WO2013159230A1 - Conveyor system for a high-frequency furnace - Google Patents

Conveyor system for a high-frequency furnace Download PDF

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Publication number
WO2013159230A1
WO2013159230A1 PCT/CA2013/050317 CA2013050317W WO2013159230A1 WO 2013159230 A1 WO2013159230 A1 WO 2013159230A1 CA 2013050317 W CA2013050317 W CA 2013050317W WO 2013159230 A1 WO2013159230 A1 WO 2013159230A1
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WO
WIPO (PCT)
Prior art keywords
belt
conveyor system
metal
insulating material
electrically insulating
Prior art date
Application number
PCT/CA2013/050317
Other languages
French (fr)
Inventor
James Kendall
Sylvain CHÉNARD
Original Assignee
HYDRO-QUéBEC
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Application filed by HYDRO-QUéBEC filed Critical HYDRO-QUéBEC
Publication of WO2013159230A1 publication Critical patent/WO2013159230A1/en

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B15/00—Machines or apparatus for drying objects with progressive movement; Machines or apparatus with progressive movement for drying batches of material in compact form
    • F26B15/10—Machines or apparatus for drying objects with progressive movement; Machines or apparatus with progressive movement for drying batches of material in compact form with movement in a path composed of one or more straight lines, e.g. compound, the movement being in alternate horizontal and vertical directions
    • F26B15/12—Machines or apparatus for drying objects with progressive movement; Machines or apparatus with progressive movement for drying batches of material in compact form with movement in a path composed of one or more straight lines, e.g. compound, the movement being in alternate horizontal and vertical directions the lines being all horizontal or slightly inclined
    • F26B15/18—Machines or apparatus for drying objects with progressive movement; Machines or apparatus with progressive movement for drying batches of material in compact form with movement in a path composed of one or more straight lines, e.g. compound, the movement being in alternate horizontal and vertical directions the lines being all horizontal or slightly inclined the objects or batches of materials being carried by endless belts
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B3/00—Drying solid materials or objects by processes involving the application of heat
    • F26B3/32—Drying solid materials or objects by processes involving the application of heat by development of heat within the materials or objects to be dried, e.g. by fermentation or other microbiological action
    • F26B3/34—Drying solid materials or objects by processes involving the application of heat by development of heat within the materials or objects to be dried, e.g. by fermentation or other microbiological action by using electrical effects
    • F26B3/347—Electromagnetic heating, e.g. induction heating or heating using microwave energy

Definitions

  • the invention generally relates to a conveyor system for a high frequency furnace, and more particularly to a conveyor belt system for moving products between upper and lower electrode structures of a high frequency furnace. STATE OF THE ART
  • High frequency furnaces e.g. 1 MHz to 500 MHz or higher, are used in many applications to heat, dry or thaw various products, for example, food products, wood, polymer sheets, etc.
  • High frequency kilns are often equipped with conveyor systems to route products through kilns, especially at the industrial level.
  • An object of the present invention is to provide a conveyor belt system for high frequency furnace which reduces the risk of electric arcs and external radiation.
  • Another object of the invention is to provide such a conveyor system for high frequency furnace which is potentially more mechanically strong and less susceptible to breakage due to arcing than current conveyor systems for high frequency furnaces.
  • a conveyor system for moving products between upper and lower electrode structures of a high frequency furnace comprising:
  • a flexible metal belt for receiving the products to be moved in the high frequency furnace and forming a continuous band, the metal belt having a section extending between the electrode structures of the high frequency furnace;
  • a belt support having an elongated metal upper portion in a direction of movement of the products in the high frequency furnace and forming part of the lower electrode structure of the high frequency furnace, and a layer of electrically insulating material resistant to abrasion and to the electrical arcs, extending over the upper part and on which the section of the belt slides, the section of the belt, the metallic upper part and the layer of electrically insulating material forming a capacitive effect arrangement conducive to a transfer of high-frequency current.
  • Figure 1 is a schematic diagram showing a high frequency furnace with a conveyor system according to the invention.
  • Figures 2A, 2B, 2C and 2D are schematic diagrams showing possible configurations of metal belt according to the invention, seen from above.
  • Figures 3A, 3B, 3C, 3D and 3E are schematic diagrams showing possible configurations of belt support according to the invention, seen from above.
  • Figures 4A and 4B are schematic diagrams showing possible configurations of a conveyor system for high frequency furnace according to the invention, seen from the side.
  • the term "oven” refers to both an oven and a dryer or other similar device for heating, drying, or thawing one or more products.
  • FIG. 1 there is shown a high frequency furnace 2 with a conveyor system 4 according to the invention.
  • the products 6 to be treated enter an enclosure 8 of the high-frequency furnace 2 and emerge via wave traps 10, 12, in a direction of displacement represented by the arrows 14, 16.
  • the conveyor system 4 makes it possible to move the products 6 between the upper electrode 18 and lower 20 electrode structures of the high frequency furnace 2.
  • the conveyor system 4 may extend beyond the limits of the high frequency furnace 2 if desired.
  • the upper electrode structure 18 is connected to a high frequency generator 22 of the high frequency furnace 2
  • the lower electrode structure 20 is connected to the ground 24.
  • the reverse is also possible.
  • the conveyor system 4 comprises a flexible metal belt 26 for receiving the products 6 to be moved in the high frequency furnace 2 and forming a continuous band.
  • the metal belt has a section extending between the electrode structures 18, 20 of the high frequency furnace 2, where the products disposed on the belt are exposed to the radiation of the furnace when in operation.
  • the section is defined as the section of the belt 26 which extends roughly between end rollers 28, 30 of the conveyor system 4. In the case where the conveyor system 4 exceeds the limits of the furnace 2, then the section would then be defined as being located inside the furnace, between the electrode structures 18, 20.
  • the upper electrode structure has the shape of a plate of metal.
  • the upper electrode structure may take other forms and be of any suitable conductive material to produce high frequency electromagnetic radiation if desired, such as a series of bars (not shown) spaced from each other in the direction of the moving the products 6 in the furnace 2.
  • the return path of the belt 26, in the opposite direction of displacement of the products 6, can pass through the high frequency furnace 2 as illustrated, or be outside the high frequency furnace 2 if wanted.
  • the conveyor system 4 also includes a belt support 32.
  • the belt support 32 has a metal upper portion 34 elongate in the direction of movement 14, 16 of the products 6 in the high frequency furnace 2 and making part of the lower electrode structure 20 of the high frequency furnace 2.
  • the belt support 32 also has a layer of electrically insulating material 36 resistant to abrasion and arcing, extending over the upper portion 34 and which section of the belt 26 slides.
  • the belt support 32 extends from one wave trap 10 to the other wave trap 12.
  • the section of the belt 26, the metal top 34 and the layer of electrically insulating material 36 form a capacitive-effect arrangement conducive to high-frequency current transfer.
  • the belt 26 is preferably made of paramagnetic or diamagnetic metal, such as 300 series austenitic stainless steel, to limit heating of the belt 26 in the presence of high frequency electromagnetic radiation.
  • the belt 26 preferably has substantially smooth lower and upper surfaces, as shown in FIG. 2D, also helping to limit the occurrence of arcs as compared to a mesh or staple belt articulated to each other when exposed to strong electromagnetic fields.
  • the belt 26 may, if necessary, be perforated as shown in Figures 2A, 2B and 2C, to allow evacuation of water or water vapor from below.
  • the belt then has perforations 38 distributed along the belt 26, preferably forming a regular pattern along the belt 26.
  • the perforations 38 may be in the form of holes as shown in FIG. 2A, with successive slots perpendicular to the the direction of movement of the belt 26 as shown in FIG. 2B, rows of alternating slots in the direction of movement of the belt 26 as shown in FIG. 2C, or any other arrangement and shape of perforations having no incidence significant on the conductive surface of the belt section 26 between the electrode structures 18, 20 (illustrated in FIG. 1).
  • the belt support 32 may be an integral part of the high frequency furnace 2.
  • the belt support 32 acts as a high frequency energy transfer structure to the belt 26, either being energized when connected directly or indirectly to the output of the high frequency generator 22, that is to the ground 24 (which is preferable) with the structure surrounding the treatment area of the high frequency furnace 2.
  • the belt support 32 also acts as a sliding surface for the metal strap 26.
  • the metal upper portion 34 is electrically conductive, so that the layer of electrically insulating material 36 is found between the metal upper portion 34 and the metal belt 26 both electrically conductive.
  • the layer of electrically insulating material 36 completely covers an upper surface of the metallic upper portion 34, otherwise at least a portion of the upper surface capable of being in contact with the belt section 26 between the electrode structures 18, 20.
  • the belt support 32 may comprise an arrangement 40 having a certain rigidity or conferring mechanical properties specific to the belt support 32, for example to provide support for the metal upper portion 34 when it is thin or in an insufficiently rigid material and provide additional mechanical strength if desired or necessary.
  • the metallic upper part 34 is preferably made of paramagnetic or diamagnetic metal, such as for example aluminum, an aluminum alloy, copper, brass and stainless steels of series 300.
  • the upper part 34 may take the form of a plate as shown in Figure 3D.
  • the upper portion 34 may also take the form of successive segments spaced from each other in the direction of movement of the products 6, as shown in Figure 3E.
  • the segments preferably have widths substantially greater than spacing distances between the segments, so that the contact area between the belt support 32 and the belt section 26 between the electrode structures 18, 20 is the possible gradients and potentials gradients are the lowest possible to limit the risks of radiation to the outside of the treatment area of the high frequency furnace 2, for example via the wave traps 10, 12.
  • the layer of electrically insulating material 36 and the belt section 26 between the electrode structures 18, 20 have contact areas whose total area promotes a high frequency current flow, for example a total area of at least 0.1 m 2 where the high frequency current flows, or according to the maximum effective impedance targeted.
  • the layer of electrically insulating material 36 preferably has a coefficient of friction promoting a sliding of the flexible metal belt 26.
  • the layer of electrically insulating material 36 may be made of a material such as, for example, boron nitride and aluminum oxide. (hard anodized aluminum). The aluminum oxide may be impregnated with Teflon particles to reduce friction with the belt 26 and increase the wear resistance of the layer of electrically insulating material 36.
  • the layer of insulating material 36 may be applied to the metal upper part 34 as a coating or by another surface covering method, or also depending, depending on the material constituting the metal upper part 34, a process such as a chemical vapor deposition (or CVD for "chemical vapor deposition ”) or hard anodizing or other similar surface treatment.
  • a chemical vapor deposition or CVD for "chemical vapor deposition ”
  • hard anodizing or other similar surface treatment.
  • the metallic upper portion 34 and the layer of electrically insulating material 36 may have common perforations 42 distributed along the belt support 32.
  • the flexible metal belt 26 and the portion metallic upper 34 are made of a material with low magnetic permeability and high electrical conductivity with respect to the layer of electrically insulating material 36.
  • Figures 4A and 4B it is shown other possible configurations of a conveyor system 4 for high frequency furnace according to the invention, particularly suitable, for example, for heating or drying a product in the form of film or web. Rather than a linear configuration as shown in Figure 1, the conveyor system 4 may have a configuration where the treatment area describes a curve.
  • the electrode structure 18 has a concave face within which an end roller of the conveyor system 4, acting as belt support 32, engages.
  • Figure 4A shows a configuration where the upper part metal 34 covered with the layer of electrically insulating material 36 is formed by the periphery of the end roller and connected to the high frequency generator 22 (shown in Figure 1) while the electrode structure 18 is connected to ground.
  • Figure 4B shows a similar configuration but where the electrode structure 18 is connected to the generator 22 while the metal top 34 is connected to ground.
  • the belt / belt support assembly 32 is preferably designed to provide an impedance value for the flow of currents at the lowest possible generator operating frequency.
  • the layer of electrically insulating material 36 is as thin as possible, or the contact area between the section of the belt 26 at the metal top 34 is as large as possible.
  • a layer of electrically insulating material 36 obtained by hard surface anodization of an aluminum alloy plate forming the upper metallic part 34 could have a thickness of between 5 and 150 microns.
  • a belt 26 made of stainless steel 300 series could have a thickness of 0.2 mm to 3 mm.
  • the thickness of the alumina layer resulting from the anodization may be (it is not an exact science) about 2 times thicker than metal "eaten" during anodization.
  • an upper portion 34 of aluminum has been reduced to a thickness of 5 microns since the alumina comes from the aluminum subjected to the anodizing process.
  • the volume density of aluminum is about 2 times greater than the alumina layer.
  • the aluminum should therefore initially have preferably the same thickness as the desired alumina layer (half of the aluminum initially available is converted into alumina).
  • type I, type II and type II I type II is preferred because it is more resistant to abrasion than the others. It should be noted that for other types of materials, for example Teflon coated silver, other considerations may be involved.
  • the conveyor system 4 can be used for various applications having a combination of the following characteristics: using heating or drying by high frequency; conveying materials through a high frequency furnace; conveying materials not compatible with polymers; energy application electrodes having a large area (eg of capacitive shape); products to be heated requiring a temperature of more than 100 ° C; high power density; high risk for arcing.
  • the conveyor system 4 is particularly useful in the field of wood drying with a high frequency drying equipment such as that shown in the application WO 2009/006737 (Kendall et al.).
  • the conveyor system 4 can also be used for heating applications, drying or thawing food products by high frequency continuously.
  • the use of a smooth stainless steel belt 26 allows the development of applications requiring food grade equipment, for example certain pharmaceutical products.

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  • General Engineering & Computer Science (AREA)
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Abstract

The invention relates to a conveyor system for moving products between upper and lower electrode structures of a high-frequency furnace. A flexible metal belt for receiving the products to be moved in the furnace forms a continuous belt. A section of the metal belt extends between the electrode structures of the furnace. A belt carrier has an upper metal portion extending in a direction of movement of the products in the furnace and is part of the lower electrode structure of the furnace. A layer of an electrically insulating material which is resistant to wear and electric arcs and on which the section of the belt slides extends over the upper portion. The section of the belt, the upper metal portion, and the layer of electrically insulating material form an arrangement which has a capacitive effect and which is suitable for transferring a high-frequency current.

Description

SYSTÈME CONVOYEUR POUR FOUR HAUTE FRÉQUENCE  CONVEYOR SYSTEM FOR HIGH FREQUENCY OVEN
DOMAINE DE L'INVENTION L'invention porte en général sur un système convoyeur pour four haute fréquence, et plus particulièrement sur un système convoyeur à courroie métallique pour déplacer des produits entre des structures d'électrodes supérieure et inférieure d'un four haute fréquence. ÉTAT DE LA TECHNIQUE FIELD OF THE INVENTION The invention generally relates to a conveyor system for a high frequency furnace, and more particularly to a conveyor belt system for moving products between upper and lower electrode structures of a high frequency furnace. STATE OF THE ART
Les fours haute fréquence, e.g. 1 MHz à 500 MHz ou plus, sont utilisés dans de nombreuses applications pour chauffer, sécher ou décongeler des produits de diverses natures, par exemple des produits alimentaires, du bois, des feuilles en polymère, etc. Les fours haute fréquence sont souvent équipés de systèmes convoyeurs pour acheminer les produits à travers les fours, en particulier au niveau industriel. High frequency furnaces, e.g. 1 MHz to 500 MHz or higher, are used in many applications to heat, dry or thaw various products, for example, food products, wood, polymer sheets, etc. High frequency kilns are often equipped with conveyor systems to route products through kilns, especially at the industrial level.
Les brevets US 2,807,699 (Moore), US 4,682,927 (Southworth et al.), US 4,890,394 (Troetscher), US 6,080,978 (Blaker et al.), US 6,914,226 (Ottaway), US 7, 183,527 (Germain et al.), US 7,222,727 (Aisenbrey) et US 7,927,465 (Novak) montrent des exemples de fours haute fréquence avec systèmes convoyeurs. Les systèmes convoyeurs dotés d'une courroie métallique à mailles ou en plaques ou panneaux articulés les uns aux autres ont l'avantage de réduire les risques de contamination des produits à traiter comparativement aux systèmes convoyeurs à courroie en polymère ou fibre de verre. Ils ont aussi l'avantage de permettre l'utilisation de densités de puissance plus élevée. Par contre, les risques d'arcs électriques dangereux et dommageables pour les pièces du système convoyeur et du four haute fréquence, et les risques de rayonnement indésirable à l'extérieure du four, peuvent être plus élevés dans le cas des systèmes convoyeurs à courroie métallique. SOMMAIRE US Patents 2,807,699 (Moore), US 4,682,927 (Southworth et al.), US 4,890,394 (Troetscher), US 6,080,978 (Blaker et al.), US 6,914,226 (Ottaway), US 7,183,527 (Germain et al.), US 7,222,727 (Aisenbrey) and US 7,927,465 (Novak) show examples of high frequency furnaces with conveyor systems. Conveyor systems equipped with a metal mesh belt or articulated plates or panels have the advantage of reducing the risk of contamination of the products to be treated compared to polymer or fiberglass belt conveyor systems. They also have the advantage of allowing the use of higher power densities. On the other hand, the risk of dangerous and damaging electric arcs for the parts of the conveyor system and the high frequency furnace, and the risks of unwanted radiation outside the furnace, may be higher in the case of conveyor belt systems. . SUMMARY
Un objet de la présente invention est de proposer un système convoyeur à courroie métallique pour four haute fréquence qui réduit les risques d'arcs électriques et de rayonnement extérieur. An object of the present invention is to provide a conveyor belt system for high frequency furnace which reduces the risk of electric arcs and external radiation.
Un autre objet de l'invention est de proposer un tel système convoyeur pour four haute fréquence qui est potentiellement plus résistant mécaniquement et moins susceptibles à des bris dus à des arcs électriques que les systèmes convoyeurs actuels pour fours haute fréquence. Another object of the invention is to provide such a conveyor system for high frequency furnace which is potentially more mechanically strong and less susceptible to breakage due to arcing than current conveyor systems for high frequency furnaces.
Selon un aspect de l'invention, il est proposé un système convoyeur pour déplacer des produits entre des structures d'électrodes supérieure et inférieure d'un four haute fréquence, le système convoyeur comprenant: According to one aspect of the invention, there is provided a conveyor system for moving products between upper and lower electrode structures of a high frequency furnace, the conveyor system comprising:
une courroie métallique flexible destinée à recevoir les produits à déplacer dans le four haute fréquence et formant une bande continue, la courroie métallique ayant une section s'étendant entre les structures d'électrodes du four haute fréquence; et  a flexible metal belt for receiving the products to be moved in the high frequency furnace and forming a continuous band, the metal belt having a section extending between the electrode structures of the high frequency furnace; and
un support de courroie ayant une partie supérieure métallique allongée dans une direction de déplacement des produits dans le four haute fréquence et faisant partie de la structure d'électrodes inférieure du four haute fréquence, et une couche de matériau électriquement isolant résistant à l'abrasion et à des arcs électriques, s'étendant sur la partie supérieure et sur laquelle la section de la courroie glisse, la section de la courroie, la partie supérieure métallique et la couche de matériau électriquement isolant formant un arrangement à effet capacitif propice à un transfert de courant haute-fréquence.  a belt support having an elongated metal upper portion in a direction of movement of the products in the high frequency furnace and forming part of the lower electrode structure of the high frequency furnace, and a layer of electrically insulating material resistant to abrasion and to the electrical arcs, extending over the upper part and on which the section of the belt slides, the section of the belt, the metallic upper part and the layer of electrically insulating material forming a capacitive effect arrangement conducive to a transfer of high-frequency current.
DESCRIPTION BRÈVE DES DESSI NS BRIEF DESCRIPTION OF DESSI NS
Une description détaillée des réalisations préférées de l'invention sera donnée ci-après en référence avec les dessins suivants: Figure 1 est un diagramme schématique montrant un four haute fréquence avec un système convoyeur selon l'invention. A detailed description of the preferred embodiments of the invention will be given hereinafter with reference to the following drawings: Figure 1 is a schematic diagram showing a high frequency furnace with a conveyor system according to the invention.
Figures 2A, 2B, 2C et 2D sont des diagrammes schématiques montrant des configurations possibles de courroie métallique selon l'invention, vues de dessus. Figures 2A, 2B, 2C and 2D are schematic diagrams showing possible configurations of metal belt according to the invention, seen from above.
Figures 3A, 3B, 3C, 3D et 3E sont des diagrammes schématiques montrant des configurations possibles de support de courroie selon l'invention, vues de dessus. Figures 3A, 3B, 3C, 3D and 3E are schematic diagrams showing possible configurations of belt support according to the invention, seen from above.
Figures 4A et 4B sont des diagrammes schématiques montrant des configurations possibles d'un système convoyeur pour four haute fréquence selon l'invention, vues de côté. Figures 4A and 4B are schematic diagrams showing possible configurations of a conveyor system for high frequency furnace according to the invention, seen from the side.
DESCRIPTION DÉTAILLÉE DES RÉALISATIONS PRÉFÉRÉES DETAILED DESCRIPTION OF PREFERRED ACHIEVEMENTS
Tel qu'utilisé dans le cadre de cette divulgation, le terme "four " désigne autant un four qu'un séchoir ou autre dispositif semblable servant à chauffer, sécher, ou décongeler un ou des produits. As used in this disclosure, the term "oven" refers to both an oven and a dryer or other similar device for heating, drying, or thawing one or more products.
En référence à la Figure 1 , il est montré un four haute fréquence 2 avec un système convoyeur 4 selon l'invention. Les produits 6 à traiter entrent dans une enceinte 8 du four haute fréquence 2 et en ressortent via des pièges d'onde 10, 12, dans une direction de déplacement représentée par les flèches 14, 16. Le système convoyeur 4 permet de déplacer les produits 6 entres des structures d'électrodes supérieure 18 et inférieure 20 du four haute fréquence 2. Le système convoyeur 4 peut s'étendre au-delà des limites du four haute fréquence 2 si voulu. Dans le cas illustré, la structure d'électrode supérieure 18 est reliée à un générateur haute fréquence 22 du four haute fréquence 2, et la structure d'électrode inférieure 20 est reliée à la masse 24. L'inverse est aussi possible. Le système convoyeur 4 comprend une courroie métallique flexible 26 destinée à recevoir les produits 6 à déplacer dans le four haute fréquence 2 et formant une bande continue. La courroie métallique a une section s'étendant entre les structures d'électrodes 18, 20 du four haute fréquence 2, où les produits disposés sur la courroie sont exposés au rayonnement du four lorsqu'il est en opération. Dans le cas illustré, la section est définie comme étant la section de la courroie 26 qui s'étend grosso modo entre des rouleaux d'extrémité 28, 30 du système convoyeur 4. Dans le cas où le système convoyeur 4 dépasserait les limites du four 2, alors la section serait alors définie comme étant celle qui est située à l'intérieur du four, entre les structures d'électrodes 18, 20. Dans le cas illustré, la structure d'électrodes supérieure a la forme d'une plaque de métal. La structure d'électrodes supérieure peut prendre d'autres formes et être en n'importe quel matériau conducteur approprié pour produire un rayonnement électromagnétique haute fréquence si voulu, comme une série de barres (non illustrées) espacées les unes des autres dans le sens du déplacement des produits 6 dans le four 2. Le chemin de retour de la courroie 26, dans la direction inverse de déplacement des produits 6, peut passer à travers le four haute fréquence 2 comme illustré, ou être à l'extérieur du four haute fréquence 2 si voulu. Referring to Figure 1, there is shown a high frequency furnace 2 with a conveyor system 4 according to the invention. The products 6 to be treated enter an enclosure 8 of the high-frequency furnace 2 and emerge via wave traps 10, 12, in a direction of displacement represented by the arrows 14, 16. The conveyor system 4 makes it possible to move the products 6 between the upper electrode 18 and lower 20 electrode structures of the high frequency furnace 2. The conveyor system 4 may extend beyond the limits of the high frequency furnace 2 if desired. In the illustrated case, the upper electrode structure 18 is connected to a high frequency generator 22 of the high frequency furnace 2, and the lower electrode structure 20 is connected to the ground 24. The reverse is also possible. The conveyor system 4 comprises a flexible metal belt 26 for receiving the products 6 to be moved in the high frequency furnace 2 and forming a continuous band. The metal belt has a section extending between the electrode structures 18, 20 of the high frequency furnace 2, where the products disposed on the belt are exposed to the radiation of the furnace when in operation. In the case illustrated, the section is defined as the section of the belt 26 which extends roughly between end rollers 28, 30 of the conveyor system 4. In the case where the conveyor system 4 exceeds the limits of the furnace 2, then the section would then be defined as being located inside the furnace, between the electrode structures 18, 20. In the illustrated case, the upper electrode structure has the shape of a plate of metal. The upper electrode structure may take other forms and be of any suitable conductive material to produce high frequency electromagnetic radiation if desired, such as a series of bars (not shown) spaced from each other in the direction of the moving the products 6 in the furnace 2. The return path of the belt 26, in the opposite direction of displacement of the products 6, can pass through the high frequency furnace 2 as illustrated, or be outside the high frequency furnace 2 if wanted.
Le système convoyeur 4 comprend aussi un support de courroie 32. Tel que mieux vu en agrandi, le support de courroie 32 a une partie supérieure métallique 34 allongée dans la direction de déplacement 14, 16 des produits 6 dans le four haute fréquence 2 et faisant partie de la structure d'électrodes inférieure 20 du four haute fréquence 2. Le support de courroie 32 a également une couche de matériau électriquement isolant 36 résistant à l'abrasion et à des arcs électriques, s'étendant sur la partie supérieure 34 et sur laquelle la section de la courroie 26 glisse. De préférence, le support de courroie 32 s'étend d'un piège d'onde 10 à l'autre piège d'onde 12. The conveyor system 4 also includes a belt support 32. As best seen enlarged, the belt support 32 has a metal upper portion 34 elongate in the direction of movement 14, 16 of the products 6 in the high frequency furnace 2 and making part of the lower electrode structure 20 of the high frequency furnace 2. The belt support 32 also has a layer of electrically insulating material 36 resistant to abrasion and arcing, extending over the upper portion 34 and which section of the belt 26 slides. Preferably, the belt support 32 extends from one wave trap 10 to the other wave trap 12.
La section de la courroie 26, la partie supérieure métallique 34 et la couche de matériau électriquement isolant 36 forment un arrangement à effet capacitif propice à un transfert de courant haute-fréquence. La courroie 26 est de préférence faite en métal paramagnétique ou diamagnétique, comme par exemple un acier inoxydable austénitique de série 300, afin de limiter réchauffement de la courroie 26 en présence de rayonnement électromagnétique haute fréquence. La courroie 26 a de préférence des surfaces inférieure et supérieure sensiblement lisses, comme illustré à la Figure 2D, contribuant aussi à limiter l'occurrence d'arcs comparativement à une courroie à mailles ou à pièces discontinues articulées les unes aux autres lorsqu'exposée à de forts champs électromagnétiques. The section of the belt 26, the metal top 34 and the layer of electrically insulating material 36 form a capacitive-effect arrangement conducive to high-frequency current transfer. The belt 26 is preferably made of paramagnetic or diamagnetic metal, such as 300 series austenitic stainless steel, to limit heating of the belt 26 in the presence of high frequency electromagnetic radiation. The belt 26 preferably has substantially smooth lower and upper surfaces, as shown in FIG. 2D, also helping to limit the occurrence of arcs as compared to a mesh or staple belt articulated to each other when exposed to strong electromagnetic fields.
La courroie 26, et plus particulièrement la section de courroie à l'intérieur du four 2, agit comme électrode haute fréquence à potentiel flottant. The belt 26, and more particularly the belt section inside the furnace 2, acts as a floating potential high frequency electrode.
La courroie 26 peut, au besoin, être perforée comme illustré aux Figures 2A, 2B et 2C, afin de permettre une évacuation d'eau ou de vapeur d'eau par en dessous. La courroie comporte alors des perforations 38 réparties le long de la courroie 26, formant de préférence un motif régulier le long de la courroie 26. Les perforations 38 peuvent être sous forme de trous comme montré à la figure 2A, de fentes successives perpendiculaires à la direction de déplacement de la courroie 26 comme montré à la Figure 2B, de rangées de fentes alternées dans la direction de déplacement de la courroie 26 comme montré à la Figure 2C, ou tout autre arrangement et forme de perforations n'ayant pas d'incidence significative sur la superficie conductrice de la section de courroie 26 entre les structures d'électrodes 18, 20 (illustrées à la Figure 1 ). The belt 26 may, if necessary, be perforated as shown in Figures 2A, 2B and 2C, to allow evacuation of water or water vapor from below. The belt then has perforations 38 distributed along the belt 26, preferably forming a regular pattern along the belt 26. The perforations 38 may be in the form of holes as shown in FIG. 2A, with successive slots perpendicular to the the direction of movement of the belt 26 as shown in FIG. 2B, rows of alternating slots in the direction of movement of the belt 26 as shown in FIG. 2C, or any other arrangement and shape of perforations having no incidence significant on the conductive surface of the belt section 26 between the electrode structures 18, 20 (illustrated in FIG. 1).
En référence à nouveau à la Figure 1 , le support de courroie 32 peut faire partie intégrante du four haute fréquence 2. Le support de courroie 32 agit comme structure de transfert d'énergie haute fréquence à la courroie 26, en étant soit sous tension lorsque branché directement ou indirectement à la sortie du générateur haute fréquence 22, soit à la masse 24 (ce qui est préférable) avec la structure entourant la zone de traitement du four haute fréquence 2. Le support de courroie 32 agit également comme surface de glissement pour la courroie métallique 26. La partie supérieure métallique 34 est conductrice d'électricité, de sorte que la couche de matériau électriquement isolant 36 se retrouve entre la partie supérieure métallique 34 et la courroie métallique 26 toutes deux électriquement conductrices. De préférence, la couche de matériau électriquement isolant 36 recouvre au complet une surface supérieure de la partie supérieure métallique 34, sinon au moins une partie de la surface supérieure susceptible d'être en contact avec la section de courroie 26 entre les structures d'électrodes 18, 20. Le support de courroie 32 peut comporter un arrangement 40 ayant une certaine rigidité ou conférant des propriétés mécaniques spécifiques au support de courroie 32, par exemple pour fournir un soutien à la partie supérieure métallique 34 lorsque celle-ci est de faible épaisseur ou en un matériau insuffisamment rigide et procurer une tenue mécanique supplémentaire si désiré ou nécessaire. Referring back to FIG. 1, the belt support 32 may be an integral part of the high frequency furnace 2. The belt support 32 acts as a high frequency energy transfer structure to the belt 26, either being energized when connected directly or indirectly to the output of the high frequency generator 22, that is to the ground 24 (which is preferable) with the structure surrounding the treatment area of the high frequency furnace 2. The belt support 32 also acts as a sliding surface for the metal strap 26. The metal upper portion 34 is electrically conductive, so that the layer of electrically insulating material 36 is found between the metal upper portion 34 and the metal belt 26 both electrically conductive. Preferably, the layer of electrically insulating material 36 completely covers an upper surface of the metallic upper portion 34, otherwise at least a portion of the upper surface capable of being in contact with the belt section 26 between the electrode structures 18, 20. The belt support 32 may comprise an arrangement 40 having a certain rigidity or conferring mechanical properties specific to the belt support 32, for example to provide support for the metal upper portion 34 when it is thin or in an insufficiently rigid material and provide additional mechanical strength if desired or necessary.
La partie supérieure métallique 34 est de préférence faite en métal paramagnétique ou diamagnétique, comme par exemple l'aluminium, un alliage d'aluminium, le cuivre, le laiton et les aciers inoxydables de série 300. La partie supérieure 34 peut prendre la forme d'une plaque comme montré à la Figure 3D. La partie supérieure 34 peut aussi prendre la forme de segments successifs espacés les uns des autres dans la direction de déplacement des produits 6, comme montré à la Figure 3E. Les segments ont de préférence des largeurs sensiblement plus grandes que des distances d'espacement entre les segments, afin que l'aire de contact entre le support de courroie 32 et la section de courroie 26 entre les structures d'électrodes 18, 20 soit la plus grande possible et les gradients de potentiels soient les plus faibles possibles pour limiter les risques de rayonnement vers l'extérieur de la zone de traitement du four haute fréquence 2, par exemple via les pièges d'ondes 10, 12. De préférence, la couche de matériau électriquement isolant 36 et la section de courroie 26 entre les structures d'électrodes 18, 20 ont des zones de contact dont une superficie totale favorise une circulation du courant haute fréquence, par exemple une superficie totale d'au moins 0, 1 m2 là où le courant haute fréquence circule, ou selon l'impédance effective maximale visée. La couche de matériau électriquement isolant 36 a de préférence un coefficient de friction favorisant un glissement de la courroie métallique flexible 26. La couche de matériau électriquement isolant 36 peut être faite en matériau comme par exemple le nitrure de bore et l'oxyde d'aluminium (aluminium anodisé dur). L'oxyde d'aluminium peut être imprégné de particules de Téflon afin de réduire la friction avec la courroie 26 et augmenter la résistance à l'usure de la couche de matériau électriquement isolant 36. La couche de matériau isolant 36 peut être appliquée sur la partie supérieure métallique 34 comme un enduit ou par un autre procédé de recouvrement de surface, ou encore découler, tout dépendant du matériau constituant la partie supérieure métallique 34, d'un procédé comme un dépôt chimique en phase vapeur (ou CVD pour "chemical vapor déposition") ou une anodisation dure ou autre traitement de surface semblable. The metallic upper part 34 is preferably made of paramagnetic or diamagnetic metal, such as for example aluminum, an aluminum alloy, copper, brass and stainless steels of series 300. The upper part 34 may take the form of a plate as shown in Figure 3D. The upper portion 34 may also take the form of successive segments spaced from each other in the direction of movement of the products 6, as shown in Figure 3E. The segments preferably have widths substantially greater than spacing distances between the segments, so that the contact area between the belt support 32 and the belt section 26 between the electrode structures 18, 20 is the possible gradients and potentials gradients are the lowest possible to limit the risks of radiation to the outside of the treatment area of the high frequency furnace 2, for example via the wave traps 10, 12. Preferably, the layer of electrically insulating material 36 and the belt section 26 between the electrode structures 18, 20 have contact areas whose total area promotes a high frequency current flow, for example a total area of at least 0.1 m 2 where the high frequency current flows, or according to the maximum effective impedance targeted. The layer of electrically insulating material 36 preferably has a coefficient of friction promoting a sliding of the flexible metal belt 26. The layer of electrically insulating material 36 may be made of a material such as, for example, boron nitride and aluminum oxide. (hard anodized aluminum). The aluminum oxide may be impregnated with Teflon particles to reduce friction with the belt 26 and increase the wear resistance of the layer of electrically insulating material 36. The layer of insulating material 36 may be applied to the metal upper part 34 as a coating or by another surface covering method, or also depending, depending on the material constituting the metal upper part 34, a process such as a chemical vapor deposition (or CVD for "chemical vapor deposition ") or hard anodizing or other similar surface treatment.
Comme illustré dans les Figures 3A, 3B et 3C, la partie supérieure métallique 34 et la couche de matériau électriquement isolant 36 peuvent comporter des perforations communes 42 réparties le long du support de courroie 32. De préférence, la courroie métallique flexible 26 et la partie supérieure métallique 34 sont faites en un matériau à faible perméabilité magnétique et à conductivité électrique élevée par rapport à la couche de matériau électriquement isolant 36. En référence aux Figures 4A et 4B, il est montré d'autres configurations possibles d'un système convoyeur 4 pour four haute fréquence selon l'invention, particulièrement approprié, par exemple, pour chauffer ou sécher un produit sous forme de film ou nappe. Plutôt qu'une configuration linéaire comme montré à la Figure 1 , le système convoyeur 4 peut avoir une configuration où la zone de traitement décrit une courbe. Dans cette configuration, la structure d'électrode 18 a une face concave à l'intérieur de laquelle un rouleau d'extrémité du système convoyeur 4, agissant comme support de courroie 32, s'engage. La Figure 4A montre une configuration où la partie supérieure métallique 34 recouverte de la couche de matériau électriquement isolant 36 est formée par la périphérie du rouleau d'extrémité et reliée au générateur haute fréquence 22 (montré à la Figure 1 ) alors que la structure d'électrodes 18 est reliée à la masse. La Figure 4B montre une configuration similaire mais où la structure d'électrodes 18 est reliée au générateur 22 tandis que la partie supérieure métallique 34 est reliée à la masse. As illustrated in FIGS. 3A, 3B and 3C, the metallic upper portion 34 and the layer of electrically insulating material 36 may have common perforations 42 distributed along the belt support 32. Preferably, the flexible metal belt 26 and the portion metallic upper 34 are made of a material with low magnetic permeability and high electrical conductivity with respect to the layer of electrically insulating material 36. With reference to Figures 4A and 4B, it is shown other possible configurations of a conveyor system 4 for high frequency furnace according to the invention, particularly suitable, for example, for heating or drying a product in the form of film or web. Rather than a linear configuration as shown in Figure 1, the conveyor system 4 may have a configuration where the treatment area describes a curve. In this configuration, the electrode structure 18 has a concave face within which an end roller of the conveyor system 4, acting as belt support 32, engages. Figure 4A shows a configuration where the upper part metal 34 covered with the layer of electrically insulating material 36 is formed by the periphery of the end roller and connected to the high frequency generator 22 (shown in Figure 1) while the electrode structure 18 is connected to ground. Figure 4B shows a similar configuration but where the electrode structure 18 is connected to the generator 22 while the metal top 34 is connected to ground.
En référence à nouveau à la Figure 1 , l'ensemble courroie 26 / support de courroie 32 est de préférence conçu de façon à obtenir une valeur d'impédance au passage de courants à la fréquence d'opération du générateur 22 la plus faible possible. À cette fin, la couche de matériau électriquement isolant 36 est la plus mince possible, ou encore la surface de contact entre la section de la courroie 26 au niveau de la partie supérieure métallique 34 est la plus grande possible. Referring back to FIG. 1, the belt / belt support assembly 32 is preferably designed to provide an impedance value for the flow of currents at the lowest possible generator operating frequency. For this purpose, the layer of electrically insulating material 36 is as thin as possible, or the contact area between the section of the belt 26 at the metal top 34 is as large as possible.
À titre d'exemples non limitatifs, une couche de matériau électriquement isolant 36 obtenue par anodisation dur de surface d'une plaque d'alliage d'aluminium formant la partie supérieure métallique 34 pourrait avoir une épaisseur comprise entre 5 et 150 microns. Une courroie 26 faite en acier inoxydable de la série 300 pourrait avoir une épaisseur de 0,2 mm à 3 mm. Pour une partie supérieure métallique 34 en aluminium et une couche de matériau électriquement isolant 36 obtenue par anodisation dure, l'épaisseur de la couche d'alumine résultant de l'anodisation peut être (ce n'est pas une science exacte) environ 2 fois plus épaisse que le métal "mangé" durant l'anodisation. Donc pour une couche isolante d'alumine ayant une épaisseur de 10 microns, une partie supérieure 34 en aluminium aura été réduit en épaisseur de 5 microns puisque l'alumine provient de l'aluminium soumis au procédé d'anodisation. Grosso modo, la densité volumique de l'aluminium est environs 2 fois plus grande que la couche d'alumine. L'aluminium devrait donc, au départ, avoir de préférence la même épaisseur que la couche d'alumine désirée (la moitié de l'aluminium disponible au départ est transformé en alumine). Parmi les trois types d'anodisation d'aluminium, type I, type I I et type II I, le type II I est préféré car plus résistant à l'abrasion que les autres. Il est à noter que pour d'autres types de matériaux, par exemple de l'argent recouvert de Téflon, d'autres considérations peuvent être impliquées. By way of nonlimiting examples, a layer of electrically insulating material 36 obtained by hard surface anodization of an aluminum alloy plate forming the upper metallic part 34 could have a thickness of between 5 and 150 microns. A belt 26 made of stainless steel 300 series could have a thickness of 0.2 mm to 3 mm. For a metallic upper portion 34 made of aluminum and a layer of electrically insulating material 36 obtained by hard anodizing, the thickness of the alumina layer resulting from the anodization may be (it is not an exact science) about 2 times thicker than metal "eaten" during anodization. Thus for an insulating layer of alumina having a thickness of 10 microns, an upper portion 34 of aluminum has been reduced to a thickness of 5 microns since the alumina comes from the aluminum subjected to the anodizing process. Roughly speaking, the volume density of aluminum is about 2 times greater than the alumina layer. The aluminum should therefore initially have preferably the same thickness as the desired alumina layer (half of the aluminum initially available is converted into alumina). Of the three types of aluminum anodization, type I, type II and type II I, type II is preferred because it is more resistant to abrasion than the others. It should be noted that for other types of materials, for example Teflon coated silver, other considerations may be involved.
Le système convoyeur 4 selon l'invention peut servir à diverses applications ayant une combinaison des caractéristiques qui suivent: faire appel au chauffage ou séchage par haute fréquence; convoyage de matériaux à travers un four haute fréquence; convoyage de matériaux non compatibles avec des polymères; électrodes d'application d'énergie ayant une grande surface (par exemple de forme capacitive); produits à chauffer nécessitant une température de plus de 100°C; grande densité de puissance; risque élevés pour des arcs électriques. Entre autres, le système convoyeur 4 est particulièrement utile au domaine du séchage du bois avec un équipement de séchage par haute fréquence comme celui montré dans la demande WO 2009/006737 (Kendall et al.). Le système convoyeur 4 peut aussi servir à des applications de chauffage, séchage ou décongélation de produits alimentaires par haute fréquence en continu. L'utilisation d'une courroie 26 lisse en acier inoxydable permet le développement d'applications nécessitant des équipements de grade alimentaire, par exemple certains produits pharmaceutiques. The conveyor system 4 according to the invention can be used for various applications having a combination of the following characteristics: using heating or drying by high frequency; conveying materials through a high frequency furnace; conveying materials not compatible with polymers; energy application electrodes having a large area (eg of capacitive shape); products to be heated requiring a temperature of more than 100 ° C; high power density; high risk for arcing. Among others, the conveyor system 4 is particularly useful in the field of wood drying with a high frequency drying equipment such as that shown in the application WO 2009/006737 (Kendall et al.). The conveyor system 4 can also be used for heating applications, drying or thawing food products by high frequency continuously. The use of a smooth stainless steel belt 26 allows the development of applications requiring food grade equipment, for example certain pharmaceutical products.
Bien que des réalisations de l'invention aient été illustrées dans les dessins ci- joints et décrites ci-dessus, il apparaîtra évident pour les personnes versées dans l'art que des modifications peuvent être apportées à ces réalisations sans s'écarter de l'invention. Although embodiments of the invention have been illustrated in the accompanying drawings and described above, it will be apparent to those skilled in the art that modifications can be made to these embodiments without departing from the art. invention.

Claims

REVENDICATIONS: CLAIMS:
1 . Système convoyeur pour déplacer des produits entre des structures d'électrodes supérieure et inférieure d'un four haute fréquence, le système convoyeur comprenant: 1. A conveyor system for moving products between upper and lower electrode structures of a high frequency furnace, the conveyor system comprising:
une courroie métallique flexible destinée à recevoir les produits à déplacer dans le four haute fréquence et formant une bande continue, la courroie métallique ayant une section s'étendant entre les structures d'électrodes du four haute fréquence; et  a flexible metal belt for receiving the products to be moved in the high frequency furnace and forming a continuous band, the metal belt having a section extending between the electrode structures of the high frequency furnace; and
un support de courroie ayant une partie supérieure métallique allongée dans une direction de déplacement des produits dans le four haute fréquence et faisant partie de la structure d'électrodes inférieure du four haute fréquence, et une couche de matériau électriquement isolant résistant à l'abrasion et à des arcs électriques, s'étendant sur la partie supérieure et sur laquelle la section de la courroie glisse, la section de la courroie, la partie supérieure métallique et la couche de matériau électriquement isolant formant un arrangement à effet capacitif propice à un transfert de courant haute-fréquence.  a belt support having an elongated metal upper portion in a direction of movement of the products in the high frequency furnace and forming part of the lower electrode structure of the high frequency furnace, and a layer of electrically insulating material resistant to abrasion and to the electrical arcs, extending over the upper part and on which the section of the belt slides, the section of the belt, the metallic upper part and the layer of electrically insulating material forming a capacitive effect arrangement conducive to a transfer of high-frequency current.
2. Le système convoyeur selon la revendication 1 , dans lequel la courroie est faite en métal paramagnétique ou diamagnétique. The conveyor system of claim 1, wherein the belt is made of paramagnetic or diamagnetic metal.
3. Le système convoyeur selon la revendication 1 , dans lequel le métal est un acier inoxydable austénitique de série 300. The conveyor system of claim 1, wherein the metal is a 300 series austenitic stainless steel.
4. Le système convoyeur selon la revendication 1 , dans lequel la courroie a une surface inférieure substantiellement lisse. The conveyor system of claim 1, wherein the belt has a substantially smooth bottom surface.
5. Le système convoyeur selon la revendication 4, dans lequel la courroie a une surface supérieure substantiellement lisse. The conveyor system of claim 4, wherein the belt has a substantially smooth upper surface.
6. Le système convoyeur selon la revendication 1 , dans lequel la courroie comporte des perforations réparties le long de la courroie. The conveyor system of claim 1, wherein the belt has perforations distributed along the belt.
7. Le système convoyeur selon la revendication 6, dans lequel les perforations forment un motif régulier le long de la courroie. The conveyor system of claim 6, wherein the perforations form a regular pattern along the belt.
8. Le système convoyeur selon la revendication 1 , dans lequel la partie supérieure métallique a une surface supérieure, et la couche de matériau électriquement isolant recouvre substantiellement la surface supérieure de la partie supérieure métallique. The conveyor system of claim 1, wherein the metal top portion has an upper surface, and the layer of electrically insulating material substantially covers the upper surface of the metal top portion.
9. Le système convoyeur selon la revendication 1 , dans lequel la couche de matériau électriquement isolant a un coefficient de friction favorisant un glissement de la courroie métallique flexible. 9. The conveyor system of claim 1, wherein the layer of electrically insulating material has a coefficient of friction promoting a sliding of the flexible metal belt.
10. Le système convoyeur selon la revendication 1 , dans lequel la couche de matériau électriquement isolant a une épaisseur substantiellement comprise entre 5 et 150 microns. The conveyor system of claim 1, wherein the layer of electrically insulating material has a thickness of substantially between 5 and 150 microns.
1 1 . Le système convoyeur selon la revendication 1 , dans lequel le matériau électriquement isolant est choisi du groupe comprenant le nitrure de bore et l'oxyde d'aluminium. 1 1. The conveyor system of claim 1, wherein the electrically insulating material is selected from the group consisting of boron nitride and aluminum oxide.
12. Le système convoyeur selon la revendication 1 1 , dans lequel l'oxyde d'aluminium est imprégné de particules de Téflon. 12. The conveyor system of claim 11, wherein the aluminum oxide is impregnated with Teflon particles.
13. Le système convoyeur selon la revendication 1 , dans lequel la partie supérieure métallique comprend une plaque d'aluminium. The conveyor system of claim 1, wherein the metal top comprises an aluminum plate.
14. Le système convoyeur selon la revendication 1 , dans lequel la partie supérieure métallique est faite en métal paramagnétique ou diamagnétique. 14. The conveyor system according to claim 1, wherein the metal upper part is made of paramagnetic or diamagnetic metal.
15. Le système convoyeur selon la revendication 1 , dans lequel la partie supérieure métallique et la couche de matériau électriquement isolant comportent des perforations communes réparties le long du support de courroie. The conveyor system of claim 1, wherein the metallic upper portion and the electrically insulating material layer have common perforations distributed along the belt support.
16. Le système convoyeur selon la revendication 1 , dans lequel la partie supérieure métallique comporte des segments successifs espacés les uns des autres dans la direction de déplacement des produits, les segments ayant des largeurs substantiellement plus grandes que des distances d'espacement entre les segments. The conveyor system of claim 1, wherein the metallic upper portion has successive segments spaced apart from each other in the direction of movement of the products, the segments having substantially larger widths than spacing distances between the segments. .
17. Le système convoyeur selon la revendication 1 , dans lequel la couche de matériau électriquement isolant et la section de courroie ont des zones de contact dont une superficie totale favorise une circulation du courant haute fréquence. The conveyor system of claim 1, wherein the layer of electrically insulating material and the belt section have contact areas whose total area promotes high frequency current flow.
18. Le système convoyeur selon la revendication 1 , dans lequel la partie supérieure métallique est faite en métal choisi du groupe comprenant l'aluminium, un alliage d'aluminium, le cuivre, le laiton et les aciers inoxydables de série 300. The conveyor system of claim 1, wherein the metal top is made of selected metal from the group consisting of aluminum, aluminum alloy, copper, brass, and 300 series stainless steels.
19. Le système convoyeur selon la revendication 1 , dans lequel la couche de matériau électriquement isolant est obtenue par anodisation dure d'une surface supérieure de la partie supérieure métallique. 19. The conveyor system of claim 1, wherein the layer of electrically insulating material is obtained by hard anodizing an upper surface of the metal top.
20. Le système convoyeur selon la revendication 1 , dans lequel le support de courroie a un arrangement substantiellement rigide portant la partie supérieure métallique. The conveyor system of claim 1, wherein the belt support has a substantially rigid arrangement carrying the metal top.
21 . Le système convoyeur selon la revendication 1 , dans lequel au moins un de la courroie métallique flexible et de la partie supérieure métallique est faite en un matériau à faible perméabilité magnétique et à conductivité électrique élevée par rapport à la couche de matériau électriquement isolant. 21. The conveyor system of claim 1, wherein at least one of the flexible metal belt and the metallic upper portion is made of a material of low magnetic permeability and high electrical conductivity with respect to the layer of electrically insulating material.
PCT/CA2013/050317 2012-04-26 2013-04-25 Conveyor system for a high-frequency furnace WO2013159230A1 (en)

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