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EP4638862A1 - Structure de base et revêtement - Google Patents

Structure de base et revêtement

Info

Publication number
EP4638862A1
EP4638862A1 EP23833674.7A EP23833674A EP4638862A1 EP 4638862 A1 EP4638862 A1 EP 4638862A1 EP 23833674 A EP23833674 A EP 23833674A EP 4638862 A1 EP4638862 A1 EP 4638862A1
Authority
EP
European Patent Office
Prior art keywords
threads
fabric layer
basic structure
fabric
structure according
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
EP23833674.7A
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 EP4638862A1 publication Critical patent/EP4638862A1/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 basic structure for a covering according to the preamble of claim 1 and to a covering using such a basic structure.
  • the basic structure In many applications it is desirable for the basic structure to have properties - for example in terms of its storage volume - that cannot easily be achieved with a single layer of fabric. In these cases the basic structures are made from several fabrics that are arranged one on top of the other.
  • Round fabrics and flat fabrics have their specific advantages and disadvantages when used in basic structures.
  • Round fabrics have a high tensile strength and are very uniform due to the lack of seams or joints.
  • their production is very complex due to the more complicated weaving process.
  • the exact length of the subsequent covering must already be known during the weaving process.
  • Flat fabrics can be manufactured very quickly and inexpensively. They can also be manufactured as rolls, which are then cut to size to suit the required covering.
  • the joints naturally represent potential weak points, which can become visible as markings in the fibrous web.
  • the object of the invention is to further improve the known multi-layer coverings.
  • Proposed is a basic structure for a covering, in particular a press felt for a machine for producing a fibrous web, comprising a first fabric layer with first MD threads and first CD threads and a second fabric layer with second MD threads and second CD threads, wherein the first fabric layer is arranged above the second fabric layer.
  • the first CD threads have a smaller diameter than the second CD threads and the thread density of the first CD threads is higher than the thread density of the second CD threads.
  • a fabric layer is referred to as being "above” another fabric layer if, when used as intended, it is positioned closer to the paper-contacting top side of the covering. It is particularly possible that this fabric layer is positioned "directly above” the other fabric layer and that the two fabric layers touch each other completely or partially. Alternatively, it can also be provided that other components of the basic structure, e.g. fleece layers, films or other fabric layers, etc. are positioned between the two fabric layers. For CD threads with a circular cross-section, their diameter can be clearly determined as a circle diameter.
  • fictitious diameter For CD threads that do not have a circular cross-section and when using twisted CD threads, a "fictitious diameter" is to be used as the diameter in this application.
  • This fictitious diameter corresponds to the diameter of a circle that has the same area as the cross-sectional area of the thread, or the sum of the cross-sectional areas of the filaments of the thread.
  • the first fabric layer and the second fabric layer are not woven together.
  • the two fabric layers are then not layers of a multi-layer fabric, but form a laminate of two largely independent layers. This is very advantageous for basic structures according to aspects of the present invention, among other things, because it allows both the Both the diameter and the thread density of the two layers can be varied independently of each other and adapted to requirements.
  • the thread density is defined as the number of threads per unit length.
  • the diameter of the first CD threads is a maximum of 90% of the diameter of the second CD threads.
  • the thread density of the first CD threads is at least 3%, in particular at least 5% or at least 10%, in particular at least 15%, preferably at least 20% higher than the thread density of the second CD threads.
  • the thread density of the first CD threads is a maximum of 80%, in particular a maximum of 60% higher than the thread density of the second CD threads.
  • Another advantage of the different thread density of the two layers is that it can suppress the moiré effect. If the difference is less than 3%, the moiré effect is often not sufficiently suppressed.
  • the thread density of the first CD threads can be between 20 and 200 threads/10cm, preferably between 50 and 100 threads/10cm.
  • the CD threads of the basic structure are the warp threads of the loom. Since changing the warp system is very complex and results in the loom being down for a long time, a short-term change to the CD threads in circular fabrics is hardly possible.
  • the smaller diameter of the CD threads and the higher thread density in the first layer lead to an increase in the number of contact points, a finer structure and a lower roughness.
  • the basic structure does not have any further fabric layers above the first fabric layer.
  • the use of coarser CD threads and reduced thread density leads to a more open structure and enables a fabric construction with increased permeability towards the running side, which in particular enables felts with improved dewatering performance.
  • the structures that are more open towards the running side can reduce the tendency to become dirty.
  • the wear properties of the basic structure can also be improved by using coarser CD threads in the second fabric layer.
  • a further advantage of basic structures according to aspects of the invention is that the anchoring of nonwoven fibers is improved compared to identical fabric layers.
  • both the first fabric layer and the second fabric layer can be made of round fabric.
  • this is quite complex because, as described, different warp systems have to be used.
  • the invention is particularly advantageous if the first fabric layer and/or the second fabric layer comprises or consists of a flat fabric.
  • Hybrid basic structure One fabric layer is a round fabric, the other
  • Fabric layer consists of a flat weave. Since the CD threads of the round weave are difficult to change, the ratio of the thread diameters and thread densities is conveniently adjusted via the flat weave.
  • the hybrid structure can be designed in such a way that the first fabric layer is designed as a round fabric, whereby the connection point of the front edges is shielded from the paper side by the round fabric. This can be advantageous if the type of paper to be produced is very susceptible to these seam markings.
  • the hybrid structure can also be designed in such a way that the first fabric layer is designed as a flat fabric.
  • Both the first fabric layer and the second fabric layer made from a separate flat fabric, which is made endless by connecting the front edges.
  • a single flat fabric is folded and laid on top of one another to form a two-layer structure that has seam loops at the two folds.
  • the first fabric layer and the second fabric layer are part of a single flat fabric in this basic structure.
  • the two fabric layers are connected to one another at the folds, but they are not woven together in the sense of this application.
  • WO21028116 A1 shows a further development of this technology in which the basic structure does not consist of a single piece of flat fabric, but of several flat fabrics arranged one behind the other, two of which are designed as loop elements.
  • different threads are used for the first CD threads and/or the second CD threads.
  • CD threads with different diameters can be used.
  • both filaments and twisted yarns are used as first CD threads in the first fabric layer and/or as second CD threads in the second fabric layer.
  • These can also be be arranged alternately, so that twisted yarn-filament-twisted yarn-filament are always arranged alternately.
  • Different ratios of twisted yarns to monofilaments can be provided, such as 3:1, 2:1, 3:2, 1:1, 2:3, 1:2 or 1:3. It has been shown that such an alternating arrangement of filaments and twisted yarns, especially in the first fabric layer, can significantly improve the fiber anchoring of nonwoven fibers.
  • first and second layers have the same ratio of twisted yarn and monofilaments, for example 2:1.
  • the MD threads of the two fabric layers can also be designed as twisted yarns; however, it is often advantageous if all MD threads of the two fabric layers are designed as filaments.
  • the MD threads of the first fabric layer and/or the second fabric layer can in particular have a diameter between 0.2 mm and 1 mm
  • the MD thread density of the first fabric layer and/or the second fabric layer can be between 20 and 200 threads per 10 cm.
  • first fabric layer and the second fabric layer have the same MD threads or at least the MD threads which have essentially the same thread cross-section.
  • the diameter of the MD threads of the first fabric layer and/or the second fabric layer is between 0.24 mm and 0.6 mm, preferably between 0.3 mm and 0.5 mm.
  • a two-layer base structure has the advantage that the MD threads of both layers help to absorb tensile forces in the MD direction.
  • the MD threads of the individual layers can be kept thinner and in particular can have diameters of 0.6 mm, 0.5 mm or less.
  • the base structure becomes more rigid with MD threads with diameters over 0.6 mm, which makes handling the structure more difficult during further processing, e.g. into felt, and during later use.
  • Seam structure it can also be advantageous not to choose a thread diameter that is too thin for the MD threads, as it is difficult to form the seam loops and later insert a pin wire if the MD threads are too thin.
  • first fabric layer and the second fabric layer have different MD threads.
  • the diameter of the first CD threads is approximately 78% of the diameter of the second CD threads (0.35/0.45 *100 ⁇ 77.8)
  • the CD thread density of the first fabric layer is approximately 23% greater than the CD thread density of the second fabric layer (85/69 ⁇ 1.23).
  • both the first CD threads and the second CD threads are made as twisted yarns.
  • the diameter of a thread should be determined via the cross-sectional area of the individual filaments:
  • a filament with a diameter of 0.2 mm has a cross-sectional area of approximately 0.03142 mm 2 .
  • the fictitious diameter of the second CD thread is 0.4 mm
  • the (fictitious) diameter of the first CD threads is approximately 86.6% of the (fictitious) diameter of the second CD threads.
  • the system of the first CD threads consists of different threads. There is both a 0.35 mm filament and a 0.2 mmx3 thread, which are woven alternately, for example. Since the fictitious diameter of the second CD threads is 0.4 mm as shown, the (fictitious/real) diameters of all first CD threads (0.35 mm and 0.346 mm) are smaller than the fictitious diameter of the second CD threads. Furthermore, the invention relates to a covering, in particular a press felt for a machine for producing a fibrous web, wherein the covering has a basic structure according to one of the aspects of the invention.
  • the covering can also be a seam felt.
  • one or more layers of nonwoven fibers are usually arranged on the top of the covering - and if necessary also on the bottom of the covering - and are attached by needling.

Landscapes

  • Paper (AREA)

Abstract

L'invention concerne une structure de base pour un revêtement, en particulier un feutre de presse pour une machine de production d'une bande de fibres, comprenant un premier pli avec des premiers fils (MD) et des premiers fils (CD) et un second pli avec des seconds fils (MD) et des seconds fils (CD), le premier pli étant disposé au-dessus du second pli. Les premiers fils (CD) ont un diamètre inférieur à celui des seconds fils (CD) et l'épaisseur des premiers fils (CD) est supérieure à celle des seconds fils (CD).
EP23833674.7A 2022-12-21 2023-12-15 Structure de base et revêtement Pending EP4638862A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102022134296 2022-12-21
PCT/EP2023/086017 WO2024132910A1 (fr) 2022-12-21 2023-12-15 Structure de base et revêtement

Publications (1)

Publication Number Publication Date
EP4638862A1 true EP4638862A1 (fr) 2025-10-29

Family

ID=89452431

Family Applications (1)

Application Number Title Priority Date Filing Date
EP23833674.7A Pending EP4638862A1 (fr) 2022-12-21 2023-12-15 Structure de base et revêtement

Country Status (3)

Country Link
US (1) US20250320660A1 (fr)
EP (1) EP4638862A1 (fr)
WO (1) WO2024132910A1 (fr)

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ES2121023T3 (es) * 1991-11-21 1998-11-16 Weavexx Corp Fieltros multicapas.
US7892402B2 (en) 2007-10-05 2011-02-22 Albany International Corp. Flat woven full width on-machine-seamable fabric
KR102470981B1 (ko) * 2018-02-12 2022-11-25 휴익 라이센스코, 인코포레이티드 보조 하단 md 얀을 갖는 다층 제지용 성형 직물
DE102019121485B3 (de) 2019-08-09 2020-08-06 Voith Patent Gmbh Bespannung
JP7526939B2 (ja) 2020-08-26 2024-08-02 イチカワ株式会社 抄紙用フェルトおよびその製造方法

Also Published As

Publication number Publication date
US20250320660A1 (en) 2025-10-16
WO2024132910A1 (fr) 2024-06-27

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