GB1584894A

GB1584894A - Combination of tunnel-type kiln and monolayer truck

Info

Publication number: GB1584894A
Application number: GB1151778A
Authority: GB
Original assignee: STUDICERAM SpA
Current assignee: STUDICERAM SpA
Priority date: 1977-03-24
Filing date: 1978-03-22
Publication date: 1981-02-18
Also published as: BE865279A; DE2717784A1; FR2385062B3; FR2385062A1; DE2717784C3; JPS53140306A; DE2717784B2

Description

(54) COMBINATION OF TUNNEL-TYPE KILN AND MONO-LAYER TRUCK (71) We, STUDICERAM S.p.A., an Italian joint stock company, of Via Matteotti 164 Agrate Brianza, Italy, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The present invention relates to a combination of a tunnel-type kiln and a mono-layer truck for carrying tiles and other ceramic products into and out of the kiln in a single layer.

Mono-layer tunnel-type kilns or furnaces are known, which kilns are mainly differen tiated one from another by the kind of means employed to transport the material to be baked.

According to a first type of conventional mono-layer tunnel-type kiln, the material to be baked is transported on a plurality of rotating rollers of ceramic material or special steel, arranged throughout the tunnel and forming a horizontal support, with the longitudinal axes of the rollers perpendicular to the direction of movement of the material to be baked. Kilns of this type have a serious drawback due to the restricted life of the rollers, in particular to those placed at the central zone of the tunnel, where the maxi mum working temperature is provided. In fact, as it is known, the temperature at this zone is higher than 1000 C, and generally about 1200"C. Thus the rollers are subjected to high stresses, especially because they are always in rotation and therefore are suscep tible to rapid wear and frequentjams.It is then necessary frequently to replace the rollers and, considering the fact that the materials of which they are made are particularly ex pensive, it follows that the maintenance of these kilns is uneconomic. Furthermore, the working breaks required to replace the rollers discontinue the operation of the kiln or furnace, which kiln however shows the highest efficiency when the operation is continuous.

Another type of conventional mono layer kiln employs as carrying means for transporting the material to be baked, trucks movable on rails and provided with a plurality of uprights having the same height, on which the material is caused to rest.

Kilns of this type have a significant drawback deriving from the difficulties and costs involved in designing special devices which allow the loading operation for the trucks to be carried out automatically. In general, movable arms are employed, with forkshaped ends which are adapted to remove the material from the moulding station and to place it onto the trucks, as well as to remove it from the truck when the baking or kilning is over.

Devices of this type are extremely complicated and difficult to control, mainly due to the fact that their movements have to be synchronised with those of the trucks. These in fact, as is known, are continually moving as the kiln operation is continuous.

Also in this case, therefore, the maintenance costs are high working breakdowns may often occur, due to failures of the loading means.

An additional drawback shown by this type of kiln derives from the fact that the trucks are unsuitable to carry ceramic products to be vitrified, for example in the case of "gres" stoneware. It is known that such products, as they reach the zones of highest temperature in the kiln, do not maintain the solid state, but change to a viscous state, and are thus easily deformable. The support afforded by the uprights is small and may cause the products to be deformed or otherwise to be damaged irreparably.

A further drawback is due to the fact that it is extremely difficult to obtain, with such uprights, a rest plane which is perfectly horizontal. Furthermore, the uprights must be made of special materials and are therefore very expensive.

Another type of known mono-layer kiln provides for a metallic conveyor belt as feeding means for the products to be baked.

Kilns of this type show great disadvantages limiting both the range of their use, and their life.

A first and important inconvenience is that the metallic conveyor belt can be employed only up to a certain temperature, which is usually considered to be about 1000"C as the upper limit. Above such a value it is necessary to adopt materials having particularly high qualities, which are therefore extremely costly.

A further drawback is due to the fact that, unavoidably, the metallic belt is subject to elongation, both through wear and because of the high temperatures within the kiln.

Therefore the belt does not remain perfectly level, and has to be replaced after a certain time. Also in this case, in addition to cost problems, interruptions of kiln operation have to be taken into account.

According to the present invention there is provided in combination, a tunnel-type kiln and a mono-layer truck for carrying tiles and other ceramic products into and out of the kiln in a single layer, which truck comprises: a frame mounted on a guide track; at least one pair of cross-members provided on the frame which cross-members are each formed with a plurality of recesses; and a plurality of rollers forming a support for the products, the rollers extending between the cross-members and being freely rotatable in the recesses thereof, the longitudinal axes of the rollers being parallel to the direction of movement of the truck into and out of the kiln.

Thus, the truck is simple to manufacture and is convenient for use in connection with whatevcr type of product is to be baked.

Moreover the loading and unloading operations may be made very readily as they can be completely automised. This is because a portion of the truck structure forms a part of the means for charging and discharging the products. Furthermore such means is extremely simple and hence of low cost and has a low susceptibility to breakdowns.

Further, the truck can be used at any temperature normally encountered in a tunnel-type kiln and has no particular wear problems.

For a better understanding of the present invention and to shown more clearly how it may be carried into effect reference will now be made, by way of example, to the accompanying drawing which shows one embodiment of a monolayer truck for use in a tunnel-type kiln together with a diagrammatic representation of means for charging and discharging products from the truck and of motor means for driving rollers on the truck.

With reference to the Figure, a truck for carrying tiles and ceramic products comprises a frame 1 with wheels 2, by means of which the truck can run on guide rails 3. The structure of the kiln tunnel and the means driving the truck therein will not be shown or described in detail, since the adoption of the truck according to the invention does not require any modification to conventional kilns.

The position at which the truck is illustrated is that where the material to be baked is charged and the already baked material is discharged.

The frame 1 is provided at opposite ends, with a pair of cross members 4 placed transversely with respect to the forward movement direction F of the truck within the kiln tunnel.

The length of the cross members 4 is the same as the width of the frame 1. The cross members 4 may be fixed to the shelf 1 in any known way, e.g. by a fit joint, which enables the cross members 4 to be removed from frame 1 when they need to be replaced. The material of the cross members 4 may be the same as that of the frame 1. In fact the properties and the quality of this material do not have to be particularly high, since the cross members 4, during the passage through the tunnel are not subjected to mechanical stresses, but only to thermal stresses. Each cross member 4 has, at its upper part, a multiplicity of housings 5, with a crosssection which is U-shaped in the illustrated embodiment, but which could also be of different shape, e.g. circular.

The housings or recesses 5 each have the same size, are equally spaced apart, and form the seats in which are inserted the ends of rollers 6 each having a longitudinal axis pardlel to the forward direction F of the truck in the kiln. The rollers 6 are rotatably mounted within the housings 5 and, as they all are at the same height with respect to the frame 1, form in this manner a rest and run plane for the products which are charged to and discharged from the truck.

The products, in the illustrated example, consist of paving tiles 7, coming in the direction of arrow Fl from a moulding station (not shown). The tiles 7 are carried by feeding means diagrammatically illustrated. This feeding means comprises, for each row of tiles, for example a pair of conveyor bands 8 which are driven at the truck side by driving pulleys 9, which co-operate with corresponding pulleys (not illustrated) at the moulding station. The driving pulleys 9 are all fixedly mounted on a single shaft 10 having fixed thereon another pulley 11 which is in turn connected by a driving belt 12 to pulleys 13 for rotating the various rollers 6 by means of a driving motor 14. It is clear that the pulleys 13, as well as the pulleys 9 and 11 could advantageously be replaced by gears and the bands 8 and the driving belt 12 by chains or cog belts. However these arrangements, as well as the various solutions to drive the bands 8 and belt 12 are not part of the present invention, but on the contrary relate to the usual expedients within the reach of one skilled in the art. Therefore they may be easily substituted by equivalent devices adapted to reach the same aim.

Referring again to the figure, a shaft 15 is coaxially fixed to each pulley 13 in correspondence with each roller 6. The longitudinal axis of each shaft 15 is the same as that of the associated roller 6. At the end of each shaft 15 there is provided a truncated-cone member 16 engageable within the hollow end of the associated roller 6. As the driving motor 14 is operated, the bands 8 are simultaneously driven forward, thus causing the tiles 7 to be carried onto the rollers 6 which are rotating, so that the tiles pass across the truck from the inlet to the outlet sides thereof. Each roller 6 is caused to rotate by the associated member 16 which substantially is one element of a clutch coupling. Also, in this case an equivallent solution could be provided, which is to be considered within the scope of the invention.

As the first line of tiles 7 reaches the outlet side of the truck, the drive motor 14 is stopped and the forward run of the truck into the tunnel, in the direction of arrow F, is started.

At the outlet of the tunnel where the products have been baked the truck is brought again to the position illustrated as in conventional kilns or furnaces. Then the discharge oper ation occurs, simultaneously with the already described charging operation, since the bands 8 and the belt 12 are synchronized. The baked tiles are fed to a conveyor belt 17 and are carried by the belt to a store.

One of the most important advantages afforded by the truck according to the inven tion derives from the fact that during all the time it is within the tunnel, the tiles do not contact any moving parts. The movement of the tiles relative to their support occurs only at the charge and discharge zone, where the temperature is substantially room temperature.

Therefore the stresses to which the various parts of the truck are subjected are substan tially zero and the truck shows a substantially reduced wear, so that it can be made with materials having no particularly high qual ities.

A further advantage of the truck according to the invention which in particular appears from the figure consists in the fact that its particular conformation allows the efficiency of the heating system for baking the material to be increased in comparison with the known trucks. In fact, as shown in the figure, especially in case of heat sources that are placed laterally, the cross members 4 form a stop wall preventing the combustion gases flowing directly to the outside through the chimney, thus increasing the period of time in which such gases are in contact with the material to be baked. Furthermore the zone between the rollers 6 and the frame 1 promotes the circulation of such combustion gases in a substantially transverse plane.

Still another advantage of the truck according to the invention consists in the fact that the rollers 6 allow the use of supporting plates for the material to be baked. This is particularly advantageous in connection with deformable materials such as "gress" stoneware.

It is obvious that the truck as above described and illustrated in the figure can be the subject of changes and/or modifications being considered as equivalents, without exceeding the protective scope of the invention.

WHAT WE CLAIM IS:- 1. In combination, a tunnel-type kiln and a mono-layer truck for carrying tiles and other ceramic products into and out of the kiln in a single layer, which truck comprises: a frame mounted on a guide track; at least one pair of cross-members provided on the frame, which cross-members are each formed with a plurality of recesses; and a plurality of rollers forming a support for the products, the rollers extending between the cross-members and being freely rotatable in the recesses thereof, the longitudinal axes of the rollers being parallel to the direction of movement of the truck into and out of the kiln.

2. A combination as claimed in claim 1, wherein the cross-members each comprise a bar of the same length as the width of the truck, the upper part of each of the crossmembers being formed with the recesses.

3. A combination as claimed in claim 1 or 2, wherein the ends of the rollers are adapted to engage corresponding rotatable means which is driven by a motor which also controls the feeding of the products to the truck in a direction transverse to the direction of movement of the truck into and out of the kiln.

4. A combination as claimed in claim 3, wherein the ends of the rollers are hollow for engagement with truncated cone-shaped ends of shafts driven by the motor for rotating the rollers so as to charge and discharge products from the truck simultaneously.

5. In combination, a tunnel-type kiln a a mono-layer truck for carrying tiles and other ceramic products into and out of the kiln in a single layer substantially as hereinbefore described with reference to the accompanying drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **.

usual expedients within the reach of one skilled in the art. Therefore they may be easily substituted by equivalent devices adapted to reach the same aim.

Referring again to the figure, a shaft 15 is coaxially fixed to each pulley 13 in correspondence with each roller 6. The longitudinal axis of each shaft 15 is the same as that of the associated roller 6. At the end of each shaft 15 there is provided a truncated-cone member 16 engageable within the hollow end of the associated roller 6. As the driving motor 14 is operated, the bands 8 are simultaneously driven forward, thus causing the tiles 7 to be carried onto the rollers 6 which are rotating, so that the tiles pass across the truck from the inlet to the outlet sides thereof. Each roller 6 is caused to rotate by the associated member 16 which substantially is one element of a clutch coupling. Also, in this case an equivallent solution could be provided, which is to be considered within the scope of the invention.

As the first line of tiles 7 reaches the outlet side of the truck, the drive motor 14 is stopped and the forward run of the truck into the tunnel, in the direction of arrow F, is started.

At the outlet of the tunnel where the products have been baked the truck is brought again to the position illustrated as in conventional kilns or furnaces. Then the discharge oper ation occurs, simultaneously with the already described charging operation, since the bands

8 and the belt 12 are synchronized. The baked tiles are fed to a conveyor belt 17 and are carried by the belt to a store.

One of the most important advantages afforded by the truck according to the inven tion derives from the fact that during all the time it is within the tunnel, the tiles do not contact any moving parts. The movement of the tiles relative to their support occurs only at the charge and discharge zone, where the temperature is substantially room temperature.

Therefore the stresses to which the various parts of the truck are subjected are substan tially zero and the truck shows a substantially reduced wear, so that it can be made with materials having no particularly high qual ities.

A further advantage of the truck according to the invention which in particular appears from the figure consists in the fact that its particular conformation allows the efficiency of the heating system for baking the material to be increased in comparison with the known trucks. In fact, as shown in the figure, especially in case of heat sources that are placed laterally, the cross members 4 form a stop wall preventing the combustion gases flowing directly to the outside through the chimney, thus increasing the period of time in which such gases are in contact with the material to be baked. Furthermore the zone between the rollers 6 and the frame 1 promotes the circulation of such combustion gases in a substantially transverse plane.

Still another advantage of the truck according to the invention consists in the fact that the rollers 6 allow the use of supporting plates for the material to be baked. This is particularly advantageous in connection with deformable materials such as "gress" stoneware.

It is obvious that the truck as above described and illustrated in the figure can be the subject of changes and/or modifications being considered as equivalents, without exceeding the protective scope of the invention.

WHAT WE CLAIM IS:- 1. In combination, a tunnel-type kiln and a mono-layer truck for carrying tiles and other ceramic products into and out of the kiln in a single layer, which truck comprises: a frame mounted on a guide track; at least one pair of cross-members provided on the frame, which cross-members are each formed with a plurality of recesses; and a plurality of rollers forming a support for the products, the rollers extending between the cross-members and being freely rotatable in the recesses thereof, the longitudinal axes of the rollers being parallel to the direction of movement of the truck into and out of the kiln.
2. A combination as claimed in claim 1, wherein the cross-members each comprise a bar of the same length as the width of the truck, the upper part of each of the crossmembers being formed with the recesses.
3. A combination as claimed in claim 1 or 2, wherein the ends of the rollers are adapted to engage corresponding rotatable means which is driven by a motor which also controls the feeding of the products to the truck in a direction transverse to the direction of movement of the truck into and out of the kiln.
4. A combination as claimed in claim 3, wherein the ends of the rollers are hollow for engagement with truncated cone-shaped ends of shafts driven by the motor for rotating the rollers so as to charge and discharge products from the truck simultaneously.
5. In combination, a tunnel-type kiln a a mono-layer truck for carrying tiles and other ceramic products into and out of the kiln in a single layer substantially as hereinbefore described with reference to the accompanying drawing.