Note: Descriptions are shown in the official language in which they were submitted.
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BACKGROUND OF IHE IN~NTION'
The present invention relates to squeeze casting,
and more particularly to an improved die assembly utilized
in the casting of high melting point alloys.
The squeeze casting of metals has, in recent years,
assumed great industrial potential since it is well known
that the forming of metals in this manner eliminates shrinkage
voids and produces a casting having superior grain structure.
These improvements are achieved through the application of
pressure on the molten metal during solidification in a
closed die. The pressure acts to remove voids in the casting
and to eliminate any air gap bet~Yeen the casting and the die
so as to increase the rate of heat transfer from the casting
through the die, t.hus producing a very fine grain size.
Heretofore, commercial application of the squeeze
casting process has been generally limited to non-ferrous,
loh~ melting point alloys such as aluminum or zinc. This
limitation in the commercial use of squeeze casting has been
largely due to ~he inability of the prior art ~o provide a
die construction capable of casting metals having melting
points in excess-of 2000F, without having to resort to
costly high temperature resistant materials and/or frequent
replacement of the die.
SU~URY OF T~E INVENTION
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The present invention provides a die assembly con-
struction which simplifîes the fabrication of component
parts, extends their use life, and improves the squeeze
casting operation.
Accordingly, the die assembly is comprised of
upright support means formed with flat-surfaced recesses,
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and includes a lower die defined by end, bottom and side members
which are formed with :Elat surfaces that abut the recess sur-
faces. The members include flat surfaces located opposite the
abutting surfaces and defining a lower die cavity hav.ing its
upper end open to receive molten metal for casting. Preferably
the lower die incl.udes supports for the end members, the latter
being spaced from ad~acent ends of the bottom members to allow
the bottom member to therma~ expand longitudinally without
restriction. A guide member is preferably disposed above the
lower die and has a through-passage communicating with the lower
die cavity and formed with outwardly divergent upper and lower
end sections. Preferably the passage receives an upper die
which applies pressure on the molten metal during solldification,
and has a tapered end cooperating with the outwardly divergent
lower end section to fo.rm a narrow cavity communicating with
the lower die cavity, so that molten metal forced into the narrow
cavity solidifies rapidly thus forming a seal.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a sectional elevation of the die assembly
taken along line 1-1 of Figure 2;
Figure 2 is a sectional elevation of the die assembly
taken along line 2-2 of Figure l;
Figure 3 is a detail sectional view o the lower die
showing the upper die in the inserted position;
Figure 4 is a detail sectional view of the lower die
showing the scored bottom and sides of a worn die cavity;
Figure 5 is a detail sectional view of the lower die
showing the resurfaced and shimmed bottom and sides of a repaired
die cavity;
30Figure ~ is a detail sectional view showing a scored
end of a worn die cavity;
Figure 7 is a detaii sectional view showing the re-
surfaced and shimmed end of a repaired die cavity; and
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Figure 8 is a plan ~iew of the lo~er die ~aken along
line 8-8 of Figure 2.
DESCRIPTION OE I~ PREFERRED`E~ODIME~
_ _
Referring to the igures in the dra~ring, there is
sho~n an upright die assembly 10 which, as indicated at
Figure 1, is divided along a vertical center plane 12 into
a pair of opposed split half sections 14 and 14A that are
horizontally movable to~ard and a~a)~ from each other and are.
comprised of separable and substantially identical component
parts. The sections 14 and 14A are held tightly together by
hydraulically operated pistons, not sho~n, to prevent the
leakage of molten metal be~een sections during the squeeze
casting operation.
Each of the sections 14 and 14A includes a die
block 16 formed with a flat surfaced recess 18 which admits
a lowe~ holding block 20, the latter being, in turn, formed
with a flat-surfaced recess 22 which admits the lower die 24.
An upper holding block 26 is positioned above the lower block
20 and includes a shoulder 27 overlapping on the die block
16. The die 24 is comprised of end, bottom and side members
28~ 30 and 32, end members supports 34, and a guide member
36 having a passage 37 extending there~hrough. ~he guide
member 36 rests on the end and side members Z8 and 32, and
is formed with a tongue and groove 38 and 40 which interlocks
with a complementary tongue and groove 42 and 44 of the
upper holding block 26. The die block 16, and the upper and
lower holding blocks 26 and 20 are formed with axial]y
aligned openings 46A, 46B and 46C which receive the bolts
48 that are threade~ into the opening 46B to dra~ together
and securely fasten the lo~er die 24, the upper and lo~er
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holding blocks 26 and 20, and the die block 16 into a unitary
structure. The die assembly 10 is provided with cooling
passages 50 and heating yassages 51 extending throu h the
die block 16 and the lower holding block 20, respectively.
Figure 1 shows an ul~per die holder 52, and Figures 1 and 2
show an upper die 54 in i~s elevated or retracted position,
and having a tapered end 55. The lower die 24 defines a
cavity 56 of rectilinear configuration. At Fig~res 1, 2, 3,
and 8, the cavity 56 is shown filled ~ith molten metal 58
preparatory to the squeeze casting operation.
Referring specifically to Figure 2, and in accor-
dance with the invention, the lower die 24 is constructed
so that a space 57 is provided between adjacent end surfaces
of tile bottom member 30 and the end member supports 34 and a
space 59 between adjacent surfaces of the side members 32 and the
die block 16. The spaces 57 and 59 are sized to accommodate
the maxi~un longitudinal thermal growth experienced by the
bottom and side members 30 and 32 during the squee7e casting
operation, thereby minimizing distortion of the lower die 24.
Referring specifically ~o Figure 3, there is shown
the upper die 54 in its downward or inserted position, and,
in accordance with the invention, the guide member 36 is
formed with the passage 37 having outwardly divergent upper
and lower end sections 60 ~nd 62 and a straight intermediate
section 64, the latter being sized to slidably engage the
upper die 54 to main~ain its alignment during insertion in~o
the passage 37. The divergent configuration of the end sec~ion
60 facilitates entry of the upper die 54 and minimizes wear
by pTecluding contact be~een the entering upper die 54 -:_
and the end section 60. l~len the upper die 54 is in its
inserted ~osition, the divergent configuration of the end
section 62 cooperates with the upper die tapered end 55
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to form a relatively narrow cavity 66 therebetween. rne molten
metal being forced into the cavity 66, as pressure is applied
through the upper die 54, solidifies rapidl)~, thus forming a
seal to prevent molt~n ]netal spit-out rom the die cavity
56 during the squeeze casting operation.
In accordance with the invention, the end, bottom and
side members 28, 30 and 32 of the l~er die 24 are of rectilinear
configuration and have flat surfaces throughout, thereby provi-
ding a construction which greatly simplifies the fabrication of
the die members~ while also extending their use life as herein-
after described with particular references to Figures 4, 5, 6
and 7.
Referring specifically to Figures 4 and 6, there is
shown a worn die cavity 56 wherein the exposed surfaces of the
end, bottom and side members 28, 30 and 32 are badly scored
due to softening, erosion, heat checki.ng, welding and deforma-
tion while, as shcwn at ~igure 4, ~he upper edges of the bottom
member sides abutting along the center plane lZ are p~rted due
to deformation and erosion.
Referring specifically to Figures ~ and 7, there is
shown the die cavity 56 after it has been repaired without re-
quiring replacement of the damaged end, bottom and side members
28, 30 and 32. In accordance with the invention, the lower die
memb~s ~8, 30 and 32 are separable rom each other, and are
easily taken out of the die assembly 10 by parting the assembly
along the center plane 12, and disengaging the bolts 48 between
the upper and lower holding blocks 26 and 20, shown at Figure 1,
and removing the upper holding block 26 and the guide member 36
from the die assembly 10. The rectilinear configuration and the
flat surfaces of the lo~er die members 28~ 30 and 32 makes them
readily adaptable to simplified ma~Lning procedllres such as
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the flat surace ~rinding of the scored surfaces. The repaired
members 28, 30 and 32 are reinstalled in the die assembly 10
and shinL~ are inserted between the repaired die members and the
abuttin~ support surfaces to make up for the loss of metal re-
moved by tile grinding operation. Accordingly, as sho~n at Figure
7, a sh.im 68A is inserted between the end member 28 and the die
block 16, and, as shown at Figure 5, shims 68B are inserted be-
tween the side members 32 and the lower holding block 20, and
shims 68C and 68D are inserted between the lower holding block
20 and the underside and sides-of the bottom members 30, re-
spectively. The thickness of the shims 68A-B-C equals the metal
loss due to the grinding of scored surfaces of the end, bottom
and side members 28, 30 and 32, respectively. The thickness of
the shim 68D equals the metal loss due to the grinding of the
bottom member sides abutting along the center plane 12. so as to
prouide new upper edges. This repair procedure can be used
repeatedly on the same die until it no longer becomes practical
or until the shims start to fill an area con~acting the molten
metal.
Referring specifically to Figure 8, there are sho~
the end, bottom and side members 28, 30 and 32 forming the die
cavity 56. The exposed surfaces 70 of the end members 28 are
sloped ou'.wardly from the cavity 56 in the direction of the center
plane.l2, thereby facilitating remoYal of the casting.
While .in accordance with the provisions of the statutes
~here is illustrated and described herein a specific embodiment of
the invention, those skillea in the art will understand that
changes may be made in the form of the invention covered by ~he
claims and that certain features of the invention may sometimes
30 be used to advantage without a corresponding use of ~he other
features.
