The present invention relates to a method and the devices intended to allow the movement of loads inside furnaces, in particular high temperature furnaces intended for the baking of ceramics.
The expression “high temperatures” is used here to denote processing temperatures in the range between 700 and 1800 degrees Celsius.
In general terms, a furnace is constituted by a chamber inside which the conditions of temperature, pressure and atmosphere necessary for the transformation of the products to be baked are achieved.
The expression “baking tunnel” is used here to denote the zone delimited by the four adjacent walls, being: the two lateral walls also referred to as “right feet”, the upper surface referred to as the “roof” and the lower surface referred to as the “bed”.
The scope of the invention is limited to the furnaces in which the products to be baked are introduced into the baking chamber via one of the extremities of the baking tunnel and emerge after heat treatment either via the same extremity, or via the opposite extremity.
Doors or some other means permitting the exchanges between the baking chamber and the atelier to be controlled are sometimes available at the extremities of said tunnel.
The most familiar and also the oldest method of moving the products to be baked inside a furnace has been to position them on mobile structures that are generally referred to as “furnace cars”, the products to be baked being placed on the upper surface of said cars.
The upper zone of each of the furnace cars is constituted by a slab of refractory materials and thermal insulation materials intended, on the one hand, to support the load of the products to be baked and, on the other hand, to limit the thermal exchanges with the outside of the furnace.
Said slab of refractory and insulating materials is supported by a metal chassis, which is itself equipped with wheels or some other mechanical means permitting the furnace car to be moved easily.
The slab of refractory and insulating materials forms a thermal shield between the high temperature baking zone and the mechanical means of transport situated beneath the metal chassis.
In the furnace, the furnace cars are arranged in contact with each other and thereby constitute the bed of the baking tunnel.
In order to insulate the baking tunnel, situated above the bed, from the service passage, situated below the bed, it is well known to provide, on the one hand, sealing aprons carried by the furnace cars at the same height as the bed and, on the other hand, sand trays that are integral with the lateral walls of the furnace. Interacting means of this kind are described in documents DE 23 54 463 and DE 20 16 537.
The metal chassis and said mechanical means of movement must be maintained at an acceptable temperature for the materials and the lubrication products that are used. For this purpose, forced ventilation or natural convection of the zone beneath the cars is generally provided within the design of the furnace.
This solution is used universally today, in spite of the fact that it has numerous disadvantages:
Certain manufacturers have imagined replacing the furnace cars occupying the entire width of the baking tunnel with narrow cars, thus forming a plurality of parallel mobile structures in the bed of the baking tunnel, yet without solving either the problems of sealing or the overheating of the mechanical means of movement situated under the narrow cars.
Another known solution to the problem of the movement of the products inside the furnaces is the roller furnace.
In a roller furnace, the baking tunnel is delimited by fixed walls constituting the bed of the furnace, the roof and the lateral walls.
In a roller furnace, the products to be baked are placed on rollers passing through the lateral walls of the baking tunnel. Said rollers are supported and driven in rotation by a mechanism situated on the outside of the baking tunnel on the lateral walls.
This solution, which is very widespread in the tile-making industry, is limited by the length of the rollers and the load capable of being supported by said rollers.
A further disadvantage of the roller furnace is the lack of sealing due to the numerous passages of the rollers over the lateral walls of the baking tunnel.
The purpose of the invention is to propose a solution for the movement of the products inside a baking tunnel, of which all the walls are fixed, and without any mechanical element intended for the movement of the products passing through any of the four fixed and adjacent walls which delimit said tunnel.
The invention has as its object a high temperature baking furnace, comprising:
characterized in that it comprises rolling means between the fixed structures and the mobile elements to allow the movement of the mobile elements along the fixed structures; in that the movement of the loads inside the furnace is assured in the absence of interaction between the walls of the baking tunnel and the means of moving the loads in the furnace, and in that, inside the baking tunnel, said fixed structures, said mobile elements and said rolling means are subjected to the same conditions of temperature and atmosphere as the zone of the baking tunnel where they are situated.
Advantageously, the fixed structures pass through the baking tunnel from one end to the other and comprise sections arranged end-to-end, each section being maintained in position by one or a plurality of support members resting on one or a plurality of the fixed walls of the baking tunnel.
In an advantageous manner, the mobile elements are juxtaposed with mutual support and their movement is assured by action on certain of the elements situated close to the extremities of the baking tunnel.
Preferably, the rolling means, known as skids, are constituted by an assembly of from two to six wheels having at least one cylindrical zone, connected together at their axis by one or a plurality of spacers intended to limit the relative movement of the wheels and thereby to prevent two adjacent wheels of the same skid or of two successive skids from coming into contact.
Advantageously, the profile of the wheels is adapted to the profiles of the sections of the fixed structures and of the mobile elements so as to allow the longitudinal guiding of the mobile elements as they move.
In an advantageous manner, the profile of the mobile elements is adapted to the profile of the sections of the fixed structures so as to allow the longitudinal guiding of the mobile elements on the fixed structures.
Preferably, the cylindrical zones of the wheels receiving the load of mobile elements possess a diameter different to those transmitting this load to the sections of the fixed structures.
Advantageously, the skids move at a speed lower than that of the mobile elements.
The invention also has as its object a method of routing the loads to be baked in a high temperature baking furnace, characterized by the steps of:
Advantageously, the mobile elements and the skids are picked up at the exit from the tunnel by a handling device which transfers them outside the baking tunnel as far as the entrance in order to be reused.
The invention is described with reference to the accompanying drawings, in which:
With reference to these drawings, it is possible in the different views to distinguish the lateral walls 1, the roof 2 and the bed 3 of the baking tunnel and the loads of products to be baked 4.
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It is also possible to distinguish the baking supports that are configured as bars 18 and the loads of products to be baked 4.
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The devices for the movement of the products in a high temperature baking tunnel according to the invention are constituted on the one hand:
Said mobile elements 13 are juxtaposed with mutual support, and their movement is assured by action on certain of the elements 13 situated close to the extremities of the baking tunnel.
The installation according to the invention comprises devices 14 arranged between the fixed structures 10 and the mobile elements 13 and facilitating the movement of said elements, which are designated by the expression “skids”.
Baking supports constituted by bars 18 or by frames receive the products to be baked and connect the upper surfaces of the mobile elements 13 transversely to their axes of movement in the baking tunnel.
The invention is further characterized in that:
According to one embodiment, the profile of all or certain wheels 15 is adapted to the profiles of the sections 11 of the fixed structure 10 and of the mobile elements 13 so as to allow the longitudinal guiding of the mobile elements as they move.
According to one embodiment, the cylindrical zones of the wheels 15 receiving the load of mobile elements 13 possess a different diameter to those transmitting this load to the sections 11 of the fixed structure.
According to another embodiment, the longitudinal guiding of the mobile elements 13 on the sections 11 of the fixed structure is assured by the spacers 16 of the skids 14.
According to another embodiment, the profile of the mobile elements 13 is adapted to the profile of the fixed structures 10 so as to allow the longitudinal guiding of the mobile elements 13 on the sections 11 of the fixed structure.
The method of routing the loads to be baked in a furnace according to the invention comprises the steps of:
a) on a longitudinal fixed support and guide structure 10, positioning at intervals skids 14 capable of allowing movement,
b) on the skids 14, positioning mobile elements 13 juxtaposed in the longitudinal direction of movement,
c) on the mobile elements 13, placing the baking supports 18 and the loads 4 to be baked,
d) at one extremity of the tunnel, applying a push to the mobile elements 13 to cause them to advance.
Preferably, the mobile elements 13 and the skids 14 are picked up at the exit from the tunnel by a handling device which transfers them outside the baking tunnel as far as the entrance in order to be reused.
The industrial applications for the invention relate primarily to the tunnel furnaces and batch furnaces of the ceramic and metallurgical industries and more generally to high temperature heat treatment furnaces, controlled atmosphere furnaces or rapid cycle furnaces.
The mode of movement proposed by the invention makes it possible to avoid any thermal losses due to the presence of the mobile load supports such as the furnace cars and to ensure perfect sealing of the baking chamber.
The utilization of the invention permits a reduction in the baking cycles and in the thermal consumption in these industries and the improvement of the quality of the products through the homogeneity of the baking conditions in the section of the baking tunnel.
Number | Date | Country | Kind |
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12 58857 | Sep 2012 | FR | national |
Filing Document | Filing Date | Country | Kind |
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PCT/FR2013/052018 | 9/3/2013 | WO | 00 |