EP0306837A1 - Electric furnace in particular for thermic treatment - Google Patents

Abstract

Electric furnace (1), in particular for the thermic treatment of pieces forming a charge (22) to be treated, comprising an external envelope (2) made of two couplable complementary parts which are movable in relation to one another, and, in this envelope, at least one support (23) for the charge to be treated and at least one electric heating element (3), the furnace comprising at least two parts (1a, 1b), its first part (1b) comprising the support (23) for the charge (22) to be treated and a first part (6) of said external envelope (2), and its second part (1a) comprising the second part (5) of said external envelope (2) and means (13, 14, 15) for displacing its two parts (1a, 1b) in relation to one another at least in the direction lateral to the charge (22) to be treated with a view to their coupling and their uncoupling, the first and second parts of the external envelope extending respectively over a part of the circumference of the charge to be treated so that the edges of its second part (5) are outside the path of the charge to be treated, and the second part (5) of the external envelope (2) extending, in the coupled position, above the charge to be treated so as to free the vertical access to the support for the charge when said parts (1a, 1b) of the furnace are uncoupled. <IMAGE>

Description

The present invention relates to an electric furnace in particular for the heat treatment of one or more parts forming a charge to be treated, optionally under pressure, under vacuum, or under controlled atmospheres.

Electric heat treatment furnaces of various types are currently known. Some, which include a front loading door, require the use of a loading and unloading support arm penetrating into the oven and have the disadvantage, during these maneuvers, of causing relative movements of the parts by compared to the others in particular when the latter constitute a mounted assembly to be treated.

Other ovens include a hearth receiving the load to be treated and a bell-shaped envelope covering the latter. For loading or unloading, one moves vertically, one relative to the other, either the sole or the bell. Other ovens also include a well-shaped enclosure open at its upper part and provided with a cover, the charge being introduced or extracted vertically through the upper opening. These known ovens have the particular disadvantage of requiring a large height available for the movement of their movable part and to allow their loading and unloading.

The present invention provides an electric oven whose structure makes it possible to avoid the drawbacks of known electric ovens and which has many advantages which will emerge later.

The electric oven, in particular for the heat treatment of parts forming a load to be treated, concerned by the present invention, comprises an outer casing in two complementary parts which can be coupled and which are movable relative to one another, and, in this casing, at least a support for the load to be treated and at least one electric heating element.

According to the present invention, this electric oven comprises at least two parts, its first part comprising the support of the load to be treated and a first part of said outer casing and its second part comprises the second part of said outer casing and means for moving its two parts relative to one another at least in the lateral direction to the load to be treated with a view to their coupling and their uncoupling, the first and second parts of the outer casing extending respectively over a part of the periphery of the load to be treated so that the edges of its second part are outside the path of the load to be treated, and the second part of the outer casing extending, in the coupled position, above the load to be treated so as to provide vertical access to the load support when said parts are uncoupled.

Said heating element generally extends between the load to be treated and said outer casing. In this case, in accordance with the present invention, this heating element is preferably in at least two parts respectively formed opposite said parts of said outer casing and associated respectively with said parts of the oven.

In certain cases, in particular in the case of cold-walled ovens, a thermal insulation screen can be provided between said electric heating element and said external envelope. According to the present invention, this screen is preferably in at least two parts which extend respectively opposite the parts of said outer casing and which are respectively associated with the two parts of the oven.

In a particular embodiment variant according to the present invention, said outer envelope is spherical and divided into two parts extending one above the other, its lower part being associated with the support of the load to be treated, the joint plane of said spherical outer casing preferably being an inclined diametral plane.

According to the present invention, said electric heating element and / or said thermal insulation screen are preferably respectively divided into two parts substantially in the region of the joint plane of said outer casing.

According to the present invention, said electric heating element and / or said thermal insulation screen are preferably substantially cylindrical and vertical, the joint plane of said outer envelope being such that their upper and lower planes extend, respectively, substantially, in the parts of the outer envelope.

The electric oven according to the present invention may further comprise at least one auxiliary device which extends or is arranged in the region of the horizontal median plane of said spherical outer envelope, between the latter and said vertical cylindrical heating element and / or said screen vertical cylindrical, this auxiliary device can for example comprise means for circulating a gas, possibly under pressure, in said outer casing and at least one heat exchanger. Other auxiliary devices can also be arranged in the largest free interior space facing the spherical exterior envelope.

According to the present invention and in an alternative embodiment, said means for moving the two parts of the oven relative to one another comprise on the one hand means for laterally moving these two parts in order to clear access vertical to the support of the load to be treated and on the other hand means for moving them vertically in order to couple or uncoupled them.

• - la figure 1 montre, selon une coupe médiane verticale, un four électrique conforme à la présente invention, en position fermée ;
• - la figure 2 représente, le four électrique de la figure 1, en position ouverte ;
• - et la figure 3 représente, en coupe horizontale par un plan médian, le four électrique de la figure 1, en position ouverte.

The present invention will be better understood from the study of a particular electric oven described by way of nonlimiting example and illustrated by the drawing in which:

• - Figure 1 shows, in a vertical median section, an electric oven according to the present invention, in the closed position;
• - Figure 2 shows, the electric oven of Figure 1, in the open position;
• - And Figure 3 shows, in horizontal section through a median plane, the electric oven of Figure 1, in the open position.

Referring to the figures, it can be seen that the electric furnace shown, generally identified by the reference 1, is formed in two parts 1a and 1b and comprises an outer casing generally identified by the reference 2 and, in this envelope, an electric heating element generally identified by the reference 3 and a thermal insulation screen generally identified by the reference 4 and disposed between the electric heating element 3 and the envelope exterior 2 which delimits an enclosure.

The outer casing 2 is composed of two semi-spherical parts 5 and 6 having a diametral joint plane 7 which extends perpendicular to the plane of FIGS. 1 and 2 and which is inclined approximately 30 ° relative to the vertical, the part 5 being above part 6. These semi-spherical parts 5 and 6, which respectively belong to parts 1a and 1b of the furnace 1, are double-walled 2a, 2b with a view for example to circulate between these walls a cooling fluid, their walls being respectively connected by annular rings or flanges 8 and 9 coming to bear one on the other in coincidence with the joint plane 7, the flange 9 having a recess 10 facing the flange 8 and likely to receive a seal.

The semi-spherical part 5 of the spherical outer envelope 2 is fixedly mounted on a chassis generally identified by the reference 11 while the lower part of its semi-spherical part 6 is fixed on a mobile chassis marked with generally by the reference 12. The chassis 12 carries at its lower part two pairs of rollers 13 and 14 capable of coming to bear on two horizontal parallel rails 15 of the chassis 11 so as to be able to move the semi-spherical part 6 of the 'spherical outer casing 2 parallel to the plane of Figures 1 and 2, in order to move it away from the closer to the semi-spherical part 5 fixed. On the frame 11 are fixed two pairs of jacks with vertical axes 16 and 17 whose upper ends of the rods 18 and 19 are adapted to engage in corresponding recesses of receptacles 20 and 21 fixed to the lower part of the movable frame 12, these jacks 16 and 17 being usable in the following manner.

When the movable part 1b of the oven 1, consisting of the movable frame 12 and the semi-spherical part 6 of the outer casing 2, bearing on the rails 12 by means of the pairs of rollers 13 and 14, is arranged to such that the flange 9 is placed in vertical correspondence of the half-spherical part 6 with the flange 8 of the half-spherical part 5 of the fixed part 1a of the furnace 1, the jacks 16 and 17 can be used to lift this part movable 1b so as to couple the two semi-spherical parts 5 and 6 of the spherical outer casing by the joint plane 7 and vice versa with a view to their uncoupling, the corresponding vertical stroke being relatively small compared to the diameter of the casing outdoor 2.

In the outer casing 2 is disposed a load support to be treated 22 which is constituted by a circular plate 23 whose upper face for receiving the load 22 is horizontal and whose axis coincides with the vertical axis of the envelope spherical outer 2. This load support 23, which is arranged in the lower part of the spherical outer casing 2 substantially at a quarter of its height and whose diameter is about a quarter of its diameter, is carried by vertical feet 24, the lower ends of which are fixed to the lower part of the semi-spherical part 6 of the outer casing 2, so that this load support 23 belongs to the movable part 1b of the furnace 1. The semi-spherical part 6 of the outer casing 2 therefore extends laterally to the load 22 and below and its semi-spherical part 5 extends laterally and above this load 22.

The electric heating element 3 is constituted in the example by two plates 25 and 26 of complementary shape delimiting a hollow cylinder with vertical axis coinciding with the vertical axis of the spherical outer casing 2, these parts 25 and 26 having vertical edges slightly spaced. This cylinder extends, at its lower part, around and at a distance from the peripheral edge of the load support 23 and upwards around the load to be treated 22, symmetrically with respect to the horizontal median plane of the furnace 1.

As can be seen in particular in FIG. 3, in section, the part 25 of the electric heating element 3 is located on the side of the semi-spherical part 5 of the spherical outer casing 2 and extends over a little more than half of the periphery of the load support 23, or of the load 22, symmetrically with respect to the plane of FIG. 1 , while its part 26 is located on the side of the semi-spherical part 6 of the outer envelope 2 and is complementary to its part 25.

The parts 25 and 26 of the electric heating element 3 are respectively carried by bars forming electric connections 27 and 28 which are respectively fixed on the semi-spherical parts 5 and 6 of the outer casing 2 and extend through , so as to belong respectively to the two parts 1a and 1b of the oven 1.

The parts 25 and 26 of the electric heating element 3 could, in variants, be subdivided and possibly include upper and / or lower parts extending above and below the load 22, the latter being respectively integral with the parts 25 and 26.

The thermal insulation screen 4, also in two parts, comprises a vertical cylindrical wall of the same axis as the cylindrical heating element 3. This cylindrical wall is in two parts 29 and 30 with joined vertical edges, which extend in vis-à-vis the parts 25 and 26 of the heating element 3 and which project upwards and downwards relative to the upper and lower ends of the latter substantially of the same length.

The insulation screen 4 further comprises an upper circular cover 31 which extends horizontally above the load 22 and which is fixed to the upper edge of the vertical part 29 as well as a lower cover 32 which extends horizontally below the load support 23 and which is fixed to the lower edge of the part 30, this lower cover 32 being traversed by the feet 24 of the load support 23.

It can be seen that the upper cover 31 extends in the semi-spherical part 5 of the outer casing 2 while the lower cover 32 extends in the semi-spherical part 6 of this casing, the covers 31 and 32 being respectively to distance from the upper and lower edges of the cylindrical heating element 3.

Part 29 of the insulation screen 4 and its upper cover 31 are carried by the semi-spherical part 5 of the spherical outer casing 2 by means of feet 33, so as to belong to part 1a of the oven 1.

Part 30 of the insulation screen 4 and its lower cover 32 are carried by the semi-spherical part 6 of the outer casing 2 by means of feet 34, so as to belong to part 1b of the oven 1 .

The thermal insulation screen 4 is made of a known material and structure, in particular metallic, composed of a set of superimposed layers, or of a thermal insulating material, adapted to the conditions of use of the oven.

In the closed position shown in FIG. 1, the two parts 1a and 1b of the electric oven 1 are coupled as described above, the movable frame 12 being carried by the rods 18 and 19 of the jacks 16 and 17.

To decouple these parts 1a and 1b from the oven 1, in order to unload a treated part 22 or to load another part 22 to be treated, it is possible to proceed as follows.

The actuators 16 and 17 are actuated so as to lower their rods 18 and 19. The furnace part 1b then descends until the rollers 13 and 14 come to bear on the rails 15 as we have seen previously. In doing so, the frame 12, the semi-spherical part 6 of the spherical outer envelope 2, the load support 23, the parts 30 and 32 of the thermal insulation screen 4 and the part 26 of the heating element. electric 3 go down and uncoupled from the corresponding parts of the oven part 1a. Using drive means not shown, such as drive means for rotating the rollers 13 and 14, the furnace part 1b is moved along the rails 15 away from it laterally from the furnace part 1a. to then arrive in the open position shown in Figure 2. In this position, the upper face of the load support 23 is accessible laterally LEMENT by the opening of the semi-spherical part 6 of the outer casing 2 and is also accessible vertically so that a load 22 to be treated or a treated load can be brought on or removed from the load support 23 by lateral or vertical displacement, for example using a carrying cable, without being hampered by a structural element of the oven, only the part 26 of the heating element 3 partially surrounding the support 23 of the load on less than half and the latter being vertically and laterally of the angle covered by the part 25 of the heating element 3 free of access. The same remarks apply to the thermal insulation screen 4.

To proceed with the coupling of parts 1a and 1b of the electric oven 1, the procedure is the opposite. It can be noted that in section the arcs covered by the parts 25 or 26 of the electric heating element 3 have vertical edges which neither hinder the passage of the load 22 disposed on the support 23 nor the passage of the latter.

The semi-spherical part 5 of the outer casing 2 is further equipped with a double-walled external connection pipe 35 for example for the connection of a suction device such as a vacuum pump.

The oven 1 is also equipped with an auxiliary device allowing a circulation of the gas inside the outer spherical envelope 2 and with a heat exchanger, generally identified by the reference 36, this device 36 being associated with part 1b of the furnace 1 and extending in the region of the horizontal diametral plane of the spherical outer casing 2 in which the distance separating the vertical wall 29, 30 from the thermal insulation screen 4 and the inner wall of the spherical outer casing 2 is the largest. Other devices could obviously be mounted in this area, both in the semi-spherical part 6 of the outer casing 2 and in its semi-spherical part 5.

As can be seen in FIG. 3, the auxiliary device 36 comprises a fan 37 whose axis extends along the horizontal axis of FIG. 1 and which extends through the wall of the semi-spherical part 6 of the outer casing 2 and which is carried by the latter, its helix 38 being in this semi-spherical part 6. On either side of the vertical plane of FIGS. 1 and 2, the auxiliary device 36 has two symmetrical tubular heat exchangers 39 and 40, the connection ducts of which, not shown, extend through the wall of the semi-spherical part 6 of the outer casing 2 so as to be connected to all other devices heat exchanges outside the furnace 1. In addition, the auxiliary device 36 has, in the furnace 1, partition walls which determine a passage 41 of forced circulation in the heat exchangers 39 and 40 by the propeller 38 of the fan 37, the covers 31 and 32 of the insulation screen 4 having vertical passages 42 and 43 for the circulation of gas around the load 22.

The present invention is not limited to the example described above. Indeed, one could have provided for a lateral displacement of the part 1b relative to the part 1a without initial vertical displacement. One could have provided part 1b of the stationary oven 1 and its movable part 1a. One could also have provided an outer casing 2, an electric heating element 3 and a thermal insulation screen 4 of totally different shapes, while allowing equivalent movements of these two parts and equivalent loading and unloading operations.

Claims (10)

1. Electric oven (1) in particular for the heat treatment of parts forming a load (22) to be treated, comprising an outer casing (2) in two complementary coupling parts movable relative to one another, and, in this envelope, at least one support (23) of the load to be treated and at least one electric heating element (3), characterized in that it comprises at least two parts (1a, 1b) of which its first part (1b) comprises the support (23) of the load (22) to be treated and a first part (6) of said outer casing (2) and its second part (1a) comprises the second part (5) of said outer casing (2) and means (13, 14, 15) for moving its two parts (1a, 1b) relative to each other at least in the lateral direction to the load (22) to be treated with a view to their coupling and uncoupling , the first and second parts of the outer casing extending respectively over a part of the periphery of the load to be treated so that the edges of its second part (5) are outside the path of the load to be treated, and the second part (5) of the outer casing (2) extending, in the coupled position, above of the load to be treated so as to free the vertical access to the support of the load when said parts (1a, 1b) of the oven are uncoupled. 2. Electric oven according to claim 1, characterized in that said heating element (3) extends between the load (22) to be treated and said outer casing (2) and is in at least two parts (25, 26) respectively formed opposite said parts (5, 6) of said outer casing (2) and associated respectively with said parts (1a, 1b) of the oven. 3. Electric oven according to one of claims 1 and 2, characterized in that it comprises a thermal insulation screen (4) which extends between said electric heating element (3) and said outer casing (2) , this screen being in at least two parts (29, 30) which respectively extend opposite the parts (5, 6) of said outer casing (2) and which are respectively associated with the two parts (1a, 1b) from the oven. 4. Electric oven according to any one of the preceding claims, characterized in that the said outer casing (2) is spherical and divided into two parts (5, 6) extending one above the other, its lower part (6) being associated with the support (23) of the load (22) to be treated. 5. Electric oven according to claim 4, characterized in that the joint plane (7) of said spherical outer casing (2) is an inclined diametral plane such that one of its parts (5, 6) extends laterally and above the load (22) and the other laterally and below the support of this load (22). 6. Electric oven according to any one of the preceding claims, characterized in that said electric heating element (3) and / or said thermal insulation screen (4) are respectively divided into two parts substantially in the region of the plane of seal (7) of said outer casing (2). 7. Electric oven according to any one of the preceding claims, characterized in that said electric heating element (3) and / or said thermal insulation screen (4) are substantially cylindrical and vertical, the joint plane (7) of said spherical outer casing (2) being such that their upper and lower planes extend, respectively, substantially, in the parts (5, 6) of the outer casing (2). 8. Electric oven according to any one of the preceding claims, characterized in that it comprises at least one auxiliary device which extends in the region of the horizontal median plane of said spherical outer casing (2), between this outer casing and said vertical cylindrical heating element (3) and / or said vertical cylindrical thermal insulation screen (4). 9. Electric oven according to claim 8, characterized in that the auxiliary device comprises means (36) for circulating the gas in said outer casing and at least one heat exchanger. 10. Electric oven according to any one of the preceding claims, characterized in that the said means for moving the two parts (1a, 1b) of the oven with respect to each other comprise on the one hand means (13, 14, 15) for laterally moving these two parts in order to clear the vertical access to the support of the load to be treated and on the other hand means (16, 17) for moving them vertically in order to couple or uncoupled.

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