U.S. patent application number 09/952358 was filed with the patent office on 2003-03-13 for investment molding flask assembly.
Invention is credited to Ma, Ching-Wen.
Application Number | 20030047299 09/952358 |
Document ID | / |
Family ID | 25492828 |
Filed Date | 2003-03-13 |
United States Patent
Application |
20030047299 |
Kind Code |
A1 |
Ma, Ching-Wen |
March 13, 2003 |
Investment molding flask assembly
Abstract
An investment molding flask assembly having a base with a
central positioning boss protruded from a center thereof and at
least one positioning annular groove defined therein around the
central positioning boss, and a conical sleeve formed with a small
opening end to be securely positioned on the base without any
displacement in horizontal directions by means of the central
positioning boss or the positioning annular groove. Whereby, the
conical sleeve can be readily removable from a solidified
semi-finished investment mold, and then the solidified
semi-finished investment mold is sent into an oven independently
for heating. Therefore the sleeve can be used repeatedly, and the
investment mold can be manufactured rapidly and readily.
Inventors: |
Ma, Ching-Wen; (Tainan
Hsien, TW) |
Correspondence
Address: |
Kolisch, Hartwell, Dickinson
McCormack & Heuser
Suite 200
520 S.W. Yamhill Street
Portland
OR
97204-1378
US
|
Family ID: |
25492828 |
Appl. No.: |
09/952358 |
Filed: |
September 12, 2001 |
Current U.S.
Class: |
164/376 ;
164/516 |
Current CPC
Class: |
B22C 21/00 20130101 |
Class at
Publication: |
164/376 ;
164/516 |
International
Class: |
B22C 021/00 |
Claims
What is claimed is:
1. An investment molding flask assembly comprising: a base formed
as a circular plate having a central positioning boss protruded
from a center of a top surface thereof, and at least one
positioning annular groove defined in the top surface around the
center thereof, wherein the central positioning boss is formed with
a cylindrical-shaped lower portion and a cone-shaped upper portion;
a sleeve formed as a cone having a small opening end thereof to be
securely positioned on the base without any horizontal
displacement; whereby after a wax pattern is fixed on a top end of
the central positioning boss, an investment material is charged
into an internal space of the sleeve to embed the wax pattern in
the sleeve so as to form a solidified semi-finished investment
mold, and then the solidified semi-finished investment mold is
allowed to be removed from the sleeve to be heated in an oven
independently, therefore a finished investment mold is rapidly
obtained, and the investment molding flask assembly can be used
repeatedly.
2. The investment molding flask assembly as claimed in claim 1,
wherein the base is defined with two positioning annular grooves in
the top surface around the center thereof.
3. The investment molding flask assembly as claimed in claim 1,
wherein the sleeve has a small opening end defined with a diameter
slightly larger than an outer diameter of the cylindrical-shaped
lower portion of the central positioning boss.
4. The investment molding flask assembly as claimed in claim 1,
wherein the sleeve has a small opening end defined with a diameter
to be properly inserted into the at least one positioning annular
groove.
5. The investment molding flask assembly as claimed in claim 1,
wherein a positioning recess is defined in an upper end of the
cone-shaped upper portion of the central positioning boss.
6. The investment molding flask assembly as claimed in claim 1,
wherein the sleeve is formed as a cone.
7. The investment molding flask assembly as claimed in claim 1,
wherein the sleeve is formed as a multi-stepped cone.
8. The investment molding flask assembly as claimed in claim 1,
wherein the sleeve is defined with a maximum volume mark at an
inner surface near the large opening end thereof.
9. The investment molding flask assembly as claimed in claim 1,
wherein the sleeve is defined with a maximum volume mark at an
outer surface near the large opening end thereof.
10. The investment molding flask assembly as claimed in claim 1,
wherein a gasket ring is provided on the top surface of the base
between the sleeve and the central positioning boss, an inner edge
of the gasket ring is formed therearound with a flange having an
inner cone surface extending in flush with an outer surface of the
cone-shaped upper portion of the central positioning boss.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an improved molding flask
assembly used in investment casting, particularly to an investment
molding flask assembly, which can be used repeatedly to manufacture
investment molds rapidly and readily.
[0003] 2. Description of Related Art
[0004] Lost wax investment casting is used in the making of 3
dimensioned articles such as a dental molds, metal ornaments,
sculptures etc. In a lost wax investment casting, a molding flask
assembly is normally used to form an investment mold, which is
utilized to cooperate with a spin casting apparatus to manufacture
a desired article.
[0005] As shown in FIG. 8, a conventional investment molding flask
assembly comprises a base (50) having a spherical central
positioning boss (51) protruded from a center thereof, and a
cylindrical sleeve (60) having a lower opening end seated on a top
of the base (50) and enclosing around the central positioning boss
(51). A preliminary wax pattern (70) is securely fixed on a top end
of the positioning boss (51) by means of melted wax drops (52). An
investment material (80) is charged into an internal space of the
cylindrical sleeve (60) up to an upper opening end of the
cylindrical sleeve (60) so as to completely embed the wax pattern
(70) in the cylindrical sleeve (60). After a semi-finished
investment mold is solidified, the semi-finished investment mold
with the cylindrical sleeve (60) enclosed therearound is sent into
an oven to be heated together. Whereby the wax pattern (70) is
melted and dispersed from the investment mold with the desired
molding cavities defined therein. Casting material is then directed
into the mold cavity by means of centrifugal techniques utilizing
the spin casting apparatus, and then the casting material hardens
to form a desired article.
[0006] However, because the cylindrical sleeve (60) seated on the
top of the base (50) is not retained at a fixed position, when the
investment material is poured into the cylindrical sleeve (60), the
cylindrical sleeve (60) may be moved sideways, and in this case the
wax pattern (70) may not be embedded properly in the center of the
investment mold.
[0007] The aforesaid conventional investment molding flask assembly
still has another important disadvantage. Because the sleeve (60)
is formed as a cylindrical shape, it is not easy to remove the
sleeve (60) from the semi-finished investment mold when the
investment mold is solidified, and the cylindrical sleeve (60)
enclosing the investment mold has to be sent into the oven together
with the investment mold. However, because the sleeve (60) and the
investment material normally have different thermal expansion
rates, after the investment mold and the sleeve (60) are heated
together, the sleeve (60) may be deformed or even damaged by the
overexpansion of the investment mold, or the investment mold may be
deformed, therefore the sleeve (60) can not be used repeatedly, and
the rate of finished product is low.
[0008] Therefore, it is an objective of the invention to provide an
improved investment molding flask assembly to mitigate and/or
obviate the aforementioned problems.
SUMMARY OF THE INVENTION
[0009] A first object of the present invention is to provide an
improved investment molding flask assembly, which comprises a base
having a central positioning boss protruded from a center thereof
and at least one positioning annular groove defined therein around
the center thereof, and a conical sleeve having a small opening end
thereof being securely positioned on the base by means of the
central positioning boss or a corresponding one of the at least one
positioning annular grooves without any displacement in horizontal
directions.
[0010] A second object of the present invention is to provide an
improved investment molding flask assembly, wherein the sleeve is
particularly formed as a cone having a small opening end to be
positioned on the base and a large opening end, such that when a
solidified semi-finished investment mold in the sleeve is inverted
and placed on a flat board, the sleeve is readily removable from
the solidified semi-finished investment mold. Thus, the sleeve can
be used repeatedly.
[0011] Other objects, advantages and novel features of the
invention will become more apparent from the following detailed
description when taken in conjunction with the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is an exploded perspective view of a first embodiment
of an investment molding flask assembly in accordance with the
invention;
[0013] FIG. 2 is a cross sectional view of the first embodiment of
the investment molding flask assembly in accordance with the
invention;
[0014] FIG. 3 is a cross sectional view of a second embodiment of
the investment molding flask assembly in accordance with the
invention;
[0015] FIG. 4 is a cross sectional view of a third embodiment of
the investment molding flask assembly in accordance with the
invention;
[0016] FIG. 5 is a cross sectional view of a fourth embodiment of
the investment molding flask assembly in accordance with the
invention;
[0017] FIG. 6 is a cross sectional view of a fifth embodiment of
the investment molding flask assembly in accordance with the
invention;
[0018] FIG. 7 is a cross sectional view of a sixth embodiment of
the investment molding flask assembly in accordance with the
invention; and
[0019] FIG. 8 is a cross sectional view of a conventional
investment molding flask assembly.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0020] As shown in FIG. 1, in a first embodiment of the present
invention, an investment molding flask assembly comprises a base
(10) and a sleeve (20) detachably positioned on a top surface of
the base (10).
[0021] The base (10) is formed as a circular plate having a central
positioning boss (11) protruded from a center thereof and two
positioning annular grooves (12) defined therein around the center
thereof. Wherein the central positioning boss (11) has a lower
portion thereof formed as a cylinder and an upper portion thereof
formed as a cone. An upper end of the upper portion of the central
positioning boss (11) is defined with a positioning recess (111) in
a center thereof.
[0022] The sleeve (20) is formed as a hollow cone having a small
opening end particularly dimensioned with an inner diameter
slightly larger than an outer diameter of the lower portion of the
central positioning boss (11), and a large opening end with a
diameter larger than that of the small opening end. The sleeve (20)
is further defined with a maximum volume mark (21) optionally
labeled on an inner or outer surface near the large opening end
thereof.
[0023] With reference to FIG. 2, a preliminary wax pattern (30) is
securely fixed on the upper end of the positioning boss (11) by
means of melted wax (14) filled in the positioning recess (111).
Then the small opening end of the sleeve (20) is placed on the top
surface of the base (10) and mounted around the central positioning
boss (11). Because the inner diameter of the small end of the
sleeve (20) is slightly larger than the outer diameter of the lower
portion of the central positioning boss (11), the small end of the
sleeve (20) is retained at a fixed position on the base (10)
without any horizontal displacement. Next an investment material
(40) is charged into an internal space of the sleeve (20) till its
upper level is flush with the maximum volume mark (21) so as to
embed the wax pattern (30) in the sleeve (20). After the investment
material (40) is solidified, the whole investment mold together
with the investment molding flask assembly can be inverted together
and placed on a flat board. Because the sleeve (20) is specially
designed as a cone, the solidified semi-finished investment mold is
readily separated from the flat board by gravity and a small impact
force acted upon a bottom of the base (10), whereby the sleeve (20)
is rapidly removed from the semi-finished investment mold. Finally
the semi-finished investment mold is sent into an oven to be heated
therein to obtain a finished investment mold.
[0024] In a second practicable embodiment as shown in FIG. 3, a
sleeve (20a) is formed as a two-stepped cone having a small opening
end mounted around the central positioning boss (11), so that the
sleeve (20a) is retained at a fixed position without any horizontal
displacement.
[0025] In a third embodiment as shown in FIG. 4, a sleeve (20b) is
formed as a two-stepped cone having a small opening end thereof
being properly inserted into an inner one of the annular groove
(12), so that the sleeve (20b) is retained at a fixed position
without any horizontal displacement.
[0026] In a fourth embodiment as shown in FIG. 5, a sleeve (20c) is
formed as a cone having a small end thereof being properly inserted
into the inner one of the annular grooves (12), so that the sleeve
(20c) is retained at a fixed position without any displacement.
[0027] When a large article is to be molded in the investment
molding flask assembly, a large sleeve is necessary to permit a
large wax pattern to be received in the center of the sleeve. As
shown in FIG. 6, in a fifth embodiment a conical sleeve (20d)
having a small opening end thereof is properly inserted into an
outer one of the annular grooves (12). A gasket ring (13) is
further provided on the top surface of the base (10) between the
sleeve (20d) and the central positioning boss (11) to prohibit the
investment material (14) from going into the inner one of the two
positioning annular rings (12). An inner edge of the gasket ring
(13) is therearound formed with a flange having an upper conical
surface extending flush with an outer surface of the cone-shaped
upper portion of the central positioning boss (11). Whereby a
pouring pit of the investment mold is formed with an upper opening
larger than the outer diameter of the positioning boss so as to
meet a volume requirement of a large molding cavity formed in the
investment mold.
[0028] A sixth embodiment as shown in FIG. 7 is basically same as
the fifth embodiment except for a sleeve (20e), which is formed as
a two-stepped cone.
[0029] The investment molding flask assembly of the invention has
an advantage that the sleeve is securely positioned on the base
(10) by means of the positioning boss (11) or the positioning
annular grooves (12), therefore it is retained in a fixed position
without any horizontal displacement when the investment material
(14) is charged into the internal space of the sleeve.
[0030] Another important advantage of the invention is that the
sleeve can be used repeatedly and the investment mold can be made
readily and rapidly, so that the production efficiency of the
present invention is high and the production cost of the invention
is low.
[0031] It is to be understood, however, that even though numerous
characteristics and advantages of the present invention have been
set forth in the foregoing description, together with details of
the structure and function of the invention, the disclosure is
illustrative only, and changes may be made in detail, especially in
matters of shape, size, and arrangement of parts within the
principles of the invention to the full extent indicated by the
broad general meaning of the terms in which the appended claims are
expressed.
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