EP0484812B1 - Apparatus for manufacturing a web with multiple fibres-layers and produced web with this apparatus - Google Patents

Abstract

The present invention relates to an apparatus for manufacturing a web with multiple layers of randomised fibres and to the web obtained with this apparatus, in which a particular number of devices for taking up the fibres from the large drum (11) by means of "mechanical" systems (12, 17, 17', 20, 20', 18, 19, 22, 27, 27', 30, 30', 28, 29), such as the combing cylinders or the like, is combined with a device for taking up the residual fibres (31) from the large drum (11) by means of an air-suction system (21, 23, 25, 26), in such a way that the web or webs produced solely by the mechanical systems (12, 17, 17', 20, 20', 18, 19, 22, 27, 27', 30, 30', 28, 29) and the web produced solely by the air-suction system (21, 23, 25, 26) are formed on different conveyor bands and are subsequently superposed on one conveyor band (24), thus producing an exceptionally uniform web having multiple layers with extremely high randomisation and with the possibility of increasing its weight. <IMAGE>

Description

The invention relates to an apparatus for forming a veil with multiple layers of "randomized" fibers, to be applied to cards equipped with drum cylinders with toothed linings, or card plates or card caps as well as the veil produced by means of this device. Two different types of apparatus for the formation of fiber webs are already known.

With the first type of known apparatus, which we will then call "mechanical", the veil of fibers is formed on the last cylinder - which can be a comber or a condenser - from which it is detached by sampling elements, for example cylinders, combers or the like. One of the drawbacks presented by devices of this type is that they make it possible to obtain a veil whose maximum weight cannot exceed 20 to 30 g / m at each sampling point.

The fibers of these sails are combed by the combing cylinders in the direction of advancement of the strip and then picked up by the condensing cylinders. Although during the collection the condensing cylinders aim to disorient the fibers, its orientation always remains, in a very large percentage, in the direction of the advancement of the strip, and for that they appear substantially aligned in the direction of the warp .

This is why these sails are uniform, but they have little resistance in the weft direction and a lot of resistance in the warp direction.

Another drawback relating to devices of this type is that they do not allow the fibers of the large drum to be completely detached. Indeed, the large drum itself tends to entrain back 10 to 20% of the fibers. This fact has a negative influence on the performance of the machine since it decreases its productivity.

An example of a "mechanical" device is described in GB patent A 338,155 which provides several cylinders and combing devices. But in fact, despite this, residual fibers still remain on the main cylinders, which reduce productivity.

In said patent the two layers are obtained by the same "mechanical" system. The successive superposition of the two layers, which always have the same characteristics and the same defects, only serves to reduce the irregularities in product thickness, when said irregularities are derived from feed faults. In addition, this patent does not use the more refined fibers, which always remain attached to the large cylinder, and it cannot produce sails of considerable weight.

A second type of apparatus is known, with which the veil is formed by removing the fibers from a distributor, normally constituted by a large cylinder or large drum by an air suction system which deposits the fibers on a strip. conveyor, or on a perforated net, positioned below the appliance. Examples of this type of apparatus are described in US Patent No. 4097965 of 4/7/78 in the name of Scott Paper Co and in EPO Application No. 83302408.6 of 28/4/83 in the name of Chicopee.

The sails, obtained by the air suction system have the quality of having the fibers oriented in all directions, according to 360 ° C; there follows a uniform resistance of the veil in all directions. The sails obtained by the air suction system also have the possibility of reaching much larger weights than the "mechanical" ones.

But, with the formation of a single veil, all the irregularities coming from the drum where the fibers have a different cohesion, are transmitted to the product which is therefore not uniform, but uneven and collected irregularly. In accordance with the known technique, modifications or improvements have been made to improve the quality of the veil, but for example the two inventions in the name of Curlator Corporation described in US Pat. No. 2,890,497 of 6/16/59 and No. 3,768,119 of 10/30/73 and that of Italian patent N ° 1157863 of 2/19/82 in the name of Governale Marco, only allow to reach very limited working speeds, this to avoid compromising the quality of the veil in this which relates to the first two patents cited and, in the case of the third, because otherwise, the fibers are detach from the stripper cylinder before reaching the unloading area.

The object of the present invention is to increase the productivity of the machine by obtaining a haze, even of considerable weight, while nevertheless having a uniform and compact product.

To achieve this objective, we have produced an apparatus which comprises a number of devices for removing fibers from the large drum by means of "mechanical" systems, such as cylinders, combing machines or the like, combined with a device used for removing from the large drum the residual fibers by an air suction system, so that the veil (s) produced exclusively by "mechanical" means and the veil produced exclusively by means of the air suction can be superimposed on a conveyor belt, creating a veil with multiple layers, characterized by an exceptional uniformity and a very high randomization.

Thanks to this device, the advantages of both systems are obtained, eliminating their disadvantages, that is to say that the weight of the web can be increased, independently of the speed of the machine as well as its productivity, by providing a excellent quality product.

In fact, the device which is the subject of the present invention, which combines the two known systems for removing fibers - "mechanical" and by air suction system - makes it possible to produce sails with a wide variety of weights. Indeed, while the mechanical sampling system does not make it possible to obtain sails weighing more than 30 g / m per sampling point, the sampling system by air suction, which collects all the residual fibers of the drum, imposes no limitation and allows the production of sails whose weight can reach up to 200 g / m, regardless of the speed of the machine.

In addition, by using the apparatus which is the subject of the present invention, the quality of the product is better, since the residual fibers, which the cleaning cylinders do not succeed in detaching, are the most refined and they are distributed over the drum more evenly, since they are inside the linings of the drum. These fibers are not drawn back by the drum but they are collected by the air suction system and they form a complementary veil whose quality characteristics are excellent, which is added to the other veils condensed by means " mechanical ". The veil thus obtained is clearly more compact, more regular; the fibers are more randomized and there is the possibility of increasing the weight of the veil.

Finally, the productivity of the machine can be increased because the subsequent removal of the residual fibers from the drum leaves sufficient space for a larger quantity of feed fibers.

• la fig. 1 représente en projection verticale le schéma d'un exemple de réalisation d'un appareil selon la présente invention.
• la fig. 2 est l'agrandissement d'un détail de la fig. 1;
• la fig. 3 représente en projection verticale un autre schéma de réalisation d'un appareil selon la présente invention.

Other characteristics and advantages of the invention will be highlighted by the following description of some preferred embodiments, represented by the figures which are annexed only by way of illustration and without limitation where:

• fig. 1 shows in vertical projection the diagram of an embodiment of an apparatus according to the present invention.
• fig. 2 is the enlargement of a detail of FIG. 1;
• fig. 3 shows in vertical projection another diagram of an apparatus according to the present invention.

In these figures, similar elements are indicated with the same numerical symbols.

In figure 1, the number (10) indicates a card known for the formation of fiber veils.

The outer surface of the large drum (11) is equipped with a toothed lining (13) illustrated in FIG. 2. A painter cylinder (12) rotates in the opposite direction to that of the large drum (11), and its toothed lining takes off part of the fibers, fed by the large drum (11). The fiber mat which forms is then condensed by the condensing cylinders (17) and (17 '), from where it is removed by means of sampling cylinders (20) and (20'), which deposit it on a strip. conveyor (18). According to the known technique, by adjusting the speed differences between the cylinders and the drum, it will be possible to obtain a weight of the product different from that which is loaded, normally variable but whose final weight of the veil does not exceed approximately 30 g / m so as not to compromise the quality of the veil.

The same thing happens with the following analogous cylinders (22, 27, 27 ', 30, 30') and the conveyor belt (28). The painter cylinder (22) also rotates in the opposite direction of rotation to that of the large drum (11) and by means of its toothed lining (14), indicated in FIG. 2, it takes a later part (16) of the fibers. (15) remained on the large drum (11). The fiber mat which forms is then condensed by the condensing cylinders (27) and (27 '), from where it is taken up by sampling cylinders (30) and (30'), which deposit it on a conveyor belt. (28). On the part (29) of the strip (28), the layer of fibers originating from the part (19) of the strip (18) is also deposited, thus forming a double layer of fibers.

However, it is known that a large amount (10 to 20%) of residual fibers (31) still remains inside the teeth of the lining (13), and these are precisely the most refined, carded and flexible, which are distributed with the greatest uniformity over the entire width of the large drum (11). In known cards, the return of this percentage inevitably constitutes a reduction in machine productivity, but it is impossible to remove these residual fibers mechanically. since they are very inside the toothed lining. The possibility of recovering these residual fibers by another means therefore represents an essential characteristic of the present invention. This object is achieved by placing below the large drum (11), after the combing cylinders (12), (22), a vacuum chamber (21), and below the latter a suction system for air (23). The position of the vacuum chamber (21) relative to the large drum (11) is such that the residual fibers (31) are sucked in and come off the drum. Through the vacuum chamber (21), the residual fibers (31) remaining from the previous operations are removed and the large drum (11) remains clean. The suction system (23) sucks the air through a net or a perforated conveyor belt (24) where the residual fibers (31) are deposited, there they are conveyed by the walls (25) and (26) and by the side walls of the vacuum chamber (21) quine are not illustrated in the drawings. On the web thus formed on the strip (24), are superimposed those which come from the strip parts (19) and (29), forming three layers of fibers which are then consolidated together by known means. FIG. 3 illustrates one of the possible variants of the present invention, with three groups of cylinders (12, 17, 17 ', 20, 20'; 22, 27, 27 ', 30, 30'; 32, 37, 37 ', 40, 40 '); and four conveyor belts (18, 19; 28, 29; 38, 39; 24). The part of fibers which is not removed from the large drum (11) by the combing cylinder (12) for the formation of the first layer of veil, meets the combing cylinder (22) for the second layer of formation of the veil, as described by the example in FIG. 2. In the case illustrated by FIG. 3, the portion of fibers remaining on the large drum (11) meets the third comb cylinder (32) for the third formation of the web. Finally, after the last combing cylinder (32), the air suction system (23) takes from the internal part of the toothed lining (13) of the large drum (11) the residual fibers (31), which are better carded, leaving the large drum (11) completely clean. The number of combing cylinders (12, 22, 32) and the relative condensing cylinders (17, 17 ', 27, 27', 37, 37 ') will be established on the basis of the characteristics of the fibers supplied and of the desired product.

The present invention makes it possible to obtain a uniform and regular veil, not only by virtue of the different quality of the veils of different formation, but also because the defects likely to derive from unequal excess of fibers in the feed are distributed over paths. of different nature and length, which is why any insufficient supply will be subdivided into different sails, the thinnest areas of which will never correspond and will never overlap on the perforated conveyor belt (24). We therefore obtain an effect similar to that of a varnish with "several layers" which, as we know, is more uniform with a smaller total amount of product only one thicker layer.

The examples illustrated represent the "mechanical" system for removing and forming the web by means of condensing and taking cylinders, but it is clear that the invention encompasses any other system for removing and forming the web by "mechanical" systems such as , for example the use of stripping cylinders, combing machines to detach the veil or other similar systems, acting either directly on the painting cylinder, or on the following condensing cylinders. Any additional vacuum chambers or any modification and variant of details which may seem elementary to a technician in the sector, are included in the scope of protection of the present invention, as well as the product obtained with the present device.

Claims (2)

1. Apparatus for manufacturing a web with multiple randomized fiber-layers characterized in that it consists of an assembly of devices that remove the fibers from the main drum (11) by means of "mechanisms" (12, 17, 17', 20, 20', 18, 19, 22, 27, 27', 30, 30', 28, 29) such as cylinders, combers, or the like, and fitted with an a device (31) to remove residual fibers from the drum (11) by means of an air suction system (21, 23, 25, 26) and in that the web(s) exclusively produced with mechanical systems and the web exclusively produced with the air suction system are superimposed on a conveyor belt (24) and in that the "mechanism" consists of one or more combing cylinders (12, 22) rotating in opposite direction to the main drum (11), while its saw tooth card clothing (14) removes part of the fibers (16) fed by the main drum (11) are then condensed by the condenser or compression rollers (17, 17', 27, 27') from where this portion of the fibers is removed by the drawing cylinders (20, 20', 30, 30') and deposited as a web on a conveyor belt (18, 19, 28, 29), while a vacuum chamber (21) located directly below the main drum (11) behind the combing cylinders (12, 22), and a suction fan (23) being placed below the vacuum chamber will remove the residual fibers (31) from the main drum (11) by suction and deposit them in the form of a web on the conveyor belt (24); this web will be topped by other webs coming from other conveyor belts (19, 29) thus forming a multiple layer fiber web .
2. Web with multiple randomized fiber layers characterized in that this web is uniform and compact since it consists of several superimposed webs obtained by combining various devices removing the fibers from the main drum (11) and in particular by using "mechanical" systems (12, 17, 17', 20, 20', 18, 19, 22, 27, 27', 30, 30', 28, 29) as well as an air suction system (21, 23,,25, 26) as described in claim 1, and because the fibers of the webs obtained by "mechanical" removal of the fibers are perfectly uniform and resistent in weft direction, joining their characteristics to those of the webs obtained hy using the air suction system (21, 23, 25, 26), which webs are more refined and random oriented resulting in a much more compact, much more uniform and resistant web according to a 360° angle so that they have a smoother surface and may reach a considerable weight.

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