U.S. patent application number 12/108965 was filed with the patent office on 2008-10-23 for apparatus and method for depositing synthetic fibers to form a nonwoven.
This patent application is currently assigned to Oerlikon Textile GmbH & Co. KG. Invention is credited to ANTON MOOSHAMMER.
Application Number | 20080256757 12/108965 |
Document ID | / |
Family ID | 37667368 |
Filed Date | 2008-10-23 |
United States Patent
Application |
20080256757 |
Kind Code |
A1 |
MOOSHAMMER; ANTON |
October 23, 2008 |
APPARATUS AND METHOD FOR DEPOSITING SYNTHETIC FIBERS TO FORM A
NONWOVEN
Abstract
The invention relates to an apparatus and a method for
depositing synthetic fibers to form a nonwoven, in which the
synthetic fibers are blown through a take-up nozzle as a fiber
stream in a free space in the direction of a deposit belt.
According to the invention, the fiber stream, before impinging onto
the deposit belt, is guided by a guide segment formed between two
guide members, one of the guide members being arranged on a belt
exit side and an opposite guide members being arranged on a belt
inlet side and forming, at a distance from the take-up nozzle, an
open fiber entry gap for entry into the guide segment, and the
guide segment extending as far as the deposit belt.
Inventors: |
MOOSHAMMER; ANTON;
(Aschersleben, DE) |
Correspondence
Address: |
ALSTON & BIRD LLP
BANK OF AMERICA PLAZA, 101 SOUTH TRYON STREET, SUITE 4000
CHARLOTTE
NC
28280-4000
US
|
Assignee: |
Oerlikon Textile GmbH & Co.
KG
|
Family ID: |
37667368 |
Appl. No.: |
12/108965 |
Filed: |
April 24, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/EP2006/010234 |
Oct 24, 2006 |
|
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|
12108965 |
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Current U.S.
Class: |
19/296 |
Current CPC
Class: |
D04H 3/02 20130101; D04H
3/04 20130101 |
Class at
Publication: |
19/296 |
International
Class: |
D01G 23/00 20060101
D01G023/00 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 26, 2005 |
DE |
10 2005 051 244.5 |
Claims
1. An apparatus for depositing synthetic fibers to form a nonwoven,
said apparatus comprising: a take-up nozzle; a deposit belt which
is arranged below the take-up nozzle and which is driven so as to
be directed transversely with respect to a longitudinal side of the
take-up nozzle; and guide members arranged in a free space formed
between the take-up nozzle and the deposit belt, wherein one of the
guide members is arranged on a belt exit side and an opposite guide
member is arranged on a belt inlet side, and wherein the guide
members form, at a distance from the take-up nozzle, an open fiber
entry gap to a guide segment formed between the guide members,
which guide segment extends between the guide members as far as the
deposit belt.
2. The apparatus as claimed in claim 1, wherein the guide member
arranged on the belt exit side is formed by a rotatably mounted
roller which with the deposit belt forms a shaping gap for the
nonwoven.
3. The apparatus as claimed in claim 2, wherein the guide member
arranged on the belt inlet side is formed by a second rotatably
mounted roller which is held in contact with the deposit belt.
4. The apparatus as claimed in claim 3, wherein at least one of the
rollers has a perforated roller casing, and wherein the roller
casing is connected to a pressure chamber formed inside the
roller.
5. The apparatus as claimed in claim 4, wherein the pressure
chamber within the roller is connected to a compressed air source
or to suction extraction.
6. The apparatus as claimed in claim 3, wherein at least one of the
rollers is held in frictional contact with the deposit belt and is
configured to be driven by means of a conveying movement of the
deposit belt.
7. The apparatus as claimed in claim 3, wherein at least one of the
rollers is coupled to an electric drive.
8. The apparatus as claimed in claim 3, wherein at least one of the
rollers is assigned a ferromagnetic means which cooperates with a
magnet arranged on an underside of the deposit belt, in such a way
that a pressure force acts between the roller and the deposit
belt.
9. The apparatus as claimed in claim 8, wherein the magnet
comprises an electromagnet.
10. The apparatus as claimed in claim 1, wherein the guide member
arranged on the belt exit side or the deposit belt is assigned an
adjustment device, by means of which a shaping gap formed between
the guide member and the deposit belt can be changed.
11. The apparatus as claimed in claim 1, wherein, to change the
guide segment formed between the guide members, at least one of the
guide members is held so as to be adjustable transversely with
respect to the take-up nozzle.
12. The apparatus as claimed in claim 1, wherein an adjustable
suction port is formed, below the deposit belt by means of which
suction port a suction extraction device is connected to the
underside of the deposit belt.
13. The apparatus as claimed in claim 12, wherein the suction port
is formed between two cover plates held so as to be displaceable in
relation to one another.
14. The apparatus as claimed in claim 1, wherein the guide members
and the deposit belt are held on a lifting table which is movable
between the take-up nozzle and the deposit belt in order to change
a deposit height.
15. The apparatus as claimed in claim 1, wherein the fiber outlet
of the take-up nozzle is assigned at least one conveying means
which is held at a distance from the guide members below the
take-up nozzle.
16. A method for depositing a multiplicity of fibers to form a
nonwoven, said method comprising: blowing the fibers onto a driven
deposit belt in an arrangement in the form of a row, wherein the
fibers, before being deposited onto the deposit belt, are blown
into a guide segment formed by cooperating guide members and are
subsequently deposited at the end of the guide segment to form the
nonwoven.
17. The method as claimed in claim 16, wherein the fibers are
shaped to form the nonwoven by means of a pressure force acting
between a rotating roller and the deposit belt.
18. The method as claimed in claim 17, wherein the pressure force
between the roller and the deposit belt is generated by means of a
controllable electromagnet.
19. The method as claimed in claim 18, wherein the application of
current to the electromagnet is controlled as a function of the
fiber cross section and of a weight per unit area of the
nonwoven.
20. An apparatus for depositing synthetic fibers to form a
nonwoven, said apparatus comprising: a take-up nozzle; a deposit
belt which is arranged below the take-up nozzle and which is driven
so as to be directed transversely with respect to the longitudinal
side of the take-up nozzle; and a plurality of guide members
arranged between the take-up nozzle and the deposit belt, one of
the guide members on a belt exit side being a freely rotatable
roller which with the deposit belt forms a shaping gap, wherein
ferromagnetic means with a magnet are provided, by which a pressure
force between the roller and the deposit belt can be generated.
21. The apparatus as claimed in claim 20, wherein the magnet is of
beam-shaped design and is arranged on an underside of the deposit
belt, and wherein the ferromagnetic means is assigned to the
roller.
22. The apparatus as claimed in claim 21, wherein the ferromagnetic
means is formed by a roller casing.
23. The apparatus as claimed in claim 21, wherein the ferromagnetic
means is formed by an iron roll which is arranged freely rotatably
inside the roller.
24. The apparatus as claimed in one of claim 20, wherein, on an
inflow side of the take-up nozzle, a second roller is held freely
rotatably in contact with the deposit belt, and wherein further
ferromagnetic means with a second magnet is provided, by which the
second roller s pressed against the deposit belt.
25. The apparatus as claimed in claim 24, wherein the second magnet
is of beam-shaped design and is arranged on an underside of the
deposit belt, and wherein the ferromagnetic means is assigned to
the second roller.
26. The apparatus as claimed in claim 20, wherein the magnet is
formed by a controllable electromagnet.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a Continuation of International
Application No. PCT/EP2006/010234, filed Oct. 24, 2006, and which
designates the U.S. The disclosure of the referenced application is
incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The invention relates to an apparatus for depositing
synthetic fibers to form a nonwoven, and to a method for depositing
a multiplicity of fibers to form a nonwoven.
BACKGROUND OF THE INVENTION
[0003] In the production of a nonwoven web consisting of synthetic
fibers, a multiplicity of extruded filament strands have to be
deposited as uniformly as possible to form a sheet-like structure.
The filament strands are in this case taken up to a greater or
lesser extent, after extrusion and cooling, by a conveying fluid
and are led to a deposit belt. In order to achieve conveying and
depositing speeds which are as high as possible, methods and
apparatuses have proven particularly appropriate in which the
take-up nozzle conveys the filament strands into an open system. A
method of this type and an apparatus of this type are known, for
example, from U.S. Pat. No. 6,183,684. In this case, a take-up
nozzle is used in order to take up the synthetic fibers, after
extrusion, from a spinning device, draft them and lay them down.
The take-up nozzle has a guide duct which has a slit-shaped fiber
inlet on a top side. Shortly below the fiber inlet, a plurality of
fluid inlets issue into the guide duct, through which fluid inlets
a conveying fluid is supplied to the guide duct under the action of
an excess pressure. As a result, the fiber strands are drawn into
the take-up nozzle and accelerated within the guide duct and are
blown out as a fiber stream through the fiber outlet. At the same
time, a drafting of the fiber strands takes place, and these are
subsequently received directly, for depositing, by a deposit belt.
In this case, the fibers impinge, together with the conveying
fluid, as a fiber stream onto the deposit belt essentially
perpendicularly. By means of such apparatuses and methods,
production speeds can be achieved at which the filament strands may
reach speeds of up to 8000 m/min.
[0004] In order to influence the depositing of the synthetic fibers
on the deposit belt, it is known, furthermore, to arrange, in the
free space formed between the take-up nozzle and the deposit belt,
guide members by which the fiber flow can be varied in order to
influence the depositing of the fibers. An apparatus of this type
is known, for example, from U.S. Patent Publication No.
2002/0158362 A1. The guide members are held at a long distance from
the deposit belt, in order to generate a swirling of air so as to
give rise to a traversing movement of the fibers. Consequently,
although special effects in the depositing of a nonwoven can be
achieved, these nevertheless increasingly lose their action at
higher production speeds.
[0005] For the production of synthetic nonwoven webs, apparatuses
and methods are also known in which the take-up nozzles are
connected directly to following guide wells to form a closed
system. An apparatus of this type is known, for example, from DE
196 12 142 A1. In closed systems of this type, the fiber stream
generated by the take-up nozzle is conducted directly out of the
fiber outlet into a guide well which guides the fiber stream until
it is laid down on the deposit belt. However, closed systems of
this type have the fundamental disadvantage that, because of the
guided flow, longer drafting zones and therefore greater distances
between the take-up nozzle and the deposit belt have to be
maintained. Closed systems are therefore basically suitable only
for low and medium production or spinning speeds.
[0006] An object of the invention was to provide an apparatus and a
method for depositing synthetic fibers to form a nonwoven, of the
generic type, in which uniform and controlled layings down of the
fibers to form a nonwoven are possible even at higher spinning
speeds.
[0007] A further object of the invention is to improve an apparatus
for depositing synthetic fibers to form a nonwoven, to the effect
that, on the deposit belt, a nonwoven is generated which has an
essentially constant nonwoven thickness over the entire belt
width.
SUMMARY OF THE INVENTION
[0008] These objects and others are achieved, according to the
invention, by means of the apparatuses, and methods described and
claimed below.
[0009] Advantageous developments of the invention are defined by
the features and feature combinations of the claimed invention.
[0010] The invention possesses the advantage that the fibers can be
guided, free of surrounding influences, in a protected space for
depositing. For this purpose, the fiber stream generated by the
take-up nozzle is blown out of the free space in an open fiber
entry gap formed by the guide members, in order to be guided to the
deposit belt within a guide segment formed between the guide
members. The guide members in this case form a spatially delimited
region above the deposit belt, in which region the fibers are
deposited to form the nonwoven. It became apparent, surprisingly,
that the air swirling generated during the transition of the fiber
stream into the open fiber entry gap did not have adverse effects
on the depositing and the guidance of the fiber stream within the
guide segment.
[0011] In order as far as possible to generate low swirls at the
transition of the fiber stream out of the free space into the fiber
entry gap, the development of the invention proved particularly
appropriate in which the guide member arranged on the belt exit
side is formed by a rotatably mounted roller which with the deposit
belt forms a shaping gap for the nonwoven. In this case, both for
the fiber inlet and for the depositing of the fibers, a favorable
guide contour within the guide segment is provided, by means of
which a particularly advantageous depositing of the fiber on the
deposit belt is achieved. On account of the roller contour, the
fiber impingement angle can be influenced in such a way that the
fibers can impinge onto the deposit belt at an angle of
<90.degree.. Consequently, even at high speeds of the guided
fibers, a gentle and careful depositing of the fibers on the
deposit belt is achieved. The kinetic energy accompanying the
impingement of the fibers can advantageously be included in the
formation of the nonwoven. Moreover, the nonwoven acquires an
essential uniform thick structure over the entire width of the
deposit belt, without being damaged in the shaping gap between the
deposit belt and the roller.
[0012] In order to allow the entry of the fiber stream into the
open fiber entry gap without substantial air swirls, the
development of the apparatus according to the invention is
preferably used in which the guide member arranged on the belt
inlet side is formed by a second rotatably mounted roller which is
held in contact with the deposit belt. Moreover, in this case,
essentially wear-free sealing off with respect to surrounding
influences can be generated on the deposit belt.
[0013] The guidance of the fibers within the guide segment and the
depositing of the fibers in the lower region of the guide segment
can be influenced in a desirable way by virtue of the development
according to the invention of the apparatus, in such a way that at
least one of the rollers has a perforated roller casing which is
connected inside it to a pressure chamber formed. By the pressure
chamber being connected to a pressure source or to suction
extraction, additional air flows can be generated within the guide
segment. In this case, for example, pulsating compressed air
variations within the pressure chamber can also be formed, so that
special effects in the depositing of the nonwoven are
generated.
[0014] The drive of the rollers preferably takes place by means of
the conveying movement of the deposit belt, so that the rollers are
held in frictional contact with the deposit belt. It is also
possible, however, to assign at least one electric drive to the
rollers.
[0015] The development of the apparatus according to the invention,
in which at least one of the rollers is assigned a ferromagnetic
means which cooperates with a magnet, preferably an electromagnet,
arranged on an underside of the deposit belt, in such a way that a
pressure force acts between the roller and the deposit belt, is
particularly advantageous in the formation of a shaping gap between
the roller and the deposit belt. Fine adjustment can thereby be
carried out, so that a pressure force optimal in each case acts
between the roller and the deposit belt as a function of the
filament strength of the fibers and of the weight per unit area of
the nonwoven. Moreover, influencing the pressure force between the
roller and the deposit belt allows an optimal sealing function with
respect to the surroundings, so that, for example, a sucking in of
extraneous air or the generation of air vortices at the sealing
points is avoided.
[0016] Since apparatuses of this type are conventionally used for
the production of different nonwovens, the development of the
invention leads to particular flexibility in which the guide member
arranged on the wall exit side or the deposit belt is assigned a
height adjustment device, by means of which a shaping gap formed
between the guide member and the deposit belt can be changed. In
addition, a further optimization for the guidance and depositing of
the fibers is afforded in that, to change the guide segment formed
between the guide members, at least one of the guide members is
held so as to be adjustable transversely with respect to the
suction nozzle.
[0017] In order to receive and discharge continuously the air
quantity supplied through the suction nozzle, the deposit belt has
formed below it an adjustable suction port, by means of which a
suction extraction device is connected to the underside of the
deposit belt. In this case, the suction port can be varied in its
size between two cover plates held displaceably with respect to one
another, so that, depending on the depositing of the fibers, an
optimized and uniform reception and discharge of the conveying
fluid take place.
[0018] A further improvement in the flexibility of the apparatus
according to the invention is afforded in that the guide members
and the deposit belt are held on a lifting table which is movable
between the take-up nozzle and the deposit belt in order to change
a deposit height. By the guide members being tied up to the deposit
belt, the entire free space between the guide members and the
take-up nozzle is available for adjustment. Furthermore, the
take-up nozzle could likewise be designed to be adjustable in
height.
[0019] Moreover, it is proposed that the outlet orifice of the
take-up nozzle be assigned at least one conveying means which is
held at a distance from the guide members below the take-up nozzle.
Further fiber guidance relevant for the formation of the nonwoven
can consequently be set.
[0020] The method according to the invention for depositing a
multiplicity of fibers to form a nonwoven combines the particular
advantages of an open system, in which the fiber stream is blown
directly into a free space, with a controlled and reproducible and
also reliable depositing of the fibers to form a nonwoven.
Surrounding influences caused, for example, by extraneous air are
reduced to a minimum during depositing in spite of the open
system.
[0021] The development of the method according to the invention in
which the fibers are shaped to form the nonwoven by means of a
pressure force acting between a rotating roller and the deposit
belt constitutes a particularly advantageous method variant in
which, on the one hand, a high sealing action of the guide segment
is generated and, on the other hand, nonwoven formation with an
essentially constant nonwoven thickness is generated without damage
to the nonwoven. It proved particularly advantageous if the
pressure force between the roller and the deposit belt is generated
by means of a controllable electromagnet. Optimized pressure forces
can thus be set, depending on the filament cross section and
nonwoven strength.
[0022] The apparatus according to the invention having the features
according to one embodiment constitutes an advantageous design for
generating by magnetic means a pressure force acting between a
roller and a deposit belt.
[0023] For this purpose, preferably, the magnet is of beam-shaped
design and is arranged on an underside of the deposit belt. The
magnetically conveying means cooperating with the magnet are
assigned to the roller, so that an attraction force determined by
the magnet acts on the roller. Such a design has the advantage,
moreover, that the roller assumes an essentially unchanged position
on the deposit belt.
[0024] The ferromagnetic means may in this case be formed directly
by a roller casing or, alternatively, by an iron roll which is
arranged freely rotatably inside the roller.
[0025] In order to obtain optimized sealing off of the deposit
region both on the exit side and on the inlet side of the deposit
belt, preferably a second roller is also held freely rotatably in
contact with the deposit belt on the inflow side of the take-up
nozzle, said second roller having a ferromagnetic means and
cooperating with a second magnet on the underside of the deposit
belt.
[0026] So that the pressure forces between the roller and the
deposit belt can be influenced, particularly for shaping the
nonwoven, the magnet is preferably formed by a controllable
electromagnet, so that, by current being applied to the
electromotor, the intensity and therefore the magnitude of the
pressure force can be varied.
[0027] The apparatus according to the invention and the method
according to the invention are distinguished by a stable and
reproducible depositing of the fibers to form a nonwoven, high
spinning and production speeds being possible. In this case, any
desired setting can be carried out as a function of the fiber type,
fiber material and nonwoven requirement. There is also the
possibility of carrying out the settings by means of controllable
actuators which, for example, are activated in an automated manner
by means of a control device according to the stipulation of
process or product parameters.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] The apparatus according to the invention and the method
according to the invention are described in more detail below by
means of some exemplary embodiments, with reference to the
accompanying figures in which:
[0029] FIG. 1 illustrates diagrammatically a view of a first
exemplary embodiment of the apparatus according to the
invention;
[0030] FIG. 2 illustrates diagrammatically a cross-sectional view
of a further exemplary embodiment of the apparatus according to the
invention:
[0031] FIG. 3 illustrate diagrammatically a cross-sectional view of
a further exemplary embodiment of the apparatus according to the
invention; and
[0032] FIG. 4 illustrates diagrammatically a cross-sectional view
of a further exemplary embodiment of the apparatus according to the
invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0033] FIG. 1 shows diagrammatically a first exemplary embodiment
of the apparatus according to the invention for depositing
synthetic fibers to form a nonwoven and for carrying out the method
according to the invention.
[0034] The exemplary embodiment according to FIG. 1 shows a
parallelepipedal take-up nozzle 1 which is arranged in the usual
way below a spinning device. Take-up nozzles of this type are
generally known and are explained in more detail, for example, in
U.S. Pat. No. 6,183,684 B1. To that extent, reference is made to
the publication mentioned and only the essential components are
mentioned below.
[0035] The take-up nozzle 1 has a middle conveying duct 5 which is
delimited on a top side of the take-up nozzle 1 by a fiber inlet 2
and on the underside of the take-up nozzle 1 by a fiber outlet 3.
The conveying duct 5 is of slit-shaped design and extends
essentially over the entire length of the parallelepipedal take-up
nozzle 1. On the longitudinal sides of the conveying duct 5, a
plurality of fluid inlets, not illustrated here, are formed, which
are connected to a fluid connection 4. By means of the fluid
connection 4, a conveying fluid is supplied which has an excess
pressure with respect to the atmosphere in the conveying duct
5.
[0036] The take-up nozzle 1 is arranged at a distance above a
deposit belt 6. The deposit belt 6 has a belt width which extends
over the entire length of the take-up nozzle 1. The deposit belt 6
is preferably guided as an endless belt via a plurality of
conveying rolls and is driven so as to be directed transversely
with respect to the longitudinal side of the take-up up nozzle 1.
The deposit belt 6 therefore moves continuously in a guidance
direction which is identified in the figure by an arrow. The
deposit belt 6 is of air-permeable design, a suction extraction
device 31 being arranged on the underside of the deposit belt 6 in
a deposit region formed vertically below the take-up nozzle 1.
[0037] In the region between the take-up nozzle 1 and the deposit
belt 6, a travel is formed which is divided into a free space 17
formed directly below the take-up nozzle 1 and a guide segment 9
assigned to the deposit belt 6. The guide segment 9 is formed by
the guide members 7.1 and 7.2 which on a top side form, opposite
the take-up nozzle 1, a fiber entry gap 8. For this purpose, the
guide member 7.1 is arranged on a belt exit side 10 and the guide
member 7.2 is arranged on the opposite belt inlet side 11. In this
case, the guide members 7.1 and 7.2 are formed in each case by a
roller 12.1 and 12.2 held so as to be rotatably mounted. The roller
12.1 on the belt exit side 10 and the roller 12.2 on the belt inlet
side 11 are in each case in frictional contact with the deposit
belt 6, so that the rotational movement of the rollers 12.1 and
12.2 is generated by friction by means of the conveying movement of
the deposit belt 6. The roller 12.2 in this case bears directly
against the surface of the deposit belt 6 or on a coating material.
The roller 12.1 on the belt exit side 10 forms with the top side of
the deposit belt 6 a shaping gap 19 by means of which a nonwoven 21
is deposited and shaped.
[0038] The fiber entry gap 8 formed on the top side of the rollers
12.1 and 12.2 is of essentially funnel-shaped design with respect
to the free space 17 due to the roller casings of the rollers 12.1
and 12.2. The interspace between the rollers 12.1 and 12.2 forms
the guide segment 9 in which the fiber stream blown in via the
fiber entry gap 8 is guided for depositing onto the deposit belt 6.
The guide segment 9 extends as far as the top side of the deposit
belt 6, the rollers 12.1 and 12.2 in each case providing shielding
with respect to the surroundings. Owing to the direct frictional
contact between the rollers 12.1 and 12.2 and the deposit belt 6
and also the nonwoven surface of the nonwoven 21, sealing off with
respect to extraneous air is achieved.
[0039] The rollers 12.1 and 12.2 have in each case a perforated
roller casing 13 which is gas-permeable. Inside the rollers 12.1
and 12.2 is provided in each case a pressure chamber which is
connected to a suction source 16 or to a pressure source 18 via an
air connection 15. In the exemplary embodiment according to FIG. 1,
the inner pressure chamber 14 of the roller 12.2 is coupled to the
suction source 16. As a result, a uniform suction action is
generated on the roller casing 13 and leads to the deflection and
guidance of the fibers 20 within the guide segment 9. The
deflection of the fibers 20 within the guide segment 9 is also
increased in that the pressure chamber of the roller 12.2 is
coupled to a pressure source 18. A uniform blowing flow can
consequently be generated on the roller casing 13 of the roller
12.2.
[0040] During operation, a conveying fluid is supplied to the
take-up nozzle 1. The conveying fluid used is preferably compressed
air from a compressed air source, which flows into the conveying
duct 5 with an excess pressure in the range of 0.1 to 5 bar,
preferably in a range of 0.5 to 3 bar excess pressure. As a result,
the fiber strands 20 threaded into the conveying duct 5 via the
fiber inlet 2 are taken up continuously from a spinning device, not
illustrated here. In the spinning device, the fibers are melt-spun
beforehand from a polymer material in an arrangement in the form of
a row and are subsequently cooled. Within the conveying duct 5, the
fiber strands 20 are accelerated by the conveying fluid and are
blown out jointly through the fiber outlet 3 as a fiber stream into
the free space 17. The fiber stream which is composed of the fibers
and the conveying fluid is in this case blown perpendicularly
through the fiber outlet 3 in the direction of the deposit belt 6.
After running through the free space 17, the fiber stream, together
with the fiber strands 20, is blown into the fiber entry gap 8
formed by the guide members 7.1 and 7.2. Owing to the shape and
configuration of the guide segment 9 and of the guide members 7.1
and 7.2, the fiber stream is guided in the direction of the deposit
belt 6. Within the guide segment 9, the fiber strands 20 impinge
onto the deposit belt 6 at an impingement angle desired by the
fiber stream being influenced and on the surface of the deposit
belt 6 form the nonwoven 21 which is discharged continuously in the
conveying direction by the deposit belt 6. The suction flow
generated on the roller 12.1 on the belt exit side 10 causes a
deflection of the fiber stream, so that the fiber strands 20
impinge onto the deposit belt 6 at an impingement angle of
<90.degree.. In this case, a particularly careful depositing of
the fibers takes place, so that, even at high fiber speeds in the
range 3500 m/min. to 8000 m/min., no intensive catching between the
surface of the deposit belt 6 and the individual fibers 20 occurs.
Moreover, the shaping gap 19 set by the roller 12.1 and the deposit
belt 6 will cause the nonwoven 21 to acquire a nonwoven thickness
which is essentially constant over the entire belt width. Damage to
the nonwoven surface is ruled out on account of the rotational
movement of the roller 12.1.
[0041] The apparatus according to the invention and the method
according to the invention thus allow a uniform reproducible
depositing of a nonwoven which can take place in a controllable way
even at high fiber speeds. In this case, on the one hand, the
advantages of the high draft, which are known from the blowing of
the fiber stream out into a free space, and also the deposit
mechanisms known per se only in closed systems are advantageously
combined by virtue of the invention. In spite of the reservation
that air swirls occur at the transition between the free space and
the guide segment, it was possible, surprisingly, to generate
highly uniform and relatively smooth fiber stream profiles. In
particular, configuring the guide members as rollers afforded a
very gentle transition of the fiber stream out of the free space to
the guide segment.
[0042] FIG. 2 shows a further exemplary embodiment of the apparatus
according to the invention. The exemplary embodiment according to
FIG. 2 is essentially identical to the exemplary embodiment
described above, and therefore reference is made to the
abovementioned description and only the differences are explained
below.
[0043] In the exemplary embodiment, illustrated in FIG. 2, of the
apparatus according to the invention, the guide members 7.1 and 7.2
assigned to the deposit belt 6 are formed on the belt exit side 10
by a roller 12.1 and on the belt inlet side 11 by an actuating wall
27. The actuating wall 27 has in the lower region a flexible
sealing lip 32 which bears with a free end against the surface of
the deposit belt 6 or of a coating material. The actuating wall 27
is held pivotably on a carrier 28, the pivoting movement of the
actuating wall 27 being implementable by means of an actuator 29.
The guide member 7.1 arranged on the opposite wall exit side 10 is
formed by the roller 12.1 which is designed essentially identically
to the roller shown in FIG. 1. The roller 12.1 is mounted rotatably
on a bearing carrier 25. The bearing carrier 25 is held via a
holder 26, the bearing carrier 25 being designed to be adjustable
both vertically and horizontally on the holder 26. Thus, on the one
hand, the size of the shaping gap 19 between the deposit belt 6 and
the roller 12.1 can be varied and, on the other hand, the guide
segment 9 between the actuating wall 27 and the roller 12.1 can be
varied.
[0044] A conveying means 33.1 and 33.2 is arranged in each case on
each side of the take-up nozzle 1 directly on the side of the fiber
outlet 3. The conveying means 33.1 and 33.2 are in this case formed
by pivotable guide battens which are held pivotably on the
underside of the take-up nozzle. By the conveying means 33.1 and
33.2 arranged on the outlet side of the take-up nozzle 1,
additional flow variations of the fiber stream can be generated,
which influence both entry into the fiber entry gap 8 and the
depositing of the fiber strands 20.
[0045] For discharge and for assisting the depositing of the fibers
for forming a nonwoven, a suction extraction device 31 is arranged
on the underside of the deposit belt 6. In this case, the suction
extraction action of the suction extraction device 31 is limited to
the deposit region of the guide segment 9. The suction extraction
device 31 has an adjustable suction port 34 which is assigned
directly to the deposit region on the deposit belt 6. The suction
port 34 is in this case formed between two displaceably arranged
cover plates 35.1 and 35.2. Each of the cover plates 35.1 and 35.2
can be displaced horizontally in relation to one another.
[0046] In the exemplary embodiment illustrated in FIG. 2, the
pressure chamber 14 within the roller 12.2 is likewise connected to
a suction source, so that a suction flow prevails on the roller
casing 13. A deflection of the fiber stream in the direction of the
roller 12.1 can consequently be generated, so that a gentle
depositing of the fibers, even at very high fiber speeds,
occurs.
[0047] FIG. 3 illustrates diagrammatically a cross-sectional view
of a further exemplary embodiment of the apparatus according to the
invention. The set-up and functioning of the exemplary embodiment
are essentially identical to the exemplary embodiment according to
FIG. 1, and therefore reference is made to the abovementioned
description and only the differences are explained at this
juncture.
[0048] In the exemplary embodiment, illustrated in FIG. 3, of the
apparatus according to the invention, the guide members 7.1 and 7.2
assigned to the deposit belt 6 for forming the guide segment 9 are
formed in each case by a rotatable roller 12.1 and 12.2. Each of
the rollers 12.1 and 12.2 is in this case held by a bearing carrier
25 and a holder 26. The bearing carrier 25 is in each case designed
so as to be adjustable in the conveying direction of the deposit
belt 6 and opposite to the conveying direction of the deposit belt
6 on the holder 26. The bearing carrier 25 of the roller 12.1 is
additionally designed to be adjustable vertically for setting a
shaping gap 19 between the roller 12.1 and the deposit belt 6.
[0049] In order to obtain reliable frictional contact between the
rollers 12.1 and the deposit belt 6 and also the roller 12.2 and
the deposit belt 6, each roller 12.1 and 12.2 is assigned in each
case ferromagnetic means 22 and a magnet 23. The design of the
ferromagnetic means 22 and of the magnet 23 is identical for each
roller 12.1 and 12.2, and therefore the design is explained in more
detail by the example of the roller 12.1. The ferromagnetic means
22 is formed directly by the roller casing 13 which consists of a
ferromagnetic material. On the underside of the deposit belt 6 is
provided a magnet carrier 36 which extends essentially over the
entire belt width and which carries the beam-shaped magnet 23. The
magnet 23 is preferably formed by an electromagnet which, by
current being applied, exerts magnetization and consequently an
attraction force with respect to the roller casing 13. The roller
casing 13 of the roller 12.1 is thus attracted in the direction of
the deposit belt 6. In this case, a pressure force acting between
the roller 12.1 and the deposit belt 6 builds up and acts directly
on the nonwoven 21 in the shaping gap 19. The application of the
current to the electromagnet 23 is in this case selected in such a
way that, on the one hand, sufficient sealing off with respect to
the inflow instances of extraneous air is obtained and, on the
other hand, no damage to the nonwoven 21 occurs.
[0050] On the opposite side, the roller 12.2 is attracted in the
same way by means of a casing 13 formed from ferromagnetic material
and the second magnet 23 arranged on the underside of the deposit
belt 6, so that the roller casing 13 is held directly against the
surface of the deposit belt 6 and leads to a sealing off of the
guide segment 9 between the rollers 12.1 and 12.2.
[0051] In the exemplary embodiment illustrated in FIG. 3, the
pressure chamber 14 formed in the roller 12.1 is connected to a
pressure source and the pressure chamber formed in the roller 12.2
is connected to a suction source. An essentially perpendicular
depositing of the fiber strands 20 on the deposit belt 6 is thus
achieved.
[0052] In the free space 17, two conveying means 33.1 and 33.2 are
assigned directly to the fiber outlet 3 of the take-up nozzle 1,
the conveying means 33.1 and 33.2 being formed in each case by
freely rotatable rolls which are designed to be adjustable in their
position in and opposite to the conveying direction of the deposit
belt.
[0053] The function of the apparatus for forming the nonwoven, as
illustrated in FIG. 3, is identical to the preceding exemplary
embodiments, and therefore no further description of this is
given.
[0054] FIG. 4 shows a further alternative to the apparatus
illustrated in FIG. 3, the mount of the rollers 12.1 and 12.2 not
being illustrated in any more detail.
[0055] To fix the rollers 12.1 and 12.2, the ferromagnetic means 22
is formed in each case by an iron roll 37 which is arranged
rotatably inside the roller 12.1 or the roller 12.2. By means of
the magnet 23 arranged on the underside of the deposit belt 6, the
iron roll 37 is attracted in the direction of the deposit belt 6
and leads to the reliable bearing of the roller 12.1 against the
top side of the nonwoven 21 or to a reliable bearing of the roller
12.2 against the top side of the deposit belt 6. The magnet
assigned to the roller 12.1 on the belt exit side 10 is designed as
an electromagnet 23 which can be activated via a control unit 38
and a control device 39. In this case, process data, such as, for
example, fiber cross sections and weight per unit area or nonwoven
thickness, can be preset for the control device 39. By means of a
stored optimization program, a current size is determined from the
process parameters and is predetermined via the control unit 38 for
the application of current to the electromagnet 23. The application
of current to the electromagnet 23 leads to an attraction force and
consequently to a pressure force between the roller 12.1 and the
deposit belt 6, said pressure force being adapted to the respective
process parameters.
[0056] In the design, illustrated in FIG. 4, of the apparatus
according to the invention, the deposit belt 6 and the guide
members 7.1 and 7.2 are arranged jointly on a lifting table 30. For
this purpose, a conveying roll 40 of the deposit belt 6 is
supported on the lifting table 30 via a roll carrier 41. The
lifting table 30 is designed to be adjustable in height in the
direction of the take-up nozzle 1, so that the deposit height which
extends between the pick-up nozzle 1 and the deposit belt 6 can be
varied. In this case, the travel formed by the free space 17 can be
utilized for adjusting the deposit height. Usually, in the
apparatus according to the invention, deposit heights in the range
of 50 to 500 mm are set. Alternatively, the take-up nozzle could be
designed to be adjustable in height.
[0057] The exemplary embodiments, illustrated in FIG. 1 to 4, of
the apparatus according to the invention for carrying out the
method according to the invention are given as examples in terms of
the set-up and arrangement of the guide members. It is essential in
this case that the fibers, shortly before they impinge on the
deposit belt, are guided by a guide segment closed with respect to
the deposit belt. In particular, in this case, guide members are
suitable which allow a stable and reproducible guidance and
depositing of the fiber strands.
* * * * *