EP0965808A1

EP0965808A1 - Device for supporting and driving transfer rollers with a seal in a kiln

Info

Publication number: EP0965808A1
Application number: EP99111093A
Authority: EP
Inventors: Roberto Zavatti
Original assignee: Tecnochimica Sassolese Srl
Current assignee: Tecnochimica Sassolese Srl
Priority date: 1998-06-18
Filing date: 1999-06-17
Publication date: 1999-12-22
Also published as: IT1306298B1; ITBO980378A1

Abstract

A device for supporting and driving the rollers with a seal in a rollerway equipped kiln for heat treatment of various articles includes a first enclosing container (11) for the terminal portions (6a) of the rollers (6), fastened to a lateral external wall (2a) of the kiln.

The first container (11) features one first pair of idle discs (31,32) for supporting each roller. Each roller (6) is driven by a double Cardan joint connected to a small shaft (41), which protrudes from the first container (11) and carries, on its head, a cogwheel (44). The device (10) includes also a second enclosing container (15) fastened to a metallic lateral wall (3a) of the kiln, facing the above mentioned lateral wall (2a). The second enclosing container (15) features tight closed windows (19), which allow an outside inspection during the device operation. The second container (15) features one second pair of idle discs (51,52) for supporting each roller.

Description

The present invention relates to heat treatment of articles for modifying and improving their physical and structural characteristics.
In particular, the present invention relates to a device for supporting and driving rollers in a continuous roller kiln, with a seal around them.
Many articles of common use as well as for particular industrial use must be heat treated, so as to define and/or improve some of their physical and structural characteristics.
For instance, the heat treatment is necessary in production of ceramic articles like tiles, sanitary fixtures, or in production of components of sintered ferrite used in electronics.
Moreover, the heat treatment is used in many other cases.
There are also different types of kilns, in which heat treatment is executed.
One of the most used is a kiln equipped with a rollerway, in which the articles to be treated are introduced into the kiln and conveyed inside the kiln through the heat treatment chamber by a motorised rollerway.
The rollerway includes a plurality of rollers made of ceramic or metallic material, arranged horizontally, perpendicularly to the conveying direction and situated one beside another.
The rollers are driven into simultaneous rotation by driving groups.
Since it is impossible to situate driving groups inside a kiln due to high temperatures reached therein, the driving groups are situated outside the kiln and the ends of the rollers go out through suitable apertures made in the kiln transversal walls, called roller holding slits.
The roller holding slits are usually made in both lateral walls of the kiln.
The rollers are carried by idle supports situated outside the kiln.
The roller holding slits diameters are much bigger than the corresponding rollers diameters, therefore, the roller holding slits set the heat treatment chamber in communication with the outside.
This is a considerable disadvantage of this type of kiln, mainly because there is a continuous heat exchange between the kiln and the outside, which substantially reduces the kiln efficiency.
Moreover, it is impossible to avoid leakage of matter, which includes a part of combustion products and products of sublimation of the raw materials or secondary components of the treated articles.
The emission of such products is highly polluting and detrimental for the kiln operators as well as for other operators working nearby.
That is why security regulations in most countries require severe reduction of the emission of such products, and everywhere there is a tendency to prohibit them definitely.
The roller holding slits are normally closed by suitably shaped plugs of mineral fibre, which do not impede the rollers rotation, but do not manage to prevent sufficiently the communication between the heat treatment chamber and the outside.
Another disadvantage results from the fact that some types of articles (usually particularly valuable), as e.g. components of soft manganese-zinc ferrite used in the electronic industry, must be heat treated in complete absence of oxygen.
In fact, for this purpose, the atmosphere in the heat treatment chamber is changed and devoid of oxygen, which is substituted by nitrogen or other inert gases.
Obviously, the roller holding slits, although closed by the plugs, do not prevent a certain quantity of oxygen from passing inside the kiln, thus making it unsuitable for treatment of the above mentioned articles and therefore, considerably limiting its use field.
Yet further disadvantage derives from the fact that mineral fibres used for closing the roller holding slits are detrimental for the operators, as they are potentially cancerogenic.
Still another drawback lies in the fact that the driving groups provided so far transmit the rotary movement to the rollers in a rather rigid way, often causing displacement of the rollers with respect to their ideal rotation axes and influencing the conveying precision.
The same disadvantages relate to other devices for heat treatment, structurally similar to the above described kilns, such as rollers equipped dryers.
The present invention was evolved with the general object of proposing a device for supporting and driving rollers in a roller kiln, with a seal which avoids the above mentioned disadvantages, guaranteeing best heat insulation of the kiln as well as its perfect tightness with respect to possible emission of toxic substances and possible contamination by substances present outside.
Another object of the present invention is to propose a device as described above, which allows an easy access to the rollers for their inspection or maintenance.
A further object of the present invention is to propose a device, which allows to drive the rollers guaranteeing their constant alignment, independently from the temperature and load conditions.
The above mentioned objects are fully obtained in accordance with the contents of claims.
The features and advantages of the present invention will become fully apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:

Figure 1 is a schematic lateral view of the driving side of the enclosing container, which is a part of the proposed device;
Figure 2 is a schematic section view taken along II-II of Figure 1;
Figure 3 is a view of a part of the idle side of the enclosing container;
Figure 4 is a section taken along IV-IV of Figure 3.

With reference to Figures 1 and 2, the reference numeral 1 generally designates a heat treatment chamber of a rollerway equipped kiln or of a roller dryer.
The kiln, or dryer, only some parts of which are shown for sake of clarity, is indicated by 100.
The heat treatment chamber 1 is obtained according to known techniques and from known materials.
As far as the proposed invention is concerned, the heat treatment chamber 1 features a refractory structure including a first lateral wall 2, equipped with a first plurality of roller holding slits 4, and a second lateral wall 3 (Figure 4), facing the first wall 2 and equipped with a second plurality of roller holding slits 5.
The refractory structure is contained within an external metallic structure, whose corresponding lateral walls 2a and 3a, facing each other, are seen in Figure 1 and Figure 4, respectively.
The heat chamber is equipped with a plurality of transfer rollers 6, arranged side by side, substantially horizontally, perpendicular to a transfer direction of articles to be baked or dried.
The rollers 6 are driven into axial rotation to transfer the above mentioned articles inside the kiln 100.
The terminal portions, namely a driven terminal portion 6a and idle terminal portion 6b, respectively, of each of the rollers 6 extend outside the heat chamber 1 through the corresponding roller holding slits, first 4 and second 5, respectively.
For this purpose, the roller holding slits 4, 5 of each pair are aligned and obviously, the number of the first roller holding slits 4 and the second roller holding slits 5 is equal to the number of rollers 6 in the heat chamber 1.
The proposed device 10 for tight supporting and driving rollers 6 includes a first box-like enclosing container 11, which contains the driven terminal portions 6a of the rollers 6 (see Figure 1).
The first container 11 is fastened to the metallic wall 2a in the region of the first roller holding slits 4.
The first container 11 has also a plurality of through holes 13, substantially coaxial with the rollers 6 and located in its fore surface.
The number of the through holes 13 is equal to the number of rollers 6, and consequently, to the number of the first roller holding slits 4.
A substantially cylindrical hollow cup 7, open at one end to receive the driven terminal portion 6a, is fastened to the head of the driven terminal portion 6a of each roller.
First support means 30 for the driven terminal portions 6a are situated inside the first enclosing container 11.
The first support means 30 include, for each roller 6, a pair of discs 31, 32 (see Figure 2), idle on their axes, arranged side by side directly below the roller 6 and carried rotatably by a support 33 fastened to the base 11b of the first container 11.
The axes of the discs 31, 32 are parallel to the axis of the roller 6.
The discs 31, 32 freely support the driven terminal portion 6a lying thereon.
Actually, according to the illustrated embodiment, the discs 31, 32 support the cup 7 fastened to the driven terminal portion 6a, however, this does not cause particular constructive or functional differences.
The device 10 includes also means 40 for transmitting rotating movement to the rollers 6.
The transmission means 40, situauted substantially coaxial with the rollers 6, are fastened to the rear surface 7a of each cup 7 and extend outwards from the first container 11 through the through holes 13.
In particular, the transmission means 40 include for each roller 6:

a small shaft 41, rotatingly carried by a support 43 fastened to a shelf 43a which in its turn is fastened to the external wall 11a of the first enclosing container 11; the small shaft 41 extends partially outside the enclosing container and partially thereinside;
a cogwheel 44, situated at the external end 41a of the small shaft 41;
uncoupling means 45, including a double Cardan joint, connected in series, fastened at one end to the relative cup 7 and at the other end, to the corresponding small shaft 41; the uncoupling means 45 can release the connection between the rotation axis of the small shaft 41 and cogwheel 44 from the axis of the rollers 6 and considerably reduce the heat transmission outwards from the rollers 6 through the small shaft 41; in fact, due to the use of the double Cardan joint, the contact areas are substantially punctiform, which particularly limits the heat transmission.

Suitable motor means, of known type available on the market, are mechanically connected to the cogwheels 44 in known and not shown way.
Tight seal closing means 14, coaxial with the small shaft 41, are provided in the region of each through hole 13 for sealing the first container 11.
The tight closing means 14 include a ring-like seal made of a suitable heat-resistant material and equipped with a shoulder 14a, also ring-like, which prevents the seal from going out of the relative through hole 13.
In the upper wall 11c of the first enclosing container 11 there is an entrance opening 17 closed by a corresponding removable tight closure door 17a.
The door 17a allows the access to the inside of the first container 11 for inspection and maintenance.
The device 10 includes also a second box-like enclosing container 15 for the idle terminal portions 6b of the rollers 6 (see Figures 3, 4).
The second enclosing container 15 is fastened to the lateral metallic wall 3a, in the region of the second roller holding slits 5.
The second enclosing container 15 is provided with a front opening 18, which allows access to the rollers 6, and with a corresponding removable tight closure door 18a fastened to the second container 15 by a plurality of fasteners 20.
The door 18a gives the access to the inside of the second container 15 for maintenance and substitution of the rollers 6.
A gasket 18b guarantees the tightness of the door 18a.
The door 18a features also a plurality of tight closed windows 19 made of oven glass, situated substantially at the level of the rollers 6 for allowing inspection inside the second container 15.
Second support means 50 for idle terminal portions 6b of the rollers 6 are situated inside the second container 15.
Likewise the above described first support means 30, the second support means include, for each roller, a pair of discs 51, 52, idle on their axes, arranged side by side directly below the corresponding roller 6 and rotatingly carried by a support 53 fastened to the base 15b of the second container 15.
The axes of the discs 51, 52 are parallel to the axis of the roller 6, therefore the idle terminal portions 6b of the rollers 6 lie, freely supported, on the discs 51, 52.
Operation of the device for supporting and driving rollers 6, which is simple and easily understandable, will be now shortly described.
In working conditions, the first enclosing container 11 is completely closed and separated from outside, since the closing door 17a of the opening 17 is installed and the annular seal 14 prevents materials present inside the first container 11 from passing through the holes 13.
It is to be reminded that the inside environment of the first container communicates directly with the heat chamber 11 through the space of the first roller holding slits 4 not occupied by the relative rollers 6.
Likewise, the second enclosing container 15 is completely closed and separated from outside, since the closing door 18a of the opening 18 is mounted and kept tightly closed by the corresponding fasteners 20.
Therefore, the inside environment of the second container 15, which communicates directly with the heat chamber 11, is completely separated from the outer environment, and that is why nothing leaks outside, and no oxygen or other undesired substances enter the heat chamber 1 from outside.
The above mentioned motor means drive the rollers 6 by the respective cups 7, through the cogwheels 44, small shafts 41 and double Cardan joints 45.
The Cardan joints fulfill a very important task of keeping the rotation axis of each roller 6 independent from the axis of the relative group small shaft 41 - cogwheel 44.
This allows the rollers 6 to rotate perfectly about the axis, since this axis is defined only by the position of the first support means 30 and the second support means 50, and therefore to transfer the articles to be treated in best way.
The main advantage of the present invention lies in the fact that the roller kiln or drier, equipped with the proposed tight sealed supporting and driving device, is very heat-tight and prevents materials present in the heat chamber from going outside, while protecting the heat chamber from infiltration of oxygen or other undesired substances entering from outside.
Another advantage of the present invention derives from the fact that the rollers are easily accessible for inspection, maintenance and substitution.
A further advantage of the present invention lies in fact that the device drives the rollers in such a way that they are constantly aligned, independently from the temperature or load conditions.

Claims

Device for supporting and driving rollers with a seal in a rollerway equipped kiln for heat treatment of various articles, said kiln (100) including a heat chamber (1) defined by a first refractory wall (2) having a first plurality of roller holding slits (4) and a second refractory wall (3) , facing the first one, having a second plurality of roller holding slits (5), said heat chamber being also equipped with a plurality of transfer rollers (6), arranged side by side and substantially horizontal, perpendicular to a predetermined transfer direction, said rollers (6) driven into axial rotation and with their terminal driven portion (6a) and terminal idle portion (6b) extending outside of the heat chamber (1) through said first roller holding slits (4) and said second roller holding slits (5), said device characterized in that it includes:

at least one first enclosing container (11) for said driven terminal portions (6a) of the rollers (6), fastened to one lateral external wall (2a) of said kiln (100) in the region of said first roller holding slits (4) and equipped with a plurality of through holes (13), which are substantially co-axial with the rollers and whose number is equal to the number of the rollers (6);

at least one cup (7) for each of said rollers (6), said cup (7) being fastened to the head of the driven terminal portion (6a) of the relative roller (6);

first support means (30) situated inside said first enclosing container (11) for freely supporting said driven terminal portions (6a);

axial means (40) for transmitting a rotation movement to said rollers (6), said transmission means fastened to the cups (7) and extending outwards from the first container (11) through the through holes (13);

tight seal means (14), situated in the through holes (13), coaxial with the axial transmission means;

at least one second enclosing container (15) for said idle terminal portions (6b) of the rollers (6), fastened to one lateral external wall (3a) of said kiln (100) in the region of said second roller holding slits (5);

second support means (50) situated inside said second enclosing container (15) for freely supporting said idle terminal portions (6b).
Device, according to claim 1, characterized in that said first box-like container (11) is provided with at least one access opening (17) and with a corresponding removable tight closing door (17a).
Device, according to claim 1, characterized in that said first support means (30) include, for each roller (6), a pair of discs (31,32), idle on their axes, arranged side by side directly below said roller (6), to freely support the driven terminal portion (6a) of the rollers (6) lying thereon, with the axes of said discs (31,32) parallel to the axis of the roller (6).
Device, according to claim 1, characterized in that said transmission means (40) include, for each roller (6), a small shaft (41) rotatably carried by a support (43) fastened to said first enclosing container (11), and a cogwheel (44), situated on the head of said small shaft (41), externally with respect to said first enclosing container (11).
Device, according to claim 4, characterized in that said transmission means (40) include also uncoupling means (45), situated between said small shaft (41) and cup (7) for uncoupling the rotation axis of said small shaft (41) from the axis of the rollers (6).
Device, according to claim 5, characterized in that said uncoupling means (45) include a double Cardan joint for each roller (6).
Device, according to claim 1, characterized in that said second box-like container (15) is provided with at least one front opening (18) for access to said rollers (6) and with a corresponding removable tight closing door (18a).
Device, according to claim 7, characterized in that said tight closing door (18a) features, made therein, tight windows, situated substantially at the level of the rollers (6) for allowing inspection thereof.
Device, according to claim 1, characterized in that said second support means (50) include, for each roller (6), a pair of discs (51,52), idle on their axes, arranged side by side directly below said roller (6), to freely support the idle terminal portion (6b) of the rollers (6) lying thereon, with the axes of said discs (51,52) parallel to the axis of the roller (6).
Device, according to claim 1, characterized in that said tight closing means (14) include a ring-like seal made of a heat-resistant material.