The invention relates to a device for solidifying a material web according to the precharacterizing part of claim 1.
From EP 0 859 076 A2, there is known a device for solidifying the fibers of a material web made of natural and/or synthetic fibers of a random type, wherein a belt-drum type compacting of the fiber web is performed. Said device comprises the following features and respectively is designed in the manner outlined hereunder:
The device of this type has the advantage that, between the two endless belts, the pre-nonwoven, i.e. the voluminously advancing fiber sheet, will in a slowly increasing manner and at uniform pressure be compacted from the top toward the bottom without shear stress, and will be wetted on the needling drum only when being held tight between the two endless belts. This construction, however, is complex and too expensive for certain products.
Known from EP 1 126 064 B1 is a device which simplifies the compacting as well as the first wetting of the nonwoven. In this known device, a band-band type compacting is provided, and the device comprises the following features and respectively is designed in the manner outlined hereunder:
Due to the technical expenditure, also this construction is too cost-intensive for some products.
DE 10 2005 055 939 B3 shows a nozzle beam for generating fluid jets which serve for solidifying a fiber web. The nozzle beam comprises an exchangeable nozzle beam which includes the discharge openings for the fluid. The discharge openings can be arranged in a row but also in two or more rows extending parallel to each other. The discharge openings have a mutual distance and a diameter which are adapted to the applicational use. As a fluid, one can use pressurized water but, generally, also overheated steam.
It is an object of the present invention to provide a simple device for compacting and first treatment of a pile consisting of fibers and/or filaments.
The above object is achieved by the features defined in the device claim. Advantageous modifications of the invention are indicated in the subclaims.
The invention starts from a device for solidifying a material web formed of fibers and/or filaments, said device comprising a screen belt carrying the material web, a nozzle beam arranged above the screen belt for subjecting the material web to a pressurized fluid in the form of a plurality of fluid jets arranged in at least one row, and a suction device comprising a suction gap, said suction device being disposed below the screen belt and interacting with the nozzle beam, wherein the fluid jets hit the material web in the surface area of the suction gap.
According to the invention, it is provided that the application of fluid is performed in the rear region of the suction gap as viewed in the conveying direction of the material web. The material web, i.e. the fiber and/or filament pile, is not subjected to any mechanical compacting, condensation or guidance until the application of fluid. By the enlarged suction passage area ahead of the fluid beams, the fiber and/or filament pile will be stabilized and—in dependence on the strength of the passing suction—will also be slightly condensed. Further, it is prevented by the invention that the fiber and/or filament pile being moved in the direction of the application of fluid could be buckled by the fluid jets or that folds could be generated on its surface. In this manner, disturbances in the quality of the nonwoven are avoided.
In the way of modifications, the following is provided:
An embodiment of the invention will be explained hereunder with reference to the drawing.
An endless transport belt S, formed as a screen belt and tensioned in a linear manner about deflection rollers, not shown, carries a material web F comprising fibers and/or filaments, said material web being provided, by a carding or spunbond plant, as an uncondensed pile in a largely unsolidified state and being transported in the direction indicated by the arrow. Above the transport belt S with the material web F, a nozzle beam D is arranged across the width of the material web F, the bottom side of said nozzle beam being provided with a plurality of discharge openings for pressurized fluid. In the present embodiment, the fluid is highly pressurized water, and, correspondingly, the pile of the material web F is subjected to a plurality of water jets W. The lined-up discharge openings for the water jets W are arranged in an exchangeable nozzle strip, not shown. It is also possible to use a nozzle strip comprising discharge openings arranged in a plurality of mutually spaced rows.
Below the transport belt S carrying the material web F, a suction device A is arranged which via a conduit system is connected to a separator AS having a suction ventilator SV disposed downstream of it. Within said separator AS, the water will be separated from the water-air mixture, be removed by the suction pump arranged downstream of the separator and be supplied to a water treatment unit, not shown.
Said suction device A is a chamber extending across the width of transport belt S and delimited in the transport direction of material web F by two bars L1 and L2 made of plastic. On the format edges of material web F, the suction gap formed by said bars L1,L2 is closed. In the Figure, the visual representation of the bars L1,L2 of nozzle beam D and particularly the dimensional relations of the components are rendered in a purely schematic manner.
According to
By the asymmetric orientation of the water jets relative to the suction gap (bars L1,L2), the material web F is subjected to a stronger passage of suction in the front region (distance a to bar L1) than in the rear region (distance b to bar L2). This volumetrically stronger passage of suction force through the material web F in the front region (a) has a stabilizing effect on the pile which is running against the water jets W and which thereby is subjected to a compressive force against the transport direction.
The stronger passage of suction force through the pile before the water jets W is effective to avoid a bulging of the pile before the first solidifying by the water jets W. Bulging of the pile can generate irregularities in the product which cause a negative visual appearance, e.g. in the form of sites with excessive density or in the form of clouds, and on the other hand have an adverse effect on the strength of the nonwoven. Ultimately, the bulging could reach such an extent that the pile is caused to contact the nozzle beam D and is damaged. This would cause disturbances and interruptions in the production process.
Not illustrated in the Figure is a further embodiment of the invention wherein, before the nozzle beam D as viewed in the conveying direction of the material web F, a blowing device is arranged for blowing air onto the surface of the material web in the region a of the suction gap.
In a practical example, the material web F to be solidified consisted of a spunbonded nonwoven of polypropylene (PP) with a yarn count of 1.8 den. After laying, the spunbonded nonwoven was merely slightly calendered and subsequently was hydrodynamically treated according to the invention. The water pressure in the first nozzle beam D was 80 bar, and the suction device was subjected to an underpressure of 120 mbar. The suction gap had a width b of 12 mm, and the water jets W had a distance a of 10 mm from the front bar L1 of the suction gap. These measures allowed to perform the first hydrodynamic needling without compacting by use of a noticeably lower pressure, whereby the danger of bulging of the pile was further reduced. As compared to a central orientation of the water jets relative to the suction gap, it was possible to finally produce a distinctly more homogenous nonwoven in a disturbance-free manner.
S screen belt, transport belt
F material web, pile
A suction device, suction gap
L1 bar, front bar
L2 bar, rear bar
AS separator
SV suction ventilator, suction air generator
SP suction pump
D nozzle beam
W water jet, application of fluid
b width of suction gap
a distance of water jet from front bar L1
c distance of water jet from rear bar L2
Number | Date | Country | Kind |
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10 2010 009 275.4 | Feb 2010 | DE | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/DE2011/000085 | 1/29/2011 | WO | 00 | 9/24/2012 |