PERMANENT CASTING MOLD

MOULE PERMANENT DE COULEE

English Abstract

ABSTRACT OF THE DISCLOSURE
A permanent mold, particularly a metal mold, has a gap
between the shell and a feeder insert for attaching the feeder
insert on to the casting. During the casting process, the
liquid metal penetrates into the gap and hardens promptly. The
thin bushing which is thus formed creates a solid connection
between the casting and the feeder or feeder insert. Thus, the
casting can be removed earlier from the mold.
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Claims

The embodiments of the invention in which an exclusive
property or privilege is claimed are defined as follows:
1. In a permanent mold, especially a metal shell mold, of the
type having an inner chamber and at least one opening to receive
a feeder insert for delivery of casting material to said inner
chamber, the improvement wherein
said shell and said insert include means defining an open space
communicating with said inner chamber for receiving molten
casting material.
2. A mold according to Claim 1, wherein said means defining
said space comprises a recess formed in a wall of said shell
surrounding said feeder insert along its periphery adjacent said
inner chamber.
3. A mold according to Claim 2, wherein said recess in said
shell wall extends continuously along its periphery.
4. A mold according to Claim 3, wherein said recess in said
shell wall extends intermittently along its periphery.
5. A mold according to Claim 1, wherein said mold includes a
plurality of grooves interconnecting said recess with the
interior of said feeder.
6. A mold according to Claim 1, wherein said recess is formed
by at least one cutout in said feeder insert.
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7. A mold according to any of Claim 1 , wherein the depth
of said recess is a function of the flow capacity of the
material being cast and lies between about 0.5 and about 10 mm.
8. A mold according to Claim 7, wherein the depth of said
recess is between about 0.5 and about 5 mm.
9. A method of unitarily interconnecting a casting and a feeder
insert comprising
providing a permanent metal shell mold having an interior
chamber and an opening in one wall to receive a feeder insert
such that the insert and the wall portion around the opening
define a space which is a continuation of the interior chamber
and which substantially surrounds the insert;
feeding molten metal through the feeder insert into the interior
chamber to form the casting and continuing to feed material
until the space around the insert is filled,
permitting the casting to cool by heat conduction through the
metal shell until at least the material in the space and the
adjacent portion of the casting is hard, thereby forming a rigid
connection between the casting and the insert, and
removing the casting from the mold.
10. A method according to Claim 9 wherein the feeder modulus is
selected to promote proper filling of the mold in accordance
with the relationship
8.

Mcasting = <IMG> ,
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Description

20943
PERMANENT CASTING MOLD
68
Ivo Henych
Erwin Fischer
Eduard Rogg
~ SPECIFICATION
This invention relates to an improved permanent metal
shel.l mold and to a method of connecting a feeder insert to a
casting formed in such a mold~
Background O The Invention
The proper, rapid and tight feeding of the molten
material in the casting of metals and alloys when thexe is a
volume deficit, i.e. shrinkage, during the hardening rnust be
guaranteed by the feeder. The mate.rial in the feeder must
harden last, that is to say, not until after the hardening of
tha casting, to guarantee proper feeding so that filling of the
mold occurs in the proper order. Because of this, so called
sink head, lost head, or dead head feeders are used with steel
work molds, or with steel casting and the like.
With casting in the metal molds, especially gravity
die casting, cover plates which include feeder inserts can be
used as disclosed in German patent 26 22 891. These cover

68
plates are formed during the casting of the top part of the
shell. After completion of the casting process, but still
before the casting is completely hardened, these cover plates
are removed from the shell with the casting. The shell is freed
or the next casting process before the hardening of the entire
casting.
The disclosed methods have disadvantageous aspects.
Either tney lengthen the occupied time of the shell or certain
difficulties arise with the removal of the casting, e.g.,
flowing out of the liquid content remaining in the feeder by the
dislocation of the cover plates.
Also, the known methods and devices are inefficient
particularly in connection with the manufacture of small
castings.
Brief Description Of The Inventlon
An object of the present invention is to provide a
permanent mold in which the feeder inserts are connected with
the cast such that the advantages of the aforementioned cover
plate technique are preserved without its disadvantages.
Thus, the improved structure and method in accordance
with the invention permits:
(a) removal of the casting from the shell mold before
complete hardening of the material within the feeder;
~b) simplification of the unpacking without the
danger that the liquid content of the feeder will flow out;
tc) coordinating the casting speed with the hardening
such that the feeder size is minimized; and
~d) determining the relationships between the
hardening of the feeder content and the hardening of the casting
so that almost simultaneous hardening occurs whereupon the
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6~3
unpacking from the shell is facilitated by simple expulsion of
- the casting, even with large castings.
~ riefly described, the invention includes in a
permanent mold, especially a me~al shell mold, of the type
having an inner chamber and at least one opening to receive a
feeder insert for delivery of casting material to said inner
chamber, the improvement wherein said shell and said insert
include means defining an open space communicating with said
inner chamber for receiving molten casting material.
In another aspect, the invention includes a method of
unitarily interconnecting a casting and a feeder insert
comprising providing a permanent me-tal shell mold having an
interior chamber and an opening in one wall to receive a feeder
insert such that the insert and the wall portion around the
opening define a space which is a continuation of the interior
chamber and which substantially surrounds the insert; feeding
molten metal though the feeder insert into the interior chamber
to form the casting and continuing to feed material until the
space around the insert is filled, permitting the casting to
coo~ by heat conduction through the metal shell until at least
the meterial in the space and the adjacent portion of the
casting is hard, thereby forming a rigid connection between the
casting and the insert, and removing the casting from the mold.
In order that the manner in which the foregoing and
other objects are attained in accordance with the invention can
be understood in detail, a particularly advantageous embodiment
thereof will be described with reference to the acccmpanying
Jdrawing, which forms a part of this speci~ication, and which
shows a partial side elevation, in section, of the portion of a
casting mold which includes the wall having an opaning to
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.

receive a feeder for delivering molten metal to the interior
chamber of the mold.
As illustrated in the drawing, a permanent metal shell
mold 1 has an opening la in an upper wall which receives a
feeder insert 2. Between feeder insert 2 and the interior
chamber 5 of the shell mold is a breaking core ~ an open space 3
is provided between feeder insert 2 and the surrounding portion
of the shell wall 1 which defines the opening la in the shell
wall. This hollow space 3 is open to the inner chamber 5 of the
mold and forms a continuation of that chamber so as to be able
to receive liquid metal penetrating from inner chamber 5.
Hollow portions in the shell top or groove-like passages between
the breaking core and the feeder insert, or in the breaking
core, serve for filling chamber 3 with the liquid metal. As
illustrated, chamber 3 is generally annular and can be either
continuous or can be interrupted by radially extending portions
of the Eeeder insert or o the shell 1.
A condition necessary for the unpacking of the casting
before the hardening of the feeder is that the feeder must have
a solid connection with the casting. This is accomplished in
accordance with the present invention by means of the controlled
formation oE a leaf, i.e., a thin bushing, which is formed Erom
the cast material around the feeder insert as an extension of
the casting itselE. The required size of the annular space 3 is
determined by the flow capacity of the cast material and can be
between abou~ 0.5 and about 10 mm in thickness, but preferably
between 0~5 and about 5 mm. Another criterion is the simple
removability of the bushing without the danger of breaking the
casting by hammering portions of it off simultaneously with the
~eeder. In accordance with the present invention, the eeder
insert or the bushings surrounding the feeder insert which is of
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cast metal, is tightly connected with the casting and the
inadvertant outflow of liquid material is thereby prevented.
The liquid metal penetrating into the annular space
between the top part of the shell and the feeder insert hardens
as a result of the heat conduction of ~he shell almost
immediately, and the solid connection is formed between the
casting and the feeder insert quicklyO Then, the casting can be
removed from the shell mold without danger.
The adjustment or adaptation of the casting speed to
the heat transmission between the mold and casting occurs such
that the hardening zone of the casting follows approximately in
saturation blanks. The feeder volume can thereby be held to a
minimum.
It can, thus, be arranged that the shrinkage volume
which is to be filled by the liquid feeder content is reduced
and the hardening speed in the feeder and in the casting again
assumes greater importance. To guarantee the feeding in the
proper order, the necessary feeder modulus can be determined in
accordance with the following formula.
M = M
feeder casting
1 + (4 ~ Mcasting)
With precise determination of the hardening times, the
time that the casting must remain in the shell can be
considerably shortened. This facilitates the simplified
unpacking of the casting by ejection rather than by lifting the
casting out of the shell.
While one advantageous embodiment has been chosen to
illustrate the invention, it will be understood by those skilled
in the art that various changes and modifications can be made
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therein with departing from the scope of the invention as
. defined by the appended claimsl