Coating processes – Restoring or repairing – Metal article
Reexamination Certificate
2002-05-07
2003-05-27
Beck, Shrive P. (Department: 1762)
Coating processes
Restoring or repairing
Metal article
C427S140000, C427S230000, C162S199000, C162S272000, C277S356000, C277S316000, C277S314000, C277S936000, C277S938000, C277S946000, C285S014000, C285S015000, C285S047000, C285S294100, C285S296100
Reexamination Certificate
active
06569493
ABSTRACT:
BACKGROUND OF THE INVENTION
1 Field of the Invention
This invention relates to a method of repairing the moisture barrier separating a paper machine dryer drum from the dryer journal. Such processes of this type, generally, involve substantially filling the air cavity between the dryer steam intake pipe and the dryer journal with a flowable moisture barrier.
2 Description of the Prior Art
In conventional paper making machines several large dryer drums or heated cylinders are located near the end of the paper machine. The dryer drums are conventionally filled with steam at approximately 200 to 300 F degrees under pressure. The dryer drums contact both sides of the paper web and reduce the paper's water content to approximately 5%. The dryer drums are typically 5 feet wide or wider and typically weigh in excess of 2 tons. Each drum end is supported by a journal head. Each journal head is further supported by a journal assembly at each end.
FIG. 1
is a cross-sectional drawing of a prior art journal assembly
2
. The journal assembly
2
acts as an axle to rotate the dryer drum (not shown) about a central axis. The journal assembly
2
typically has a hollow, annular main journal body
3
, hereinafter referred to as the journal. The journal
3
is supported by and rotated via journal bearings
4
. The bearings
4
are typically located in a housing. U.S. Pat. No. 4, 716, 661 by Asman is an exemplary reference of a hollow, annular journal for a paper machine dryer. Typically the dryer drum steam intake pipe
12
is placed into the hollow portion of the journal
3
as shown in FIG.
1
. Typically, steam enters into the dryer drum in the direction of arrow A. Typically a steam condensate pipe
8
is located internal to the steam intake pipe
12
. In such cases, the steam condensate exits the dryer drum in the direction of arrow B.
A thin annular cavity
16
separates the dryer steam intake pipe
12
from the journal
3
. This air cavity, primarily, serves as a heat insulator between the dryer steam intake pipe
12
and the journal
3
. The cavity eliminates most heat transfer from the steam intake pipe
12
to the journal bearings
4
.
Conventionally a journal moisture barrier
20
is used to prevent steam from leaving the dryer drum and entering the cavity
16
. Typically, the journal moisture barrier
20
is an annular flange with a polymeric coating-based material or other moisture barrier, such as a rubber gasket. The journal moisture barrier is typically secured to the journal
3
by bolts
21
so that the polymeric coating touches the journal
3
. However, conventional journal moisture barriers
20
often fail to withstand the high temperatures of the dryer steam that can reach as high as 390° F. Frequently, the journal moisture barrier
20
breaks down or develops a leak that allows moisture from the dryer drum to enter the cavity
16
. As high temperature moisture enters the cavity
16
unacceptable amounts of heat are transferred through the journal
3
to the journal bearings
4
. High temperature moisture leaks adversely impacts the journal
3
and the bearings
4
. The moisture can cause the journal's
3
metal surface too pit and can breakdown the bearing's
4
lubrication (not shown) and lubrication system (not shown). Typically a leak in the journal moisture barrier
20
is detected by moisture exiting the cavity
16
via an opening
14
, such a weep hole.
It is known to replace conventional journal moisture barriers
20
when they break down or leak. However, this requires many man-hours of labor and downtime for the entire paper machine to replace one moisture barrier, which ultimately leads to reduced paper production. An exemplary description of a conventional replacement or repair method is described in U.S. Pat. No. 4, 716, 661, column 4, lines 55-70. A typical paper machine includes many dryer journal moisture barriers
20
so the potential maintenance cost and paper machine downtime is great. Also, simply replacing one conventional journal moisture barrier
20
with another does not eliminate future replacements. Therefore, a more advantageous repair method for damaged journal moisture barriers
20
is highly desirable.
It is apparent from the above that there exists a need in the art for a method to quickly and cost effectively repair a paper machine dryer journal moisture barrier. It is a purpose of this invention to fulfill this and other needs in the art in a manner more apparent to the skilled artisan once given the following disclosure.
SUMMARY OF THE INVENTION
Generally speaking, this invention fulfills these needs by providing a method to repair a moisture barrier separating a paper machine dryer drum from the dryer journal. The air cavity located between the dryer steam intake pipe and the dryer journal is filled with a flowable moisture barrier. The flowable moisture barrier in the cavity seals any leaks in the journal moisture barrier.
The above and other advantages, features and benefits of the present invention will become more apparent by considering the following detailed description and drawings.
REFERENCES:
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patent: 3097994 (1963-07-01), Dickens et al.
patent: 3685546 (1972-08-01), Sigmund
patent: 3875686 (1975-04-01), Smoot
patent: 4069596 (1978-01-01), Sisler
patent: 4076582 (1978-02-01), Burkhart
patent: 4348819 (1982-09-01), Gamble
patent: 4707222 (1987-11-01), Müllner et al.
patent: 4716661 (1988-01-01), Asman
patent: 4834884 (1989-05-01), Berglöff et al.
patent: 4915787 (1990-04-01), Branyon et al.
patent: 4975150 (1990-12-01), Yasuda et al.
patent: 5154009 (1992-10-01), Kade et al.
patent: 5360519 (1994-11-01), Scarano
patent: 5363569 (1994-11-01), Kadakia
patent: 5463883 (1995-11-01), Pellerin et al.
patent: 5554263 (1996-09-01), Laakko
patent: 5843282 (1998-12-01), Schmitt et al.
patent: 5900120 (1999-05-01), Graf
patent: 6095784 (2000-08-01), Wickizer
Beck Shrive P.
Bowman D. L.
Kolb Michener Jennifer
Mead Westvaco Corporation
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