FR2525519A1 - Method of casting concrete inspection chamber - uses external and internal forms with latter lined by plates which are vibrated and withdrawn during pour - Google Patents

Abstract

The casting process is used to make hollow concrete products, with side walls and a floor. It is for application to the manufacture of inspection chambers. The mould comprises internal (3) and external (2) forms of the appropriate finished profile, the process entailing filling the mould, vibrating, pressing (18) and striking. Measures are taken to promote the flow of concrete between the two forms, i.e. the inner form may be vibrated independently. Plates (11) lining this form may be both vibrated and withdrawn by sliding. Filling may be in two stages, of which the second (15) adds the quantity required in the floor and striking may use a return movement of the side plates to push (22) the product out of the mould.

Description

 The invention is a;, ative to a process for molding hollow concrete products, a junction box obtained according to the molding process for hollow products.

 The invention will particularly find its application in the production of rafts intended for the junction of road pipes.

 Currently, the production of hollow concrete products is obtained by using molds composed of several inserts using quick pins, these molds being filled with concrete by successive shovels. The molds are placed on vibrating tables which, by their oscillating movements, allow certain compaction of the concrete. Then, the product is demolded by removing the quick pins which allows to dismantle the mold enveloping the product.

 The manufacturing process has many drawbacks.

On the one hand, it requires significant handling which results in a high cost price of the product, on the other hand the work of the operators is very painful in particular because of the noise caused by the vibrating table.

 With regard to the current connection boxes, these are generally made of relatively thick concrete walls to provide them with a certain solidity, which results in a high weight. In addition, to facilitate their removal from the mold during their manufacture, they are produced with a relatively large draft angle. This draft has the effect of making the junction boxes not stackable directly, it is necessary to use intermediate pallets. Therefore, in terms of logistics, the presence of these pallets leads to additional costs without providing benefits.

 In addition, currently, the junction boxes have a unique pre-cut of the wall and therefore they can only receive one type of pipes for which they are specific, which requires the manufacture of a wide range.

 The process for molding hollow concrete products according to the present invention comprises the conventional steps in the matter. Either, first of all, the mold is filled, consisting of an outer casing with the shapes of the external contour of the product to be molded, and a core with the shapes of the inner profile of the said product. During this filling operation, the nipple is vibrated simultaneously. Then we press the concrete to make it more compact. Finally, the product is removed from the mold.

 According to the present invention, during the mold filling operation, the flow of concrete in the mold is favored and in particular between the outer envelope of the mold and the inner core.

This action ensures good filling of the mold even when the side walls of the product to be obtained are thin.

 In this way, the product obtained does not contain any surface or internal defect which could affect its mechanical strength.

 In addition, by using an energetic demolding process, it is possible to obtain parts which no longer have the traditional draft. In particular, connection boxes can be obtained according to this process.

 These connection boxes can easily be stacked since they have no undercut, and in addition, will have a relatively low unit weight thanks to their realization in thin walls but highly compact.

 In addition, according to the present invention, the junction boxes have several pre-cuts of the web which allows them to receive either pipes of any diameter by which it will suffice to cut the web appropriately so that the cut performed corresponds to the diameter of the pipeline.

Thus, with a few models of boxes, it is possible to cover multiple applications.

Other advantages of the present invention will become apparent during the description which follows, which is however only given for information and which is not intended to limit it, this description being accompanied by the following drawings, given by way of illustration to illustrate the invention e
- Figure la / n illustrates the different stages of the molding process of a hollow concrete product according to a preferred embodiment of the invention.

 - Figure 2 illustrates a connection box, in partial section, obtained by applying the method of the invention.

 - Figure 3 illustrates the section I-I of the connection box of Figure 2.

 The process of molding ae the invention relates to concrete and equal to other iaaterials uont the implementation is similar.

 The molding process for concrete products according to the present invention is more particularly suitable for hollow products. In fact, this type of product generally has thin walls which are difficult to produce. However, by extension, the molding process for concrete products according to the present invention may also apply to solid products and in particular to solid products having small thicknesses.

 The molding process according to the present invention is more particularly suitable for being carried out automatically, however, it is obvious that it can also be used in semi-automatic or manual mode by triggering or by successively carrying out the various stages of the process.

 FIG. 1a / h illustrates the various stages in carrying out the method according to the invention which takes up the main conventional stages, namely filling the mold, tamping the concrete and demolding.

 Hollow concrete products are defined by side walls placed on a bottom.

 The mold 1 according to the invention comprises an external envelope 2 with the forms of the external contour of the product and in particular with the external forms of the side walls. This mold 1 also comprises a core 3 with the shapes of the internal profile of the product to be molded. To facilitate the filling of the mold 1, the hollow concrete product will be molded upside down, that is to say it will be molded with the bottom facing upwards, which facilitates the filling of the mold.

 The outer envelope 2 of the mold 1 will also be equipped with shapes 4 which make it possible to ensure reservations in the walls of the product to be obtained. These forms 4 are projecting with respect to the outer envelope 2.

The distribution of the concrete 5 will be ensured by means of a hopper 6 which will circulate above the mold 1. The hopper 6 will have a drawer 7 at its lower part through which the concrete will flow
During this filling operation, the mold 1 will be aniline with a vibration movement which will facilitate the introduction of the concrete between the core 3 and the envelope 2. Thus, the flow of the concrete will be favored in particular during the filling of the zones which must form the side walls of the product.

 According to a preferred embodiment of the mold 1, it will be formed in such a way that the vibrations of the casing 2 schematized by the arrows 3 are independent of the vibrations which animate the core 3 and which are schematized by the arrows 9.

 Preferably, the core 3 will consist of an interior volume 10 produced exactly to the dimensions of the internal profile which the molded product must have, and of a side plate 11 which will surround the core 3.

 According to this preferred embodiment, also the side plate will be anirnee of an independent vibration movement 9.

 Figure lb shows schematically the mold filling operation in progress. Still to promote the filling of the mold 1, in addition to the vibration movement 9 which is subjected to the plate 11, it is made equal.lentglisser this plate 11 so that it is retracted in a cut made in mold 1 for this purpose.

 The movement which has the effect of retracting the plate 11 is shown diagrammatically in FIG. 2b by the arrow 12. During its sliding and its vibrations, the plate 1i tends to entrain the concrete 13 which has flowed from the hopper 6 so to fill the parts of the mold with the end pieces to constitute the side walls of the hollow product. According to a preferred embodiment of the plate 11 and of its movement, this plate 11 will retract into the lower part of the mold 1.

 Figure lc shows schematically the end of the first part of the filling. The hopper 6 has distributed a metered quantity of concrete into the mold 1. This quantity corresponds substantially to the quantity necessary for filling the side walls of the hollow product to be molded. At the end of this first part of the filling, the side plate 11 is practically completely retracted. A shoe 14, the movement of which can be associated with that of the hopper 6, then smoothes the upper part of the concrete 13 poured into the mold 1.

 FIG. 1d illustrates the second part of the filling of the mold 1. The hopper 6, or possibly another hopper, in a return operation for example comes to add an additional quantity 15 of concrete to the surface of the mold 1 to complete the first part of the filling. This additional quantity of concrete corresponds substantially to the value necessary to produce the bottom of the hollow concrete product.

 The figure again shows schematically a smoothing operation of the upper part of the poured concrete in the mold 1. This smoothing is for example carried out using a pad 16 which comes to equalize the upper surface 17 of the poured concrete. The movement of the pad 16 can for example be associated with that of the hopper 6.

 Then, when the mold 1 is filled with concrete, we just compact it in the operation illustrated in Figure lf. The upper surface of the concrete 17 poured into the mold 1 is groomed using a press which applies its matrix 18 to the upper surface of the mold 1, the assembly being vibrated.

 Figure 1g illustrates the first part of the release of the hollow product 19. First of all, the protruding shapes 4 are retracted according to the arrows 20 in the mold 1 so as to no longer form protrusions with respect to the surface of the outer envelope 2 so as not to prevent the extraction of the product 19 of mold 1.

 As soon as the forms 4 retracted into the mold 1, the lower part 21 of the molded product is pushed in order to release it from the mold 1. Advantageously, the side plate 11 which had been used to promote filling of the mold can be used for this operation 1. This side plate 11 will be animated with a movement illustrated by the arrow 22 so that it comes out of the cut made in the mold 1.

 FIG. 1h illustrates the release of the product 19 from the mold 1 using the upward movement of the side plate 11 which is applied to the underside 21 of the molded product 19.

 The concrete used for this type of molding will preferably be dry, even very dry so as not to catch the walls of the mold.

 When filling the mold with concrete, a slight excess thickness of concrete will advantageously be distributed. This extra thickness will be absorbed during the pressing and vibrating operation of the concrete illustrated in Figure lf. In this way, it will be obtained a very compact and very resistant concrete even in the case of sparsely thickened walls.

 The shape of the drawer 7 equipping the hopper 6 which will advantageously be placed on a carriage moving to the upper part of the mold 1, will be adapted to the shapes and dimensions of the mold. It will thus be possible, for example, to envisage a distribution of the non-uniform concrete and for example, it will be possible to produce a form of drawer 7 whose flow is greater at the ends of the drawer 7 which are provided for filling the walls sides of the hollow concrete product.

Furthermore, in the drawing of the bottom of the hollow concrete product
to realize, it will be advantageously envisaged to realize this one
curved. Indeed, in this case, the upper part of the core 3 will have a curvature which will facilitate the descent of the concrete into the walls
sides of the mold.

 We can observe that, thanks to the energetic release of the concrete product, it can be advantageously designed without having to provide it with a draft. Indeed, since the release of the product is obtained by exerting an action on the edges of its side walls, the extraction of the product from the mold is forced.

 The use of a side plate 11 thus has a particularly advantageous dual function.

 FIG. 2 illustrates a connection box obtained according to the method of the present invention. The connection box 22 will have walls of relatively small thickness but compact which allows to obtain a final product of low weight.

 The connection box 22 is provided with pre-cut sails 23 which will allow the connection of road pipes for example.

To facilitate the flow of liquid in the connection box 22, the latter advantageously has a bottom provided with a water wire 24.

This water stream is in the form of a concave curvature formed in the bottom of the box 22.

 The upper edges of the walls of the connection box 22 will advantageously be provided with a flange 25 which will make it possible to accommodate a cast iron grid, as is customary with this type of box. However, it will not be necessary to equip the box 22 with the usual metal frame, since this time the highly compacted concrete will be able to directly support the metal grid.

 The precut web 23 will advantageously have several primers, in the chosen case, two primers 26 and 27. These primers 26 and 27 will be circular, and concentric. They are intended to be broken to pass into the cutout formed, the road pipe. Since these pipes can have different diameters, it will be necessary to provide several primer dimensions in order to cut the web 23 to the dimensions of the pipe to be adapted.

 FIG. 3 illustrates the section I-I of the connection box 22, at the level of the web 23. The primers 26 and 27 will be dimensioned -so that they will have an increasing resistance towards the outside of the web 23.

 By adopting a residual thickness of the concrete wall at the level of the primers, decreasing towards the center of the wall. Thus, on site, we will start by breaking the center 28 of the veil easily since the break will be made at the primer 26 which has a thickness e1 less than the thickness e2 of the wall of the product at the primer 27, then if necessary, the veil will again be fractured on the periphery of the primer 26 between this primer 26 and the primer 27 so as to increase the size of the cut to adapt it to that of the pipe to be connected.

 The embodiment and implementation of the invention which have just been described are given for information only and other modes and implementations could have been adopted without departing from the scope thereof. .

Claims (10)

RsE / E: 4DICATIONS  1. A method of molding hollow concrete products generally having side walls and an fcnd, comprising in particular a step of filling the mold (1) consisting of an outer envelope (2) in the shapes of the external contour of the product and of a core (3) with the shapes of the internal profile of the said product with concrete vibrating, a pressing and vibrating concrete step, then a demolding step, characterized in that the flow of concrete is favored during filling between the 'outer shell (2) of the mold and the core (3).  2. Process. molding according to claim 1, characterized in that the core (3) is vibrated independently of the outer casing (2) of the mold (1).  3. Molding method according to claim 2, characterized in that one vibrates a side plate (11) placed around the core (3).  4. A molding method according to claim 3, characterized in that, during the filling operation, the side plate (11) is driven with vibrations, so as to retract it in a cut made in the mold (1) for this purpose.  5. Molding process according to claim 1, characterized in that a first quantity of concrete is deposited in the mold (1) which corresponds substantially to the quantity necessary for filling the side walls of the product to be molded, comes to smooth the upper surface of the deposited concrete, then a second quantity of concrete is redeposited which corresponds to the remaining part to be molded, that is to say substantially the bottom of the product to be molded.  6. Molding method according to claim 1, characterized in that the product is removed from the mold by exerting an action on the edges of its side walls.  7. Molding method according to claim 4, characterized in that the product is removed from the mold by bringing out the side plate (11) of the cutout so as to exert pressure on the edges of the product.  8. Concrete connection box more generally hollow product produced according to the method of claim 1, characterized in that it has at its side walls no draft.  9. Junction box according to claim 8, characterized in that the bottom has a rounded wire (24).  10. Junction box according to claim 8, characterized in that it has at least one veil (23) having a series of primers (26, 27) of increasing resistance towards the outside of the veil (23).