U.S. patent application number 13/049401 was filed with the patent office on 2011-09-22 for fiber composite acoustic damping material.
This patent application is currently assigned to Groz-Beckert KG. Invention is credited to Thomas Kuhl, Miroslav Svejda.
Application Number | 20110226547 13/049401 |
Document ID | / |
Family ID | 42555559 |
Filed Date | 2011-09-22 |
United States Patent
Application |
20110226547 |
Kind Code |
A1 |
Kuhl; Thomas ; et
al. |
September 22, 2011 |
Fiber Composite Acoustic Damping Material
Abstract
A damping material (11) in accordance with the invention
consists of a ground material that is composed of fibers that are
in loose connection with each other. For example, the fibers are
minimally interlooped with each other or also glued to each other.
This ground material is condensed in some areas in that the fibers
are reoriented or interlooped with each other to a greater degree
or glued to each other. Consequently, zones (17) and (18) of
different densities are formed, thus making it possible to increase
and adjust, as desired, the sound-damping effect of the damping
material.
Inventors: |
Kuhl; Thomas; (Inzigkofen,
DE) ; Svejda; Miroslav; (Dobra Voda, CZ) |
Assignee: |
Groz-Beckert KG
Albstadt
DE
|
Family ID: |
42555559 |
Appl. No.: |
13/049401 |
Filed: |
March 16, 2011 |
Current U.S.
Class: |
181/294 |
Current CPC
Class: |
B32B 2262/0276 20130101;
E04B 1/84 20130101; G10K 11/162 20130101; B32B 2262/14 20130101;
B32B 5/26 20130101; B32B 2262/105 20130101; B32B 2262/0207
20130101; B32B 2262/101 20130101; B32B 2262/062 20130101; B32B
2262/02 20130101; B32B 2262/08 20130101; B32B 5/142 20130101; B32B
5/022 20130101; D04H 1/495 20130101; B32B 5/12 20130101; B32B
2307/102 20130101 |
Class at
Publication: |
181/294 |
International
Class: |
E04B 1/84 20060101
E04B001/84 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 17, 2010 |
EP |
10 002 801.8 |
Claims
1. Acoustic damping material (11) consisting of a random-fiber
non-woven body (10) that is made of interlooped fibers (13, 14, 15,
16) and has at least two spatial zones (17, 18, 28, 29) displaying
different degrees of fiber interlooping.
2. Damping material as in claim 1, characterized in that the two
zones (17, 18, 28, 29) displaying different degrees of fiber
interlooping have different fiber densities.
3. Damping material as in claim 1, characterized in that the
spatial zones (17, 18, 28, 29) are arranged in an irregular
pattern.
4. Damping material as in claim 1, characterized in that the fibers
in the zones (17) displaying a lower degree of fiber interlooping
are oriented predominantly in one plane, while, in the zones (18,
28, 29) displaying a greater degree of interlooping, a larger
proportion of said fibers is oriented in a direction perpendicular
to said plane.
5. Damping material as in claim 1, characterized in that the zones
(18, 28, 29) displaying the greater degree of fiber interlooping
have the form of strip-shaped regions.
6. Damping material as in claim 5, characterized in that the zones
(18, 28, 29) are arranged at different distances from each other
and parallel to each other.
7. Damping material as in claim 1, characterized in that the
random-fiber non-woven body (10) comprises several layers (32, 33)
that are made of interlooped fibers (25, 26), whereby at least one
layer (32) of said layers has the zones (17, 34, 35) displaying
different degree of fiber interlooping.
8. Damping material as in claim 7, characterized in that at least
two of said layers (32, 33) have zones (17, 34, 35, 36, 37)
displaying different degrees of fiber interlooping, said zones
being arranged differently.
9. Damping material as in claim 8, characterized in that the zones
(17, 34, 35, 36, 37) of the layers (32, 33) are strip-shaped and
are superimposed in a manner so as to cross each other.
10. Damping material as in claim 1, characterized in that the fiber
body (10) contains interstices (27, 39) that are free of fibers or
have a fiber density that is considerably reduced compared to the
surrounding fiber body (10).
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] The present application claims the priority of European
Patent Application No. 10 002 801.8, filed Mar. 17, 2010, the
subject matter of which, in its entirety, is incorporated herein by
reference.
BACKGROUND OF THE INVENTION
[0002] The invention relates to an acoustic damping or absorbing
material in the manner of a body consisting of fibers. In
particular, the invention relates to such a spatially configured,
i.e., not simply planar, damping or absorbing material.
[0003] Acoustic damping materials consisting of the most diverse
materials such as mineral wool, glass wool or natural or synthetic
fibers have been known. In each case, the damping material is to
absorb sound energy, i.e., the sound waves are to be attenuated in
that the vibration energy of the sound waves is converted by
friction into thermal energy. In doing so, the formation of
resonances and the formation of standing waves is to be
prevented.
[0004] Fiber materials with non-ordered fibers may display a high
acoustic damping effect. In doing so, it is possible--in
principle--to design the felt bodies so as to be relatively
variable, as has been known from document EP 2 034 072 A1. This
publication deals with a hygiene article such as, for example,
sanitary materials. In order to produce such materials, a non-woven
fibrous web is needled along strip-shaped areas with different
strengths, so that elongated parallel-oriented zones displaying a
higher fiber density are achieved in the material. The extent to
which such a material can be employed for a use other than in the
medical and nursing fields is open.
[0005] It is the object of the invention to provide an acoustic
damping material displaying improved efficacy.
SUMMARY OF THE INVENTION
[0006] The damping material in accordance with the invention forms
a random fiber non-woven body, i.e., a body consisting of
non-ordered fibers. In this body, the fibers may be also be
arranged parallel to each other in zones. The fibers may be
interlooped, in which case the degree of interlooping may be
different in at least two different zones. The random-fiber
non-woven body may be produced, for example, in that a loose
fibrous web or non-woven (for example of polyester) is condensed by
mechanical or also thermal action in specified zones. In doing so,
an acoustic damping material displaying spatially varying densities
is produced. In this case, the invention offers a means to produce
this damping material in a cost-favorable manner.
[0007] The acoustic damping material can be provided in the form of
a mat. The mat may be made of glass fiber wool or of mineral wool
or also of other materials, for example. The fibers of the mat in
the fibrous web are preferably arranged next to each other, loosely
but still holding together. This can be achieved in that the fibers
are interlooped with each other in such a manner that at least a
loose cohesion of the mat exists. The fibers may be aligned
parallel or may be arranged so as to be crossed superimposed in
layers by means of a cross-laying process.
[0008] For example, the fibrous web may first be made available by
using carding methods or spunbonding processes, these being known
per se. Due to a zone-wise condensation, the loose fibrous web is
converted into the desired state in that zones are created, wherein
the degree of fiber interlooping is greater compared with the
remaining body or the remaining mat. Increased fiber interlooping
may be achieved by mechanical needling, e.g., with the use of
felting needles, by condensing with water jets or similar
techniques. Alternatively, local condensing may be achieved, for
example by thermal compression. By condensing the fiber body, the
condensed zones become more compact, whereby more interlooped
fibers are counted by unit of volume than in the non-condensed
material.
[0009] The acoustic damping material may be provided in the form of
random-fiber non-woven bodies displaying defined geometric shape or
also in the form of mats that are cut to the desired size and
dimensions prior to use. It is characteristic of the damping
material that at least two, but preferably more, zones displaying
at least two degrees of fiber interlooping do exist.
[0010] The zones displaying different degrees of fiber
interlooping, preferably also have different fiber densities. As a
result of this, zones of different pore volume and different
acoustic hardness are formed in the damping material, so that a
strong acoustic damping effect can be achieved.
[0011] The zones displaying differently strong fiber interlooping
may be arranged in a regular or preferably irregular pattern, as a
result of which a broad-spectrum acoustic damping effect can be
achieved.
[0012] The damping material in accordance with the invention may be
produced of uniform fibers or also of different fibers, for
example, of fibers having different lengths and/or thicknesses, of
fibers that consist of a uniform material or also of fibers that
consist of different fibers, i.e., fiber mixtures. If necessary,
fibers having different dimensions or consisting of different
materials may also be concentrated in different zones so as to also
form zones of different materials in addition to the zone-specific
different degrees of fiber interlooping.
[0013] Preferably, the fibers in zones of minimal fiber
interlooping are predominantly oriented in one plane (or in crossed
position), whereby the fibers in the plane may be selectively
oriented in parallel direction or also in different directions,
i.e., they cross one or more times, but interloop minimally. If the
damping material is provided in the form of a mat, the fibers--in
particular in zones of minimal fiber interlooping--are preferably
predominantly in the plane of this mat. In zones of more fiber
interlooping, the fibers--at least preferably--are oriented in an
increased proportion in a direction perpendicular to this plane. As
a result of this, condensed zones are formed that impart the mat or
the other fiber body with a particular mechanical stability and,
specifically, with cohesion.
[0014] The zones of increased fiber interlooping may be arranged as
regularly or irregularly formed islands in the damping material.
Preferably, they have the form of strip-shaped--again preferably
straight--regions that, for example, may extend in transverse
direction of the mat and/or in longitudinal direction of the mat.
Furthermore, they may extend in oblique directions, for example
extend diagonally. Preferably, the condensed zones extend through
the entire mat thickness, i.e., from the upper side to the
underside of said mat.
[0015] Considering a particularly advantageous embodiment, the
damping materials comprises at least two layers, wherein zones with
different degrees of fiber interlooping are provided, in which case
these two zones may be arranged differently in the two layers, for
example, not in a registered manner. It is possible to provide in
these layers condensed zones, i.e., zones with a greater degree of
fiber interlooping, said zones being connected to the respectively
other layer. For example, the condensed zones in these layers may
be produced by needling, by water-jet condensing or the like. A
fiber body or a corresponding mat can be produced as a layer. As
previously described, such a layer is produced, for example, by
zone-wise compacting the fiber body. After superimposing two or
more such layers, they, in turn, may experience compacting in some
areas, in which case the degree of fiber interlooping increases at
certain points or in zones (regions) and, in doing so, a connection
is also established between the layers.
[0016] Hereinafter, exemplary embodiments of the invention are
explained. These exemplary embodiments as well as the corresponding
drawings and subordinate claims show additional details of
advantageous embodiments of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is a perspective schematic representation of a
damping material with interspersed zones of increased fiber
interloping.
[0018] FIG. 2 is a schematic perspective principle representation
of a device for the production of a damping material in accordance
with FIG. 1.
[0019] FIG. 3 is a perspective principle representation of a
damping material with local condensed zones.
[0020] FIG. 4 is a perspective principle representation of a
modified embodiment of an inventive damping material with
strip-like condensed zones and interstices.
[0021] FIG. 5 is a perspective principle representation of another
exemplary embodiment of an inventive damping material consisting of
a multi-layer assembly and strip-shaped condensed zones.
[0022] FIG. 6 is a perspective principle representation of a
modified embodiment of a damping material consisting of a
multi-layer assembly.
[0023] FIG. 7 is a principle representation of a potential
production process for a damping material in accordance with the
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0024] FIG. 1 shows a random-fiber non-woven body 10 that consists
of an acoustic damping material 11 and, may be used, for example,
for sound absorption or for sound damping in rooms, in or on room
ceilings or walls, in loudspeaker boxes or other acoustic devices.
The random-fiber non-woven body 10 is represented here as a flat,
parallel-epipedal body. However, said body may also have a shape
that is suitable for the respective purpose of use. In the present
exemplary example, the random-fiber non-woven body 10 depicted as a
section of a preferably continuously produced mat 12, as shown in
FIG. 2.
[0025] The damping material 11 is made of an immeasurably large
number of individual fibers 13, 14, 15, 16 that, for example, may
consist of one uniform material or also of different materials. The
fibers 13 through 16, as well as the remaining fibers indicated in
FIG. 1, said fibers not being specifically referenced, may consist
in full or in part of glass, ceramic, wool, cellulose, synthetic
material, one or more elastomers, one or more polymers or the like.
The fibers may consist of only one of these materials. However, it
is also possible to have a homogeneous or inhomogeneous mixture of
fibers that consist of different such mentioned materials.
[0026] At least some of the fibers 13 through 16 may consist of a
metal or of a non-metallic material that may also be metallized.
The fibers 13 through 16 may have uniform diameters, cross-sections
and lengths or also different diameters and/or or different
cross-sections and/or different lengths.
[0027] The fibers 13 through 16 form a fiber web, wherein they are
positioned next to each other in a loose but cohesive arrangement.
In doing so, different zones may be distinguished in the
random-fiber non-woven body 10. The fibers 13, 14 are in a loose
zone 17 with minimal fiber interlooping, whereas the fibers 15, 16
are located in a compacted, more condensed zone 18 with an
increased degree of fiber interlooping. For example, the zone 17 is
formed by the afore-mentioned loose fiber web, whereas the zone 18
represents a compacted zone. Preferably, several zones with
increased fiber interlooping exist in the random-fiber non-woven
body 10, for example the zone 18, whereby these different zones may
be formed and/or arranged regularly or irregularly. They may extend
over the entire height of the fiber body 10 (vertically in FIG. 1)
or the mat 12.
[0028] In the zone 17, the fibers 13, 14 are predominantly arranged
in a plane that is essentially parallel to the upper side 19 or the
underside 20 of the random-fiber non-woven body 10, whereby the
fibers 13, 14 are preferably oriented essentially parallel and in
mat longitudinal direction 21, i.e., with respect to FIG. 2. The
fibers 13, 14, as well as any additional fibers oriented in mat
longitudinal direction have been joined, for example, in a combing
process, by carding a natural or synthetic fiber to produce a loose
non-woven web with parallelized fibers. In order to produce the
fiber body 10 in accordance with FIG. 1, the thusly obtained mat 12
is passed through a processing station 22, said station comprising
one or more members 23, 24 that act permanently or at selected
times on the mat 12 located or passing underneath, in order to
effect a local increased interlooping of the fibers such as, for
example the fibers 15, 16, and thus produce a zone 18 with
increased fiber interlooping, respectively. The members 23, 24 may
act on the mat 12 in a mechanical or non-mechanical manner. In
particular, considering synthetic fibers, said members may be heat
sources, radiation sources or also only members that dispense jets
of organic or inorganic fluids such as, for example, water.
Alternatively, the members 23, 24 may also comprise mechanical
tools such as felting needles or the like, these being used to
treat the mat 12.
[0029] For further explanation of the damping material 11 in
accordance with the invention, reference is made to FIG. 3. Again,
this damping material is initially a mat 12, wherein the fibers 13,
14 are largely parallelized in a loose fiber assembly or also
oriented in a crossed manner essentially parallel to the upper side
19. In the zone 18, said zone having been created, for example, by
local condensing of the mat 12 with water jets, the fibers 25, 26
have been reoriented out of the horizontal orientation into an
approximately perpendicular orientation relative to the upper side
19. Consequently, a greater degree of interlooping of the fibers
among each other occurs in the zones 18 than in the remaining zone
17. At the same time, this increased interlooping, as has been
created by water-jet condensing for example, is accompanied by a
compacting effect. FIGS. 3 and 4 show how, due to the treatment
process, the fibers have been locally reoriented in the zones 18
out of their normal orientation in their predominantly horizontal
position into an oblique or perpendicular position, whereby, at the
same time, the material has been condensed. The reorientation of
the fibers 25, 26 out of the horizontal direction (parallel to the
upper side 19) into the vertical direction, at the same time, means
a compacting of the fiber material at the affected location or in
the zone 18. The upper side 19 and/or the underside 20 may have
respectively one indentation in the condensed zone 18.
[0030] Inasmuch as the mat 12 is zone-wise condensed at certain
locations and not condensed at other locations, a varying density
structure is formed across the spatial segments. For example,
outside the condensed zones 18, it is possible for (hollow spaces)
interstices 27 displaying extremely low density, i.e., low
proportion of fibers per unit of volume, to form, the fiber density
in said interstices being lower than the density in the remaining
fiber web of the mat 12. Such interstices 27 may be irregular and
be approximately lentil-shaped, for example. Their form and
arrangement depend on the form and arrangement of the condensed
zones 18.
[0031] The random-fiber non-woven body 10 in accordance with FIG. 1
or FIG. 3 exhibits good sound damping properties. It also exhibits
a high pore and air volume. Sound waves impinging on the damping
material 11 penetrate the damping material 11 and are absorbed
there, i.e., ultimately converted into heat. This effect is
supported by the preferably irregular arrangement of the zones 18
that suppress the formation of standing waves and may achieve an
additional wave extinction in a large frequency spectrum due to
interference. Such interference may occur within the damping
material 11 as well as outside said damping material. As is shown
by FIG. 3, the condensed zones 18 may also be formed by
indentations that are preferably irregularly arranged on the
surface of the material, said indentations reflecting a certain
percentage of the impinging sound energy and, together,
contributing to the extinguishing interference.
[0032] The damping material 11 may be designed in various ways.
While the zones 18 in the embodiments described so far are formed
by local islands, for example having a rectangular, square,
circular or another contour, they may also be strip-shaped, as
shown by FIG. 4. The strips may have consistent or changing width.
The strips may have one uniform width or they may have different
widths.
[0033] The damping material 11 as in FIG. 4 has several zones 18,
28, 29 with increased fiber interlooping, three of these being
shown. These zones extend at a distance parallel to each other
along the transverse direction of the mat 12 (at a right angle to
the mat longitudinal direction 21) in FIG. 2 for example, or also
parallel to said mat longitudinal direction. Regarding the fiber
orientation for the zones 18, 28, 29, the comments that have been
made in conjunction with FIGS. 1 through 3 apply. Uncondensed zones
17, 30, 31 are formed between the zones 18, 28, 29, said
uncondensed zones preferably accounting for the greater part of the
volume of the damping material 11. In these zones, for example in
zone 29, again one or more interstices 27 may be formed. For
example, such an interstice 27 extends like a longitudinal channel
parallel to the adjacent condensed zones 18, 28.
[0034] In the damping material 11, the distances between the
parallel, strip-shaped condensed zones 18, 28, 29 has been selected
so as to be irregular. FIG. 4 illustrates three such distances L1,
L2, L3. Preferably, the distances are not equal. Ideally, none of
the distances L1, L2, L3, etc. is identical. The widths of the
zones 18, 28, 29 are preferably the same among each other.
[0035] The damping material 11 in accordance with FIG. 4 can be
produced in an apparatus in accordance with FIG. 2 in that a mat 12
of a non-woven fibrous material is passed through the processing
station 22. The fibers are loosely layered in predominantly
horizontal orientation and are stacked in a specific height h. The
width of the mat 12 is random. For practical purposes, these widths
are between 50 cm and 5 meters. Preferably, the mat 12 is obtained
by continuous production and can thus be adjusted as desired by
cutting.
[0036] FIG. 5 shows a damping material 11 representing a
multi-layer assembly. As illustrated, the material comprises two or
also more layers 32, 33, of which at least one, preferably however
more or all of them, have one or more condensed zones 34, 35, 36,
37. Considering the composition of the layer 32, all the
explanations provided regarding the exemplary embodiment of FIG. 4
apply. Likewise applicable to the layer 33 are the explanations
provided in conjunction with FIG. 4. Consequently, as explained in
conjunction with FIG. 4, the layers 32, 33 may be first provided
separately and then be superimposed. In doing so, the condensed
zones 34,35 of the upper layer 32 may be oriented parallel to the
condensed zones 36, 37 of the lower layer 33, whereby they,
preferably, need not be moved in a registered manner. As a result
of this, the distances of the condensed zones 34, 35 of the upper
layer 32 may be different from the distances between the condensed
zones 36, 37 of the lower layer 33. The layers 32, 33 may be
different regarding the number and position of the condensed zones
34 through 37.
[0037] As many such layers as are desired may be placed on each
other. If needed, layers without condensed zones may be interposed.
The cohesion of the layers 32, 33, as well as all potentially
additionally present layers can be created by continuously
condensed zones 38 that extend parallel to the other condensed
zones 34 through 37, or also in a direction transverse to them. The
continuous condensed zones 38 are preferably produced in that the
individual layers 32, 33 are placed on top of each other. For
example, they can be produced by condensing with water jets or by
any other mode of condensing as mentioned in this document.
Preferably, as illustrated, they are strip-shaped. However, it is
also possible to produce continuous condensed zones having a
locally limited contour, said contour being round, oval or
rectangular, for example. In the condensed zone 38, the fibers are
transferred from the upper layer 32 into the lower layer 33.
Additionally or alternatively, the fibers of the lower layer 33 may
have been transferred from the lower layer 33 into the upper layer
32. Again, as in all the other condensed zones, there is a greater
degree of interlooping of fibers in the condensed zone 38 than in
the surrounding material of the first zone 17. The condensing or
interlooping of fibers in the zone 38 may be the same as in the
zones 34 through 37. However, it is also possible to specify
different degrees of interlooping and condensing for the zones 34
through 37 and 38.
[0038] As a result of the number and arrangement of condensed zones
34 through 37 and 38 and their degree of condensation, as well as
the number of layers 32, 33, etc., it is possible to adjust the
damping properties of the damping material 11 within wide limits as
desired.
[0039] The damping material 11 in accordance with FIG. 5 may have
interstices--like the already described interstice 27--within the
layers 32, 33. In addition, interstices extending toward the
respectively other layer are formed on the condensed zones 34, 35
as well as 36, 37. FIG. 5 shows such an interstice 39 between the
condensed zone 35 and the layer 33. Such interstices can improve
sound-damping properties. The distances of the condensed zones 34,
35, 36, 37, 38 from each other, as well as the geometric distances
relative to the interstices 27, 39, are preferably within the range
of half the wavelength of the sound waves to be attenuated or a
multiple of half the wavelength. If, for example, in particular a
frequency of 200 Hz is to be attenuated, the distances may be in
the range of 85 cm. If the focus of the damping effect is to be at
2000 Hz, it is advantageous to specify the distances in the range
of 8.5 cm. A broader frequency spectrum can be covered by varying
these distances.
[0040] FIG. 6 shows another embodiment of the damping material 11
in accordance with the invention, said damping material having at
least two layers 32, 33. In this case, the layers 32, 33 are
oriented transversely with respect to each other. While the
condensed zones 36, 37 of the lower layer 33 extend in a first
direction, the condensed zones of the upper layer (zone 34) are
oriented transversely with respect thereto. The connecting
condensed zone 38 may extend parallel to the zone 34, transversely
with respect to the zones 36, 37, or in a separate different
direction. Due to the mutual crossing of both the condensed zones
34 and 36, as well as 37, additional interstices are formed in the
damping material 11, said interstices being capable of affecting
the sound-damping effect in a positive manner. In the layers 32,
33, the fibers in the uncondensed zones 17 may be oriented parallel
to each other or also crossed with respect to each other.
[0041] In each of the presented embodiments representing a
multi-layer assembly, the damping properties can be additionally
influenced in that the geometric configuration of the obtained
interstices and their relative distances are adjusted to the
frequency that is to be attenuated.
[0042] Furthermore, the damping properties can be adjusted in that
the layers 32, 33 and, optionally, additional layers are made of
different ground fiber materials, so that different mass densities
result in view of the spatial volume segment. In addition, it is
possible to vary the density of the non-woven fibrous web in a
direction transverse to the mat longitudinal direction 21.
[0043] FIG. 7 is a schematic illustration of the condensing process
by means of the water jet method. Again, the mat 12 has been
produced with a known method such as carding, optionally also by
cross-laying or by producing a spunbonded fabric. This mat 12 moves
in the direction of the mat longitudinal direction 21 under a
nozzle bar 49 of a water-jet condensing system, said nozzle bar
being known per se. The nozzle bar 49 may be part of one of the
members 23, 24 shown in FIG. 2. Again, the nozzle bar 49 comprises
at least one, preferably however more, nozzle clusters 40, 41, 42,
43 and, optionally, even more such nozzle clusters. Each of the
nozzle clusters 40 through 43 that are schematically symbolized by
circles in FIG. 7 may be individually formed by a group of smaller
nozzle orifices that are arranged linearly or in an array. The
distances between these nozzle clusters L1, L2, L3 are preferably
not identical to one another.
[0044] Each nozzle cluster 40 through 43 produces a bundle 44, 45,
46, 47 of water jets that impinge on the surface of the mat 12 and
penetrate the material of the mat. The impinging water jet bundles
44 through 47 cause a fluidizing of the fibers in the mat 12 and a
reorientation, as well as the interlooping of said fibers. This is
also accompanied by a condensing of the material of the mat 12 so
that, as the work progresses, the strip-shaped condensed zones 18,
34, 35, 36 are formed. The diameter of the nozzle clusters 40
through 43 and the pressure of the water that is applied above the
nozzle bar 49 are selected in such a manner that the water jet
bundles 44 through 47 fluidize said fibers but do not cause a
separation or even a destruction of the fibers. In doing so, it is
important that, between the individual water jet bundles 44 through
47, there be at least one interstice in which no condensing of the
mat 12 occurs so that here--in order to form zone 17--there is no
increased density of the non-woven fabric. A condensing of the mat
12 occurs only in the region of action of the water jet bundles 44
through 47. Furthermore, measures may be taken to temporarily
interrupt individual water jet bundles 44 through 47, for example
the water jet bundle 45. This may be accomplished by means of a
baffle that is pushed into the region of the water jet bundle 45 in
order to interrupt the latter. This means that, with a forward
movement of the mat 12 under the nozzle bar 49, a strip-shaped
condensed zone is created through the entire height of the mat,
said zone being interrupted in mat longitudinal direction 21.
[0045] The activation and deactivation of the condensing effect
cannot only be achieved by temporarily covering the individual
nozzle cluster 40 through 43 but also in that the entire nozzle
bar, for example of the members 23, 24, etc., is activated and
deactivated.
[0046] The method is suitable, in particular, for mats 12 of
polyester fibers. However, it is not restricted to a specific fiber
material. In addition, the manufacture of the damping material 11
is possible not only by water jet condensing but also by other
methods for locally condensing the mat 12. Methods using mechanical
needling or thermal condensing can be used. Essential is that zones
exhibiting varying spatial densities be produced in the damping
material 11 in a targeted manner.
[0047] A damping material 11 in accordance with the invention
consists of a ground material that is composed of fibers that are
in loose connection with each other. For example, the fibers are
minimally interlooped with each other or also glued to each other.
This ground material is condensed in some areas in that the fibers
are reoriented or interlooped with each other to a greater degree
or glued to each other. Consequently, zones 17 and 18 of different
densities are formed, thus making it possible to increase and
adjust, as desired, the sound-damping effect of the damping
material.
[0048] It will be appreciated that the above description of the
present invention is susceptible to various modifications, changes
and modifications, and the same are intended to be comprehended
within the meaning and range of equivalents of the appended
claims.
TABLE-US-00001 List of Reference Numerials: 10 Random-fiber
non-woven body 11 Damping material 12 Mat 13, 14, 15, 16, 25, 26
Fiber 17 Zone with minimal fiber interlooping 18 Zone with
increased fiber interlooping 19 Upper side 20 Underside 21 Mat
longitudinal direction 22 Processing station 23, 24 Member 27, 39
Interstice 28, 29, 34, 35, 36, 37 Linear zone with increased fiber
interlooping 30, 31 Linear zone with minimal fiber interlooping 32
Upper layer 33 Lower layer 38 Condensed zone traversing the layers
32, 33 40 First nozzle cluster 41 Second nozzle cluster 42 Third
nozzle cluster 43 Forth nozzle cluster 44 First water jet bundle 45
Second water jet bundle 46 Third water jet bundle 47 Fourth water
jet bundle 49 Nozzle bar
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