EP0200984A1 - Kiln furniture - Google Patents

Abstract

Kiln furniture for supporting ceramic products to be baked in a high-speed baking kiln includes an inorganic fibrous material needled blanket having a plurality of depressions therein, and a plurality of separate basic bodies of a ceramic material mounted in the depressions and forming an upper emplacement surface for supporting the ceramic products.

Description

The invention relates to a firing aid for ceramic products to be fired in particular in the rapid firing furnace, which consists of a ceramic base material, with a mounting surface which is in contact with the conveyor of the furnace, in particular a tunnel car, and with a footprint for the firing material. The kiln furniture can be used with advantage in high-speed furnaces, where it is known that very different conveyors, e.g. roller conveyors are also provided.

Most ceramic products, especially fine ceramic products such as porcelain, are fired on or in kiln furniture at high temperatures. The firing is carried out in differently designed firing plants, to a large extent even today in tunnel kilns. The kiln furniture, e.g. Slabs and supports, built up in tiers, whereby the fired goods appear to be stacked several times on the individual floors. It is also known to use firing capsules whose dimensions are adapted in a special way to the dimensions of the firing material. Most of the firing processes used require long furnace cycles from cold to cold, even with relatively short overrun times. In addition to the obvious disadvantage of a high energy requirement of such tunnel kilns, it is not or only inadequately possible to automate the loading and unloading of the ceramic products from the tunnel car due to the variety of ceramic products to be burned and in particular because of the tier-like structure on the tunnel car.

The furnace construction industry has been taking this into account for a long time and has developed so-called rapid-fire furnaces wraps. In contrast to conventional tunnel kilns, these rapid firing kilns are not lined with heavy refractory products with a high heat storage capacity and large wall thicknesses, but are essentially lined with ceramic fiber materials Heat storage capacity and thus low energy loss when starting and stopping the furnace, as well as an extraordinarily high resistance to temperature changes due to its fibrous structure. These advantages of the ceramic fiber materials are used in the high-speed furnaces, in which the ceramic products are usually only passed through the high-speed furnace in one position, i.e. not in tier-like structures, with extremely short thrust times. Due to their specific advantages, these rapid firing stoves do not have to be operated continuously, but can be switched on and off periodically without major energy losses.

In-depth tests and examinations have shown that most ceramic products, especially fine ceramic products, could be fired much faster than previously possible without any loss of quality. In practice, however, this was not possible because the known firing aids, as fired ceramic products, are not able to withstand the harsh operating conditions of the rapid firing furnaces, particularly because of the insufficient resistance to temperature changes. Despite considerable efforts, it has so far not been possible to improve the known firing aids, which mostly contain cordierite or silicon carbide as the main constituent, in the thermal shock resistance so that they can be used economically in a rapid firing furnace.

The invention has for its object to show a kiln furniture, which has the high thermal shock resistance required in particular for high-speed furnaces, so that this opens up the possibility of many ke Ramatic products, which were previously burned in the tunnel kiln in particular, are now much cheaper and faster to burn in the rapid kiln.

According to the invention, this is achieved in that the kiln furniture is constructed in several parts. The invention turns away from the prior art, according to which kiln furniture consisted of a fired ceramic material, that is to say in the form of solid bodies, the dimensions of which - often with a complicated shape - were closely adapted to the dimensions of the respective firing material . For example, capsules for burning plates were dimensioned larger than the plate to be burned, and the stresses in the capsule that occur when the temperature changes lead to the known disadvantages with the useful life of this kiln furniture of only a few oven cycles. The present invention goes a completely new way in that the kiln furniture is made in several parts and the individual parts consist of completely different materials. The kiln furniture according to the invention is therefore generally made of an inorganic fiber material forming the contact surface in the form of a binder-free needled fiber mat (blanket) or in the form of a needled fiber mat impregnated with an inorganic binder and of a ceramic material forming the footprint in the form of segment-like base bodies and / or assembled in the form of a fire-resistant coating. The fiber mat has a relatively large shape, which is not disadvantageous because of the high thermal shock resistance of the fiber material. According to one embodiment, the firing aid consists of a fiber mat forming the contact surface and of a plurality of rod-like or segment-like basic bodies made of ceramic material, which are held in a stable position relative to one another in grooves, slots or other depressions of the fiber mat and form the overall installation surface for the fired goods. The fiber mat has multiple functions. It isolates the conveyor from the combustion chamber and enables the stable positioning of the individual base bodies from the fired kerami material to each other, so that the base body as a whole form the footprint for the kiln. The base bodies made of the fired ceramic material have in particular a relatively small dimension and a simple shape, so that they themselves are also able to withstand the thermal shock conditions. The base body can thus also have thin wall thicknesses. It is even possible to use such ceramic materials that were previously considered unsuitable for the production of kiln furniture. Above all, however, the shape of the base bodies no longer aligns with the dimensions and shape of the firing material. The only condition to be complied with is that the base body as a whole must form a sufficiently stable footprint for the firing material. The fiber mat can easily be produced with such stability that the base body hardly sinks into the fiber material even when loaded with the firing material, and thus the installation surface for the firing material remains largely stable. For example, the fiber mat, which is usually to be understood as meaning a binder-free needled fiber mat (blanket), can be impregnated with an inorganic binder, such as monoaluminum phosphate. In particular, in the rapid firing furnace, mostly only one layer is fired, so that the weight acting on the fiber mat from the base bodies and the firing material is limited. This - peculiarity of single-layer firing in rapid firing ovens therefore complements advantageously with the new kiln furniture and enables the use of the fiber mat as a component of the kiln furniture. On the other hand, the new kiln furniture in conjunction with rapid firing furnaces has the further advantage that the putting on and taking off of the kiln goods can be automated in a simple manner. In the case of changing firing material, there is the possibility not only of automatically putting the firing material itself on and off, but also of automatically placing the base body on the fiber mat in the correct place and of putting the firing material on, for example, in a second loading station. It is also possible to thaw the entire kiln furniture, including the fiber mat, when the firing material changes or store with the basic bodies left until the same or similar items are fired again. If the fiber mats are not rigid, but flexible, such firing aids, including the left basic body, can also be rolled up, for example for storage. The size of the fiber mat can be adapted to the size of the individual ceramic product to be burned or also to the size of the conveyor in the furnace, so that a mat that is continuous over the entire plateau of a kiln car can also be used. Finally, it is also advantageous that damaged base bodies, which only form part of the kiln furniture, can be replaced very easily and inexpensively. The fiber mat and the other base bodies can generally be reused.

The basic bodies expediently have a cross section which is not susceptible to thermal shock, in particular a rectangular, T-shaped, U-shaped or I-shaped cross section, and have a limited length. The base bodies generally have small wall thicknesses so that they can be heated up and cooled down quickly without the base bodies having destructive thermal stresses in them. If the footprint of a base body is too small for the intended application, several such base bodies, e.g. in the form of thin plates, placed side by side in a recess in the fiber mat. The base body can have a wall thickness of 0.5 to several millimeters and only a few centimeters. own carrier webs of meter long or as up to e.g. 3 cm wide, thin carrier plates, which also have to be only a few centimeters long, are formed. It is of course expedient to give the base bodies such a cross section that they can be mass-produced inexpensively by the extrusion process.

With their footprint, the base body can be inserted into the fiber mat in such a way that it protrudes beyond the surface of the fiber mat. In this way it is prevented that a Part of the firing material comes into direct contact with the fiber mat, which could lead to the material of the fiber mat sticking to the firing material. In the case of specially designed firing material, for example one which is provided with support feet, the installation surface formed by the base body can also lie in the surface of the fiber mat or even outside of it.

The fiber mat can have a field or a matrix of optional grooves, slits or other recesses for inserting the base body, so that the automated assembly options for the firing aids themselves and the automated placement of the firing material as well as the removal of the conveyor in question at the end are particularly useful of the rapid firing furnace. This makes it possible to carry out the composition of the kiln furniture and the stocking in a program-controlled manner.

If the base bodies in the grooves, slots or other depressions are not sufficiently stable or are sufficiently stable in all directions due to the inherent elasticity of the fiber mat and / or the limitation of the grooves, it is possible within the grooves, slots or other depressions - shoulders or Provide openings and equip the base body with appropriate approaches, knobs or the like. - So that by fitting or inserting a base body. on the fiber mat is stable in all directions and thus held in position. Instead of the shoulders, openings, knobs and the like, it is also possible to fix the base body to the fiber mat by gluing in order to achieve the positionally stable positioning.

The kiln furniture constructed in several parts according to the invention advantageously consists of a fiber material based on aluminum oxide and of segment-like ceramic base bodies based on silicon carbide, aluminum silicate or aluminum oxide.

According to a further embodiment of the invention more Firing aid constructed in part can also consist of a fiber mat that has been provided with a refractory coating instead of or in addition to the segment-like, ceramic base bodies. A fiber material based on aluminum oxide can also be used here, advantageously in the form of a needled fiber mat which has been impregnated with an inorganic binder, such as monoaluminum phosphate, and then dried. The refractory coatings used are preferably those based on silicon carbide or aluminum oxide. These coatings are applied in the usual known manner by dipping, spraying, rolling or brushing, for example in the form of a mixture liquefied with water

After application, these coatings are dried and then fired fireproof. In order to avoid flaking of the refractory coating, it is advantageous to provide the coating with a grid of incisions or punchings after drying and before firing, for example with a system of cuts running at right angles to one another or with a stamped hexagon grid.

• Figur 1: Brennhilfsmittel, erste Ausführungsform, Ansicht von oben (top view),
• Figur 2 Ausführungsform und Anordnung der Grundkörper in bis der Fasermatte im Querschnitt entlang der Linie
• Figur 8 II - II in Figur 1,
• Figur 9 Schnitt in einer gegenüber Figur 2 um 90° gedrehten Schnittrichtung,
• Figur 10 perspektivische Teilansicht eines Grundkörpers,
• Figur 11 Querschnitt durch ein Brennhilfsmittel mit auf- gesetztem Brenngut,
• Figur 12 Ansicht von oben einer feldartig ausgebildeten Fasermatte,
• Figur 13 eine ähnliche Schnittdarstellung wie Figur 9 durch eine Matte gemäß Figur 12 und
• Figur 14 Ausschnitt aus einer Ansicht von oben eines Brennhilfsmittels in einer weiteren Ausführungsform.

Embodiments of the kiln furniture according to the invention are shown in the following FIGS. 1-15:

• FIG. 1: kiln furniture, first embodiment, top view,
• Figure 2 embodiment and arrangement of the base body in up to the fiber mat in cross section along the line
• Figure 8 II - II in Figure 1,
• FIG. 9 section in a cutting direction rotated by 90 ° with respect to FIG. 2,
• FIG. 10 perspective partial view of a base body,
• FIG. 11 cross section through a firing aid with firing material attached,
• FIG. 12 top view of a field-shaped fiber mat,
• 13 shows a sectional view similar to FIG. 9 through a mat according to FIG. 12 and
• FIG. 14 detail from a top view of a kiln furniture in a further embodiment.

The kiln furniture shown in Figure 1 is formed in several parts and consists of a sheet-like fiber mat 1 made of ceramic fiber material, which can have either a board-like stiff structure or a flexible, flexible structure, so that the fiber mat 1 is elastically deformable to a limited extent. The size of the fiber mat 1 can be adapted to the ceramic product to be fired or the size of the conveyor in the rapid firing furnace. In the exemplary embodiment shown in FIG. 1, the fiber mat 1 is of axially symmetrical design and has a number of depressions 2 in the form of slots or slots, which are arranged and distributed in a straight line, for example in the form of an annular or elongated manner. The wells 2 can extend to a certain depth into the material of the fiber mat 1. In exceptional cases, such a depression can also be provided continuously over the entire thickness of the fiber material (FIG. 4). Base bodies 3 made of fired ceramic material are inserted into the depressions 2, which are rod-like or segment-like, have a relatively simple cross-section (FIGS. 2 to 8), have a small wall thickness and are also relatively short in the direction of the depressions 2. The base body 3 are preferably inserted into the recesses 2 in such a way that they protrude from the surface 4 of the fiber mat 1 and in total form the footprint 5 for the firing material. In the case of a fiber mat 1, all of the depressions 2 do not necessarily have to be occupied by base bodies 3. It is sufficient to choose the trimmings in a way that makes sense and is necessary for putting on the firing material in question. The underside of the fiber mat 1 forms the attachment surface 6, on which the kiln furniture 1, 3 is placed on the conveyor of the rapid firing furnace, for example a trolley or a plate. The fiber mat 1 represents a certain insulation protection for the conveyor of the furnace and forms the basis on which individual base bodies 3 are built and held in a stable position relative to one another, as is necessary for the placement of the firing material.

FIG. 2 shows a simple, rectangular cross section of a base body which is used upright in the recess 2.

Figure 3 shows a U-shaped cross section of a base body 3. The depressions 2 are formed deeper here, so that the base body 3 rests on the surface 4 between the two slot-like depressions 2.

FIG. 4 shows an indentation 2 which is continuous over the thickness of the fiber mat and a base body 3 with a T-shaped cross section, that is to say a profile which he simply extrudes can be fathered.

In the exemplary embodiment in FIG. 5, the base body 3, likewise with a T-shaped cross section, is inserted into the depression 2 such that the installation surface 5 is flush with the surface 4 of the fiber mat 1.

According to the embodiment of Figure 6, the footprint 5 is arranged lower than the surface 4 of the fiber mat. It goes without saying that the exemplary embodiments of FIGS. 5 and 6 are matched to the firing material to be accommodated in such a way that the firing material does not come into contact with the surface 4 of the fiber mat 1.

Figure 7 shows a similar embodiment as Figure 2, but here the base body 3 consists of three individual, flat plates of very small wall thickness, which are set side by side in a bundle in a recess 2.

The kiln furniture according to the embodiment according to FIG. 8 has a fiber mat 1 with a T-groove-shaped undercut recess 2, into which a base body 3 with an I-shaped cross section is inserted. Such an embodiment is particularly useful if a flexible fiber mat 1 is used and the entire kiln furniture is stored, for example by rolling it together, until the corresponding firing material is to be fired again.

As already shown in FIG. 1 and also shown in FIG. 9, the length of the depressions 2 does not necessarily have to match the length of the base body 3. The depressions 2 can rather be longer and can also be provided continuously over the entire width and / or length of the fiber mat 1, so that there is the possibility of using the much shorter base body 3 at any point of the depression 2, namely there where it is needed for the storage of the firing material. Around but also to exclude a displacement of the base body 3 in the direction of the recess 2, the recess 2 can be provided with a shoulder 7 and the base body 3 with one or more knobs 8, so that the base body 3 in the recess 2 is also not in the direction of this recess can slip. FIG. 10 shows the base body according to FIG. 9 again in a perspective representation.

FIG. 12 shows a plan view of a fiber mat 1 in which the entire field of its surface is penetrated by recesses 2 arranged in rows, paragraphs 7 being arranged in a circle in the recesses 2, also in a regular arrangement. In connection with this, base body 3 can be used, as shown in FIG. 13. By relative rotation of 180 ° of the base body 3 before insertion into the recess 2, practically any point in a row of the recess 2 can be occupied with the relevant base body 3. This opens up the possibility of automatically populating the individual rows of the depressions 2 with base bodies 3 and e.g. then set up the respective firing material in a subsequent station. This is particularly possible with rapid firing stoves that are only occupied in one position. Clearing at the end of the furnace can also be automated.

FIG. 11 shows a cross section through an embodiment of this type, in which a plate is placed as the firing material 9.

FIG. 14 shows a section from another exemplary embodiment of the kiln aid from the fiber mat 1 and base bodies 3. Here, intersecting groove sections are provided as depressions 2, into which three base bodies 3 are inserted, so that advantageously a small, light object, for example an egg cup or a cup can be put on as firing stock. The individual base body 3 can additionally in the recesses 2 by a Adhesive 10 be fixed in position.

FIG. 15 shows a cross section through a further embodiment of the kiln furniture, in which the fiber mat 1 is provided with a refractory coating 11, the surface of which forms the footprint 5 for the kiln 9. The coating 11 is interrupted by cuts 12.

B e z u g s z e i c h e n l i s t e:

• 1 = fiber mat
• 2 = deepening
• 3 = basic body
• 4 = surface
• 5 = footprint
• 6 = contact surface
• 7 = paragraph
• 8 = pimples
• 9 = kiln
• 10 = bonding
• 11 = fireproof coating
• 12 = incisions

Claims (10)

1. Kiln furniture for ceramic products to be fired in particular in the rapid firing furnace, consisting of a ceramic base material which has a mounting surface which is in contact with the conveyor of the furnace and has a footprint for the firing material, characterized in that the firing aid is constructed in several parts. 2. Kiln furniture according to claim 1, characterized in that the multi-part kiln furniture consists of an inorganic fiber material forming the contact surface in the form of a binder-free needled fiber mat (blanket) or in the form of a needled fiber mat impregnated with an inorganic binder and from a footprint forming ceramic material in the form of segment-like base body and / or in the form of a refractory coating. 3. Kiln furniture according to claim 1 and 2, characterized in that the kiln furniture is constructed from a fiber mat forming the contact surface and from a plurality of rod-like or segment-like base bodies made of ceramic material, the base bodies being held in a stable position relative to one another in depressions in the fiber mat and overall the Form a space for the fired goods. 4. Kiln furniture according to claim 3, characterized in that the base body made of ceramic material has a cross section that is not susceptible to thermal shock, in particular a rectangular, T-shaped, U-shaped or I-shaped cross section, and has a limited length. 5. Kiln furniture according to claim 3 and 4, characterized in that the base body made of ceramic material with its footprint, the surface of the fiber mat are used outstanding in the fiber mat. 6. Kiln furniture according to claim 3 and 4, characterized in that the fiber mat has a field of optional grooves, slots or other depressions for inserting the base body made of ceramic material. 7. Kiln furniture according to claim 5 and 6, characterized in that paragraphs or openings are provided within the grooves, slots or other depressions and that the base body made of ceramic material have corresponding approaches or knobs. 8. Kiln furniture according to claim 3 and 4, characterized in that the base body made of ceramic material on the fiber mat are attached by gluing. 9. Kiln furniture according to claim 1 and 2, characterized in that the multi-part kiln furniture consists of fiber material based on aluminum oxide and segment-like ceramic base bodies based on silicon carbide, aluminum silicate or aluminum oxide. 10. Kiln furniture according to claim 1 and 2, characterized in that the multi-part kiln furniture consists of fiber material based on aluminum oxide and a refractory coating based on silicon carbide or aluminum oxide.

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