EP0869191A2 - Muffle for heat treating furnace - Google Patents
Muffle for heat treating furnace Download PDFInfo
- Publication number
- EP0869191A2 EP0869191A2 EP98105206A EP98105206A EP0869191A2 EP 0869191 A2 EP0869191 A2 EP 0869191A2 EP 98105206 A EP98105206 A EP 98105206A EP 98105206 A EP98105206 A EP 98105206A EP 0869191 A2 EP0869191 A2 EP 0869191A2
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- EP
- European Patent Office
- Prior art keywords
- muffle
- stainless steel
- products
- ceramic material
- silicon carbide
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 claims abstract description 13
- 229910010271 silicon carbide Inorganic materials 0.000 claims abstract description 13
- 229910001220 stainless steel Inorganic materials 0.000 claims abstract description 13
- 239000010935 stainless steel Substances 0.000 claims abstract description 12
- 229910010293 ceramic material Inorganic materials 0.000 claims abstract description 7
- 238000010438 heat treatment Methods 0.000 claims description 16
- 230000003068 static effect Effects 0.000 claims description 4
- 238000003466 welding Methods 0.000 claims description 4
- 238000000137 annealing Methods 0.000 claims description 3
- 239000000919 ceramic Substances 0.000 claims description 3
- 229910052710 silicon Inorganic materials 0.000 claims description 3
- 239000010703 silicon Substances 0.000 claims description 3
- 238000011282 treatment Methods 0.000 claims description 3
- 229910045601 alloy Inorganic materials 0.000 claims description 2
- 239000000956 alloy Substances 0.000 claims description 2
- 238000001035 drying Methods 0.000 claims description 2
- 229910001092 metal group alloy Inorganic materials 0.000 claims description 2
- 239000010970 precious metal Substances 0.000 claims description 2
- 229910052709 silver Inorganic materials 0.000 claims description 2
- 239000004332 silver Substances 0.000 claims description 2
- 238000005496 tempering Methods 0.000 claims description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims 2
- 229910001260 Pt alloy Inorganic materials 0.000 claims 1
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 claims 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 claims 1
- 239000010931 gold Substances 0.000 claims 1
- 229910052737 gold Inorganic materials 0.000 claims 1
- 239000000377 silicon dioxide Substances 0.000 claims 1
- 230000037431 insertion Effects 0.000 abstract 1
- 238000003780 insertion Methods 0.000 abstract 1
- 238000007669 thermal treatment Methods 0.000 abstract 1
- 239000000463 material Substances 0.000 description 7
- 229910000831 Steel Inorganic materials 0.000 description 6
- 239000010959 steel Substances 0.000 description 6
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 4
- 238000010276 construction Methods 0.000 description 4
- 239000002184 metal Substances 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 description 2
- 238000005219 brazing Methods 0.000 description 2
- 238000004320 controlled atmosphere Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000000446 fuel Substances 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 238000009533 lab test Methods 0.000 description 2
- 238000003754 machining Methods 0.000 description 2
- 238000012423 maintenance Methods 0.000 description 2
- 239000007769 metal material Substances 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 2
- 230000002035 prolonged effect Effects 0.000 description 2
- 230000005855 radiation Effects 0.000 description 2
- 229910001020 Au alloy Inorganic materials 0.000 description 1
- 206010040844 Skin exfoliation Diseases 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000035618 desquamation Effects 0.000 description 1
- 230000005674 electromagnetic induction Effects 0.000 description 1
- 239000003517 fume Substances 0.000 description 1
- 239000003353 gold alloy Substances 0.000 description 1
- 230000006698 induction Effects 0.000 description 1
- 239000011810 insulating material Substances 0.000 description 1
- 230000001788 irregular Effects 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000013528 metallic particle Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 239000001294 propane Substances 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 238000010791 quenching Methods 0.000 description 1
- 230000000171 quenching effect Effects 0.000 description 1
- 238000010583 slow cooling Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000005482 strain hardening Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000002834 transmittance Methods 0.000 description 1
Images
Classifications
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/0043—Muffle furnaces; Retort furnaces
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
- F27B9/00—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity
- F27B9/06—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity heated without contact between combustion gases and charge; electrically heated
- F27B9/062—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity heated without contact between combustion gases and charge; electrically heated electrically heated
- F27B9/063—Resistor heating, e.g. with resistors also emitting IR rays
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
- F27B9/00—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity
- F27B9/06—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity heated without contact between combustion gases and charge; electrically heated
- F27B9/08—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity heated without contact between combustion gases and charge; electrically heated heated through chamber walls
- F27B9/082—Muffle furnaces
- F27B9/084—Muffle furnaces the muffle being fixed and in a single piece
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
- F27B9/00—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity
- F27B9/14—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity characterised by the path of the charge during treatment; characterised by the means by which the charge is moved during treatment
- F27B9/20—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity characterised by the path of the charge during treatment; characterised by the means by which the charge is moved during treatment the charge moving in a substantially straight path tunnel furnace
- F27B9/24—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity characterised by the path of the charge during treatment; characterised by the means by which the charge is moved during treatment the charge moving in a substantially straight path tunnel furnace being carried by a conveyor
- F27B9/243—Endless-strand conveyor
Definitions
- the invention relates to a muffle intended for carrying out treatments according to the preamble of claim 1.
- the machined and work hardened product must therefore be subjected to the action of processes such as the annealing by means of which the reconstruction of the initial crystal lattice is obtained, in giving the material the characteristics of ductility, malleability and the like mechanical and physical properties which it originally possessed and which are necessary so that it can undergo subsequent machining.
- Annealing consists of a prolonged heat treatment, at a temperature high, but less than softening, with subsequent, slow cooling or instantaneous, so as to eliminate internal tensions.
- heat treatment such as, for example, industrial brazing, welding, tempering, enhancement treatment, quenching, drying, case hardening, baking ceramic and other products.
- muffle which consists essentially of the chamber an oven in which the material to be treated is kept isolated from the heat source, consisting of solid, liquid or gaseous fuel, electrical resistances or sources of electromagnetic induction.
- the muffle is then heated indirectly by radiation and convection.
- the mittens are made of stainless steel refractory.
- the mittens constructed of steel stainless refractory are subject to oxidation and flaking phenomena of the metallic material and structural deformation of the body, causing easily imaginable negative economic consequences, since this implies stopping the machine and the need to carry out a maintenance operation for the repair and / or replacement of the mitten itself.
- the oxidation and subsequent flaking of stainless steel constituting the body of the muffle result from the corrosive action of the powder additives which are used in the welding and brazing processes of the objects contained in muffle, as well as that of other chemical components used in heat treatments previously undergone by these objects.
- the effect of thermal jump is remarkable in continuous ovens where the metal mesh conveyor belt on which the objects to be deposited are heat, run the entire length of the muffle chamber.
- the thermal jump in the direction longitudinal which corresponds to the direction of advance of the strip is important, since there is a continuous movement of entry into the muffle of the parts to be treated which are at the room temperature, while the inside of the muffle has a temperature that can be higher than 1100 ° C.
- the object of the invention is to produce a muffle which eliminates the drawbacks cited above.
- this ceramic paste is, thanks to the properties of its components, perfectly stable to unforeseen temperature jumps, even of great amplitude, and totally unassailable by the gases and fumes which emerge in the chamber during the heating heat treatment.
- silicon carbide as a material to constitute the body of the muffle also eliminates the use of the resistance support cage, by providing, advantageously, that the latter are embedded in the thickness of the body cited above; this is made possible by the excellent thermal conductivity of carbide silicon.
- the invention provides that only the lower part of the muffle is made of silicon carbide, while the upper part, less prone to thermal jumps, can remain constructed of steel stainless refractory, as usual, which brings obvious savings financial.
- the invention makes provision not to produce silicon carbide that a base which will be interposed between the lower plane of the muffle, made of stainless steel refractory, and the conveyor belt on which the parts to be heated are placed.
- the muffle comprises a hollow body 1, practically elongated in the direction of advance of the products to be treated, which delimits a chamber 2, inside which the products 4 to be treated are passed thermally continuously on a conveyor belt 3, or else inside which products are statically arranged.
- the body 1 of the muffle is produced with a paste based on ceramic material, especially silicon carbide having a percentage of Si of 82% to 88%.
- the action of the electrical resistors 5, contained in the cage 6, causes the heating of interior chamber 2, the temperature of which is raised to the required value for the heat treatment of the products 4 contained therein; body 1 of the muffle is externally coated with insulating material 6 to prevent heat loss outwards.
- a first possible construction variant provides that the resistors 5 ′ are directly embedded in the body in silicon carbide (see Fig. 3).
- a second construction variant provides that the body of the muffle is partly constructed of silicon carbide 8 and partly of sheet steel stainless refractory 9.
- a third construction variant provides that the body of the muffle is entirely in refractory stainless steel sheet 11, with a base inserted inside 10 for supporting the conveyor belt.
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Mechanical Engineering (AREA)
- Combustion & Propulsion (AREA)
- General Engineering & Computer Science (AREA)
- Crystallography & Structural Chemistry (AREA)
- Thermal Sciences (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Tunnel Furnaces (AREA)
- Heat Treatments In General, Especially Conveying And Cooling (AREA)
Abstract
Description
L'invention se rapporte à un moufle destiné à l'exécution de traitements
thermiques, conforme au préambule de la revendication 1.The invention relates to a muffle intended for carrying out treatments
according to the preamble of
Lorsqu'une matière métallique est soumise à un usinage mécanique, en particulier à froid, elle subit le phénomène bien connu de l'écrouissage, qui provient de la déformation de la disposition cristallographique du réseau, qui rend la matière usinée plus dure et plus fragile et de nature à ne pas se prêter de façon optimale aux éventuels usinages ultérieurs comme le formage, le pliage et d'autres encore.When a metallic material is subjected to mechanical machining, in particularly cold, it undergoes the well-known phenomenon of work hardening, which comes from the deformation of the crystallographic layout of the network, which makes the material machined harder and more fragile and likely not to lend itself optimally to possible further processing such as forming, bending and more.
Le produit usiné et écroui doit donc être soumis à l'action de processus tels que le recuit au moyen duquel on obtient la reconstruction du réseau cristallin initial, en conférant à la matière les caractéristiques de ductilité, malléabilité et les autres propriétés mécaniques et physiques qu'elle possédait à l'origine et qui sont nécessaires pour qu'elle puisse subir les usinages ultérieurs.The machined and work hardened product must therefore be subjected to the action of processes such as the annealing by means of which the reconstruction of the initial crystal lattice is obtained, in giving the material the characteristics of ductility, malleability and the like mechanical and physical properties which it originally possessed and which are necessary so that it can undergo subsequent machining.
Le recuit consiste en un traitement thermique prolongé, à une température élevée, mais inférieure à celle du ramollissement, avec un refroidissement ultérieur, lent ou instantané, de manière à éliminer les tensions internes.Annealing consists of a prolonged heat treatment, at a temperature high, but less than softening, with subsequent, slow cooling or instantaneous, so as to eliminate internal tensions.
D'autres processus industriels prévoient l'utilisation d'un traitement thermique prolongé comme, par exemple, les travaux industriels de soudobrasage, le soudage, le revenu, le traitement d'amélioration, la trempe, le séchage, la cémentation, la cuisson de produits céramiques et d'autres.Other industrial processes include the use of heat treatment such as, for example, industrial brazing, welding, tempering, enhancement treatment, quenching, drying, case hardening, baking ceramic and other products.
Pour effectuer les traitements thermiques prolongés dans les travaux précités, on utilise un équipement appelé moufle qui est constitué essentiellement par la chambre d'un four dans laquelle la matière à traiter est maintenue isolée de la source de chaleur, constituée par un combustible solide, liquide ou gazeux, des résistances électriques ou des sources d'induction électromagnétique.To carry out the extended heat treatments in the aforementioned works, we uses an equipment called muffle which consists essentially of the chamber an oven in which the material to be treated is kept isolated from the heat source, consisting of solid, liquid or gaseous fuel, electrical resistances or sources of electromagnetic induction.
Le chauffage du moufle s'effectue alors indirectement par rayonnement et convection.The muffle is then heated indirectly by radiation and convection.
En fonctionnement, pour réaliser le traitement thermique précité, on fait passer le produit en continu, ou on le dispose de façon statique, dans des moufles de chauffage qu'on dispose à l'intérieur de fours isolés et chauffés indirectement par convection et rayonnement, au moyen de l'énergie fournie par des circuits électriques à résistance ou à induction, placés à l'extérieur du moufle ou au moyen d'un mélange gazeux combustible sortant de brûleurs à propane ou à méthane, qui circule dans des tubes radiants, eux aussi placés extérieurement du moufle précité et sur sa périphérie.In operation, to carry out the aforementioned heat treatment, the continuously produced, or statically arranged, in heating muffles that we have inside insulated ovens and indirectly heated by convection and radiation, by means of the energy supplied by electrical circuits with resistance or induction, placed outside the muffle or by means of a gas mixture fuel coming out of propane or methane burners, which circulates in tubes radiant heaters, also placed on the outside of the abovementioned muffle and on its periphery.
En particulier, pour exécuter des traitements thermiques prolongés dans des fours à cycle continu ou statiques, éventuellement sous atmosphère contrôlée, sur des fils, feuillards, plats, chaínes, lingots, objets divers, en particulier en alliages d'or, d'argent, de platine ou en alliages précieux en général, aussi bien qu'en acier inoxydable et autres alliages métalliques utilisés dans le domaine de l'orfèvrerie, de l'horlogerie, de la bijouterie et de l'industrie des métaux précieux en général, on utilise un moufle de forme parallélépipédique allongée dans le sens horizontal, qui délimite une chambre chauffée au moyen de résistances noyées dans la portion réfractaire du corps du four ou placées extérieurement par rapport au moufle.In particular, to carry out prolonged heat treatments in continuous cycle or static ovens, possibly in a controlled atmosphere, on wires, strips, plates, chains, ingots, various objects, in particular in gold alloys, silver, platinum or precious alloys in general, as well as stainless steel and other metal alloys used in the field of goldsmithery, watchmaking, jewelry and the precious metal industry in general, we use a flask parallelepiped shape elongated in the horizontal direction, which delimits a chamber heated by resistors embedded in the refractory portion of the furnace body, or placed externally with respect to the muffle.
Dans l'état actuel de la technique, les moufles sont réalisés en acier inoxydable réfractaire.In the current state of the art, the mittens are made of stainless steel refractory.
En même temps qu'un bon coefficient de transmission thermique, l'utilisation de l'acier inoxydable réfractaire pour la construction des moufles présente aussi par ailleurs de nombreux inconvénients, qui dépendent spécifiquement des conditions particulières de travail auxquelles le moufle est soumis.In addition to a good thermal transmittance, the use of refractory stainless steel for the construction of mittens also presents many disadvantages, which depend specifically on the particular conditions of work to which the muffle is subjected.
En effet, après une certaine période de travail, les moufles construits en acier inoxydable réfractaire sont sujets à des phénomènes d'oxydation et d'écaillage de la matière métallique et à une déformation structurale du corps, en entraínant des conséquences négatives économiques facilement imaginables, puisque cela implique l'arrêt de la machine et la nécessité de procéder à une opération d'entretien pour la réparation et/ou le remplacement du moufle lui-même.Indeed, after a certain period of work, the mittens constructed of steel stainless refractory are subject to oxidation and flaking phenomena of the metallic material and structural deformation of the body, causing easily imaginable negative economic consequences, since this implies stopping the machine and the need to carry out a maintenance operation for the repair and / or replacement of the mitten itself.
Plus précisément, l'oxydation et l'écaillage consécutif de l'acier inoxydable constituant le corps du moufle résultent de l'action corrosive des additifs en poudre qui sont utilisés dans les procédés de soudage et de soudobrasage des objets contenus dans le moufle, aussi bien que de celle d'autres composants chimiques employés dans les traitements thermiques précédemment subis par ces objets .More specifically, the oxidation and subsequent flaking of stainless steel constituting the body of the muffle result from the corrosive action of the powder additives which are used in the welding and brazing processes of the objects contained in muffle, as well as that of other chemical components used in heat treatments previously undergone by these objects.
Ce phénomène est si intense que, même l'utilisation d'atmosphères contrôlées, protectrices et désoxydantes, introduites à l'intérieur du moufle, ne réussit pas à éliminer cette action de corrosion de la matière, même si elle contribue à la ralentir.This phenomenon is so intense that even the use of controlled atmospheres protective and deoxidizing, introduced inside the muffle, does not succeed in eliminating this corrosion action of the material, even if it helps to slow it down.
L'inconvénient de la déformation structurale, qui peut se développer jusqu'à atteindre à un gauchissement du corps du moufle, consécutif au saut thermique qui se forme entre les diverses zones du corps métallique, entraíne le phénomène précité de 〈〈desquamation〉〉 de l'acier, sous l'effet duquel de minuscules particules métalliques viennent se déposer au-dessus des résistances, en entraínant un défaut de fonctionnement de celles-ci et donc un processus de chauffage irrégulier.The disadvantage of structural deformation, which can develop up to reach a warping of the muffle body, consecutive to the thermal jump which is form between the various areas of the metal body, causes the aforementioned phenomenon of 〈〈Desquamation〉〉 of steel, under the effect of which tiny metallic particles come to settle above the resistances, causing a defect of functioning of these and therefore an irregular heating process.
En particulier, l'effet du saut thermique est remarquable dans les fours continus où la bande transporteuse, à maille métallique, sur laquelle sont déposés les objets à chauffer, parcourt toute la longueur de la chambre du moufle. In particular, the effect of thermal jump is remarkable in continuous ovens where the metal mesh conveyor belt on which the objects to be deposited are heat, run the entire length of the muffle chamber.
Il en résulte que, dans une telle situation, le saut thermique dans la direction longitudinale qui correspond à la direction d'avance de la bande est important, puisqu'il existe un mouvement continu d'entrée dans le moufle des pièces à traiter qui sont à la température ambiante, tandis que l'intérieur du moufle possède une température qui peut être supérieure à 1100°C.As a result, in such a situation, the thermal jump in the direction longitudinal which corresponds to the direction of advance of the strip is important, since there is a continuous movement of entry into the muffle of the parts to be treated which are at the room temperature, while the inside of the muffle has a temperature that can be higher than 1100 ° C.
A la déformation du corps métallique du moufle dans la direction longitudinale, qui résulte du fait qu'on introduit des pièces à la température ambiante (froides), et qu'il en sort des pièces très chaudes, s'ajoute aussi une déformation transversale, c'est-à-dire une déformation de la section du corps qui est due au fait qu'il existe toujours une différence de température entre la base et la voûte du moufle, favorisée par la bande transporteuse qui, devant rester parfaitement plane, circule en appui sur la base de la chambre.To the deformation of the metal body of the muffle in the longitudinal direction, which results from the fact that parts are introduced at room temperature (cold), and that comes out of very hot parts, is also added a transverse deformation, that is to say a deformation of the section of the body which is due to the fact that there is always a temperature difference between the base and the arch of the muffle, favored by the strip conveyor which, having to remain perfectly flat, circulates in abutment on the base of the bedroom.
Le but de l'invention consiste à réaliser un moufle qui élimine les inconvénients précités.The object of the invention is to produce a muffle which eliminates the drawbacks cited above.
Ce but est atteint grâce à un moufle conforme à la partie caractérisante de la
revendication 1.This object is achieved thanks to a muffle conforming to the characterizing part of the
Des formes de réalisation avantageuse de l'invention font l'objet des sous-revendications.Advantageous embodiments of the invention are the subject of the subclaims.
Des essais de laboratoire et des expériences exécutées sur des fours travaillant à diverses températures ont démontré qu'il est satisfaisant d'utiliser un moufle réalisé avec une pâte à base de matière céramique et que, parmi les divers types de cette matière, le plus avantageux s'est révélé être le carbure de silicium, avec un pourcentage de silicium variant entre 82% et 88%.Laboratory tests and experiments performed on furnaces working at various temperatures have demonstrated that it is satisfactory to use a flask made with a paste based on ceramic material and that among the various types of this material, the most advantageous was found to be silicon carbide, with a percentage of silicon varying between 82% and 88%.
En supplément d'une excellente conductibilité thermique et de sa facilité de travail, par moulage ou par coulée, cette pâte céramique est, grâce aux propriétés chimiques de ses composants, parfaitement stable aux sauts imprévus de la température, même de grande amplitude, et totalement inattaquable par les gaz et fumées qui se dégagent dans la chambre pendant le traitement thermique de chauffage.In addition to an excellent thermal conductivity and its ease of work, by molding or by casting, this ceramic paste is, thanks to the properties of its components, perfectly stable to unforeseen temperature jumps, even of great amplitude, and totally unassailable by the gases and fumes which emerge in the chamber during the heating heat treatment.
De cette façon, on réalise des moufles où la stabilité de la matière et l'indéformabilité de la chambre rendent moins fréquentes les coûteuses opérations d'entretien périodique du four, et la bande transporteuse peut circuler dans des conditions optimales, c'est-à-dire en appui sur la base de ladite chambre.In this way, mittens are produced where the stability of the material and the undeformability of the chamber makes costly operations less frequent maintenance of the oven, and the conveyor belt can circulate in optimal conditions, that is to say on the base of said chamber.
L'utilisation du carbure de silicium comme matière pour constituer le corps du moufle permet en outre de supprimer l'utilisation de la cage de support des résistances, en prévoyant, avantageusement, que ces dernières sont noyées dans l'épaisseur du corps précité ; ceci est rendu possible par l'excellente conductibilité thermique du carbure de silicium.The use of silicon carbide as a material to constitute the body of the muffle also eliminates the use of the resistance support cage, by providing, advantageously, that the latter are embedded in the thickness of the body cited above; this is made possible by the excellent thermal conductivity of carbide silicon.
Lorsque les températures de travail ne sont pas trop élevées, l'invention prévoit que seule la partie inférieure du moufle est réalisée en carbure de silicium, tandis que la partie supérieure, moins sujette aux sauts thermiques, peut rester construite en acier inoxydable réfractaire, comme d'habitude, ce qui apporte d'évidentes économies financières.When the working temperatures are not too high, the invention provides that only the lower part of the muffle is made of silicon carbide, while the upper part, less prone to thermal jumps, can remain constructed of steel stainless refractory, as usual, which brings obvious savings financial.
Finalement, toujours pour des raisons économiques et pour pouvoir utiliser les moufles en acier déjà existants, l'invention prévoit de ne réaliser en carbure de silicium qu'une base qui va s'interposer entre le plan inférieur du moufle, en acier inoxydable réfractaire, et la bande transporteuse sur laquelle sont posées les pièces à chauffer.Finally, always for economic reasons and to be able to use the already existing steel mittens, the invention makes provision not to produce silicon carbide that a base which will be interposed between the lower plane of the muffle, made of stainless steel refractory, and the conveyor belt on which the parts to be heated are placed.
Ces caractéristiques de l'invention, ainsi que d'autres; ressortiront plus
clairement de la description d'une forme possible de réalisation, donnée à seul titre
d'exemple illustratif et non limitatif, à l'aide des planches de dessins annexées où :
Comme on peut le voir sur la Fig. 1, le moufle comprend un corps creux 1,
pratiquement de forme allongée dans la direction d'avance des produits à traiter, qui
délimite une chambre 2, à l'intérieur de laquelle on fait passer les produits 4 à traiter
thermiquement en continu sur une bande transporteuse 3, ou bien à l'intérieur de
laquelle les produits sont disposés statiquement.As can be seen in Fig. 1, the muffle comprises a
Selon l'invention, le corps 1 du moufle est réalisé avec une pâte à base de
matière céramique, spécialement de carbure de silicium ayant un pourcentage de Si de
82% à 88%.According to the invention, the
L'action des résistances électriques 5, contenues dans la cage 6, provoque le
chauffage de la chambre intérieure 2, dont la température est portée à la valeur exigée
pour le traitement thermique des produits 4 qui y sont contenus ; le corps 1 du moufle
est revêtu extérieurement d'une matière isolante 6 pour empêcher les pertes de chaleur
vers l'extérieur.The action of the
Une première variante de construction possible prévoit que les résistances 5'
sont directement noyées dans le corps l' en carbure de silicium ( voir Fig. 3). A first possible construction variant provides that the
Une deuxième variante de construction prévoit que le corps du moufle est
construit pour une partie en carbure de silicium 8 et pour une partie en tôle d'acier
inoxydable réfractaire 9.A second construction variant provides that the body of the muffle is
partly constructed of
Une troisième variante de construction prévoit que le corps du moufle est
entièrement en tôle d'acier inoxydable réfractaire 11, avec, insérée à l'intérieur, une base
10 de support de la bande transporteuse.A third construction variant provides that the body of the muffle is
entirely in refractory
Claims (8)
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| ITVI970050 | 1997-03-28 | ||
| IT97VI000050A IT1292971B1 (en) | 1997-03-28 | 1997-03-28 | MUFFLE TO CARRY OUT HEAT TREATMENTS |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| EP0869191A2 true EP0869191A2 (en) | 1998-10-07 |
| EP0869191A3 EP0869191A3 (en) | 2000-10-04 |
Family
ID=11426316
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP98105206A Withdrawn EP0869191A3 (en) | 1997-03-28 | 1998-03-23 | Muffle for heat treating furnace |
Country Status (2)
| Country | Link |
|---|---|
| EP (1) | EP0869191A3 (en) |
| IT (1) | IT1292971B1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106403583A (en) * | 2016-10-31 | 2017-02-15 | 洛阳索莱特材料科技有限公司 | Composite hearth of muffle furnace |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR1100782A (en) * | 1954-05-19 | 1955-09-23 | Furnace for metallurgical treatments | |
| CH520909A (en) * | 1970-03-11 | 1972-03-31 | Electrozone Yverdon S A | Gas-fired tunnel kiln - with circular tunnel continuous belt conveyor and internal protective gas generator |
| DE2217271A1 (en) * | 1972-04-11 | 1973-10-31 | Koppers Gmbh Heinrich | METHOD FOR MANUFACTURING A FOR ERECTION OR LINING OF MUFFLED OVENS, IN PARTICULAR COOK OVEN, SUITABLE SILICON CARBIDE STONES |
| GB2072313A (en) * | 1980-03-26 | 1981-09-30 | Fhd Furnaces Ltd | Muffle furnace |
| FR2658276A3 (en) * | 1990-02-09 | 1991-08-16 | Siderurgie Fse Inst Rech | Device for localised reheating of metallurgical products moving past |
| JPH03260591A (en) * | 1990-03-08 | 1991-11-20 | O S Seramu Kk | Continuous sintering furnace |
-
1997
- 1997-03-28 IT IT97VI000050A patent/IT1292971B1/en active IP Right Grant
-
1998
- 1998-03-23 EP EP98105206A patent/EP0869191A3/en not_active Withdrawn
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR1100782A (en) * | 1954-05-19 | 1955-09-23 | Furnace for metallurgical treatments | |
| CH520909A (en) * | 1970-03-11 | 1972-03-31 | Electrozone Yverdon S A | Gas-fired tunnel kiln - with circular tunnel continuous belt conveyor and internal protective gas generator |
| DE2217271A1 (en) * | 1972-04-11 | 1973-10-31 | Koppers Gmbh Heinrich | METHOD FOR MANUFACTURING A FOR ERECTION OR LINING OF MUFFLED OVENS, IN PARTICULAR COOK OVEN, SUITABLE SILICON CARBIDE STONES |
| GB2072313A (en) * | 1980-03-26 | 1981-09-30 | Fhd Furnaces Ltd | Muffle furnace |
| FR2658276A3 (en) * | 1990-02-09 | 1991-08-16 | Siderurgie Fse Inst Rech | Device for localised reheating of metallurgical products moving past |
| JPH03260591A (en) * | 1990-03-08 | 1991-11-20 | O S Seramu Kk | Continuous sintering furnace |
Non-Patent Citations (1)
| Title |
|---|
| PATENT ABSTRACTS OF JAPAN vol. 016, no. 072 (M-1213), 21 février 1992 (1992-02-21) & JP 03 260591 A (O S SERAMU KK;OTHERS: 01), 20 novembre 1991 (1991-11-20) * |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106403583A (en) * | 2016-10-31 | 2017-02-15 | 洛阳索莱特材料科技有限公司 | Composite hearth of muffle furnace |
Also Published As
| Publication number | Publication date |
|---|---|
| ITVI970050A0 (en) | 1997-03-28 |
| EP0869191A3 (en) | 2000-10-04 |
| ITVI970050A1 (en) | 1998-09-28 |
| IT1292971B1 (en) | 1999-02-11 |
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