CROWN FOR KILNS AND THE LIKE

Description

TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to a vault for kilns and the like.

[0002] More in particular, the present invention relates to a vault for kilns for baking ceramic products such as tiles and the like.

PRIOR ART

[0003] In the field of manufacture of ceramic products, such as tiles and the like, product baking kilns of the so-called roller type are traditionally used. Such kilns comprise a long support structure or framing, which extends horizontally by tenths of metres, which therein defines a feeding channel for the products being baked on a roller conveyor.

[0004] The preheating and/or baking heat of the ceramic products is provided through a certain number of burners, distributed along the feeding channel of the ceramic products, at a predetermined distance from one another and on the two sides.

[0005] The product feeding channel is usually delimited, at the top and at the bottom, by horizontal walls made of refractory and thermally insulating materials which, besides retaining the heat within the kiln, preventing it from being dispersed, to a certain extent also contribute to providing heat to the products being baked by irradiation.

[0006] In known kilns, the top vault of the kiln is essentially made according to two types of structure. The first known structure, of the so-called block type, actually comprises a distribution of suspended blocks, made of insulating material, which as said carry out the dual function of thermally insulating the combustion chamber from the exterior and contributing to the heat diffusion within the product zone by irradiation.

[0007] Such blocks preferably have a parallelepiped shape, and usually have a height quite considerable for ensuring the thermal insulation. Moreover, they are provided each with a respective metal hook, made of stainless steel, for example fixed to an eyelet obtained on a sheet, partly incorporated within the same block. Each metal hook is adapted to fix the respective refractory block to a respective metal beam, preferably arranged crosswise relative to the feeding direction of the products within the kiln.

[0008] In this way, by providing a succession of metal beams on the entire length of the combustion chamber, rows of side-by-side blocks are obtained, which follow one another at regular intervals so as to substantially cover the entire top portion of the combustion chamber. The second vault structure of the known type, on the other hand, is the so-called sheet type.

[0009] In this type of structure, the insulating-irradiating surface consists of a distribution of sheets, of quite small thickness, which along the external edges rest on support elements provided each with respective hooks that, as in the case of the block structure, allow fixing to the crosswise metal beams.

[0010] Since as said, the sheet thickness is quite small, in order to ensure the required thermal insulation it is then necessary to provide for further layers of light insulating material, for example consisting of ceramic fibres or the like, arranged on top of the sheets.

[0011] As noted, both types of vault structures share the same suspended fixing mode, that is, the use of metal hooks clung to crosswise metal beams.

[0012] This fixing mode exhibits some drawbacks.

[0013] In the first place, it does not ensure the perfect closing of the combustion chamber, due to the presence of multiple hooks that cross the outer insulating layer, with a density of about 32 hooks/m² for the block vault, and 16 hooks/m² for the sheet vault. For this reason, the corrosive gases coming from within the kiln, among the other things containing fluorine and sulphur compounds, tend to escape leading, among the other things, to a quick corrosion of the metal parts, with consequent fall of the parts hooked thereto.

[0014] Besides this, with particular reference to the sheet structure, it is especially difficult and complicated to lay the further layers of insulating material on top of the sheet, required to ensure the optimal thermal insulation, since the support hooks of the same sheets constitute cumbersome hindrances, often very close to one another, among which it is necessary to unravel. The layers of insulating material must necessarily be made into portions, with small sized strips or loose ceramic fibre, which do not provide an optimal insulation and do not ensure the tight seal of the top vault. DE 38 41 109 A1 describes a system for defining a top closing surface build up by support beams which are inserted through openings of insulating L-shaped elements.

OBJECTS OF INVENTION

[0015] The technical task at the basis of the present invention therefore is to provide a vault of kilns and the like free from fixing elements subject to corrosion by the gases coming from within the kiln, which cross the outer insulating layer.

[0016] within such technical task, an object of the present invention according to claim 1 is to provide a vault of kilns and the like, wherein the insulating elements that make it up are fixed to the top of the combustion chamber so as to form a substantially sealed closing surface impenetrable by said corrosive gases coming from within the kiln.

[0017] Yet another object of the present invention is to provide a vault of kilns and the like which allows an effective thermal insulation to be obtained at the top of the combustion chamber, in a simple, practical, safe and inexpensive manner.

[0018] This task and these objects are achieved by the vault of kilns and the like according to the annexed claim 1, comprising a plurality of hung support beams of insulating and/or radiant elements adapted to define a top closing surface of the kiln combustion chamber, and also comprising, for at least some of the support beams, at least one support of refractory material, provided with at least one through opening for inserting the support beam, and supporting means, at at least one of the sides, for at least one respective insulating and/or irradiating element.

[0019] Further advantageous features are described in the dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The features of the invention shall be better understood by any man skilled in the art from the following description and annexed drawing tables, provided by way of a non-limiting example, wherein:

figure 1 shows a cross section of a kiln for ceramic products provided with the vault according to the present invention;

figure 2 shows a longitudinal section view of a portion of the kiln of figure 1;

figure 3 shows a longitudinal section of the kiln portion of figure 2, wherein the vault according to the present invention is surmounted by layers of insulating material;

figure 4 shows a detail of figure 2;

figure 5 shows an enlargement of figure 1.

EMBODIMENTS OF THE INVENTION.

[0021] With reference to the annexed figure 1, reference letter K globally denotes a kiln for baking ceramic products and the like, whereas reference numeral 1 denotes the vault of kiln K according to the present invention, which at the top closes the combustion chamber C of kiln K according to the modes that shall be explained hereinafter in the description.

[0022] The illustrated kiln K is, in particular, of the roller type - with reference to the transport means of the ceramic products therein - and is adapted to carry out the preheating and/or baking step of ceramic products such as tiles and the like, although it may also be used for products of a different shape and/or different nature, without limitations to the scopes of the present invention.

[0023] Moreover, other transport means may also be used, as an alternative to the rollers, to feed the ceramic products along the kiln.

[0024] As is visible in the longitudinal section of figure 1, the kiln comprises a support structure or framing, globally indicated with reference numeral 2. Framing 2, for example made of steel or other material of suitable mechanical and heat resistance features, horizontally extends by a variable length in relation to the specific application requirements, but which may even reach various tenths of metres.

[0025] Framing 2 consists of a plurality of modules, connected to one another in a series in the feeding direction A of the ceramic products.

[0026] The number of modules that make up kiln 1 may clearly be any, without limitations.

[0027] More or less extended preheating, baking and cooling zones may typically be provided within kiln K.

[0028] Each of such zones, therefore, comprises a certain number of modules connected in a series along the product feeding direction A.

[0029] Each module of kiln K consists of vertical uprights 4, horizontal crosspieces 6 and longitudinal members, reciprocally connected so as to form substantially parallelepiped structures, in a manner per se known in the field.

[0030] Each module of kiln K comprises, substantially at base 8 and at the side walls 10, portions of insulating material, according to modes known in the field: such insulating material consists, for example, of refractory materials, ceramic materials and the like, variously combined and- distributed in relation to the specific requirements.

[0031] The portions of insulating material of base 8 and of the side walls 10 thereinbetween define a volume that crosses kiln 1 essentially by the entire length thereof, from an inlet to an outlet.

[0032] Such volume therefore constitutes the combustion chamber C for the products being baked: in particular, the products move on a feeding plane P, located for example in the middle of the combustion chamber C.

[0033] The product feeding plane P is defined by rollers with cross axis relative to the product feeding direction A. The rollers, associated to' respective driving means, are not shown in the figures for simplicity of understanding and because they are of the essentially known and traditional type: in the specific features thereof, in any case, they are not an object of the present invention.

[0034] Burners, of the essentially known type, are arranged along the combustion chamber C, and in particular in the preheating and heating zones, which in the specific features thereof do not constitute an object of the present invention, and which are not shown in the figures.

[0035] The burners are arranged crosswise relative to the feeding direction A of the products being baked, and are associated to respective means for feeding air and fuel, not shown in the figures, in any case of the known type.

[0036] The burners are arranged at both sides of the combustion chamber C, for example alternating on the right and on the left, and also at the top and at the bottom relative to the product feeding plane P.

[0037] The distribution of the burners within the combustion chamber C may in any case be whatever, for example they may be concentrated in some specific zones, etcetera. Vault 1 of kiln K is supported on the side walls 10 of framing 2.

[0038] A top or roof 12 for closing kiln K, supported by framing 2, essentially of the traditional type, is further provided above vault 1.

[0039] As is known, the function of vault 1 of kiln K is to provide a surface, substantially continuous, thermally insulating, of the combustion chamber C, and radiant as well: in other words, such surface allows the heat dispersion from within the combustion chamber C outwards to be limited, and also contributes to irradiating the heat produced by the burners towards the products being baked within the same kiln K.

[0040] Vault 1 - as clearly illustrated in figure 2 - comprises a plurality of hung support beams 14 of insulating and/or radiant elements 16, adapted to define a top closing surface of the combustion chamber C of kiln K.

[0041] Beams 14 are mounted, at the respective ends 18, substantially on the top of the side walls.

[0042] More in particular, ends 18 of beams 14 rest on plates 20 of refractory material, provided on the top of the side walls of framing 2, also visible in the detail of figure 5: said plates 20 allow the load consisting of the weight of beams 14 to be distributed on a sufficiently wide and suitably hard surface.

[0043] Moreover, the solution of resting ends 18 of the beams on plates 20 allows the same beams 14 to be mounted and removed with extreme easiness and rapidity in the case of maintenance operations, replacement, etc.

[0044] According to an aspect of the present invention, vault 1 comprises, for at least some of the support beams 14, or preferably for all beams 14 mounted within kiln K, at least one support of refractory material, globally indicated with reference numeral 22, for the insulating and/or radiant elements 16, described in detail hereinafter.

[0045] As illustrated in figure 4, each support 22 is provided with at least one through opening 24 for inserting the support beam 14.

[0046] Each support 22 is further provided with supporting means 26, at at least one of the sides, for at least one respective insulating and/or radiant element 16. The insulating and/or radiant element is therefore arranged parallel relative to beam 14.

[0047] More in detail, each support 22 comprises a coupling portion 28 with the respective support beam 14.

[0048] The coupling portion 28 of each support 22 has a closed cross section and with substantially rectangular or trapezoidal shape, so as to define the through opening 24 for inserting the respective support beam 14.

[0049] For example, the coupling portion 28 has a section with even thickness of 4 or 5 mm.

[0050] The supporting means 26 of each support 22 comprise an enlarged end portion 30 protruding at the sides, so as to form a symmetrical structure relative to the vertical centre line plane V, as shown in figure 4.

[0051] The supporting means 26 of each support 22 further comprise a plate element 32.

[0052] The plate element 32 is provided at the top with coupling means 34 with the end portion 30.

[0053] On the side, the plate element 32 is further provided with at least one substantially horizontal surface 36 for supporting a corner 38 of at least one respective insulating and/or radiant element 16.

[0054] More in detail, the plate element 32 is provided on the side with two substantially horizontal surfaces 36, symmetrical relative to the vertical centre line plane V, for supporting corners 38 of two respective insulating and/or radiant elements 16, as shown in figure 4.

[0055] The coupling means 34 comprise a pair of relief portions 40, parallel to one another and bent towards one another substantially at a right angle. The relief portions 40 thus define a sort of dovetail guiding surface 42 for inserting the end portion 30.

[0056] In another embodiment, each support 22 may be made in a single piece with the respective plate element 32.

[0057] As shown in figure 1, a plurality of supports 22 for the insulating and/or radiant elements 16 may be inserted side by side along a same beam 14.

[0058] The number of supports 22 inserted along a same support beam 14 is clearly variable in relation to the longitudinal dimensions of supports 22 and of the same plate elements 32; said longitudinal dimensions in turn vary in relation to other design specifications, such as for example the dimensions and weight of the insulating and/or radiant elements 16 to be supported, and still others.

[0059] According to an aspect of the present invention, each support 22 - that is, in detail, the respective coupling portion 28 and the respective plate element 32 - is made of refractory material of the cordierite type or the like, of per se known use in the field of kiln manufacture and the like, for its properties of resistance to high temperatures and, among the other things, with a high hardness and limited thermal expansion.

[0060] According to another aspect of the present invention, beams 14 for supporting the insulating and/or radiant elements 16 are made of refractory material.

[0061] More in detail, such beams 14 are made of refractory material of the silicon carbide type or the like.

[0062] Each one of beams 14 has a substantially rectangular closed cross section, with thickness, for example, of a few millimetres.

[0063] As an alternative, each one of beams 14 has an open shape cross section, for example shaped as a C, T, H, or other typical shapes for beam construction.

[0064] The insulating and/or radiant elements 16 that make up vault 1 are shaped as a substantially flat sheet, in an essentially per se known manner. The insulating and/or radiant elements 16 are made of refractory material that is known in this type of applications.

[0065] As is visible in figures 2, 3, the insulating and/or radiant elements 16 are therefore mounted interposed between two consecutive beams 14 and, since they are arranged parallel to these, they are easily mounted and removed individually, without having to remove the same beams 14 or extract supports 22.

[0066] Vault 1 according to the invention further comprises at least one thermally insulating layer 44, for example made of a material comprising ceramic fibres or the like of a type that is known in the field, interposed between the insulating and/or radiant elements 16 and top 12 of framing 2.

[0067] More in detail, as shown in figure 3, vault 1 preferably comprises a plurality of thermally insulating layers 44, overlapped to one another, and interposed between the insulating and/or radiant elements 16 and top 12 of framing 2.

[0068] The invention thus conceived allows obtaining important technical advantages.

[0069] In the first place, the hung support of the insulating and/or radiant elements 16 is obtained without the use of any metal component, but only using components made of refractory materials, in particular for example cordierite for supports 22 and silicon carbide for the support beams 14. In this way, no corrosion effects occur which may impair the structure stability, nor undesired thermal expansions, and other harmful phenomena due to the use of metal components.

[0070] Moreover, vault 1 according to the invention allows providing a safer and more sealed top closure of the combustion chamber C, since the mounting of supports 22 onto the respective beams 14, through the coupling portions 28, is characterised by a higher stability and solidity compared to what happens in traditional vaults, wherein metal hooks are used. This safer and more effective closure of the combustion chamber C has the dual advantage of obtaining a better thermal insulation and effectively inhibiting the top escape of corrosive gases that may potentially affect other portions of kiln K.

[0071] Also, the particular shape of supports 22 allows layers 44 of insulating material to be installed above the insulating and/or radiant elements 16 in a much easier and more functional manner. As is visible in figure 2, such layers 44 may in fact consist of portions or strips of much larger dimensions than those that can be installed with vaults of the traditional type, provided with metal hooks that cross them. It is even possible to obtain layers 44 by the continuous laying of insulator rolls by the entire kiln length.

[0072] Such strips or portions of layers 44, moreover, are inserted with a certain accuracy between the coupling portions 28 of adjacent rows of supports 22, so as to obtain, in vault 1, a compact and even insulation, with minimised discontinuities.

[0073] These advantages are achieved thanks to the fact that the radiant and/or insulating elements 16 are arranged parallel to beams 14, and supported between adjacent beams 14, so that the volume towering above them is completely free, usable and completely accessible.

[0074] It has thus been seen that the invention achieves the intended objects.

[0075] The present invention has been described according to preferred embodiments but equivalent versions may be conceived without departing from the scope of protection offered by the following claims.

Claims

1. Vault of kilns and the like, in particular for kilns for baking ceramic products, comprising a plurality of hung support beams (14) of insulating and/or radiant elements (16) adapted to define a top closing surface of the combustion chamber (C) of the kiln (K) and, for at least some of said support beams (14), at least one support (22) of refractory material, provided with at least one through opening (24) for inserting said support beam (14), and supporting means (26), at at least one of the sides, for at least one respective insulating and/or radiant element (16), said insulating and/or radiant element (16) being arranged parallel to said beam (14), and
characterised in that
said beams (14) are made of refractory material.

2. Vault according to claim 1, wherein said support (22) comprises at least one coupling portion (28) with said beam (14), having a closed cross section and with substantially rectangular shape so as to define said through opening (24).

3. Vault according to claim 1 or 2, wherein said supporting means (26) comprise an end portion (30) of said support, enlarged and protruding at the sides.

4. Vault according to claim 3, wherein said supporting means (26) comprise a plate element (32) provided at the top with coupling means (34) with said end portion (30) and, at the side, with at least one substantially horizontal surface (36) for supporting a corner (38) of at least one respective insulating and/or radiant element (16)

5. Vault according to claim 4, wherein said plate element (32) is made in a single piece with the respective support (22).

6. Vault according to claim 4 or 5, wherein said plate element (32) on the side comprises two symmetrical substantially horizontal surfaces (36) for supporting respective corners (38) of respective insulating and/or radiant elements (16).

7. Vault according to one of the previous claims, wherein said coupling means (34) comprise a pair of relief portions (40) parallel to one another and bent towards one another so as to define a sort of dovetail guiding surface (42) for inserting said end portion (30).

8. Vault according to one of the previous claims, wherein said support (22) is made of refractory material of the cordierite type or the like.

9. Vault according to the previous claim, wherein said beams (14) are made of refractory material of the silicon carbide type or the like.

10. Vault according to one of the previous claims, wherein said insulating and/or radiant elements (16) are shaped as a substantially flat sheet.

11. Vault according to the previous claim, comprising at least one thermally insulating layer (44) interposed between said insulating and/or radiant elements (16) and the top (12) of said vault.

12. Vault according to one of the previous claims, comprising a plurality of said supports (22) inserted side by side along a same beam (14).

13. Vault according to one of the previous claims, wherein said beams (14) are mounted with the respective ends (18) resting onto respective plates (20) provided on the top of the side walls of the kiln framing (2).

Ansprüche

1. Gewölbe von Öfen und dergleichen, insbesondere für Öfen zum Brennen von keramischen Produkten, umfassend eine Vielzahl von aufgehängten Tragbalken (14) aus Isolier- und/oder Strahlungselementen (16), die so ausgebildet sind, dass sie eine obere Schließfläche der Brennkammer (C) des Ofens (K) und, für mindestens einige der besagten Tragbalken (14), mindestens einen Träger (22) aus feuerfestem Material bilden, versehen mit mindestens einer Durchgangsöffnung (24) zum Einsetzen des besagten Tragbalkens (14), und von Tragmitteln (26), an mindestens einer der Seiten, für mindestens ein entsprechendes Isolier- und/oder Strahlungselement (16), wobei das besagte Isolier- und/oder Strahlungselement (16) parallel zu dem besagten Balken (14) angeordnet ist, und
dadurch gekennzeichnet, dass
die besagten Balken (14) aus feuerfestem Material bestehen.

2. Gewölbe nach Anspruch 1, worin der besagte Träger (22) mindestens einen Verbindungsabschnitt (28) mit dem besagten Balken (14) mit einem geschlossenen Querschnitt und mit einer im Wesentlichen rechteckigen Form umfasst, um die besagte Durchgangsöffnung (24) zu bilden.

3. Gewölbe nach Anspruch 1 oder 2, worin die besagten Tragmittel (26) einen Endabschnitt (30) des besagten Trägers umfassen, der an den Seiten vergrößert ist und vorsteht.

4. Gewölbe nach Anspruch 3, worin die besagten Tragmittel (26) ein Plattenelement (32) umfassen, dass an der Oberseite mit Verbindungsmitteln (34) mit dem besagten Endabschnitt (30) und an der Seite mit mindestens einer im Wesentlichen horizontalen Fläche (36) zum Tragen einer Ecke (38) mindestens eines entsprechenden Isolier- und/oder Strahlungselements (16) versehen ist.

5. Gewölbe nach Anspruch 4, worin das besagte Plattenelement (32) einstückig mit dem entsprechenden Träger (22) ausgebildet ist.

6. Gewölbe nach Anspruch 4 oder 5, worin das besagte Plattenelement (32) auf der Seite zwei symmetrische im Wesentlichen horizontale Flächen (36) zum Tragen entsprechender Ecken (38) entsprechender Isolier- und/oder Strahlungselemente (16) umfasst.

7. Gewölbe nach einem der vorangegangenen Ansprüche, worin die besagten Verbindungsmittel (34) ein Paar zurückspringende Abschnitte (40) umfassen, die parallel zueinander und aufeinander zu gebogen sind, um eine Art schwalbenschwanzförmige Gleitfläche (42) zum Einsetzen des besagten Endabschnitts (30) zu bilden.

8. Gewölbe nach einem der vorangegangenen Ansprüche, worin der besagte Träger (22) aus feuerfestem Material des Cordierittyps oder dergleichen besteht.

9. Gewölbe nach dem vorangehenden Anspruch, worin die besagten Balken (14) aus feuerfestem Material des Siliciumcarbidtyps oder dergleichen bestehen.

10. Gewölbe nach einem der vorangegangenen Ansprüche, worin die besagten Isolier- und/oder Strahlungselemente (16) als eine im Wesentlichen flache Platte geformt sind.

11. Gewölbe nach dem vorangehenden Anspruch, umfassend mindestens eine wärmeisolierende Schicht (44), die zwischen den besagten Isolier- und/oder Strahlungselementen (16) und der Oberseite (12) des besagten Gewölbes angeordnet ist.

12. Gewölbe nach einem der vorangegangenen Ansprüche, umfassend eine Vielzahl von Trägern (22), die nebeneinander entlang eines gleichen Balkens (14) eingesetzt sind.

13. Gewölbe nach einem der vorangegangenen Ansprüche, worin die besagten Balken (14) mit den entsprechenden Enden (18) aufliegend auf entsprechenden Platten (20), die auf der Oberseite der Seitenwände des Ofenrahmens (2) vorgesehen sind, montiert sind.

Revendications

1. Voûte de fours et analogues, en particulier pour des fours de cuisson de produits en céramique, comprenant une pluralité de poutres de support suspendu (14) d'éléments isolants et/ou rayonnants (16) adaptés pour définir une surface de fermeture supérieure de la chambre de combustion (C) du four (K) et, pour au moins certaines desdites poutres de support (14), au moins un support (22) de matériau réfractaire, doté d'au moins une ouverture traversante (24) pour insérer ladite poutre de support (14), et des moyens de support (26), sur au moins un des côtés, pour au moins un élément isolant et/ou rayonnant (16) respectif, ledit élément isolant et/ou rayonnant (16) étant agencé parallèlement à ladite poutre (14), et
caractérisée en ce que
lesdites poutres (14) sont constituées de matériau réfractaire.

2. Voûte selon la revendication 1, dans laquelle ledit support (22) comprend au moins une partie de couplage (28) avec ladite poutre (14), ayant une section transversale fermée et une forme sensiblement rectangulaire de façon à définir ladite ouverture traversante (24).

3. Voûte selon la revendication 1 ou 2, dans laquelle lesdits moyens de support (26) comprennent une partie d'extrémité (30) dudit support, agrandie et saillante sur les côtés.

4. Voûte selon la revendication 3, dans laquelle lesdits moyens de support (26) comprennent un élément de plaque (32) doté au sommet de moyens de couplage (34) avec ladite partie d'extrémité (30) et, sur le côté, d'au moins une surface (36) sensiblement horizontale pour supporter un angle (38) d'au moins un élément isolant et/ou rayonnant (16) respectif.

5. Voûte selon la revendication 4, dans laquelle ledit élément de plaque (32) est fabriqué d'une seule pièce avec le support (22) respectif.

6. Voûte selon la revendication 4 ou 5, dans laquelle ledit élément de plaque (32) sur le côté comprend deux surfaces (36) sensiblement horizontales symétriques pour supporter des angles (38) respectifs des éléments isolants et/ou rayonnants (16) respectifs.

7. Voûte selon l'une des revendications précédentes, dans laquelle lesdits moyens de couplage (34) comprennent une paire de parties en relief (40) parallèles l'une à l'autre et courbées l'une vers l'autre de façon à définir une sorte de surface de guidage en queue d'aronde (42) pour insérer ladite partie d'extrémité (30).

8. Voûte selon l'une des revendications précédentes, dans laquelle ledit support (22) est constitué de matériau réfractaire du type cordiérite ou analogue.

9. Voûte selon la revendication précédente, dans laquelle lesdites poutres (14) sont constituées de matériau réfractaire du type carbure de silicium ou analogue.

10. Voûte selon l'une des revendications précédentes, dans laquelle lesdits éléments isolants et/ou rayonnants (16) sont en forme de plaque sensiblement plate.

11. Voûte selon la revendication précédente, comprenant au moins une couche isolante thermiquement (44) intercalée entre lesdits éléments isolants et/ou rayonnants (16) et le sommet (12) de ladite voûte.

12. Voûte selon l'une des revendications précédentes, comprenant une pluralité desdits supports (22) insérés côte à côte le long d'une même poutre (14).

13. Voûte selon l'une des revendications précédentes, dans laquelle lesdites poutres (14) sont montées avec leurs extrémités (18) respectives reposant sur des plaques (20) respectives disposées au sommet des parois latérales de la structure du four (2).

Drawing