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(11) | EP 3 358 061 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | OVEN FOR THE TEXTILE SECTOR |
| (57) Disclosed herein is an oven (1) for the textile sector, of substantially parallelepiped
shape and comprising means (5) for ventilation feeding, symmetrically on both sides,
the blowers that ventilate the material with reversible-direction hot air. Said means
(5) for ventilation are provided on the ceiling of the oven (1) itself and the side
walls, which are doors (7) as well of said oven (1), are adapted to be fully opened.
The presence of an air gap, adapted to send and retrieve process air through the material
(11), between the outer side doors (6) and the inner side wall (7) of said oven (1),
is extremely advantageous.
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[0001] The present invention relates to an oven for the textile sector, to be used especially for the production of non-woven fabric.
[0002] The textile sector is one of the oldest industries in the history of technology, with processing based on the weaving of fibres.
[0003] More recently, the so-called non-woven fabric was developed. It is a textile material obtained with procedures different from the classic weaving (which involve a weft and a warp) or knitting methods. In the case of fabrics, the textile fibres are oriented in an orderly arrangement, while in the non-woven fabric, fibres are arranged randomly and statistically.
[0005] Typical features of non-woven fabrics include waterproofness, resistance to low and high temperatures, non-abrasiveness. These features make the non-woven fabrics suitable for several applications, in various technical fields. In the building industry, they can be used to coat or set up ceilings and false ceilings and in the production of the so-called geotextile materials, used for the construction of roads, airports, tunnels, embankments and the like. In the field of home furnishings, they are used for the production of wallpapers, sofas, armchairs, chairs, furniture accessories. In the medical industry, they are used for the production of white coats and other sterile surgical drapes. They are also used for the production of disposable caps and overshoes for swimming pools. There are daily-use objects made of non-woven fabric, such as bags, shopping bags and more. In agriculture, they are used for cloth for the protection of the plants, for the collection and the protection of fruit and vegetables, for the development of seeds, for greenhouse cultivations, to prevent the growth of weeds, to protect the more delicate plants from weather, animals and pests. In clothing, they are used to line shoes and shoulder pads of suits. In manufacturing, they are used for packaging and for the production of filtres. In photography, they may be excellent materials for backdrops. They are also used to improve the grounds for show jumping tracks in horse riding.
[0006] As seen from the above overview - not even complete -, these materials have a wide use and for this reason it is important to produce them under favourable conditions, both economically and industrially.
[0007] As already said, the non-woven fabric can be composed of natural and/or synthetic fibres. Normally, it is produced by means of carding machines. The types of traditional cards are those linked to a web laying machine, or it is possible to use airlays. However, the non-woven fabric produced by these machines is totally devoid of mechanical consistency.
[0008] A common way to confer consistency to these materials is to mix the fibres with low melting fibres which, by melting, bind to other fibres, thus creating a robust and mechanically stable structure. Once the low melting fibres are mixed to the other fibres, they are molten, placing the material in an oven where a hot air flow passes through the material. Among the low-melting-point fibres it is possible to mention, for example, polypropylene and polyester, although there are many other fibres available for this use.
[0009] This hot air flow is created by means of fans and burners, generally placed on the inner face of one of the longitudinal walls of the oven.
[0010] The traditional ovens currently used for these operations are realised as parallelepiped blocks, with feed on the front faces for entrance and exit of a conveyor belt, in order to insert and extract the material before and after the operation. To obtain flow characteristics suitable to confer an even melting of the low-melting-point fibres, the air flow must be periodically reversed during the movement of the material from entrance to exit. For this purpose, gate valves are normally arranged inside the traditional oven, in order to program the direction sequence of the air flow according to the change of the characteristics of the different materials to be treated. The longitudinal sides of these traditional ovens are therefore normally blind, except for small inspection openings, also configured as windows protected by glass. The gate valve assemblies of these traditional ovens have bulky side size (1,5 - 2 m) with respect to the useful width of the oven itself, sometimes causing their installation to be difficult and occupying in an oven with useful width of 2 m an excess of 100% with respect to the space actually needed for the passage of the material. In addition, the air passing treatment of the fibres entails that a part of the fibres comes out of the layer of non-woven fabric in formation and deposits on the oven parts, making it dirty. It is therefore necessary to remove some parts of the oven to extract from it the dirty parts and clean them. For these operations, the inner parts of the oven not being accessible except for the extent allowed by the inspection opening, it is necessary to perform long and difficult cleaning operations. This makes the downtime due to cleaning operations of the parts of the oven relatively long, remarkably affecting productivity.
[0011] Moreover, the side arrangement of the fans makes the even air distribution on the side size of the oven difficult, a problem which is greatly amplified by increasing the working width over 3 m.
[0012] The German utility model No. 203 15 984 discloses a textile machine, in particular an oven for the textile sector, for the continuous treatment of a fabric ribbon. The ventilation of the represented oven, although fans are mounted in the upper part of the oven, conveys the air flows on only one of the two length sides of the oven. Indeed, the opposite side to the ventilation side is provided with shear gates and glass windows, adapted for the observation of the fabric inside the oven.
[0013] The problem underlying the present invention is to propose an oven structure for the textile sector, which overcomes the above mentioned drawbacks and allows to realise the inversion of the ventilation, with the possibility to access the inner part of the oven itself to clean and maintain it, having at the same time a reduced footprint, compared to that of conventional ovens. This object is achieved through an oven for the textile sector, substantially parallelepiped in shape and comprising means for ventilation with hot air, wherein said means for ventilation are provided on the ceiling of the oven itself and the side walls of said oven, being free from valves, fans and burners, are adapted to be fully opened, characterised in that between the outer side doors and the inner side wall of said oven an air gap is present, adapted to send and retrieve process air through the material and in that the valves for the operation of this system are mounted with a minimum fooprint on the same inner doors of the oven. Subclaims describe preferred features of the invention.
[0014] Further features and advantages of the invention will anyhow become more apparent from the following detailed description of a preferred embodiment, given by mere way of nonlimiting example and illustrated in the accompanying drawings, wherein:
Fig. 1 is a sectional side view of an oven according to the present invention, in the closed condition of the doors;
Fig. 2 is a sectional front view of an oven according to the present invention;
Fig. 3 is a side view of an oven according to the present invention, in the manufacturing phase and in the open condition of the doors, but with closed side wall;
Fig. 4 is a side view similar to Fig. 3, after manufacturing completion; and
Fig. 5 is a perspective view of an oven according to the present invention, with open doors and side walls and with several extracted components.
[0015] The oven 1 comprises a workspace 2 including a support conveyor belt 3 and an opposite upper conveyor belt 4. Burners (not shown in the drawings) and fans 5 are provided for the production of hot air, and are arranged on the ceiling of the oven 1, preferably in a central position, to direct the heated air in the various areas of the oven 1.
[0016] Generally, the oven 1 is composed by a series of juxtaposed modules, the number of which is proportional to the productivity in kg/h of non-woven fabric to be obtained, each module having, preferably, a double burner and two fans.
[0018] According to the present invention, the wall 7 is adapted to be fully opened, pivoting on specific hinges (not shown for simplicity), to form two shutters 7A abutting in the centre, which are similar to two shutters of an inner door. Between the outer doors 6 and the wall 7 there is an air gap adapted to send and retrieve process air after it passes through the material.
[0019] Advantageously, the wall 7 has gates 8 on its surface, adapted to perform the inversion of the air flow. Alternatively, fixed openings can be provided, since the double direction of ventilation is not necessary for certain materials. It is important not to confuse the inspection windows described in the German utility model No. 203 15 984 with the inversion gates disclosed in this application.
[0020] Preferably, on the side wall 7 there are channelling elements 9 of the air flow, realised as walls perpendicular to the wall 7: normally, said elements 9 can be rotated as well on specific hinges to allow the opening of the inner walls, without disassembling the panels 9 defining the air ducts.
[0021] The doors 6 also allow, with their closure, to lock in position the channelling elements 9 in the workspace 2.
[0022] The materials are deposited in the form of fibres on the work spare to obtain non-woven fabrics 10.
[0023] Advantageously, the bottom of the oven features ducts for the evacuation of the fumes, while process air is conveyed through independent channels, preferably eight, in pressure and depression.
[0024] In use, the fibres to be used for the formation of non-woven fabric are introduced in the workspace 2 of the oven 1, by mixing the high-melting-point textile fibres, which may be natural fibres, such as cotton, wool, linen; or synthetic fibres, such as rayon, nylon, viscose and others, and low-melting-point fibres, for example (with no limitation thereto) polypropylene or polyesters. The introduction into the oven 1 preferably takes place from the front, where there is a specific entrance with relevant conveyor belts. The material is evenly distributed on the lower support conveyor belt 3. Burners and fans 5 are started. In this way, the hot air is directed on the whole surface of the material resting on the support conveyor belt 3. The air gap between the doors 6 and the wall 7 and the channelling elements 9 serve for this purpose, conveying the air towards the whole workspace 2 of the oven 1 and retrieving it to let the cycle begin again. The burner works keeping the temperature suitable for melting fibres, and the air directed by the fans 5, heated in this way, causes the melting of the low-melting-point fibres. A preferred temperature range is between 80°C and 220°C, depending on the various types of low-melting-point fibres used. Once a type of fibre is chosen, it is advisable to set the suitable temperature, otherwise the melting of the low-melting-point fibres may not occur or may occur only incompletely. Above this temperature, fibre denaturation phenomena could occur.
[0025] The operation continues for the time necessary to completely melt the low-melting-point fibres, suitably adjusting the speed of the oven according to the length of the oven itself. The material in the form of fibres, always via conveyor belt, passes at this point to the next section, similar to the previous ones, but without burners or other heating bodies, for the cooling operation. In this section, the fans 5 continue to direct air, now drawn cold from the outside, which gradually cools down the material, in order to obtain the complete resolidification of the molten material which acts, therefore, as a glue for the other fibres.
[0026] Once almost at room temperature, the material 10 comes out of from the oven 1, ready for the next processing steps.
[0027] The presence of the outer doors 6 and the fact that the wall 7 can be completely opened, also due to their realisation pivoted on hinges, further allow to inspect the workspace 2 of the oven 1, both during downtime and if needed while the oven 1 is working. The opening of the walls 7 on the two sides is such that two operators facing the opened walls 7 are able to see each other without any problem.
[0028] During downtime, it is possible to check the cleanliness level inside the oven 1, taking actions to remove the material that adhered to the surfaces during the melting step. This intervention, as it can be easily understood, generally does not require difficult disassemblies in the oven 1 to access the workspace 2, but requires the opening of the doors 6 and of the wall 7 and the extraction of the parts to be checked through the same opening, with a considerable saving of time and a resulting increase in productivity.
[0029] Furthermore, during the activity of the oven 1, it may be useful to inspect the inside in case of risk of failure and/or fire, so that the present invention achieves a degree of safety which could not be even imagined before.
[0030] Through the same opening which is obtained by the opening of the wall 7, it is also possible to introduce or extract additional diffuser elements, so as to create air blades at a higher pressure and in very narrow areas, while creating a more suitable ventilation for the treatment of different materials.
[0031] In practice, it is the particular construction of the oven which allows to introduce additional elements to obtain different types of ventilation on the non-woven fabric, both at low and high speed, making the machine extremely versatile. Furthermore, replacing the traditional ventilation with the particular gate valves present in the channelling elements 9, allowed the fundamental access to the inner operating part of the symmetrical side ventilation oven, with considerable advantages in terms of cleaning and maintenance.
[0032] Finally, the German utility model No. 203 15 984 exhibits a side ventilation on one side only, while the oven according to the present invention has side and symmetrical ventilation (i.e. on both sides in the length of the oven).
[0033] In short, the present invention allows to obtain a perfectly even melting, due to a symmetric ventilation from the two sides of the oven where there are doors 6 and walls 7, extremely limited plan dimensions of the non-operative ventilation area of the oven (800 mm rather than 2000 mm wide), greater energy efficiency and productivity, the possibility to reverse air flows every 1000 mm length of the oven, the possibility to completely inspect the two sides of the oven, the possibility to extract from both sides all ventilation components for cleaning and maintenance purposes. Furthermore, thanks to the easy replacement of some components of the ventilation circuit, it is possible to use the same oven also for very different processes - for example, both for felts and battings - which is presently not possible. A peculiarity of the present invention is to have an oven for fabrics and non-woven fabrics with ventilation ducts on both sides in the length of the oven and, moreover, with each side provided with power-operated air inversion gates. Without the innovation of the present invention, the inner operating part of the oven, where the fabric passes and which needs frequent cleaning, would be totally inaccessible, because of the obstacle of the air ducts on both sides and of the relevant air inversion gates. This new conception of the oven is now provided with outer and inner side doors, which determine the ventilation ducts of the oven itself.
[0034] The innovation according to the present invention consists in having the air ducts determined by the double doors and the inversion gates integral to the inner doors. In this way, the ventilation sides, totally blind in traditional ovens, make the inner and operating part of the oven, needing frequent cleaning, fully accessible only in the SICAM oven case, with ventilation on both sides and double doors that can be opened.
[0035] Furthermore, ventilation is reversible, thanks to the specific gates mounted directly on the inner doors, which, integral to the doors themselves, allow full access inside the oven.
[0036] Full access is possible despite the presence in the oven of side and symmetrical ventilation ducts (on both length sides) and air inversion gates, which in traditional ovens for non-woven fabrics make the operating part of the oven, where the material to be treated passes, totally inaccessible,.
[0037] It is understood, however, that the invention is not to be considered as limited by the particular arrangement illustrated above, which represents only an exemplary embodiment of the same, but different variants are possible, all within the reach of a person skilled in the art, without departing from the scope of the invention itself, as defined by the following claims.
LIST OF REFERENCE NUMERALS
1. Oven (1) for the textile sector, substantially parallelepiped and comprising means
(5) for ventilation with hot air, wherein said means (5) for ventilation are provided
on the ceiling of the oven (1) itself and the side walls (7) of said oven (1), being
free from valves, fans and burners, are adapted to be fully opened, characterised in that between the outer side doors (6) and the inner side wall (7) of said oven (1) an
air gap is present, adapted to send and retrieve process air through the material
(11) and in that the valves for the operation of the oven (1) are mounted with a minimum footprint
on the same inner walls (7) of the oven (1).
2. Oven (1) as in claim 1), characterised in that the opening of said side walls (7) is pivoted on hinges.
3. Oven (1) as in claim 1) or 2), characterised in that on the side wall (7) or on the outer door (6) there are channelling elements (9)
of the air flow, made as walls perpendicular to the wall (7).
4. Oven (1) as in claim 3), characterised in that said elements (9) can be pivoted, if necessary, on suitable hinges to allow the opening
of the inner walls.
5. Oven (1) as in any one of the preceding claims, characterised in that the wall (7) has gates (8) on its surface, adapted to perform the inversion of the
air flow.
6. Oven (1) as in claim 5), characterised in that these gates can have a counterweighted shear operation.
7. Oven (1) as in any one of claims 1) to 4), characterised in that the wall (7) has fixed openings for the passage of air on its surface.
8. Oven (1) as in any one of the preceding claims, characterised in that there are diffuser elements that can be introduced into or extracted from the workspace
(2) of the oven (1) itself.
9. Oven (1) as in any one of the preceding claims, characterised in that it is composed by a series of juxtaposed modules, the number of which is proportional
to the length of the oven to be obtained.
10. Oven (1) as in claim 9), characterised in that each module has one or more burners and one or more fans.
REFERENCES CITED IN THE DESCRIPTION
This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.
Patent documents cited in the description