EP4200475A1 - Feutre de presse - Google Patents

Feutre de presse

Info

Publication number
EP4200475A1
EP4200475A1 EP21737656.5A EP21737656A EP4200475A1 EP 4200475 A1 EP4200475 A1 EP 4200475A1 EP 21737656 A EP21737656 A EP 21737656A EP 4200475 A1 EP4200475 A1 EP 4200475A1
Authority
EP
European Patent Office
Prior art keywords
threads
fabric layer
press felt
transverse
crossing points
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP21737656.5A
Other languages
German (de)
English (en)
Inventor
Robert EBERHARDT DR.
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Voith Patent GmbH
Original Assignee
Voith Patent GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Voith Patent GmbH filed Critical Voith Patent GmbH
Publication of EP4200475A1 publication Critical patent/EP4200475A1/fr
Pending legal-status Critical Current

Links

Classifications

    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
    • D21F7/00—Other details of machines for making continuous webs of paper
    • D21F7/08—Felts
    • D21F7/083—Multi-layer felts

Definitions

  • the invention relates to a press felt according to the preamble of claim 1
  • the load-bearing basic structure can have several layers of fabric that are arranged one above the other. Felts with such basic structures are described in EP 0 425 523 or EP 0 672 784 81, for example. Likewise, as described in EP2160495 B1, several layers of fleece fibers with different fiber counts can also be provided.
  • a press felt In operation, a press felt is subjected to repeated stresses in one or more press nips.
  • the felt is compressed in the press nip and, after passing through the press nip, the felt expands again essentially to its original thickness. Since this process is run through extremely frequently, the felt compacts after a short time.
  • the state of the art gives as an explanation for this a compression of the fleece layers.
  • the fabric layers are also compacted with the formation of a layer of reduced permeability. This changes important properties of the felt, such as permeability. In order to compensate for this, it is known, for example from EP2 678 472, to provide a particularly fine fleece layer which is abraded during operation of the felt.
  • the abrasion of the fine fleece fibers increases the permeability of the felt, while at the same time the permeability is reduced through compaction. Although this allows a largely constant permeability of the felt to be achieved, the provision of the "sacrificial fleece layer" is associated with additional costs and effort. It is therefore an object of the invention to propose a press felt in which the tendency to compact is reduced. It is also an object of the present invention to propose a felt that provides a large volume for absorbing liquid.
  • a press felt for a machine for producing a fibrous web comprising a woven base structure and a nonwoven overlay attached thereto, the base structure having a first fabric layer and a second fabric layer.
  • the first fabric layer has longitudinal threads and transverse threads crossing at crossing points, with the longitudinal threads and the transverse threads of the first fabric layer being welded to one another at at least 5% of the crossing points, in particular at at least 10% of the crossing points.
  • the inventor proposes that at least in the first fabric layer, parts of the longitudinal threads and transverse threads crossing at crossing points be welded together. It has proven to be advantageous if the longitudinal threads and the transverse threads of the first fabric layer are cohesively connected to one another, in particular welded to one another, at at least 5% of the crossing points, in particular at at least 10% of the crossing points. In this way, the displacement of the threads is prevented or made more difficult, and the compacting effect described above is suppressed.
  • the advantageous effect of the invention can be increased if the second fabric layer also has longitudinal threads and transverse threads crossing at crossing points, with the longitudinal threads and the transverse threads of the second fabric layer being bonded to one another at least 5% of the crossing points, in particular at least 10% of the crossing points. are in particular welded together. As a result, the mobility of the threads of the two layers relative to one another is reduced even further.
  • the basic structure has exactly two layers of fabric
  • embodiments can also be provided in which the basic structure also includes one or more additional layers, in particular one or more additional layers of fabric.
  • the material connection at the crossing points can be produced in various ways.
  • Bi-component fibers consist of two components, eg a core and a sheath.
  • the two polymers have different softening or melting temperatures.
  • the melting temperature of the core is higher than that of the sheath , so that the sheath can be melted at a certain temperature impact, thus creating connection points between the respective core fibers in the mixture of the present matrix.
  • NIR transmission welding is considered to be particularly advantageous.
  • the commonly used threads made of polyamide are largely transparent to light from the NIR range between approx. 780 nm and 1100 nm.
  • the longitudinal threads and/or the transverse threads of the first layer and/or the second layer absorb laser light of a wavelength completely or to a significant extent that lies in the range between 780 nm and 1100 nm. (An absorption of more than 30%, in particular more than 40% of the corresponding light is regarded as significant absorption. Such threads are referred to below as absorbing threads).
  • the tissue is suitably irradiated with light from this wavelength range, the light penetrates relatively unhindered through the non-absorbent threads and is absorbed by the absorbent threads. As a result, the contact point between the two threads heats up to such an extent that welding takes place.
  • the absorbent threads can consist of the same polymer as the other threads, to which an additional absorber additive has been added.
  • an additional absorber additive has been added.
  • compatible polymers can be used instead of the same polymer, e.g. Polyamide 6 and Polyamide 6.6.
  • quasi-simultaneous welding processes can also be used to create spot welds.
  • the use of absorbers can sometimes be dispensed with.
  • this selective irradiation takes place in the form of a regular pattern, e.g. in the form of straight lines, wavy lines, dot patterns, etc.
  • the width of these lines or the diameter of the dots can be chosen so large that several crossing points, in particular 2, 3, 4, 5 or more are covered.
  • crossing points with the material-locking connections are not exclusively in a partial area of the covering—for example a seam area—but are distributed over the entire surface of the covering, in particular evenly.
  • Such a uniform distribution can be achieved, for example, in that absorbent threads are woven in as CD threads or as MD threads according to a fixed, predetermined pattern. For example, it can be provided that every 10th CD thread is an absorbent thread. This leads to a rather low number of connection points. If every 4th CD thread, every 2nd CD thread or even every CD thread is woven in as an absorbent thread, the number of possible connection points increases.
  • BiCo threads can also be woven in according to the pattern described above.
  • the fabrics can be flat woven.
  • the fabrics can be treated in a roll to roll process.
  • a fabric with the material connections can be produced as rolled goods and then cut to size accordingly during the production of the actual felt.
  • the fabrics can be flat-woven and welded into an endless band.
  • the fabrics can be endlessly woven.
  • the fabrics can have a seam connection, preferably with a pin-seam.
  • the fabrics can be single-layer or multi-layer.
  • the fabrics can be woven from monofilaments and/or multifilaments and/or threads.
  • the fabrics can also be leno fabrics.
  • Neighboring crossing points are understood to mean the four crossing points that are directly adjacent in the longitudinal and transverse direction.
  • Such an arrangement of the materially bonded connections, in particular the welded joints, is advantageous because this allows the threads to be fixed well, but even with a comparatively high proportion of materially bonded crossing points (e.g. 30%, 40% or 50%) the increase in Stiffness of the structure still remains tolerable.
  • Such a fabric layer is also easy to produce.
  • a fabric that is produced in a plain weave can be used as the first fabric layer.
  • Longitudinal threads can be used for the fabric, which are transparent to the light of a specific wavelength, while the transverse threads completely or partially absorb this wavelength.
  • the integral connections can then be realized as welded connections by means of transmission welding with light of this wavelength.
  • the tissue is irradiated from one side with light of this wavelength, e.g. with a laser, there are crossing points where the transparent thread lies over the absorbing thread. At these crossing points, the light penetrates through the transparent thread and is absorbed by the absorbing thread, resulting in heating at the contact point and a material connection.
  • this wavelength e.g. with a laser
  • the absorbent thread lies above the transparent one at the four adjacent crossing points. Therefore, the absorbent thread only heats up on its upper side, but not at the point of contact. There is therefore no materially bonded connection at these crossing points.
  • FIG. 1 fabric layer for a press felt according to one aspect of the invention
  • Figures 2a, 2b, 2c show the process of compaction, which is suppressed by an embodiment according to the present invention.
  • Figure 3 shows a press felt according to one aspect of the invention
  • FIG. 1 shows a fabric layer that can be used as a first fabric layer 1 or a second fabric layer 2 in a press felt according to one aspect of the invention. Shown is a plain weave fabric made of crossing longitudinal threads 3 and transverse threads 4 . Some of the transverse threads 6 are designed as absorbent threads 6 . In the example shown in FIG. 1, every second transverse thread 4 is designed as an absorbent thread 6 .
  • the other threads 3, 4 are made of a material such as a polyamide, which is completely or largely transparent to light in the NIR range.
  • the absorbent threads 6 can consist, for example, of the same polymer to which an absorber additive has been added.
  • crossing points 5 are irradiated with light from a wavelength range that the absorbing threads 6 absorb - for example by means of a corresponding NIR laser - this penetrates through the non-absorbing longitudinal threads 3 to the absorbing threads 6. These heat up primarily at the contact point of the both threads, which leads to a material connection of the two threads in the form of a welded joint. Either all of these crossing points 5 can be welded, or only some of them.
  • the absorbent thread 6 runs above the longitudinal thread 3 at some of the crossing points in FIG. If you also want to create a material connection at these crossing points, it is advantageous to irradiate the fabric from the opposite side.
  • the fabric shown in Figure 1 also results in an embodiment in which at each crossing point 5, at which the longitudinal threads 3 and the transverse threads 4 are materially bonded to one another, there is no material bond at the adjacent crossing points 5 consists.
  • FIGS. 2a, 2b and 2c schematically show the behavior of a press felt under load, in which none of the fabric layers 1, 2 have crossing points 5 connected to one another with a material bond.
  • the press felt has a first fabric layer 1 and a second fabric layer 2, which together provide the basic structure of the felt.
  • a fleece overlay 7 is provided on the first fabric layer 1 .
  • the first fabric layer 1 and the second fabric layer 2 are different, which is shown here as an example by different diameters of the longitudinal threads 3.1 of the first layer 1 and the longitudinal threads 3.2 of the second layer 2.
  • the two layers 1, 2 can also be of the same type of fabric; B.
  • FIG. 2a shows the felt without an external load.
  • a load acts on the felt when passing through a press nip, for example.
  • the second fabric layer 2 is thereby pressed upwards against the first fabric layer. This results in shearing forces in the transverse direction on the longitudinal threads 3.1, 3.2, favored by a round shape of the threads.
  • Figure 2c then shows the felt in compressed form.
  • the fleece overlay 7 is compressed by the external load.
  • the longitudinal threads 3.1, 3.2 also shift in the transverse direction, so that the two fabric layers 1, 2 are partially pressed into one another.
  • the "void volume" of a fabric layer 1, 2 is thus partially filled by the threads of the other fabric layer 2, 1 and is no longer available for liquid absorption.
  • FIG. 3 differs from FIG. 2c only in that the felt is constructed according to one aspect of the present invention.
  • the longitudinal threads 3.1 and the transverse threads 4 of the first fabric layer 1 are cohesively connected to one another, in particular welded to one another, in particular at at least 5% of the crossing points 5, in particular at at least 10% of the crossing points 5.
  • the crossing points 5, in particular at least 10% of the crossing points 5, the longitudinal threads 3.2 and the transverse threads 4 of the second fabric layer 2 are cohesively connected to one another, in particular welded to one another.
  • the non-woven layer 7 is compressed.
  • the longitudinal threads 3.1, 3.2 cannot deviate in the transverse direction.
  • the transverse forces are absorbed by the materially bonded connections at the crossing points 5 . This prevents or at least reduces penetration of the first fabric layer 1 and the second fabric layer 2 .
  • the void volume of the fabric layers 1, 2 is hardly reduced by penetrating threads 3, 4 of the other fabric layer 2, 1, and is therefore still available for liquid absorption.

Landscapes

  • Nonwoven Fabrics (AREA)
  • Paper (AREA)

Abstract

L'invention concerne un feutre de presse pour une machine de fabrication d'une bande de matière fibreuse, comprenant une structure de base tissée et un support non tissé fixé sur cette dernière, la structure de base comprenant une première couche de tissu et une seconde couche de tissu, au moins la première couche de tissu présentant des fils longitudinaux et des fils transversaux qui se croisent au niveau de points d'intersection, les fils longitudinaux et les fils transversaux de la première couche de tissu étant liés d'un seul tenant les uns aux autres, en particulier soudés les uns aux autres, à au moins 5 % des points d'intersection, en particulier à au moins 10 % des points d'intersection.
EP21737656.5A 2020-08-18 2021-06-30 Feutre de presse Pending EP4200475A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102020121627.0A DE102020121627A1 (de) 2020-08-18 2020-08-18 Pressfilz
PCT/EP2021/067968 WO2022037832A1 (fr) 2020-08-18 2021-06-30 Feutre de presse

Publications (1)

Publication Number Publication Date
EP4200475A1 true EP4200475A1 (fr) 2023-06-28

Family

ID=76796995

Family Applications (1)

Application Number Title Priority Date Filing Date
EP21737656.5A Pending EP4200475A1 (fr) 2020-08-18 2021-06-30 Feutre de presse

Country Status (5)

Country Link
US (1) US20240026607A1 (fr)
EP (1) EP4200475A1 (fr)
CN (1) CN115885072A (fr)
DE (1) DE102020121627A1 (fr)
WO (1) WO2022037832A1 (fr)

Family Cites Families (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB8814436D0 (en) 1988-06-17 1988-07-20 Scapa Group Plc Papermachine clothing
DE4404507A1 (de) 1994-02-12 1995-08-17 F & W Tech Faeden Gmbh Pressenfilz für die Papierindustrie
GB2287257A (en) 1994-03-10 1995-09-13 Scapa Group Plc Papermakers marking felt
US5549967A (en) 1995-05-04 1996-08-27 Huyck Licensco, Inc. Papermakers' press fabric with increased contact area
US5888915A (en) 1996-09-17 1999-03-30 Albany International Corp. Paper machine clothings constructed of interconnected bicomponent fibers
ES2262726T3 (es) * 2002-04-25 2006-12-01 THOMAS JOSEF HEIMBACH GESELLSCHAFT MIT BESCHRANKTER HAFTUNG & CO. Revestimiento de maquina papelera y procedimiento para su fabricacion.
US7455752B2 (en) 2004-07-22 2008-11-25 Albany International Corp. Semi-permeable fabrics for transfer belt and press fabric applications
DE102007028365A1 (de) 2007-06-15 2008-12-18 Voith Patent Gmbh Pressfilz
CN101848801B (zh) 2007-09-05 2014-08-20 阿尔巴尼国际公司 造纸机和工业织物接缝的制造方法和由该方法制造的接缝
DE102011004568A1 (de) 2011-02-23 2012-08-23 Voith Patent Gmbh Pressenpartie einer Maschine zur Herstellung einer Faserstoffbahn
DE102012207016A1 (de) 2012-04-27 2013-10-31 Voith Patent Gmbh Stabilisierte Webnaht für flachgewebte Endlosgewebebänder
DE202019102306U1 (de) * 2019-04-24 2019-07-25 Heimbach Gmbh Pressfilz mit einem Fadengelege und einem auf der Maschinenseite oder der Papierseite des Fadengeleges vorgesehenen Trägervlies

Also Published As

Publication number Publication date
WO2022037832A1 (fr) 2022-02-24
US20240026607A1 (en) 2024-01-25
CN115885072A (zh) 2023-03-31
DE102020121627A1 (de) 2022-02-24

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