Note: Descriptions are shown in the official language in which they were submitted.
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Description
WEAR COMPONENT FOR COMPACTOR WHEEL
Cross-Reference to Related Application
This application claims the benefit of U.S. Provisional Patent
Application No. 61/809,018, filed April 5, 2013.
Technical Field
The present disclosure relates generally to wear components and,
more particularly, to wear components for compactor wheels.
Background
Compactors such as, for example, landfill compactors and soil
compactors typically include steel wheels, which are fitted with teeth that
extend
radially outward from the wheels to engage and compact material over which the
compactors are driven. Over time, the teeth wear down, and they eventually
need to be replaced.
U.S. Patent No. 6,632,045 to McCartney ("the '045 patent")
discloses an exemplary tooth. The tooth of the '045 patent is a two-part tooth
that is adapted to be welded to a steel wheel. It includes a base constructed
from
a weldable material, and a cap constructed of a harder metal than the metal
used
for the base. According to the '045 patent, the tooth is manufactured by
casting
the base in a first mold, moving the base to a second mold, and casting the
cap
onto the base in the second mold. When casting the cap, molten metal flows
into
mating formations of the base, ensuring that the cap is firmly keyed to the
base
when the molten metal solidifies.
While the tooth of the '045 patent may be appropriate for certain
applications, it may not be well-suited for others. For example, the tooth of
the
'045 patent may not be well-suited for applications in which its weight
stresses
drivetrain components of a compactor without meaningfully improving
compaction. In such applications, the tooth might cause premature failure of
the
drivetrain components, thereby unnecessarily increasing maintenance costs
associated with the compactor.
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The various embodiments of the present disclosure are directed
toward overcoming one or more deficiencies of the prior art.
Summary
In an exemplary embodiment of the present disclosure, a wear
component includes a base portion and a tip portion. The tip portion includes
a
proximate end and a distal end. The proximate end is metallurgically bonded to
the base portion at a base-tip interface, which has a generally parabolic
cross-
sectional profile. The distal end defines an exterior surface of the wear
component.
In another exemplary embodiment of the present disclosure, a
wear component includes a base portion and a tip portion. The tip portion
includes a proximate end, a distal end, and an at least partially concave side
surface extending from the distal end to the proximate end. The proximate end
is metallurgically bonded to the base portion at a base-tip interface. The
distal
end defines an exterior surface of the wear component.
In yet another exemplary embodiment of the present disclosure, a
wear component includes a base portion and a tip portion. The base portion
includes a plurality of protrusions. The tip portion includes a proximate end
and
a distal end. The proximate end includes a plurality of recesses, and is
metallurgically bonded to the base portion at a base-tip interface, where the
plurality of protrusions extends into the plurality of recesses. The distal
end
defines an exterior surface of the wear component.
Brief Description of the Drawings
Fig. 1 is a pictorial illustration of an exemplary wheel for use
with a compactor;
Fig. 2 is a pictorial illustration of an exemplary wear component
for use with the wheel of Fig. 1;
Fig. 3 is a magnified cross-sectional view of an exemplary
interface between exemplary tip and base portions of the wear component of
Fig.
2;
Fig. 4 is a cross-sectional view of an exemplary apparatus for
casting the wear component of Figs. 2 and 3;
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Fig. 5 is a cross-sectional view of the wear component of Figs 2-4
in an exemplary mold of the apparatus of Fig. 4;
Fig. 6 is a pictorial illustration of another exemplary tip portion;
Fig. 7 is a cross-sectional view of the tip portion of Fig. 6 bonded
to another exemplary base portion;
Figs. 8-13 are pictorial illustrations of yet further exemplary tip
portions; and
Figs. 14 and 15 are flow charts describing exemplary disclosed
methods of casting articles of manufacture, such as the wear components of the
other figures.
Detailed Description
Fig. 1 illustrates a steel wheel 10 for use with a mobile machine,
such as a landfill or soil compactor. As shown, wear components 20 in the form
of teeth are fitted to wheel 10, and extend radially outward from wheel 10 to
engage and compact material over which wheel 10 is driven. It should be
understood, however, that wear components 20 may be teeth that are fitted to
another type of part (e.g., a bucket) or may be another type of wear component
entirely (e.g., hammers on disk rotors of a scrap metal shredder). In any
case, in
certain embodiments (e.g., the embodiment of Fig. 1), each wear component 20
may include a tip portion 30 that extends radially outward from wheel 10 to
engage and compact material over which steel wheel 10 is driven. In these
embodiments, tip portion 30 may be connected to wheel 10 by a base portion 40
of its wear component 20, which may be welded to wheel 10.
Tip portion 30 may have a distal end 50 defining an exterior
surface of its wear component 20. As shown in Fig. 1, distal end 50 may be
generally 1-shaped. It should be understood, however, that distal end 50 may
be
otherwise shaped. For example, distal end 50 may be generally +(plus)-shaped.
Alternatively, distal end 50 may have another shape conducive to compacting
material. Tip portion 30 may also include side surfaces 60 extending from
distal
end 50 to a proximate end 70 of tip portion 30. In certain embodiments, side
surfaces 60 may be at least partially concave, enabling them to deflect
material
away from base portion 40 and thereby protect base portion 40 from wear.
Alternatively, side surfaces 60 may have other shapes that are conducive to
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compacting material (e.g., shapes that are not at least partially concave).
Regardless of tip portion 30's shape, tip portion 30 may be formed from a
material with a hardness of at least 45 Rockwell C, making it highly resistant
to
abrasion resulting from compaction of material. For example, tip portion 30
may be formed from white iron (e.g., high-chromium white iron or Ni-Hard),
carbidic iron, austempered iron, high-carbon steel, high-carbon alloy steel,
tool
steel, carbidic steel, or stainless steel.
Referring to Fig. 2, base portion 40 may include a mounting end
75 for attaching wear component 20 to wheel 10, a distal end 77 opposite
mounting end 75, and side surfaces 78 extending from mounting end 75 to distal
end 77. As shown, mounting end 75 is generally shaped to follow a contour of
wheel 10, thereby facilitating the attachment of wear component 20 to wheel
10.
Notably, however, mounting end 75 may include a recess 80, which does not
follow the contour of wheel 10. Recess 80 may become a hollow cavity when
wear component 20 is attached to wheel 10, thereby reducing the weight of wear
component 20 relative to a similarly sized (but solid) wear component. Base
portion 40 may be formed from a material with a carbon-equivalent (CE) value
of less than 0.7, ensuring that it can be welded to steel (e.g., steel wheel
10)
using portable welding equipment in the field (as opposed to specialized
welding
procedures typically required to be performed in a maintenance facility). For
example, base portion 40 may be formed from steel (e.g., carbon steel, alloy
steel, or stainless steel).
Base portion 40 may be metallurgically bonded to tip portion 30,
that is, portion 40 may be attached to portion 30 primarily by metallurgical
bonding. In particular, distal end 77 of base portion 40 may be
metallurgically
bonded to proximate end 70 of tip portion 30. As shown in Fig. 3, the
interface
between distal end 77 and proximate end 70 ("base-tip interface 100") may thus
be composed solely of a mixture of the material of base portion 40 and the
material of tip portion 30. That is, base-tip interface 100 may include no
adhesive or filler metal, no oxide films, and no voids.
The shape of base-tip interface 100 (and thus distal end 77 and
proximate end 70) may be non-planar, and may be related to the method by
which wear component 20 is cast. For example, referring to Fig. 4, wear
component 20 may be centrifugally cast using a dual-pour method in which
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molten first and second materials are poured through a funnel 120 into a
rotating
mold 110. The molten first material may be poured first to form tip portion 30
while mold 110 is rotated at a first speed. After allowing the first material
to
cool, the second material may then be poured over the first material (now tip
portion 30) to form base portion 40 while mold 110 is rotated at a second
speed,
which may or may not be the same as the first speed. Both pours may take place
while mold 110 is rotated about an axis 115 that is generally parallel to a
direction of gravitational acceleration (i.e., a direction in which the
materials fall
as they are poured). Such rotation may cause the first material to creep up
the
sides of mold 110, thereby giving proximate end 70 of tip portion 30 (and thus
also base-tip interface 100) a generally parabolic cross-sectional profile, as
shown in Fig. 4. It should be noted that, below base-tip interface 100, tip
portion
30 may have a solid (i.e., free of voids) cross-section that is perpendicular
to axis
115, as shown in Fig. 5. Further, it should be understood that the shape of
the
outer edge 125 of any cross-section of tip portion 30 that is perpendicular to
axis
115 will be defined by the shape of mold 110. Thus, outer edge 125 may be
non-circular, as shown in Fig. 5. For example, outer edge 125 may be generally
I-shaped (as illustrated), generally +(plus)-shaped, or otherwise shaped.
In another method of centrifugally casting wear component 20,
tip portion 30 may be cast, forged, or machined from a first material before
being positioned within mold 110. A molten second material may then be
poured into mold 110 over tip portion 30 to form base portion 40, while mold
110 is rotated about axis 115. With this second method, proximate end 70 of
tip
portion 30 may begin with almost any shape. Proximate end 70's shape may
change slightly during molding as a result of the metallurgical bonding
process,
but it should be understood that the shape of base-tip interface 100 may at
least
generally track the beginning shape of proximate end 70. For example, as shown
in Fig. 6, proximate end 70 may begin with a plurality of recesses 130
extending
from a first side 140 of tip portion 30 to a second side 150 of tip portion
30.
Each recess 130 may be generally valley-shaped. For example, each recess 130
may be generally U-shaped, and may be wider than it is deep (as illustrated in
Fig. 6). In certain embodiments, proximate end 70 may begin with two recesses
130. Referring to Fig. 7, when the molten second material is poured into mold
110 over such recesses 130, the second material may slightly deform recesses
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130 into recesses 130'. The second material may then solidify to form base
portion 40 with a plurality of protrusions 160, each extending into a
corresponding one of recesses 130' at base-tip interface 100. It should be
noted
that, in some embodiments, protrusions 160 and recesses 130' may mechanically
enhance the bond of base portion 40 to tip portion 30.
The number, shape, and placement of any protrusions 160
extending into proximate end 70 of tip portion 30 at base-tip interface 100
may
be affected by the beginning shape of proximate end 70. For example, rather
than beginning with recesses 130 that are wider than they are deep (as
illustrated
in Fig. 6), proximate end 70 may begin with recesses 130 that are deeper than
they are wide. As another example, rather than beginning with recesses 130
that
are generally U-shaped (as illustrated in Fig. 6), proximate end 70 may begin
with recesses 130 that are generally V-shaped. Alternatively, as illustrated
in
Fig. 8, proximate end 70 may begin with recesses 230 that are generally box-
shaped. In yet another alternative embodiment, rather than beginning with a
plurality of recesses 130 or 230 (as illustrated in Figs. 6 and 8), proximate
end
70 may begin with a single recess 330, as shown in Fig. 9.
Alternatively, as illustrated in Fig. 10, proximate end 70 may
begin with a plurality of recesses 430 in the form of rabbets (i.e., step-
shaped
recesses) in outer edges 435 of tip portion 30. While Fig. 10 illustrates
recesses
430 as extending only from first side 140 to second side 150, recesses 430 may
also extend from a third side 440 of tip portion 30 to a fourth side 450 of
tip
portion 30, as shown in Fig. 11.
In yet another alternative embodiment, as shown in Figs. 12 and
13, proximate end 70 may begin with one or more recesses 530 in the form of
bathtub-shaped depressions. While such recesses 530 could be the only recesses
in proximate end 70, proximate end 70 could also include one or more of the
recesses discussed above. For example, as shown in Fig. 13, proximate end 70
may include two recesses 530 and four recesses 430. In fact, it should be
understood that proximate end 70 may include any combination of any number
of recesses 130, 230, 330, 430, 530, and/or any other similarly shaped
recesses.
Figs. 14 and 15 arc flow diagrams describing exemplary methods
of casting articles of manufacture such as wear components 20, and they will
be
discussed in the following section.
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Industrial Applicability
The disclosed wear components may be fitted to steel components
and may be particularly beneficial when fitted to steel wheels of landfill or
soil
compactors. The wear components may be cast such that they facilitate in-field
(as opposed to in-maintenance facility) maintenance of the compactors and also
minimize the amount of maintenance the compactors require. Exemplary
methods of casting articles of manufacture, such as the disclosed wear
components, will now be described.
Referring to Fig. 14, wear component 20 may be centrifugally
cast using a dual-pour method in which molten first and second materials are
poured into mold 110 while mold 110 is rotated about axis 115 (referring to
Fig.
4) (step 1400). First, a molten first material may be poured through funnel
120
into mold 110 to form tip portion 30 while mold 110 is rotated at a first
speed
(step 1410). The first material may have a hardness of at least 45 Rockwell C,
making tip portion 30 highly resistant to abrasion resulting from compaction
of
material and thereby reducing the number of times wear component must be
replaced. For example, as discussed above, the first material may be white
iron
(e.g., high-chromium white iron or Ni-Hard), carbidic iron, austempered iron,
high-carbon steel, high-carbon alloy steel, tool steel, carbidic steel, or
stainless
steel. While funnel 120 may be positioned such that the first material is
poured
at a fixed location relative to axis 115 (e.g., along axis 115), funnel 120
may
alternatively be moved during the pouring such that the first material is
poured at
a plurality of different locations relative to axis 115. In any case, the
rotation of
mold 110 may cause the first material to creep up the sides of mold 110,
thereby
giving proximate end 70 of tip portion 30 (and thus also base-tip interface
100) a
generally parabolic cross-sectional profile, as shown in Fig. 4. Such a
profile
may enable the first material to protect a large portion of the exterior
surface of
wear component 20 without occupying a correspondingly large portion of the
volume of wear component 20, thereby minimizing the amount of the first
material (which may be more costly than the second material) required to form
wear component 20.
Next, the first material may be allowed to cool (step 1420). A
molten second material may then be poured through funnel 120, into mold 110,
over the first material (now tip portion 30) to form base portion 40 while
mold
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110 is rotated at a second speed, which may or may not be the same as the
first
speed (step 1430). The second material may have a carbon-equivalent (CE)
value of less than 0.7, ensuring that base portion 40 can be welded to steel
(e.g.,
steel wheel 10) using portable welding equipment in the field (as opposed to
specialized welding procedures typically required to be performed in a
maintenance facility). For example, as discussed above, the second material
may be carbon steel, alloy steel, or stainless steel. While funnel 120 may be
positioned such that the second material is poured at a fixed location
relative to
axis 115 (e.g., along axis 115), funnel 120 may alternatively be moved such
that
the second material is poured at a plurality of different locations relative
to axis
115. Notably, the rotation of mold 110 may cause the second material to move
radially outward along a surface of the first material when the second
material
impacts the first material, displacing any foreign materials (e.g., oxide
films) on
the surface of the first material. The second material may then
metallurgically
bond base portion 40 to tip portion 30. The rotation of mold 110 may also
cause
the second material to creep up the sides of mold 110, facilitating the
formation
of recess 80 in mounting end 75 of base portion 40. This recess 80 may, in
turn,
become a hollow cavity when wear component 20 is attached to wheel 10,
thereby reducing the weight of wear component 20 relative to a similarly sized
(but solid) wear component. Such weight reduction may minimize stresses on
drivetrain components of compactors using wear components 20, thereby
extending the life of the drivetrain components and reducing maintenance costs
associated with the drivetrain components. Additionally, the weight reduction
may minimize the amount of fuel required to operate the compactors, thereby
reducing operating costs associated with the compactors.
In alternative embodiments and referring to Fig. 15, wear
component 20 may be centrifugally cast using a tip portion 30 that is cast,
forged, or machined from the first material before being positioned within
mold
110 (step 1500). In particular, tip portion 30 may be positioned with its
proximate end 70 facing upward such that any material poured over tip portion
30 is poured over proximate end 70. Then, while rotating mold 110 about axis
115 (step 1510), the molten second material may be poured into mold 110 over
tip portion 30 to form base portion 40 (step 1520). Although funnel 120 may be
positioned such that the second material is poured at a fixed location
relative to
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axis 115 (e.g., along axis 115), funnel 120 may alternatively be moved such
that
the second material is poured at a plurality of different locations relative
to axis
115. Notably, the rotation of mold 110 may cause the second material to move
radially outward along proximate end 70 when the second material impacts the
first material, displacing any foreign materials (e.g., oxide films) on
proximate
end 70. In some embodiments, the movement may be at least partially guided by
recesses 130, 230, 330, 430, and/or 530 of proximate end 70, potentially
speeding up and/or slowing down the movement, and thereby maximizing the
displacement of foreign materials. The second material may then
metallurgically
bond base portion 40 to tip portion 30. The rotation of mold 110 may also
cause
the second material to creep up the sides of mold 110, facilitating the
formation
of recess 80 in the same way as discussed above with respect to the dual-pour
method.
It will be apparent to those skilled in the art that various
modifications and variations can be made in the disclosed wear components
without departing from the scope of the disclosure. Other embodiments of the
disclosed components will be apparent to those skilled in the art from
consideration of the specification and practice of the components disclosed
herein. It is intended that the specification and examples be considered as
exemplary only, with a true scope of the disclosure being indicated by the
following claims and their equivalents.
