsuitable for continuously operating technology systems. Their r-ealization is less difficult with smaller cavity cross-sections.

Systems varying the cross-section of the sheath deformation into the interior of the cavity are suitable only for straight or shear. inwardly folded walls and not at all suitable for walls bent outwards, such as in circular and similar cavity cross-sections.

The above drawbacks are eliminated by the pull-out pulling core, the principle of which, when vacuuming it from the concrete, a portion of the pulling force is transferred to the core shell by means of pull rods and is used to reduce the core cross section to release it in the concrete and the core moves. The core retraction allows flexible backing inserts in its outer shell.

By removing the core, it is released in the hardened concrete, clean only by the force of the pull-out force without the need to dismantle or release some parts of the core, resulting in the possibility of making smaller cross-section cores and inferior parts than the current systems do, at a warm resistance to external pressures with the ability to compact the concrete mix by vibrating the core.

To accelerate the solidification of the concrete, the heat core can be heated. The individual cores can easily be joined together, even during the concrete product forming process. It does not matter whether the core is pulled or printed. The economic benefits of the core include the reduction of the labor intensity of its technological use against current systems.

In the accompanying drawing in Fig. 1, there is shown a core consisting of two parts for forming a circular cavity in concrete in the concrete, Fig. 2 illustrates the core when being ejected from the concrete, in this case acting as a pulling pull force "P", Figures 3, 4, 5 and 6 illustrate examples of cores for non-circular cross-sections.

The core shell 1 of FIG. 1 consists of longitudinal rigid shell parts 8 joined together by an elastic insert 2, which may advantageously form part seals simultaneously. The parts are connected to the beam 3 by means of the rods 4 fixed in the hollow shell parts 5 and the beams 6 of the beam. When the axial force "P" is applied to the beam 3 of Fig. 2, the rods 4 deflect the angle α, which is enabled by the simultaneous compression of the elastic inserts 2 by the forces generated by the rods.

Finally, the reduction of the core cross section is proportional to the resistance that the core places against the protrusion. FIG. 1 and 2 also show an example of connecting multiple cores.

FIG. 3 shows a non-circular cross-section of the core formed of rigid skin panels 8 and a resilient deformable wall 7. The core retraction is achieved by compressing the elastic inserts. 2 between the rigid shell parts 8 and the elastic deformation of the deformable walls 7. In Figure 4 the core is in a contracted state. Figure 5 is an example of a core whose housing consists only of resilient deformable walls 7. In Figure 6, its cross-section is shown in a contracted state. FIG. 3 to 6 are examples for forming a non-circular core.

The utility of the invention is very broad. It can be used to make cavities, holes and guides in monolithic concrete structures, but also in prefabricated fabrication.

Claims (2)

SUBJECT A retractable contractile core for forming cavities in concrete, characterized in that it consists of an outer shell (1) connected to a longitudinal beam (3j) by means of rods (4J fixed in the joints [5] of the shell (1) and joints (6j of the beam) ). 2. Retractable downloadable core according to INVENTION according to claim 1, characterized in that the core sheath (1) is, according to the cross-sectional shape, formed by joining the rigid sheathing elements (8j by means of elastic inserts (2), or from flexible demouldable walls (7j and combinations thereof).