Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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ROLL CLEANING APPARATUS
Field of the Invention
The present invention relates to methods and apparatus for cleaning rolls.
Background of the Invention
Many industrial processes use rolls to either treat or form a web of material.
Typical of
such applications is the papermaking process, in which, at various stages of
the process the web
of paper is passed between a nip or entrained about one or more rolls. During
such a process, the
rolls may pick up material from the web and thus contaminate the surface of
the roll. Such
contamination can lead to reduction in the quality of the process and may
result in unsatisfactory
material being produced.
It has previously been suggested to remove material from the roll by the
application of a
doctor blade against the roll surface. A doctor blade is a thin blade that
scrapes the surface and
removes the material. However, in practice it is found that the blade may not
be effective to
remove all the surface contamination and eventually the contamination will
build up to impair
the performance of the process. For example, in a papermaking process, it may
be that rolls in a
calendar stack are heated. Heating is sometimes used when papers of particular
chemical
compositions, such as, for example, relatively high clay or starch content and
gloss finish are
being produced. The warmth of the roll may tend to increase the tendency for
clays, starch or
other materials to build up on the rolls. In any case, it may be desirable to
prevent or discourage
the agglomeration of clays or other matter on the rolls.
SUMMARY OF THE INVENTION
In general terms, the present invention provides a pad that can engage the
periphery of
the roll over a limited extent of the circumference. The pad is formed with a
scouring surface
that may tend to remove contaminants from the surface. The pad is mounted on a
support that
can be pivoted into and out of engagement with the roll. The support is biased
to provide a
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relatively uniform pressure of the pad against the surface of the roll and
thereby to clean the
surface.
In another feature, the scouring head may be pivotally supported to permit the
pad to
conform to the surface of the roll as it is brought into engagement. The
support may be biased
into engagement with the roll by a compressible fluid. In another feature, the
pad may be caused
to oscillate axially relative to the surface of the roll while the roll is
turning.
In another feature, the apparatus has a cleaning member operable to engage the
roll while
the roll is revolving, and a carrier. The cleaning member is mounted to the
carrier. The carrier is
mounted to present the cleaning member to the roll. The cleaning member is
movable between a
first position in which the cleaning member engages the roll, and a second
position in which the
cleaning member is located clear of the roll. The cleaning member has a
contact region having
both axial and circumferential extent. The contact region is flexible in the
radial direction. In
another feature, the cleaning member has a roll contacting interface element,
and the roll contact
interface element is operable at temperatures in excess of 160 F. In a further
feature, the
cleaning member has a roll contacting interface element that is operable at
temperatures in
excess of 200 F, and which temperatures may be in the range of 250 - 300 F. In
still another
feature, the cleaning member is axially displaceable relative to the roll
while in contact with the
roll and while the roll is revolving.
In a further feature, the roll cleaning apparatus has a drive connected to
impart
reciprocating axial motion to said cleaning member. In yet another feature,
the carrier is
movably mounted relative to the roll, and is constrained to cause said
cleaning member mounted
thereto to move in a manner having a non-zero radial component of displacement
relative to the
roll. In a still further feature, the carrier is pivotally mounted, and is
pivotally movable about an
axis running parallel to said roll. In another feature, the cleaning member
has a circumferentially
extending surface conforming to the roll, and the cleaning member has a degree
of freedom of
motion permitting the circumferentially extending surface to self-center on
the roll.
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In another feature, the cleaning member includes a self-centering shoe. There
is also a
feature in which the roll cleaning apparatus includes a motion governor
operable to move said
cleaning member between said first and second positions. The roll cleaning
apparatus includes a
biasing member operable to urge the cleaning member against the roll. In
another feature, the
biasing member is mounted between the support member and a fitting that is
rigidly positioned
relative to the axis of rotation of the roll, and is operable to move the
support member, and the
cleaning member attached thereto, relative to the roll. In yet another
feature, a drive is mounted
to reciprocate the cleaning member axially relative to the roll. In a further
feature, the biasing
member employs a working fluid to urge the support to move. In another
feature, the drive is an
oscillator.
In another aspect of the invention, there is a paper making machine having a
first roll and
a second roll mounted in parallel and defining a nip therebetween. The first
roll is a heated roll,
having a temperature of greater than 160 F. The first roll has an axis of
rotation. A web
workpiece is mounted to run through the nip, the web workpiece having a non-
trivial clay
content. There is a roll cleaning apparatus for engagement with the first
roll. The apparatus
includes a cleaning member operable to engage the roll while the roll is
revolving and a carrier.
The cleaning member is mounted to the carrier. The carrier is mounted to
present the cleaning
member to the first roll. The cleaning member is movable between a first
position in which the
cleaning member engages the first roll, and a second position in which the
cleaning member is
located clear of the first roll. The cleaning member has a contact region
having both axial and
circumferential extent. The contact region is flexible in the radial direction
relative to the axis of
rotation of the first roll. The paper making machine further includes a second
roll cleaning
apparatus.
In another feature of that aspect of the invention, the first and second roll
cleaning
apparatuses are mounted to engage the first roll on opposite sides of the nip.
In a further feature,
at least the first roll cleaning apparatus has a drive connected to cause
axial reciprocation of the
cleaning member while the first roll is revolving. In another feature the
first roll cleaning
apparatus includes an actuator operatively connected to urge the cleaning
member against the
first roll.
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Brief Description of the Drawings
These and other features and aspects of the invention may become more apparent
upon a
reading of the following detailed description of examples embodying those
features and aspects
in which reference is made to the appended drawings of which:
Figure la is a general arrangement view in elevation of a roll assembly of a
paper making
machine;
Figure lb is an end view of the roll assembly of Figure la;
Figure 1c is a general arrangement, perspective view of the roll assembly of
Figure 1 a,
taken from one end of the roll assembly in a paper making machine of Figure
la;
Figure ld is an enlarged perspective view of a detail of the far, or distal,
end of the roll
assembly shown in Figure lc;
Figure le is an enlarged perspective view of a detail of the near end of the
roll assembly
of Figure lc;
Figure 2a is an end view of a portion of the roll assembly of Figure la
showing the
relative location of a roll cleaning apparatus;
Figure 2b shows an elevation view of the roll assembly of Figure 2a;
Figure 2c is an enlarged detail of Figure 2a;
Figure 3a is an end view of the cleaning apparatus of Figure 2a;
Figure 3b is an elevation view of the cleaning apparatus of Figure 3a;
Figure 3c is a partially sectioned enlarged detail of the cleaning apparatus
shown in
elevation in Figure 3a;
Figure 4a shows an end view of an alternate cleaning apparatus to that of
Figure 3a;
Figure 4b is a elevation of the apparatus of Figure 4a taken on arrow `4b';
Figure 4c is a plan view of the apparatus of Figure 4a, taken on arrow `4c';
Figure 5a shows an end view of an alternate apparatus to that of Figure 5a;
Figure 5b shows an enlarged detail of a cleaning head assembly of the
apparatus of
Figure 5a;
Figure 5c shows a side view of an alternate cleaning head assembly to that of
Figure 5a;
and
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Figure 5d shows a front view of part of the cleaning head assembly of Figure
5c.
Detailed Description
The description that follows, and the embodiments described therein, are
provided by
way of illustration of an example, or examples, of particular embodiments of
the principles of
aspects of the present invention. These examples are provided for the purposes
of explanation,
and not of limitation, of those principles and of the invention. In the
description, like parts are
marked throughout the specification and the drawings with the same respective
reference
numerals. The drawings are not necessarily to scale and in some instances,
proportions may
have been exaggerated in order more clearly to depict certain features of the
invention.
In the description that follows, reference may be made to papermaking
machines, to
calendar stack, and to rolls for calendar stacks of paper making machinery.
The construction and
operation of such machines may a involve rolls, and fittings for operation in
co-operation with
rolls. In that regard, a frame of reference may be defined in terms of a polar
cylindrical co-
ordinate system. Roll may have the general form of a body of revolution of
constant radius
formed about a central axis. This body of revolution may be considered as
having a long axis, or
axial direction, which may be termed the z-axis, that is concentric with the
roll; a radial direction
or radial axis, r, extending away from the z axis; and a circumferential
direction mutually
perpendicular to the axial and radial directions, referenced from an angular
datum. Similarly,
other fittings for co-operation with the roll, or rolls, may pivot about axes
parallel to the long
axis, and may move in translation parallel to the long axis.
Referring to the drawings, a papermaking machine may include a calendar stack,
such as
may be indicated generally as 10. Calendar stack 10 may have a pair of rolls
12, 14 defining a
nip 16. A web passes through the nip 16 as part of the papermaking process.
Papermaking
machine 10 has support frames 18 that support the ends of rolls 12 and 14.
Support frames 18
may be mounted to a foundation, and that may be taken as providing a fixed
datum for the
location of other fittings. Roll 12 may be provided with a heating apparatus,
such that the
surface of roll 12 may be maintained at a temperature that is above the
temperature of the
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surrounding room generally. Roll 12 may be heated to relatively high
temperatures such as may
be in the range of about 150 - 300 F, or more narrowly, 230 to 300 F. In some
instances roll 12
may be heated with steam or oil for extended periods of operation at greater
than 250 F. Roll 12
may be employed with a web workpiece, 20, that may be a paper web, during a
stage of
manufacture of that web workpiece. Web workpiece 20 may be a paper web, and
may be a
paper web having a non-trivial chemical content, whether of clay, starch or
some other chemical.
It may have a moderate or high starch or clay content, such as may be employed
in making
highly glossy surface finishes in coated paper or may be a calendared, or
super-calendared paper.
Calendar stack 10 may also have one or more web breakage sensors 15 mounted to
it, the web
sensor typically being an electric eye having a transmitter and a receiver or
reflected cantilevered
out to bracket the web path. When the optical signal is made, the automatic
control system for
the calendar stack, and for the paper making machine more generally, may infer
that there is no
web in place. The absence of a web may be due to a breakage of the web, and
the machine may
be caused to stop, usually relatively quickly. In normal operation, the feed
rate of the paper
making machine may be of the order of 2000 - 3500 feet per minute (fpm) at
calendar stack 10.
A roll cleaning apparatus, or assembly, is indicated generally as 22. Assembly
22 may
tend to extend longitudinally, generally parallel to the long axis of rolls
12, 14. To this end,
assembly 22 may be mounted to support frames 18, or to a base that is fixed in
position relative
to frames 18, and hence relative to the centerline axis of roll 12 of
papermaking machine
calendar stack 10, such that the radial position of assembly 22 may be known.
Assembly 22 may
span the full width of papermaking machine calendar stack 10.
Assembly 22 may be a mechanical contact cleaning apparatus, and may be a roll
scrubber. Assembly 22 may include stationary base members, such as may be in
the nature of a
pair of first and second, or left and right hand mounting fittings identified
as brackets 24, 26,
whose position is rigidly fixed with respect to support frames 18 (to which
they may be
mounted, as for example by bolted fittings. A support member in the nature of
a longitudinally
extending carrier 28 may be mounted to extend between brackets 24, 26.
Brackets 24, 26 are
similar to each other in design. Each may include a stationary member, such as
may be
identified as a base plate 30.
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A movable member, such as may be a plate 32, may be movably secured to the
stationary
member, namely plate 30, to permit objects mounted thereto to have a
displacement that includes
a component of motion in the radial direction relative to the long axis of
roll 12. In one
embodiment, this securement may be in the nature of a pin 34, such that when
installed the
relationship is that of a hinge or pivot whose axis is parallel to the long
axis of roll 12, so that
plate 32 has an angular degree of freedom relative to plate 30. An actuator,
or biasing member,
may be mounted to urge or cause motion between the movable member and the
stationary
member. By way of example, the actuator may be an hydraulic or pneumatic
actuator, such as
may be exemplified by a pneumatic bellows 36 located between the stationary
and movable
plates 30, 32 and may be operable to govern pivotal movement about the pin 34.
A second, or opposing actuator, or biasing member, or counterbalancing member
35, may
be mounted, such as to plate 30 or an extending arm 31 thereof, in opposition
to the first
actuator, exemplified by bellows 36. Counterbalancing member 35 may also be a
pneumatic
cylinder. The pressure in bellows 36, when activated, may be maintained at a
certain differential
over the pressure in counterbalancing member 35, such that the net resultant
force acting to
rotate carrier 28 may tend to be relatively small. For example, where the
pressure in bellows 36
may be 50 to 60 psia, the pressure in the cylinder of counterbalancing member
35 may be 40 or
50 psia, giving a constant pressure differential of 10 psi. (+/-). Assembly 22
may be in relatively
close balance relative to pin 34, with the static condition being such that
the weight of assembly
22 is distributed to cause assembly 22 to move away from roll 12 in the
default, or shut down,
condition when no pressure is available in bellows 36 or counterbalance
cylinder 35. When
bellows 36 is activated, the resultant imbalance may be sufficient to urge the
scrubbing member
(described more fully below) against roll 12. This may occur when the calendar
stack automatic
control senses a web speed greater than a suitable threshold value, be it 600
fpm, 1000 fpm, or
some other value which may be in a range such as 500 - 1500 fpm, that may be
below the
customary full operating speed of calendar stack 10 more generally. The
engagement pressure
on the footprint of assembly 22 against roll 12 may be comparatively soft. It
may be less than
0.1 psi, or, alternatively, may be less than 1"water gauge. As bellows 36 is
activated, the torque
applied may tend to move assembly 22 in a forward, or engagement, direction
into engagement
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with roll 12 relatively slowly. By contrast, should a paper breakage be sensed
by one of sensors
15, the automatic electronic control may cause pressure to be dumped from
bellows 36 very
quickly, resulting in a strong force (and consequently moment, or torque)
imbalance tending to
move assembly 22 in a rearward, or disengagement direction to a position away
from roll 12
more quickly, if not much more quickly (i.e., in the counter-clockwise
direction relative to pin 32
as viewed in Figures 2c, 3a and 4a, for example).
Apparatus 22 may include a motion limiting, or range of motion defining
member, such
as an abutment or stop 38. Stop 38 may be adjusted to inhibit movement of the
movable
member, namely plate 32 beyond a predetermined motion end position in the
forward or
engagement direction (clockwise in Figures 2e, 3a and 4a). Apparatus 22 may
also include a
standoff, or rest, 39, that limits motion in the direction (counter-clockwise
in Figures 2c, 3a and
4a) away from roll 12 that may provide a support upon which to rest plate 32
(and the attached
parts of assembly 22) when bellows 36 is not energized. Contact of plate 32
against stop 38 may
generate a signal to the automatic control of assembly 22, or of calendar
stack 10 more generally,
as may be, to cause a maintenance annunciator signal to be provided to the
operator. It may also
cause assembly 22 to be moved away from roll 12. That is, the contact of plate
32 against stop
38 may be inferred as being due either to the absence of a roll interface
engagement member of
assembly 22, or it may be due to a need to replace a worn out roll interface
engagement member.
In either case, it may be appropriate to notify an attendant.
Carrier 28 may include a beam member 40. Beam member 40 may be of hollow
section.
In one embodiment, the beam of hollow section may have the form of a
cylindrical shaft 42,
which may be of circular section. Beam member 40 may have mounting fittings
that permit
motion between beam member 40 and movable plates 32. In particular, those
fittings may
permit a degree of freedom in linear translation, such as linear axial motion
of beam member 40
relative to roll 12. To that end, beam member 40 may have longitudinally
slidable guides, or
ways, mounted at either end thereof. Those ways may be in the form of circular
cylindrical stub
shafts 44, or journals, machined and mounted at either end of the hollow
shafting, to define
trunnions. Those trunnions may be carried in bearings 50 and mounted in
trunnion blocks 46,
that are rigidly mounted to plates 32. Where stub shafts 44 are circular, beam
member 40 may
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also tend to have an angular degree of freedom, namely the ability to move
angularly about its
own longitudinal axis. Rotation of the shaft 42, and hence the rotational
degree of freedom, may
be inhibited by a key 48 acting between the shaft 42 and trunnion block 46.
The stub shafts 42
are supported in slide bearings 50 that support the tubular housing defined by
the hollow section
of beam member 40. Shafts 42 can slide axially relative to blocks 46 and
bearings 50.
Block 46 may have an upper portion 45 and a lower portion 47. Those portions
may be
held in place by mounting fittings, which may be in the nature of bolts. The
bolts may be
secured by quick release fasteners, such as nuts or wingnuts. Block 46 may
have a first keyway
position 41, which, in the example, may be at about the 12 o'clock or top
position, and a second
keyway position, 43, which may be located at some other angular location, be
it, for example,
about 90 degrees away such as the 3 o'clock position in Figure lc. (or,
looking from the other
direction, 9 o'clock in Figure 5a). When maintenance of assembly 22 is
required, such as, for
example, to change a roll engagement interface member, which may be a pad such
as pad 92,
discussed below, the operator may find, or place, carrier 28 in the "away"
position. The upper
portion 45 of block 46 may be removed by releasing the quick release fasteners
49. This permits
the operator to rotate assembly 22 on shafts 42 of carrier 28 from a first
position, corresponding
to the 12 o'clock position of key 48, for example, to a second position, which
may correspond to
the 3 o'clock position of key 48. Assembly 22 may include a handle 51, such as
may be attached
to carrier 28, to facilitate this movement. The second position may be termed
an inoperative, or
maintenance position. In the 3 o'clock position, the interface engagement
assembly (such as
item 60, discussed below) may present the pad in an upwardly facing,
relatively convenient
orientation, such that the operator may pull off the old pad, and install a
new pad. Once the new
pad has been installed, the assembly may be returned to the 12 o'clock
position, the upper
portion 45 of block 46 replaced and re-secured in position, and operation of
apparatus 22 may re-
commence.
As shown in the embodiments of Figures 4a and 5a, a longitudinal motion drive,
such as
may tend to urge, cause and govern longitudinal displacement of carrier 28
relative to bearings
50, and hence to the axis of roll 12, may be indicated generally as 52.
Longitudinal motion drive
52 may be a reciprocating drive, and may be identified as an oscillator 54.
Drive 52 is rigidly
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mounted to movable plate 30 and acts on a bracket mounted to beam member 40,
to cause it to
reciprocate along the shaft in a uniform periodic motion. Oscillator 54 may be
air driven.
Carrier 28 may support an array of brackets 56. The members of this array of
brackets
may be spaced on relatively even pitches along the length of the carrier 28.
Brackets 56
extended toward roll 12 and support at their distal end a cleaning member such
as may be
identified as cleaning head assembly 60. Brackets 56 may each include a hinge
fitting 58, those
hinge fittings being aligned along a common axis of rotation parallel to the
axis of rotation of
roll 12.
Cleaning head assembly 60 may include a backing member 64, backing member
support
fittings 66, and a work surface contacting member, or assembly 68. The backing
member 64
may have the form or a longitudinally extending beam, such as a channel member
70. Channel
member 70 may have a web portion 72 and flanges 74, 76 oriented to extend from
either side of
web portion 72 and substantially radially away from ro1112. It may be that web
portion 72 has a
surface 78 facing predominantly toward roll 12. Web portion 72 may be formed
on an arcuate
contour such as may tend to yield a concavity having a radius of curvature
generally conforming
to the curvature of roll 12. Mounting members, or support fittings 66 may
include brackets 80
and, may be mounted to the radially outwardly facing side of channel member 70
at spacings
corresponding to the pitch spacing of brackets 56. At the outermost extremity
or stem 82 of each
bracket 80 there may be a pivot fitting 84 for co-operation with a pin 86 and
the corresponding
hinge fitting 58 (and which may include suitable bushings or other standard
hardware). It may
be that the distal end of stem 82 has abutments 88 that may interact with
shoulders 90 of hinge
fittings 58 to limit angular motion of channel member 70 relative to carrier
28 about the axis of
the hinge fittings 58.
Backing member 64 may be termed a shoe, mounted for co-operation with rol112.
A pad
92 such as may be used for engagement of the surface of the roll 12 may be
secured to overlie
surface 78, and thus to form a lining of the shoe defined by backing member
64. Pad 92 may
have a thickness, t, and a relative softness, that may tend to provide a
cushion against the outside
of roll 12. When biased against roll 12 by the action of a biasing member,
such as pneumatic
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bellows 36, pad 92 may tend to provide a contact interface continuously along
the length of the
outer circumferential surface of roll 12. The rotation of roll 12 may then
tend to bring every part
of its outer surface into contact with pad 92 at some point during operation.
Thickness t may be
in the range of %2 to 1 inches. Pad 92 may subtend a modest portion of the
circumference of roll
12. That portion may be in the range of 5 - 45 degrees of arc, and may, in one
embodiment,
subtend about 15 - 35 degrees of arc. Alternatively, the width of pad 92,
measured as a chord of
the subtended arc, may be in the range of about 2 to about 12 inches, an in
one embodiment may
be about 4 - 8 inches, and may be about 6 inches. Pad 92 may tend to be
flexible, or
compressible, in the radial direction, and may tend to have a two-dimensional
contact area (that
is, contact defined be a patch having both an axial and a circumferential
extent) over a significant
area, as opposed to a rigid, (i.e., by comparison, substantially unyielding)
doctor blade such as
may tend to have unidimensional engagement (i.e., line contact). The limit of
motion under this
biasing may be established by the setting of stop 38.
In one embodiment, pad 92 may be formed from an abrasive scouring material
such as a
nylon mesh, having an abrasive high strength aluminium oxide or silicon
carbide impregnation.
Alternatively, it may be a cloth having a fine abrasive surface. Two
commercially available
products are Scotch Brite (t.m.) manufactured by 3M, and Beartex (t.m.)
manufactured by
Norton. Other similar products may also be used. Pad 92 may be secured to the
surface of the
shoe, that is, backing member 64, by securement fittings, or fastenings. In
one embodiment,
those securements may be in the form of co-operating male and female hook and
loop fasteners,
indicated as 94, such as those sold under the trademark Velcro, mounted to the
front, or radially
inward, face of backing member 64. In one embodiment, the components of hook
and loop
fastener 94 are formed from a stainless steel and capable of operation at
elevated temperatures,
which is to say temperatures in excess of 180 F, over an extended period of
time.
In the alternative embodiment of Figures 5a and 5b, assembly 60 may be
replaced by
alternate assembly 100. Alternate assembly 100 may include a longitudinally
running backing
member 102 that is supported at spaced intervals by brackets 104 mounted on
corresponding
pitches, and for co-operation with, brackets 56 in the same, or substantially
the same, manner as
brackets 56. Assembly 100 may have a roll engagement interface member. In one
embodiment
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that roll engagement interface member may have the form of a two dimensional
array, or pad,
such as may be identified as scrubbing element 106. Scrubbing element 106 may
have a
roughness the same, or comparable to, that of the other embodiments herein
described, and may
employ Scotch Brite or Beartex or such other materials as noted above.
Scrubbing element 106
may be in the form of an abrasive grid or mesh of metal, or metal treated
nylon, and may be such
as to permit removal and washing, or removal and reconditioning, or removal
and replacement as
may be appropriate. Scubbing member 106 may include a sheet or abrasive cloth.
In operation,
the biasing of bellows 36 may tend to maintain scrubbing member 106 in contact
with roll 12
over a circumferential arc and under a substantially two dimensional
(longitudinal and
circumferential) pressure field in which the pressure field acts substantially
radially inward with
respect to roll 12, as the manner noted above.
The longitudinal pad carrier, or scrubbing element carrier, namely backing
member 102,
may be in the form of a hollow section member, as indicated by the somewhat D-
shaped section
illustrated in Figure 5b. This section may have a longitudinally running web
or back 108 for
releasable connection to brackets 104, and legs 110, 112 extending from back
108 toward roll 12
(as deployed in use). Member 102 may also have a front, or roll engagement
side or face, or
portion 114 extending between legs 110, 112. Portion 114 may have a form, or
concavity,
generally conforming to the outside radius of roll 12. Portion 114 may include
relief or indexing
features 116 such as may engage or retain scrubbing element 106. Portion 114
may have a
flexing capacity to conform to ro1112. Backing member 102 may be formed as an
extrusion, and
may be formed of Aluminum. T-shaped slots 120 may be formed in back 108, such
as to admit
corresponding securement fittings 122 by which member 102 may be connected to
brackets 104.
In the further alternate embodiment of Figures 5c and 5d, which may be in
other respects
the same as, or similar to any of the other embodiments described herein, a
backing member 130
(otherwise similar to backing member 102), may be a plenum. That is, member
130 may have a
roll engagement wall 132 having an array of lengthwise running grooves 134.
Array 134 may
include a first pair of grooves 135, 136 toward one edge, a second pair of
groves 137, 138
generally centrally located along the arcuate face, and a third pair of
grooves 139, 140 located
near the other edge of the arcuate engagement face. Hook and loop attachment
strips 142,144
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(such as Velcro), may be mounted between the first and second, and second and
third pairs of
grooves and may be used to provide a releasable securement of the roll
engagement member,
that member being a pad 146, generally similar to pad 92.
The grooves of array 134 may be provided with a pattern of apertures, or
vents, or slots,
inlets, or openings 150, such as to permit air to be drawn from the region of
pad 146 into the
internal plenum of backing member 130 indicated generally as 148. For example,
backing
member 130 may be capped at one end, and a vacuum line attached to the other
end.
Alternatively, a plenum outlet fitting, which may be in the nature of a header
fitting 152, may be
attached to both ends of backing member 130 to permit air extraction at both
ends, which may
occur in a generally symmetrical manner. A suction hose 154 may be connected
between header
fitting 152 and a vacuum pump, or blower or extracter indicated as 156. A
filtering, or settling
apparatus 158 may also be employed.
In this way, backing member 130 may define an exhaust manifold through which
air may
be extracted through pad 146. This air may tend to carry away dust and lint
particles, and may
provide ventilation to pad 146 more generally.
Openings 150 may be unequally distributed. That is to say, in a region 160 far
from the
header fitting 152, which region may be a region near the center of backing
member 130, the
number of openings may be relatively large, or the size of the openings may be
relatively large,
such as to permit a generally low resistance to air flow. In an intermediate
region 162, the size
or number, or both, of openings 150 may be somewhat smaller, and may present
somewhat
greater impedance to airflow. In an end region 164 close (i.e., proximate) to
header fitting 152
openings 150 may be somewhat smaller and fewer again, and may be more widely
spaced. The
transition from a high density of openings to a low density of openings may be
continuous, or
may involve discrete changes of regime. Openings 150 may be staggered from row
to row, such
that a slot in groove 135 may be offset from a slot in groove 136, and so on.
The slots in groove
135 may be partially occluded and partially exposed relative to the edge of
pad 146. The slots in
groove 140 may be partially occluded and partially exposed by the other edge
of pad 146. The
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size, aspect ratio (length v. width), number, and spacing of openings 150 may
vary according to
the operating parameters of the assembly.
In operation, the roll cleaning apparatus, or scrubbing device may initially
be in a rest
position away from the surface of the ro1112. That is to say, in that `away'
position, pad 92 may
rest clear of roll 12, and there may be a clearance gap `G' therebetween. In
this `away' position
pad 92 may be installed, or replaced from time to time, as may be required
should the working
surface of pad 92 become worn or clogged. Pad 92 may also be moved to the
`away' position in
the event that the paper web running through nip 16 should break.
Once a web of material, such as a web of paper, has been fed through nip 16
successfully,
and the calendar rolls are turning at speed, pad 92 may be moved from the
first, away, position to
a second, engagement position, in which pad 92 bears against the outer
circumferential surface
of rol112. This motion from the first position to the second position may be
driven by a biasing
member, or drive member, such as through the application of greater pressure
to bellows 36.
This may tend to cause displacement of plate 32, as by pivoting movement about
pin 34, with a
radial component of displacement (relative to roll 12) being imparted through
carrier 28 and
backing member 64 to pad 92, causing it to move radially closer, and thereby
into contact, with
roll 12. This may tend to cause pad 92 to be brought into engagement with the
surface of rol112
and, under that biasing or urging, for pad 92 to conform to the surface of the
roll 12. Pad 92 may
pivot about the pivot pin 86 to find an equilibrium position. That is to say,
the rotational degree
of freedom afforded by the hinge fitting at pin 86 may tend to permit pad 92
to be self centering.
In the event that the workpiece web, such as a web of paper, should tear or
break during
operation, pad 92 can be retracted relatively quickly, as iioted above.
Upon engagement with roll 12, the abrasive surface of pad 92 may tend to clean
the
surface of roll 12. During this engagement, carrier 28, and hence pad 92, may
be caused to move
axially (that is in the longitudinal direction parallel to the axis of
rotation of roll 12) under the
urging of a longitudinally operable drive 52 , such as oscillator 54. It may
be that the drive
member may be used to yield a linearly reciprocating motion, and that linearly
reciprocating
motion may be a periodic oscillation. For example, in one embodiment, as
oscillator 54 acts on
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the beam member 40, the shaft 42 is displaced axially within the trunnion 46
but supported by
the bearing block 50. The key 48 in the shaft 42 inhibits rotation of the
shaft relative to the
mounting plates and thus permits the transmission of a moment to hinge
fittings 58. This
moment may tend to yield a force at the pivot pin, that force having a
component tending to
compress pad 92, and tending to maintain the shoe in contact with the roll.
This may tend to
result in a sinusoidal path being traced out on the surface of roll 12 as roll
12 revolves.
It may be that the rate of linear oscillation of beam member 40 may be a
function of the
rate of revolution of roll 12. It may be that the period of oscillation is
chosen to be a non-
harmonic of the angular velocity of roll 12. For example, the rate of
oscillation may be a non-
integer fraction of the angular velocity, and may be in the range of 1- 10
cycles per minutes. In
one embodiment it may be about 3 cycles per minute. The amplitude of
oscillation may be
proportional to either the arc subtended by pad 92 or to the radius of rol112.
For example, the
amplitude of oscillation may be in the range of 1/20 to %2 of the arc length
subtended by pad 92.
Alternatively, the oscillation may be in the range of 1/10 to 1/3 or the
radius of roll 12. In one
embodiment, the amplitude may be about 1 inch from a central, at rest
position, giving a total
range of axial motion of about 2 inches from one extreme to the other.
It may be that the relatively large contact area between the abrasive surface
of pad 92 and
the roll 12 may provide cleaning of the entire roll surface (or of such width
or roll 12 as may
engage the web workpiece). The oscillation of pad 92 in the axial direction
may tend to deter
streaking on the surface of the roll.
Various embodiments of the invention have been described in detail. Since
changes in
and or additions to the above-described best mode may be made without
departing from the
nature, spirit or scope of the invention, the invention is not to be limited
to those details but only
by the appended claims.
