EP0117184A1 - Openwork structure in expanded material, filter and heat exchanger including such a structure - Google Patents

Abstract

The invention relates to an openwork structure of expanded material, comprising at least one solid strip (4) parallel to the direction of deployment. Said strip has, in the direction of deployment, a length less than that of the deployed part.

Description

The present invention relates to an openwork structure in expanded material and more particularly such a structure comprising at least one solid strip parallel to the direction of deployment, made of any suitable material such as metal, paper, synthetic material or fabric.

We already know such openwork structures in which a metal sheet is split leaving each of its sides in the direction of deployment a solid strip and then is stretched, which has the effect of deploying the split part, while laminating the solid strips to increase their length. The solid strips are thus brought to the same length as the deployed part of the perforated structure, the assembly being in the form of a structure deployed in certain zones and full in other zones.

Such a structure has, however, in certain applications, such as for example in the production of filters, the drawback of requiring relatively large external dimensions for a given surface of expanded metal and therefore of filtering, due to the rolling of the lateral strips.

In addition, its manufacture is relatively complex since, on the one hand, it takes place in two operations and that, on the other hand, the second operation requires a rolling of the lateral strips of the material.

The present invention aims to overcome these drawbacks and has for this purpose an openwork structure of expanded material comprising at least one solid strip parallel to the direction of deployment, characterized in that said strip has, in the direction of deployment, a length less than that of the deployed part.

This structure may for example comprise a solid strip along each of its edges parallel to the direction of deployment.

This of course results in the formation of folds in the deployed part of the structure because it has a length greater than that of the solid strips. However, this does not present a drawback in most applications. The pleated appearance of the structure according to the invention allows, on the contrary, its use in various fields such as that of decoration.

The invention also relates to a filter characterized in that it comprises at least one structure as described above.

This filter can be of any known type in which an expanded metal structure is used for example, but the pleated nature of the structure according to the invention makes it possible to obtain a larger filtering surface for a shorter developed length.

The structure according to the invention can also be used in the production of heat exchangers or electrical resistances because of its large exchange surface with respect to its external dimensions.

The invention also relates to a method of producing an openwork structure of expanded material in which a sheet of this material is simultaneously split and stretched, characterized in that at least one full and unstretched strip is kept parallel to the stretching direction of the sheet.

One can for example keep two full side bands on either side of a split and stretched band.

One can use to implement this method, a conventional machine for producing expanded metal comprising at least one knife forming a succession of teeth and hollows, said knife being arranged to move substantially perpendicular to the surface of the sheet. The knife cooperating with a counter blade splits and simultaneously stretches the sheet. If the knife has a width less than that of the sheet and the latter extends beyond the knife from each of its sides, a structure is obtained whose central part is deployed while the two lateral strips are full.

However, a tool is preferably used according to the invention, the active face of the knife facing the sheet is inclined relative to the surface of this sheet.

The active face can for example be inclined by about 30 °.

Advantageously, said teeth have a progressively decreasing depth towards the end of the knife in order to limit the risks of tearing of the material at the junction between the solid area and the stretched area.

• - la figure 1 est une vue de-dessus d'une structure ajourée selon l'invention,
• - la figure 2 est une vue de-dessus partielle d'une autre structure selon l'invention,
• - la figure 3 est une vue en coupe selon la ligne III-III de la figure 2,
• - la figure 4 est une vue de face d'un outil selon l'invention susceptible d'être utilisé pour la fabrication de stucture telle que celle des figures 1 et 2,
• - la figure 5 est une vue en coupe selon la ligne V-V de la figure 4,
• - la figure 6 est une vue agrandie du détail VI de la figure 4,
• - la figure 7 est une vue agrandie du détail VII de la figure 4 et,
• - la figure 8 est une vue schématique de côté en coupe d'une machine comportant un outil tel que celui des figures 4 à 6.

A particular embodiment of the invention will now be described by way of nonlimiting example with reference to the appended schematic drawings in which:

• FIG. 1 is a top view of an openwork structure according to the invention,
• FIG. 2 is a partial top view of another structure according to the invention,
• FIG. 3 is a sectional view along line III-III of FIG. 2,
• FIG. 4 is a front view of a tool according to the invention capable of being used for the manufacture of a structure such as that of FIGS. 1 and 2,
• FIG. 5 is a sectional view along the line VV in FIG. 4,
• FIG. 6 is an enlarged view of detail VI of FIG. 4,
• FIG. 7 is an enlarged view of detail VII of FIG. 4 and,
• FIG. 8 is a schematic side view in section of a machine comprising a tool such as that of FIGS. 4 to 6.

Figure 1 shows an openwork structure made of a sheet 1 whose central part 2 is deployed. The deployment of part 2 is carried out in the direction of arrow F1.

The sheet 1 comprises in known manner solid end zones 3 in the form of strips perpendicular to the direction F1 of deployment.

The sheet 1 also includes two solid lateral bands 4 parallel to the direction of the arrow FJ and having undergone no stretching during the deployment of the zone 2.

The strips 4 therefore have a length in the direction of the arrow F1 less than the developed length of the zone 2 in this same direction.

This results in a folding of zone 2.

Such a structure such as that shown in FIG. 1 can be advantageously used in a filter because it has, for relatively small external dimensions, a large filtering surface due to the folds produced in zone 2. In addition, the fact that it has solid areas around its periphery makes it possible to easily ensure peripheral sealing and assembly.

FIG. 2 shows another perforated structure according to the invention, also comprising solid lateral bands 4 parallel to the direction F1 of the deployment of the zone 2 and of length less than the length of the deployed zone 2.

However, the meshes of zone 2 are much larger than those of the structure of FIG. 1 and this results in folds whose amplitude d is greater.

The openwork structure of Figure 2 can be presented either as that of Figure 1 with four solid peripheral bands, or with only three bands or even with only two bands.

A structure comprising only the solid strips 4 can advantageously be used as an element of electrical resistance. It also has remarkable rigidity due to the presence of the folds.

FIG. 4 represents a tool capable of being used to produce the structures of FIGS. 1 and 2.

This tool is formed by a blade 5 in which are fixed fixing holes 6. The blade 5 comprises a succession of teeth 7 and recesses 8.

The tool is arranged as shown in FIG. 7 with respect to a counter blade 9 along which a metal strip 10 advances step by step in the direction of arrow F2. At each step, the tool descends perpendicularly to the sheet 10 in the direction of arrow F3 so that its teeth split and simultaneously stretch the metal to form the meshes 11.

Between each descent, the blade moves laterally alternately on one side and the other.

According to the invention, the lower face 12 of the tool which is directed towards the sheet 10 and which comprises the teeth 7 and the recesses 8, makes an angle a with the surface of this sheet which can be. example be equal to 30 °.

The applicant has observed that such an inclination of the face 12 makes it possible to avoid ruptures of the material which may otherwise occur at the junction between the deployed zone 2 and the lateral strips 4.

Furthermore, as shown in FIG. 7, the depth of the teeth gradually decreases towards the end of the knife.

Of course, various variants and modifications can be made to the embodiment described above without departing from the scope or the spirit of the invention.

This is how the teeth of the blade can have any shape other than that shown.

Claims (10)

1. Openwork structure in deployed material, comprising at least one solid strip (4) parallel to the direction of deployment, characterized in that said strip has, in the direction of deployment a length less than that of the deployed part. 2. Structure according to claim 1, characterized in that it comprises a solid strip along each of its edges parallel to the direction of deployment. 3. Filter, characterized in that it comprises at least one structure according to any one of claims 1 and 2. 4. Heat exchanger, characterized in that it comprises at least one structure according to any one of claims 1 and 2. 5. Electrical resistance, characterized in that it comprises at least one structure according to any one of claims 1 and 2. 6. A method of producing an openwork structure of expanded material, in which a sheet of material is simultaneously split and stretched, characterized in that at least one solid and unstretched strip is kept parallel to the direction of sheet stretching. 7. Method according to claim 6, characterized in that two solid side bands are kept on either side of a split and stretched band. 8. Tool for implementing the method according to any one of claims 6 and 7, comprising at least one knife forming a succession of teeth and hollows, said knife being arranged to move substantially perpendicular to the surface of the sheet. , characterized in that the active face (12) of the knife facing the sheet is inclined relative to said surface. 9. Tool according to claim 8, characterized in that said active face is inclined by about 30 °. 10. Tool according to any one of claims 8 and 9, characterized in that said teeth have a progressively decreasing depth towards the end of the knife.

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