EP0002052A1 - Method and device for conveying supporting plates through a tunnel kiln - Google Patents

Abstract

The invention relates to the continuous movement in tunnel ovens of hobs. The plates (S1, S2, S3) which are pushed into the oven roll on rows of balls (b) by means of protruding pads (p) formed on the lower surface of the plates and separated from each other by parts in hollow (c). The invention is particularly applicable to the firing of ceramic parts at high temperature.

Description

The present invention relates to a method and a device for ensuring the displacement in tunnel ovens, in particular for the firing at high temperature of ceramic products, of cooking plates which pass through the oven while supporting the products to be cooked. More precisely, the invention relates to applications to ovens of the type according to which the entire row of plates which roll on balls supported in raceways is pushed at one end of the oven, while parallel grooves of the same spacing as said paths are formed on the underside of the plates to receive the balls which simultaneously provide lateral guidance of the plates.

Such an oven has been described in particular in French patent 2,135,711 (registration number 71 14 723) filed in the name of Mr. Sten CHRONBERG and in the Certificate of Addition No. 2.180.221 (registration number 72 13 030) to this patent.

Although compared to the known devices, the installations described in the mentioned patent and in its Certificate of Addition have undeniable advantages, various difficulties appear in practice, in particular in as regards the more or less irregular rolling of the balls in the oven the risks of overlapping although rare but not completely removed from the plates, the loss of a certain number of balls in the oven and the production in the baking volume of the oven of unwanted dust entrained by the balls.

According to the method of the invention which uses baking plates which pass through the oven while rolling on balls guided in raceways, in order to limit the frictional forces, said plates are supported by a limited number of said balls which roll in said raceways and in parallel grooves of the same spacing formed on the underside of the plates, providing in said grooves more hollow and more protruding parts so that when a ball passes under a said projection it locally supports a plate by simultaneously releasing at least the largest part of the load the balls of the same raceway, possibly located near said projection under a said part more hollow. In this way a better rolling of the plates is carried out which roll on a limited number of just sufficient balls, one avoids pushing simultaneously in their race a large number of balls which do not work and which only cause a braking of the movements of advanced plates, abrasion of the balls between them and risk of derailment. Also in this way, the flow rate of the balls passing through it per unit of time is considerably slowed down in the oven, limiting friction, the causes of wear and the thermal inertia of the balls, the temperature of which necessarily follows the temperature rise curve and temperature reduction of the tunnel oven along its path.

The invention also relates to a device allowing the implementation of the aforementioned method, this device being characterized in that the raceways in which the balls roll being substantially horizontal, the grooves formed on the underside of the plates parallel to said paths include more protruding parts forming pads on which said plates roll when a ball is present in the raceway in line with a said pad.

Advantageously, at least one pad is preferably provided on each side of said plates on either side of the median plane parallel to the direction of advancement of the plates and at least three pads are provided for each plate. Thus each plate is usually supported by three pads which each roll on a ball which advancing at half the speed of the plate is replaced after a certain distance by another ball present in the raceway and as will appear later.

According to another variant of implementation of the invention particularly suitable for transporting heavy loads, there are provided under said plates a greater number of pads which are mounted attached in said grooves formed under the plates and in which they have a certain clearance in particular vertical. Thus, depending on the arrangement of the load on the plate and depending on the advancement of the plate in the oven, a certain number of pads in turn will support the load by rolling on the underlying balls, other pads not working because of of the expected vertical clearance.

The invention will appear more clearly with the aid of the description which follows, made with reference to the drawings. attached illustrating by way of example various embodiments.

• La figure 1 est une vue schématique en coupe verticale à travers un four tunnel comportant des plaques de cuisson avançant sur des rangées de billes; la figure 2 est une vue en coupe longitudinale faite à plus grande échelle et avec arrachement le long d'un four tunnel sensiblement dans le plan d'un chemin de roulement de billes comme repéré II -II dans la figure 3 ; la figure 3 est une vue en coupe horizontale faite par-dessous sensiblement par le plan III - III de la figure 2 et illustrant les deux chemins de roulement parallèles supportant les plaques de cuisson ; la figure 4 est une vue en coupe verticale faite dans le plan IV - IV repéré aux figures 2 et 3 ; la figure 5 est une vue partielle montrant comme la figure 3 une variante de réalisation des gorges formée sous les plaques support de cuisson ; la figure 6 est une vue en coupe faite suivant le plan VI - VI de la figure 5 ; la figure 7 est une vue en coupe verticale longitudinale faite à travers un chemin de roulement et montrant comment on le réalise ; la figure 8 est une vue en coupe transversale selon le plan VIII - VIII de la figure 7 illustrant avec cette figure un procédé permettant la fabrication de ces chemins de roulement ; la figure 9 est une vue en coupe longitudinale parallèlement à un chemin de roulement du four et avec arrachements illustrant comme la figure 2 une autre réalisation particulièrement adaptée au transport de charges lourdes ; la figure 10 est une vue en coupe transversale faite selon le plan X - X de la figure 9 transversalement à une plaque support roulant sur ces chemins de roulement ; la figure 11 est une vue en coupe semblable à celle de la figure 10 montrant une variante de réalisation des patins ; la figure 12 est une vue en perspective éclatée montrant une manière de réaliser les chemins de roulement utilisés dans les réalisations des figures 9 à 11.

In these drawings:

• Figure 1 is a schematic view in vertical section through a tunnel oven having cooking plates advancing on rows of balls; Figure 2 is a longitudinal sectional view taken on a larger scale and with cutaway along a tunnel oven substantially in the plane of a ball raceway as marked II -II in Figure 3; Figure 3 is a horizontal sectional view made from below substantially by the plane III - III of Figure 2 and illustrating the two parallel raceways supporting the cooking plates; Figure 4 is a vertical sectional view made in the plane IV - IV identified in Figures 2 and 3; Figure 5 is a partial view showing like Figure 3 an alternative embodiment of the grooves formed under the cooking support plates; Figure 6 is a sectional view taken along the plane VI - VI of Figure 5; Figure 7 is a longitudinal vertical sectional view taken through a raceway and showing how it is made; Figure 8 is a cross-sectional view along the plane VIII - VIII of Figure 7 illustrating with this figure a process for the manufacture of these raceways; Figure 9 is a longitudinal sectional view parallel to a rolling track of the oven and with cutaway illustrating like Figure 2 another embodiment particularly suitable for the transport of heavy loads; Figure 10 is a cross-sectional view taken along the plane X - X of Figure 9 transversely to a support plate rolling on these che rolling mins; Figure 11 is a sectional view similar to that of Figure 10 showing an alternative embodiment of the pads; FIG. 12 is an exploded perspective view showing a way of producing the raceways used in the embodiments of FIGS. 9 to 11.

We will first refer to Figure 1 schematically illustrating a tunnel oven comprising support plates S rolling on balls b themselves guided on two unwinding paths 1, 2. The plates S support products to be cooked 3 in the heated enclosure 4 of the oven, the insulating wall of which is marked 5. In 6, heating means have been identified, for example by radiation.

As previously mentioned, difficult bearing problems to be solved appear in such an oven. These problems are solved according to the invention as will now be described.

According to the embodiment illustrated in FIGS. 2 to 4, the support plates S, of which three marked S1, S2, S3 are visible, are formed, on their lower face (see FIG. 4) with grooves 7, 8 parallel and of the same spacing as the raceways 9, 10 in which the balls roll b. In addition these grooves 7, 8 have more projecting parts forming pads p and more hollow parts c.

In the example illustrated and as it appears more clearly in FIG. 3, each support plate S is formed with three pads, such as p1, p2, p6 for the plate S1 and p3, p7, p8 for the plate S2, these pads being arranged in staggered rows creating a load-bearing triangle favorable for the plate. Two pads such as p1-p2, p7-p8 on one side of the plate are separated by a hollow c1, c7, while each pad isolated on the other side such as p6, p3 is surrounded by two hollow parts such as c5-c6, c2-c3.

Regarding the raceways 9, 10 these are formed by gutters, as horizontal and continuous as possible. In the example illustrated, these ceramic gutters such as the balls b and the cooking plates S are mounted end to end with their ends interlocking by half-thickness fingerings as will be described in more detail in FIG. FIG. 2 shows three gutters g1, g2, g3 forming part of the raceway 9, and in FIG. 4 a gutter g7 forming part of the other raceway 10.

The gutters g are supported on the hearth of the oven (not shown) by the rails or paths 11, 17 which at the same time prevents them from turning thanks to the provision of tenons 12 projecting from the support surface 13 of the gutters at each end d 'them and entering a mortise 14 (Figure 7) corresponding to the gutter.

On the other hand, as it clearly appears in FIG. 2, each support plate S is formed at one end with a bevelled part 15 which penetrates into a corresponding hollow part 16 adjacent to the next plate. There is thus obtained a certain embedding of the ends of the plates one inside the other during their advancement in continuous thrust in the furnace.

The operation of the device will now be explained.

The plates advancing in the oven being pushed in the direction of arrow A (Figures 2 and 3), each plate as S1 pushes the next S2 and so S3 suite, etc.

Each time a new plate S is introduced into the oven, a number of balls are simultaneously introduced into the raceways 9, 10, for example a ball on each side each time a plate is introduced.

Assuming as illustrated in Figures 2 and 3 that at a given time the plate S1 is supported by its three pads p1, p2, p6 by rolling on three balls b1, b4, b14 we will describe what happens in the movement d advancement of the support plate S1.

It appears first of all that the balls such as b2, b3, b13, b15, b16, b17 located under recessed parts c1, c5, c6 of the plate S1 will not be affected by the movement of the plate S1 as long as 'they will remain under these hollow parts without contact with the plate S1. These balls therefore remain stationary. On the other hand, the three balls b1, b4, b14 which support the plate S1 advance at the same time as this plate by rolling under them and at half the speed of advancement of the plate. This will happen as long as the balls are under the skates. Advantageously, a shoe length of the order of 3 to 5 times the diameter of a ball will be chosen. In one embodiment, the balls are 10mm in diameter, the pads and the recesses having lengths of the order of 40mm.

Under these conditions when the plate S1 advances by a length equal to that of twice the length of a skate, the support balls of the plate which roll under the skates advance by the length of a skate and therefore leave it to fall under a adjacent hollow. Simultaneously in this movement each skate such as p1, p2, p6 will find another ball in front of it such that b2, b5, b15 waiting under the adjacent hollow cl, c2, c6. The taking of a ball under the shoe and its exit from the shoe are facilitated by joining parts 18, 19 (FIG. 2) forming inclined ramps.

In order to facilitate reading of the figures, FIG. 3 shows in broken lines the balls at rest such as b2, b3, b5 which do not roll being under hollow parts of the support plates S, and in solid lines the balls such as b1, b4, b7 which roll and support the plates by their pad p.

If by chance one of the pads or several pads of a plate is momentarily devoid of underlying balls, for example no ball b7 not being under the pad p3, it appears that the plate S2 remains however horizontal due to the fitting of the conjugate ends 15, 16 of the adjacent support plates. In other words, if one of the plates is not temporarily and locally supported by balls rolling under them, they remain supported by the adjacent plates.

Finally, on the other hand, the clearances are thus calculated that if by chance an absence of balls occurred simultaneously under the pads of several adjacent plates, then the plates would roll on the balls present in the recesses c without the plates coming to bear directly on the surface of the raceways or on the sides of the oven. Such a bearing could only be of very short duration because very quickly balls would again be present under pads.

In the embodiment which has just been described, it will be observed that the width of the rolling grooves with their parts more hollow c and their parts in skid p is substantially equal to the diameter of the balls. With regard to the width of the raceway the gutters g will have a slightly larger diameter than that of the balls so as to ensure good rolling and simultaneously correct lateral guidance of the plates.

According to the variant embodiment illustrated in FIGS. 5 and 6, the hollow parts c ′ of the support plates S ′ are given a width greater than that of the pads p which remains substantially equal to the diameter of the balls. In this way, the balls such as b5, b6, b8, b9 are not entrained with more certainty when they are in their race under hollow parts such as c'2, c'3. Simultaneously, good lateral guidance of the support plates S 'is retained by the pads of reduced width such as p3.

Figures 7 and 8 illustrated in more detail the gutters g1, g2, g3 constituting the active part of the raceway receiving the balls. Each gutter g is formed from an inner ceramic tube 20 on which is sealed a ceramic tube 21 also of slightly larger diameter and the same length with a longitudinal offset 1. The composite tube thus produced can then be cut, for example with a grinding wheel 22 as illustrated in FIG. 8 along a diameter to leave the gutter g. At each end, it is also possible to provide a mortise 14 for engaging the post 12 (FIGS. 2 and 4) avoiding the rolling of the gutters on their supports 11, 19. The longitudinal offset 1 of the tubes 20, 21 provides a connection by interlocking at half-thickness of the gutters g forming end-to-end the raceway of the balls.

We will now refer to Figures 9 and 10 in which have illustrated another embodiment of the invention particularly suitable for transporting heavy loads in an oven.

While in the embodiments described above the pads formed in the grooves formed on the underside of the support plates were directly part of said plates, in the embodiment of Figures 9 and 10 the pads are mounted attached in said grooves in which they have a certain play in particular vertical.

More precisely, in each support plate which can be relatively thick such as S11 are formed two grooves 30, 31 parallel to the raceways of the balls and in which grooves are added pads such as p11, p21 (FIG. 10) mounted captive in said grooves but with a certain vertical clearance.

In the example illustrated, each support plate S comprises on each side four pads thus mounted, such as p11, p12, p13, p14 (FIG. 9). The pads cannot escape out of said grooves thanks to the provision of end-locking pieces 32, 33 for example of ceramic suitably cemented at the ends of said grooves.

With regard to the actual tracks of the balls, these are formed by ceramic gutters such as 34, 35, 36, 37 mounted end-to-end and kept in alignment by any suitable means such as keying also ceramic 38 (Figures 9 and 12); these gutters are themselves supported on rails or raceways 39, 40 and prevented from turning thanks to grooves 41 suitably engaged on the support rails 39, 40.

The operation of the device is as follows.

When the plates advance in the direction of arrow A (FIG. 9) while being all pushed against each other by the first introduced into the oven, each plate such as for example that S11 encounters under its skids a certain number of balls which roll in the underlying raceways. Due to the relatively large loads (not shown) placed on the support plates S, these deform more or less and work in bending and torsion. Under these conditions, and depending on the clearances of the raceways, balls of different diameter, etc. each support plate S is supported at a given time by only a certain number of its pads, for example the pads p11 and p14 for the plate S11 as regards the raceway 39, these pads rolling on two balls b30, b33. These pads are therefore applied to the bottom of the corresponding groove 30 of the plate S11. On the contrary, the other two pads p12 p13 of this same plate and of this same groove are somewhat lowered not supporting the plate S11. On the other hand, they are applied by their weight to the balls b31, b32 present at this location on the raceway. It follows that in the path of advancement of the plate S11, all the balls b30, b31, b32, b33 present under the pads p11 to p14 simultaneously advance at half the speed of that of the plate.

We understand that in this way we ensure a very good equal distribution of the balls in the oven along the raceways, we avoid their stagnation in the oven and we ensure a regular successive work when they pass from one skid to the next .

The variant embodiment illustrated in FIG. 11 shows a plate S'11 with pads p'12 p'21 con formed a little differently but they too mounted prisoners in grooves 30 ', 31' according to the same operating principle.

Of course, numerous variants of implementation and of construction can be made.

Thus, for example, in the “heavy” embodiment described in FIGS. 9 to 11, it has been assumed that all of the pads were substantially the same height. If desired, they could be given different heights or, more generally, be arranged so that when the added pads are all resting at the bottom of the groove, they are not substantially level on the same plate. In this way, higher pads would be created locally which would normally support the plates, which can be arranged for example at three points of a triangle a little as illustrated in the embodiment of FIG. 3.

The invention therefore includes all the technical equivalents of the means described as well as their combinations if these are carried out according to the spirit and implemented in the context of the claims which follow.

Claims (11)

1. Method for ensuring the displacement in tunnel ovens in particular for the firing at high temperature of ceramic products, of cooking plates which pass through the oven while supporting the products to be cooked, oven of the type according to which one pushes at one end of the oven the entire row of plates which roll on balls supported in raceways, while parallel grooves of the same spacing as said paths are formed on the underside of the plates to receive the balls which simultaneously provide lateral guidance of the plates,
characterized in that in order to limit the frictional forces, said plates are supported by a limited number of said balls which roll in said raceways and in said grooves, leaving hollow parts on the underside of the plates in said grooves and no longer projecting so that when a ball passes under a said projection it locally supports a plate by simultaneously releasing, from at least the greater part of the load, the balls of the same raceway possibly located near said protrusion under a said more hollow part. 2. Device making it possible to ensure movement in tunnel ovens, in particular for the high-temperature cooking of ceramic products, of cooking plates which pass through the oven while supporting the products to be cooked, an oven of the type according to which one pushes at one end. of the oven the entire row of plates which roll on balls supported in raceways while parallel grooves of the same spacing as said paths are formed on the underside of the plates to receive the balls which assu simultaneously provide lateral guidance of the plates, device for implementing the method according to claim 1,
characterized in that said raceways being substantially horizontal, said grooves formed on the underside of said plates have more protruding parts forming pads on which roll said plates when a ball is present in the raceway plumb of a said skate. 3. Device according to claim 2,
characterized in that at least one shoe is preferably provided on each side of said plates on either side of the median plane parallel to the direction of advancement of the plates. 4. Device according to claim 2 or claim 3,
characterized in that at least three pads are provided for each plate. 5. Device according to one of claims 2 to 4, characterized in that the length of each shoe is preferably of the order of 3 to 5 times the diameter of the balls. 6. Device according to one of claims 2 to 5, characterized in that said pads are formed directly by the lower part of the plates. 7. Device according to one of claims 2 to 5, characterized in that said pads are mounted reported prisoners in said grooves in which they have a certain clearance, in particular vertical. 8. Device according to claim 7,
characterized in that said pads added when they are supported at the bottom of their throat are all substantially level on the same plate. 9. Device according to claim 7,
characterized in that said pads added when they are in support at the bottom of their groove are not all substantially level on the same plate. 10. Device according to one of claims 2 to 9, characterized in that said raceways are formed by half ceramic tubes, the ends of which interlock with grooves and tongues, half-thickness flange or the like. 11. Device according to one of claims 2 to 10, characterized in that said plates are formed at their adjacent edges with corresponding interlocking parts, for example with tenon and mortise, groove and tongue, cooperating grooves or analogs.

Images