Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
KDW~092789~5539E 2 @~
MECHANISM AND METHOD FOR MOLDING A HOLLOW P~RT
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to die casting or molding
apparatus and methods, and, more particularly, to methods and
apparatus for molding foam patterns which have ther~in a cavity
which are usable in a lost foam casting process. The in~ention
also relates to a method for separating molded patterns having
therein a cavity from a pair of mold dies.
Reference to Prior Art
Conventional injection molding or die casting
apparatus includes mold pieces or die members having therein
surfaces at least partially defining a mold cavity. If the
molded part i6 to contain a cavity or void, or is to be hollow,
the apparatus can also include a core, with the core having an
outer surface at least partially defining the cavity or void
within the molded part.
Conventional injection molding or die casting
processes begin by locating mold pieces or die members adjacent
to one another to form a mold cavity. Foam or other material
is then injected into the cavity formed by the die members and
the core. The foam or other material is allowed to cure to
form the molded part. Removal of the molded part from the
molding apparatus is accomplished by separating the mold dies a
distance sufficient to disengage the surface of at least one
mold die from the outer surface of the molded part, and
separating the molded part from the remaining die member by
using an ejector mechanism.
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Attention is directed to U.S. Patent 3,632,259,
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Stanciu, which was granted on January 4, 1972, and to U.S.
~c~ Patent 4,632,169, Osborn et al., which was granted on
3 ~ December 30, 1986. Attention is also directed to U.S. Patent
Application Serial No. 202,489, VanRens, filed June 3, 1988,
and to U.S. Patent Application Serial No. 202,876, VanRens,
filed June 3, 1988.
SUMMARY OF THE INVENTION
The invention provides a mechanism for molding a part
having therein a cavity comprising a frame, a pair of mold dies
on the frame which are moveable relative to each other in a
first direction and including surfaces at least partially
defining a mold cavity, and a core on the frame, forming the
cavity in the molded part, and being moveable relative to the
mold dies in the first direction and also being moveable
relative to the mold dies in a second direction transverse to
the first direction.
In one embodiment, the mechanism also includes
e~ection means for separating the molded part from one of the
mold dies.
In one embodiment, the mechanism has a mold die which
is fixed to the frame.
The invention also provides a method for separating a
molded part from a pair of mold dies, the molded part having
therein a cavity which is defined by an inner surface, and
which is formed by a core. The molded part also has an outer
surface defined by the pair of mold dies, the mold dies being
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relatively moveable, and having surfaces at least partially
defining a mold cavity. The method comprises the steps of
displacing the core in a first direction by an amount
sufficient to disengage the core from the inner surface of the
molded part and less than the length of the core in the
aforementioned direction, and displacing the core relative to
the mold dies in a second direction transverse to the first
direction by a distance suf~icient to separate the surfaces of
the mold dies from the outer surface of the molded part.
In one embodiment, the step of displacing the core in
a first direction by an amount sufficient to disengage the core
from the inner surface of the molded part, precedes the step of
displacing the core relative to the mold dies in a second
direction transverse to the first direction.
In one embodiment, the step of displacing the core
relative to the mold dies in a second direction transverse to
the first direction precedes the step of displacing the core in
the first direction, and by an amount sufficient to disengage
the core from the inner surface of the molded part.
A principal feature of the invention is the provision
of a mechanism and a method for molding a part having therein a
cavity. Principal features of the mechanism include mold dies
movable relative to one another in a first direction and a core
movable relative to the mold dies in the first direction and
also in a second direction, transverse to the first direction.
This combination of relative movement reduces the overall size
of the mold by allowing the core to remain at least partially
within the molded part until the part is removed completely
from the mechanism by its own movement relative thereto.
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Other features and advantages of the invention will
become apparent to those skilled in the art upon review of the
following detailed description, claims, and drawings.
DESCRIPTION OY THE_RAWINGS
Fig. 1 is a side elevational view, partly in section,
of a mechanism for molding a part having therein a cavity,
embodying various features of the invention.
Fig. 2 is a view similar to Fig. 1 and showing a first
mold die in a second position and the core in a retracted
position.
Fig. 3 is a view similax to Fig. 2 and showing an
ejector mechanism and the core in a second position relative to
the first mold die.
Before one embodiment of the invention is explained in
detail, it is to be understood that the invention is not
limited in its application to the details of construction and
the arrangement~ of components set forth in the following
description or illustrated in the drawings. The invention is
capable of other embodiments and of being practiced or of being
carried out in various ways. Also, it is to be understood that
the phraseology and terminology used herein is for the purpose
of description and should not be regarded as limiting.
DESCRIPTION OF THE PREFERRED EMBODIMENT
A die casting or molding assembly 4 Pmbodying the
invention is illustrated in the drawinys. While the molding
assembly 4 may be used for moldin~ various parts, in the
preferred embodiment, the molding assembly is used for molding
foam patterns which have therein a cavity and which are used in
a lost foam casting process. As shown in Fig. 1, the molding
assembly 4 includes a molding apparatus 6 mounted on a support
frame 8. The molding apparatus 6 includes first and second
relatively movable mold dies or parts 10 and 12, respectively.
In the preferred embodiment, the first mold die 10 is movably
connected to the frame 8 and the second mold die 12 is rigidly
connected to the frame 8. It should be understood, however,
that both dies 10 and 12 could be movable, or the second die 12
could be movable, and the first mold die 10 could be stationary.
The mold dies 10 and 12 include surfaces 14 and 16,
respectively, each of which partially defines a mold cavity
18. The mold cavity 18 is adapted to be filled with a suitable
material, such as foam beads, for forming a molded part 20,
such as the above-described foam pattern. The mold die
surfaces 14 and 16 each partially define the outer surface 22
of the molded part 20.
The molding apparatus 6 also includes a core 24 which
is supported on the molding apparatus by core support assembly
28. The core support assembly 28 is movably supported on one
end by core support 30, which is connected to mold die 10. The
core support assembly 28 is movably supported on the opposite
end by mold die 10. The core 24 forms the inner surface 32 of
the molded part 20. The inner sùrface 32 of the molded part 20
defines a hollow or cavity 34 in the molded part 20.
While in the illustrated arrangement, the core 24 is
shown as being supported on the molding apparatus 6 by core
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support assembly 2~, in other arrangements the core could be
supported by other parts of the molding apparatus, or by the
frame 8.
The molding apparatus 6 also includes means for
displacing the core 24 relative to the mold dies 10 and 12
between a first or retracted position, (shown in Figs. 2 and 3)
wherein the core 24 is partially extracted from the molded part
20 by an amount sufficient to disengage the core 24 from the
inner surface 32 of the molded part 20, and a second or
extended position, (shown in Fig. 1) wherein the core 24 is
engaged with the inner surface 32 of the molded part 20. While
various suitable means for displacing the core 24 relative to
mold dies 10 and 12 can be employed, in the disclosed
construction, such displacing means comprise an actuator
assembly 36, preferably in the form of a hydraulic or pneumatic
cylinder, supported by the core support asse~bly 28, and
connected to the core 24, to effect reciprocation of the core
24.
While :in the illustrated arrangement, the actuator
assembly 36 i~ supported by the core support assembly 28, in
other arrangements the actuator assembly could be supported by
other parts of the molding apparatus 6, or b~ the frame 8.
The molding apparatus 6 also includes means for
displacing the core 24 relative to the second mold die 12. In
the disclosed construction, the first mold die 10 and connected
core 24 are displaced relative to the second mold die 12
between a ~irst or extended position, wherein the mold dies 10
and 12 are adjacent to one another ~shown in Fig. 1) thereby
forming the mold cavity 18, and a second or retracted position
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wherein the mold dies 10 and 12 are separated and whereby the
outer surface 22 of the molded part 20 is separated from the
surface 16 of the second mold die 12. While various suitable
means can be employed for displacing the core 24 relative to
the second mold die 12, in the disclo&ed construction, such
displacin~ means comprise a hydraulic or pneumatic cylinder
40. The cylinder 40 is connected to the frame 8 and to the
mold die 10 to effect movement of the mold die 10 and the
connected core 24 between extended and retracted positions.
While in the illustrated arrangement, the cylinder is
shown as being connected to the frame 8, and the rod extending
from the cylinder is shown as being connected to mold die 10 to
effect movement of mold die 10 and the connected core 24
relative to ~he mold die 12, in other arrangements the cylinder
could be connected in other configurations.
The molding apparatus 6 also includes means for
displacing the core 24 relative to the first mold die 10,
between a first or engaged position (shown i.n Figs. 1 and 2~,
wherein the outer surface 22 of the molded part 20 i8 engaged
with the mold die surface 14, and a second or ejected position
wherein the mold die surface 14 is separated from the outer
surface 22 of the molded part 20 (shown in Fig. 3). While
various suitable displacing means can be employed for
displacing the core 24 relative to the mold die 10, in the
disclosed construction, such displacing means comprise a
hydraulic or pneumatic cylinder 42. The cylinder 42 is
connected to the mold die 10 and to the core support assembly
28 to effect movement of the core 24 relative to the mold die
10 between engaged and ejected positions.
While in the illustrated arrangement, the cylinder is
shown as being connected to the mold die 10, and the rod
extending from the cylinder is shown as being connected to the
core support assembly 28, in other arrangements the cylinder
could be connected in other configurations.
While in the îllustrated arrangement the core support
assembly 28 is shown as comprising an ejection plate 44
connected to the cylinder 42, a core support member 46
slideably housed in core support 30 and connected on one end to
the ejection plate 44 and connected on the other end to the
actuator assembly 36, and means for separating the molded part
20 from the mold die 10, including a plurality of ejector pins
48 which are slideably housed in mold die 10, which are fixed
on one end to the ejector plate 44, and which are engageable
with the molded part 20, in other arrangements, the core
support assembly 28 could have other configurations and other
conventional ejection means.
The apparatus 6 operates as follows. With the mold
die6 10 and 12 mating to define the mold cavity 18 and with the
core 24 in the extended position (shown in Fig. 1~, foam is
injected into the cavity 18 to form the molded part 20. After
the molded part 20 has sufficiently cured, the core 24 i~
retracted from the molded part 20 by an amount sufficient to
disengage the core 24 from the inner surface 32 of the molded
part 20. Next, the mold die 10, and the connected core 24 are
displaced in a direction away from the mold die 1~ (shown in
Fig. 2). Various suitable means which are known in the ar~
can be employed to cause the outer surface 22 of the molded
part 20 to disengage from mold die surface 16 before
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disengaging with mold die surface 14. Finally, the core 24 i8
displaced relative to mold die 10 to an ejected position (shown
in Fig. 3), wherein the mold die surace 14 is separated from
the outer surface 22 of molded part 20. Various conventional
means, such as gravity/ can be used to completely remove the
molded part 20 from the molding apparatus 6.
Various features of the invention are set forth in the
following claims.
