Stock material or miscellaneous articles – Structurally defined web or sheet – Fold at edge
Reexamination Certificate
1997-07-21
2001-07-24
Cole, Elizabeth M. (Department: 1771)
Stock material or miscellaneous articles
Structurally defined web or sheet
Fold at edge
C428S130000, C428S192000, C428S193000, C028S142000, C139S3830AA, C139S3830AA, C245S010000
Reexamination Certificate
active
06265048
ABSTRACT:
The present invention generally relates to a laminated clothing, such as a laminated press felt, for use in a papermaking or cellulose manufacturing machine. More specifically, the invention relates to a clothing having in its thickness direction a first and, laminated therewith, a second layer, each having a direction-defined thread system, said thread systems making an angle with the machine direction of the clothing and with one another. The invention also relates to a method and a blank for manufacturing such a laminated clothing. SE 468,602 discloses a laminated press felt of the above-mentioned type, and a method of manufacturing the same.
The press felt in a papermaking machine has, like other clothings (forming fabrics, drier fabrics etc.), changed a great deal in the last decades. A modern press felt comprises a soft compressible part adjacent to the paper web for protection, and a relatively incompressible part, called base fabric, for receiving and removing water pressed out in the press nips. The compressible part usually is a single- or double-face fiber layer needled to the base fabric. The base fabric usually consists of woven monofilaments, but also spun threads or twisted multifilaments are used. As material in the fibre layer and the base fabric, use is often made of polyamide, which is an impact-resistant fibre that does not fibrillate owing to repeated compressions in a press nip.
At the beginning of the 70's, it was considered in this technical field that future press felts would contain a small amount of base fabric or even be completely without base fabric. However, the development has been completely reversed. More rapid machines having greater and greater pressing pressures have required press felts of higher and higher stability, improved strength properties and conditionability, and therefore the amount of press felts having a thicker base fabric and multilayer design has increased constantly.
In so-called laminated press felts, which are a special type of multilayer press felts and which have implied a great step forward, two base fabrics are included, which have separate thread systems and which are combined, i.e. laminated, while manufacturing the felt. Laminated press felts are particularly used in highly loaded press positions where large amounts of water are to be processed, in many cases requiring low marking. By different combinations of top and bottom fabrics it has been possible to adapt the structure to demanding machine positions.
At the beginning of the 90's, a new type of laminated press felt was introduced, marketed under the designation DYNATEX™ supplied by Albany International Corp., at least one of the two base fabrics, i.e. one of the two layers laminated with each other, consisting of a spirally rolled strip, preferably a flat-woven strip. This spirally rolled base fabric is the subject matter of SE 468,602 mentioned by way of introduction. The principle is illustrated in
FIG. 1
on the accompanying sheet of drawing, which illustrates schematically and from above a method of manufacturing such a spirally rolled base fabric. Two rotatably mounted rollers
10
,
12
having parallel axes are arranged at a mutual axial distance D. A supply coil
14
is rotatably arranged about an axis
16
and movable in parallel with the shafts
10
and
12
, as indicated by arrow
18
. The supply coil
14
accommodates a rolled-up supply of a flat-woven strip
20
of fabric made from yarn, having a width w between its longitudinal edges
26
and
28
. The strip
20
is composed of two mutually perpendicular thread systems consisting of longitudinal threads (warp threads) and transverse threads (weft threads), respectively, schematically shown at
22
and
24
, respectively. As the supply coil
14
is moved from the left to the right in the Figure, the strip
20
is discharged in the direction of arrow
30
to be spirally rolled about the shafts
10
,
12
into an endless product, below called “endless band”, generally designated
40
. The final width of the band
40
is designated B and is defined by lines
34
and
36
along which the sides of the band
40
are cut after the spiral rolling.
As illustrated in
FIG. 2
, the strip
20
is applied at an angle &agr; to the machine direction which is designated MD and which is the running direction of the finished press felt in the machine. The longitudinal edges
26
,
28
of the strip
20
can be made to be positioned edge by edge or in overlapping fashion, preferably joined together. The completed, laminated press felt has a width B which is determined by the number of spiral turns, and a length equalling approximately twice the axial distance D and thus easily being possible to vary by changing D. The advantages of this prior-art spiral rolling is disclosed in SE 468,602 and will not be repeated here.
A special advantage has been obtained with a multiaxial variant of DYNATEX™, where two spirally rolled endless base fabric bands as described above are laminated in such a manner that the spiral turns of one band intersects the spiral turns of the other band. It is possible to manufacture such a multiaxial, laminated base fabric by spirally rolling a first base fabric band according to
FIG. 1
, and spirally rolling a second base fabric band of essentially the same length, but of opposite pitch angle (i.e. the strip in the second base fabric band is directed obliquely upwards to the right instead of obliquely upwards to the left as in FIG.
1
). Subsequently, these two endless bands are inserted into one another to form a laminated base fabric, which, seen from above, has on the one hand two systems of longitudinal threads
22
making an angle with each other and with the machine direction MD and, on the other hand, two systems of transverse threads
24
making an angle with each other as well as with the longitudinal threads
22
and the machine direction MD, i.e. totally four thread directions. The multiaxial, laminated base fabric can then be provided with a needled batt layer, which produces a joining effect on the two layers. The resultant product is called a multiaxial, laminated press felt.
Runs with multiaxial laminated press felts have conferred a number of advantages, mainly an improved stability as to shape under pressure thanks to the crossing of the thread systems preventing them from sliding into each other, i.e. improved incompressibility. A further advantage is that the life of the press felt increases since it will keep more open for a longer time and, thus, its properties change less in time.
A problem of the multiaxial laminated press felt, however, is that the manufacture thereof in respect of lamination is relatively complicated and time-consuming.
A further problem of the multiaxial laminated press felt is that it has no openable seam, and therefore cannot be installed and run in machine positions requiring a seamed felt.
A special difficulty regarding the problem of the missing openable seam is that modern techniques for manufacturing openable seams can be used for “perpendicular” thread systems only, i.e. thread systems running in MD (machine direction) and CD (cross machine direction).
To solve the first problem—a complicated and time-consuming manufacture—the invention suggests a laminated clothing and a method for manufacturing a laminated clothing having the features defined in claims
1
and
7
, respectively. According to one aspect of the invention, also a blank intended for the manufacture of a laminated clothing is provided according to the claim
14
.
The term “clothing” means either a finished product for installation, for instance a press felt comprising a laminated base fabric and, needled thereto, a batt, or part of a finished product, for instance merely a laminated base fabric for a press felt. The term “clothing” should further not be considered limited to the field of press felts. Other possible fields of application for the invention are LNP bands (long nip presses), transfer bands, clothings for forming or drying, etc.
Thus, according to the invent
Horanburg Douglas L
Rydin Bjorn
Albany International Corp.
Cole Elizabeth M.
Pitney Hardin Kipp & Szuch LLP
LandOfFree
Laminated clothing, as well as method and blank for... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Laminated clothing, as well as method and blank for..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Laminated clothing, as well as method and blank for... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2559194