Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
DOCTORING DEVICE FOR PAP~M~RT~G MAC~INE
Field of the Invention
The present invention relates to a doctoring device
for use in association with machine rolls in pulp or
papermaking machines.
Backqround of the Invention
Pulp or papermaking machines, utilize machine rolls.
Such machine rolls are used during various aspects of
the process in, for example, the press, forming, drying
or calendering sections. The operation of machine rolls
requires a device to remove contaminants which form on
the roll surface and/or to pull off the sheet from them.
A traditional method of achieving this is through the
use of a mechanical device commonly referred to as a
doctor or doctor blade. The failure to remove the
contaminants or the sheet effectively can have a
catastrophic effect on the quality of the product being
produced.
The doctor blade is typically fastened to a
structural beam which is adjustably supported across the
papermaking machine on which a blade holder and
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replaceable blade is provided. The doctor blade comes
in direct contact with the roll surface so as to scrape
off any contaminants from the roll surface including the
whole pulp or paper web sheet or parts thereof. In
certain applications the material is very difficult to
remove. In this regard a second doctor blade in
addition to the first may be desireable to provide an
added scraping factor. This allows for the roll surface
to be scraped twice as much as it rotates~ In addition,
the space defined by the two blades provides a safe
location to apply a cleaning fluid on the roll surface
without contaminating or disturbing the pulp or paper
web nearby.
Heretofore the means of providing two blades on the
same machine roll is typically that illustrated in
figures 1 and 2. In figure 1 there is shown a machine
roll 1 having two separate and independent standard
doctor blade devices 2 and 3. This arrangement is quite
desireable since the doctor blades may be independently
adjusted with respect to the roll. Furthermore, if
there is sufficient space in between the two devices
each would be able to scrape the contaminants, sheet or
web from the roll and deflect it away, down to a broke
pit or to a safe location outside the process. In
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addition, such a design permits easy access for cleaning
and maintenance of the blades, the blade holders and
support structure. However, while such an arrangement
has certain desirable features, it also has a
significant drawback, that being in existing papermaking
machines or in the design of new machines there simply
is not enough room to install a complete and independent
second doctor blade unit.
Another method of incorporating a second doctor blade
on the same pulp or paper machine is shown in figure 2.
Again a standard machine roll 4 is illustrated. To sa~e
space, a second blade 7 and blade holder 8 is added
trailing the first blade 5 and blade holder 6 all of
which is supported by a single solid structure 9 which
may be of conventional construction. The problems with
this design are many. The scrapings removed by the
second blade fall back and accumulate on the support
structure 9 in the closed space created in between the
blades. During the operation of the machine, this area
can not be cleaned and will eventually not only impede
the effective operation of the blades but also it is
possible that the high speed web will become stuck
between the two blades and force the structure to bend
away from the machine roll causing immediate damage to
it.
Accordingly, there exists a need to provide for a
doctor blade arrangement utilizing two doctor blades
which has the advantages of the foregoing arrangements
yet avoids their disadvantages.
Summary of Invention
It is therefore a principle object of the invention
to provide for an improved doctoring device for the
machine roll in a pulp or papermaking machine which is
simple yet effective and which avoids the disadvantages
of prior art devices.
In this regard, the present invention is directed
towards providing a doctoring device which includes two
doctor blades in engagement with the machine roll of a
pulp or papermaking machine. The blades are placed in
successive contact with the machine roll and provide a
more thorough cleaning thereof. In this regard, the
first doctor blade is supported by way of a typical
support structure common in the industry. The second or
leading doctor blade is placed ahead of the first (with
respect to the direction of rotation of the machine
roll) and is attached to the main structure of the first
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blade. The second blade is positioned by way of widely
spaced gussets and the blade holder may be flexible or
rigid design depending upon the application. In
addition the second blade assembly is separately
adjustable with respect to the first blade assembly.
The maintenance and positioning of the blade arrangement
provides all the advantages of two doctor blade support
structures as shown in figure 1 without the
disadvantages of the single rigid structure as shown in
figure 2. In this regard, full adjustability of both
doctor blades is realized and an opening there between
is provided for the scrapings or the sheet to pass
through. Also, the wide spacing provides room to place
a cleaning fluid showering device if desired in addition
to preventing the accumulation of dirt while providing
ease of cleaning and maintenance. In case of potential
malfunctioning of the leading blade, the high speed web
will be removed by the second blade and can exit between
the two blades, thus providing reaction time for the
operator to take corrective action thereby adding a
safety factor to the operation. Should however the
sheet become stuck between the two blades, the leading
doctor blade will be damaged first since it is the
weakest. It can be removed and replaced. Furthermore,
the machine will still be operational with the leading
blade removed since the first blade remains providing
for standard one blade operation.
Brief DescriPtion of the Drawin~
Thus the objects and advantages of the invention will
be realized, the description of which should be taken in
conjunction with a view of the drawings wherein:
Figures 1 and ~ depict prior art arrangements
previously discussed;
Figure 3 depicts a somewhat schematic side view of
the two blade doctor arrangement incorporating the
teachings of the present invention; and
Figure 4 is an isometric view of the two doctor blade
arrangement showing the supporting members for the second
doctor blade, incorporating the teachings of the present
nvent~on.
Detailed Deqcription of the Preferred Embodiment
Turning now more particularly to figure 3, there is
shown a portion of a machine roll 10 used in a pulp or
papermaking machine. This machine roll 10 may be that
used in for example the press, forming, drying or
calendering sections of a pulp or papermaking machine or
with other machine rolls used in the process. The
machine roll 10 may be cylindrical, crowned or of other
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configuration suitable for purpose having an outer
surface 12 which may be smooth, rough (i.e. granite
which is relatively rough) etc., depending upon the
application in which it is being used. The machine roll
10 in figure 3 would be rotating in a clockwise
direction.
Positioned adjacent the roll 10 is the doctor blade
assembly, generally indicated by the numeral 14. The
assembly 14 comprises a main support structure 16 which
may be of typical construction common in the industry.
The support structure 16 ser~es to support the doctor
blades which are in contact with surface 12 along the
length of the roll 10, as will be discussed.
In this regard, coupled to structure 14 is a plate 1
which runs across the pulp and paper machine adjacent
roll 10. Plate 18 terminates at an angled surface 20
which is positioned approximately 1 inch from surface 12
of the machine roll 10.
Mounted on plate 18 is a doctor blade holder 22 which
serves to support a detachable doctor blade 24. The
doctor blade 24 and holder 22 may be of the type
commonly used in the industry. This may for example be
of the type manufactured by Albany International, Corp.
assignee herein Model No. KF-35, XF-35A or PNEUFLEX~
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which can be of rigid or flexible design depending upon
application. Doctor blade 24 is removable and therefore
replaceable when worn out. The position of support 16
is adjustable in relation to roll 10 to adjust the
position of blade 24. Holder 22 may be adjustable in
nature to further adjust the position of blade 24 and to
properly bias it with respect to the roll 10. Doctor
blade 24 is shown engaging the surface 12 at
approximately a 30 angle thereto and runs the length of
the roll 10. This angle can vary considerably depending
upon the needs of the particular application.
A leading edge doctor blade assembly 26 is provided
upstream of blade 24. This assembly 26 includes widely
spaced gussets 28 (one shown) mounted along support
structure 16 (for example on the order of 48") via
mounting bolts 30 which allow the removal of the
assembly 26 for repair or replacement or the shimming of
assembly 26. The mounting arrangement may include slots
in the gussets 28 and an accompanying jack screw
assembly 32 to further adjust its position.
Coupled to the gussets 28 is a support plate 34 which
supports a second doctor blade holder 36. Plate 34
similarly terminates at an angled surface 38 positioned
approximately 1 inch from surface 12. Doctor blade
holder 36 serves to support the second doctor blade 40
which is detachable therefrom for repair or replacement.
Again blade 40 and holder 36 as aforesaid may be of the
type commonly used in the industry. Holder 36 may be
adjustable in nature to further adjust the position of
blade 40 and properly bias it. The blade 40 is shown
engaging surface 12 at an angle of 30 and runs the
length of the roll 10. The angle of contact again can
vary considerably depending on the application involved.
In addition, for the scraping off of the sheet from the
roll, sheet slitters which may be high pressure jets,
generally indicated by numeral 42, that slit the sheet
ahead of the gussets may be incorporated possibly
mounted on or adjacent or ahead of the gussets 28 and/or
support plate 34 or at any other location suitable for
purpose.
The relative position of the blades 24 and 40 is
shown just by way of example at respective angles of 30
and 45 (15 apart) with respect to perpendicular line
44 other angular placement may of course be utilized
depending upon the particular application as long as
sufficient spacing is achieved between the blades (i.e.
6"-12"). This serves to illustrate the spacing between
the blades which provides ample room to allow the
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scraped material to fall through or the sheet to pass
therebetween. This not only prevents the accumulation
of dirt but also allows the positioning of a cleaning
fluid showering device if so desired. Such a showering
device 46 may be mounted on blade holder 22 and includes
a feed pipe having a plurality of nozzles for spraying
the roll 10 which not only assists in the removal of the
scrapings (which are generally sticky) but also serves
to lubricate the roll 10. Such spraying further allows
for easy maintenance. Should for some reason the second
blade assembly 26 become damaged it can be removed and
replaced. Should replacement be delayed, the pulp or
paper machine could still operate with the single
standard doctor blade.
Thus by the present invention, its objects and
advantages are realized and although a preferred
embodiment has been disclosed and described in detail
herein, its scope should not be limited thereby rather
its scope should be determined by that of the appended
cla~ms.
