EP0191652A1 - Method for making a block of concrete with an insert, and mould for performing the method - Google Patents

Abstract

1. Method for producing a concrete block comprising an insert (20) consisting in using first (12) and second (14) mold shells which have complementary cavities (16, 18) representing the final shape of said block, said mold shells comprising recesses (28, 30, 32, 29, 31, 33) designed to receive those parts of the insert which are intended to project from the concrete block, said mold shells being so produced as to exhibit at least a superficial elasticity and to apply closely and under pressure against those parts of the insert which are received in said recesses, characterized in that at least one of the mold shells is produced by molding polystyrene foam, wherefrom said shell inherently exhibits said superficial elasticity, and in that a protective film is applied inside the mold cavities, and before casting the concrete, said film forming a supple pouch in plastic material equipped on the inside with anchoring lugs.

Description

The present invention relates to a method for manufacturing a concrete block comprising an insert, and a mold for implementing the method.

It has recently been imagined to replace the simple blocks of concrete which serve as ballast in domestic washing machines with concrete blocks overmolded on a metal insert, which brings many advantages, in particular with regard to the mounting and fixing of the ballasts, the dimensioning of their supports, the size of the ballast / support assembly, the protection of the support against corrosion, the quality of the sealing of the insert in the concrete, etc ...

Given the small space available around the tank of the washing machine, these blocks generally have relatively complicated shapes, which results in a corresponding complication in the manufacturing molds.

These molds are therefore necessarily particularly expensive, especially since they undergo severe abrasion on the part of the components of the concrete and it is advisable to replace them at regular intervals.

On the other hand, each time we want to change the shape of the block, it is necessary to make new molds, at the expense of cost.

When making the mold shells, it is also necessary to carefully define their connection surfaces, otherwise called "joint planes", which is particularly delicate in certain cases.

Furthermore, in the case of concrete blocks overmolded on metal inserts, there is also a thorny problem, which is to make available to the constructor-assembler of the machine blocks in which all of the insert parts external to the concrete are absolutely free of traces of concrete, on the one hand because these parts of insert include fixing means, such as for example threads or threads, or even lugs or positioning surfaces, and secondly because the end customers (consumers) or intermediaries (wholesalers, resellers) would not admit the presence of such traces of concrete on certain components of the machine in the vicinity of other components whose appearance is impeccable.

It is of course possible to clean the exterior parts of the insert after making the concrete block, but at the expense of cost. Alternatively, one can also deposit a localized protective coating on the insert, such as peelable coating, which is then removed, the traces of concrete disappearing in the same operation, but here too these operations represent an additional cost.

Finally, there is also the obligation to clean the mold and grease it before reuse after making each block so that they present, for the reasons already mentioned, an impeccable external appearance and are free of small non-agglomerated particles on the surface and generating dust.

In order to overcome these drawbacks, the present invention provides a method of manufacturing a concrete block comprising an insert, characterized in that a first and a second mold shells having cavities complementary to the final shape are used. of said block, said mold shells comprising reservations intended to receive those of the insert parts which must protrude from the concrete block, said mold shells being made of a material having an elasticity at least superficial so as to be applied intimately and under pressure constraint against the insert parts received in said reservations.

Thanks to these provisions, the insert parts external to the block are tightly trapped between the two mold shells in the reservations provided for this purpose and no trace of concrete can infiltrate between the mold shells and the insert. level there.

According to an advantageous arrangement of the invention, the mold shells are themselves produced by molding in expanded plastic material, so as to be used for a single molding and to serve as a lost packaging for the transport and handling of blocks.

The application of the invention is not limited to the production of ballast blocks for washing machines, but meets many perspectives, such as, for example, the production of conveyor rollers, and as a general rule all the applications where it is desired overmoulding a concrete block around a metallic or non-metallic insert, avoiding the formation of traces of concrete on the projecting parts of the insert.

• la figure 1 est une vue en perspective éclatée d'un moule destiné à la mise en oeuvre du procédé selon l'invention;
• la figure 2 est une vue en coupe transversale du moule de la figure 1 en condition assemblée;
• la figure 3 est une vue en bout du moule de la figure 1;
• la figure 4 est une vue schématique de dessus d'une machine de moulage; et
• la figure 5 est une vue en coupe illustrant une variante de l'invention.

The various details and advantages of the invention will appear clearly on reading the description which follows, with reference to the appended drawings, in which:

• Figure 1 is an exploded perspective view of a mold for the implementation of the method according to the invention;
• Figure 2 is a cross-sectional view of the mold of Figure 1 in assembled condition;
• Figure 3 is an end view of the mold of Figure 1;
• Figure 4 is a schematic top view of a molding machine; and
• Figure 5 is a sectional view illustrating a variant of the invention.

The mold designated as a whole by the reference 10 consists of two shells, respectively lower 12 and upper 14, in which are formed cavities 16, 18 which, once the two shells assembled, have a shape complementary to that of the block of concrete to be made.

In the example illustrated, the block in question has a U shape and includes a metal insert 20, schematically in this example having the shape of a bar, which is partially embedded in the two branches of the block, the middle part 22 of the insert crossing the space between the two branches and two ends 24, 26 projecting on either side of the branches of the block.

To avoid the appearance of traces of concrete on the parts of the insert which are located outside the concrete, provision has been made in the shells for reservations 28, 30, 32 to receive the insert, and the shells are made of a material which has a certain elasticity, at least superficially, so that the insert is applied intimately and under pressure stress in the reservations.

A preferred material having such characteristics is expanded polystyrene, for example having a density of 22 kg _{/ m} 3.

For a good maintenance of the insert, the dimensions of the reservations are chosen slightly smaller than the dimensions of the insert, so that the latter is placed in the reservations under slight constraint, which is known as " with greasy fitting ".

Thanks to these provisions, a correct positioning of the insert is obtained in the mold shells, and this regardless of the dimensional variations of the insert due to tolerances during its manufacture.

If necessary, the insert can be heated beforehand to facilitate its placement in reservations.

As can be seen in the figures, the reservations in the lower shell have the form of recesses, while in the upper shell, they have the form of projections of complementary profile 29, 31, 33, and it will be understood that the term "reservations" chosen in the present description has a conventional character.

The two shells also include relative positioning means, such as holes 34 in the lower shell, and pins 36 in the upper shell, but any other suitable arrangement may be chosen in this regard.

The upper shell finally has an orifice 38 for pouring the concrete towards the interior of the mold cavity.

FIG. 4 to which we now refer, schematically illustrates in plan an automatic machine 100 for the production of concrete blocks according to the method of the invention.

The machine comprises a rotary table with six stations and we will describe its operation station by station.

At the first station 101, the lower shell 12 is placed, manually or with the aid of an automaton, on a support.

At the second station 102, the insert 20 is placed in the reservations of the lower shell, here also manually or automatically.

At the third station 103, the upper shell 14 is put in place on the lower shell-insert assembly. Preferably, the two shells assembled under a certain tightening are maintained, from this station and until the last station, for example by means of pressure clamps 110 secured to the table 112 of the machine.

In the fourth station, a metered quantity of liquid concrete preparation is poured into the interior of the mold through the orifice 38, by gravity, from a hopper 114. In addition, this quantity of concrete is weighed with precision.

In the fifth station, the concrete is vibrated using a vibrating device shown diagrammatically at 116 so that it is applied perfectly against all the surfaces of the mold cavity, as well as on the submerged parts of 1 ' insert, and that all the air pockets are absorbed, the air escaping through the orifice 38. At this same station, various controls are carried out (weight, dosage, composition, etc.) by means of '' schematized in 118.

Advantageously, provision may also be made to inspect the block by radiography in order to verify that the entire mold cavity is well filled with concrete and / or that there are no air pockets within the concrete.

Finally, at the sixth and last station 106, the mold is released from the table 112 and it is evacuated on an evacuation plan 120. Of course, a quick-setting concrete composition is chosen so that the setting of the concrete is essentially completed. at this moment.

It is easy to understand that during the whole phase of filling, vibrating and setting the concrete, the two shells are applied intimately against each other, as well as against the external parts of the insert, so that there can be no traces of cement on the parts in question .

Thanks to the preferred choice of expanded polystyrene for making the mold shells, these are used for a single molding and are then used as protective packaging for the block-insert assembly during transport and subsequent handling. It was even surprising to note that this material allowed an exellent vibration of the concrete, which one could doubt a priori insofar as its preferred applications to packaging result from its properties of absorption of shocks and vibrations.

This use in single molding makes it possible to no longer take account of the progressive wear of the mold and of its replacement at regular intervals, problems which are encountered in conventional molds.

Another advantage of using expanded polystyrene is that there is great latitude in defining the joint planes between the two mold shells, these planes therefore being able to be as complex as necessary.

Of course, the shells are themselves produced by molding, but it will easily be understood that the primary mold used for this purpose is subjected to negligible wear.

In addition, if it is necessary to make dimensional modifications to the concrete blocks, it will also be particularly easy to modify the primary mold accordingly by adding and / or removing material at the locations concerned, without this resulting in significant costs.

Advantageously, provision will be made for the possibility of producing a whole range of different blocks using the same automatic machine, by imposing an identical external shape for all the mold shells corresponding to the different blocks.

In this regard, it should be noted that the ballasting of washing machines is almost always ensured by two or three blocks different, which can therefore be performed on the same machine, practically without interruption from one series to another.

Various variants can be envisaged, from the above description.

Firstly, for the material constituting the mold shells, it will be possible to choose different materials, in expanded form or in dense form, such as for example resins reinforced or not with glass fibers deposited by application or projection onto a form reproducing the shape of the block to be produced.

Secondly, an interior lining of the mold can be provided before pouring the concrete, this lining remaining integral with the block after demolding and forming a protective envelope. This solution is advantageous when one fears the disintegration of the block on the surface, when one wishes to give it a particular external appearance, such as for example a chosen color, or even if one wishes to reveal particular patterns, for example inscriptions technical or advertising.

This protective lining can be produced in situ by spraying a resin inside the mold, or can also be in the form of a preformed pocket made of flexible plastic.

To favor its attachment to concrete, such a pocket will preferably have regularly spaced interior projecting lugs.

Finally, provision may be made to make the two mold shells from different materials, for example a lower shell of expanded polystyrene serving for a single molding and forming a lost package for transport and handling, while the upper shell is made of a resistant material. more rigid and is reused for a series of moldings, providing of course for cleaning at regular intervals.

This solution will be advantageous in the case of concrete prepared with a certain amount of water. Indeed, the drying of the concrete can be carried out freely by the upper face of the block. Preferably, the shape of the lower shell will be modified by so as to allow stacking of several blocks.

In Figure 5, there is illustrated the production of a completely different product using the method according to the invention. This involves manufacturing cylindrical rollers for conveyors, the outer sleeve of which is made of concrete.

In this case, the insert 200 consists of a metal pin 202 carrying two bearings 204 flanked by protective cups 206, and an inner filling sleeve 208 extending between the cups 206. For casting the outer sleeve in concrete 210, two mold shells are used, the lower shell 12 having essentially the form of a closed tube, and the upper shell 14 having the form of a closure cap for the mouth of the tube.

The reservations are constituted here by annular shoulders 212, 214 against which the external edges of the cups 206 are pressed.

The centering of the axis is ensured by holes 216, 218 in the two shells.

As in the previous case, the filling with liquid concrete is carried out via an orifice 220 of the upper shell.

Claims (16)

1. Method for manufacturing a concrete block comprising an insert (20), characterized in that a first (12) and a second (14) mold shells having cavities (16, 18) complementary to the final shape of said block, said mold shells comprising reservations (28, 30, 32, 29, 31, 33) intended to receive that of the insert parts which must protrude from the concrete block, said mold shells being produced in a material having an elasticity at least superficial so as to apply intimately and under pressure stress against the insert parts received in said reservations. 2. Method according to claim 1, characterized in that one of the mold shells (14) has an opening (38) for the gravity casting of the preparation of liquid concrete and the evacuation of air from the cavity during filling. 3. Method according to one of claims 1 to 3, characterized in that one performs a vibration operation of the concrete after casting. 4. Method according to any one of claims 1 to 3, characterized in that the mold shells are made by molding in expanded plastic. 5. Method according to claim 4, characterized in that said plastic material is polystyrene. 6. Method according to any one of claims 1 to 3, characterized in that said mold shells are made of synthetic resin reinforced with glass fibers. 7. Method according to claim 6, characterized in that said mold shells are produced by applying the resin and glass fibers on a form. 8. Method according to any one of claims 1 to 7, characterized in that one applies to the interior of the mold cavities, and before pouring the concrete, a protective film. 9. Method according to claim 8, characterized in that said protective film has the shape of a flexible pocket in plastic material. 10. Method according to claim 8 or 9, characterized in that said protective film is provided with internal anchoring lugs. 11. Method according to any one of claims 1 to 10, characterized in that two shells of different materials are used. 12. Method according to claim 11, characterized in that one of the shells is made of expanded polystyrene and intended for a single molding then for the transport and handling of the blocks, while the second shell is made of resistant material and reused for several moldings. 13. Mold for manufacturing a concrete block comprising an insert (20), according to the method of one of claims 1 to 12, characterized in that it is composed of two mold shells (12, 14) having cavities (16, 18) complementary to the final shape of said block, and reservations (28, 30, 32, 29, 31, 33) intended to receive those of the parts of the insert which must protrude from the block, the shells being made of a synthetic material having an elasticity at least superficial. 14. Mold according to claim 13, characterized in that said shells are made of expanded plastic, by molding. 15. Mold according to claim 14, characterized in that said plastic material is polystyrene.

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