Note: Descriptions are shown in the official language in which they were submitted.
~ t~7~
--1 ~
I~escription
Sand Core P_ttern and Method
of Forminq a Sand Mold
Technical Field
This invention relates to a pattern and method
for forming a sand mold for a one-piece annular casting
having a plurality of angled blades extending between
radially inner and outer rings.
Backqround Art
Annular blade fluid flow deflectors such as
the stator of a torque converter, a compressor wheel
for a turbine, etc. are difficult to manufacture as a
unitized assembly. In forming such flow deflectors, a
number of different manufacturing techniques have been
employed. In one such prior manufacturing technique,
the individual blades of the stator were machined in
segments and subsequently secured together to form the
complete stator structure.
In another prior manufacturing method, the
blade patterns were pegged into a shell ring prior to
forming the sand mold thereabout. A problem arose in
such manufacture in that variations in spacing and
profile occurred in the patterns so that the stator was
not completely uniform for providing a completely
balanced flow of the fluid in the torque converter.
Disclosure of Invention
rrhe present invention provides a pattern for
forming a sand mold for a one-piece annular casting
having radially inner and outer rings and a plurality
of angled blades extending between the rings. The
improved pattern includes a plurality of segments each
-la-
having a first end portion defining a portion of the
profile of one of the rings and a second end portion
~5
1~59~57(~
--2--
defining the profile of one blade, means for supporting
the segments in an annular array to define cumulatively
a pattern structure corresponding to the configuration
of the one ring and blades, and a removable ring
coaxial with the array of segments to define a pattern
structure corresponding to the configuration or profile
of the other one of the rings.
The illustrated embodiment comprehends an
improved sand core pattern for producing a one-piece
cast wheel for use as a fluid flow deflector. The
wheel includes a radially inner annular shell, a
coaxial radially outer annular blade support, and a
plurality of angled blades extending in a spaced
annular array between the shell and blade support to
define the desired fluid flow deflector.
The segments of the illustrated embodiment are
configured to permit radially inward removal thereof
from the array upon removal of the supporting means.
Specifically, the inner end portions of the segments
are alternatively tapered in the array to sequentially
widen inwardly and narrow inwardly. Furthermore, the
side faces of the shell-forming portion of the segments
define intersecting planes.
The removable ring illustratively comprises a
split ring which may be withdrawn radially outwardly
upon completion of the forming of the sand mold. In
the illustrated embodiment, the ring defines a pattern
preselected to permit suitable subsequent machining of
the casting portion defined by the ring pattern to the
final desired outer ring configuration.
The pattern can be arranged so that upon
removal of the support of the segments, every other
segment may be removed by a radially inward movement
thereof as a result of the inwardly widening
configuration of the segment shell portion.
115~S~7~
--3--
The segments of the instant example can be
mounted annularly about a cylindrical mandrel in
effecting the support thereof during the mold-forming
steps. Upon removal of the mandrel at the completion
of the sand mold formation, the segments may be
withdrawn sequentially into the axial space previously
occupied by the mandrel.
The side faces of the adjacent segment shell
portions can resultingly define interlocking means
which, in cooperation with the mandrel and outer
locking ring, provide a positive, fixed retention of
the elements of the pattern during the sand mold
forming step.
Each of the segments may be readily formed by
identical machining operations so as to provide
uniformity in the blade configuration throughout the
array. The shell portion of each of the segments may
be machined to define selectively the inwardly and
outwardly diverging angular configuration discussed
above.
As a result, the cast wheel may comprise a
totally uniform configuration to provide a completely
balanced flow of fluid therethrough. The sand core
pattern and method of forming the sand mold utilizing
the pattern of the invention are extremely simple and
economical while yet providing the highly improved cast
wheel structure.
Brief Description of the Drawing
FIGURE l is a perspective view of a cast wheel
manufactured in accordance with the invention;
FIGURE 2 is a side elevation thereof;
FIGURE 3 is a vertical section taken along the
line 3-3 o~ Figure 2;
~1S457U
-3a
FIGUR~ 4 is a perspective view illustrating
the sand core pattern in partially assembled
relationship for use in forming the sand mold to
produce the wheel of Figure 1.
-` 1154570
FIGURR 5 is a fragmentary radial section il-
lustrating the interlocked relationship of the shell
portions of the segments defining a portion of the
pattern;
FIGURE 6 is a side elevation of a pair of ad-
jacent segments of the annular array thereof illus-
trated in Figure 4, and
FIGURE 7 is a diametric section of the struc-
ture upon completion of the flowing of the sand to
define the sand mold about the pattern illustrated in
Figure 4.
Best Mode for Carrying Out the Invention
In the drawing, an improved method of manufacture
of a stator wheel 10, or the like, is shown to comprise
the formation of a pattern generally designated 11 for
producing the wheel 10 as a one-piece cast wheel.
As shown in Figure 1, the wheel includes a
radially inner annular shell portion 12, a coaxial
radially outer blade support 13, and a plurality of
angled blades 14 extending in a spaced annular array
between the shell and blade support to define a fluid
flow deflector, such as for use in a torque converter
stator structure.
The blades 14 are of complex configuration
and it is desirable to arrange the blades in the array
illustrated in Figure 1 in accurately positioned and
spaced relationship so as to provide a completely bal-
anced and uniform wheel 10. The present invention
permits the individual blades 14 to be de~ined by
identical segments 15 of the pattern 11 which di~fer
only in the angularity of the circumferentially oppo-
site side faces 16 and 17 of an inner end portion 18
- ' '. . ~
. , ,', ~ . ,:. . .
~4S7~?
of the seyments.
As best seen in E'igures 4 and 5, segments 15a
define planar side faces 16a and 17a which converge
radially outwardly from the axis 19 of the segment
array. Segments 15b define planar side faces 16b and
17b which converge radially inwardly in facial abutment
with surfaces 16a and 17a of the adjacent segments
15a. In the illustrated embodiment, the included angle
between faces 16a and 17a and, thus, between faces 16b
and 17b, is approximately 60 . As shown in Figure 5,
faces 16b and 17b intersect in spaced relationship to
axis 19.
Segments 15a, as shown in Figure 6, include a
first inner end portion 20a defined by the planar
15 surfaces 16a and 17a, and segments 16 include a
corresponding first inner end portion defined by
surfaces 16b and 17b. Each of the segments defines a
similar blade portion 21. As shown in Figure 4, the
side surfaces of the inner end portions of the segments
are curvilinear.
In the illustrated embodiment of Figure 5, an
odd number of segments is utilized requiring the
provision of a third form of segment 15c at one
position in the annular array generally designated 22.
~egment 15c includes an inner end portion 18c wherein
the side surfaces 17c and 16c extend at an angle
suitably to engage the counterclockwise side surface of
the adjacent segment 15b and the clockwise side surface
of the adjacent segment 15a.
As can be seen in Figures 4 and 5, the annular
array 22 of the segments defines a complete annulus
wherein the inner portions 18 define an inner
continuous ring and the blades 21 are spaced apart
uniformly at a uniform angle to deEine a fluid flow
deflector pattern 23.
4S7(~
-6-
The annular array 22 is foxmed about a trans-
versely split mandrel 25, which, as illustrated in Fiy-
ure 7, has an outer arcuate configuration corresponding
to the desired inside configuration of the finished
stator wheel. As the segments are being installed,
they are held in place by a lock ring 25a positioned
in a groove 25b located in the inner portion 18 of the
segments 15. After the annular arrangement is com-
pleted, an outer ring 26, which forms a portion of
core box 28, is brought into encircling relationship
to the outer tips 24 of the blades, as shown in Fig-
ure 4. (The mandrel 25 is omitted in Figure 4 to
facilitate showing of the arrangement of the segments.)
Outer ring 26 and core box 28 preferably comprise a
split ring which includes locking means 27 for causing
firm embracing of the blade tips 24 in the annular
array of the segments.
After the pattern is assembled on the man-
drel 25 and with the outer ring 26 installed, as shown
in Figure 7, molding sand 29 may be packed around the
pattern and subsequently cured to form the desired
sand mold M in which the stator wheel 10 is cast.
Sand mold M is then removed from the core
box 28 and mandrel 25 and split ring 26 are removed.
Removal of mandrel 25 from annular array 22 permits
the removal of the segments 15 sequentially from the
annular array. More specifically, upon removal of
mandrel 25, segments 15a may be removed by a radially
inward withdrawal thereof from the annular array as
permitted by the inwardly widening side surface con-
figuration. Upon removal of segments 15a, segments
15b, and segment 15c when used, may then be removed
to complete the removal of the pattern from the sand
mold for subsequent casting of the stator wheel 10 in
the formed mold.
..
llS9~57(~
--7--
As the inner portions 18 of the respective
segments effectively define a continuous annular ring
portion of the pattern, as seen in Figures 4 and 5,
the sand mold correspondingly defines a continuous
ring cavity for defining the shell 12 of the wheel 10,
seen in Figure 1. Further, as each of the segment
blade portions 21 was accurately and positively posi-
tioned in the annular array 22, the resultant cast
blades 14 are similarly accurately spaced and posi-
tioned in the wheel 10.
As illustrated in Figure 3, the configura-
tion of the split ring 26 may not correspond exactly
to the desired final configuration of the blade sup-
port 13. Thus, illustratively, the outer portion of
the casting may comprise a rectangular section ring
which ma~ be suitably machined to the final config-
uration of the blade support 13, as shown in Figure 3.
As further illustrated in Figure 3, the
shell 12 may be further machined at its opposite ends
30 and 31, as desired.
Industrial Applicability
The cast wheel structure provides an improved
uniform, accurately configured complex-shaped structure
which is adapted for use in a wide range of industrial
applications, such as the stator of a torque converter
wherein it is desirable to provide accurate, uniform
blade deflectors at low cost.
As the pattern for the casting mold is made
up of a plurality of readily repeatable machined seg-
ments, high accuracy in the configuration of the pat-
tern and, as a result, the configuration of the cast-
ing made from the mold formed by the pattern, is
obtained.
1~5~5-;~V
As indicated above, the structural and method
concepts are adapted for providing either an even num-
ber of blades or odd number of blades in the cast
wheel as desired. As will be obvious to those skilled
in the art, where an even number of blades is desired,
the segment 15c is omitted and the circumferential ex-
tent of each of the segments l5a and 15b correspond-
ingly increased to form the continuous annular array
defining the shell portion of the wheel.
The invention permits the production of sand
cores for castings in such relatively complex-shaped
castings as wheel 10 by numerical control machining
steps in forming the individual segments. The inter-
locking angle of the side surfaces of the segments
assures that the blade portions thereof are effec-
tively accurately retained while the molding sand is
being packed around the pattern, thereby assuring a
uniform blade arrangement. Where the wheel is util-
ized as a torque converter stator, such uniform stator
configuration provides a highly desirable balanced
flow of fluid through the diverter means.
While the invention is disclosed in connec-
tion with the stator wheel construction of Figure 1,
as will be obvious to those skilled in the art, the
novel segmented pattern concept and pattern forming
process of the invention may be utilized in conjunc-
tion with a wide range of different annular configur-
ations.
Other aspects, objects and advantages of
this invention can be obtained from a study of the
drawings, the disclosure and the appended claims. The
foregoing disclosure of specific embodiments is
illustrative of the broad inventive concepts compre-
hended by the invention.
