Note: Descriptions are shown in the official language in which they were submitted.
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METHOD AND SYSTEM FOR RETREADING TRACK WHEEL
BACKGROUND OF THE INVENTION
The subject method and system for retreading a track wheel is generally
directed to reconditioning and/or reworking worn wheels for various vehicles
operated on track rails. The subject method and system provide for their
restoration,
such that the wheels may be re-used rather than discarded. More specifically,
the
subject method and system are directed to the 'retreading' of such a worn
track
wheel sufficient to reconstitute its original profile.
Railway-type track wheels such as these are used on various types of
vehicles, both powered and non-powered. Locomotives, railroad cars, cable
cars,
mining cars, wagons, coaches, and the like are but a few examples. In most
track
wheeled vehicles, power is applied by driving some or all of the track wheels,
with
traction relying on friction between the track wheel ¨ typically formed of
steel ¨ and
the railway tracks, which are typically also formed of steel or other metallic
material.
During the course of repeated use, the wheels of these vehicles and track
wheels wear out due to friction, slipping, and constant load against the
railway track.
Some track wheels tend to wear out more rapidly because they are typically
formed
of steel having a generally low Rockwell hardness as measured on a Rockwell
hardness Scale.
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Track wheels are typically formed of metallic material, such as steel. They
are formed generally with a tread portion that slightly tapers inward from an
outer
flange portion. This keeps laterally opposed wheels engaged on the rail tracks
they
ride on. However, there tends to be slippage between the flange of a given
wheel
and the track rail it engages, leading to pronounced wear of the wheel's
flange area.
The tread of the wheel also tends to wear from the lateral swaying of the
railway
vehicle which tends to result, especially when the vehicle travels at higher
speeds.
Other surfaces of the wheel may experience pronounced wear, depending on
the particular use to which it is subjected. For instance, track wheels often
encounter excessive wear at and around their exposed lateral side surfaces.
The
lateral side portions typically at both the flanged and opposing unflanged
sides of
the wheels tend to suffer premature wear due to repeated contact with
switching,
retarding, or other track mechanisms and hardware. In particular, those
surfaces
extending down from a tip of the flange down its side away from the tread
repeatedly encounter frogs, switches, and retarders on typical railways that
whose
abrasive contact eats away at the wheel surfaces there over time.
Typically, once the track wheel is worn at its various surfaces, as determined
by applicable safe operating standards ¨ such as for safe minimum thickness of
the
flange - the wheel is disposed of. It is not unusual for railroad maintenance
vehicles
to wear through multiple sets of wheels during a typical year of operation.
Invariably, this is at considerable replacement cost.
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As shown in FIG. 1, a track wheel 100 includes a flange 110 at one side and a
tread 120 having a tapered surface which extends from the flange to an
opposing
side 130. The flange 110 on the peripheral region of the track wheel 100 and
the
tapered tread 120 keep the track wheel from falling or sliding off the railway
tracks.
When a railway vehicle travels through a bend, the track wheel 100 does not
pivot
and displaces laterally off-center. The tapered profile of the tread acts as a
self-
centering correction mechanism to force the vehicle to travel true, but over
time, the
flange 110 and tread 120 surfaces wear out. Once worn, the track wheel 100
becomes unusable.
There are various systems known in the art relating to track wheels. For
example, US Patent 1,519,029 is directed to a process for renovating worn
flanged
wheels. This reference first mentions the method of turning down a steel
'tyre' in
which material is removed from the wheel to sculpt a new surface results in
loss of
valuable material. This method necessitated the need to match the wheel on the
opposing side of the axle with the same amount of material removed.
The reference prescribes filling of material from the worn-down contour line
B to the line E, then shaping the surface according to the prescribed contour
line D.
The approach is to keep quite close to the worn down tread so that the desired
shape
can be obtained with minimal cutaway of original material. The sectional
surface to
be obtained is limited on the one hand by B and E and on the other hand by D
and
comprises only a small fraction of that which would have had to be removed by
the
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prior method. Accordingly, waste of the wheel's costly material turned to
scrap is
minimized. However, the fill material is limited to the flange area E. Part of
the
wheel material is necessarily turned down thereafter to obtain the prescribed
contour
line D.
US Patent 6,746,064 is directed to a composite wheel for tracked vehicles.
The reference prescribes a wheel and flange of heat treated steel suitable for
a
particular end use. A portion of the inside surface of wheel flange, including
the
area of frictional contact between the wheel flange and rail, is machined
away. A
welded overlay of low friction material is applied to replace the material
removed
from an inside surface of flange.
Such known references, however, fail to provide a suitable system or method
for resurfacing a worn track wheel to reconstitute its various portions, such
as the
tread and flange surfaces, to their original profile as disclosed herein.
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SUMMARY OF THE INVENTION
It is therefore an object of this present invention to provide a wheel
resurfacing system and method for resurfacing a worn track wheel to its
original
profile.
This and other objects are attained by a wheel resurfacing system formed in
accordance with the present invention for resurfacing a worn track wheel
substantially to an original profile. The system comprises a support unit
holding the
worn track wheel, the worn track wheel having a circumferential surface
defining a
flange and a tread surface. The welding unit corresponds to said support unit
for
applying a welding material to the worn track wheel upon relative displacement
between the welding unit and the worn track wheel. A controller is coupled to
the
welding unit, the controller selectively actuates the welding unit to
adaptively
aggregate a plurality of annular beads of the welding material along the
circumferential surface to form a welded layer, with each annular bead
extending to
substantially encircle a portion of the circumferential surface. The welded
layer
thereby forms a curvilinear profile along the circumferential surface. A
surface
processing device is selectively actuated to smoothe the welded layer to form
a
substantially uniform surface to reconstitute the worn track wheel to the
original
profile.
In certain exemplary embodiments, a wheel resurfacing and fortifying system
for resurfacing a worn railway wheel substantially to an original profile is
provided.
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The system comprises a support unit holding the worn railway wheel, the worn
railway wheel having a circumferential surface defining flange and tread
regions
extending between laterally opposed side regions. A welding unit corresponds
to
the support unit for applying a welding material to the worn railway wheel
upon
relative displacement between the welding unit and the worn railway wheel, the
welding material having a Rockwell hardness greater than the worn railway
wheel.
A controller is coupled to the welding unit, which controller selectively
actuates the
welding unit to adaptively aggregate a plurality of annular beads of the
welding
material along the circumferential surface to form a welded layer. Each
annular
bead extends to substantially encircle a portion of the circumferential
surface. The
annular beads are disproportionately aggregated at preselected portions of the
circumferential surface, whereby the welded layer forms a curvilinear profile
tapered along the circumferential surface. A surface processing device
selectively
actuates to smooth the welded layer and form a substantially uniform surface
to
reconstitute the worn track wheel to the original profile.
In certain other exemplary embodiments, a method for resurfacing a
worn railway wheel substantially to an original profile is provided. The
method
comprises the step of supporting the worn railway wheel and a welding device,
whereby the worn railway wheel and the welding device rotate one relative to
the
other at a predetermined rate. Annular beads are formed from a welding
material
and adaptively aggregated along a circumferential surface of the worn railway
wheel
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to form a welded layer. The circumferential surface defines at least a flange
and a
tread surface, and each annular bead extends to substantially encircle a
portion of the
circumferential surface. The welded layer thereby forms a curvilinear profile
tapered along the circumferential surface. The welded layer is surface
processed to
define a substantially smooth surface contour and thereby substantially
reconstitute
the worn railway wheel to the original profile.
Those skilled in the art will appreciate the scope of the present invention
and
realize aspects thereof after reading the following detailed description of
the
preferred embodiments in association with the accompanying illustrative
figures.
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BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying illustrative figures incorporated in and forming part of
this specification depict several aspects of the invention, and together with
the
description serve to explain the principles of the invention.
FIG. 1 is a diagram illustrating an unused track wheel in accordance with an
exemplary embodiment of the present invention;
FIG. 2 is a diagram illustrating a profile of an unused track wheel in the
embodiment depicted in FIG. 1;
FIG. 3 is a diagram illustrating a worn track wheel in accordance with an
exemplary embodiment of the present invention;
FIG. 4A is a diagram illustrating a welding device reconstituting the worn
surfaces of the track wheel in accordance with an exemplary embodiment of the
present invention;
FIG. 4B is a diagram illustrating aggregated annular beads using the welding
device on the worn surfaces of the track wheel in the embodiment depicted in
FIG.
4A;
FIG. 4C is a diagram illustrating a welding device reconstituting the worn
surfaces of the track wheel in accordance with an alternate embodiment of the
present invention;
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FIG. 5 is a diagram illustrating transverse grooves on the circumferential
surface of the worn track wheel in accordance with an exemplary embodiment of
the
present invention;
FIG. 6A is a diagram illustrating a grinding wheel milling the aggregated
annular beads formed on the track wheel in the embodiment depicted in FIG. 4B;
FIG. 6B is a diagram illustrating a profile of the polished track wheel in the
embodiment depicted in FIG. 4B;
FIG. 7A is a diagram illustrating a system setup for resurfacing a worn track
wheel in accordance with an exemplary embodiment of the present invention;
FIG. 7B is an alternate embodiment of the system depicted in FIG. 7A;
FIG. 7C is a diagram illustrating annular beads being formed on a support
structure varying the angle of the worn track wheel; and
FIG. 8 is a diagram illustrating the step of reconstituting a worn track wheel
in accordance with one exemplary embodiment of the present invention.
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DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The embodiments set forth below represent the necessary information to
enable those skilled in the art to practice the invention and illustrate the
best mode of
practicing the invention. In light of the illustrated Figures and the
following
description, those skilled in the art will understand the concepts of the
invention and
recognize applications of these concepts not particularly addressed herein. It
should
be understood that these concepts and applications fall within the scope of
the
disclosure and accompanying Claims.
Wherever possible in the following description, similar reference numerals
will refer to corresponding elements on parts of different Drawings unless
otherwise
indicated.
Referring to FIGS. 1 and 2, there is a depiction of a new, unworn track wheel
100. FIG. 2 depicts a cut away section of a profile of the unworn track wheel
100;
the flange 110 is shown having an integral taper region 210 that tapers away
from
the flange 110. The integral taper region 210 extends from the flange 110 past
the
tread surface 120 (which extends to a lateral side 130) to cause a self-
centering
effect when a pair of opposing track wheels 100 comes down onto opposed rail
tracks, and also for lateral support on the on the tracks. The self-centering
effect
derives from the cradling that results between the rails when opposing
integral taper
regions 210 bearing down on the track rails. The track wheel 100 will wear
from
friction due to normal use, which includes self-centering and turning that
applies
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lateral pressure onto the integral taper region 210 extending between the
flange 110
and the tread surface 120. The frequency of use, type of application, and
hardness
properties of the track wheel determine the rate of wear of the integral taper
region
210 and tread surface 120.
Depending on the particular use to which it is subjected, the track wheel 100
tends to also experience pronounced wear at and around its exposed lateral
side
surfaces. That is, the circumferential peripheries of the side wall portions
outside
both the flange 110 and at the end of the tread surface 120 typically suffer
premature
wear due to repeated contact with switching, retarding, or other track
mechanisms
and hardware. Such track hardware is used to re-direct or brake rail cars by
applying, and maintaining as necessary, contact with one or both lateral sides
of the
rail cars' track wheels. The tip and wall surfaces of the track wheels at both
inner
and outer lateral sides the track wheels consequently encounter frogs,
switches, and
retarders on typical railways ¨ whose abrasive contact eat away at the wheel
surfaces there over time.
FIG. 3 depicts a worn integral taper region 210 that results in an acute taper
region 320, worn tread surface 330 and worn-out flange 310. The wheel's worn
areas typically also include the lateral side regions 350, 352 eaten away by
abrasive
contact with track hardware. In accordance with a preferred embodiment of the
invention, the acute taper region 320 and the tread surface 330, as well as
the worn
lateral side regions 350 and 352, are reconstituted. The worn-out flange 310,
acute
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taper region 320 and worn tread surface 330 create a potential hazard for any
railroad vehicle. The worn-out flange 310 becomes dangerously vulnerable to
cracking off, thereby causing the railroad vehicle to derail on a railway
track.
Applicable safety standards often determine how thick the worn-out flange 310
must
be for safe use. When the diameter of the flange 310 is measured and
determined
worn, the wheel can no longer be used safely, and is often disposed of. In
addition
to the compromised structural integrity caused by the worn-out flange 310, the
acute
taper region 320 and worn tread surface 330 lead to a more pronounced side-to-
side
swaying of the given railway vehicle. The side-to-side swaying motion
exacerbates
the wearing of the worn-out flange 310 and acute taper region 320 due to
frictional
heating. Due to its loss of tapering profile, a tread surface 330 that is worn
flat will
cease to provide the self-centering effect, causing the worn track wheel 300
to travel
off-center over a track rail. The worn-out flange 310 will then incur
prolonged
sliding contact with the edge of the rail. The worn lateral side regions
likewise pose
potential hazards to railroad vehicles for much the same reasons, in addition
to
degradation in responsiveness to switching, retarding, and other such track
control
mechanisms.
To reconstitute and rebuild the worn-out flange 310, acute taper region 320,
worn tread surface 330, and worn lateral side regions 350 and 352, the worn
track
wheel 300 is preferably sampled to determine the metallurgical properties of
the
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wheel. In accordance with a preferred embodiment, the metallurgical properties
of
the wheel are used to determine a welding rod having compatible properties.
Turning briefly to the flow of processes illustrated in FIG. 8, a worn track
wheel 300 may be resurfaced to reconstitute the wheel back to its original
profile
preferably according to the following steps. In Step 1, the worn track, or
railway,
wheel 300 is pre-conditioned for processing not only by being analyzed to
determine
its metallurgical properties, but also cleaned and, if necessary, subjected to
grinding
or suitable other preparatory treatment. This adapts the wheel surface for
further
treatment by removing impurities such as rust and debris formed or lodged in
the
surface of the wheel.
Preferably, the analysis of the wheel undertaken in Step 1 includes x-ray or
any other suitable imaging of the wheel's internal structure. This checks for
internal
cracks or other faults in the wheel's worn structure (not readily visible on
the
surface) which may compromise its structural integrity enough to preclude safe
re-
use, even in resurfaced and reconstituted form. Faulty wheels are thus
screened and
discarded as necessary.
Depending on the material composition of the wheel, moreover, Step 1 may
further include a pre-heating process, whereby the worn track wheel is
preheated to
a predetermined temperature (such as 500 to 700 F, for example). Such pre-
heating serves to prepare the wheel's metallic material for the welding
material,
making it more receptive to the new material (which has been selected in
suitable
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manner for material compatibility with the wheel). Especially where higher pre-
heating temperatures are used, pre-heating treatment of the worn wheel is
preferably
carried out in situ, with the wheel mounted in position on the given
support/table for
weld processing.
In Step 2, which may or may not be combined with Step 1 depending on the
requirements of a particular application, the wheel is mounted on a support or
table
(such as support 760 in FIGS. 7A-7B). The support/table holds the worn track
wheel for subsequent processing by a welding device. Either or both of the
track
wheel and welding device is rotated such that relative rotation is effected at
a
predetermined rate therebetween, preferably in controlled manner.
In Step 3, the wheel is weld-processed. As described in following
paragraphs, a plurality of annular beads of welding material are adaptively
aggregated in controlled manner upon a circumferential surface of the worn
track
wheel as it undergoes turning displacement relative to the welding device.
This
forms a welded layer having a suitable curvilinear profile tapering away from
the
wheel flange. Sufficient welding material is applied to form the welded layer
that
subsequent surface processing suitably removes just the newly-added layer,
rather
than diminishing any portion of the original/native material of the track
wheel. A
similar welding process is preferably carried out to so that the welded layer
extends
sufficiently to cover the worn lateral side regions of the track wheel.
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Preferably in Step 4, the weld-processed wheel is thermally 'decompressed'
to preserve its reconstituted structure. That is, the very hot, just weld-
processed
wheel is gradually lowered in temperature back to ambient ranges. A controlled
cool-down of the newly-reconstituted wheel reduces the potential for warping,
cracking, or other such effects of metal fatigue and the like, due to overly
rapid cool
down. Various processes may be used to control cool-down, such as progressive,
stepped decreases in the wheel's immediate thermal environment over a
predetermined time period. Suitable heating measures may be employed, for
example, to step the wheel's temperature down in stepped decrements from, say,
750 F-to-500 F-to 450 F-to 350 F-to 250 F-and so on down to ambient
temperature, with the temperature being maintained at each step for a certain
dwell
time, such as 20 or 30 minutes, as appropriate for the particular requirements
of the
intended application.
The controlled thermal environment may be provided in any suitable manner.
For example, the entire wheel support/table assembly may be disposed within an
oven-type assembly. Alternatively, one or more heating elements may be
disposed
about the mounted wheel to apply the required levels of controlled heating to
progressively lower the wheel's temperature.
In step 5, the weld-processed and sufficiently cooled wheel undergoes surface
processing to recover its original, unworn profile. Preferably, this includes
the use
of such things as a milling or grinding member to grind the welded layer down
to the
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required surface contour. In the disclosed example, a grinding stone is
employed to
form a substantially uniform, and even polished, surface which restores a like-
new
original profile for the wheel.
Turning back to FIGS. 4A and 4B, a welding device 410 is used to form weld
beads 430 on the worn track wheel 400. Weld beads 430 are formed by the
device's
suitably depositing welding material from its tip 440 as the worn wheel is
turned
relative to the device. In accordance with another aspect of the present
invention, the
weld beads 430 used to reconstitute the worn wheel 400 are preferably harder
(higher Rockwell) than the worn track wheel 400. While other suitable welding
processes may be employed, a submerged arc welding process is preferably
employed in the disclosed embodiment for maximum weld integrity. In this
process,
a wire-like rod of welding material 420 is fed through the device 410, along
with a
stream of granular flux material 420' (like sand or the like). The granular
flux
material 420' is fed in at a controlled rate to establish and maintain an
airtight flux
covering 425 about the welding point. The welding of weld bead 430 therefore
occurs submerged within this flux covering 425, such that the formation of
potentially harmful air pockets and the like in the resulting welded layer is
inhibited.
As the wheel is turned, granular flux material which falls from the wheel
after
forming the covering 425' is recovered and recycled back to the granular flux
feed
source, while the granular flux material 425' is continually replenished
through the
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device 410 to continually maintain the covering 425 about the instantaneous
welding
point.
One example of other alternative welding processes which may be employed
is illustrated in FIG. 4C. In this process, a shielded arc welding process is
employed
to preserve weld integrity. Examples of such processes include metal inert gas
(MIG) ¨ such as illustrated in FIG. 4C ¨ and Tungsten inert gas (TIG)
processes,
among others. As in the submerged arc welding process, a wire-like rod of
welding
material 420 in the illustrated embodiment is fed through a device 412, along
with a
stream of shielding gas flux material 430 passed through one or more
channel(s)
formed in device 412. The shielding gas flux material 430 is introduced at a
controlled rate to establish and maintain an airtight flux shield covering 435
about
the welding point. The welding of weld bead 430 therefore occurs shielded
within
this flux covering 435, such that the formation of potentially harmful air
pockets and
the like in the resulting welded layer is inhibited. As the wheel is turned
and
welding material 420 applied onto the welding point, the shielding gas flux
material
is continually fed from the shielding gas source and introduced through the
device
412 to continually maintain the shielding cover 435 about the instantaneous
welding
point.
Referring back to FIG. 4B, when welding the beads 430, a spin welding or
welding position manipulator is preferably used to set the wheel in a cradle
and
rotate in controlled manner, so that the welding beads 430, 450, 452 may be
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properly applied and aggregated over the wheel's worn regions. Otherwise, the
welding device 410 is controlled to let spin and/or rotate relative to the
wheel.
Alternatively, a combination of movements may be suitably employed for both
the
worn wheel 400 and the welding device 410.
As mentioned, the welding device 410 is coupled with a welding rod that is
electrically energized at the tip 440 to melt into the worn track wheel's 400
metal.
While the welding is taking place, the applied flux covering 425, 435 blankets
the
weld beads 430 to protect them from oxidation and contamination
In a preferred embodiment, the welding device 410 and the worn track wheel
400 rotate one relative to the other at a predetermined rate. The rate is
controlled by
an electronic controller that automatically adjusts the voltage, which is
directly
related to the length of the arc, and the current, which in turn affects heat
input.
During the welding process, as shown in FIG. 4B, the welding beads 430 are
adaptively aggregated by applying multiple passes of the welding device 410
over
the regions worn track wheel 400 so as to compensate for uneven wear at the
different worn regions of the wheel. This enables appropriate reconstitution
of the
worn-out flange 310 and acute taper regions 320, as well as the worn side
regions
350 and 352, so that the original profile of the integral taper region 210 on
a new,
unworn wheel may be recovered (see aggregated beads 430, 450, 452 at
respective
regions).
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As illustrated in FIG. 4B, particular area 320 and 352 of the worn track wheel
may require a greater accumulation of beads 430 than over its tread 330 or
outer side
350 of the flange. Simply applying the beads uniformly over all surfaces of
the
wheel would not sufficiently restore the original taper region 210 or full
wheel
profile. Suitable adaptive control of the welding process is maintained ¨ for
example, by accelerating weld bead formation over these areas 320, 350, or by
allowing for more passes (of the wheel past the device tip 440) - to form more
weld
beads 430 as necessary thereat.
It will normally be difficult to reconstitute the integral taper region 210
(and
other such excessively worn regions) in one pass, and multiple passes would be
necessary. An alternative approach would be to use a welding rod big enough to
fully cover the integral taper region 210 at once; however, it is not
economically
feasible. Moreover, the resultant heat is likely to be excessive, potentially
causing
unwanted effects on the wheel. In the disclosed embodiment, as each welding
bead
430, 450, 452 at the different regions is applied with a welding pass, the
welding
bead 430 substantially hardens before the next pass comes around. The next
pass
would thus move the welding device's tip 440 sufficiently to extend the area
of
coverage with the next applied bead.
In a preferred embodiment, the worn track wheel 400 is preheated to
approximately 500 F before the welding process. During the welding process,
air
pockets in the weld are mitigated. As mentioned, air pockets in the weld tend
to
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compromise the strength and integrity of the reconstituted wheel, leading to
premature chipping and cracking of the weld.
Depending on the specific requirements and resources of each particular
application, the amount of time incurred for each pass would vary accordingly.
In
certain embodiments, with certain types of wheels, 5-15 passes or bead layers
varied
according to the depth of the integral taper region 210 may be necessary to
build up
a suitable original profile.
While the term "bead" is used for convenience, the weld resulting from each
pass may not be in precisely beaded form. The weld would be applied preferably
with a steady contiguous forming of beads, with the next bead "melting" into
the
previously applied bead. A self-filling or self-leveling of the built-up weld
occurs
while preventing crevices as the weld material melts into the wheel.
In a preferred embodiment, such as illustrated in FIG. 5, a plurality of
grooves 530, or scoring notches, are formed on one or more surfaces of the
wheel.
For example, the contact surface of the worn track wheel 500 including the
tread
surface 520 and worn-out flange 510 are "scored" in this manner.
The grooves 530 may be mechanically or otherwise formed by a scoring unit
employing any suitable means known in the art. The grooves 530 are formed to
guard against de-lamination of the weld and to create better adhesion in the
restored
wheel. The grooves 530 which may be of any shape, contour, or configuration,
may
be transversely directed or otherwise oriented to have an angular displacement
off
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the central axis of the worn track wheel 500. As mentioned, an x-ray or other
suitable process may also be employed to check against cracks or air pockets
in the
weld which may threaten the integrity of the reconstituted wheel.
Proper care needs to be taken when pre-treating or scoring the surface of the
wheel so as not to compromise the structural integrity of the restored wheel.
Scoring could be detrimental to the structure or integrity of the worn wheel;
however, when appropriate measures are taken, like ensuring suitably limited
depth
and extent of the grooves 530 and how the grooves are made, the integral taper
region 210 and tread surface 520 may be reconstituted with better adhesion of
the
weld material than might otherwise result. This would contribute to a wheel
hardness level possibly even greater than that of the original track wheel
100.
In one preferred embodiment, after sufficient layers of welding beads 630
have been formed on the welded track wheel 600, the welded track wheel 600 is
then subjected to a grinding or other surface processing to smooth out its
profile.
Such a process is depicted in FIGS. 6A-6B. The surface processing preferably
employs a grinding stone 650 or a milling device which is brought down onto
the
welded track wheel 600. Preferably, the grinding stone 650 is spun, but the
welded
track wheel 600 may also or alternatively be spun. After a sufficient number
of
passes between the welded track wheel 600 and the grinding stone 650, a
virtually
factory-fresh, smooth, polished integral taper region 630c is formed.
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Depending on the requirements of a particular application, the welded track
wheel 600 may be subjected to heat treatment for further hardening. In any
event,
the processed wheel is preferably 'decompressed' thermally from its high
temperatures. This avoids the deleterious results of metal fatigue and the
like, by
effecting a gradual cool-down of the wheel as described in preceding
paragraphs.
FIG. 6B depicts welded track wheel 600 that includes notches or grooves 640
being covered by a first welded beads layer 630a and a second welded beads
layer
630b. Due to the grooves 640 on the contact surface of the welded track wheel
600,
the welded layer made up of several welded beads layer 630a, 630b shows a
contoured profile. The contoured profile is then ground by the grinding wheel
650 to
the polished edge profile 630c. A milling device may also be used to polish
the
second welded beads layer 630b to form a substantially uniform surface or
polished
edge layer 630c to reconstitute the track wheel's original integral taper
region 210.
During the welding process, the welded beads harden almost immediately
upon formation. Given the desired evenness and continuity of the welded beads,
the
precision and consistency of a welding machine is preferable. Robotic welders,
welding manipulators, CNC machines, or any other suitable equipment known in
the
art may be employed.
In a preferred embodiment as depicted in FIG. 7A, a manipulator or other
such device may be employed with a table 760 or other support for holding the
worn
track wheel 700 as a work piece and spinning the same relative to the welding
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equipment. One or more microprocessor based controllers may be operably
coupled
to the table 760 to precisely control the direction, range, angle, speed, and
such other
aspects of the worn track wheel's movement to effect the necessary passes as
the
weld is applied. The controller adaptively controls the welding unit to
account for
the uneven wear on the worn track wheel 700, adaptively aggregating the
annular
beads 780 at the intersecting area of the flange and tread surface sufficient
to
reconstitute the original wheel profile. Preferably, the controller speeds up
or slows
down the relative motion between the worn track wheel 700 and the welding
unit, or
selectively seeks out the area of the worn track wheel 700 needing more layers
of
annular beads 780.
In FIG. 7A, a welding unit is controlled by a controller applying weld
material to the contact surface of worn track wheel 700. The welding unit
includes a
welding device 710 and a flux applicator 720 applying welds in form of annular
beads 780 to the worn track wheel 700. In this preferred embodiment, the
welding
unit is stationary while the table 760 supporting the track wheel 700 rotates
in place.
FIG. 7B depicts an alternate embodiment having the supported wheel
stationary while the welding unit rotates in a circular path about the
supported track
wheel 700. In FIG. 7B, the supported track wheel 700 may or may not be
concurrently moved to effect the relative displacement necessary between the
welding device 710 and the track wheel 700 for successive welding passes.
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Other than the welding device structure 710, 720 shown, the welding device
employed may alternatively include a welding tip having hooked electrodes.
When
touched with a welding rod material, voltage and current controlled by the
controller
creates the electrical energy that melts the rod. The welding rod is typically
fed
from a rolled wire-loop batch.
At the time of welding, a separate flux applicator is then used to release
flux
material onto the annular beads 780. The flux produces a gas that forms a
gaseous
pocket around the welding point which seals out ambient air that could
otherwise
introduce impurities into the welded material. Much like the granular flux
covering
shown in the disclosed embodiment, the flux gas preserves a substantially pure
environment immediately about the welding point.
As illustrated in FIGS. 7A-7A, a system is formed that would generally
include: a welding unit loaded with sufficient supply of weld material that
includes
weld rods, and flux; a table 760 or other support for the workpiece or worn
track
wheel 700; a cooling unit for cooling the workpiece after applying the weld
material; and a controller for precisely determining and controlling the
applied
current and voltage outputted by the welding device 710. The cooling unit
operates
to maintain a safe temperature for the worn wheel 700 as welding is applied
and this
ensures that the wheel itself doesn't become deformed from heat. The cooling
unit
may employ any suitable means and medium known in the art, including
circulated
water or gas, heat conductance/sinking structures, and the like. In FIG. 7C, a
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structure may be employed that holds the worn track wheel 700 at an angle so
that
the weld material can be easily applied.
In one embodiment, the disclosed system is used as a wheel resurfacing
system for resurfacing a worn railway wheel 300 substantially to its original
profile
(integral taper region 210 and tread surface 120). A support 760 may be used
for
maintaining the worn track wheel 700. The track wheel 700 includes a
circumferential surface defining a first surface projecting or worn-out flange
110
from a second surface or tread surface 120. The welding device may include an
arc
welder.
In another embodiment, the disclosed system is used to also fortify and
resurface the worn track wheel 700 to its original profile. A welding material
having
a Rockwell hardness greater than the worn railway wheel 700 is selected in
forming
a welded layer by adaptively aggregating annular beads along the
circumferential
surface made up of worn-out flange 310, acute taper region 320 and worn tread
surface 330. For example, a typical rail wheel used in railroad maintenance
applications ranges in Rockwell hardness of 28-32 but welding material used
may
have a Rockwell hardness of greater than 42. The annular beads
disproportionately
aggregate at an intermediate contour between the worn-out flange 310 and acute
taper region 320, whereby the welded layer forms a curvilinear profile slanted
away
from the worn-out flange 310.
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In a preferred embodiment, a controller, which may be microprocessor
controlled, is programmed to selectively aggregate the annular beads at
specific
positions along the circumferential surface of the worn railway wheel 700. In
an
alternative embodiment, the controller is used to control the relative
displacement of
the worn railway wheel 700 to the welding device 710 so as to allow multiple
passes
of the welding device 710 over a previously welded annular bead which results
in
"stacking" of the annular beads. The controller may selectively control a
plurality of
parameters to adaptively aggregate the plurality of annular beads including a
predetermined rate of relative rotation between the welding unit and support
unit,
position of the welding unit, current and voltage of the welding device,
standoff of
the welding device, relative angle of the welding device to the worn wheel,
dwell
time of the welding device etc.
In another preferred embodiment, the metallurgical composition of the
railroad railway wheel 700 may be determined before the step of adaptively
aggregating the annular beads 780. A solvent may also be used to clean the
wheel
before adaptively aggregating the annular beads 780.
Although this invention has been described in connection with specific forms
and embodiments thereof, it will be appreciated that various modifications
other
than those discussed above may be resorted to without departing from the
spirit or
scope of the invention as defined in the appended claims. For example,
functionally
equivalent elements may be substituted for those specifically shown and
described,
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certain features may be used independently of other features, and in certain
cases,
particular locations of elements, steps, or processes may be reversed or
interposed,
all without departing from the spirit or scope of the invention as defined in
the
appended claims.
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