Note: Descriptions are shown in the official language in which they were submitted.
- 1 -
Title: SELF-ALIGNING SUPPORT SYSTEM FOR A ROTATING BODY
Technical Field
[0001] The embodiments disclosed herein relate to supporting rotating
bodies,
and, in particular to a self-aligning support system for a rotating body.
Introduction
[0002] This disclosure relates to a roller support mechanism and method
for
supporting a rotating body, particularly a large rotating body such as a hot,
rotary kiln.
[0003] Large rotating cylinders are used in carrying out a large number
of
economically important processes. Such rotary, trunnion supported equipment
typically
includes a steel tube that may be quite long (up to several hundred feet in
length), and
that is supported by annular tires spaced along the length of the tube. These
tires can
be up to 25 feet in diameter or larger. Each tire is carried on a pair of
opposed rollers,
which in turn may be mounted upon a concrete pier or pad. The steel tube is
rotated
about its longitudinal axis, and is supported for such rotation by contact of
the rollers
with the tires surrounding the tube. The rollers are supported upon the piers
or pads by
roller support bearings. These are typically sleeve bearings on the larger
equipment and
antifriction bearings on smaller sized equipment.
[0004] Due to the wear and tear of the roller support bearings, the
rollers, and the
tires, and distortion of various parts of the system (including possible
movement of the
piers or pads upon which such rotary equipment is mounted), the rollers can
get out of
alignment so as to cause the equipment to rotate with greatly increased
stresses and
friction. Since the cost of replacing the bearings or rollers, or both, is
relatively high, an
important consideration in the operation of such rotary equipment is the
maintenance of
proper alignment between the surface of a roller and the supporting tire to
prevent
uneven wearing of the respective surfaces and overloading the bearings. If the
two are
kept in proper alignment, a long life can be expected from the tire and the
rollers and
the bearings.
[0005] Alignment relationships are complicated by the fact that such
rotary
equipment is typically constructed with the tube on a slight slope relative to
horizontal to
CA 2972364 2017-07-05
- 2 -
facilitate the flow of material therethrough. Thus, the tube exerts an axial
force due to
gravity (as well as other axial loads that may be place upon it in operation),
thereby
causing an axial thrust load to exist on the rollers and their associated
roller support
bearings whenever they are required to counteract gravity to keep the tube
running on
the rollers. In order to maintain proper alignment between the tube and roller
support
bearings, it has previously been necessary to periodically check the alignment
by visual
inspection or by sophisticated alignment measurements, to determine roller
axial
position as best possible.
[0006] Since such measurements can never be accurate enough, incremental
roller adjustments for skew are made until the roller shifts axially into a
desired position
that is approximately parallel with the axis of the tube. Sleeve bearing
arrangements are
configured to allow an axial shift of the roller and shaft assembly of
approximately 6 mm
for this purpose. In this way, the skew adjustment causes this axial shift
whenever the
neutral skew position is crossed. However, this method is inadequate whenever
antifriction bearings are employed, because they are required to be locked to
the roller
shaft either by shrinking or other mechanical means. No allowance for physical
axial
shift between the bearing and shaft exists. Since the amount of skew
adjustment to
cause a roller to shift axially is on the order of 0.1 mm (0.004 inches) or
even less, no
matter what size of roller, even as large as 10 feet in diameter, it is all
but impossible to
measure skew since the axis of rotation of the tube can never by physically
established
to that fineness. Since antifriction bearings by their very design do not
allow any such
axial shift, the checks must be made relatively often, are difficult to
evaluate, very
subjective, and in most instances are not dependably carried out by the
operator.
Summary
[0007] A method and apparatus for support roller self-alignment which
rotatably
supports a rotating body. The apparatus is a pivot plate onto which each
support roller,
fitted with two bearings, is mounted. The pivot plate is mounted between the
roller's
support bearings and the structural support frame normally found with such
assemblies.
The pivot plate is pinned in such fashion that the axial thrust force
generated by a
misaligned or skewed roller drives the roller support assembly towards the
aligned or
CA 2972364 2017-07-05
- 3 -
neutral skewed position. As the assembly approaches the neutral skew, aligned
position the axial thrust force is proportionately reduced and diminishes to
zero when
the aligned position is attained.
[0008] According to some embodiments, there is an apparatus for rotatably
supporting a rotating cylindrical body, the apparatus comprising: a pair of
roller
assemblies for supporting an annular bearing surface of a rotating cylindrical
body, each
of the roller assemblies comprising: a cylindrical roller having a
circumferential bearing
surface in supporting engagement with the annular bearing surface of the
rotating body;
first and second shaft extensions extending from the roller; bearings for
rotatably
supporting the first and second shaft extensions; and a pivot plate for
supporting the
bearings, the pivot plate being pivotally attached to a base by a pivot pin
such that the
cylindrical roller self-adjusts to the annular bearing surface of the rotating
body.
[0009] The pivot pin may be located in line with the center of where the
circumferential bearing surface is in contact with the annular bearing
surface. The pivot
plate may be mounted such that if the rotation axis of the roller is not
parallel to the
rotation axis of the rotating body, the roller produces an axial thrust force
on the rotating
body, and the pivot plate pivots to drive the roller in the opposite direction
as a
reactionary force to the axial thrust force.
[0010] The pivot plate may pivot due to the reactionary force and is
driven
towards an aligned position, which when reached, reduces the reactionary force
to zero.
[0011] The base may include a base extension for supporting the pivot
pin, and
wherein the base is anchored to a foundation.
[0012] The rotating body may be horizontal and the apparatus includes a
pair of
thrust rollers exhibiting gaps between the thrust rollers and the bearing
surface.
[0013] The pivot plate may have an underside with reduced friction.
[0014] The pivot plate may have two layers, a first layer for supporting
the
bearings and a second layer having low friction and high heat resistance.
CA 2972364 2017-07-05
- 4 -
[0015] The rotating body may be installed on an incline relative to the
horizontal
and wherein the apparatus includes a downhill thrust roller in full contact
and running
continuously on the bearing surface.
[0016] The rotating body may be installed on an incline relative to the
horizontal
and wherein each roller assembly has an axial adjustor to fix the pivot plate
for each
roller assembly such that the combined thrust generated by all the roller
assemblies
equals the gravitational pull on the rotating body. The axial adjustor may
lock the pivot
plate with an axial fixing screw to establish axial balance of the rotating
body.
[0017] The bearings may be spherical roller bearings. The bearings may be
sleeve bearings and button style thrust bearings.
[0018] The support assembly may allow free axial travel of the shaft
extensions in
the sleeve bearings when the rotating body is a 100% thrust kiln.
[0019] Where a lack of uniformity of contact between the bearing surface
of the
rotating body and the circumferential bearing surface creates a gap between
the roller
and the bearing surface, the apparatus may further comprise a corrective shim
placed
under the bearings sized to angle the roller assembly based on the size of the
gap.
[0020] The pivot pin may have a pivot axis that is generally
perpendicular to the
axis of rotation of the rotating body.
[0021] The rotating body may have a tire having the bearing surface,
wherein the
tire is mounted on the rotating body having bends causing the tire to wobble,
and
wherein the roller assemblies pivot on the pivot plate to allow the position
of a roller axis
to dynamically respond and move with a tire rotation axis, seeking to maintain
a zero
thrust load.
[0022] The rotating body may include any one of a rotary kiln, a rotary
cooler, a
rotary dryer, a rotary furnace, a rotating reactor, a rotary filter, a bean
conditioner, a
corn conditioner, a rotary ash cylinder, a trunnion supported rotary mill, a
de-lacquering
drum, a washer, a debarking drum, a pelletizer, a coal breaker, a granulator,
an
incinerator, or a shakeout drum.
CA 2972364 2017-07-05
- 5 -
[0023] According to some embodiments, there is a roller assembly for
supporting
an annular bearing surface of a rotating cylindrical body, the roller assembly
comprising:
a cylindrical roller having a circumferential bearing surface in supporting
engagement
with the annular bearing surface of the rotating cylindrical body; first and
second shaft
extensions extending from the roller; bearings for rotatably supporting the
first and
second roller shaft extensions; and a pivot plate for supporting the bearings,
the pivot
plate being pivotally attached to a base by a pivot pin such that the
cylindrical roller self-
adjusts to the annular bearing surface of the rotating body.
[0024] The pivot pin may be located in line with the center of where the
circumferential bearing surface is in contact with the annular bearing
surface.
[0025] Other aspects and features will become apparent, to those
ordinarily
skilled in the art, upon review of the following description of some exemplary
embodiments.
Brief Description of the Drawings
[0026] The drawings included herewith are for illustrating various
examples of
articles, methods, and apparatuses of the present specification. In the
drawings:
[0027] Figure 1 is a side elevation view of a rotary kiln, according to
one
embodiment;
[0028] Figures 2A and 2B are a perspective views of conventional support
assemblies;
[0029] Figure 3 is a perspective view of a pair of roller assemblies
shown in
Figure 1;
[0030] Figure 4 is a perspective view of the roller assembly of Figure 3
in use,
[0031] Figures 5A, 5B, and 5C are top, side, and end views, respectively,
of the
rotary kiln of Figure 1;
[0032] Figure 6 is a top view of the pair of roller assemblies of Figure
3 in a left
orientation, a centered orientation, and a right orientation, respectively;
CA 2972364 2017-07-05
- 6 -
[0033] Figures 7A and 7B are close up views of a roller assembly having
thrust
rollers in accordance with an embodiment;
[0034] Figure 8 is a perspective view of a roller assembly having lower
thrust
rollers in accordance with an embodiment;
[0035] Figure 9 is a top view of a rotating body showing tire wobble;
[0036] Figure 10 is a perspective view of a roller assembly having an
axial
adjustor, in accordance with an embodiment;
[0037] Figures 11A and 11B are side views of a roller assembly having
sleeve
bearings, in accordance with an embodiment; and
[0038] Figures 12A and 12B are perspective views of a roller assembly
having a
shim, in accordance with an embodiment.
Detailed Description
[0039] Various apparatuses or processes will be described below to
provide an
example of each claimed embodiment. No embodiment described below limits any
claimed embodiment and any claimed embodiment may cover processes or
apparatuses that differ from those described below. The claimed embodiments
are not
limited to apparatuses or processes having all of the features of any one
apparatus or
process described below or to features common to multiple or all of the
apparatuses
described below. It is possible that an apparatus or process described below
is not
covered by any of the claimed embodiments. Any embodiment disclosed below that
is
not claimed in this document may be the subject matter of another protective
instrument, for example, a continuing patent application, and the applicants,
inventors or
owners do not intend to abandon, disclaim or dedicate to the public any such
embodiment by its disclosure in this document.
[0040] Although the discussion herein and illustrations mostly depict a
rotary kiln,
the present disclosure is applicable to any rotating body supported on
trunnion rollers.
Such rotating bodies include, for example, rotary kilns, rotary coolers,
rotary dryers,
rotary furnaces, rotating reactors, rotary filters, bean conditioners, corn
conditioners,
rotary ash cylinders, trunnion supported rotary mills, de-lacquering drums,
washers,
CA 2972364 2017-07-05
- 7 -
debarking drums, pelletizers, coal breakers, granulators, incinerators, and
shakeout
drums, among others.
[0041] Referring to Figure 1, illustrated therein is a rotary drum 100 on
an incline,
being generally of a high length to diameter ratio, is rotatably mounted upon
piers 102,
104, 106 and 108. Rotary drum 100 has a rotating cylindrical body 110 such as
a
rotatable tube or shell. Adjacent each pier, the rotating body 110 has a tire
112 which
defines an annular bearing surface 114 which is generally cylindrical and
coaxial to a
longitudinal rotation axis 116 of the rotating body 110. The bearing surface
114 of each
tire 112 is supported by a pair of roller assemblies 118 and 120. The roller
assemblies
118 and 120 are arranged in pairs along the length of the rotating body 110,
are aligned
and configured to support the rotating body 110, and are generally identical.
Depending
on the size of the rotary drum 100 each pair of roller assemblies 118 and 120
may carry
a load of over 1000 tons. The roller assemblies 118 and 120 may operate 24
hours a
day for most days every year.
[0042] Figures 2A and 2B illustrate a conventional support assemblies
200, 250
respectively having spherical roller bearings 202 (Figure 2A) or sleeve
bearings 252
(Figure 2B).
[0043] Figure 2A illustrates the conventional support assembly 200 having
a
roller 204, a base 206, the spherical roller bearings 202, and manual skew
adjustors
208. The conventional support assembly 200 is typically found on rotary
coolers, rotary
dryers, rotary furnaces, rotating reactors, rotary filters, bean conditioners,
corn
conditioners, rotary ash cylinders, trunnion supported rotary mills, de-
lacquering drums,
washers, debarking drums, pelletizers, coal breakers, granulators,
incinerators, and
shakeout drums, among others.
[0044] Conventionally, the spherical roller bearings 202 are fixed
directly to the
base 206, for example by hold down bolts 210. The spherical roller bearings
202 are
capable of skew adjustment by the manual skew adjustors 208, such as adjusting
screws. The adjusting screws allow for skew adjustment of the axis 212 of each
of the
rollers 204 with respect to the axis of the tire 214, as is known in form and
structure in
the art. Such skew adjustments are made while the equipment is rotating, with
the hold
CA 2972364 2017-07-05
- 8 -
down bolts 210 released enough to allow the spherical roller bearings 202 to
slide
(transverse to the axis of the roller) relative to the base 206. Some
spherical roller
bearings 202 are not mounted to the base 206 by hold down bolts 210, but are
still
prevented from axial movement relative to the base 206 using keys (not shown).
[0045] When the roller 204, crosses its neutral axis, no axial travel is
visible. This
complicates the alignment of roller 204. Without identifying the location of a
roller's
neutral axis, alignment cannot be established. In this case, the problem is
magnified
because equipment similar to kilns, which employ spherical roller bearings,
greatly
outnumber kiln installations, by a factor of at least 100:1. These are, for
example, rotary
coolers, rotary dryers, balling drums, granulators, incinerators, or rotary
washers. Most
of these turn much faster, often 3 to 4 times faster, which makes alignment
proportionately more critical.
[0046] Figure 2B illustrates the conventional support assembly 250 having
the
sleeve bearings 252 and button style thrust bearings 254 for a roller shaft
256
supporting a roller 258. Conventionally, the neutral skew position of the
sleeve bearings
252 is found not by measurement but by observing a shift of the roller 258
from one side
(left, right) to the other in response to a few thousandths bearing position
adjustment
260 of a skew adjustor 262. Observing the shift of the roller 258 happens when
the
bearing position adjustment 260 causes the roller 258 to cross its neutral
skew position.
When the roller 258 is skewed 260, a force is generated pushing the kiln 264
axially
266. As a response, the roller 258 pushes itself in the opposite direction
268. Each
time the roller 258 crosses the neutral position the thrust force changes 180
and the
roller 258 moves from one side to the other (left, right in Figure 2B).
[0047] While the rotating axis of the kiln 264 is practically difficult
to fix by
measurement, the roller position with respect to being parallel to that axis
may be
established (e.g., to the nearest 1 thousandths of an inch) by observing the
axial shift of
the roller 258 when the roller 258 moves across its neutral axis.
[0048] Referring now to an embodiment of the present disclosure, Figure 3
illustrates the roller assemblies 118 and 120 for supporting the bearing
surface 114 of
the rotating body 110. Each roller assembly 118 and 120 has a cylindrical
roller 122
CA 2972364 2017-07-05
- 9 -
and 124, and each roller 122, 124 has a circumferential bearing surface 126
and 128,
respectively, which is in supporting engagement with the bearing surface 114
of the tire
112.
[0049] Where the rotating body is inclined, each roller 122 and 124 has
an
upstream roller shaft extension (shaft extension 130 for roller 122, shaft
extension 132
for roller 124) and a downstream shaft extension (shaft extensions 134 and 136
for
rollers 122 and 124, respectively). As used herein, the "upstream" and
"downstream"
orientations are relative to the direction of material flow through the
rotating body (from
left to right in Figure 3).
[0050] The shaft extensions 130, 132, 134, 136 are rotatably supported by
bearings 138, 140, 142, 144, respectively. Bearings 138 and 142 are shown for
shaft
extensions 130 and 134 of roller 122 respectively. Bearings 140 and 144 are
shown for
the shaft extensions 132 and 136 of roller 124. Such bearings may be spherical
roller
bearings, as shown, sleeve bearings, or antifriction bearings, for example.
Each bearing
thus includes one of a pair of bearings for its respective roller. In the case
of antifriction
bearings, one bearing of the pair will contain a fixing ring and the other
bearing of the
pair will be a free bearing.
[0051] The bearings 138, 140, 142, 144 of each roller 122, 124 are
fixedly
mounted to a pivot plate 146, 148. The pivot plates 146, 148 are pivotally
attached to a
base 150 by a pivot pin 152, 154. The pivot plate 146, 148 allows the roller
assembly
118, 120 to pivot about the pivot pin 152, 154. The pivot pin 152, 154 may be
located on
one side of the roller assemblies 122, 124. The pivot pin 152, 154 is located
at the
center of the roller 122, 124. The pivot pin 152, 154 may be located in line
with the
center of where the circumferential bearing surface 126, 128 is in contact
with the
bearing surface 114. The location of the pivot pin 152, 154 is dictated by the
direction of
roller rotation. The pivot pin 152, 154 is in front of the upturning side of
the roller 122,
124. If the pivot pin 152, 154 were to be located in front of the down turning
face of the
roller 122, 124, the axial force generated by a misalignment would cause the
roller 122,
124 to misalign even more and be forced out from under the tire 112 to one
side or the
other causing the system to fail.
CA 2972364 2017-07-05
- 10 -
[0052] Where the drum 100 is alternately rotated in both directions
because of
the process being performed, the self-alignment is done first with the drum
100 rotating
such that the pivot pins 152, 154 are in front of the upturning face of the
roller 122, 124.
In this case, an axial adjustor (such as axial adjustor 188 and axial
adjusting screw 190
of Figure 10) must be employed on both sides of the pivot plate 146, 148 to
lock the
pivot plate 146, 148 in place, thereby enabling safe reverse rotation.
[0053] The pivot plate 146, 148 can be a simple mild steel plate or one
that has
the underside polished to reduce friction. In an embodiment, the pivot plate
146, 148
may also have two layers, a first layer 145A, 147A for supporting the bearings
and a
second layer 145B, 147B having low friction and high heat resistance such as
Teflon.
The load bearing or friction reducing configurations of the pivot plate 146,
148 may be
determined, case by case, dependent on the equipment size, weight and speed
etc.
[0054] The base 150 is typically formed from a steel frame made of heavy
H-
section steels channels which are welded together. As a retrofit, the base 150
includes
a base extension 156 for providing an aperture for the pivot pin 152, 154. The
base 150
and base extensions 156 are anchored to a foundation 160 which may take the
form of
a pier (such as piers 102, 104, 106 or 108) or a foundational pad. The
foundation 160 is
typically formed from concrete, and the base 150 is anchored to the foundation
160,
either by fasteners such as bolts (not shown) or by forming the base 150 into
the
concrete of the foundation 160 itself.
[0055] Figure 4 illustrates forces acting on the roller assembly 118
mounted on
the pivot plate 146. The rotating body 110 rotates in a direction of rotation
162. An
axial thrust load or force 164 on the rotating body 110 creates a consequent
axial force
reaction 166 on the roller assembly 118 created by an indicated skew 167.
[0056] If the roller 122 is not parallel to the rotating body 110, the
roller 122
produces the axial thrust force 164 on the rotating body 110. As a reaction to
the axial
thrust force 164, the roller 122 drives itself in the opposite direction 166.
The reaction is
facilitated by the pivot plate 146, on which the roller assembly 118 is
mounted and
which is free to move about pivot axis 170 in response to the axial thrust
force 166. The
pivot plate 146 will therefore reposition itself due to the reactionary force
166 and drive
CA 2972364 2017-07-05
-11 -
itself towards the aligned position, which when reached, reduces the
reactionary force
166 to zero. The roller assembly 118 is therefore self-adjusting as it
continues to seek a
neutral skew or aligned position as long as the rotating body 110 rotates and
the pivot
plate 146 is free to move. This self-adjusting reduces the roller support
bearing thrust
loading 164 to the minimum thereby minimizing friction and wear. This self-
adjusting
may also consequently eliminate the need to measure skew alignment or manually
reposition rollers for that purpose (as described with reference to Figures 2A
and 2B).
[0057] For good, reliable operation, the roller axis 172 of each roller
122 is
parallel to the rotation axis 116 of the rotating body 110 resulting in a
bearing position,
for example, within zero and 20 thousandths of an inch from this neutral axis.
The
location of the rotation axis 116 of the rotating body 110, given that its
length is often
measured in hundreds of feet and diameters as large as 25 feet, is difficult
to establish
to a resolution of a thousandths of an inch. Consequently measuring the
location of the
roller axis 172 as to being parallel to the rotation axis 116 is equally
difficult to establish.
Correct support roller alignment may provide mechanical reliability. Support
rollers such
as these, which may each carry a load of hundreds of tons and be as much as 10
feet in
diameter, it is only with a few thousandths of an inch bearing skew adjustment
168
which makes a difference between good operation and possible destruction.
[0058] Figures 5A, 5B, and 5C illustrate the rotating body 110 installed
on a slope
174. While three piers are shown, some kilns may have as many as 9 support
piers
with 9 pairs of support rollers while other units such as rotary dryers and
coolers may
have 2 piers.
[0059] No matter how carefully alignment measurements are made, problems
still
occur. The thrust forces 166 generated by badly aligned rollers 122 124 may be
underestimated, for example the thrust forces 166 can easily shatter end caps
2" thick.
Excessive thrust force 166 can also fracture bearing housings. Excessive
thrust force
166 can shear the hold down mechanism of the support bearing 142 and push the
bearing 142 off its base 150 axially. Excessive thrust force 166 is
particularly risky when
spherical roller bearings are employed.
CA 2972364 2017-07-05
- 12 -
[0060] The roller assembly uses the generated thrust force 166 generated
by
misalignment to push the roller 122 back to its neutral skew position
(parallel to rotation
axis 116). Since misalignment generates the thrust force 166, the thrust force
166 is
used to drive the roller 122 towards its neutral position. The more
misalignment the
greater is the driving force. Once the roller 122 reaches its neutral position
no thrust
force 166 is generated hence the roller 122 continually seeks its neutral
position.
[0061] Referring to Figure 6, illustrated therein is the roller
assemblies 118, 120
fitted with pivot plates 146, 148, in a left orientation, a centered
orientation, and a right
orientation. The rotation axis 116 of the kiln, the neutral axis of each
support roller 172,
176, and the pivoting action and direction 166 in response to skew conditions
are
shown.
[0062] On installation, the roller assembly 118, 120 most likely will be
in some
state of skew 168 (e.g., left orientation), generating the thrust force 166 on
the roller
assembly 118, 120. This thrust force 166 actively pivots the roller assembly
118, 120,
about the pivot pin 152, 154 towards its neutral position (e.g., centered
orientation)
along roller axis 172, 176, which, when reached, reduces the thrust force 166
to zero.
Should the skew 168 of the roller be opposite (e.g., right orientation), the
thrust force
166 will also be opposite and therefore move the roller to neutral (e.g.,
centered
orientation), as before.
[0063] Referring to Figures 7A and 7B, illustrated therein is the rotary
drum 100
without slope, set horizontally. Figure 7B may also be a close up view of, for
example,
Figure 8. The rotary drum 100 includes a pair of thrust rollers 178, 180
exhibiting gaps
182, 184 between the thrust rollers 178, 180 and the tire 112. The rollers
122, 124 are
set to neutral skew that it runs between the pair of thrust rollers 178, 180
(also
illustrated in Figure 5A).
[0064] With level units the rollers 122, 124 are purposely left running
in the
neutral position. The tire 112 runs between the left 178 and right 180 thrust
rollers such
that there are gaps 182, 184 present to either side of the tire 112.
[0065] Referring to Figure 8, illustrated therein the rotary drum 100
installed on a
slope 174 relative to the horizontal. The roller assembly 118 does not need
axial
CA 2972364 2017-07-05
- 13 -
balance, as the rollers 122 are set with neutral skew, and will run
continuously on the
downhill thrust roller 180.
[0066] With 100% thrust arrangements or hydraulic thrust rollers, which
are
installed on a slope 174, the rollers are still kept neutral but because of
gravity the
downhill thrust roller 180 will be in full contact and running continuously.
With these
designs there typically is no upper thrust roller (178).
[0067] Figure 9 illustrates an exaggerated illustration of tire 112
wobble or axial
run-out 186. Tolerance for axial run-out may be set at about 0.001 to 0.002
inches per
foot of tire diameter. For example, a 20' diameter tire may be expected to
have about
0.020" - 0.040" total axial run-out 186. Wobble of the tire 112 is usually
always present,
either due to allowable installation tolerance or due to non-uniform shell
temperature
profiles which, when present, causes the shell 110 to bend, if only
temporarily. The tire
112 being mounted on the shell 110 that has bends, transient or permanent,
will in turn
cause the tire 112 to wobble. As a result, the tire 112 rotation axis 116
constantly
changes during rotation. The pivoting roller assemblies 118, 120 mounted on
the pivot
plates 146, 148 allow the position of the roller axis 172 to dynamically
respond and
move with the tire rotation axis 116, constantly seeking to maintain a zero
thrust load.
[0068] Further, tires 112 are never mounted perfectly straight on the
shell 110
and the shell 110 can also develop bends in it. As a result, tires 112 exhibit
axial
wobble 186. With neutrally skewed rollers 122, 124 and with an unrestrained
pivot plate
146, 148 the roller assemblies 118, 120 will continually seek their neutral
position and
are therefore in constant motion to stay centered on the tire 112. Because the
shell 110
is not a level unit, gravity will cause the shell 110 to run downhill 174
thereby running
with full pressure on the downhill thrust roller 180.
[0069] Referring to Figure 10, illustrated therein is a shell 110
installed on a slope
174. Many units, kilns, rotary coolers, rotary dryers and so on are designed
to run with
axial balance. The roller assemblies 118, 120 each have an axial adjustor 188
to fix
any axial balance. The axial adjustor 188 is installed to fix the pivot plate
146, 148 for
each roller assembly 118, 120 such that the combined thrust generated by all
the roller
assemblies 118, 120 equals the gravitational pull on the unit downhill. This
provides the
CA 2972364 2017-07-05
- 14 -
ability to downsize the downhill thrust roller 180 and assembly, thereby
saving capital
cost of the equipment. Conversely, should the axial adjustor 188 on the pivot
plate 146,
148 be released, the roller assembly 118, 120 would re-align itself to its
neutral skew
axis.
[0070] The axial adjustor 188 locks the pivot plate 146, 148 with an
axial fixing
screw 190 to establish axial balance of the shell 110. Once the roller
assembly 118,
120 has pivoted on the pivot plate 146, 148 and the roller assembly 118, 120
has been
allowed to self-align the axial fixing screw 190 is engaged to lock the pivot
plate 146,
148 and incrementally add skew. Small adjustments are made by the axial fixing
screw
190 on each roller assembly 118, 120 sequentially and repeatedly until axial
balance is
attained and the rotation of the pivot plate 146, 148 is fixed in one rotation
direction.
Axial balance is attained when the thrust tire 112 is seen to momentarily lose
contact
with the downhill thrust roller 180 during each rotation. With only one axial
fixing screw
190 per roller assembly 118, 120 it is not possible to misadjust the roller
assemblies
118, 120 to add to gravitational push.
[0071] Alignment is greatly simplified because releasing the pivot plate
146, 148
causes the roller assembly 118, 120 to align itself. Small incremental and
sequential
skew is added to each roller until momentary lift-off from the downhill thrust
roller 180 is
achieved.
[0072] Referring to Figures 11A and 11B, illustrated therein is a support
assembly 300, similar in some aspects to the system of Figure 3 except having
sleeve
bearings 302 and button style thrust bearings 304 for a roller shaft 306 that
supports a
roller 308. Given the inevitable axial run-out of a tire 310, the roller shaft
306 is free to
travel back and forth axially along the sleeve bearings 302 with each rotation
of the tire
310. The distance between the left and right shaft thrust bearings 304 is
typically 1/4" to
1/2" greater than the length of the roller shaft 306. Since the axial run-out
of the tire 310
is expected to be an order of magnitude smaller, the axial travel 312 (e.g.,
from Figure
11A to Figure 11B) of the roller shaft 306 is not expected to cause a pivot
plate 314 to
move.
CA 2972364 2017-07-05
- 15 -
[0073] The support assembly 300 allows free axial travel of the roller
shaft 306 in
the sleeve bearings 302 when such are used with 100% thrust kilns. Tires 310
inevitably exhibit some axial run-out, which, when within tolerance, is
approximately
0.001" per foot of tire diameter. Given a tire 310 with 20 foot diameter will
mean an
axial wobble is approximately 0.020". The roller 308 fitted with the sleeve
bearings 302
and the pivot plate 314 will align itself such that the pivot plate 314
centers itself and
then stops moving. The sleeve bearing 302 allows the roller shaft 306 to float
0.020"
within the housings without causing the pivot plate 314 to move. This reduces
the
tendency to develop grooves and ridges between the roller shaft 306 and sleeve
bearings 302 thereby reducing the tendency to create hot bearings. This is a
further
benefit that may extend the service life of the support assembly 300.
[0074] Shaft thrust bearings or buttons 304, as illustrated, are one of a
few
different bearing configurations that exist. The principle of operation of
shaft thrust
bearings or buttons 304 and the function of the pivot plate 314 still applies
to this
embodiment.
[0075] Finally, if the support assembly 300 is used on 100% thrust or
hydraulic
thrust kilns with the sleeve bearings 302, axial adjustors (for example, axial
adjustors
188 of Figure 10) would not be necessary. 100% thrust kilns and kilns with
thrust rollers
fitted with hydraulic rams are designed to run with support rollers in their
neutral skew
position. Figures 11A and 11B show that the roller shaft would travel left
(Figure 11A)
to right (Figure 11B) or up-hill to downhill between but not necessarily
touching the shaft
thrust bearings 304, in phase with each shell rotation. As a result grooving
of the roller
shafts 306 and sleeve bearings 302 is minimized reducing the tendency to
create hot
bearings.
[0076] Referring to Figures 12A and 12B, illustrated therein is a close
up of
support assembly 118. The support assembly 118 supported by the pivot plate
146
enables a method that reveals the correctness of the support roller slope 172
or
inclination relative to the rotation axis. Where the drum 110 is installed on
an incline
174, the slope, which is typically in the range of 1% to 3%, each supporting
roller 118 is
on the same slope. Where the slope of the roller 172 and the slope of the drum
axis
CA 2972364 2017-07-05
- 16 -
116 are not the same, there may be a lack of sufficient face contact. As that
the
supporting load can be in hundreds of tons, any difference in slope increases
wear and
reduces service life. With the pivot plate that provides self-alignment of the
roller
assembly 118, the roller assembly 118 seeks and arrives in the neutral skewed
position.
In the neutral skew position and given that the rolling faces 126 of both
supporting roller
118 and supported tire 112 are designed to be flat and cylindrical (which will
be the
case for new and/or reconditioned equipment), any persistent lack of
uniformity of
contact from one side to other is caused where the roller slope 172 does not
match the
prevailing tire slope 116. This lack of uniformity creates a gap 199 between
the roller
118 and the tire 112. The gap 199 can be measured using a conventional feeler
gauge
and a calculated corrective shim 197 can be placed under the support roller
118.
[0077] The gap 199 prevails throughout rotation. When the pivot plate is
free to
move the roller 118 is in the self-aligned position. Given that the rotating
components,
both the tire 112 and the support roller 118, are in a new or reconditioned
state, that is
their contacting surfaces are both flat and cylindrical, any such gap 199
results when
the inclination of the roller 172 does not match the inclination of the tire
112. This gap
199 is measured and used to establish corrective measures. In the case of
spherical
roller bearings, the roller bearings include shims 197 to level the spherical
roller
bearings. In the case of larger kilns employing sleeve bearings (e.g. Figures
11A and
11B) shim 197 placement may not be possible and the roller support base 118 is
reset.
If the gap 199 is not removed, excessive wear and shortened service life of
the
components may occur at 195.
[0078] While the above description provides examples of one or more
apparatus,
methods, or systems, it will be appreciated that other apparatus, methods, or
systems
may be within the scope of the claims as interpreted by one of skill in the
art.
CA 2972364 2017-07-05
