FR2696772A1 - Formwork and its manufacturing process. - Google Patents

Abstract

The invention relates to a shuttering comprising a tubular molding element (1) provided with flat walls which define a prism whose polygonal cross section corresponds to that of the finished product to be molded, and reinforcing elements (4a-4d) which cover the outer faces of said tubular molding element, formwork which is remarkable in that said reinforcing elements (4a-4d) are held tight on the tubular element by helical wrapping of at least one strip (8) of material glued to at least partially on at least one of its faces. The invention also relates to a manufacturing method which recommends straight wrapping with a wide strip or spiral wrapping with a narrow strip, in particular by means of a winding mandrel (5).

Description

Formwork and its manufacturing process.

  Forms used for the fabrication of poured concrete columns or pillars have long been made using elements

in wood and / or metal.

  Another technique has however been devised to produce forms much cheaper, ready to use and usually used only once, which represents on a site of noeux benefits especially given the ease and speed of

Implementation.

  According to the technique described in particular in the French patent

  1513315, much of the paperboard is used.

  US Pat. No. 3,301,926 or the French patent applications

  however, 2606813 and 2616469 also describe a formwork of the same type, that is to say comprising a tubular molding element whose planar walls define a prism with a writable straight section corresponding to the cross-section of the finished product to be molded, a tube of holding a cardboard circular section which circumscribes the outer section of the tubular molding element and wedging elements arranged in the spaces between the outer faces of said

  tubular molding element and the inner face of the holding tube.

  In order to have good resistance, it is obviously desirable

  to design cushioning elements with good resistance to

the compression.

  FR-2628465 has also devised a formwork provided with an outer tube whose section is no longer circular, but which

is a quadrilateral.

  In the aforementioned patents 1513315 and 2628465, it is recommended to fill the free spaces between the tubular molding element and the

  holding tube including polystyrene In US Pat.

  3,301,926, there is described a method of injecting a material

of that type.

  However, these blocking products are very polluting because the formwork, after use, is destroyed by cutting the tube of

maintenance.

  In the aforementioned French applications 2606813 and 2616469, it has been imagined various holds, in particular cardboard, various shapes

(tubes, folded cardboard,).

  However, compared with the aforementioned technique of injection, the spaces between the tubular molding element and the holding tube are not completely filled, so that the element

  tubular molding is not in full support on a homogeneous material

  born. All the aforementioned techniques require the use of a tubular molding element and a cardboard holding tube, between which are disposed said wedging elements, the generally circular holding tube seeming obligatory to ensure a good

  internal compressive strength.

  The inventors had the merit of completely rethinking the technique and making a formwork easy to manufacture and very

  good resistance to internal compression.

  A formwork according to the invention comprises, in known manner, a tubular molding element provided with plane walls which define a prism whose polygonal cross-section corresponds to that of the

  finished product to be molded, and reinforcement elements which

  the outer faces of said tubular molding element and it is remarkable in that said reinforcing elements are kept tight on the tubular element by wrapping at least one strip of material glued at least partially on at least one of its The wrapping can be done in many ways, such as

  it will be specified below about the process.

  In a formwork according to the invention, it is understood that by way of

  port to the prior techniques there is more external support tube. According to a non-mandatory embodiment, the reinforcing elements each have a prismatic shape with a cross section.

  triangle or trapezium whose dimensions of the large base correspond to

  to those of the outer face of the tubular element on which

  it is applied and whose angles at the base are chosen in such a way

  re such that two lateral faces adjacent to two reinforcing elements

  successive are substantially coplanar.

  For trapezoidal reinforcing elements, the outer wrapping will then form a prismatic sheath 2 N faces, N being the number of sides of the polygonal section of the tubular element, without

  count any chamfers on its edges.

  In the case of a tubular element with a polygonal cross-section

  the all angles at the top are equal, it is sufficient that the cross section of the reinforcing elements is in the shape of a triangle or trapezoid

  isosceles with angles at the base equal to 1800 divided by n.

  In particular, in order to provide a non-polluting and recyclable formwork, which offers excellent strength, the tubular molding element is made of cardboard and the reinforcement elements consist of

  by alveolar cardboard whose edges of each cell are

  perpendicular to the flat wall opposite the element

tubular molding.

  If the honeycomb has the advantage of being recyclable

  and has excellent strength, other materials are obviously

perfectly possible.

  The invention also relates to a method of manufacturing such a formwork which is remarkable in that it consists in: a) forming a tubular prismatic molding element, the cross section of which corresponds to that of the finished product to be molded, b) cutting a reinforcing material into several elements each having a face of dimensions similar to the dimensions of one of the main faces of the tubular prismatic molding element, c) arranging the prismatic tubular element on a winding mandrel, d) arranging the reinforcing elements on the corresponding external flat faces of the tubular element, e) banding the assembly using at least one strip that is glued at least partially on the

least one of its faces.

  According to one embodiment, the prismatic tubular element is made from an optionally grooved cardboard plate

  to form edge chamfers and whose face intended to constitute

  to kill the interior of the formwork is treated to make it waterproof According to one embodiment, the wrapping is performed by a straight winding on several turns using at least one strip of cardboard which

  the width corresponds to the length of the set to be wrapped.

  However, according to one variant, the wrapping is effected by means of at least one strip of cardboard of small width relative to the length of the wrapping assembly and which is wound in a helix

by spiraling.

  The last band used for wrapping may also have on at least its outer face a treatment to make it tight to form a last waterproof coating, it may also carry advertising and / or explanatory inscriptions of a

manual.

  Preferably, the reinforcing elements are made from

a honeycomb cardboard plate.

  To design a formwork of the aforementioned type with prismatic reinforcing elements in the shape of a triangle or trapezium, said

  reinforcement elements are cut accordingly from, for example

  ple, of a plate of a suitable material.

  Advantageously, the reinforcing elements are held on the flat outer faces of the tubular element before wrapping,

  by gluing and / or strapping adhesive strips.

  The invention will be well understood and other features

  will appear on reading the description which will follow and which

  Referring to the accompanying drawings, in which: FIGS. 1 and 2 respectively show, in profile and in perspective, a carton plate before folding to make the tubular molding element, FIG. 3 shows in perspective the tubular molding element FIG. 4 shows in profile a pre-cut cellular cardboard plate for forming the reinforcement elements, FIGS. 5, 6 and 7 show three successive manufacturing phases according to a first embodiment, the tubular element being arranged on a mandrel. 8 shows the finished product obtained after the manufacturing phases of FIGS. 5, 6 and 7, FIGS. 9 and 10 correspond to FIGS. 7 and 8 according to FIG.

a second embodiment.

  To manufacture a formwork according to the invention, a prismatic tubular element is first made from a plate 1, by

  example cardboard 3 (Figures 1, 2, 3 and 5).

  In the example shown, the prismatic tubular element 1 produced (FIGS. 3 and 5) has a substantially square-shaped section (the same reference 1 is used to designate indifferently

  the tubular element or plate from which it is made

  than). To do this, the cardboard plate 1 (Figures 1 and 2) is grooved as shown in said figures (by arrows in Figure 1 and dashed in Figure 2), to divide the plate 1 into four main parts 1a to 1d, intended to form the four walls of the prism (Figure 3) after folding along the grooves and

performed.

  In fact, it can be seen in the figures that the grooves, with the exception of an end groove, are double so as to form

  edge chamfers 2 a to 2 d (Figure 3).

  The tubular element 1 is closed for example by means of an adhesive strip 3 (FIG. 4), or any other means, which is disposed here

  longitudinally between a main face la and a chamfer 2 d.

  The tubular prismatic element 1 thus produced must also

  present the desired dimensions for the finished product to be molded.

  An alveolar cardboard plate 4 (FIG. 4) is cut out

  as shown in Figure 4 in several elements such as 4 to 4 f.

  In the example shown, each element 4a to 4f has a prismatic shape trapezoidal section and more particularly isosceles trapezoidal shape whose corners of the large base are Moreover, the large bases of each trapezoidal prismatic element have dimensions corresponding to those of the faces Ia to Id of the tubular element 1 It will be understood that cutting as shown in FIG. 4 (at 450 in an alternating manner) makes it possible to considerably limit the falls, which constitutes a technique

particularly economical.

  Finally, the face of the plate 1 intended to form the inner surface

  said tubular element is treated to be sealed.

  The tubular prismatic element 1 is then disposed on a

  mandrel 5 (FIG. 5) whose section corresponds to the interior section

  said element 1 (including chamfers), the latter being closed longitudinally

  tudinalement by the band adhévise 3 before or after its establishment

on said mandrel 5.

  As shown in Figures 5, 6, 7 and 9, the mandrel 5 is expandable using, for example, shells 6 to 6 d (Figure 5)

  able to deviate from the axis of said mandrel by any hydraulic means

  than and / or pneumatic and / or mechanical.

  After placing the tubular element on the mandrel, positioning the reinforcing elements 4 a to 4 d, as shown in FIG. 6, by applying the large bases of said elements to the

faces of element 1.

  As is well shown in FIGS. 6 to 10, the dimensions of said reinforcing elements 4 a to 4 d are such (base angles of) that two lateral faces adjacent to two reinforcing elements

  successive are substantially coplanar.

  The reinforcing elements 4a to 4d are held by bonding their faces which are in contact with the tubular element 1 and / or by strapping by means of adhesive strips such as 7a to 7d on the

Figures 6, 7 and 9.

  The next step is to perform a wrapping as

show it in figures 7 and 9.

  The assembly shown in FIG. 6 is streamlined by driving the mandrel 5 in rotation and by winding at least one strip of cardboard 8, 8 '. In FIG. 7, there is shown a wrapping of a strip 8

  by spiraling, that is to say by helical winding.

  The spiraling is advantageously carried out in several layers and possibly in crossed layers by means of at least one band glued at least in part on at least one of its faces (or both its faces) In this case, the strip 8 used obviously presents a

  relatively small width compared to the semi-finished product.

  However, as can be seen in Figure 9,

  kill a right winding of at least one 8 'band wound on several

  turns, said strip then having a width corresponding to the

length of the semi-finished product.

  This produces a finished product (after removal of the mandrel)

  as shown in FIGS. 8 and 10, i.e.

  rolage forms an outer sheath shaped here octagon (regular or

  not according to the thickness chosen for the reinforcing elements).

  However, it is clear that the reinforcing elements could have triangular shapes, the resulting sheath being

then of section also in square.

  In addition, if the tubular element 1 here has a section

  square, this is a special case of a rectangular section

  gular and in a more general way, said section is polygonal,

regular or not.

  If the section of the tubular molding element can thus be generalized, that of the reinforcing elements may be other than trapezoidal or triangular, such as circular segment. In addition, he is not obliged that the neighboring side faces

  reinforcement elements are coplanar.

  Finally, of course, finishes can and / or must be

  made, like a last waterproof wrapping band (possibly

  on a single turn for a straight winding and on a single fold for spiraling), a sealing treatment of the ends, impressions on the outer face of the last band, etc. Such a formwork makes it possible, surprisingly, to withstand high stresses, which is obviously desired for the molding of

concrete posts or pillars.

Claims (11)

  1) Formwork comprising a tubular molding element (1) provided with flat walls (la-Id) which define a prism whose polygonal cross-section corresponds to that of the finished product to be molded, and reinforcing elements (4 a-4 d ) which cover the external faces of said tubular molding element, characterized in that   said reinforcing elements (4 a-4 d) are held tight on the element   tubular wound by helical wrapping of at least one strip (8,8 ') of material glued at least partially on at least one of its faces. 2) Formwork according to claim 1, characterized in that the reinforcing elements each have a prismatic shape with triangular or trapezoid-shaped section whose dimensions of the large base correspond to those of the outer face (la-ld) of the tubular element (1) to which it is applied and whose   angles at the base are chosen in such a way that two lateral faces   the neighbors of two successive reinforcing elements are substantially coplanar.   3) Formwork according to one of claims 1 and 2, characterized   in that the tubular element (1) for molding is made of cardboard and in that the reinforcing elements (4 a-4 d) consist of cardboard   alveolar whose edges of each cell are arranged perpendicular   the plane wall facing the tubular element   ge. 4) A method of manufacturing a cardboard form, characterized in that it consists in: a) forming a tubular prismatic element (1) of molding, whose cross section corresponds to that of the finished product to be molded, b) cutting a reinforcing material (4) made of several elements (4 a-4 d) each having a face of dimensions similar to the dimensions of one of the main faces of the prismatic tubular element (1) of molding, c) arranging the prismatic tubular element (1) on a winding mandrel (5), d) arranging the reinforcing elements (4 a-4 d) on the corresponding external flat faces of the tubular element, e) wrapping the winding mandrel (5) together using at least one strip (8,8 ') which is glued at least partially on at least one of its faces.   5) Method according to claim 4, characterized in that the prismatic tubular element is made from a cardboard plate (1) optionally grooved to form edge chamfers and whose face intended to constitute the interior of the formwork is treated to make it waterproof.   6) Method according to one of claims 4 and 5, characterized   in that the wrapping is carried out by a right winding on several turns of at least one strip (8) of cardboard whose width   corresponds to the length of the set to be wrapped.   7) Method according to one of claims 4 and 5, characterized   in that the wrapping is carried out by means of at least one strip of cardboard (8) of small width relative to the length of the assembly to   banding and which is spirally wound spiraling.   8) Method according to one of claims 4 to 7, characterized   in that the last band used for the wrapping has on at least its outer face a treatment to make it waterproof so that   to form a last waterproof coating.   9) Method according to one of claims 4 to 8, characterized   in that the reinforcing elements (4 a-4 d) are made from a plate (4) of cellular cardboard.   10) Method according to one of claims 4 to 9, characterized   in that the reinforcing elements (4 a-4 d) are cut so as to each have a prismatic shape with a triangular or trapezoid cross-section whose dimensions of the large base correspond to those of the outer face (la-ld ) of the tubular element (1) to which it is applied and whose corners at the base are chosen so that two lateral faces adjacent two elements of   successive reinforcement are substantially coplanar.   11) Method according to one of claims 4 to 10, characterized   in that the reinforcing elements (4 a-4 d) are held on the faces   external planes (la-ld) of the tubular element (1) before a banderola-   age, by gluing and / or strapping adhesive strips (7 a-7 d).