U.S. patent application number 14/694619 was filed with the patent office on 2016-05-19 for doctor device for fiber web machine and doctor arrangement in fiber web machine.
This patent application is currently assigned to Valmet Technologies, Inc.. The applicant listed for this patent is Hannu Eerikainen. Invention is credited to Hannu Eerikainen.
Application Number | 20160138223 14/694619 |
Document ID | / |
Family ID | 53396139 |
Filed Date | 2016-05-19 |
United States Patent
Application |
20160138223 |
Kind Code |
A1 |
Eerikainen; Hannu |
May 19, 2016 |
Doctor Device For Fiber Web Machine And Doctor Arrangement In Fiber
Web Machine
Abstract
A doctor device includes blade devices (19) supported on holder
devices (23). The holder devices (23) are for arranging the blade
devices (19) in a fiber web machine to be placed in connection with
a doctor blade (18) equipped with a blade holder (38). The blade
devices (19) are supported aligned in a circumferential direction
with edge areas (20) of the doctor blade (18). The holder devices
(23) are arranged to be fastened in connection with the blade
holder (38) so that the blade devices (19) extend further out than
the doctor blade (18) to reduce the wear of the doctor blade
(18).
Inventors: |
Eerikainen; Hannu; (Varkaus,
FI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Eerikainen; Hannu |
Varkaus |
|
FI |
|
|
Assignee: |
Valmet Technologies, Inc.
Espoo
FI
|
Family ID: |
53396139 |
Appl. No.: |
14/694619 |
Filed: |
April 23, 2015 |
Current U.S.
Class: |
162/281 |
Current CPC
Class: |
D21G 3/04 20130101; D21G
3/005 20130101 |
International
Class: |
D21G 3/00 20060101
D21G003/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 1, 2014 |
FI |
20145316 |
Claims
1-13. (canceled)
14. A doctor device for a fiber web machine having a roll with a
cylindrical surface to be doctored which roll defines a
circumferential direction along which the roll rotates, a doctor
blade (18) engageable with the roll cylindrical surface, wherein
the doctor blade (18) is mounted in a first doctor blade holder to
a doctor beam which extends in a cross machine direction, the
doctor blade having in the cross machine direction, a first end
edge and a second end edge, and a middle between the first end edge
and the second end edge, wherein an outward direction is defined
between the middle and the first end edge and between the middle
and the second end edge, the doctor device comprising: two blade
devices (19), wherein each blade device is mounted to a holder
device (23) which is arranged to fastened one of the blade devices
to the first blade holder (38) of the doctor blade (18); wherein
the holder devices (23) are arranged to be connected to the doctor
beam (38) aligned with an edge area containing one of the first end
edge and the second end edge of the doctor blade (18); wherein the
holder devices (23) are arranged to be fastened to the blade holder
(38) so that a portion of each blade device is further out in the
outward direction than the doctor blade (18); and wherein each
blade device when mounted to the first blade holder extends further
out than the doctor blade so that the blade devices are positioned
to engage the roll before the doctor blade in the circumferential
direction.
15. The doctor device of claim 14 wherein the each of the holder
devices (23) includes a support structure (24) which has connecting
devices for fastening to the doctor beam (17).
16. The doctor device of claim 14 wherein each of the holder
devices has two ends, and further comprising a support structure
(24) fastened to one end of the holder devices, wherein the support
structure has connecting devices for fastening to the doctor beam
(17).
17. The doctor device of claim 14 wherein the two holder devices
(23) are symmetrical about a plane passing between said two holder
devices.
18. The doctor device of claim 14 wherein the holder devices define
a length of 800 to 1,200 mm in the cross machine direction.
19. The doctor device of claim 15 further comprising adjusting
devices (31) between the holder devices (23) and the support
structures (24).
20. A doctor arrangement in a fiber web machine having a roll to be
doctored, the roll defining an axis along which the roll is
supported to rotate and along which the roll extends to define a
roll width, the axis defining an axial direction, and the roll
defining a circumferential direction of rotation of the roll, the
doctor arrangement comprising: a doctor blade (18) which extends
essentially across the entire roll width, wherein the doctor blade
has in the axial direction a first end edge and a second end edge;
two blade devices (19) each of which is separate from the doctor
blade (18), wherein each blade device is arranged aligned with an
edge area containing one of the first end edge and the second end
edge; and wherein the blade devices and the doctor blade are
arranged so that with respect to the cylindrical surface which the
blade devices and doctor blade are arranged to engage, the blade
devices (19) are arranged before the doctor blade (18) in the
direction of rotation of the roll (16).
21. The doctor arrangement of claim 20 further comprising a doctor
beam, and wherein the blade devices (19) are supported to the
doctor beam (17) to which the doctor blade is supported by
fastening devices.
22. The doctor arrangement of claim 20 wherein the fiber web
machine has a coating station (22) and wherein the roll (16) is a
drying cylinder (21) which is placed after the coating station in
the fiber web machine.
23. The doctor arrangement of claim 20 wherein the blade devices
(19) extend beyond the edge areas (20).
24. The doctor arrangement of claim 23 wherein the blade devices
(19) define a length and 40 to 60 percent of the length of the
blade devices (19) extends beyond the edge areas (20).
25. The doctor arrangement of claim 21 wherein each blade device
(19) includes a support arm (28) which is fastened to the doctor
beam (17) using at least some of the fastening devices (34) that
support the doctor blade (18).
26. A doctor arrangement for a fiber web machine having a coating
station and a dryer roll having a cylindrical surface arranged
after the coating station, the dryer roll defining a
circumferential direction along which the dryer roll rotates; the
doctor arrangement comprising: a main doctor blade (18), wherein
the main doctor blade (18) is supported in a first blade holder
(38) which is mountable to a doctor beam which extends in a cross
machine direction; wherein the main doctor blade has in the cross
machine direction, a first end edge and a second end edge, and a
middle between the first end edge and the second end edge, wherein
an outward direction is defined between the middle and the first
end edge and between the middle and the second end edge; two short
doctor blades each of which is shorter than the main doctor blade
(18) and each short doctor blade is supported in a holder device
which is arranged to fasten one of the short doctor blades to the
doctor beam (18); wherein the short doctor blades and the main
doctor blade are arranged so that with respect to the cylindrical
surface to which the blade devices and doctor blade are arranged to
engage, the short doctor blades (19) are arranged before the main
doctor blade (18) in the circumferential direction of rotation of
the roll (16); wherein the holder devices (23) are arranged
supported on the doctor beam aligned with an edge area containing
one of the first end edge and the second end edge of the doctor
blade (18); wherein the holder devices (23) are arranged to be
fastened to the doctor beam so that a portion of each short doctor
blade is further out in the outward direction than the main doctor
blade (18); and wherein each short doctor blade extends further out
than the main doctor blade so that the short doctor blades are
positioned to engage the dryer roll before the main doctor blade in
the circumferential direction.
27. The doctor arrangement of claim 26 wherein the main doctor
blade is supported on the doctor beam by fastening devices.
28. The doctor arrangement of claim 26 wherein the short doctor
blades extend beyond the edge areas in the outward direction.
29. The doctor arrangement of claim 26 wherein the short doctor
blades define a length, and 40 to 60 percent of the length of the
short doctor blade extends beyond the edge areas in the outward
direction.
30. The doctor arrangement of claim 27 wherein each holder device
includes a support arm which is fastened to the doctor beam using
at least some of the fastening devices that support the main doctor
blade.
Description
CROSS REFERENCES TO RELATED APPLICATIONS
[0001] This application claims priority on Finnish No. 2013, filed
Apr. 1, 2014, the disclosure of which is incorporated by reference
herein.
STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSORED
RESEARCH AND DEVELOPMENT
[0002] Not applicable.
BACKGROUND OF THE INVENTION
[0003] The invention relates to a doctor device for a fiber web
machine, which doctor device includes blade devices and holder
devices for arranging the blade devices in a fiber web machine to
be placed in connection with an adapted doctor blade equipped with
a blade holder to the edge areas of said doctor blade. The
invention also relates to a doctor arrangement in a fiber web
machine.
[0004] Finnish patent number 110705 (U.S. Pat. No. 6,749,724)
presents an arrangement in a fiber web machine. The arrangement is
intended for the so-called wet end of a fiber web machine, where
material such as fibers and fillers adhere to the rolls from the
moist web and especially from its edges. Accumulations of this kind
result in, among other things, the web sticking to the roll
surface, which increases web breaks and thus disturbs production.
The patent suggests that short blade devices be placed after the
doctor blade that is supported to a blade holder, which blade
devices enhance the doctoring efficiency of the arrangement at the
edges of the doctor blade, i.e. at the edge areas.
[0005] In practice, it is challenging to place a prior art
arrangement in the fiber web machine. In fact, the above-mentioned
patent describes the arrangement only in principle, without any
holder devices for the blade devices. Moreover, the arrangement is
unsuited to other locations such as the finishing section, where
local fouling of a roll also occurs. As an example, after coating
some coating slip accumulates on the surface of a roll, especially
at the edge areas of the doctor blade. In such a position, the
doctor blade of the application presented in said patent would wear
rapidly and unevenly in the same way as a doctor blade currently
wears in said position. In this case, streaks remain on the surface
of the roll especially at the edge areas, and the streaks remain
visible in the end product, too. Moreover, a worn doctor blade
needs to be replaced frequently, which causes extra costs. In
practice, the fiber web machine must be stopped for the duration of
the replacement of the doctor blade, which shortens the efficient
production time.
SUMMARY OF THE INVENTION
[0006] The object of this invention is to accomplish a new type of
a doctor device for a fiber web machine, which doctor device can be
used for intensifying the efficiency of the doctor arrangement and
at the same for reducing the uneven wear of the doctor blade.
Another object of the invention is to accomplish a new type of a
doctor arrangement for a fiber web machine, where the doctoring
efficiency of the doctor arrangement is better than previously and
where the replacement interval of the doctor blade is longer than
previously. A characteristic feature of the doctor device according
to the invention is that the holder devices are arranged to be
fastened in connection with a blade holder so that the blade
devices are further out than the doctor blade. Correspondingly, a
characteristic feature of the blade arrangement according to the
invention is that the blade devices are arranged before the doctor
blade in the direction of rotation of the roll. In practice, the
blade devices remove a significant portion of the material at the
edge areas of the doctor blade even before the doctor blade. In
this case, the short blade devices wear, but the costs caused by
their replacement are considerably smaller than the cost of
replacement of a full-length doctor blade. Moreover, the blade
devices can be serviced even during production. In this way, it is
possible to avoid quality deviations in the end product and to
achieve as uninterrupted production as possible.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] The invention is described below in detail by making
reference to the enclosed drawings that illustrate an embodiment of
the invention.
[0008] FIG. 1 shows the finishing section of a fiber web
machine.
[0009] FIG. 2a shows a doctor arrangement according to the
invention.
[0010] FIG. 2b shows a partial magnification of FIG. 2a.
[0011] FIG. 3a shows a doctor arrangement according to the
invention seen from the tending side diagonally from the back.
[0012] FIG. 3b shows the doctor arrangement of FIG. 3a seen
diagonally from the front.
[0013] FIG. 3c shows a doctor arrangement according to the
invention seen from the drive side diagonally from the front.
[0014] FIG. 4a shows a doctor arrangement according to the
invention seen against the machine direction.
[0015] FIG. 4b shows the doctor arrangement of FIG. 4a seen in the
machine direction.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0016] FIG. 1 shows a finishing section of a fiber web machine
which is known as such. Only the last drying cylinder 11 is
presented of the dryer section that precedes the finishing section.
The web forming machines are usually paper or board machines. The
consecutive production sections shown in FIG. 1 are--in addition to
the dryer section 10--pre-calendering 12, coating 13 and
calendering 14, after which the finished web is reeled with the
reel 15. This application represents so-called online finishing,
where the web is fed from the dryer section directly to finishing
without re-reeling. In order to minimize production losses, it is
important to have disturbance-free production from the wet end to
the reel.
[0017] Marked with X in FIG. 1 are example positions where the
doctor arrangement according to the invention is preferably used.
Generally speaking, roll 16 of FIG. 2a included in the fiber web
machine is equipped with the doctor arrangement. The doctor
arrangement includes a doctor blade 18, which is here supported to
the doctor beam 17 arranged in connection with the roll 16 (FIG.
2a). The doctor blade is primarily used for keeping the surface of
the roll clean, but in certain positions it is also used for
guiding the web into a pulper in a web break situation. The doctor
beam extends essentially across the width of the entire roll, and
it is usually supported by bearings at both ends. By turning the
beam 17, the doctor blade 18 can be placed against the surface of
the roll 16 and also away from it. The beam 17 can potentially also
be moved in the axial direction.
[0018] The doctor arrangement also includes blade devices 19 which
are separate from the doctor blade 18 and which are arranged at
both edge areas 20 of the doctor blade 18 (FIGS. 4a and 4b). In
practice, the edge areas of the doctor blade correspond to the edge
areas of the roll. In the most challenging position, the roll 16 is
a drying cylinder 21 (indicated in FIG. 1), which is placed after a
coating station 22 included in a fiber web machine. The surface of
the drying cylinder is hot, which contributes to the sticking of
the coating slip. The doctor arrangement according to the invention
works in this position, too, and remains operational for a longer
period than previously.
[0019] The coating slip contains substances such as kaolin, calcium
carbonate or talc. These are very abrasive substances. Moreover,
they accumulate easily on the surface of the roll, which makes the
above-described doctor positions demanding. Doctor blades made even
completely of carbon fiber are used in prior art arrangements. Such
doctor blades are hard and endure wear, but they are expensive.
Despite their wear-resistance, the doctor blades wear unevenly, so
their replacement intervals are short.
[0020] This is why in the invention the blade devices 19 are
arranged before the doctor blade 18 in the direction of rotation of
the roll 16. In this way, the blade devices 19 first touch the
material that has accumulated on the surface of the roll. In this
case, most of the wear impact is directed at the blade devices,
while the actual doctor blade 18 is worn less. The doctor blade
consequently wears more evenly than previously, which extends the
service life of the doctor blade and reduces its need for
replacement. At the same time, the material can be removed more
efficiently from the surface of the roll 16.
[0021] FIG. 2a shows the roll 16 in part only. Correspondingly,
FIG. 2b illustrates a prior art doctor blade 18 and doctor beam 17
with a broken line, and the doctor device according to the
invention is illustrated with a solid line. The doctor device is
intended for a fiber web machine, and it includes blade devices 19
and holder devices 23. The holder devices 23 are intended for the
placement of the blade devices 19 in connection with the doctor
blade 18 included in the fiber web machine, to the edge areas 20 of
said doctor blade 18. In the invention, the holder devices 23 are
arranged to be fastened in connection with the blade holder 38 so
that the blade devices 19 are further out than the doctor blade 18.
With respect to the fastening point of the doctor blade, the blade
devices extend further out than the doctor blade, both in the blade
direction and radially.
[0022] With respect to the roll, the holder devices 23 are thus
arranged for the placement of the blade devices 19 before the
doctor blade 18 in the direction of rotation of the roll 16. In
this case, by means of the holder devices 23 the doctor device can
be placed in connection with the doctor blade 18 so that the blade
devices 19 are located before the doctor blade. In the invention,
the blade devices 19 are also preferably supported to said doctor
beam 17. In other words, the holder devices 23 include a support
structure 24, which has connecting devices 34' for fastening to the
doctor beam 17 arranged to support the doctor blade 18. In this
case, the blade devices can be simply added to an existing doctor
arrangement, and to put it more precisely, by fastening the
connecting devices to the doctor beam.
[0023] FIGS. 3a to 3c show one end of the doctor arrangement at a
time. The holder devices 23 according to the invention include a
blade holder 26, which is fastened to a support strip 27. The
support strip 27 is at least as long as the blade holder 26. The
blade holder as such can be different from that presented, but here
the applicant's own model provided with one loading hose has been
used.
[0024] The supporting of the blade devices is also of a new type:
the support structure 24 is fastened to one end of the holder
devices 23. In other words, the holder devices are supported in a
projection-type manner, whereby the operation of the doctor blade
18 remains unchanged. In the application presented, each blade
device 19 includes a support arm 28. Here, the support arm 28 is
connected to the support strip 27 by means of two connectors 29.
There can also be more numerous connectors, or some other
applicable support structure is used in the supporting. The
fastening is carried out by means of two pairs of bolts 30, for
which bolts there are elongated holes 37 in the support strip 27.
In this case, the support strip 27 can be adjusted with respect to
the support arm 28. More generally speaking, there are adjusting
devices 31, shown in FIG. 2b, between the holder devices 23 and the
support structure 24. Adjustment is needed primarily in the
installation of the doctor device. During operation, the blade
devices are loaded by means of a loading hose 32 shown in FIG.
2b.
[0025] The installation of the doctor device according to the
invention in connection with the doctor blade has been designed to
be especially easy. In the invention, as shown in FIGS. 3a-3b the
blade devices 19, more precisely the support arm 28, is fastened to
the doctor beam 17 using the same fastening devices 34 that support
the doctor blade 18. In other words, there is a similar hole pitch
33 in the support arm 28 for the fastening devices 34 as in the
doctor holder 38 of the doctor blade 18. In this way, the doctor
device can be fastened as long as bolts 34' that are longer than
normally are used at the support arm 28. In FIG. 3c, there are six
such bolts, only two of which are illustrated.
[0026] It has also been possible to keep the manufacturing costs of
the doctor device at a reasonable level. The holder devices 23
according to the invention are symmetrical. In other words, there
are almost identical blade holders at both ends of the roll, while
the support arms 28 of the doctor devices are minor images of each
other. In this case, spare parts such as a short doctor blade 35
can be used at either end. The symmetrical design is illustrated
especially in FIG. 4a, where the doctor arrangement is viewed
against the machine direction. At both ends of the short blade
holder 26, there is a finger plate 36 by which the blade holder 26
can be moved. Moreover, the support strip 27 has two sets of
elongated holes 37 for fastening to the support arm 28 as shown in
FIG. 3a. There are also compressed air connections at both ends of
the loading hose 32, and compressed air supply is connected to the
outermost of these connections. In this case, the doctor
arrangement can be composed of standard components by arranging two
doctor devices according to the invention in connection with an
existing doctor blade, on the same doctor beam.
[0027] FIGS. 4a and 4b might suggest that the blade devices 19 are
unnecessarily long. In practice, the length of the holder devices
23 is 800 to 1,200 mm. Moreover, the blade devices 19 extend
clearly beyond the edge areas 20. In practice, 40 to 60 percent of
the length of the blade devices 19 extends beyond the edge areas
20. In this case, the finger plate 36 extends to a safe distance
from the roll. In other words, the blade holder can be moved by the
finger plate also during production. This is why, if the short
doctor blade wears locally, it can be moved somewhat manually,
whereby the best doctoring result can be achieved at the most
critical location. Moreover, the moving is possible without a
safety risk. By depressurizing the loading hose and, if necessary,
by using vacuum, the short doctor blade can be detached from the
surface of the roll and hence the blade holder can be moved. If
necessary, the entire blade holder with the doctor blade can be
pulled off for service and replacement. The part beyond the roll
can also be utilized by exchanging the short doctor blades on the
tending and drive sides with each other. In this way, even a short
doctor blade can be utilized over its entire length. In the same
manner, parts of the doctor blade 18 that have worn unevenly can be
removed, and it can be used for reconditioning several short doctor
blades 35. As an example, the width of a roll is currently from 4
to 10 meters, while the length of the blade devices according to
the invention is from approximately 0.5 meters to approximately 1
meter.
[0028] Above is a description of one example of a doctor device
according to the invention and of its utilization in a doctor
arrangement. Generally speaking, the doctor device according to the
invention comprises a first blade holder 26, which is short. A
short doctor blade 35 is supported to this short blade holder 26.
The short doctor blade 35 constitutes part of the blade devices 19.
Both the short blade holder and the short doctor blade extend over
only a part of the width of the roll surface to be doctored,
preferably over its edge areas. The doctor blade 18 included in the
doctor arrangement and the blade holder 38 that supports the doctor
blade 18 extend essentially over the entire width of the roll to be
doctored.
[0029] The doctor device according to the invention is simple and
compact. Components proven in practice can be applied to it. If
necessary, for example the blade holder is reinforced to increase
the load resistance. The doctor device can be placed in connection
with various types of doctor blades. Two doctor devices can be used
for updating a doctor arrangement quickly to a new level. In this
way, the doctoring result is improved even though the replacement
interval of the doctor blade extends at the same time. The
effective production time is thus maximized while at the same time
minimizing the maintenance costs. In conjunction with the
installation of doctor devices, a modern blade holder with a new
type of doctor blade is preferably replaced in the doctor beam. In
this way, the overall doctoring result of the doctor arrangement is
improved and serviceability is facilitated.
* * * * *