Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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METHOD OF DIE CAST~NG A
REDUCIBLE CORE
FIELD OF THE INVENTION
The invention generally relates to the
manufacture of reducible cores used in the manufacture
of machine parts. The invention also generally
relates to the manufacture of cylinder blocks using
reducible cores to form the intecior cylinder
bores and passages associated therewith.
DESCRIPTION OF THE PRIOR ART
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Cores are used to form interior passages or
cavities in cast machine parts. Such cores can be
formed of a reducible material, such as sand or salt,
which is molded into a configuration conforming to
the desired shape of the interior cavity or passage.
The core maintains this configuration while the part
is being cast around it, and is thereafter reduced or
removed to open the passage or cavity in the part.
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Attention is directed to Canadian
Patent 1,167,716, issued May 22, 1984 and
entitled "CYLINDER BLOCK HAVING A
CAST IN CORE UNIT AND PROCESS OF .~ANUFACTURING
SAME".
Attention is also directed to the following
United Staces Patents:
Leach 2,858,587 Nov. 4, 1958
Hrabovsky 2,978,764 April 11, 1961
Seyffer et al 3,149,383 Sept. 22, 1964
Chramm et al 4,003,422 Jan. 18, 1977
Hayashi et al 4,077,458 Mar. 7, 1978
Edwards 4,102~733 Aug. 1, 1978
SUMMARY OF THE INYENTION
The invention provides a method of die casting
a core comprising the steps of fabricating a die
defining a cavity in which the core is formed, and
injec~ing under pressure a reducible material in a
molten state into the cavity of the die, thereby
die casting the core.
In one embodiment, the method includes the
additional steps of fabricating a preformed liner
having a bore and placing the liner in the cavity
of the die. In this embodiment~ the step of
injecting the molten reducible material comprises
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injecting under pressure the molten reducible
material into the bore of the liner, thereby
providing the liner with a reducible die-cast
core.
In one embodiment, the step of fabricating
the die comprises fabricating a die defining a main
cavity in which a main body portion of the core is
formed and an auxiliary cavity which communicates
with the main cavity and in which an auxiliary body
portion of t`he core is formed. In this embodiment,
che step of injecting the molten reducible material
comprises injecting under pressure a reducible
material in a molten state into the main and
auxiliary cavities of the die, thereby die-casting
the core having a main body portion and an auxiliary
body portion communicating with the main body
portion.
In one embodiment, the preformed cylinder
liner is placed in the main cavity of the die. In
this embodiment, the step of injecting the molten
material comprises injecting under pressure the
molten reducible material into the bore of the
liner and the auxiliary cavity of the die, thereby
providing the liner with a reducible die cast core
having an auxiliary body portion extending outwardly
o~ the liner.
The invention also provides a method of
fabricating a cylinder block comprising the steps
of die casting a core following the method as above
described and then placing the die-cast core into a
cylinder block mold. ~olten metal is caused to
enter the cylinder block mold, thereby forming a
cylinder block surrounding the die-cast core. The
reducible material is then removed to provide a
cavity in the cylinder block conforming to the
shape of the die-cast core. In the preferred
embodiment, the cavity defines the cylinder bore
and exhaust and transfer passages communicating
with the bore.
One of the principal features of the
invention is the provision of a die-cast core which
is uniformly dense and dimensionally stable and
which is capable of being formed into intricate
configurations.
Other features and advantages of the
embodiments of the invention will become apparent
upon reviewing the fo]lowing general description,
the drawings, and the appended claims.
DESCRIPTION OF THE D~AWINGS
Fig. l is a sectional diagrammatic view oE
a cylinder block cast around a die-cast core which
embodies various of the features of the invention;
Fig. 2 is a perspective view, partially
broken away, of a die in which the die-cast core
used to cast the cylinder block in Fig. 1 can be
formed;
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Fig. 3 is an exploded perspective view of
the die shown in Fig. 2 and showing one embodiment
of the core which can be formed therein;
Fig. 4 is the die-cast core shown Fig. 3 in
position in a cylinder block mold;
Fig. 5 is a perspective view9 partially
broken away, of the die similar to Fig. 2, except
that a preformed cylinder liner is located in the
cavity of the die;
Fig. 6 is a preformed cylinder liner and
die-cast core unit which is formed in the die shown
in Fig. 5; and
Fig. 7 is the preformed cylinder liner and
die-cast core unit shown in Fig. 6 in position in a
cylinder block mold.
Before explaining the embodiments of the
invention in detail, it is to be understood that
the invention is not limited in its application to
the details of the construct:ion and the arrangements
of the components set forth in the following
description or as illustrated in the drawings. The
invention is capable of other embodiments and of
being practiced or carried out in various ways.
Also, it is to be understood that the phraseology
and terminology employed herein is for purpose of
description and should not be recorded as limiting.
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GENERAL DESCRIPTION
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Machine parts are typically manufactured by
casting in permanent molds or in high pressure
die casting machines. By design, such machine
parts often include integrally cast open interior
areas or cavities. To form these open interior
areas during casting, a preEormed core of a reducible
material, such as salt or sand, can be utilized.
In the illustrated embodiment, in order to
manufacture a reducible core which is uniformly
dense, dimensionally stable, and capable of main-
taining intricate configurations during casting, a
core 10 is fabricated by die casting.
While a die-cast core is applicable for use
whenever it is desired to fabricate cored machine
parts, for the purpose of description, the core 10
of the illustrated embodiment is fabricated for
particular use in the production of cylinder bores
for internal combustion engines.
In this environment (see Fig. 1), a cylinder
block 12 ir,cludes integrally cast open interior
areas and passages. As illustrated, such areas
take the form of a cylinder bore 14 as well as a
transfer passage 16 and an exhaust passage 18
communicating with the bore 14. Typically more
than a single transfer passage 16 is provided,
however only one such transfer passage 16 is
illustrated in the drawings. A cylinder liner 36
is located in the bore 14. The liner 36 has
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openings 38 or ports which provide the desired
communication between the bore 14 and the transfer
and exhaust passages 16 and 18.
In order to manufacture the core 10 used in
the production oE the above described cylinder
block 12 (see Figs. 2 and 3), a die 22 is fabricated.
As is shown in Fig. 3, the die 22 includes two
separable members 22a and 22b. When the members
are assembled (see Fig. 2), the die 22 defines a
cavity 24 in which the core 10 can be formed. In
the illustrated construction, the cavity 24 includes
a main portion 26 and two auxiliary portions 28a
and 28b which communicate with the main portion
26.
Molten reducible material is placed in the
die 22 through a top opening in the die 22 and is
then injected under pressure, such as by the use of
a ram 23, into the main and auxiliary cavity
portions 26, 28a and 28b of the die 22, thereby
forming the die-cast core 10. The die members are
then separated taS shown in Fig. 3) to remove the
die cast core 10.
~ s shown in Fig. 3, the resulting die-cast
core 10 includes a main body portion 30 which was
formed in the main cavity portion 26 of the die 22
and3 which forms the core for the cylinder bore 14
shown in Fig. 1. The core 10 also includes au~iliary
body portions 32a and 32b which were formed,
respectively, in the auxiliary cavity portions 28a
and 28b of the die 22 and which form, respectively,
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the cores for the transfer and exhaust passages 16
and 18 which communicate with the bore 14.
To use the core 10 to manufacture the
cylinder block 12 shown in Fig. 1, the core 10 is
placed into a cylinder block mold 34 (shown in Fig.
4), and molten metal is caused to enter the cylinder
block mold 34. Alternatively, the core 10 could be
placed in a high pressure die casting machine in
which the block 12 is cast. In either case, the
block 12 is formed surrounding the reducible core
10 .
The reducible material of the core 10 is
then removed by breaking or crushing and/or by
flushing the material out by water to open the
cylinder bore 14 and associated transEer and
exhaust passages 16 and 18.
The liner 36 can then be pressed into the
open cylinder bore 14, with the liner openings 38
properly aligned with the transfer and exhaust
passages 16 and 18. The desired communication
between the bore 14 and these passages 16 and 18 i5
thus provided.
An alternate construction of the core 10 is
shown in Figs. 5 and 6. Structural components in
this embodiment which are shared with the previously
discussed embodiment are given common reference
numerals.
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In this construction, and like the construc-
tion shown in Figs. 2 and 3, the separable two-piece
die 22 includes the main cavity portion 26 and
auxiliary cavity portions 28a and 28b whicn commu-
nicate with the main cavity portion 26.
However, in this embodiment and unlike theemodiment shown in Figs. 2 and 3, the liner 36 is
itself placed in the main cavity portion 26 of
the die 22 (see Fig. 5) be~ore the die-cast core 10
is formed. The liner 36 is positioned in the main
cavity portion 26 so that its openings 38 are
properly aligned with the auxiliary cavity portions
28a and 28b of the die 22.
Molten reducible material is then injected
under pressure by the ram 23 into the main cavity
portion 26 and the auxiliary cavity portions 28a
and 28b of the die 22. The preformed liner 36 is
thus provided with the integral reducible die-cast
core 10 (as is shown in Fig. 6) which includes the
main bod~ portion 30 forming the core for the liner
bore and auxiliary body portions 32a and 32b
extending outwardly from the liner 36 and forming
the cores of the transfer and exhaust passages 16
and 18 which communicate with the liner bore.
To use the core 10 as shown in Fig. 6 to
manufacture the cylinder block 12 as shown in Fig.
1, the preformed liner 36 and its die-cast core 10
is placed in the cylinder block mold 3~ or in the
high-pressure die casting machine (see Fig. 7).
Molten metal is then caused to enter the cylinder
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block mold 34 to form a cylinder block 12 surround-
ing the liner 36 and its die-cast core 10. The
reducible material is removed as above described
and a cylinder block 12 having a cast-in cylinder
liner 20 and integrally cast transfer and exhaust
passages 16 and 18 is thereby formed.
In the preferred embodiment, the reducible
material is salt, such as sodium chloride or
potassium chloride. Alternatively, a salt mixture
of two or more salts can be utilized. The salt is
heated to a temperature sufficiently above its
melting point to permit liquid flow. Typical melting
temperatures are 1200 F or less for salt mixtures,
and 1~74 F for sodium chloride. The mol-ten salt
is injected into the die at a pressure consistent
with the minimum required to prevent excessive
porosity and shrink of the core, and within ~he
maximum allowable by the die cmd injection machine.
Typical pre,ssures used might be 3000 to 10,000
pounds per square inch,
Various of the ~eatures of the invention
are set ~orth in the following claims.
