FI64410C - ELASTISK FILT ELLER VIRA FOER EN PRESS I EN PAPPERSMASKIN - Google Patents

Description

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Patent · OCh registerstyrelsen Ant6kan utlsgd och utl.slcrlften publlcerad cya [.oj (32) (33) (31) Requested privilege — Begird prlorltet (71) Tampereen Verkatehdas Oy, PI U27, 33101 Tampere 10, Suomi-Finland (FI) ( 72) Axel Cedercreutz, Tampere, Kristian Lundström, Pirkkala, Finland -Finland (FI) (7 * 0 Oy Kolster Ab (5 * 0 Elastic felt or wire for a paper machine press -Elastic filter or wire for press and en papersmask is an elastic felt or wire for a press of a paper machine, which felt or wire is made of monofilament or multifilament or staple fibers and at least partially contains elastic filaments or fibers.

In a paper machine, a wet web is transferred with a felt from a wire section to a press, which may be several in succession. In the press, both the web and the felt are pressed simultaneously between the rollers, whereby the water in the web can be mechanically removed through the felt below. Today, paper machines have 2 or 3 wet presses to make a wet paper web pressed to 30-40% dry matter.

The high speeds of modern paper machines and the high line pressures of presses place high demands on the elasticity of press felts. The felt must be able to withstand large momentary loads and return to its original shape. The elastic property of the felt is also important for its opening. The flexible structure of the felt or wire reduces the adhesion of paper fillers to the felt or wire.

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With current felt fabrication techniques, a gauze layer is needled on one or both sides of the felt base fabric to provide the flexible structure required by the press. In practice, this gauze layer receives load variations when the base fabric can be considered inelastic in wire-based felts, while compressible base fabrics are considered flexible.

In its current form, the fluffy press felt is inherently poorly able to meet the requirements imposed on it in modern presses, where the line pressure can be as high as 120 kN / m. In use, the fluff layer of the felt rapidly loses its bulkiness and flexibility as the fibers become tired under repeated compression. Fluff wear is significant with current press felts as service life increases. These factors substantially reduce the elasticity of the felt as its service life increases and at the same time the water permeability of the felt also decreases. The annoying vibration that sometimes occurs with presses is also much more common with used felt than with new one due to the reduced flexibility of the newly worn and flattened fluff layer.

Finnish patent publication 59 836 discloses a blanket in which the elasticity of the felt is obtained by mixing an elastomeric substance which is elastic in the longitudinal direction and which does not require transverse bonds between the yarns or fibers of the felt. However, the longitudinally elastic elastomers are very weak in the transverse direction. If such elastomers are stretched transversely, the molecular chains become detached from each other and the elastomer degrades and is no longer able to return to its original shape.

It is also known in the past to use fibers in the manufacture of felts with a single central, longitudinal, continuous cavity that makes the fiber nearly tubular. However, the tubular fiber results in excessive compressibility and other disadvantages in the paper machine felt.

The object of the present invention is to provide an elastic press felt or wire which eliminates the above-mentioned drawbacks and which retains its elasticity with the service life. This object is achieved by a felt or wire according to the invention, which is characterized in that the filaments or fibers have channels closed from the cavity or the like which make the filaments elastic in the transverse direction.

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The invention is based on the idea that the elasticity of a felt or wire is provided by filaments or fibers which are themselves elastic in the transverse direction. By making a felt or wire from such intrinsically elastic filaments, yarns or fibers, the elasticity and retention of elasticity of the felt is substantially improved. The filaments or fibers may have one or more channels in their longitudinal and / or transverse direction, or there may be air or gas bubbles inside the filaments or fibers in the longitudinal and / or transverse direction. The filament or fiber may have a round, oval or other shape. The channels or cavities are so small that the fiber retains its massive character and does not become tubular despite the channels. In the transverse direction alone, the elastic felt does not lose its bulk in compression to such an extent that its water absorption capacity is significantly affected.

When a felt or wire retains its elasticity, its cleanability is improved and its service life is extended on a paper machine. The channels or cavities in the filament or fiber make it more resilient than other fibers, allowing dirt to effectively detach from the surface of the filament or fiber due to its deformation. The elastic felt is better able to maintain the required permeability even in longer use.

Due to its elastic structure, a felt or wire made of elastic filaments or fibers is very efficient at receiving and damping the vibration energy applied to it. This is of considerable importance in preventing harmful vibrations in the presses.

The invention will be described in more detail below with reference to the accompanying drawing, in which Fig. 1 shows a first embodiment of a felt according to the invention in cross-section, Fig. 2 shows a larger detail of a felt, Fig. 3 shows a second embodiment of a felt according to the invention in cross-section, a third embodiment of a felt according to the invention, Fig. 6 shows a detail of a felt in a larger size, Fig. 7 shows an embodiment of a wire according to the invention, and Fig. 4 64410 shows a detail of a wire in a larger size.

Figures 1 and 2 of the drawing show a press felt 1, which essentially comprises a base fabric 2, a first gauze layer 3 needled on one side thereof and a second gauze layer 4 needled on the opposite side of the base fabric.

The base fabric is woven from yarns, which may be single or multiple monofilament yarns, multifilament yarns, or staple fiber yarns using polyamide, polyester, polypropylene, polyacrylic, or other synthetic material as a raw material. In this application example, monofilament yarns having a plurality of channels 6 in the longitudinal direction of the filament are used as the longitudinal yarns 5. Such filaments are manufactured e.g. U.S. trade name DuPont under the trademark "ANTRON III HF" for other purposes. Ordinary spun yarn is used as the transverse yarns 7 of the base fabric. The bonding of the base fabric in this case is simple, but can also be multilayered.

The gauze layers 3, 4 are made of ordinary fibers 8.

It is noted that the filament yarns 5 are elastic in the transverse direction of the filament due to the channels therein and that the whole felt is given a structure which is flexible in a direction perpendicular to the surface of the felt due to these elastic filaments. Alternatively, en may be included in the gauze layers 3, 4. 5 types of elastic fibers of filaments.

Figures 3 and 4 show a press felt 11 comprising essentially a base fabric 12, a first fluff layer 13 needled on one side thereof and a second fluff layer 14 needled on the opposite side of the base fabric.

The base fabric is woven from yarns, of which the longitudinal yarns 15 are ordinary monofilament yarns and the transverse yarns 17 are spun from synthetic fibers with gas bubbles 16 in the longitudinal direction of the fiber.

The fluff layers 13, 14 consist of ordinary fibers 18, in which case such gas bubble-containing elastic fibers 19 are added to the fibers of the layer 13. The elastic fibers can have a fineness of 1 to 120 denier.

Alternatively, one or both of the fluff layers may be composed entirely of these elastic fibers, or a suitably thick layer of such elastic fibers may be placed on or inside the fluff layer in the ordinary fluff.

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The press felt 21 shown in Figures 5 and 6 essentially comprises a base fabric 22, a fluff layer 23 needled on one side thereof and a fluff layer 24 needled on the other side of the base fabric.

The base fabric 22 is similar to the base fabric 2 described in connection with Figure 1. The fluff layer 23 consists of a surface layer 23a containing fibers 29 having microscopically small transverse channels 26 of the fiber extending to the surface of the fiber. The inner layer 23b of the fluff layer 23 consists of ordinary fibers 28 as well as the second fluff layer 24. The transverse channels make the fibers 29 elastic and in addition to the resilient structure of the felt, a capillary effect is provided on the felt, which increases the felt's water absorption capacity. These types of elastic fibers are manufactured by the West German company name Bayer AG.

In the drying wire according to the invention, elastic filaments of the type described above are used as longitudinal and / or transverse yarns throughout or in combination with ordinary filaments in substantially the same manner as described above in connection with the base fabrics of press felts.

The drying wire 31 shown in Figures 7 and 8 comprises longitudinal yarns 35 and transverse yarns 37. The longitudinal yarns are formed by monofilaments with longitudinal channels 36. The transverse yarns are ordinary solid monofilament yarns.

The drawing and the related explanation are only intended to illustrate the idea of the invention. The details of the felt or wire according to the invention can vary considerably within the scope of the claims. The press felt can also be realized as a nonwoven-type felt without a base fabric. The elastic filaments and fibers may be made elastic by means of a suitable cross-sectional shape, e.g. an open-ring shape or the like. Elasticity can also be provided by surface grooves or similar open shapes.

Claims (13)

An elastic blanket or wire for a press in a paper machine, said blanket (1; 11; 21) or wire (31) made of mono or multifilament or cut fibers and at least partially containing elastic filaments (5; 17; 35) or fibers (19; 29), characterized in that the filaments (5; 17; 35) or the fibers (19; 29) have such channels (6; 26; 36), closed seals (16) or the like, which do the filaments are elastic in the transverse direction. 2. A felt or wrap according to claim 1, characterized in that the channels (6; 36) are longitudinal. Felt or wrap according to claim 1, characterized in that the channels (26) are transverse. Felt or wrap according to claim 1, characterized in that the closed hollows (16) are located in the filaments (17) or the fibers in their longitudinal and / or transverse direction. Felt or wrap according to claim 4, characterized in that the hollows (16) are formed by air or gas bubbles. A felt according to any of the preceding claims with a bottom fabric (2), which is nested at least on one side a floral layer (3), characterized in that the elastic filaments (5) extending longitudinally and / or transversely are woven into the bottom fabric (2). Felt according to any of claims 1-5 with a bottom fabric (12; 22) on which is knitted at least on one side a wadding layer (13; 23), characterized in that the elastic fibers (19; 29) are located in the transverse direction. in wadding layer (13; 23). Felt according to claim 7, characterized in that the pad (23) has a layer (23a) which consists of elastically fibers (29) in the transverse direction, while the other pad (23b) consists of ordinary fibers (28). 9. A felt according to claim 8, characterized in that the layer (23a) consisting of elastic fibers (29) is located on one surface of the pad (23). Felt according to any of claims 7-9, characterized in that the transversely elastic filaments (17; 25) are woven into the bottom fabric (12; 22).