Patent Application
20200348079
The invention relates to a heat treatment installation for the production of industrial products, notably in the field of composite materials and/or of 3D printing.
In this field, the operations required for the production of the industrial products include heat treatments and/or treatments under a controlled atmosphere. These particular treatments are carried out in dedicated chambers in which the temperature, pressure and/or atmospheric conditions can be controlled and sustained over what can sometimes be lengthy periods. These chambers are, for example, relaxation chambers, binder-removal ovens for the removal of a manufacturing binder via evaporation or carbonization, firing kilns, drying or dewatering ovens. It is often the case in manufacturing processes that industrial products are treated successively in several chambers that have different functions, for example a drying chamber and a firing chamber, or a binder-removal chamber and a high-temperature sintering chamber. Because the chambers are each devoted to a particular treatment, the industrial products in the process of being manufactured are handled in such a way as to correspond to the location and particular layout of each chamber. They need to be distributed according to the availability of the chambers, their dimensional characteristics and the nature of the supports that they accept or dictate. Furthermore, because the chambers are specific, their treatment times are generally fixed.
Document FR 1 247 845 describes a device for firing ceramic products comprising three fixed chambers with different thermal characteristics, it being possible for the treatment temperature to reach 1400° C. The products that are to be treated are placed on a trolley that can be moved between the chambers.
Document DE 1221253 describes an electric heating oven with two opposite entrances which are used alternately for the cooling of the treated products and for supplying with products that are to be treated. There is just one chamber that is active and the products that are to be treated are moved horizontally using trolleys.
In the case of innovative industrial products employing heat treatments, the treatment times need to be adapted to suit. One disadvantage stems from the need to transfer products from one treatment chamber to another with the spatial layout of the products being adapted to suit the volume available in each chamber. The handling operations associated with these transfers are the source of numerous difficulties. They may give rise to defects in the components. They disrupt the rapid sequencing of the treatment operations and automation thereof. They represent a significant investment cost and often require the presence of operators to monitor them. They lead to variations in the temperature of the products, generally to cooling, between the various treatment phases, and this represents at once a risk to the quality of the products, a not-insignificant waste of energy, and a loss in terms of the productivity of the installation.
One of the objects of the invention is to propose a heat treatment installation for the production of industrial products that avoids the aforementioned disadvantages.
Another object of the invention is to propose a heat treatment installation for the production of industrial products in which the handlings of the products are reduced to the operations of placement prior to treatment and of removal post-treatment, without any intervention, between the heat treatment operations, regarding the spatial organization of the products corresponding to the stacking and the distribution of the products in the working treatment volume.
The subject of the invention is a heat treatment installation for the production of industrial products, comprising several chambers with different thermal characteristics, and a support comprising a base to accept the products that are to be treated, characterized in that: the support is stationary, the chambers are distributed about an axis, and mechanical means provide the relative movement of the base and of the chambers and the coupling between a chamber and the base.
According to one embodiment of the invention, the mechanical means comprise a motorized pivot for causing the set of chambers to pivot about the axis, and a hydraulic cylinder for causing the relative movement of the base and of the set of chambers.
According to one embodiment of the invention, the axis of pivoting of the chambers is a horizontal axis.
According to one embodiment of the invention, the relative movement of the base and of the chambers is a vertical movement.
According to one embodiment of the invention, the vertical movement is a movement of the chambers with respect to the base.
According to one embodiment of the invention, the vertical movement is a movement of the base with respect to the chambers.
According to one embodiment of the invention, the set of chambers comprises two chambers.
According to one embodiment of the invention, the set of chambers comprises three chambers.
According to a first embodiment of the invention, the heat treatment installation for the production of industrial products is essentially made up of a fixed support 1 for receiving the industrial products that are to be treated, and of a fixed gantry 2 bearing several heat treatment chambers.
In the embodiment of
In
The stabilization and binder-removal chamber 3 operates at a temperature of several hundred degrees C. It is made up of a sealed bell housing 11 surrounded with resistive heating elements 12 and lined with low-temperature insulators 13 such as mineral wools.
The high-temperature sintering chamber 4 operates at a temperature that can be as high as around 1600° C. It is made of refractory bricks 14 and ceramic or mineral wool and its active cavity 16 is surrounded with resistive heating elements 15. The active cavity 16 is bordered by a parapet 17.
The fixed support 1 comprises a base 18 bearing a refractory protection 19 with a rim 20, surmounted by a plate 21 able to accept the industrial products 22 that are to be treated. Underneath the plate 21 there opens a duct 23 passing through the base 18 and connecting the treatment chamber 3 or 4 to an atmosphere-control system 24. The atmosphere-control system 24 is able, by means of a fan 25, to extract the gases resulting from the heat treatment of the products 22, to treat them in the zone 26 for the post-combustion of the OCs, and to discharge them via the flue 27. The atmosphere-control system 24 is also able to supply the chamber 3 or 4 with a specific gas such as nitrogen at certain stages in the treatment, from a pressurized gas reserve.
In the first embodiment of
In a second embodiment schematically illustrated in
In a third embodiment also corresponding to the outline of
In this third embodiment, only the base 18 is subjected to the vertical movements. This results in a certain energy saving because the base is markedly less heavy than the bearing structure 5 equipped with three chambers 28,29,30. According to an embodiment variant, the pivot of the bearing structure that bears the chambers has a vertical axis and the chambers are juxtaposed on the bearing structure, each with their opening facing downward. The rotation of the pivot on its vertical axis brings about the switching-over of the chambers. The number of chambers can thus be increased to four. The vertical movement for placing the base in a chamber can be provided either by lowerings of the chamber or by the raising of the base.
The invention is characterized by the use, for successive heat treatments, of dedicated chambers positioned in succession over the products that are to be treated, without any intervention on the spatial organization of the products, such as the stacking or the distribution of the products in the working treatment volume. The base accepts the products and is coupled in succession to each of the treatment chambers, without the products being handled and/or without human intervention for control. This process is particularly well suited to production methods in which it is essential for each manufacturing step to be connected to the subsequent treatments. By way of example, in the case of 3D printing, the manufacturing time may last several tens of hours. The manufacturing batch corresponds to the working volume of the printer. After manufacture, the products are very fragile and need to be stabilized. The stabilization or relaxation treatment may last for 48 hours in an atmosphere in which the temperature and relative humidity are controlled. Next, the binder-removal operation consists in causing the binders contained in the products to be removed, by gasification-combustion, it being possible for the gasification to be performed under vacuum or in a neutral atmosphere. This operation may last from 2 to 3 days depending on the complexity of the products. The oxygen content and the temperature are controlled in order to avoid excessively rapid combustion which might destroy the products. The heating needs to be electrical or indirect in order to avoid contact between the gases and heating elements. The binder-removal operation is performed under a sealed bell housing to avoid the dispersion of pollutant gases. According to one exemplary embodiment, a post combustion in the zone 26 is scheduled to burn off the VOCs resulting from the binder removal. The contaminated gases are extracted through the base via the duct 23.
In the exemplary embodiment described, the second operation described uses a sealed chamber for binder removal. This sealed chamber can be used for any type of heat treatment, under vacuum or under a specific gaseous atmosphere.
The third operation consists of a firing or sintering operation at a high temperature, up to 1650° C. for around 24 hours. This operation needs to be performed in a specific chamber because the bell housing of the binder-removal chamber would not withstand the sintering temperature.
The advantages of the heat treatment installation according to the invention are numerous. Having a single base and several chambers makes it possible to group together on the base a significant proportion of the hardware and of the control functions and, in particular: the gas inlets and outlets for the atmosphere control and for extracting the reaction gases; the gas analyzers and sensors, some of which are multifunctional; the power regulation and control system; the thermal insulation, and the mechanics used for the relative positionings of the base and the various chambers. The fact that the heat treatment operations are strung together without moving around the products that are to be treated ensures a rapid change in treatment conditions, reduces the risk of product degradation, and affords an energy saving.
Finally, the automation of the movements of the chambers according to the various steps of the heat treatment process dispenses with the presence of personnel throughout the duration of the process which may extend over several days.
| Number | Date | Country | Kind |
|---|---|---|---|
| 17 60986 | Nov 2017 | FR | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/FR2018/052741 | 11/6/2018 | WO | 00 |
