FR2615437A1 - DEVICE FOR EXTRUSION OF ALVEOLAR STRUCTURES IN CERAMIC MATERIAL - Google Patents

Abstract

THE EXTRUSION DEVICE IS CONSTITUTED OF A BLOCK IN WHICH IS PERIOD A NETWORK OF ADMISSION HOLES OF THE CERAMIC PASTE, THESE OPENING IN A NETWORK OF SLOTS CROSSING AND FORMING THE ALVEOLAR STRUCTURE WHEN THE PASTE IS EXTRUDED THROUGH THE BLOCK, CHARACTERIZED IN THAT MOST OF THE INTAKE HOLES 10 ARE LOCATED APLOMB OF THE SLOTS 11, OUTSIDE THE INTERSECTIONS 13 OF THE SLOTS 11 AND IN THAT THE DISTRIBUTION OF THESE HOLES IS SUCH AS THE WIDTHS OF THE TAPES OF PASTE EXTRUDES FROM EACH OF THEM ARE SIGNIFICANTLY EQUAL. APPLICATION TO THE REALIZATION OF EXTRUSION BLOCKS ALLOWING TO MANUFACTURE ALVEOLAR PROFILES OF VARIOUS PITCHES AND SHAPES.

Description

2615437

  DEVICE FOR EXTRUSION OF ALVEOLAR STRUCTURES

IN CERAMIC MATERIAL

  The present invention relates to a device for ex-

  trusion of honeycomb structures made of ceramic material and more particularly to a device for the extrusion of such structures & very thin walls (of a few tenths

  millimeter) with a relatively large mesh (honeycomb

  having them a side of at least one millimeter).

  For the extrusion of such structures, it is generally

  a monobloc tool consisting of a network of holes drilled for example in a steel block and opening into a

  a network of crisscrossing slots forming alveolar ceramic

  re proper, when the dough passes through the tooling.

  Three stages can thus be distinguished in the extrusion of the paste through the tooling: in a first step, the paste fills the network of holes and forms a set of parallel cylinders; - In a second step, the dough continues its path and gradually enters the slots adjacent to the holes forming ribbons or cruciform profiles; finally, the dough ribbons weld together,

  to form the honeycomb profile.

  However, when it is desired to produce profiles having a large mesh with respect to the wall thickness (in a ratio, for example, from 1 to 10 or more), or in the case of asymmetrical mesh profiles, the realization of the second step, which passes cylinders to cruciform profiles can be

sometimes difficult to obtain.

  This difficulty can be due to multiple reasons:

-2-2615437

  the dough may lack plasticity, the friction of the dough on the walls, which is at the origin of the lateral spreading of the dough and facilitates the formation of the cross of the profile, may be insufficient. In the latter case, a solution usually

  to run deeper grooves to increase the friction

  but this operation is expensive and, moreover, is

  limited often by the technological possibilities of machining.

  Moreover, it mechanically makes the tools

lages thus modified.

  - the different length of the branches of the cross, in

  the case, for example, of cellular honeycomb with rectangular mesh

  triangular mesh (other than equilateral),

etc ...

  The subject of the present invention is the production of a honeycomb ceramic extrusion device which does not have

not these disadvantages.

  The device according to the invention, intended for the extrusion of honeycomb structures of ceramic material, of the kind consisting of a block in which is drilled a network of ceramic paste inlet holes, these opening into a

  a network of crisscrossing slits forming the alveolar structure

  when the dough is extruded through the block is characterized

  the fact that most of the intake holes are arranged in line with the slots, outside the intersections of the slots and in that the distribution of these holes is such that the widths of the extruded dough ribbons from each of 'them

are substantially equal.

  This arrangement of the holes allows great flexibility

  according to the design of the structure to be produced.

  According to one embodiment of the invention, the network of slots forms polygonal meshes, preferably quadrangular. According to another embodiment of the invention, the

  lattice network forms triangular meshes.

  According to yet another embodiment of the invention, the network of slots consists of concentric circles and

  of rays or parts of rays of these circles.

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  The features of the invention will emerge more clearly

  of the following description, given solely by way of example,

  with reference to the accompanying drawing in which Figures 1 to 4 schematically illustrate embodiments of the extrusion device according to the invention and more particularly the relative arrangement of the dough inlet holes and exit slots. of it, in an extrusion tool,

in partial view from above.

  In the case of the embodiment of Figure 1, the honeycomb structure has a square mesh. The top view shows, in solid lines, the dough inlet holes 10 and, in interrupted line, the network of the dough outlet slots 11, corresponding to the design of the honeycomb structure. The entrance lips of these slots naturally appear in solid lines, at 12, at the bottom of each of the holes. According to the invention, the holes 10 are not arranged,

  as is usually the case, in line with the intersec-

  slits, but, symmetrically with respect to these

  slots, outside intersections.

  The holes 10 are distributed in such a way that the dough issuing from the holes in the form of cylinders is distributed in the slots along the paths indicated by the arrows.

  ribbons of equal or substantially equal widths.

  In the case of Figure 2, the mesh of the honeycomb structure is triangular. For this figure, as for the two following ones, elements similar to those of the

  Figure 1 are designated by the same references.

  On the network of the slots 11, forming triangles, the holes 10 are arranged outside the intersections 13 and, again, the distribution of these holes is such that the widths

  extruded ribbons in the slots between holes remain

from each other.

  Figure 3 corresponds to a network of rectangular mesh slots. To keep substantially constant the width of the slots between the holes 10, two of these holes are arranged on the largest side of the rectangle and only one on the short side.

4 2615437

  In the embodiment of Figure 4, the slots 11 form concentric circles 11a and 11b rays of these circles; the holes are arranged in a distribution ensuring a width substantially equal to the extruded dough ribbons in these slots, from each of the holes, these being arranged

  mostly out of intersections 13. However,

  some holes, designated 10a, are arranged on

  intersections 13 to optimize the distribution of

  bution. The device according to the invention makes it possible to increase in a very significant way, the possibilities offered to ceramists to manufacture honeycomb profiles of steps and shapes.

very varied.

  The tooling according to the present invention is entirely

  particularly suitable for the extrusion of elements intended to be subjected to high temperatures and pressures, for example filter elements for liquid metals, in which case

  these elements are made of refractory materials.

  Of course, the present invention is not limited to the embodiments described and shown and is capable of numerous variants accessible to the man of

  art, without departing from the spirit of the invention.

2615437

Claims (4)

  1.- Device for extruding honeycomb structures of ceramic material, of the kind consisting of a block in which is drilled a network of ceramic paste inlet holes, these opening into a network of slots intersecting and forming the honeycomb structure when the paste is extruded through the block, characterized in that most of the intake holes (10) are arranged in line with the slots (11), outside the intersections (13) of the slots (11). ) and that the distribution of these holes is such that the widths of the   extruded dough ribbons from each of them are sensi- equally equal.   2.- Device according to claim 1, characterized in that the network of slots (11) form polygonal meshes, preferably quadrangular.   3.- Device according to claim 1, characterized in   the network of slots (11) forms triangular meshes   res. 4.- Device according to claim 1 characterized in that the network of slots (11) consists of concentric circles (lla) and radii (llb) or parts of spokes of these circles.