Paper making and fiber liberation – Apparatus – Running or indefinite length product forming and/or treating...
Reexamination Certificate
2000-03-24
2001-09-04
Hastings, Karen M. (Department: 1731)
Paper making and fiber liberation
Apparatus
Running or indefinite length product forming and/or treating...
C156S172000, C156S173000, C156S177000, C162S901000, C264S258000
Reexamination Certificate
active
06284102
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATIONS
Not Applicable.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPEMEMT
Not applicable.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a shoe press belt for making paper, and in particular, to a closed-type shoe press belt and a method for manufacturing the same.
2. Discussion of the Prior Art
The press part of a paper-making machine may be an open-type shoe press or a closed-type shoe press. Since the former open-type shoe press needs a larger installation space and has a drawback of oil scattering, the latter closed-type shoe press has been mainly used in recent years.
A closed-type shoe press is shown in FIG.
8
and FIG.
9
. In the drawings, reference numeral
21
designates a press roll, reference numeral
22
designates a shoe, and reference numeral
23
designates a shoe press belt. The shoe press belt
23
is formed in an endless shape and runs with an upper felt
25
and a lower felt
25
′ which pinch a wet paper sheet
24
, and the wet paper sheet
24
pinched between the felts is pressed by the press roll
21
and the shoe
22
to squeeze water from the wet paper sheet
24
.
The shoe press belt
23
described above is moved by a press roll
21
as a drive source via the felt
25
, the wet paper sheet
24
and the felt
25
′. When the shoe press belt
23
is moved, it is bent to the roll side at both edges of the shoe press belt
23
extending off from both edges of the press roll
21
, but it is deformed in a curve in an opposite direction in the part between edges
22
a
and
22
b
of the shoe
22
in the direction of MD, that is, in the part where it is pressed by the shoe
22
and the press roll
21
. Therefore, the complicated bending applies a compressive force and a tensile force to both ends of the shoe press belt
23
inside of and outside of the boundary at both ends of the shoe
22
in the direction of CMD.
That is, in the case where the shoe press belt
23
is moved in the direction of the arrows shown in
FIG. 9
, there is a pressed part
23
a
(shown by hatching) and an unpressed part
23
b
(shown by blank) and a drive force is applied to the pressed part
23
a
and the unpressed part
23
b
tends to lag. Therefore, this produces stress S at the boundary parts
23
c
of the belt
23
, which causes distortions and cracks.
A closed-type shoe press belt
23
having a short circumferential length (size) and hence severe usage conditions, as described above, needs to be durable, and hence is reinforced with a base fabric inserted into the thick portion of the belt. Typical examples of the closed-type shoe press belt are disclosed in Japanese Published Examined Patent Application No. 3-57236, Japanese Published Unexamined Patent Application No. 64-45888, Japanese Published Unexamined Patent Application No. 64-45889, Japanese Published Unexamined Patent Application No. 1-503315, Japanese Published Unexamined Patent Application No. 1-29892, Translation of Unexamined PCT Application No. 5-505428.
The Japanese Published Examined Patent Application No. 3-57236 discloses a shoe press belt made by mounting an endless base fabric around a mandrel and then by flowing resin thereon, that is, by a die molding method. This method has a merit of producing a uniform thickness and a smooth surface but has a problem in setting a position of the base fabric uniformity in the direction of thickness.
Further, the Japanese Published Unexamined Patent Application No. 64-45888 discloses a shoe press belt made by forming a first resin layer around a mandrel, then by putting a thermally contractible base fabric on the first resin layer, further by applying resin on the base fabric and by drying and curing the resin to form a second resin layer. This method can set a position of the base fabric uniformily in the direction of thickness, but since the base fabric used in this case is a fabric having an end, it is difficult to position the base fabric in the direction of MD and hence a pin hole might be produced.
Further, the Japanese Published Unexamined Patent Application No. 64-45889 discloses a shoe press belt made by mounting a not-yet-cured resin sheet around a mandrel, by putting a thermally contractible ground fabric on the resin sheet, further by winding a second not-yet-cured resin sheet on the base fabric, and finally by winding a ribbon made of thermally contractible resin on the second resin sheet and by thermally contracting the ribbon. Also in the case, as is the case with the Japanese Published Unexamined Patent Application No. 64-45888, since the base fabric used in this case is a fabric having an end, it is difficult to position the base fabric in the direction of MD and hence a pin hole might be produced.
Still further, the Japanese Translation of Unexamined PCT Application No. 1-503315 (U.S. Pat. No. 5,134,010) discloses a shoe press belt made by looping yarns in the axial direction of a mandrel around the whole periphery of the mandrel at constant intervals without using a fabric as a base fabric, by winding a yarn spirally thereon in the direction of MD, and then by flowing resin thereon. This method has a merit that a change in size caused by tension in the direction of CMD is made small, but has a problem that the yarns in a longitudinal direction and a yarn in the lateral direction constitute different layers and do not crimp the other yarn each other to reduce the flexibility of the base fabric and to change the center of bending in the direction of MD and in the direction of CMD, whereby bending stress applied by the bending to the obverse and reverse resin layers becomes large and trends to produce cracks at a part of the belt contacting the ends of the shoe.
Still further, the Japanese Published Unexamined Patent Application No. 1-298292, discloses a shoe press belt made by impregnating a mat-shaped fiber belt with not-yet-cured resin, by winding the fiber belt on a mandrel spirally, and by heating and curing the fiber belt. This belt has a problem that it is not stable in size in the direction of MD and in the direction of CMD and that it is apt to be separated.
Still further, the Japanese Translation of Unexamined PCT Application No. 5-505428 (U.S. Pat. No. 5,062,924) discloses a shoe press belt made by impregnating a fabric made of yarns, which have a low elastic modulus and are arranged in the direction of MD, and a yarn, which has a high elastic modulus and is wound in the direction of CMD, with not-yet-cured resin, by winding the fabric on a mandrel spirally, and by curing the fabric. This has a problem that the belt might be separated when stress is applied to a part where the fabric wound on the mandrel overlaps.
As described above, a shoe press belt and a reinforcing structure thereof produced by the conventional methods disclosed in the Japanese Published Examined Patent Application No. 3-57236 and others described above had a difficult problem that they could not show sufficient base material characteristics placing emphasis on durability required of the belt itself, and bending strength and tension in the direction of MD, which are required for a belt driven by a felt in range of the width of the belt in the direction of MD of a shoe.
SUMMARY OF THE INVENTION
The present invention has been made to solve the above problems, and it is an object of the present invention to provide a shoe press belt capable of increasing flexibility in bending in the direction of CMD and of effectively inhibiting cracks from being produced in the contacting the ends of a shoe, and a method for manufacturing the same.
In order to accomplish the above object, the present invention is formed of a first resin layer formed on a mandrel having a ground surface, a base material layer formed on the outer periphery of the first resin layer, and a second resin layer including the base material layer. The base material layer is formed of a composite layer including an inner layer in which at least one strand of yarn is wound spirally on the first resin layer in the circumfere
Ikeda Harushige
Inoue Hideo
Hastings Karen M.
Ichikawa Co. Ltd.
Quarles & Brady LLP
LandOfFree
Shoe press belt and method for manufacturing the same does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Shoe press belt and method for manufacturing the same, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Shoe press belt and method for manufacturing the same will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2436876