GB2113639A

GB2113639A - Plant for firing ceramic articles

Info

Publication number: GB2113639A
Application number: GB08232001A
Authority: GB
Inventors: Renato Bossetti
Original assignee: SITI
Current assignee: SITI
Priority date: 1981-11-27
Filing date: 1982-11-09
Publication date: 1983-08-10
Also published as: BR8206865A; DE3243695A1; IT1140307B; IT8125333A0; FR2517295A1

Abstract

Plant for the firing treatment of ceramic articles of manufacture provides for the continuous circulation of charge-carrying plates, which serve as supports for the articles, around a closed circuit. Around this closed circuit, there are provided article loading and unloading stations 11, 12 to and from the charge-carrying plates. The circuit is defined by a conveyor T constituted at least in part by pairs of spaced apart, pulley driven belts. Automated means are provided along the conveyor to load and unload the articles of manufacture to and from the charge-carrying plates. A storage unit 17 for loaded charge- carrying plates is arranged over the conveyor T, and pivotting transfer means 4 are provided between the legs of the conveyor circuit. <IMAGE>

Description

SPECIFICATION Method and a system for the firing treatment of ceramic materials Ceramic article-of manufacture manufacturing processes are known to include a firing operation which is directed to completely remove the water retained in the claysh components being used and convert them into the corresponding anhydrous compounds. The firing furnaces employed, for reasons of energy saving, especially in view of consumption rates at the start, are mostly operated, in ceramic material production plants, continuously. On the contrary, operations carried out upstream and/or downstream of the furnace, such as forming and preparing the blanks for firing, or the sorting of the articles of manufacture after firing and their storage or packaging, are operations which only take place during worktime, and accordingly performed on an intermittent basis.

For this reason, in ceramic article production plants, temporary storage systems have been proposed and used which allow accumulation of the blanks from the forming step and their continuous feeding to the furnaces, or viceversa, continuity of discharge of the articles from the firing furnaces and their storage, even during periods of inactivity of the upstream or downstream devices, which periods depend on intentional or incidental shut-offs of said devices.

With particular reference to plate-like ceramic articles, which for convenience of illustration will be generally referred to as tiles hereinafter, such storage systems may comprise special construction carriages, such as those described in parallel studies by the same Applicant.

During the firing treatment in the furnace, the tile blanks, which are fed in their raw state (pressed, extruded, etc.), are transported through the furnace while carried in more or less multitudinous groups on specially provided "trays" or charge-carrying plates whose function is that of preserving the shapes of the raw tiles by preventing their deformation.

In the cited events of shut-offs of the devices located upstream and downstream of the furnaces, said charge-carrying plates are unloaded together with the tiles they are carrying onto the cited temporary storage carriages, where they are left throughout the interruption period of time, so that they withdrawn from the active processing cycle.

Thus, the continuity of the furnace treatment cycle during such periods requires an abundant availability of charge-carrying plates for the continued feeding of fresh charges of raw tiles to the furnace, which availability should take into due account periods of inactivity of certain sections of the plant which may be prolonged. Of course, such abundant availability of charge-carrying plates involves high investment costs.

As a consequence, carriage requirements also increase for the temporary storage of the blanks, their capacity being largely saturated by reason of the charge-plates being accumulated therein during the aforesaid shutoffs.

Thus, investment costs are further aggravated by the increased requirements for said storage carriages.

An added disadvantage connected with the use, during the above shutoffs, of a high number of charge-carrying plates resides in an increased power consumption brought about for their heating during the firing treatment in the furnace.

It is a primary object of this invention to provide a method and a system of firing ceramic materials, in particular ceramic tiles, which afford implementation of the processing cycle on a continuous basis, regardless of the duration of processing shutoff periods upstream and/or downstream of the firing treatment station, and with substantially reduced requirements for charge-carrying plates.

Another object of the invention is to provide a method and a system of firing ceramic materials, which also afford significant energy savings in the conduction of the processing cycle.

A further object of this invention is to provide a system for firing ceramic materials which can also take in certain imbalances in the operation of the system as deriving from possible incidental shutoffs.

A not unimportant object of the invention is to provide a system as indicated which involves reduced investment costs, not only on account of the decreased requirements for charge-carrying plates but also for temporary storage carriages.

These and other objects, such as will be apparent hereinafter, are achieved, according to one aspect of this invention. by a method for the firing treatment of ceramic articles of manufacture, characterized in that it comprises the steps of feeding into a furnace raw blanks carried on charge-carrying plates, said charge-carrying plates being caused to circulate continuously through a closed circuit path, of passing said charge-carrying plates, as carrying fired articles, through at least one automated article discharging station, and discharging said articles, of feeding said chargecarrying plates to at least one automated loading station to load raw blanks thereon, and of returning said charge-carrying plates through said furnace.

According to a further aspect of this invention, there is provided a system for the firing treatment of ceramic materials, which comprises a treatment furnace, wherethrough said ceramic materials are transported carried on a plurality of charge-carrying plates, said system being characterized in that it comprises an apparatus for continuously moving said charge-carrying plates through a closed circuit path also going through said furnace, and means along said closed circuit path for loading onto said charge-carrying plates and unloading from said charge-carrying plates said ceramic materials.

Further features and advantages of the invention will be apparent from the following description of a preferred but not limitative embodiment of the method and system according thereto, with reference to the accompanying drawings, where: Figure 1 is a schematical plan view of the system according to this invention; Figure 2 is a side elevation showing schematically the system of Fig. 1, as viewed from the side of the loading and unloading means; Figure 3 illustrates the means for loading the charge-carrying plates according to this invention, as viewed across the direction of movement of the plates; Figure 4 is a plan view of the transfer means between the various segments of the conveyor according to the invention; Figure 5 is a side elevation showing sche maticaily the means of Fig. 4 during their movement to pick up the charge-carrying plates;; Figure 6 is a plan view illustrating the rotary movement of the transfer means of Figs. 4 and 5; and Figures 7 and 8 schematically illustrative the movement of the transfer means in depositing the charge-carrying plates onto an adjoining segment of the conveyor.

Making reference to the drawing figures, indicated at 1 is a firing treatment furnace, to which the method of this invention can be applied, and which may be incorporated to a system according to the invention. While being applicable to any conventional type of furnace currently in use, the invention preferably applies to a single-firing furnace having one or more channels, wherein a plurality of firing chambers or channels are provided which may be arranged side-by-side or superimposed, through which roller conveyors feed the ceramic articles of manufacture forward, which will be termed tiles hereinafter for convenience of illustration.

The system of this invention primarily comprises an apparatus for continuously moving charge-carrying plates through a circuit path which is closed through the furnace 1 and feeds and discharges all the channels of a multi-channel furnace in succession, according to a preset program or under control, as explained hereinafter.

The apparatus for moving the charge-carrying plates through a closed circuit path comprises a conveyor T connecting, in an external path to the furnace, the furnace outlet 2 to the furnace inlet 3, going through some operative stations, as described more clearly hereinafter.

The conveyor T, while it may have sections in the form of a conveyor belt or conveyor rollers, preferably comprises, according to an advantageous embodiment of the invention, pairs of laterally spaced apart belts, such belt pairs being suitably driven by and carried on pulleys mounted in the apparatus frame. The charge-carrying plates are carried on respective belt pairs such as to present side portions which protrude out of the two belts.

The apparatus for moving the change-carrying plates according to the invention comprises, at different segments of the conveyor lying at an angle to or out of level with, transfer means 4 for the charge-carrying plates between said different segments. Such transfer means, schematically indicated in Figs. 4 to 8, comprise a yoke element 5 mounted for rotation about a vertical hinge 6.

The rotational movement is ensured by a drive means 7.

The yoke 5 is rigid with a sleeve 8 which fits into an upright 9 of the system frame.

Drive means (not shown) move the sleeve 8 along the upright 9, thus imparting to the yoke 5 a vertical translatory movement.

The cross dimension or span of the yoke 5 is expediently provided to permit the yoke to cooperate with the pairs of conveyor belts of the segments wherebetween the transfer takes place, the yoke being enabled to move, in its upward or downward translatory movements, through the spaces between the belt pairs or externally thereto, to engage those portions of said charge-carrying plates which protrude out of the belts.

With special reference to Figs. 5 to 8, the illustrated sequence of movements comprises the upward movement of the yoke 5, which engages with the side protruding portions of the oncoming charge-carrying plates on the segment P of the conveyor and picks them up by lifting them above the conveyor plane.

Then, the yoke is rotated through 90 to set it parallel to the following segment R of the conveyor, and is next shifted downwardly.

During the downward movement of the yoke 5, the charge-carrying plates are caught and picked up by the end portion of the segment R of the conveyor passing between the yoke arms which then causes them to move on along the preset path.

Advantageously, the end portion of at least one of the segments between which the transfer means 4 are active, and in the embodiment specifically shown, the end portion of the segment R, is made in the form of a movable end portion 10 which is displaceable vertically for a more flexible cooperation with the yoke 5.

Conventional drive means (not shown) are provided for controlling the movement of said movable arm, e.g. by acting on a sleeve rigidly attached to the arm 10 and guided along an upright similarly to what has been described in relation to the translatory movement of the yoke 5, to permit relative movement between the yoke and movable arm and return said arm into alignment with the remaining portion of the segment R.

While in the specific embodiment of the system according to the invention illustrated in Figs. 1 and 2 two such transfer means 4 are shown between the segments P and R, respectively R and S, of the conveyor, it is apparent that there may be several points where the presence of such transfer means 4 becomes necessary, depending on each specific path which a conveyor according to the invention is caused to follow.

In particular, transfer means 4 as described above are used also at the inlet 3 and outlet 2 of the multi-channel furnace 1 (not shown in the drawings), for the purpose of loading and unloading the charge-carrying plates carrying the tiles from the various superimposed shelves of the furnace.

Along the closed circuit path of the chargecarrying plates, and in particular at the segment R of the conveyor, means 11 are provided for loading raw tiles onto the chargecarrying plates, and respectively means 1 2 for unloading the fired tiles from the chargecarrying plates. Advantageously, a plurality of such loading, respectively unloading, means may be used, for alternate operation or replacement in the event of shutoffs owing to failures, maintenance operations, etc. In that case, as shown in the figures, the auxiliary loading means 11' and unloading means 12' would be inserted in the closed circuit of the charge-carrying plates by means of bypassing segments U of the conveyor. The loading means 11, for instance are described more fully with reference to Fig. 3.As shown in that figure, the raw tiles 13, oncoming on a feeding conveyor device E, also comprising a pair of belts, are positioned at the loading station above a supporting member 1 4 which can be reciprocated up and down by suitable means, e.g. cam means (not shown).

When moved upwards, the supporting member 14 raises the raw tiles 1 3 to the level of the top surface of the charge-carrying plates 1 5 fed on the conveyor T as far as the loading station 11. A specially provided rack 16, driven for example by a chain, in turn driven by a gear motor of the like system, moves the raw tiles carried on the supporting member 14 to transfer them onto the plates 15.

Of course, the movement of conveyor T at the loading station 11, conveyor E, supporting member 14, and rack 16 is suitably synchronized, e.g. by means of a photocell control, to accomplish the described sequence in the correct order.

The unloading station comprises the unloading means 1 2 and is constructed exactly like the loading means 11 described above, excepting that the rack is arranged at a mirrorlike position with respect to the position of the loading means 11 such as to produce during its active stroke, the transfer of the fired tiles from the charge-carrying plates 1 5 to an identical supporting member 1 4 associated with a belt conveyor F for transporting the fired tiles toward specially provided storage stations.

Advantageously, the apparatus for moving the charge-carrying plates 1 5 according to the invention comprises, included in the closed circuit path of the charge-carrying plates, a compensating or storage unit station capable of taking in unbalances due to incidental shutoffs of the apparatus and of ensuring feeding continuity for the charge-carrying plates carrying the raw tiles to the treatment furnace.

Advantageously, the compensating or storage unit device 1 7 comprises a tunnel chamber 1 9 wherein an auxiliary endless chain conveyor 18 is arranged to which a plurality of containers are attached each having plural shelves for accommodating a substantial number of charge-carrying plates and raw tiles loaded thereon. In the event of failure or shutoffs along the conveyor T, this storage unit is operated which, owing to the movement of the chain conveyor 18, can assure continuity in the delivery of charge-carrying plates and raw tiles from the outlet of the tunnel chamber 1 9 onto the operating section of the conveyor T or alternatively onto a bypass section of the conveyor (not shown), for their delivery to the furnace 1.Depending on the size of the storage unit and its capacity, it will be able to accommodate longer or shorter shutoff periods of the main conveyor T.

Advantageously, the tunnel chamber 1 9 of the storage unit 1 7 is connected, through piping 20, to the furnace 1 such as to convey into the storage unit 1 7 the hot exhaust gases from the furnace 1. Thus, the tunnel chamber 1 9 of the storage unit 1 7 also functions as a drier to pre-heat and dry the raw tiles prior to their delivery into the furnace 1. For a more detailed description of one possible embodiment of the storage-unit-drier 1 7 useful in the system of this invention, refrence can be had to Italian Patent No. 951790 by the same Applicant.

Of course, along the closed circuit path of the charge-carrying plates in the system according to the invention, more than one storage unit stations as indicated above may be provided.

It will be apparent from the foregoing description how the method and construction and operation of the system according to this invention are implemented and their advantages secured. Thus, thanks to the continuous recycling of the charge-carrying plates, a considerable reduction in charge-carrying plate requirements is afforded, especially while the system is operated at those times of the day when the preparing devices located upstream of the firing furnace and storage devices located downstream thereof are shut off, as well as a considerable reduction in the requirements for storage carriages, wherein tiles only are now stored and no more the chargecarrying plates.

On the other hand, the continuously recycled charge-carrying plates, differently from prior systems which provided for their storage during the cited shutoffs, prevents them from being fully cooled down to room temperature, thus affording energy savings for their successive heating cycle while being passed through the firing furnace 1.

It should be understood that the above description relates to a preferred embodiment of the method and system according to this invention, and that any possible variations which are apparent to the experts in the art fall within the scope of the invention.

As an example, the charge-carrying plate transfer means may comprise, instead of the yoke element described, an arcuate conveyor section having a required curvature and arranged for a vertical translatory movement to connect the various conveyor segments between which the transfer is to take place.

Claims

1. A method for the firing treatment of ceramic articles of manufacture, characterized in that it comprises the steps of feeding into a furnace raw blanks carried on charge-carrying plates, said charge-carrying plates being caused to circulate continuously through a closed circuit path, of passing said chargecarrying plates, as carrying fired articles, through at least one automated article discharging station, and discharging said articles, of feeding said charge-carrying plates to at least one automated loading station to load raw blanks thereon, and of returning said charge-carrying plates through said furnace.

2. A method according to Claim 1, wherein said charge-carrying plates are caused to pass, in their closed circuit path, through a storage unit station adapted for a continued delivery of said charge-carrying plates as carrying said raw blanks to said furnace in the event of shutoffs in said closed circuit.

3. A system for the firing treatment of ceramic materials, comprising a treatment furnace, wherethrough said ceramic materials are transported or carried on a plurality of chargecarrying plates, said system being characterized in that it comprises an apparatus for continuously moving said charge-carrying plates through a closed circuit path also going through said furnace, and means along said closed circuit path for loading and unloading said ceramic materials onto and from said charqe-carrving plates.

4. A system according to Claim 3, characterized in that said apparatus for moving said charge-carrying plates comprises a conveyor including for at least part of its length pairs of conveyor belts arranged laterally spaced apart.

5. A system according to Claim 4, wherein said apparatus for moving said charge-carrying plates further comprises means of transferring said plates between segments of said conveyor arranged at an angle or out of level, said transfer means including a yoke element driven for rotation about a vertical axis and translation along said axis to pick up or deposit on said conveyor segments said charge-carrying plates.

6. A system according to Claim 5, wherein said conveyor segments arranged at an angle or out of level comprise said pairs of conveyor belts arranged laterally spaced apart, and said yoke element is adapted to be intercalated with said pairs of belts in its reciprocating translatory movement.

7. A system according to either Claim 5 or 6, wherein said transfer means comprise also a movable end arm of at least one said conveyor segment cooperating with said yoke element by a relative translatory movement with respect thereto.

8. A system according to any of Claims 3 to 7, wherein said means for loading and unloading said ceramic materials comprise each an article conveyor device, a support member cooperating with said conveyor and adapted to pick up said articles and arrange itself in a coplanar adjoining position with respect to said charge-carrying plates fed on said conveyor, and rack means adapted for transferring said articles from said supporting member to said charge-carrying plates.

9. A system according to Claim 8, wherein said conveyor device comprises a pair of laterally spaced apart conveyor belts, and wherein said supporting member is displaceable under the action of a cam in a vertical direction through the space between said pair of belts to raise said articles on said belts in its upward movement and deposit said articles onto said belts in its downward movement.

10. A system according to any of Claims 3 to 9, characterized in that it further comprises along said closed circuit a storage unit device adapted for continued delivery to said furnace of said charge-carrying plates as carry ing said ceramic articles in the event of shutoffs along said conveyor.

11. A system according to Claim 10, wherein said storage unit device comprises a tunnel chamber provided internally with an auxiliary endless conveyor supporting a plural ity of containers adapted for accommodating therein an amount of said charge-carrying plates as loaded with said ceramic articles and delivering them to the outlet of said tunnel chamber for feeding into said furnace.

1 2. A system according to any of Claims 3 to 11, further comprising along said closed circuit between said loading means and said furnace a drier for pre-heating and drying raw article blanks, said drier being swept by exhaust gases from said furnace through connection piping.

1 3. A system according to Claim 12, wherein said storage unit device also functions as said drier.

14. A method for the firing treatment of ceramic articles of manufacture, as herein claimed, described, and illustrated.

1 5. A system for the firing treatment of ceramic materials, as herein claimed, described, and illustrated.