Note: Descriptions are shown in the official language in which they were submitted.
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MAIN BODY CORE SET ASSEMBLY AND CORE BOX
FOR A COUPLER BODY
REFERENCE To EARLIER FILED APPLICATION
[001] This application claims the benefit of the filing date of United
States Patent Application Number 13/337,558, filed December 27, 2011, the
disclosure of which is incorporated, in its entirety, by this reference.
BACKGROUND
1. Technical Field
[002] The present embodiments relate generally to the field of cores
used in railroad coupler casting, and more specifically, to a main body core
set assembly and core box that uses a plug in a pattern of the core box to
form a head core with a connection joint adaptively insertable into a shank
core different than the shank core normally formed integral with the head
core.
2. Related Art
[003] Railcar couplers are used to couple railcars together. Typical
couplers used throughout North America are the Type-E and Type-F
couplers, also referred to as SBE60 and 5BE69 or E69 couplers,
respectively. These couplers are normally produced through a green sand
casting process, which offers a low-cost, high-production method for forming
complex shapes. While the heads of these couplers are identical, the
shanks differ. The Type-E shank is shorter and tapers while the Type-F
shank remains about the same width and is much longer. Figures 3A and
3B show how the shanks of these two couplers differ while the heads are the
same except. The guard arm piece in Figure 3A attaches and is therefore
not cast with the head. Accordingly, the Type-E and Type-F heads are
identical or substantially identical.
[004] In sand casting, a mold is created using a sand and binder mixture
(i.e., molding sand). The binder allows the sand to retain a shape. The
most common sand/binder mixture used for casting couplers is green sand,
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which consists of silica sand, organic binders and water. Green sand is
used primarily due to its lower cost.
[005] The mold typically comprises a cope portion (i.e., top half) and a
drag portion (i.e., bottom half), which are separated along a straight or
offset
parting line. To form the cope and drag portions, patterns that define the
cope and drag portions, respectively, of the coupler and a gating system are
placed into separate flasks (or mold boxes). Cores that will be used to
define the inner and exterior surfaces of the coupler casting may also be
molded from patterns in respective halves of mold boxes in a separate
lo molding process.
[006] Molding sand is then packed around the patterns, to define mold
cavities for the coupler and gating system, or in the case of cores, to define
the features of the cores that will be used to define the inner and exterior
surfaces of the coupler. Draft angles of three (3) degrees or more are
machined into the pattern to ensure the pattern releases from the mold.
[007] As mentioned, the molding process may be used to create cores
to define the inside of the main body of the coupler. Even though the heads
of the Type-E and Type-F couplers are identical, the main body cores for the
Type-E and Type-F couplers are conventionally formed in different mold
boxes because the Type-E main body core is formed with a head core
integral with a shank core and the Type-F head core is formed separate from
a longer shank core. Using different mold boxes for forming the Type-E and
Type-F main body cores is inefficient in the manufacturing process.
Furthermore, the Type-F shank is conventionally set independently and not
locked to the head core, resulting in internal fins at the head- to-shank
joint
which sometimes results in a T-section internal to the shank. A T-section is
undesirable because it affects the solidity of the corresponding part of the
casting and can result in hot tears at the bottom of the horn-to-shank
interface of the coupler.
[008] After the patterns are removed from the main body coupler mold,
the cores are placed into the mold (between the cope and drag portions).
The mold is then closed and filled with hot liquid metal, which is poured into
the mold via a down sprue. After the metal has been poured into the mold,
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the casting cools and contracts as it approaches a solid state. Risers, which
are reservoirs of molten material, are placed at those areas of the casting
that exhibit the highest contraction. The risers feed those areas as the
casting cools to help minimize the formation of voids, which would otherwise
occur. The risers are formed in the cope portion and can typically define
openings, which allow gases to escape during pouring and cooling.
[009] After solidification, the solidified metal (e.g., raw casting)
is
removed by breaking away the mold. The casting is then finished and
cleaned via grinding, blasting, welding, heat treatment, or machining. These
casting techniques have several disadvantages. The binders used in the in
the molding sand can have a significant effect on the final product, as they
control the dimensional stability, surface finish, solidification, and casting
detail achievable in each specific process. In particular, couplers cast in
green sand having a relatively poor dimensional stability and surface finish.
These couplers may also exhibit a higher rate of defects due to solidification
issues.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The system may be better understood with reference to the
following drawings and description. The components in the figures are not
necessarily to scale, emphasis instead being placed upon illustrating the
principles of the invention. Moreover, in the figures, like-referenced
numerals designate corresponding parts throughout the different views.
[0011] Figure 1 is a perspective view of a set of cores, including a
main
body core, for use in casting a Type-E (SBE60) railcar coupler.
[0012] Figure 2 is a perspective view of a set of cores, including main
body and shank cores, for use in casting a Type-F (E69) railcar coupler.
[0013] Figure 3A is a perspective view of a main body of a Type-E
coupler.
[0014] Figure 3B is a perspective view of a Type-E head and Type-F
shank of a railcar coupler.
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[0015] Figure 4A is a perspective view of one half of a mold box and
pattern for forming a Type-E main body core.
[0016] Figure 4B is a perspective view of the opposite half of the
mold
box and pattern shown in Figure 4A showing sliding insert pieces that create
apertures used to form the lock guide and thrower lug.
[0017] Figure 4C is a perspective view of the mold box and pattern of
Figure 4A, with a plug inserted in the pattern such as to truncate the shank
core portion, and thus create a Type-E head mold adaptable for a Type-F
shank core for casting a coupler.
[0018] Figure 4D is a perspective view of the mold box and pattern of
Figure 4B, with a plug inserted to truncate the shank core portion together
with the plug of Figure 4C, and showing the same sliding insert pieces as
Figure 4B.
[0019] Figure 5A is a perspective view of the plug shown in Figure 4C.
[0020] Figure 5B is a perspective view of the plug shown in Figure 4D.
[0021] Figure 6 is a perspective view of a Type-E main body core that
results from the mold boxes and corresponding patterns of Figures 4A and
4B.
[0022] Figure 7 is a perspective view of a Type-E head core adapted
for
a Type-F shank core, where the shank core is truncated with use of the
plugs in the pattern mold as shown in Figures 4C and 4D.
[0023] Figure 8A is a perspective view of a Type-E head core adapted
for
use with a Type-F shank core from a different angle than that of Figure 7
with a male connector.
[0024] Figure 8B is a perspective view of a female connector of a shank
core into which the male connector of the adapted head core of Figure 8A
may be inserted.
[0025] Figure 8C is side view of the male connector of Figure 8A,
showing exemplary dimensions.
[0026] Figure 8D is a plan, end view of the female connector of Figure
8B.
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[0027] Figure 9A is a perspective view of an exemplary shank core to
which the male connection joint of the adapted head core of Figure 8A may
be inserted.
[0028] Figure 9B is a perspective view of the adapted head core of
Figure
5 8A attached to the shank core of Figure 9A.
[0029] Figure 9C is a cross-section view of Figure 9B showing a tight-
fitting connection joint between the adapted head core of Figure 8A and the
shank core of Figure 9A.
[0030] Figure 10 is a side, perspective view of a Type-E head core
adapted for a Type-F shank core showing angles of insertion and removal of
insert pieces shown in Figures 4B and 4D.
[0031] Figure 11A is a cross-section, perspective view of a first half
a
coupler head and shank showing a lock guide inside the coupler head.
[0032] Figure 11B is a cross-section, perspective view of a second
half of
the coupler head and shank of Figure 11A, showing a thrower lug inside on
the coupler head.
[0033] Figure 12 is a flow chart of a method for creating a main body
core
for casting a coupler body of a railcar coupler.
DETAILED DESCRIPTION
[0034] In some cases, well known structures, materials, or operations are
not shown or described in detail. Furthermore, the described features,
structures, or characteristics may be combined in any suitable manner in
one or more embodiments. It will also be readily understood that the
components of the embodiments as generally described and illustrated in
the Figures herein could be arranged and designed in a wide variety of
different configurations.
[0035] This application is related to U.S. Patent Application Serial
No.
13/339,007, filed December 28, 2011, and entitled "Method and System for
Manufacturing Railcar Couplers," which is hereby incorporated by this
reference in its entirety.
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[0036] Figure 1 shows a set of cores 10 for use in casting a Type-E
(SBE60) railcar coupler 244 (Figure 3A). The set of cores 10 may include,
but is not limited to, a main body core 100, a cotter hole core 104, a lower
shelf core 108, an upper guard arm core 112, a lower guard arm core 116, a
hose support lug core 120, a rotary shaft core 124, a gating core 130, a slot
core 134 and a butt end core 138. As discussed earlier, these cores are
placed inside cope and drag mold portions that are used to cast the coupler.
The Type-E railcar coupler 244 shown in Figure 3A is the product of the
casting. The main body core 100 includes an integrated shank core 102
lo portion of the main body core 100.
[0037] Figure 2 shows a set of cores 20 for use in casting a Type-E/F
(E69) railcar coupler 254 (Figure 3B). The set of cores 20 may include, but
not be limited to, a main body (or head) core 200, a shank core 204
including a shank core cope side 205 and a shank core drag side 207, an
upper guard arm core 212, a lower guard arm core 216, a hose support lug
core 220, a rotary shaft core 224, a gating core 230, a rear pin hole core 234
and a spherical butt end core 238. As discussed earlier, these cores are
placed inside the cope and drag mold portions before casting. The Type-E/F
railcar coupler 254 shown in Figure 3B is the product of the casting. The
shank core 204 is separate from the head core 200 in Figure 2, but has been
attached to the head core 200 as will be explained herein. As discussed
with reference to the related art, the head core and shank cores 200 and 204
are conventionally set independently and not locked to each other, resulting
in internal fins at the head-to-shank joint which sometimes results in a T-
section internal to the shank. A T-section is undesirable because it affects
the solidity of the corresponding part of the casting and can result in hot
tears at the bottom of the horn-to-shank interface.
[0038] Figures 4A and 4B display, respectively, a first mold box 300
defining a first pattern 301 and a second mold box 310 defining a second
pattern 311 for forming the main body core 100 (Figure 6) used to cast the
Type-E railcar coupler shown in Figure 3A. The first and second patterns
301 and 311 will define the outer surface of the main body core and are not
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identical because the main body core 100 is not symmetrical about its center
parting line.
[0039] Each pattern 301 and 311 defines a first slot 302 and a second
slot 306. A lock guide insert piece 304 is slidably attached to the first slot
302 of at least one of the patterns such that the lock guide insert piece 304
may be inserted and withdrawn before and after molding in a semi-
automated fashion. The action can be semi-automated because the angle
and placement of the lock guide insert piece 304 is precise as guided by the
first slot 302, but may still be positioned manually by either inserting or
lo removing the lock guide insert piece 304. The lock guide insert piece
304
forms an aperture 346 (Figure 6) in the main body (or head) core that will
form a lock guide 340 (Figure 11A) of the coupler head during casting. The
lock guide insert piece 304 slides along the first slot 302 at an approximate
90-degree angle with respect to an axis 345 (Figure 10) formed through the
longitudinal center of each pattern (and head core), e.g., with respect to the
longitudinal center of a shank portion 312 of each pattern. Figure 10 best
shows this angle as the lock guide insert piece 304 is illustrated with
reference to the head core 200 and the axis 345 without the mold box or
pattern.
[0040] A thrower lug insert piece 308 is slidably attached to the second
slot 306 of at least one of the patterns such that the thrower lug insert
piece
308 may be inserted and withdrawn before and after molding in a semi-
automated fashion. The thrower lug insert piece 308 forms an aperture 348
(Figure 7) in the main body (or head) core that will form a thrower lug 350
(Figure 11B) of the coupler head during casting. The thrower lug insert
piece 308 slides along the second slot 306 at an approximate 45-degree
angle (Figure 10) with respect to the axis 345 formed through the
longitudinal center of each pattern (and head core), e.g., with respect to the
longitudinal center of a shank portion 312 of each pattern.
[0041] Because the insertion and removal of the lock guide insert piece
304 and the thrower lug insert piece 308 is semi-automated, insertion
thereof is guided to the correct location for each cycle of molding, and is
easily removed manually before the next cycle. This fact and that the insert
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pieces 304 and 308 remain on the mold boxes 300 and 310 saves time,
making the molding process faster for each core.
[0042] Furthermore, the lock guide insert piece 304 and the thrower
lug
insert piece 308 are designed with precision so that they fit tightly in the
main core box slots 302 and 306, respectively. The tight fit, i.e. within
about
a 0.005 inch tolerance of the slot dimensions, is to prevent sand from
blowing out through any space between the main core box slots and the
tooling insert pieces themselves when sand is blown into the main core
boxes 300 and 310 to form the main body core 100 or 200. After the main
body core has been formed from the blown sand and the sand has set, it is
preferred to pull out both insert pieces 304 and 308 to create accurate
cavities or apertures for the lock guide lug 340 and the thrower lug 350,
respectively. For instance, if these insert pieces could not be pulled out of
the core box, it would be not be possible to remove the core from the main
core box 310 as shown in Figure 4B. A secondary operation to form the lock
guide lug and thrower lug cavities in the core would have to be used.
Accordingly, the shape and angles of the insert pieces 304 and 308 were
selected carefully to release from the sand, leaving only the properly-shaped
cavity in the body core 100 or 200.
[0043] Figure 4C displays the first mold box 300 defining the first pattern
301 with a first plug 314 inserted into the shank portion 312 of the pattern
301. The first plug 314 includes a recess 315 to help form a connector (403
in Figures 7 and 8A). The recess 315 may further define a notched or
angled surface 317 (or "notch") to make the connector 403 asymmetrical
(Figure 8A). The other side of the plug 314 is displayed in Figure 5A.
[0044] Figure 4D displays the second pattern 311 with a second plug
324
inserted into the shank portion 312 of the pattern. The second plug 324 may
include a corresponding recess 315 to form the other half of the connector
403. The other side of the plug 324 is shown in Figure 5B. Alternatively, the
plugs 314 and 324 may be combined into a single plug (not shown). The
plugs 314 and 324 (or plug in the case of a single plug) close off the shank
core 312 portions of the patterns of the mold box. The result is truncation of
the shank core from the head core to form a Type-E head core 200 (Figure
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7) adapted for use with a Type-F shank core used to form the railroad
coupler 254 shown in Figure 3B.
[0045] With further reference to Figures 8A through 8D, the adapted
head
core 200 includes a male connector 403 formed by the plugs 314 and 324.
The male connector 403 is insertable into a female connector 413 of the
shank core 204 (Figure 9A) corresponding to the shape of the male
connector 403, to create a connection joint 533 (Figures 9B and 9C). As
will be further explained, the connection joint 533 may be a precise, tight-
fitting joint that substantially prevents shifting, and removes the concern
that
lo a T-section would form internal to the shank, which could result in hot
tears
at the bottom of the horn-to-shank interface.
[0046] The shank core 204 may be any of a variety of shank cores of
different lengths or types, adapted with the female connector 413. The
shape of the connectors 403 and 413 may be rectangular, square, oblong,
tapered or any other viable shape or configuration. In an alternative
embodiment, a connector formed on the adapted head core 200 may be
some other type of connector, including but not limited to a female connector
identical or similar to the female connector 413 shown on the shank core
204 in Figures 8B and 8D. Likewise, the shank core 204 may include a
corresponding male connector identical or similar to the male connector 403
shown in Figures 7 and 8A.
[0047] As discussed, the recess 315 on the plug 314 may be used to
create a notch 405 on one side of the male connector 403. The shank core
may include an end having a raised portion 415 corresponding to the notch
405 of the adapted head core, creating a tight-fitting connection joint 533
that is resistant to shifting and/or misalignment when connecting the male
connector 403 to the female connector 413 of the shank core. The
connection joint 533 may also be structured and tapered to aid in preventing
shifting and/or misalignment. The dimensions displayed in Figures 8C and
8D may vary, but in one example: height Y1 of the male connector 403 may
be about 3 inches; height Y2 of the male connector 403 with a height of the
notch 405 subtracted may be about 2 inches; height Y3 of the notch 403
may be about 0.6 inches; length X1 of the male connector 403 may be about
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3 inches; length X2 of the notch 405 may be about 1.5 inches; width X3 of
the female connector 413 may be about 3.2 inches; and radius R1 radius of
the curved notch 405 may be about 0.7 inches. These dimensions may vary
between at least 0.2 to 0.6 inches.
5 [0048] The connection joint 533 shown in Figure 9C may be located
within an optimum window of distance from a front face 543 of the head core
200 defined by dimensions X1 and X2. X1 may be a minimum dimension to
a first end 545 of the connection joint 533 closest to the front face 543 and
X2 may be a maximum dimension to a second end 547 of the connection
lo joint 533 farthest from the front face 543. X1 may be between about 14
and
17 inches while X2 may be between about 18 and 20 inches. A mid-point of
the connection joint 533 may therefore be located between about 16 and 18
inches from the front face of the head core 200.
[0049] The main body (or head) cores 100 and 200 and various shank
cores 204 may be formed from a relatively low-cost molding material, such
as no-bake or air-set sand, which may have a grain fineness number (GFN)
in the range of 44-55 GFN. The molding material may be new sand or
reclaimed sand. That is, sand that has been previously used to make
castings. The reclaimed sand may be obtained by subjecting used molds to
various shaking, thermal, and/or crushing operations that break down the
mold into finer and finer constituent sizes until a desired grain size is
obtained. Screening operations facilitate separation of the sand by size.
Finally, the sand is subjected to high temperatures to burn off any residual
coating or other impurities, such as the binder material. The reclaimed sand
is then mixed with new binder at a ratio of about 99:1 and placed into a mold
and allowed to set. Once set, the new mold, in this case the main body,
head or shank core, is ready to be used within the cope and drag mold
portions for casting the coupler body.
[0050] The more-refined sand may be reserved for just those portions
of
the mold that require improved surface finish and/or greater dimensional
accuracy, such as the internal cavities, gating system, small core features
and the like. Use of a no-bake or cold box process (also referred to as a
cold shell sand process) may also prevent hot tears that can result when
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using other common processes (such as green sand molding). The no-bake
or cold box process also improves dimensional accuracy and surface finish
as further described in U.S. Application No. 12/685,346, entitled "Use of No-
Bake Mold Process to Manufacture Railroad Couplers" and filed January 11,
2010, which is incorporated by this reference herein in its entirety.
[0051] Figure 12 is a flow chart of a method for creating a main body
core
for casting a coupler body of a railcar coupler. At block 1200, the method
includes inserting a plug into a pattern of a main body core box, the plug
configured to adapt an end of the pattern of the main body core box so that a
lo head core formed within the pattern includes a first half of a
connection joint
attachable to a second shank core, the second shank core different than a
first shank core formed integral with the head core when the plug is not
used. At block 1210, the method includes blowing sand into the main body
core box. At block 1220, the method includes curing the sand to form a
head core including the first half of the connection joint. At block 1230, the
method includes attaching the first half of the connection joint to a
corresponding second half of the connection joint of the second shank core.
[0052] The terms and descriptions used herein are set forth by way of
illustration only and are not meant as limitations. Those skilled in the art
will
recognize that many variations can be made to the details of the above-
described embodiments without departing from the underlying principles of
the disclosed embodiments. For example, the steps of the methods need
not be executed in a certain order, unless specified, although they may have
been presented in that order in the disclosure. The scope of the invention
should, therefore, be determined only by the following claims (and their
equivalents) in which all terms are to be understood in their broadest
reasonable sense unless otherwise indicated.
