EP0823608B1 - Process and installation to convey loads in a vacuum furnace and vacuum furnace with such an installation - Google Patents

Abstract

The conveyor system for a vacuum kiln (1) with an air lock (4,5) at its inlet and/or outlet ends and doors (6,7) leading into and out of its main inner chamber (2). It has the loads (3c,3d) situated immediately before the chamber's outlet and inlet doors situated at a lower level than the other loads (3a,3b) inside the chamber. This is to enable the loads to be moved in sequence by a beam (10) which moves vertically and horizontally beneath them. The beam lifts the load (3c) immediately adjacent to the outlet door and moves it through the door without affect the positions of the other loads in the chamber. Returning to the forward end of the chamber, the beam lifts the load (3d) adjacent to the inlet door and then the other loads inside the chamber, moving all three forwards into the chamber.

Description

The invention relates to a method and a device for conveying charges inside a vacuum oven and to an improved vacuum oven equipped with such a device.

A vacuum oven is generally equipped with an entry and exit airlock, respectively separated from an interior vacuum chamber in which the heat treatment of the charges is carried out. Several charges are generally introduced into the oven and progressively pass from a position close to the entry airlock to a position close to the exit airlock, each position possibly corresponding to different processing conditions, such as temperature or ambient gas. . It is therefore necessary to convey the loads both in the interior chamber of the oven and between the airlocks and the interior chamber.

It is possible to use a system of carriages arranged on treads on which they move by means of rollers. However, these rollers tend to wear or seize, which can lead to blockage of the conveying device.

In conventional ovens, that is to say comprising no vacuum chamber, one can use a beam lifting the loads and moving them along a substantially horizontal path inside the oven. Such a device is known under the name "no pilgrim". However, in a device with a vacuum chamber, a pilgrim step known from the prior art cannot be used because the distance between the charges inside the vacuum chamber must be as small as possible, this is that is to say for example of the order of 100 mm, in order to optimize the occupation of the vacuum chamber, while the distance between a charge located in one of the entry or exit airlocks and the charge nearest located in the vacuum chamber must allow the passage and / or movement of a door separating the airlock and the vacuum chamber. Thus, the distance between a load located in the airlock and a load located in the vacuum chamber is often close to 1 meter. If a classic pilgrim's step is used to move both a load located in one of the airlocks and at least one load located in the vacuum chamber, that is one of the loads at least reaches a position in which it is not possible to close one of the doors separating the airlocks from the vacuum chamber, or the charges are placed inside the chamber with a distance of the order of a meter , which makes an equivalent length of the vacuum chamber unusable and reduces the economic performance of the device.

It is possible to use a conveying device, such as a pilgrim's step as in DE-C-963.609 or DE-A-4.140.740, for the loads located inside the vacuum chamber and the tables transfer to pass the loads from an airlock to the room or vice versa as in US-A-4 741 695. However, the cost and complexity of the two necessary transfer tables are significant drawbacks.

The invention aims to solve these problems and to allow the use of a device with beam for displacement of the charges, that is to say with no pilgrim, allowing a selective displacement of the charges and an optimal use of the chamber vacuum without interference with the separation doors of the vacuum chamber and airlocks.

In this spirit, the invention relates to a method of conveying charges inside a vacuum oven, equipped with an entry airlock and / or an exit airlock respectively separated from an interior chamber under vacuum of said oven by a door, characterized in that it consists in supporting loads located immediately upstream of said doors at a height lower than the height at which the other loads are supported inside said interior chamber and in moving the '' at least one of said loads located immediately upstream of said doors along a substantially horizontal trajectory situated at an altitude lower than the support height of said other loads inside said chamber and at the altitude of the path of movement of said other loads .

The fact of supporting the loads located immediately upstream of the doors at a height lower than that at which the other loads are supported makes it possible to lift and move these loads located upstream of the doors independently of the other loads. The method of the invention therefore makes it possible to pass the doors of the airlocks entering and leaving the oven to the loads located immediately upstream selectively, that is to say without displacing the other loads contained in the oven. The method of the invention also makes it possible to adapt the spacing of the loads inside the oven by moving the loads located immediately upstream of the doors.

According to a first advantageous aspect of the invention, the method also consists in moving the load closest to the exit lock, alone, from the interior chamber to the exit lock. Thus, the load close to the load closest to the exit airlock is not likely to be brought, at the same time as the load closest to the exit airlock, to a position in which it would oppose the operation of the door separating the vacuum chamber from the exit airlock.

According to another advantageous aspect of the invention, the method consists in moving, at a first altitude, a load located in the entry airlock to a position in which its distance to the nearest load located in the interior chamber is substantially equal to the distance between two charges located in the interior chamber and then to move jointly, at a second altitude greater than the first altitude, said charge and the charges situated in said internal chamber to a position where all the charges are located in said interior chamber. Thus, the method of the invention makes it possible to arrange the load entering the interior chamber at a distance from the nearest load such that they can then be moved together in the direction of the exit airlock and positioned in the interior chamber with optimal spacing.

The invention also relates to a device making it possible to implement the method of the invention and, more specifically, a device for conveying charges inside a vacuum oven equipped with an inlet airlock and / or an outlet airlock respectively separated from an interior vacuum chamber of said oven by a door, characterized in that it comprises a beam capable of moving said loads by a vertical and horizontal movement between said airlocks and said interior chamber and in said interior chamber and in that it comprises means for supporting said loads in said interior chamber and / or in said airlock immediately upstream of said doors and means for supporting said loads downstream of said doors, said upstream support means being able to support said loads at heights lower than that of said downstream support means, said beam being able to move selectively, along substantially horizontal trajectories located at altitudes below the height of said downstream support means, said loads supported by said upstream support means for the passage of said doors.

Thanks to the device of the invention, the loads are stored in the oven at different heights, so that the beam of the pilgrim's step can come into contact with the loads located upstream of the airlock doors and move them without interference with the other loads, which makes it possible to adjust the spacing of the loads according to their desired position.

According to an advantageous aspect of the invention, the beam is able to be moved along substantially horizontal trajectories located at different altitudes. Thanks to this aspect of the invention, the loads, which are located at different altitudes, are or are not placed on the trajectory of the beam of the device.

According to another advantageous aspect of the invention, the support means are arranged so that the load closest to the exit airlock located in the interior chamber is placed at an altitude lower than that of the other loads located in the interior chamber . This makes it possible to move this load alone, from the interior chamber to the exit airlock, without disturbing the positioning of the other loads in the interior chamber.

According to a first embodiment of the invention, the beam is provided with a plurality of rollers able to partially penetrate U-shaped rails movable at altitude and extending over substantially the entire length of the oven. This simple construction has proven to be particularly resistant and is practical to implement.

According to a second embodiment of the invention, the beam has an I-profile and is supported by rollers movable at altitude and fixed in translation partially penetrating between the wings of the I-profile. This construction is also simple and effective.

The invention finally relates to a vacuum oven comprising a conveying device as previously described or operating in accordance with the invention.

• la figure 1 est une vue en coupe longitudinale d'un four sous vide incorporant un dispositif de convoyage conforme à l'invention, dans une première position de convoyage ;
• les figures 2 à 6 sont des représentations schématiques des charges et de la poutre de convoyage du dispositif de la figure 1 à différentes étapes du procédé de convoyage de l'invention
• la figure 7 est une vue partielle, en coupe verticale, selon la ligne VII-VII à la figure 2 et
• la figure 8 est une vue analogue à la figure 7 pour un second mode de réalisation d'un dispositif de convoyage conforme à l'invention.

The invention will be better understood and other advantages thereof will appear more clearly in the light of the following description of two embodiments of a charge conveying device inside a vacuum oven in accordance with its principle, given solely by way of example and made with reference to the appended drawings in which:

• Figure 1 is a longitudinal sectional view of a vacuum oven incorporating a conveying device according to the invention, in a first conveying position;
• Figures 2 to 6 are schematic representations of the loads and the conveying beam of the device of Figure 1 at different stages of the conveying method of the invention
• FIG. 7 is a partial view, in vertical section, along the line VII-VII in FIG. 2 and
• Figure 8 is a view similar to Figure 7 for a second embodiment of a conveying device according to the invention.

In FIG. 1, a vacuum oven 1 essentially comprises an interior vacuum chamber 2, in which is carried out, by means of heating elements 2 a , the heat treatment of charges 3. An airlock 4 and an airlock outlet 5 are respectively separated from the interior chamber 2 by doors 6 and 7 capable of isolating the chamber 2 from the exterior. The doors 6 and 7 are shown sliding, but it is also possible to provide that these doors are pivoting. Reference 3 a , 3 b and 3 c the charges located in the chamber 2 and 3 d the charge located in the airlock 4 in Figure 1.

In the position of figure 1, we note that the distance d between the load 3 a and the load 3 b is much smaller than the distance D between the load 3 a and the load 3 d because the door 6 must be able to be inserted between charges 3 a and 3 d . Similarly, the distance d is much less than the distance D 'existing between the load 3 c and the limit of the position 3 e of a charge in the exit airlock 5 shown in phantom.

According to the invention, a beam 10 is provided under loads 3 a to 3 c . It is capable of moving in the plane of Figure 1 in a vertical direction and in a horizontal direction. The beam drive system is designed so that, when the doors 6 and 7 are open, the beam 10 can penetrate as close as possible to the exterior doors 11 and 12 of the airlocks 4 and 5.

Support legs 13 of the loads in their different positions 3 a to 3 e are provided and bear the references 13 a to 13 e respectively . According to the invention, these feet are provided to support loads 3 a to 3 d at different heights. Thus, the load 3 c is supported at an altitude a ₁ less than the altitude a ₃ of the loads 3 a and 3 b because the support feet 13 c have a height less than that of the support feet 13 a and 13 b . Furthermore, the beam 10 is displaced in height by a suitable system such as, for example, jacks 14 distributed over the length of the furnace 1.

As it appears by comparing Figures 1 and 2, when the beam 10 is lifted by the jacks 14 then moved towards the airlock 5, it is possible to lift the load 3 c relative to the feet 13 c and to move it to the airlock 5, and without the beam 10 comes into contact with the loads 3a and 3b which are supported by at altitudes above the legs 13 and 13b. This makes it possible to reach the position of FIG. 3 in which the load 3c rests on the feet 13 e and does not interfere with the closing of the door 7. The feet 13 e support the load 3 c at an altitude a ₄ , less than altitude a ₃ , which may or may not be equal to altitude a ₁ . The movement of the beam 10, which has been shown in FIGS. 2 and 3, is carried out while the upper edge of the beam is maintained at a first substantially constant height H ₁ . In other words, the beam has a substantially horizontal trajectory at a given first altitude.

In the position of figure 3, the location which was occupied by the load 3 c in the configuration of figure 1 is free and it is then possible to advance the other loads in the manner which is described with reference to FIGS. 4 to 6.

The door 7 being closed, the door 6 is open and the beam 10 is moved in the direction of the airlock 4 at a height less than the height H ₁ until it is positioned under the load 3 d as shown in Figure 4. In this position, the beam 10 is raised by the jacks 14 until it raises the load 3 d relative to its support legs 13 d . As the support legs 13 d have a height a ₂ less than the height or altitude a ₃ of the support legs 13 a and 13 b , lifting the load 3 d does not influence the positioning of the loads 3 a and 3 b as long as the load 3 d is not raised from a height greater than the difference in height between the feet 13 a and 13 d . The load 3 from being disengaged relative to its support legs 13 of the beam 10 is moved towards the outlet lock 5 so as to bring the load 3 d in a position such that the distance d 'between the loads 3a and 3 d is substantially equal to the distance d between the loads 3 a and 3 b , this position being represented in FIG. 5. We denote H ₂ the height of the upper edge of the beam 10 during the movement of the load transfer 3 d towards the interior of the chamber 2. It is possible to provide that the height H ₂ is substantially equal to or different from the height H ₁ .

The loads being in the position of FIG. 5, their spacing is such that they occupy a total volume allowing them to be placed in a group in the chamber 2. To do this, the beam 10 is raised to a height H ₃ greater than the height H ₂ , so that it can release the loads 3 a and 3 b relative to their respective support legs 13 a and 13 b while the load 3 d remains in abutment on the beam 10, then the beam 10 is moved towards the exit airlock 5 to reach the position shown in FIG. 6. In this position, the load 3 d is facing the support legs 13 a , the load 3 a is facing the support legs 13 b and the load 3 b is opposite the support feet 13 c . When the beam makes a downward movement, the loads 3 d and 3 a are firstly deposited on the support legs 13 a and 13 d then the load 3 b is deposited on the support legs 13 c , so that when the beam 10 reaches the low point of its trajectory the load 3 b is at a altitude lower than that of loads 3 a and 3 d . The charges located inside chamber 2 are then in the position of FIG. 1, with their numbering ready.

Thus, the loads 3 a to 3 d have been selectively displaced along substantially horizontal trajectories situated at different altitudes, namely with heights H ₁ , H ₂ and H ₃ different from the upper edge of the beam 10.

Note that the support legs 13a to 13e are fixed, so that they are particularly simple to produce. Their relative positions and the height adjustment of the beam 10 allow them, alone, to select the loads to be moved, in particular for the passage of the beams.

In FIG. 7, the means for positioning the height of the beam 10 appear more clearly. A jack 14 supports a plate 15 on which two rails 16 are arranged extending over substantially the entire length of the furnace 1. These rails 16 have a profile in coated U whose opening is oriented towards the beam 10. Furthermore, the beam 10 carries rollers 17 free in rotation about axes 18 fixed relative to the beam 10. Thus, the beam 10 can be moved horizontally by rolling of the rollers 17 inside the rails 16 while its altitude is adjusted by means of the jacks 14 distributed over its length, several altitudes being attainable as a function of the selected position of the jacks 14.

The conveying device shown in FIG. 8 is a second embodiment of a conveying device according to the invention, in which the elements similar to those of the embodiment of FIGS. 1 to 7 bear identical references increased by 50 This embodiment, which is shown while a load 53 c rests on its support legs 63 c , differs from the previous one, essentially in that the beam 60 has an I-profile and is supported by friction rollers 67 distributed over the length of the oven 1, these rollers having one end 67 a penetrating between the wings of the I-profile of the beam 60. The rollers 67 are fixed to a base 65 whose altitude can be adjusted by means of a jack 64. The rollers 67 are movable in altitude and fixed in translation relative to the body of the furnace 1 Thus, the rollers 67 are capable of guiding the beam 60 over its entire trajectory, including in the airlocks 4 and 5.

The invention has been shown with hydraulic or pneumatic cylinders 14 for adjusting the height of the beam 10 or 60, but any other suitable means can also be used to fulfill this function and, in particular, one or more electric motors or a wheel and worm system.

The furnace according to the invention therefore allows automated processing of the charges to be heated without the use of complex and expensive transfer tables or roller conveyors between the entry and / or exit airlocks and the interior vacuum chamber of the oven.

Claims (10)

1. Method of conveying loads (3) inside a vacuum furnace (1) equipped with an entry airlock (4) and/or an exit airlock (5) respectively separated from an interior vacuum chamber (2) of said furnace by a door (6, 7), characterised in that it consists in supporting loads (3c, 3d) located immediately upstream of said doors at a height (a₁, a₂) lower than the height (a₃) at which the other loads (3a, 3b) are supported inside said interior chamber, and in displacing at least one of said loads (3c, 3d) located immediately upstream of said doors along a substantially horizontal path located at a height (H₁, H₂) lower than the height (a₃) of the support (13a, 13b) for said other loads (3a, 3b) inside said chamber (2) and lower than the height (H₃) of the displacement path of said other loads (3a, 3b).
2. Conveying method according to claim 1, characterised in that it consists in displacing, on its own, the load (3c) closest to the exit airlock (5) from said interior chamber (2) towards said exit airlock.
3. Conveying method according to claim 1, characterised in that it consists in displacing, at a first height (H₂), a load (3d) located in said entry airlock (4) as far as a position (figure 5) in which its distance (d') from the closest load (3a) located in said interior chamber (2) is substantially equal to the distance (d) between two loads (3a, 3b) located in said interior chamber, then in displacing jointly, at a second height (H₃) higher than said first height, the said load and the loads located in said interior chamber as far as a position (figure 6) in which all the loads are located in said interior chamber.
4. Installation for conveying loads (3) inside a vacuum furnace (1) equipped with an entry airlock (4) and/or an exit airlock (5), respectively separated from an interior vacuum chamber (2) of said furnace by a door (6, 7), characterised in that it comprises a beam (10) capable of displacing said loads by means of a vertical and horizontal movement between said airlocks and said interior chamber and in said interior chamber and in that it comprises means (13c, 13d) of supporting said loads (3c, 3d) in said interior chamber and/or in said entry airlock immediately upstream of said doors, and means (13a, 13b) of supporting said loads (3a, 3b) downstream of said doors, said upstream supporting means (13c, 13d) being capable of supporting said loads at heights (a₁, a₂) lower than that (a₃) of said downstream supporting means (13a, 13b), said beam being capable of displacing selectively, along substantially horizontal paths located at heights (H₁, H₂) lower than the height (a₃) of said downstream supporting means (13a, 13b), the said loads ( 3c, 3d) supported by said upstream supporting means to pass through said doors.
5. Conveying installation according to claim 4, characterised in that the said beam (10) is capable of being displaced along substantially horizontal paths located at different heights (H₁, H₂, H₃).
6. Conveying installation according to claim 4, characterised in that the said supporting means (13a, 13b, 13c) are arranged in such a way that the load (3c) closest to said exit airlock (5) located in said interior chamber (2) is placed at a lower height than that of the other loads (3a, 3b) located in said interior chamber.
7. Conveying installation according to claim 6, characterised in that the said supporting means (13) are arranged in such a way that the said other loads (3a, 3b) located in said interior chamber (2) are placed at the same height.
8. Conveying installation according to one of claims 4 to 7, characterised in that the said beam (10) is provided with a plurality of rollers (17) capable of penetrating partially into rails (16) with a U-shaped cross section which can move in respect of height and extend over substantially the entire length of the said furnace.
9. Conveying installation according to one of claims 4 to 7, characterised in that the said beam (60) has an I-shaped cross section and is supported by rollers (67), which can move in respect of height and are fixed in respect of translation, penetrating partially between the flanges of said I-shaped section.
10. Vacuum furnace (1) comprising a conveying installation according to one of claims 4 to 9 or functioning according to the method of claims 1 to 3.