Card including an accumulator transfer cylinder, and a method of producing a non-woven web

Abstract

The card has an accumulator transfer cylinder between the carding drum and the first cylinder for forming a non-woven web. In order to take up fibers from the periphery of the carding drum, the accumulator transfer cylinder preferably has clothing comprising a plurality of teeth that are inclined relative to the radius of the accumulator transfer cylinder and oriented in the direction of rotation of said cylinder. When the card is in operation, the accumulator transfer cylinder is driven in the opposite direction of rotation to the direction of rotation of the carding drum and at a circumferential speed greater than the circumferential speed of the carding drum.

Description

[0001] The present invention relates to the textile field, and more particularly to the field of producing non-woven webs by means of a card. The invention mainly provides a novel card having an improved outlet, and a novel method of producing a carded non-woven web. The preferred but non-exclusive application of the invention lies in production at high speed (typical production speeds greater than or equal to 150 meters per minute (m/min)) of carded non-woven webs made up of fibers of the polypropylene, polyethylene, cotton, viscose, etc. types.

[0002] A card for producing a non-woven web essentially comprises at least one rotary carding drum, referred to as a main drum or a big drum, with carding members mounted at the periphery thereof. In operation, fibers transported at the periphery of the carding drum are individualized (i.e. the fibers are carded) by the combined actions of the carding members and of the peripheral covering or “clothing” on the carding drum. Generally, and by way of non-limiting example, the carding members are made up of one or more successive carding groups, each carding group being made up of a “working” roller associated with a “stripper” or “wiper” roller. In another embodiment, those carding members can be stationary and in the form of a stationary casing (also referred to as a “carding sheet”) comprising a plurality of stationary carding points at the periphery of the carding drum.

[0003] Normally, while a conventional carding structure is in operation, each time the carding drum rotates some greater or smaller fraction of the fibers at the periphery of the carding drum are taken up at a point situated downstream from the carding members, while the residual fraction of the fibers at the periphery of the carding drum are recycled by the carding drum back towards the carding members. Fibers are taken up from the periphery of the carding drum by one or more successive cylinders that form a card outlet, and that generally work the fibers, having the function of forming a non-woven web out of said fibers on the periphery of said cylinders. In the text below, these cylinders are generally referred to as cylinders for forming a non-woven web.

[0004] At present, several card outlet configurations are known that implement a plurality of successive cylinders for forming a non-woven web. The four most widespread card outlet configurations are given below as non-exhaustive examples.

[0005] A first known card outlet configuration enabling a parallel non-woven web to be produced uses one or more successive combing cylinders as cylinders for forming a non-woven web.

[0006] A second known card outlet configuration enabling a tangled non-woven web to be produced uses a cylinder referred to as a “drum-backing cylinder” followed by a combing cylinder as cylinders for forming the non-woven web.

[0007] A third known card outlet configuration enabling a condensed non-woven web to be produced uses a combing cylinder followed by at least one condensing cylinder as its cylinders for forming the non-woven web; usually the combing cylinder is followed by two successive condensing cylinders.

[0008] A fourth known card outlet configuration implements a drum-backing cylinder followed by a combing cylinder and a condensing cylinder as cylinders for forming the non-woven web.

[0009] In the above-mentioned conventional card configurations, the carding drum acts both in its function of individualizing fibers (carding fibers by the carding members in co-operation with the carding drum), and in forming the non-woven web at the outlet from the card by means of the cylinders for forming the non-woven web working on the individualized fibers that are transported at the periphery of the carding drum. As a result, the speed of rotation of the carding drum is an adjustment parameter which determines very largely both the quality with which fibers are carded at the periphery of the carding drum by the carding members, and the mechanical properties of the non-woven web that is produced (isotropy, weight per unit area, . . . ).

[0010] The speed of rotation of the carding drum must therefore be adjusted so as to comply with two distinct constraints (firstly carding quality, and secondly obtaining the required mechanical properties for the non-woven web that is produced), thus requiring the designer of the card to select a compromise in this adjustment.

[0011] In practice, obtaining the required quality of fiber carding requires the speed of rotation of the carding drum to be adjusted within a relatively narrow range of speeds, and it is starting from this adjustment range of the carding drum that the designer of the card deduces adjustments for the speeds of the web-forming cylinders so as to obtain a non-woven web presenting the required mechanical properties (weight per unit area, isotropy, . . . ).

[0012] Given that the range of speeds within which the carding drum can be adjusted is narrow because of the fiber carding function which must be performed by said drum, the designer of the card is, in practice, restricted in the speeds of rotation that can be selected for the cylinders that form the non-woven web, and consequently in adjusting the production speed of non-woven web output by the card. In addition, it is difficult to increase the production speeds of non-woven web output by the card without harmfully damaging the mechanical properties of the web.

[0013] The present invention seeks to propose a novel card structure which mitigates the above-specified drawback in that it provides greater flexibility in adjustment of the speeds of the cylinders for forming the non-woven web. Another object of the invention is to be able to increase the production speed of the card without damaging the mechanical properties of the non-woven web produced.

[0014] The card of the invention is conventional insofar as it comprises a card comprising a carding drum, carding members mounted at the periphery of the carding drum, and at least one card outlet having at least a first cylinder for forming a non-woven web.

[0015] According to a first characteristic of the invention, the card comprises an accumulator transfer cylinder between the carding drum and the first cylinder for forming a non-woven web.

[0016] The function of the accumulator transfer cylinder of the card of the invention is merely to take up the fibers transported at the periphery of the carding drum without working them while they are being transferred from the carding drum, and to feed the first web-forming cylinder with fibers, thereby forming a buffer accumulator between the carding drum and the first web-forming cylinder, given that fibers are free to be recycled at the periphery of the transfer cylinder.

[0017] The fiber pickup function that is to be performed by the accumulator transfer cylinder is not very constraining in terms of adjusting the speed of rotation of said cylinder, and it can advantageously be ensured by adjusting the speed of rotation of the accumulator transfer cylinder over a range of speeds that is very broad. In practice, it suffices for the speed of rotation of the transfer cylinder to be adjusted in such a manner that its circumferential speed is faster than the circumferential speed of the carding drum. It thus becomes easy to adjust the speed of rotation of the transfer cylinder within this very wide range so as to optimize fiber feed to the first cylinder for forming the non-woven web, and as a result this feed is adapted to the desired production characteristics (speed of production, mechanical properties required for the non-woven web (weight per unit area, isotropy, . . . )). Thus, compared with the above-mentioned traditional solutions, the accumulator transfer cylinder makes it possible advantageously to obtain better decoupling between the carding function (individualizing fibers by carding between the carding drum and the carding members of the card) and the function of forming the non-woven web which is performed by the cylinder or successive cylinders downstream from the accumulator transfer cylinder.

[0018] The present invention also provides a method of producing a non-woven web by means of the card of the invention. In this method, on each revolution of the carding drum, the accumulator transfer cylinder is used to take up more than 90%, and preferably to take up 100% of the fibers transported on the periphery of the carding drum.

[0019] Other characteristics and advantages of the invention appear more clearly on reading the following description of a preferred embodiment of a card of the invention, which description is given by way of non-limiting example and with reference to the accompanying drawings, in which:

[0020] FIG. 1 is a diagram of a line for producing non-woven web by implementing a dual-outlet card of the invention;

[0021] FIGS. 2 and 3 are detail views of an example of teeth on the clothing of the accumulator transfer cylinder of the FIG. 1 card; and

[0022] FIG. 4 is an enlarged view of the transfer zone between the carding drum and the accumulator transfer cylinder of the FIG. 1 card.

[0023] The production line shown in FIG. 1 serves to manufacture in parallel two non-woven webs W1 and W2 which are deposited on and transported by two transport belts B. At a subsequent stage in manufacture, these two non-woven webs W1 and W2 are consolidated separately by any known consolidation means, or for example they can be superposed so as to form a thicker non-woven web which is subsequently consolidated.

[0024] The FIG. 1 production line comprises a conventional loader and weighing machine 1 which feeds a dual-outlet card 3 via a conveyer 2.

[0025] The card 3 comprises a traditional card inlet constituted by a trough 3a, a feed roller 3b, and a taker-in cylinder 3c. The taker-in cylinder 3c feeds a first rotary carding cylinder 3d referred to as a breast cylinder, having its surface covered in conventional manner with card clothing or any other equivalent means enabling it to pick up fibers from the periphery of the taker-in cylinder 3c. In conventional manner, the breast cylinder 3d is also provided on its periphery with a plurality of carding members which serve to work the fibers that have been caught in the card clothing of the cylinder 3d, so as to individualize them. In the particular example shown, these carding members are constituted by a plurality of successive pairs, each comprising a wiper roller 3e and a working roller 3f. Downstream from these carding members, the fibers are taken up from the periphery of the first carding cylinder 3d and transferred without change to a second rotary carding cylinder 3h by means of a transfer cylinder 3g, referred to as a “communicator”.

[0026] The second carding cylinder 3h, also referred to as the “big drum” or “main drum” is referred to below in the present description as the “carding drum”. This carding drum 3h is conventionally covered on its periphery in card clothing enabling it to take up fibers from the periphery of the communicator 3g. The carding drum 3h is also fitted around its periphery with carding members 3e, 3f identical to those fitted to the first carding cylinder 3d.

[0027] The invention is not limited to a card having the particular card configuration 3 with two carding cylinders as shown in FIG. 1. In particular, depending on the type of fibers that are to be opened, and on the degree of opening that is desired for said fibers, it is possible to envisage using a card that is longer, e.g. implementing at least three successive carding cylinders, or on the contrary a card that is shorter, implementing a single carding cylinder. Furthermore, the rollers 3e and 3f could be disposed so as to be juxtaposed in alternation one after another in a configuration that is referred to by the name “Garnett”. The wiper and working rollers 3e and 3f at the periphery of each carding cylinder could also be replaced by any different structure that performs the same function, i.e. having the function in co-operation with the carding cylinder of individualizing the fibers on the periphery of the carding cylinder. In particular, these rollers could be replaced by static plates, referred to as “carding sheets” mounted at the periphery of the carding cylinder and carrying a plurality of stationary carding points, e.g. in the form of grooves or fluting.

[0028] The card 3 of FIG. 1 has two outlets, respectively an upper outlet and a lower outlet, each outlet conventionally comprising web-forming cylinders 3j and 3k. In the preferred embodiment shown, the first web-forming cylinder 3j is a combing cylinder. The second web-forming cylinder 3k is a condensing cylinder. These two cylinders operate in conventional manner to form a condensed non-woven web out of fibers which are brought to the periphery of the combing cylinder 3j. Each non-woven web (W1, W2) is detached from the periphery of the condensing cylinder 3k by a detaching device of the kind described in European patent application EP-A0 704 561. The detaching device essentially comprises a detaching cylinder 31 which enables the fiber to be detached from the periphery of the condensing cylinder 3k and enables it to be deposited on the transporter belt B. The transporter belt is permeable to air and a suction box S is provided in the detachment zone so as to suck the non-woven web against the surface of the transporter belt B. In FIG. 1, the additional element 3m is a rotary brush.

[0029] In a conventional card configuration, the first cylinder for forming a non-woven web, such as the combing cylinder 3j, is mounted directly at the periphery of the carding drum 3h. That disposition makes adjusting the speed of the carding drum 3h and of the web-forming cylinders difficult and constrained. The speed of rotation of the carding drum 3h needs to be adjusted so as to make it possible simultaneously to perform carding effectively with the carding members 3e and 3f, and also to comb the fibers effectively while they are being transferred between the drum 3h and the first web-forming cylinder 3j.

[0030] Also, when the combing cylinder 3j is juxtaposed to the carding drum 3h, in order to use a detacher device of the type shown in FIG. 1 with a detaching cylinder 31 and a transporter belt B, it was necessary in the past, in practice, to use two condensing cylinders 3k in succession instead of a single cylinder as in the configuration of the invention. Using two successive condensing cylinders presents the drawback of causing the non-woven web to be rolled between the two condensing cylinders, where such rolling is a harmful source of condenser clogging and bubble phenomena.

[0031] With reference to FIG. 1, and in accordance with the invention, the first web-forming cylinder 3j is no longer placed at the periphery of the carding drum 3h, but the card 3 has an accumulator transfer cylinder 3i between the carding drum 3h and both of the first cylinders 3j for forming a non-woven web. In the embodiment shown, the accumulator transfer cylinder 3i is adjacent to each of the first web-forming cylinders 3j of each of the two outlets.

[0032] In general terms, the function of the accumulator transfer cylinder 3i is to take fibers from the periphery of the carding drum 3h and to transfer them unchanged, without subjecting them to any particular working, as opposed to the fiber reorientation that is performed, for example, by a web-forming cylinder such as a combing cylinder 3j or a condensing cylinder 3k. The transfer cylinder 3i thus acts firstly as a simple communicator with respect to the carding drum 3h, and secondly performs a function of distributing the fibers and of regulating the rate at which the fibers are fed to each of the first web-forming cylinders 3j.

[0033] In order to perform the functions, the accumulator transfer cylinder 3i is fitted on its periphery with metal clothing G, with a particular, embodiment thereof being shown in FIGS. 2 and 3. The clothing G comprises a plurality of teeth 4. In FIG. 2, double-headed arrow L represents the direction parallel to the longitudinal axis of the accumulator transfer cylinder 3i, i.e. the direction orthogonal to the plane of FIG. 1. FIG. 3 is a section view through the clothing on the accumulator transfer cylinder 3i on a plane extending transversely to the longitudinal axis of the accumulator transfer cylinder 3i. With reference to FIG. 2, the teeth 4 of the clothing G are aligned in the form of adjacent rows parallel to the longitudinal axis of the accumulator transfer cylinder 3i; in FIG. 2, only two adjacent rows of teeth 4 are shown. With reference to FIG. 3, each tooth 4 of the clothing G slopes relative to the radius of the accumulator transfer cylinder 3i at an angle A which points in the direction of rotation of said cylinder (circumferential speed V2).

[0034] In FIG. 4, the teeth 4 of the clothing G on the transfer cylinder are shown highly diagrammatically mainly for the purpose of showing their inclination and orientation as described above. FIG. 4 also shows the carding drum 3h being fitted in conventional manner with card clothing G′ of the usual kind, having teeth 4′ inclined relative to the radius of the carding drum 3h and oriented in the direction of rotation of the carding drum 3h.

[0035] With reference to FIGS. 1 and 4, when the card 3 is in operation, the accumulator transfer cylinder 3i is rotated in the opposite direction to the card drum 3h. More particularly, the speed of rotation of the accumulator transfer cylinder 3i is adjusted in such a manner that its circumferential speed V2 (FIG. 4) is greater than the circumferential speed V1 of the carding drum 3h. In operation of the card, the fibers which are being transported at the periphery of the carding drum 3h, after being individualized by the action of the carding members 3e and 3f are taken up into the clothing G of the accumulator transfer cylinder 3i. On being transferred from the carding drum 3h to the accumulator transfer cylinder 3i, each fiber is taken up by the teeth 4 of the clothing G on the transfer cylinder 3i without being retained by the teeth 4′ of the clothing G′ on the carding drum 3h. As a result the fibers are transferred unaltered, without being worked, unlike that which occurs in a conventional card structure when the fibers are taken from the periphery of the carding drum by a web-forming cylinder of the combing cylinder or drum-backing cylinder type.

[0036] According to another characteristic of the invention, on each revolution of the transfer drum 3h, the accumulator transfer cylinder 3i is caused to take up as many as possible (at least 90%) of the fibers being transported by the carding drum, and preferably 100% of these fibers. For this purpose, the circumferential speed V2 of the accumulator transfer cylinder 3i relative to the circumferential speed V1 of the carding drum 3h is appropriately adjusted. To this end, and in practice, it is preferable for the speed ratio (V2/V1) to be greater than or equal to 1.2, and preferably greater than or equal to 1.3.

[0037] Thus, contrary to that which is conventionally attempted in a conventional card, fibers are no longer recycled around the periphery of the carding drum 3h, with all or nearly all of the carded fibers being taken up by the accumulator transfer cylinder 3i.

[0038] In the past, there has been a prejudice to the view that it is preferable, if not essential, for fibers to be recycled on the periphery of the carding drum 3h. It was believed that it was advantageous for each fiber to be carded several times over by this recycling. However, the Applicant has discovered firstly that on a conventional card, the fibers which are recycled in practice are fibers which are held captive in the carding drum clothing, while fibers situated on the outer periphery of said clothing tend for the most part to be taken up directly by the web-forming cylinders after passing between the carding members only once. This phenomenon becomes increasingly preponderant with increasing working speed of the card. In other words, once the clothing of the carding drum 3h has become filled with fibers, new fibers introduced at the inlet of the carding drum are not recycled by the drum and they leave the carding drum directly after passing once only between the carding members. Consequently, the Applicant has discovered that recycling is, in practice, unnecessary.

[0039] Secondly, in the card of the invention, the absence of fiber recycling on the periphery of the carding drum 3h makes it possible advantageously to avoid filling the card clothing of the carding drum 3h. Thus the new fibers presented on the inlet of the carding drum 3h by the communicator cylinder 3g are taken up by clothing that is empty, instead of clothing that is full as is the case in the conventional solution. The teeth of the carding clothing on the drum 3h thus enable a better carding effect to be obtained in co-operation with the peripheral carding members 3f and 3e, thereby ensuring that the fibers transported at the periphery of the drum 3h are carded better.

[0040] According to another advantage of the invention, the speed of rotation of the carding drum 3h can be adjusted in a manner that is practically independent of the speeds of rotation of the web-forming cylinders 3j and 3k. In the invention, the speed of rotation of the carding drum 3h is adjusted solely on the basis of the quality with which fibers are carded between said drum and the carding members 3f and 3e. Once the speed of rotation of the carding drum 3h has been adjusted, the speed of rotation of the accumulator transfer cylinder 3i is adjusted so as to satisfy the above-mentioned speed criterion which is not very restricting (circumferential speed V2 of the accumulator transfer cylinder 3i should be greater than the circumferential speed V1 of the carding drum 3h). The respective speeds of rotation of the web-forming cylinders 3j and 3k are adjusted so as to obtain the desired work on the fibers. In practice, the speed of rotation of the combing cylinder 3j is adjusted so that its circumferential speed is less than the circumferential speed of accumulator transfer cylinder 3i. The circumferential speed of the combing cylinder 3j is preferably less than or equal to 25% of the circumferential speed of the accumulator transfer cylinder 3i. The speed of rotation of the condenser cylinder 3k is selected so that its circumferential speed is less than about 80% of the circumferential speed of the combing cylinder 3j.

[0041] In operation, the fibers taken up at the periphery of the accumulator transfer cylinder 3i are transported by said cylinder to the two combing cylinders 3j. Each combing cylinder 3j picks up a fraction of these fibers, and the remaining fibers are recycled at the periphery of the accumulator transfer cylinder 3i. In order to prevent the fibers transported at the periphery of the accumulator transfer cylinder 3i flying away, this cylinder is preferably fitted around its periphery with casing members C1, C2, and C3 (FIG. 1).

[0042] According to an additional characteristic of the invention, the card 3 has one or more carding members mounted at the periphery of the accumulator transfer cylinder 3i. For example, with reference to FIG. 1, the casing member C1 can be replaced by one or more carding sheets which, while the card is in operation, serve to work the fibers that are being transported at the periphery of the accumulator transfer cylinder 3i. This serves to obtain additional untangling of these fibers thus making it possible advantageously to obtain a non-woven web of better quality at the outlet from the card, and in particular a non-woven web of more regular quality. In another variant, the carding sheets could be replaced by any other card member performing the same functions, for example by one or more pairs of working and wiping rollers. These additional carding members are preferably positioned in a region situated upstream from the fiber transfer zone (for a card having a single outlet) or upstream from the fiber transfer zones (for a card having a plurality of outlets) between the accumulator transfer cylinder 3i and each of the first cylinders 3j for forming a non-woven web. In the particular example of FIG. 1, this preferred region for positioning the carding members corresponds to the peripheral zone of the accumulator transfer cylinder 3i which is occupied by the casing member C1, i.e. which extends between the carding drum 3h and the lower combing cylinder 3j.

[0043] With reference to FIG. 1, it can be seen that the diameter d of the transfer cylinder 3i is less than the diameter D of the carding drum 3h. In the card of the invention, this leads to an advantageous result whereby the fibers which are recycled at the periphery of the accumulator transfer cylinder 3i are presented more frequently to the two combing cylinders 3j. Thus, if a periodic fault should exist on the accumulator transfer cylinder, this recycling of fibers at a higher frequency ensures that the periodic faults that are generated in the resulting non-woven web are more difficult to perceive.

[0044] According to another advantage of the invention, in the preferred configuration shown in FIG. 1, each combing cylinder 3j advantageously collects fibers from above, thus allowing gravity to act in the right direction on the combing cylinders. In addition, it is advantageously possible to make use of a single condenser cylinder 3k after each combing cylinder 3j, the non-woven web formed at the periphery of the condenser cylinder being presented to be detached by the detacher cylinder 31 and thus being deposited on the transporter belt B.

[0045] In the light of the above description of the card 3, it will be understood that the transfer cylinder 3i of the invention serves advantageously to achieve better decoupling between firstly, the carding function of the card and secondly, the function of forming a non-woven web, and thus achieves better independence in adjusting the speeds of the elements that perform these two functions. The speed of rotation of the carding drum 3h is adjusted in such a manner as to optimize the operation of carding the fibers as performed by the carding members 3e and 3f; the speed of rotation of the accumulator transfer cylinder 3i is set so as to adjust the rate which fibers are fed to the inlet of each of the first web-forming cylinders, and also so as to obtain the production speed required for each web delivered by the card, while nevertheless being adjusted to a speed which is sufficient to ensure that the accumulator transfer cylinder can take fibers from the periphery of the carding drum; the speeds of rotation of the web-forming cylinders are adjusted so as to optimize the work performed on the fiber by the cylinders, thereby optimizing the quality of the non-woven web that is produced (isotropy, weight, . . . ).

[0046] In a specific embodiment given purely by way of indication, the card 3 has been used to manufacture in parallel two condensed non-woven webs W1 and W2 out of polypropylene fibers having a length of about 40 millimeters (mm) and of approximately 2.2 dtex caliber. The diameter D of the carding drum 3h was 1500 mm; the diameter d of the accumulator transfer cylinder 3i was 700 mm; the speed of rotation of the carding drum 3h was about 212 revolutions per minute (rpm), corresponding to a circumferential speed V1 of about 1000 m/min; the speed of rotation of the accumulator transfer cylinder 3i was about 590 rpm, corresponding to a circumferential speed V2 about 1300 m/min; the speed of rotation of each combing cylinder 3j was about 91 rpm, corresponding to a circumferential speed of about 200 m/min; the speed of rotation of each condenser cylinder 3k was 162 rpm, corresponding to a circumferential speed of about 150 m/min. With reference to FIGS. 2 and 3, the angle (A) of the teeth 4 of the clothing G of the accumulator transfer cylinder 3i was about 3°; the height (H) of each tooth 4 was 3.1 mm; the pitch (p) between two rows of teeth 4 was 1.6 mm; the distance (e) between two adjacent teeth 4 in the same row was 3.3 mm.

[0047] The invention is not limited to a dual-outlet card, but can naturally be applied to cards having a single outlet, or to cards having more than two outlets. Similarly, the invention is not limited to an outlet in which the web-forming cylinders are constituted by a combing cylinder followed by a condenser cylinder, but it can be implemented with any known type of web-forming cylinder. In particular, a card can be provided in which the web-forming cylinders are combing cylinders only. Similarly, it is possible to envisage making a card in which the first web-forming cylinder is not a combing cylinder, but is a drum-backing cylinder, for example. More particularly, it would be possible for example to make a card of the invention having an outlet constituted by a drum-backing cylinder followed by a combing cylinder, or a card having an outlet formed by a drum-backing cylinder followed by a combing cylinder and by a condenser cylinder, with the drum-backing cylinder being located in both cases adjacent to the accumulator transfer cylinder 3i of the invention.

Claims

1. A card comprising a carding drum, carding members mounted at the periphery of the carding drum, and at least one card outlet having at least a first cylinder for forming a non-woven web, the card including an accumulator transfer cylinder between the carding drum and the first cylinder for forming a non-woven web.

2. A card according to claim 1, wherein, in order to be able to take up fibers from the periphery of the carding drum, the accumulator transfer cylinder has clothing comprising a plurality of teeth that are inclined relative to the radius of the accumulator transfer cylinder and oriented in the direction of rotation of said cylinder, and wherein, when the card is in operation, the accumulator transfer cylinder is driven in a direction of rotation opposite to the direction of rotation of the carding drum and at a circumferential speed greater than the circumferential speed of the carding drum.

3. A card according to claim 2, wherein the circumferential speed of the carding drum and the circumferential speed of the accumulator transfer cylinder are adjusted in such a manner that the speed ratio is greater than or equal to 1.2, and preferably greater than or equal to 1.3.

4. A card according to claim 1, wherein the accumulator transfer cylinder has clothing, and the speed of rotation of the accumulator transfer cylinder is adjusted in such a manner that when the card is in operation, the accumulator transfer cylinder picks up on each revolution of the carding drum more than 90% and preferably picks up 100% of the fibers transported at the periphery of the carding drum.

5. A card according to claim 1, wherein the diameter of the accumulator transfer cylinder is less than the diameter of the carding drum.

6. A card according to claim 1, having two outlets, each comprising a first web-forming cylinder adjacent to the same accumulator transfer cylinder.

7. A card according to claim 1, wherein the first cylinder forming a non-woven web is a combing cylinder.

8. A card according to claim 7, wherein the combing cylinder is followed by a single condenser cylinder.

9. A card according to claim 1, wherein the first cylinder for forming a non-woven web is a drum-backing cylinder.

10. A card according to claim 1, having one or more carding members mounted at the periphery of the accumulator transfer cylinder and preferably positioned in a region situated upstream from the transfer zone(s) between the accumulator transfer cylinder and each first cylinder for forming a non-woven web.

11. A method of producing a non-woven web by means of a card as specified in claim 1.

12. A method according to claim 11, wherein, on each revolution of the carding drum, the accumulator transfer cylinder is used to pick up more than 90%, and preferably to pick up 100% of the fibers transported on the periphery of the carding drum.