Textiles: weaving – Fabrics – Drier felts
Reexamination Certificate
2000-05-18
2001-12-25
Falik, Andy (Department: 3765)
Textiles: weaving
Fabrics
Drier felts
C162S902000
Reexamination Certificate
active
06332480
ABSTRACT:
FIELD OF THE INVENTION
The invention concerns a paper machine clothing, in particular as a dryer fabric, having a paper side provided for the support of a paper web and a machine side facing away therefrom, the paper machine clothing having or comprising a fabric made of longitudinal and transverse threads, and each two adjacent longitudinal threads engaging at the same height with transverse threads to form a longitudinal thread pair.
BACKGROUND
A dryer fabric of this kind is disclosed in EP 0 609 664 A1. It comprises a single-ply fabric having round transverse threads that can also be configured as hollow monofilaments, and having two longitudinal thread systems, the longitudinal threads being embodied as flat monofilaments. One of the longitudinal thread systems extends predominantly on the paper side, each two adjacent longitudinal threads forming a longitudinal thread pair that engages at the same height with the transverse threads. With the second longitudinal thread system, one longitudinal thread runs in each case below a longitudinal thread pair.
If dryer fabrics such as those evident from EP 0 609 664 A1 are woven flat, their length is finite, so that after installation into the paper machine their ends must be joined together. EP 0 609 664 A1 contains nothing concerning the manner in which this occurs with the dryer fabric disclosed therein.
It is known in the existing art to join the ends of paper machine fabrics using a so-called inserted wire seam. For this purpose, eye-forming loops are configured at the ends and are made to overlap when the edges are fitted together, so that the eyes of the loops of the two ends align and consequently form a passage into which an inserted wire can be slid. This inserted wire couples the eyes of the two ends, and thus makes the paper machine clothing endless.
In many cases the longitudinal threads of the paper machine fabrics are utilized to form the loops, by the fact that some of the longitudinal threads are guided out beyond the last transverse threads and woven back into the fabric forming an eye, while others of the longitudinal threads are woven back in directly, i.e. without forming an eye (cf. U.S. Pat. Nos. 5,089,324, 4,438,789). With the fabrics disclosed in these documents, the weaving back is accomplished in such a way that the woven-back portion of the respective longitudinal thread is engaged next to the latter, and the profile of this portion does not deviate from that of the longitudinal thread in question. In the paper machine fabric described in EP 0 532 510 B1, the woven-back portion is introduced back into the fabric below the relevant longitudinal thread so that the loops are not subject to twisting.
It is the object of the invention to configure the ends of a paper machine clothing of the kind cited initially, for the purpose of creating an inserted-wire seam, in such a way that the weave pattern is consistent, in particular on the paper side, over the entire length of the paper machine clothing .
SUMMARY OF THE INVENTION
According to the present invention, this object is achieved in that at each of the ends of the paper machine clothing, the longitudinal threads of a longitudinal thread pair form a loop with the adjacent longitudinal threads of the adjacent longitudinal thread pair. The basic idea of the invention is thus to weave back the longitudinal thread structure of the loops in such a way that the longitudinal threads which belong together as the result of a loop run adjacently but belong to two different adjacent longitudinal thread pairs. In this type of longitudinal thread system, each of the two longitudinal threads in a given longitudinal thread pair has a same repeated weaving pattern that is in phase. This type of longitudinal thread guidance guarantees a uniform weave pattern on the paper side over the entire length of the paper machine clothing, at the same time forming loops for an inserted wire seam. The properties of the paper machine clothing are therefore influenced over the entire length by the paired guidance of the longitudinal threads.
In an embodiment of the invention, it is provided that alternately one loop is laid closely around the last transverse thread, and one loop is of pulled-out configuration to form a loop eye. Instead of this, all the loops can also be of pulled-out configuration in order to form a loop eye.
In a further embodiment of the invention, it is provided that adjacent longitudinal thread pairs engage the transverse threads in opposite directions. If some or all of the transverse threads are configured as flat transverse threads, the longitudinal thread pairs should each engage only one of the flat transverse threads.
According to a further feature of the invention, it is provided that in each case at least two transverse threads configured as round transverse threads lie in contact on the machine side of at least some of the transverse threads configured as flat transverse threads, and in each case one flat transverse thread and its round transverse threads lying in contact with it are together engaged by at least some of the longitudinal threads. This configuration is characterized by particular dimensional stability.
It is not necessary for the round transverse threads lying in contact with one flat transverse thread on the machine side to lie in contact with one another. Shifting of the round transverse threads with respect to the flat transverse threads is reduced, however, if the round transverse threads touch one another. In this context, the sum of the diameters of the round transverse threads that lie in contact with one flat transverse thread should not be greater than its extension in the longitudinal direction, so that the round transverse threads do not project beyond the flat transverse threads.
In a further embodiment of the invention, it is provided that no further transverse threads are present besides the flat transverse threads and the round transverse threads lying in contact with them, i.e. that what is always present is a combination of flat transverse threads and round transverse threads supporting them. As an alternative to this, however, it can also be provided that some of the longitudinal threads engage the flat transverse threads only on the paper side, and otherwise engage only with round transverse threads that extend between the round transverse threads lying in contact with the flat transverse threads.
As an alternative to the combination described above of flat and round transverse threads, it is provided tat at least some of the transverse threads are configured as flat transverse threads onto which are shaped longitudinal ribs projecting on the machine side, the longitudinal ribs extending in the direction of the longitudinal axis of the flat transverse threads. This feature again provides dimensional stability for the transverse threads and ensures that the smooth paper-side surface of the flat transverse threads remains as flat as possible and thus supports the paper web over the largest possible area. Flat transverse threads of this kind can be manufactured by extrusion of the plastic material that is used.
The longitudinal ribs can be adapted to the respective requirements and manufacturing capabiliities, and within this context can have any desired cross section. Rectangular, trapezoidal, and/or round cross sections are particularly appropriate. The number of longitudinal ribs is in principle not limited. Particularly favorable conditions are created if two or three longitudinal ribs are shaped next to one another.
The flat transverse threads advantageously have an extension in the longitudinal direction (machine direction) of the paper machine clothing of 1 to 25 mm, preferably 10 to 15 mm, and in the thickness direction (perpendicular to the plane of the paper machine clothing) of 0.2 to 1 mm. By definition, however, the term “flat transverse reads” always encompasses only those in which the thickness is less than the extension in the longitudinal direction of the paper machine clothing. The longitudinal threads can a
Falik Andy
Liniak, Berenato, Longacre & White LLC
Thomas Josef Heimbach Gesellschaft mit beschrankter Haftung & Co
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