CN108457118B

CN108457118B - Drying net, drying part and use of drying net in drying part

Info

Publication number: CN108457118B
Application number: CN201810041453.7A
Authority: CN
Inventors: 弗朗西斯科·卡斯孔
Original assignee: Heimbach GmbH and Co KG
Current assignee: Heimbach GmbH and Co KG
Priority date: 2017-02-22
Filing date: 2018-01-16
Publication date: 2020-07-24
Anticipated expiration: 2038-01-16
Also published as: PT3366835T; EP3366835A1; EP3366835B1; CN108457118A; ES2719687T3; DE202017100990U1

Abstract

The invention relates to a drying wire, a drying section and the use of a drying wire in the drying section, which is suitable for use in a drying section of a paper machine, having a certain paper side for contacting a paper web and a machine side facing away from the paper side, wherein the drying wire has or consists of a fabric of longitudinal yarns (2-7) and transverse yarns (10-21), which fabric comprises at least two superposed layers of transverse yarns, wherein the longitudinal yarns bind the transverse yarns with a paper-side and machine-side float pattern, the float pattern being staggered on the paper and machine sides, and the fabric has only a longitudinal yarn float pattern on the paper and machine sides, which overlaps at least two adjacent transverse yarns, respectively, and all the longitudinal yarn float patterns overlap the same number of transverse yarns.

Description

Drying net, drying part and use of drying net in drying part

Technical Field

The present invention relates to a drying wire, which is suitable for use in the drying section of a paper machine. The invention furthermore relates to a drying section of a paper machine equipped with such a drying wire and to the use of a drying wire in such a drying section of a paper machine.

Background

Large paper machines are usually built up of three so-called sections, namely a forming section, a pressing section and a drying section, seen in the direction of the paper web. The forming member is used for structuring a paper web of pulp and for first mechanical drainage of the paper web formed thereby. In the press section, the paper web is guided through between press rolls, in which the paper web is subjected to high pressure and is thereby further mechanically drained. Subsequently, the web is transported to a drying section, in which the web is guided over a heated drying cylinder, whereby the web is thermally drained.

The guiding of the paper web through the paper machine is effected by means of belts adapted to the requirements of the respective components, against which the paper web rests, and which are also used for transferring the paper web from one component to the next. In the drying section, a so-called drying wire is installed, which is designed in particular as a drying fabric made up of warp threads and weft threads. The dried web is obtained, for example, from EP 1507041B 1.

In principle, it is desirable to provide as large a contact surface as possible for the paper web on the paper side of the drying wire, in order to press the paper web as uniformly as possible against the drying cylinder and thus to produce a correspondingly uniform heating and drying of the paper web with good heat transfer. In order to indicate the sheet contact of the drying wire, a so-called Fiber Fineness Index (FFI) was developed by the clothing association of the paper machine (PCA; address: 19, rue dela R é pubique, 45000 orlar, france) (PCA standard grade, november, 2009, 15 th edition, page 3A, No. 15). FFI is calculated according to the following formula:

the knowledge of the various components of the formula is achieved according to the "examined Standard measurement Methods" in the document 12 months 2013, also issued by the clothing association of paper machines. The predetermined variables for the thickness measurement are obtained from paragraph C2 on two pages, the predetermined variables for determining the contact surface and its surface fraction and the number of contact points are obtained from paragraph C11 on pages 1 to 4.

From DE 202015103812U 1 a drying wire is obtained, characterized in that the ratio of FFI-MS on the machine side to FFI-PS on the paper side is at least 1.25 to 1, preferably at least 1.5 to 1. Percentage of contact surface and/or per cm²Is significantly larger on the machine side, thereby resulting in a drying wire with a relatively open and thus easy to clean paper side and machine side, which is characterized by a long service time because the machine side provides significantly more wear resistance (Abriebvolumen).

Previously known drying webs have proven suitable in principle. However, there is also a need for alternative drying nets.

Disclosure of Invention

The object of the invention is therefore to specify an alternatively designed drying wire which enables uniform drying and which is characterized by a service life which is as long as possible.

This object is achieved according to the invention by a drying wire which is suitable for use in a drying section of a paper machine and has a certain paper side for contacting a paper web and a machine side facing away from the paper side, wherein the drying wire has or consists of a fabric composed of lengthwise and crosswise yarns, which fabric comprises at least two superposed layers of crosswise yarns, wherein the lengthwise yarns bind the crosswise yarns with a float structure on the paper side and the machine side, the float structure being alternately located on the paper side and the machine side, and the fabric has only a lengthwise yarn float structure on the paper side and the machine side, the lengthwise yarn float structures respectively overlapping at least two adjacent crosswise yarns, and all the lengthwise yarn float structures overlapping the same number of crosswise yarns.

In other words, the drying wire according to the invention comprises a fabric without folds of longitudinal yarns on the respective transverse yarns, or the drying wire according to the invention is composed of a fabric without folds of longitudinal yarns on the respective transverse yarns. Only the longitudinal yarn floats are present, i.e. always at least two adjacent transverse yarns are overlapped by a longitudinal yarn. In the dryer wire according to the invention, all the longitudinal yarn floats run on the same number of transverse yarns on the paper side and on the machine side. Furthermore, in the dryer wire according to the invention, the longitudinal yarn floats are alternately located on the paper side and on the machine side. For the course of each longitudinal thread of the fabric, it applies that the float pattern on one fabric side follows the float pattern on the other fabric side and repeats this. The float stitches of the longitudinal threads on one fabric side are therefore each located between two successively following float stitches of the longitudinal threads on the other fabric side.

The use of a longitudinal yarn float weave of the same length interlaced on both fabric sides results in a particularly uniform, to some extent symmetrical fabric structure and thus a particularly uniform appearance.

The uniform fabric structure of the drying wire according to the invention on the one hand contributes to an increase in the number of contact points and/or an increase in the contact surface on both fabric sides and thus to a high FFI value, so that there is a large contact surface for the paper web and at the same time a high amount of wear resistance on the machine side can be provided.

On the other hand, particularly good orientation for the continuous configuration of the loops (Nahtschlaufen) can be achieved with the dryer wire according to the invention. In flat fabrics from the paper machine area, two fabric edges passing transversely to the lengthwise threads are usually formed in such a way that the lengthwise threads are woven back into the fabric body with loops formed, i.e., in the plane of the adjacent lengthwise threads, the adjacent lengthwise threads are shortened until they reach with their ends the end sides of the ends of the lengthwise threads woven back.

The section of the longitudinal threads that is woven back is bundled in this case, so that it continues into the fabric structure of the shortened longitudinal threads until the fabric edge is reached. In this case, a part of the loop is formed in such a way that the correspondingly adapted free longitudinal section of the woven back longitudinal thread projects somewhat beyond the two woven edges in order to form a loop for a plug-in connection (stepdrahtnahtverbindung). For this purpose, the stitches of one fabric edge are arranged in such a way in comparison with the stitches of the other fabric edge that they overlap each other in a combed manner when joining the fabric edges, so that a channel for threading the insert thread is formed by them. The insert thread thus forms a connection of the fabric edges on both sides, so that a continuous woven fabric (maschinenbespinning) is obtained.

The dryer wire according to the invention enables a uniform, twist-free orientation of the stitches by virtue of the fact that the "waves" formed into the fabric yarns during the weaving-in of the weaving-in are actually "positively (formscl ü ssig)" embedded in the fabric structure during the folding-back of every other longitudinal yarn end and the weaving-in back into the respectively directly adjacent initial weaving path of the respectively truncated longitudinal yarn, without the longitudinal yarns having to be twisted by another 180 ° during the folding-back.

The design according to the invention eliminates the teaching known from the prior art, according to which the fabric has an asymmetrical structure with respect to the two fabric sides (with a plurality of contact surfaces and/or contact points on the machine side) and folds on the respective cross threads.

The longitudinal yarns of the fabric of the drying wire according to the invention are, in particular, warp yarns and the transverse yarns are, in particular, weft yarns.

An embodiment of the drying wire according to the invention is characterized in that the fabric has only a longitudinal yarn float on exactly two adjacent transverse yarns, or only a longitudinal yarn float on exactly three adjacent transverse yarns, or only a longitudinal yarn float on exactly four adjacent transverse yarns. The float stitch length on both cross threads is particularly preferred here.

Alternatively or additionally, it can be provided that each longitudinal thread between at least one, preferably exactly one, pair of superimposed transverse threads extends between the float stitches on one fabric side and the respectively adjacent float stitch on the other fabric side. The adjacent longitudinal thread floats on the opposite fabric side are then each spaced apart from one another by at least one, preferably exactly one, transverse thread, and the longitudinal threads are guided through the superimposed pairs of transverse threads in a corresponding manner from one float to the next float on the other fabric side.

Furthermore, the number of machine-side transverse threads relative to the number of paper-side transverse threads may be, in particular, 1: 1.

In a further advantageous embodiment, it is provided that the fabric has exactly two cross yarn layers and/or exactly one longitudinal yarn layer, wherein a combination of exactly two cross yarn layers and exactly one longitudinal yarn layer has proven particularly suitable.

In a particularly advantageous embodiment of the dryer wire according to the invention, the fabric pattern of the fabric comprises: a paper-side cross-yarn layer with six side-by-side cross-yarns and a machine-side cross-yarn layer with six side-by-side cross-yarns and six side-by-side lengthwise yarns. The transverse threads of the paper-side transverse thread layer and the transverse threads of the machine-side transverse thread layer then form, in particular, a transverse thread pair with two corresponding transverse threads lying one above the other. The binding with each lengthwise thread is then preferably such that each lengthwise thread overlaps two adjacent pairs of crosswise threads in a float weave on the paper side, then extends between the next pair of crosswise threads, then overlaps two adjacent pairs of crosswise threads in a float weave on the machine side, and finally passes between the next pair of crosswise threads. The side-by-side lengthwise threads of the fabric pattern are then preferably offset in their course by at least one, in particular at least two, pairs of crosswise threads. This structure has proved to be particularly suitable for the dryer wire according to the invention.

Obviously, the machine-side and paper-side longitudinal-thread floats can also overlap more than two transverse threads next to one another in this embodiment. For example, a succession of arrangements can be provided according to which each longitudinal thread float stitch extends over three adjacent transverse threads before the longitudinal threads are guided to the other fabric side. The fabric patterns in the paper-side and machine-side transverse yarn layers then each comprise eight transverse yarns arranged next to one another and eight longitudinal yarns arranged next to one another, wherein adjacent longitudinal yarns are preferably offset from one another in their course by at least one transverse yarn pair, in particular two transverse yarn pairs. It is also possible to provide a longitudinal yarn float pattern on four or more transverse yarns, wherein the number of transverse and longitudinal yarns of the pattern is then correspondingly increased.

According to a further embodiment, it is provided that the paper side and the machine side each have a contact point formed by a textile yarn, the contact points each have a contact surface, and the contact surfaces of the contact points on the paper side and on the machine side each accumulate to a total contact surface with a contact surface fraction in percent over the entire paper side or machine side, and the drying wire has a textile thickness, wherein a fiber fineness index (FFI-PS) for the paper side and a fiber fineness index (FFI-MS) for the machine side can be calculated from the contact surface fraction, the number of contact points and the textile thickness according to the following formulae:

and the ratio of FFI-PS to FFI-MS is at least 1:0.9, especially at least 1:0.95, or the ratio of FFI-MS to FFI-PS is at least 1:0.9, especially at least 1: 0.95.

It has proven particularly suitable for the paper side and the machine side to be characterized by a contact surface proportion in the range from 35% to 45%, in particular from 38% to 41%.

In terms of fabric thickness, it may lie in particular in the range from 1.0mm to 1.8mm, preferably in the range from 1.3mm to 1.5 mm.

The cross section of the textile yarns can furthermore be symmetrical or asymmetrical and/or round, oval, polygonal, in particular rectangular.

In the case of a rectangular cross section, one of the two edge lengths is preferably in the range from 0.3mm to 0.4mm and the other edge length is preferably in the range from 0.6mm to 0.7mm, in the case of a transverse yarn. For example, in a preferred embodiment, it can be provided that one edge length is 0.66mm and one edge length is 0.33 mm.

In the rectangular cross section of the cross-thread, the longer side is oriented parallel to the paper side and the machine side, and the shorter side is perpendicular thereto.

Polymeric materials have proven suitable as materials for textile yarns. PPS (polyphenylene sulfide), PET (polyethylene terephthalate) or PEEK (polyetheretherketone) are particularly suitable for this purpose, mixtures of these also being possible. Furthermore, textile yarns of different materials can be used, and in this case also materials different from the previously mentioned polymeric materials can be used.

The invention also relates to a drying section of a paper machine, comprising a plurality of heated drying cylinders and at least one drying wire guided over the drying cylinders. According to the invention, a drying wire as described above is used here, i.e. the paper web is in contact with the paper side of the drying wire in a conventional manner.

Finally, the subject of the invention is the use of a drying wire according to the invention in a drying cylinder of a paper machine in such a way that the paper web guided through the drying means is in contact with the paper side of the drying wire.

Drawings

The invention is illustrated in detail in the drawings by means of examples. Wherein:

figures 1 to 6 show, in schematic and in the case of six side-by-side warp threads showing the fabric pattern, a longitudinal section through an embodiment of a drying wire according to the invention, which is limited by a fabric pattern;

figures 7 to 12 show, in schematic and side by side view, and with six pairs of weft threads respectively superimposed on two of the two phases, of the fabric pattern, a cross-section through a drying wire according to figures 1 to 6, which drying wire is limited by the same fabric pattern;

fig. 13 shows a laser scan of the contact points and their contact surfaces of the sections of the paper side of the drying wire according to fig. 1 to 6, page 4 of the above-mentioned document "standard measurement under test", paragraph C11, corresponding to PCA; and

fig. 14 shows a corresponding laser scan of the contact points and their contact surfaces of the machine-side sections of the drying wire according to fig. 1 to 6.

Detailed Description

Fig. 1 to 12 show sections of an embodiment of a drying wire according to the invention with the fabric pattern 1 of the drying wire fully shown, wherein the side directed upwards in the figure forms the paper side and the side directed downwards in the figure forms the machine side. Fig. 1 to 6 show longitudinal section views through a fabric pattern 1, from which a run of six side-by-side warp threads 2 to 7 is obtained, which form a warp pattern. Fig. 7 to 12 furthermore show cross-sectional views through the textile pattern 1.

As can be seen from the figure, the drying wire has two

layers

8, 9 of weft threads, in particular a layer 8 of paper-side weft threads and a layer 9 of machine-side weft threads. Here, in each fabric pattern 1, the paper-side weft layer 8 comprises six weft threads 10 to 15 and the machine-side weft layer 9 likewise comprises six weft threads 16 to 21. The weft threads 10 to 15 of the paper-side weft thread layer 8 form here with the weft threads 16 to 21 of the machine-side weft thread layer 9 weft thread pairs with two weft threads 10, 16 (fig. 1 to 6 and 7) or 11, 17 (fig. 1 to 6 and 8) or 12, 18 (fig. 1 to 6 and 9) or 13, 19 (fig. 1 to 6 and 10) or 14, 20 (fig. 1 to 6 and 11) or 15, 21 (fig. 1 to 6 and 12) lying one above the other. The ratio of the number of weft threads 10 to 15 of the paper-side weft thread layer 8 to the number of weft threads 16 to 21 of the machine-side weft thread layer 9 is 1: 1.

The warp thread 2 shown in fig. 1, viewed from left to right, passes first on the paper side over two adjacent pairs of weft threads consisting of

weft threads

10, 16 and 11, 17 lying one above the other, then passes between

weft threads

12, 18 lying one above the other in the longitudinal direction of the next pair of weft threads, then passes on the machine side under two pairs of weft threads consisting of

weft threads

13, 19 and 14, 20, and then passes between two

weft threads

15, 21 of the last pair of weft threads. The course is then repeated in the next textile pattern, which is not shown here.

The side-by-side warp threads 3 to 7 (fig. 2 to 6) have the same course as warp thread 2, but are offset in their course, as can be seen in contrast in the figures, to the right by a defined number of pairs of weft threads, i.e. in the longitudinal direction, i.e.

warp threads

3, 4 and 6, 7 are offset by two pairs of weft threads in each case with respect to the preceding warp thread, and warp thread 5 is offset by 3 pairs of weft threads.

The configuration of the drying wire and thus the article profile is identical on both fabric sides.

For each warp thread 2 to 7, it applies that the warp floats alternate on the paper side and on the machine side. The float stitch of the paper side warp threads takes place between two adjacent float stitches of the machine side warp threads and vice versa.

Furthermore, weft threads are present between two adjacent warp floats on the opposite fabric side, i.e. the warp floats are spaced apart from one another by one weft thread in the longitudinal direction.

As can also be seen, all the warp floats of the drying wire have the same length, which applies in particular to all the warp floats of the paper side and the machine side, which extend over exactly two side-by-side weft threads.

The weft threads 10 to 15 and 16 to 21 are furthermore characterized by a rectangular cross section, wherein the cross sections of all weft threads 10 to 15 and 16 to 21 are equally large. In particular, all weft threads 10 to 15 and 16 to 21 are characterized by edge lengths of 0.33mm and 0.66 mm.

Fig. 13 depicts the contact surface on the paper side with its white area, which is indicated by way of example at 22 in fig. 13. In the same way, fig. 14 depicts the machine-side contact surface with its white area, which is indicated by way of example at 23 in fig. 14. It can be seen that the number of paper-side contact surfaces 22 and the number of machine-side contact surfaces 23 are at least approximately the same.

Specifically, the paper side contact surface fraction was 39.67%, and the machine side contact surface fraction was 38.25%. Further, the FFI value of the paper side is 1724, and the FFI value of the machine side is 1685. The ratio of FFI-PS to FFI-MS is thus 1:0.98 in the embodiment shown.

The same fabric structure with respect to the two fabric sides results, on the one hand, in an increase in the number of contact points and/or an increase in the contact area on the two fabric sides and thus in a high FFI value, so that at the same time a high contact area for the paper web is present and a high wear resistance on the machine side can be increased.

Furthermore, the ideal orientation of the stitches necessary for a continuous configuration of the drying wire is possible. A uniform, twist-free orientation of the stitches can be achieved by the fact that the "waves" formed into the textile yarns by weaving are virtually "positively" embedded into the textile structure when every other longitudinal yarn end is folded back and woven back into the respectively immediately adjacent initial weaving path of the respectively truncated longitudinal yarn, without the longitudinal yarns having to be twisted by another 180 ° when returning.

Claims

1. A drying wire suitable for use in a drying section of a paper machine with a defined paper side for application against a paper web and a machine side facing away from the paper side, wherein the drying wire has or consists of a fabric consisting of lengthwise (2-7) and crosswise (10-21) yarns, which fabric comprises at least two superposed layers of crosswise yarns, wherein the lengthwise yarns bind the crosswise yarns with a paper-side and a machine-side float stitch, which float stitches are alternately located on the paper side and the machine side, and the fabric has only a lengthwise yarn float stitch on the paper side and the machine side, which respectively overlap at least two adjacent crosswise yarns and all of which overlap the same number of crosswise yarns, and wherein the paper side and the machine side respectively have contact points formed by the fabric yarns (2-21), the contact points each have a contact surface, and the contact surfaces of the contact points on the paper side and on the machine side each accumulate to a total contact surface with a contact surface portion in percent over the entire surface of the paper side or machine side, characterized in that the paper side and the machine side are characterized by a contact surface portion in the range of 35% to 45%.

2. Drying wire according to claim 1, characterised in that the longitudinal yarns are warp yarns (2-7) and the transverse yarns are weft yarns (10-21).

3. Drying wire according to claim 1 or 2, characterised in that the fabric has only a wale course pattern on exactly two adjacent cross threads (10-21), or only a wale course pattern on exactly three adjacent cross threads (10-21), or only a wale course pattern on exactly four adjacent cross threads (10-21).

4. Drying wire according to claim 1 or 2, characterised in that each longitudinal yarn (2-7) between at least one pair of superimposed transverse yarns (10-21) extends between a float stitch on one fabric side and a corresponding adjacent float stitch on the other fabric side.

5. Drying wire according to claim 1 or 2, characterised in that the ratio of the number of machine-side cross-threads (16-21) to the number of paper-side cross-threads (10-15) is 1: 1.

6. Drying wire according to claim 1 or 2, characterised in that the fabric has exactly two cross yarn layers (8, 9) and/or exactly one longitudinal yarn layer.

7. Drying wire according to claim 1 or 2, characterised in that the fabric pattern (1) of the fabric comprises a paper-side cross-yarn layer (8) with six side-by-side cross-yarns (10-15) and a machine-side cross-yarn layer (9) with six side-by-side cross-yarns (16-21) and six side-by-side longitudinal-yarns (2-7), wherein the cross-yarns (10-15) of the paper-side cross-yarn layer (8) and the cross-yarns (16-21) of the machine-side cross-yarn layer (9) form a cross-yarn pair with two respectively overlapping cross-yarns (10-21), and the binding with each longitudinal-yarn (2-7) is in such a way that each longitudinal-yarn (2-7) overlaps two adjacent cross-yarn pairs with a float weave on the paper side, then, the fabric pattern extends between the next transverse yarn pair, then two adjacent transverse yarn pairs are overlapped in a floating stitch on the machine side, and finally the fabric pattern passes between the next transverse yarn pair, wherein the side-by-side longitudinal yarns (2-7) of the fabric pattern (1) are staggered in the running direction of at least one transverse yarn pair.

8. Drying wire according to claim 1 or 2, characterised in that it has a fabric thickness, wherein the index of fiber fineness for the paper side (FFI-PS) and the index of fiber fineness for the machine side (FFI-MS) can be calculated from the contact surface fraction, the number of contact points and the fabric thickness according to the following formulae:

wherein the contact surface fraction is given in% and the fabric thickness in mm,

and the ratio of the index of fiber fineness for the paper side and the index of fiber fineness for the machine side is at least 1:0.9, or the ratio of the index of fiber fineness for the machine side and the index of fiber fineness for the paper side is at least 1: 0.9.

9. The dryer wire of claim 1 or 2, characterized in that the paper side and the machine side are characterized by a contact surface fraction in the range of 38 to 41%.

10. The dryer wire of claim 8, wherein the fabric thickness is in the range of 1.0mm to 1.8 mm.

11. Drying wire according to claim 1 or 2, characterised in that the cross section of the textile yarns (2-21) is symmetrical or asymmetrical.

12. Drying wire according to claim 1 or 2, characterised in that the cross-section of the cross-yarns (10-21) is rectangular.

13. Drying wire according to claim 1 or 2, characterised in that the textile yarns (2-21) consist of a polymer material.

14. A dryer wire as claimed in claim 4, characterized in that each longitudinal yarn (2-7) between exactly one pair of superimposed transverse yarns (10-21) extends between the float weave on the one fabric side and the respective adjacent float weave on the other fabric side.

15. Drying wire according to claim 7, characterised in that the side-by-side lengthwise threads (2-7) of the fabric pattern (1) are staggered in their course by at least two pairs of crosswise threads, respectively.

16. The dryer wire of claim 8, wherein the ratio of the index of fiber fineness for the paper side and the index of fiber fineness for the machine side is at least 1: 0.95.

17. The dryer wire of claim 8, wherein the ratio of the fiber fineness index for the machine side and the fiber fineness index for the paper side is at least 1: 0.95.

18. The dryer wire of claim 10, wherein the fabric thickness is in the range of 1.3mm to 1.5 mm.

19. Drying wire according to claim 11, characterised in that the cross-section of the fabric yarns (2-21) is rectangular.

20. Drying wire according to claim 12, characterised in that the cross section of the cross-yarns (10-21) has an edge length in the range of 0.3mm to 0.4mm and an edge length in the range of 0.6mm to 0.7 mm.

21. Dryer wire according to claim 13, characterised in that the textile yarns (2-21) consist of PPS, PET and/or PEEK.

22. Drying wire according to claim 1 or 2, characterised in that the cross-section of the fabric yarns (2-21) is circular, oval or polygonal.

23. Drying section of a paper machine with a plurality of heated drying cylinders and at least one drying wire guided over the drying cylinders, characterized in that the drying wire is constructed according to any of claims 1 to 22.

24. Use of a drying wire constructed according to any of claims 1 to 22 in a drying section of a paper machine in such a way that the paper web guided by the drying section is in contact with the paper side of the drying wire.