Collapsible form and device for removing form from cast concrete

Details Collapsible form and device for removing form from cast concrete Collapsible form and device for removing form from cast concrete

1985-08-29

1987-05-19

Woo, Jay H.

Plastic article or earthenware shaping or treating: apparatus

With transportation device for relocating molding apparatus...

249 39, 249 66R, 425438, 425440, B28B 730, B28B 1304

Patent

active

046663886

DESCRIPTION:

BRIEF SUMMARY
The invention relates to a method of making openings, such as those for a window or door or the like when casting a concrete structure, e.g. a cast-in-situ wall, by utilizing a rigid, reusable form made from a frame with a smooth exterior surface. The method involves the form being loosened from the cast concrete structure and being taken out of the opening formed by it. By "rigid form" is intended that the form is rigid during use but may be dismantled, e.g. for storage.
The apparatus for carrying out the method includes a re-usable form made from bar sections, and means for removing the form from the opening formed during casting.
The Swedish patent application No. 84 00480-3 describes a method and apparatus of the kind mentioned above. A certain disadvantage with the technique known from this patent application is that the form must be relieved, i.e. its walls must be slightly sloping to allow it to be removed from the cast wall opening with the aid of the removal means described in the patent application. The form binds very solidly in the opening and large force is required to remove it. This may result in that the form and/or the concrete surface may be damaged if circumstances are unfavourable.
The present invention is directed to providing a method and apparatus of the kind described in the introduction, with the aid of which the form may be easily released from the cast opening without being subjected to impermissibly large forces. Furthermore, the form does not need to have relief, which makes it possible to have the opening square to the cast wall, i.e. without the slightly tapering shape. The characterizing features of the invention are apparent from the accompanying claims. The French patent No. 2,176,167 describes an apparatus intended to be used in casting heavily tapering concrete blocks without demands on dimensional accuracy and surface finish. The blocks are cast in a square form, the walls of which incline towards each other, i.e. the form is pyramidal. The form is released with the aid of gripping claws, using a jack which bears against the ready concrete block, to pull the form away from it. The pulling forces are directed substantially parallel to the chief plane of the form. It will be understood that the necessary pulling forces are considerable, in spite of the form having relief.
The invention will now be described in detail with reference to the accompanying drawings, on which
FIG. 1 is a perspective view of the form in accordance with the invention
FIG. 2 is a perspective view of the stand for releasing the form
FIG. 3 illustrates the stand in position for loosening the form
FIG. 4 is a perspective view of a detail in the stand
FIG. 5 is a perspective view of two levers included in the form in FIG. 1, seen from one side
FIG. 6 is a perspective view of the same levers seen from the other side
FIG. 7 is a perspective view of the levers in FIGS. 5 and 6, mounted on the end of their repective tension bars and
FIG. 8 is a side view of the upper holder for the tension bar illustrated in FIG. 7.
FIG. 1 illustrates a form intended for making a window opening in a cast wall. Before casting the wall the form is placed at the desired height with the plane surface facing away from the observer in contact with an unillustrated shuttering wall forming the outside of the finished wall. After a suitable number of forms in accordance with the invention have been placed against the unillustrated shuttering wall, a shuttering wall, forming the inside of the finished wall is placed into contact with the chief plane facing towards the observer of the forms in accordance with the invention, and concrete is poured in between the shattering. After striking the unillustrated shuttering, the forms in accordande with the invention are thus cast into the wall and the technical task to be solved by the invention is now to remove the forms from the openings without damaging the forms or the concrete surface. To do this it should not be necessary to dismantle the form, so that after it has been taken out of

REFERENCES:
patent: 2557631 (1951-06-01), Callan
patent: 3827840 (1974-08-01), Kistler
patent: 4078759 (1978-03-01), Lanier

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