Fabric and method for producing same

Abstract

A fabric, in particular a press felt, is provided for use in a press section of a machine for producing a fiber web such as a paper, cardboard, or tissue web. The fabric is formed of multiple strips which are arranged adjacent one another and extend substantially parallel to one another in a machine direction. The strips together form a width of the fabric in the machine transverse direction. Each strip is designed as a double-layered sheet material. Strips arranged adjacently in respective pairs are connected by way of a connecting strip. A part of the width of each of the connecting strips extends in the machine transverse direction into the two adjacent strips. The strips are connected to the connecting strips.

Claims

1. A fabric, comprising: a plurality of strips disposed beside one another and extending substantially parallel to one another in a machine direction; said strips together forming a width of the fabric in a machine transverse direction; each said strip being formed as a double-layer sheet material; connecting strips connecting mutually adjacent strips that are arranged beside one another in pairs to one another; a part of a width of each of said connecting strips extending in the machine transverse direction into the two adjacent said strips; wherein said strips are connected to said connecting strips, and said connecting strips are inserted between layers of said double-layer strips.

2. The fabric according to claim 1, wherein the part of the width of each connecting strip in the machine transverse direction by which each of said connecting strips extends into the two adjacent strips is at least 5% of the width thereof.

3. The fabric according to claim 1, wherein said sheet material is selected from the group consisting of woven fabrics, laid fabrics, knitted fabrics, crocheted fabrics, spiral structure, tapes, and films.

4. The fabric according to claim 1, wherein said sheet material has a width of 30 to 600 cm in the machine transverse direction.

5. The fabric according to claim 1, wherein end edges of said double-layer sheet materials are connected to one another, rendering the double-layer sheet materials endless, forming a tube-like material.

6. The fabric according to claim 5, wherein the end edges are connected by a process selected from the group consisting of ultrasonic welding, laser welding, high-frequency welding, thermal welding, thermal welding with a monofilament, adhesive bonding, gluing with hot melt adhesives, filling with a resin and needling.

7. The fabric according to claim 1, wherein said connecting strips have the same width as said strips in the machine transverse direction.

8. The fabric according to claim 1, wherein a width of said connecting strips is different than a width of said strips in the machine transverse direction.

9. The fabric according to claim 1, which comprises auxiliary strips provided if an extension of said connecting strips into said strips is less than 50% of a width of said connecting strips, said auxiliary strips being dimensioned such that a layer formed from said auxiliary strips and said connecting strips is formed without gaps in the machine transverse direction.

10. The fabric according to claim 1, which comprises at least one layer of staple fibers arranged on one or both sides of said strips or between layers of said strips.

11. The fabric according to claim 10, wherein said at least one layer of staple fibers are multiple staple fiber layers which have the same or different weights per unit area and/or the same or different fiber thicknesses.

12. The fabric according to claim 10, wherein multiple strips are provided with at least one common staple fiber layer.

13. The fabric according to claim 10, wherein said at least one layer of staple fibers is needled with said strips.

14. The fabric according to claim 10, which further comprises one or more functional layers arranged as a covering layer in one or more or all of the following positions: on said strips; on said connecting strips; between the layers of said strips; on said at least one staple fiber layer; between staple fiber layers; and/or on an uppermost said staple fiber layer.

15. The fabric according to claim 14, wherein said one or more functional layers are selected from the group consisting of films, foils, woven fabrics, laid fabrics, crocheted fabrics, knitted fabrics, nonwovens, and impregnations.

16. A fabric, comprising: a plurality of strips disposed beside one another and extending substantially parallel to one another in a machine direction; said strips together forming a width of the fabric in a machine transverse direction; each said strip being formed as a double-layer sheet material; connecting strips connecting mutually adjacent strips that are arranged beside one another in pairs to one another; a part of a width of each of said connecting strips extending in the machine transverse direction into the two adjacent said strips; and wherein said strips are connected to said connecting strips; and at least one layer of staple fibers arranged on one or both sides of said strips or between layers of said strips and needled with said strips.

17. A method of producing the fabric according to claim 1, the method comprising: i) producing a double-layer strip; ii) laying a single-layer or multilayer connecting strip in or on the double-layer strip over a sub region of a width of the connecting strip; iii) covering the strip with at least one staple fiber layer; iv) needling the at least one staple fiber layer with the strip and the partial width of the connecting strip extending in the strip; and v) repeating steps i) to iv) as far as the overall width of the fabric as seen in the machine transverse direction.

18. The method according to claim 17, wherein method step i) comprises the following partial steps: i.i) providing a sheet material; i.ii) cutting a section of the sheet material to length to approximately four times a length of the fabric to be produced; i.iii) connecting end edges of the section to produce an endless tube-like material; i.iv) laying the section on itself to produce a double-layer strip; i.v) positioning a connecting point of the end edges at a distance from the ends of the strip.

19. The method according to claim 17, wherein method step ii) comprises the following partial steps: ii.i) cutting a section of the sheet material to length to at least approximately twice a length of the fabric to be produced in order to produce a connecting strip; ii.ii) laying a total length of the connecting strip in or on the strip in a sub region of the width of the strip, the sub region being at least 5% thereof.

20. The method according to claim 19, wherein method step ii) further comprises, as a further partial step, laying auxiliary strips in or on if the extension of the connecting strips into the strips is less than 50%, wherein the auxiliary strips are dimensioned such that a layer formed from the auxiliary strips and the connecting strips has no gaps in the machine transverse direction.

21. The method according to claim 17, which comprises, following step v), making the fabric endless in a step vi), which comprises: vi.i) forming terminal seam loops at both ends of the strips, which are formed in one piece with the strips or are connected detachably or non-detachably thereto; vi.ii) laying the seam loops of the ends in one another; and vi.iii) connecting the seam loops by way of a push-in wire.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

(1) The invention will be described in more detail below with reference to the drawings, without restricting generality, by using preferred exemplary embodiments. In the figures:

(2) FIG. 1 shows a plan view of a fabric according to the invention,

(3) FIG. 2 shows a highly schematic lateral illustration of the fabric according to FIG. 1, and

(4) FIG. 3 shows a schematic lateral illustration of the fabric according to FIG. 2 with the viewing direction rotated through 90°.

DESCRIPTION OF THE INVENTION

(5) It should be pointed out that the invention is not restricted to the embodiments of the examples described but is determined by the scope of the appended patent claims. In particular, the individual features in embodiments according to the invention can be implemented in a different number and combination than in the examples listed below. In the figures, the same or similar designations are used for functionally equivalent or similar characteristics, irrespective of specific embodiments.

(6) FIG. 1 shows a fabric 1 in a schematic illustration. The fabric 1 can in particular be embodied as a press felt but also other fabric types such as forming and drying fabrics, and transport belts produced by means of the addition of polymer components can be imagined embodied in the manner of the invention.

(7) Here, the fabric 1 comprises a plurality of substantially parallel strips 2.1, 2.2 . . . 2.n, which overall form the total width of the fabric 1. Here, the strips 2.1, 2.2 . . . 2.n are produced in the way described below. First of all, a sheet material is produced which, for example, can be produced in a known way as a flat fabric made of mutually crossing warp and weft threads in any desired weaving patterns. Alternatively, it is also possible to use spiral structures which have a number of plastic spirals which are laid down so as to interengage and are connected to one another by push-in wires. In addition, prefabricated tapes, laid fabrics, knitted fabrics, crocheted fabrics can be used, as can flat structures in the form of films. The sheet material can preferably have a width between 30 cm and 600 cm.

(8) Following the production of the sheet material in any desired length, which is possible quickly and economically on familiar weaving machines, a piece is severed therefrom which corresponds approximately to four times the length of the subsequent fabric 1 as seen in a machine direction MD plus an addition for overlaps. The severed piece is folded and laid on itself, so that a material is produced which has double layers and is half the length of the severed piece. As a result, a first double-layer strip 2.1 has been produced. End edges are connected to form an endless tube-like material by fraying out some terminal yarns oriented in the machine transverse direction CD and subsequently interlacing and connecting the yarn ends oriented in the machine direction. Here, the connection can preferably be made by means of ultrasonic welding, laser welding, adhesive bonding, sewing or similar suitable methods. The connecting point between the end edges is not terminal, however, but is preferably arranged in approximately one third of the length of the strip 2.1.

(9) The first of the double-layer strips 2.1 produced in this way is combined in a next step with a first connecting strip 3.1, having one layer in the exemplary embodiment, by the latter being laid between the layers of the double-layer strip 2.1. The first one-layer connecting strip 3.1 is likewise severed from the endless sheet material and has substantially the same length as the double-layer strip 2.1, that is to say twice the length of the fabric 1 to be produced. The positioning is carried out in such a way that the one-layer connecting strip 3.1, as seen in the machine transverse direction, is pushed in approximately as far as the center of the two-layer strip 2.1. The second half of the one-layer connecting strip 3.1 thus initially remains visible.

(10) The thus combined semi-finished product comprising a double-layer strip 2.1 and a connecting strip 3.1 laid halfway in the latter is covered with at least one layer of staple fiber layers and, by using a needling machine, which advantageously has to have only the width of the double-layer strip 2.1, with which the at least one staple fiber layer is needled. In a known way, multiple staple fiber layers can be applied to one or both sides of the strip 2.1. The staple fiber layers can have different weights per unit area and fiber thicknesses. Furthermore, it is possible to introduce additional functional layers in the form of foils, membranes, films or else impregnations on the strip 2.1 or between the staple fiber layers. It is possible for further method steps of fusing the functional layers on, injecting and subsequently fusing particles on, etc, to be carried out. The number and type of these steps depends on the desired range of properties and on the position of use of the fabric 1. Since these steps are known per se, it is possible to dispense with an extensive description at this point.

(11) Following the needling, a further double-layer strip 2.2, which has been produced in the above-described way, is positioned beside the first double-layer strip 2.1 and lying edge to edge with the latter, by the still visible part of the first connecting strip 3.1 being inserted into the newly arrived double-layer strip 2.2. From the other side, a second one-layer connecting strip 3.2 is added, being positioned between the layers of the second double-layer strip 2.2. After the material has been pushed into the needling machine in the machine transverse direction by the width of a strip 2.1, 2.2, . . . 2.n, the needling step is repeated following the addition of the desired number of staple fiber and/or functional layers.

(12) The steps described above are then repeated until the complete width of the fabric 1, as seen in the machine transverse direction, is reached.

(13) The strips 2.1, 2.2, . . . 2.n each lie beside one another edge to edge, the connecting strips 3.1, 3.2, . . . 3.n lie in the interior of the strips 2.1, 2.2, . . . 2.n, likewise edge to edge. The result is thus an overall three-layer structure formed without gaps. This is illustrated highly schematically in FIG. 2 in a section in the machine transverse direction.

(14) It is also possible to see in FIG. 2 how marginal regions 4 can be formed. Here, either half the width of the marginal strips 2.1 and 2.n can remain empty without the third layer made of the part of a connecting strip 3.x being added, which is generally not a problem, since the marginal regions 4 always have somewhat of a protrusion with respect to a fiber web resting on the fabric 1. Alternatively, as can be seen from FIG. 2, half a connecting strip 3.x can be inserted, then terminating flush with outer edges 5 of the first strip 2.1 and of the last strip 2.n.

(15) In FIG. 3, the fabric 1 according to the invention is illustrated in the region of terminal seam loops 6, likewise in a side view but in a viewing direction rotated through 90° with respect to FIG. 2.

(16) As already explained above, each of the strips 2.1, 2.2, . . . 2.n has a length which corresponds substantially to twice the length of the subsequent fabric 1. In order to make the fabric 1 endless, some of the yarns oriented in the machine transverse direction are removed at end edges 7 of the strips 2.1, 2.2, . . . 2.n. In the case of a spiral structure, a spiral additionally provided for this purpose or a seaming element can be attached. Films must likewise be equipped with a seaming element.

(17) As a result of the removal of the yarns, seam loops 6 are formed which, with seam loops 6 which are formed in the same way at the other end of the strips 2.1, 2.2, . . . 2.n, can be connected to one another in the fiber web machine by the insertion of a push-in wire 8, forming an endless fabric 1.

(18) In order to prevent a gap from occurring in the staple fiber layers in the region of the seam loops 6, here a slight excess length of the staple fiber layers needled onto the strips 2.1, 2.2, . . . 2.n can provide a remedy.

(19) It should be noted that above, the exemplary embodiment illustrated in the figures was viewed in more detail at the point where the connecting strips 3.1, 3.2, . . . 3.n are formed in one layer, the connecting strips 3.1, 3.2, . . . 3.n are inserted between the layers of the strips 2.1, 2.2, . . . 2.n, the connecting strips 3.1, 3.2, . . . 3.n have the same width as the strips 2.1, 2.2, . . . 2.n and the connecting strips 3.1, 3.2, . . . 3.n are produced from the same type of sheet material as the strips 2.1, 2.2, . . . 2.n.

(20) Alternatively, the further exemplary embodiments described below can be provided.

(21) The connecting strips 3.1, 3.2, . . . 3.n can likewise be formed with multiple layers. If, for example, the connecting strips 3.1, 3.2, . . . 3.n are formed in an identical way to the strips 2.1, 2.2, . . . 2.n, as described above, the result that follows, after combination of the connecting strips 3.1, 3.2, . . . 3.n with the strips 2.1, 2.2, . . . 2.n, is an overall four-layer material.

(22) It is likewise possible not to arrange the connecting strips 3.1, 3.2, . . . 3.n between the two layers of the strips 2.1, 2.2, . . . 2.n but on or under the strips 2.1, 2.2, . . . 2.n, and in each case such that a continuous surface is formed.

(23) In a further conceivable embodiment, provision can be made for the connecting strips 3.1, 3.2, . . . 3.n to have a width which is lower than the width of the strips 2.1, 2.2, . . . 2.n. As a result, the overlap between the strips 2.1, 2.2, . . . 2.n and the connecting strips 3.1, 3.2, . . . 3.n is correspondingly lower than 50%. The gaps produced as a result could be closed by auxiliary strips, not illustrated further, the auxiliary strips being dimensioned such that a layer formed from the auxiliary strips and the connecting strips 3.1, 3.2, . . . 3.n is formed without gaps in the machine transverse direction CMD.

(24) Alternatively, the width of the connecting strips 3.1, 3.2, . . . 3.n can also be greater than the width of the strips 2.1, 2.2, . . . 2.n. A preferred embodiment here would provide a width of the connecting strips 3.1, 3.2, . . . 3.n which is an integer multiple of the width of the strips 2.1, 2.2, . . . 2.n. As a result, it is possible to avoid butt joints without overlaps occurring.

(25) Finally, it is further possible to make the connecting strips 3.1, 3.2, . . . 3.n from a different type of sheet material than the strips 2.1, 2.2, . . . 2.n. For example, the strips 2.1, 2.2, . . . 2.n can comprise a flat woven textile with longitudinal and transverse threads, as described above, and the connecting strips 3.1, 3.2, . . . 3.n of a film or a crocheted fabric, for example.