U.S. patent application number 14/232438 was filed with the patent office on 2014-06-05 for method of making metal casting mold, and mold.
This patent application is currently assigned to SINTOKOGIO, LTD.. The applicant listed for this patent is Kazuyuki Nishikawa, Masanori Tomioka. Invention is credited to Kazuyuki Nishikawa, Masanori Tomioka.
Application Number | 20140150984 14/232438 |
Document ID | / |
Family ID | 47557973 |
Filed Date | 2014-06-05 |
United States Patent
Application |
20140150984 |
Kind Code |
A1 |
Nishikawa; Kazuyuki ; et
al. |
June 5, 2014 |
METHOD OF MAKING METAL CASTING MOLD, AND MOLD
Abstract
A method of making a metal casting mold is disclosed. The method
comprises the steps of: covering a support pattern by a pulp-molded
element; installing a mold flask provided with a depressurizing
device, on an upper side of the pulp-molded element; packing
heat-resistant particles inside the mold flask; providing a sealing
member on an upper surface of the mold flask so as to seal the
inside of the mold flask; depressurizing the inside of the mold
flask by the depressurizing device, to form a mold comprising the
mold flask, the heat-resistant particles, the pulp-molded element
and the sealing member; and separating the pulp-molded element from
the support pattern. A metal casting mold made by this method is
also disclosed.
Inventors: |
Nishikawa; Kazuyuki;
(Toyokawa-shi, JP) ; Tomioka; Masanori;
(Toyokawa-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Nishikawa; Kazuyuki
Tomioka; Masanori |
Toyokawa-shi
Toyokawa-shi |
|
JP
JP |
|
|
Assignee: |
SINTOKOGIO, LTD.
Nagoya-shi, Aichi
JP
|
Family ID: |
47557973 |
Appl. No.: |
14/232438 |
Filed: |
June 19, 2012 |
PCT Filed: |
June 19, 2012 |
PCT NO: |
PCT/JP2012/065601 |
371 Date: |
January 13, 2014 |
Current U.S.
Class: |
164/7.1 ;
164/253 |
Current CPC
Class: |
B22C 9/00 20130101; B22C
9/03 20130101 |
Class at
Publication: |
164/7.1 ;
164/253 |
International
Class: |
B22C 9/00 20060101
B22C009/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 15, 2011 |
JP |
2011-156286 |
Feb 28, 2012 |
JP |
2012-040944 |
Claims
1. A method of making a metal casting mold, comprising the steps
of: covering a support pattern by a pulp-molded element; installing
a mold flask provided with a depressurizing device, on an upper
side of the pulp-molded element; packing heat-resistant particles
inside the mold flask; providing a sealing member on an upper
surface of the mold flask so as to seal the inside of the mold
flask; depressurizing the inside of the mold flask by the
depressurizing device, to form a mold comprising the mold flask,
the heat-resistant particles, the pulp-molded element and the
sealing member; and separating the pulp-molded element from the
support pattern.
2. A metal casting mold comprising: a pulp-molded element covering
a support pattern; a mold flask provided with a depressurizing
device and installed on an upper side of the pulp-molded element;
heat-resistant particles packed inside the mold flask; and a
sealing member provided on an upper surface of the mold flask so as
to seal the inside of the mold flask, wherein the depressurizing
device is operable to depressurize the inside of the mold flask,
thereby forming a mold comprising the mold flask, the
heat-resistant particles, the pulp-molded element and the sealing
member, and allowing the pulp-molded element to be separated from
the support pattern.
3. The metal casting mold according to claim 2, wherein the
pulp-molded element is made of a natural fiber.
4. The metal casting mold according to claim 2, wherein the
pulp-molded element has a thickness of 0.1 mm to 2.0 mm.
5. The metal casting mold according to claim 2, wherein the
pulp-molded element is formed by a paper-making screen process.
6. The metal casting mold according to claim 2, wherein the
pulp-molded element is formed by a paper pressing process.
7. A method of making a metal casting mold, comprising the steps
of: forming a pulp-molded element by using a paper-making pattern
mold having a screen provided on a surface thereof; installing a
mold flask provided with a depressurizing device, on an upper side
of the pulp-molded element; packing heat-resistant particles inside
the mold flask; providing a sealing member on a back surface of the
mold flask so as to seal the inside of the mold flask;
depressurizing the inside of the mold flask by the depressurizing
device, to form a mold comprising the mold flask, the
heat-resistant particles, the pulp-molded element and the sealing
member; and separating the pulp-molded element from the
paper-making pattern mold.
8. A method of making a metal casting mold, comprising the steps
of: forming a pulp-molded element by using a paper-making pattern
mold having a screen provided on a surface thereof; transferring
the pulp-molded element to a support pattern; installing a mold
flask provided with a depressurizing device, on an upper side of
the pulp-molded element; packing heat-resistant particles inside
the mold flask; providing a sealing member on a back surface of the
mold flask so as to seal the inside of the mold flask;
depressurizing the inside of the mold flask by the depressurizing
device, to form a mold comprising the mold flask, the
heat-resistant particles, the pulp-molded element and the sealing
member; and separating the pulp-molded element from the support
pattern.
9. A method of making a metal casting mold, comprising the steps
of: forming a pulp-molded element having a core shape with at least
one opening, by a combinational paper-making pattern mold having a
molding surface divided into a plurality of regions and covered by
a screen; inserting a depressurizing device from the opening into
the pulp-molded element, and packing heat-resistant particles
inside the pulp-molded element; sealing the opening of the
pulp-molded element so as to prevent discharge of the
heat-resistant particles packed inside the pulp-molded element;
depressurizing the inside of the pulp-molded element by the
depressurizing device, to form a core-shaped mold comprising the
heat-resistant particles and the pulp-molded element; and
separating the core mold having the pulp-molded element as a
surface thereof, from the combinational paper-making pattern
mold.
10. The method according to claim 7, which further comprises, after
the step of packing heat-resistant particles inside the mold flask,
one selected from the group consisting of: a step of sucking air
toward the side of a back surface of the paper-making pattern mold;
a step of injecting pressurized air from the side of the back
surface of the mold flask; and a step of injecting pressurized air
from the side of the back surface of the mold flask, while sucking
air toward the side of the back surface of the paper-making pattern
mold.
11. The method according to claim 8, which further comprises, after
the step of packing heat-resistant particles inside the mold flask,
one selected from the group consisting of: a step of sucking air
toward the side of a back surface of the support pattern; a step of
injecting pressurized air from the side of the back surface of the
mold flask; and a step of injecting pressurized air from the side
of the back surface of the mold flask, while sucking air toward the
side of the back surface of the support pattern.
12. The method according to claim 9, which further comprises, after
the step of packing heat-resistant particles inside the pulp-molded
element, one selected from the group consisting of: a step of
sucking air toward the side of a back surface of the combinational
paper-making pattern mold; a step of injecting pressurized air from
the opening of the pulp-molded element; and a step of injecting
pressurized air from the opening of the pulp-molded element, while
sucking air toward the side of the back surface of the
combinational paper-making pattern mold.
13. The method according to claim 7, which further comprises a step
of heating the heat-resistant particles.
14. The method according to in claim 13, wherein a heating
temperature of the heat-resistant particles in the step of heating
the heat-resistant particles is in the range of 50.degree. C. to
200.degree. C.
15. The method according to claim 7, wherein the pulp-molded
element has a thickness of 0.1 mm to 2.0 mm.
16. The method according to claim 7, wherein the step of packing
heat-resistant particles inside the mold flask includes a sub-step
of packing heat-resistant particles under vibration.
17. The method according to claim 9, wherein the step of packing
heat-resistant particles inside the pulp-molded element includes a
sub-step of packing heat-resistant particles under vibration.
18. A metal casting mold made by the method according to claim 7,
wherein a product molding surface to be in contact with molten
metal is a three-dimensional surface composed of the pulp-molded
element, and a side behind the pulp-molded element is backed up by
the heat-resistant particles and kept in a depressurized state.
Description
TECHNICAL FIELD
[0001] The present invention relates to a method of making a metal
casting mold, and a metal casting mold.
BACKGROUND ART
[0002] Heretofore, there has been known a V-process casting method
which comprises: tightly attaching a synthetic resin film onto a
shaping surface of a master pattern member; packing dry sand on an
outer side of the synthetic resin film; placing the dry sand under
negative pressure to suck the synthetic resin film toward the dry
sand; removing the master pattern member to form a cavity; and
poring molten metal into the cavity, as described in the following
Patent Document 1. In the V-process casting method, a mold is
maintained by depressurizing an inside of the mold, i.e., a binder
for binding molding sand is not used, so that a molding-sand
mulling equipment becomes unnecessary. This also provides an
advantage that odor during casting is seldom generated, and
extraction of a product after casting is facilitated.
[0003] Patent Document 1: JP 50-8409 B
SUMMARY OF THE INVENTION
Technical Problem
[0004] However, in the V-process casting method in the above Patent
Document 1, it is necessary to apply a coating agent in order to
prevent sticking of burned molding sand to molten metal, and to dry
the applied coating agent.
[0005] The present invention has been made to solve the above
problem, and an object thereof is to provide a metal casting mold
making method and a mold which make it possible to produce a sound
cast metal product free of sticking of burned molding sand to a
surface thereof, without any need for the coating agent applying
operation and the coating agent drying operation.
Solution to the Technical Problem
[0006] In order to achieve the above object, according to a first
aspect of the present invention, there is provided a method of
making a metal casting mold. The method comprises the steps of:
covering a support pattern by a pulp-molded element; installing a
mold flask provided with a depressurizing device, on an upper side
of the pulp-molded element; packing heat-resistant particles inside
the mold flask; providing a sealing member on an upper surface of
the mold flask so as to seal the inside of the mold flask;
depressurizing the inside of the mold flask by the depressurizing
device, to form a mold comprising the mold flask, the
heat-resistant particles, the pulp-molded element and the sealing
member; and separating the pulp-molded element from the support
pattern.
[0007] In the first aspect of the present invention, the support
pattern is covered by the pulp-molded element, so that the
pulp-molded element is carbonized by heat of molten metal during
casting to function as a coating agent, which makes it possible to
prevent sticking of burned molding sand to a surface of a cast
metal product. As a result, in the first aspect of the present
invention, a need for applying the coating agent is eliminated, so
that a coating agent applying operation and a coating agent drying
operation, and any accompanying equipment, become unnecessary.
[0008] In the first aspect of the present invention, after sealing
the upper surface of the mold flask by the sealing member, the
inside of the mold flask filled with the heat-resistant particles
is depressurized, so that the mold flask, the heat-resistant
particles, the pulp-molded element and the sealing member
constituting the mold are integrated together, thereby providing
enhanced strength of the mold, which makes it possible to make a
mold using a pulp-molded element composed of natural fibers. In the
first aspect of the present invention, the pulp-molded element is
used, instead of using a synthetic resin film, so that it becomes
possible to suppress gas generation due to burning of a synthetic
resin film, and prevent surface defect of a cast metal product
which would otherwise be caused by the gas generation.
[0009] In addition, differently from a synthetic resin film, the
pulp-molded element does not use petroleum as its raw material, so
that it becomes possible to contribute to reduce environmental
burdens.
[0010] According to a second aspect of the present invention, there
is provided a metal casting mold which comprises: a pulp-molded
element covering a support pattern; a mold flask provided with a
depressurizing device and installed on an upper side of the
pulp-molded element; heat-resistant particles packed inside the
mold flask; and a sealing member provided on an upper surface of
the mold flask so as to seal the inside of the mold flask, wherein
the depressurizing device is operable to depressurize the inside of
the mold flask, thereby forming a mold comprising the mold flask,
the heat-resistant particles, the pulp-molded element and the
sealing member, and allowing the pulp-molded element to be
separated from the support pattern.
[0011] The second aspect of the present invention brings out the
same excellent functions and effects as those in the first aspect
of the present invention.
[0012] Preferably, in the second aspect of the present invention,
the pulp-molded element is made of a natural fiber.
[0013] Preferably, in the second aspect of the present invention,
the pulp-molded element has a thickness of 0.1 mm to 2.0 mm.
[0014] Preferably, in the second aspect of the present invention,
the pulp-molded element is formed by a paper-making screen
process.
[0015] Preferably, in the second aspect of the present invention,
the pulp-molded element is formed by a paper pressing process.
[0016] According to a third aspect of the present invention, there
is provided a method of making a metal casting mold. The method
comprises the steps of: forming a pulp-molded element by using a
paper-making pattern mold having a screen provided on a surface
thereof; installing a mold flask provided with a depressurizing
device, on an upper side of the pulp-molded element; packing
heat-resistant particles inside the mold flask; providing a sealing
member on a back surface of the mold flask so as to seal the inside
of the mold flask; depressurizing the inside of the mold flask by
the depressurizing device, to form a mold comprising the mold
flask, the heat-resistant particles, the pulp-molded element and
the sealing member; and separating the pulp-molded element from the
paper-making pattern mold.
[0017] According to a fourth aspect of the present invention, there
is provided a method of making a metal casting mold. The method
comprises the steps of: forming a pulp-molded element by using a
paper-making pattern mold having a screen provided on a surface
thereof; transferring the pulp-molded element to a support pattern;
installing a mold flask provided with a depressurizing device, on
an upper side of the pulp-molded element; packing heat-resistant
particles inside the mold flask; providing a sealing member on a
back surface of the mold flask so as to seal the inside of the mold
flask; depressurizing the inside of the mold flask by the
depressurizing device, to form a mold comprising the mold flask,
the heat-resistant particles, the pulp-molded element and the
sealing member; and separating the pulp-molded element from the
support pattern.
[0018] According to a fifth aspect of the present invention, there
is provided a method of making a metal casting mold. The method
comprises the steps of: forming a pulp-molded element having a core
shape with at least one opening, by a combinational paper-making
pattern mold having a molding surface divided into a plurality of
regions and covered by a screen; inserting a depressurizing device
from the opening into the pulp-molded element, and packing
heat-resistant particles inside the pulp-molded element; sealing
the opening of the pulp-molded element so as to prevent discharge
of the heat-resistant particles packed inside the pulp-molded
element; depressurizing the inside of the pulp-molded element by
the depressurizing device, to form a core-shaped mold comprising
the heat-resistant particles and the pulp-molded element; and
separating the core mold having the pulp-molded element as a
surface thereof, from the combinational paper-making pattern
mold.
[0019] Preferably, the method according to the third or fourth
aspect of the present invention further comprises, after the step
of packing heat-resistant particles inside the mold flask, one
selected from the group consisting of: a step of sucking air toward
the side of a back surface of the paper-making pattern mold or the
support pattern; a step of injecting pressurized air from the side
of the back surface of the mold flask; and a step of injecting
pressurized air from the side of the back surface of the mold
flask, while sucking air toward the side of the back surface of the
paper-making pattern mold or the support pattern.
[0020] Preferably, the method according to the fifth aspect of the
present invention further comprises, after the step of packing
heat-resistant particles inside the pulp-molded element, one
selected from the group consisting of: a step of sucking air toward
the side of a back surface of the combinational paper-making
pattern mold; a step of injecting pressurized air from the opening
of the pulp-molded element; and a step of injecting pressurized air
from the opening of the pulp-molded element, while sucking air
toward the side of the back surface of the combinational
paper-making pattern mold.
[0021] Preferably, the method according to either one of the third
to fifth aspects of the present invention further comprises a step
of heating the heat-resistant particles.
[0022] Preferably, in the third to fifth aspects of the present
invention, a heating temperature of the heat-resistant particles in
the step of heating the heat-resistant particles is in the range of
50.degree. C. to 200.degree. C.
[0023] Preferably, in the third to fifth aspects of the present
invention, the pulp-molded element has a thickness of 0.1 mm to 2.0
mm.
[0024] Preferably, in the third to fifth aspects of the present
invention, the step of packing heat-resistant particles inside the
mold flask or the pulp-molded element having a core shape includes
a sub-step of packing heat-resistant particles under vibration.
[0025] According to a sixth aspect of the present invention, there
is provided a metal casting mold made by the method according to
either one of the third to fifth aspects of the present invention,
wherein a product molding surface to be in contact with molten
metal is a three-dimensional surface composed of the pulp-molded
element, and a side behind the pulp-molded element is backed up by
the heat-resistant particles and kept in a depressurized state.
Effect of the Invention
[0026] The metal casting mold making method and the mold of the
present invention make it possible to produce a sound cast metal
product free of sticking of burned molding sand to a surface
thereof, without any need for the coating agent applying operation
and the coating agent drying operation.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] FIG. 1 is a process diagram illustrating a metal casting
mold making method according to a first embodiment of the present
invention.
[0028] FIG. 2 is a sectional view illustrating a structure of a
mold assembly in a mold-closing-state before pouring of molten
metal, in the method according the first embodiment of the present
invention.
[0029] FIG. 3 is a process diagram illustrating a metal casting
mold making method according to a second embodiment of the present
invention.
[0030] FIG. 4 is a process diagram illustrating an example of
modification of each metal casting mold making method according to
the second embodiment and the following third embodiment of the
present invention.
[0031] FIG. 5 is a process diagram illustrating a metal casting
mold making method according to a third embodiment of the present
invention.
[0032] FIG. 6 is a process diagram illustrating a metal casting
mold making method according to a fourth embodiment of the present
invention.
[0033] FIG. 7 is a process diagram illustrating an example of
modification of the metal casting mold making method according to
the fourth embodiment of the present invention.
[0034] FIG. 8 is a top plan view illustrating a mold assembly made
by the metal casting mold making methods according to the second to
fourth embodiments of the present invention.
[0035] FIG. 9 is a sectional view taken along the line A-A in FIG.
8.
[0036] FIG. 10 is a sectional view taken along the line B-B in FIG.
8.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0037] With reference to accompanying drawings, a metal casting
mold making method and a mold of the present invention will now be
described.
[0038] First of all, based on FIGS. 1 and 2, a metal casting mold
making method and a mold according to a first embodiment of the
present invention will be described.
[0039] As illustrated in FIG. 1(A), a support pattern 1, a
pulp-molded element (shielding member) 2 and a mold flask 4 are
preliminarily prepared, and then a concavoconvex surface of the
support pattern 1 is covered by the pulp-molded element 2.
[0040] In this embodiment, the support pattern 1 is a mount
configured to have an upper surface with concavities and
convexities conforming to a shape of a cavity, and bearingly
support the pulp-molded element 2 while placing the pulp-molded
element 2 to cover the concavoconvex surface. The mold flask 4 is a
frame member in which an upper surface (back surface) 4a and a
lower surface 4b are opened. The mold flask 4 is provided with a
depressurizing mechanism 6 for depressurizing an inside of the mold
flask 4.
[0041] The pulp-molded element 2 is a member which shields an
opening on the side of a mold-mating surface (lower surface 4b) of
the mold flask 4. The pulp-molded element 2 is formed in a region
which forms the mold-mating surface and a surface of the cavity,
and covers at least the concavoconvex surface of the support
pattern 1. As used here, the term "cavity (14)" means a space
defined in an inside of a mold assembly 12 obtained by mating an
upper mold 12a and a lower mold 12b together, wherein molten metal
is poured into this space to thereby produce a cast metal product
(see FIG. 2).
[0042] Then, as illustrated in FIG. 1(B), the mold flask 4 is
installed on an upper side of the pulp-molded element 2.
Subsequently, as illustrated in FIG. 1(C), heat-resistant particles
8 are packed inside the mold flask 4, i.e., into a space defined by
the pulp-molded element 2 and the mold flask 4. During the
operation of packing the heat-resistant particles 8 inside the mold
flask 4, it is preferable to vibrate the mold flask 4 to improve a
packing density of the heat-resistant particles 8 in the inside of
the mold flask 4. After completion of the packing of the
heat-resistant particles 8, a sealing member 10 is provided on the
upper surface of the mold flask 4, so that the inside of the mold
flask 4 is sealed by the sealing member 10.
[0043] Subsequently, the inside of the mold flask 4 is
depressurized by the depressurizing mechanism 6. When the inside of
the mold flask 4 is depressurized, the pulp-molded element 2 is
sucked toward the heat-resistant particles 8, and thereby a mold is
formed in which the mold flask 4, the heat-resistant particles 8,
the pulp-molded element 2 and the sealing member 10 are integrated
together.
[0044] In this embodiment, the depressurizing mechanism 6
comprises: a plurality of pipes 6a each composed of a net with fine
meshes precluding passage of the heat-resistant particles 8 as
described later and disposed in the inside of the mold flask 4; and
a suction chamber 6b and a suction port 6c which are formed inside
the mold flask 4 and with which opposite ends of each of the
plurality of pipes 6a communicate. The suction port 6c is connected
to a suction device (not illustrated) provided externally, to allow
the inside of the mold flask 4 to be sucked (depressurized) via the
pipes 6a.
[0045] Subsequently, as illustrated in FIG. 1(D), in a state in
which the depressurization of the inside of the mold flask 4 is
maintained, the pulp-molded element 2 is separated from the support
pattern 1. The inside of the mold flask 4 will be continuously
depressurized by the depressurizing mechanism 6.
[0046] FIG. 2 illustrates a mold assembly 12 obtained by mating
together an upper mold 12a and a lower mold 12b each made by the
process illustrated in FIG. 1.
[0047] In this embodiment, the pulp-molded element 2 is
preliminarily molded by a paper-making screen process or a paper
pressing process. As used here, the teem "paper-making screen
process" means a process of: collecting a raw material dissolved in
water and formed as slurry, by a screen (metal mesh) bonded onto a
pattern mold; and drying the collected slurry to obtain a
pulp-molded element having a desired shape. On the other hand, the
"paper pressing process" is a process for obtaining a pulp-molded
element having a desired shape by pressing a planar-shaped paper.
The paper-making screen process has an advantage of being able to
obtain a pulp-molded element having a complicated shape. On the
other hand, the paper pressing process has an advantage of being
able to reduce a production cost, although an obtainable shape is
limited to a simple shape.
[0048] As a raw material for the pulp-molded element 2, it is
possible to use wood pulp typified by paper pulp, and other natural
fiber pulps, such as cotton pulp, cotton linter pulp, bamboo pulp,
straw pulp and other non-wood pulps. These raw materials for the
pulp-molded element may be virgin pulp, or may be recycled/used
paper pulp or mixed pulp of them. The recycled-paper pulp is
preferable in view of environment and production cost. It is also
possible to use non-natural fibers, such as synthetic resin fibers,
although it cannot be said that they are desirable in view of
environment and production cost.
[0049] The pulp-molded element 2 is formed to have a thickness of
0.1 mm to 2.0 mm. If the thickness is set to be less than 0.1 mm, a
strength of the pulp-molded element 2 is deteriorated, which causes
a problem that tearing, wrinkle, etc., occurs during installation
onto the support pattern 1. On the other hand, if the thickness is
greater than 2.0 mm, an unreasonable situation occurs, for example,
in which a size of a resulting cast mold product is excessively
increased by a value corresponding to a reduction in thickness of
the pulp-molded element due to its carbonization, volume reduction
and thinning caused by heat of molten metal during casting,
although there is no major problem in production of cast metal.
[0050] As a material for the pulp-molded element 2, a type having
an average pulp fiber length of 0.3 mm to 4.0 mm is used. If the
length is less than 0.3 mm, the strength of the pulp-molded element
is deteriorated. On the other hand, if the length is greater than
4.0 mm, unevenness in thickness of a resulting paper is more likely
to occur.
[0051] Preferably, the pulp-molded element 2 for use in a mold in
this embodiment has an average pulp fiber length of about 2 mm, and
a thickness of 1 mm, in view of handleability, gas permeability,
releasability of a cast metal product from sand, etc.
[0052] As described above, in the metal casting mold making method
and the mold according to the first embodiment of the present
invention, the pulp-molded element is used as a cavity surface, so
that the pulp-molded element is carbonized by heat of molten metal
during casting to function as a coating agent, which makes it
possible to prevent sticking of burned molding sand to a surface of
a cast metal product. As a result, a need for applying the coating
agent is eliminated, so that a coating agent applying operation and
a coating agent drying operation, and any accompanying equipment,
become unnecessary.
[0053] In the first embodiment, after sealing openings of the lower
and upper surfaces of the mold flask by the pulp-molded element
(shielding member) and the sealing member, the inside of the mold
flask filled with the heat-resistant particles is depressurized, so
that a strength of a mold is increased, which makes it possible to
make a mold using a pulp-molded element composed of natural fibers.
In the first embodiment, differently from the V-process casting
method, no synthetic resin film is used as a shielding member, so
that it becomes possible to suppress gas generation due to burning
of a synthetic resin film, and prevent surface defect of a cast
metal product which would otherwise be caused by the gas
generation. In addition, differently from a synthetic resin film,
the pulp-molded element using natural fibers in the first
embodiment does not use petroleum as its raw material, so that it
becomes possible to contribute to reduce environmental burdens.
[0054] In the first embodiment, binder-free particles, such as
binder-free sand, are used as the heat-resistant particles to be
packed inside the mold flask, so that odor or harmful gas is not
generated, which eliminates a need for any accompanying equipment,
such as an exhaust-gas treatment device. In addition, the
heat-resistant particles, such as sand, have no need for adding
binder thereto, so that it is not necessary to perform a treatment
using a mulling machine, etc., which provides large advantageous
effects, such as reduction in the number of processes, reduction of
apparatuses, and reduction of management operations. In the first
embodiment, when the mold is disassembled, the molding sand can be
broken down by releasing the depressurization of the inside of the
mold flask to set a pressure therein to normal pressure, so that
the breaking down does not require vibration, hammering or the
like, and dust diffusion is minor, which makes it possible to scale
down accompanying equipment, such as a dust collector.
[0055] Next, based on FIG. 3, a metal casting mold making method
and a mold according to a second embodiment of the present
invention will be described.
[0056] First of all, as illustrated in FIG. 3(A), in order to
obtain a desired cast metal product, a three-dimensionally-shaped
pulp-molded element 22 is formed by a paper-making screen process
using a paper-making pattern mold 20 provided with a screen (metal
mesh) on a surface thereof Then, as illustrated in FIG. 3(B), a
mold flask 28 having opened upper and lower surfaces and comprising
a depressurizing mechanism 26 capable of depressurizing an inside
thereof is provided on an upper surface of the pulp-molded element
22 in such a manner as to allow aftermentioned heat-resistant
particles 24 to be packed therein. The depressurizing mechanism 26
is the same type as the depressurizing mechanism 6 in the first
embodiment.
[0057] Subsequently, after providing a molten metal pouring sprue,
a flow-off for molten metal, etc., according to need,
heat-resistant particles 24 are packed into a space surrounded by
the pulp-molded element 22 and the mold flask 28, as illustrated in
FIG. 3(C). Then, as illustrated in FIG. 3(D), a back surface (upper
surface) of the mold flask 28 is sealed against atmospheric air by
a sealing member 30, such as a synthetic resin film, so as to allow
an inside of the mold flask 28 to be depressurized. Subsequently,
the inside of the mold flask 28 is depressurized through the
depressurizing mechanism 26 to form a mold in which the mold flask
28, the heat-resistant particles 24, the pulp-molded element 22 and
the sealing member 30 are integrated together. Then, as illustrated
in FIG. 3(E), in a state in which the depressurization of the
inside of the mold flask 28 is maintained to continually suck the
pulp-molded element 22 toward the mold flask 28, the pulp-molded
element 22 is released from the paper-making pattern mold 20.
[0058] During the mold release, air may be injected from the side
of a back surface (lower surface) of the paper-making pattern mold
20 to facilitate the release. Although a synthetic resin film is
used as the sealing member in this embodiment, the sealing member
is not limited thereto, but any other suitable material, such as an
iron plate or a rubber sheet, may be used. Further, as the
heat-resistant particles 24, casting sand, such as silica sand, may
be used.
[0059] In the second embodiment, when the pulp-molded element 22
absorbs moisture during the above process, it can become difficult
to achieve a desirable situation during casting. Thus, it is
necessary to dry the pulp-molded element 22. For this purpose, it
is preferable that, after forming the pulp-molded element 22, the
heat-resistant particles 24 to be packed are heated up to a
temperature of 50.degree. C. to 200.degree. C., and the pulp-molded
element 22 is dried by heat of the heat-resistant particles 24. In
this case, as compared to a conventional drying method, a drying
time for the pulp-molded element 22 is shortened, and problems,
such as deformation and residual water due to uneven heating, are
solved. The heating temperature of the heat-resistant particles 24
is set in the range of 50.degree. C. to 200.degree. C., because, if
the temperature is less than 50.degree. C., an effect of drying the
pulp-molded element 22 is insufficient, whereas, if the temperature
is greater than 200.degree. C., water in the pulp-molded element 22
is instantaneously vaporized immediately after a contact between
the heat-resistant particles 24 and the pulp-molded element 22,
which is likely to cause scattering of the heat-resistant particles
24.
[0060] In the second embodiment, after the step of packing the
heat-resistant particles 24 inside the mold flask 28, a step of
sucking air toward the side of the back surface (lower surface) of
the paper-making pattern mold 20, or a step of injecting
pressurized air from the back surface (upper surface) of the mold
flask 28, or a step of injecting pressurized air from the side of
the back surface (upper surface) of the mold flask 28, while
sucking air toward the side of the back surface (lower surface) of
the paper-making pattern mold 20, as illustrated in FIG. 4, may be
performed. In the embodiment illustrated in FIG. 4, a pressurized
air supply box 32 is provided on the back surface (upper surface)
of the mold flask 28, to inject pressurized air, while sucking air
toward the side of the back surface (lower surface) of the
paper-making pattern mold 20. When airflow is formed in this way,
drying of the pulp-molded element 22 can be further
accelerated.
[0061] Next, based on FIG. 5, a metal casting mold making method
according to a third embodiment of the present invention will be
described.
[0062] In the third embodiment, after forming a pulp-molded element
22 by a paper-making pattern mold 20, as illustrated in FIG. 5(A),
a support pattern 34 is put over the paper-making pattern mold 20.
The support pattern 34 has a structure obtained by inverting a
configuration of the paper-making pattern mold 20, i.e., has a
surface profile capable of coming into close contact with the
pulp-molded element 22.
[0063] Then, after transferring the pulp-molded element 22 from the
paper-making pattern mold 20 to the support pattern 34, as
illustrated in FIG. 5(B), a mold flask 28 is provided on the
pulp-molded element 22 on an upper surface of the support pattern
34, whereafter, in the same manner as that in the second embodiment
illustrated in FIG. 3, a mold is fabricated by; packing
heat-resistant particles 24 (see FIG. 5(D)); sealing a back surface
(upper surface) of the mold flask 28 by a sealing member 30 (see
FIG. 5(E)); depressurizing an inside of the mold flask 28 to form a
mold in which the mold flask 28, the heat-resistant particles 24,
the pulp-molded element 22 and the sealing member 30 are integrated
together; and releasing the pulp-molded element 22 from the
paper-making pattern mold 20 while maintaining the depressurization
(see FIG. 5(F)). During the pattern release, air may be injected
from the side of a lower surface of the support pattern 34 to
facilitate the release.
[0064] In the third embodiment, it is preferable that a heating
temperature of the heat-resistant particles 24 is set in the range
of 50.degree. C. to 200.degree. C., and the pulp-molded element 22
is dried by heat of the heat-resistant particles 24, as with the
second embodiment. Further, as illustrated in FIG. 4, after the
step of packing the heat-resistant particles 24 inside the mold
flask 28, a step of sucking air toward the side of a back surface
(lower surface) of the support pattern 34, or a step of injecting
pressurized air from the side of the back surface (upper surface)
of the mold flask 28, or a step of injecting pressurized air from
the side of the back surface (upper surface) of the mold flask 28,
while sucking air toward the side of the back surface (lower
surface) of the support pattern 34, as illustrated in FIG. 4, may
be performed.
[0065] Next, based on FIG. 6, a metal casting mold making method
according to a fourth embodiment of the present invention will be
described. The fourth embodiment relates to a process for making a
metal casting core mold.
[0066] First of all, as illustrated in FIG. 6(A), a bag-like
pulp-molded element 42 is formed by a combinational paper-making
pattern mold 40 which has a molding surface divided into two or
more regions and covered by a screen (metal mesh), and defines
therein a core shape having at least one core print region opened
to the outside.
[0067] Then, as illustrated in FIG. 6(B), a depressurizing
mechanism 44 for depressurizing an inside of the bag-like
pulp-molded element 42 is inserted from the opening, and
heat-resistant particles 46 are packed. Subsequently, as
illustrated in FIG. 6(C), a part of the heat-resistant particles 46
adjacent to the opening are impregnated with a binder 48 such as
wax, and bound to seal the opening so as to prevent discharge of
the heat-resistant particles 46 packed inside the bag-like
pulp-molded element 42. Subsequently, the inside of the bag-like
pulp-molded element 42 is depressurized through the depressurizing
mechanism 44 to form a mold in which the heat-resistant particles
46 and the pulp-molded element 42 are integrated together. Then, as
illustrated in FIG. 6(D), in a state in which the depressurization
of the inside of the bag-like pulp-molded element 42 is maintained,
the core mold 50 having the bag-like pulp-molded element 42 as a
surface thereof is released from the combinational paper-making
pattern mold 40.
[0068] During the mold release, as illustrated in FIG. 6(D), air
may be injected (blown off) from the side of a back surface (outer
surface) of the paper-making pattern mold 40 to facilitate the
release. As an alternative method for sealing the opening so as to
prevent discharge of the heat-resistant particles packed inside the
pulp-molded element, the opening may be closed by using a sealing
member capable of sealing atmospheric air, such as a synthetic
resin film.
[0069] In the fourth embodiment, in view of drying of the bag-like
pulp-molded element 42, it is preferable that a heating temperature
of the heat-resistant particles 46 to be packed is set in the range
of 50.degree. C. to 200.degree. C. Further, after the step of
packing the heat-resistant particles 46, a step of sucking air
toward the side of the back surface of the combinational
paper-making pattern mold 40, or a step of injecting pressurized
air from the opening of the bag-like pulp-molded element 42, or a
step of injecting pressurized air from the opening of the bag-like
pulp-molded element 42, while sucking air toward the side of the
back surface of the combinational paper-making pattern mold 40, as
illustrated in FIG. 7, may be performed. As an alternative method
for injecting pressurized air, pressurized air may be injected from
a connection section 44c with to a suction device (not
illustrated), by using the depressurizing mechanism 44.
Alternatively, for example, pressurized air may be injected using a
pressurized air supply box (see FIG. 4) covering the opening of the
pulp-molded element 42, or may be injected from a nozzle or the
like directly into the opening of the pulp-molded element 42.
[0070] In the second to fourth embodiments, dry thicknesses of the
pulp-molded elements 22, 42 are preferably in the range of 0.1 to
2.0 mm. If the thickness is less than 0.1 mm, a stable pulp-molded
element cannot be obtained, specifically, a partial tearing is more
likely to occur. On the other hand, if the thickness is greater
than 2.0 mm, an unreasonable situation occurs, for example, in
which a size of a resulting cast mold product is excessively
increased by a value corresponding to a reduction in thickness of
the pulp-molded element due to its carbonization, volume reduction
and thinning caused by heat of molten metal during casting,
although there is no major problem in production of cast metal.
[0071] In the second to fourth embodiments, a suitable average pulp
fiber length of the pulp-molded element is in the range of 0.3 mm
to 4.0 mm. If the length is less than 0.3 mm, the strength of the
pulp-molded element is deteriorated. On the other hand, if the
length is greater than 4.0 mm, unevenness in thickness of a
resulting paper is more likely to occur. Preferably, the
pulp-molded element has a fiber length of about 0.8 to 3.5 mm, and
a thickness of 0.5 to 1.5 mm, in view of handleability during paper
making, gas permeability, releasability of a cast metal product
from sand, etc.
[0072] In the second to fourth embodiments, with a view to
enhancing the packing density of the heat-resistant particles (24,
46), it is preferable to pack the particles while applying
vibration to the mold flask. Although no serious packing defect
occurs in artificial casting sand having an almost uniform
spherical shape, the packing with vibration is extremely effective,
particularly, in casting sand having non-uniform shapes, such as
silica sand. In addition to casting sand, it is possible to use, as
the heat-resistant particles (24, 46), commonly-used sand or
gravel, glass beads, ceramic beads, or metal particles.
[0073] Next, based on FIGS. 8 to 10, a metal molding mold assembly
made by the second to fourth embodiments will be described. FIG. 8
is a top plan view illustrating the mold assembly made by the metal
casting mold making methods according to the second to fourth
embodiments of the present invention, and FIG. 9 and FIG. 10 are,
respectively, a sectional view taken along the line A-A in FIG. 8,
and a sectional view taken along the line B-B in FIG. 8.
[0074] As illustrated in FIGS. 8 to 10, the metal molding mold
assembly comprises a main mold 52 as a mold assembly made by any
one of the second to third embodiments, and a core mold 50 as a
mold made by the fourth embodiment. In each of the molds 50, 52, a
product molding surface to be in contact with molten metal is a
three-dimensional surface defined by the pulp-molded element (22,
42), and a side behind the pulp-molded element (22, 42) is backed
up by the heat-resistant particles (24, 46) and kept in a
depressurized state.
[0075] In such a metal molding mold assembly (50, 52), a surface to
be in contact with high-temperature molten metal is composed of the
pulp-molded element (22, 42). Although the pulp-molded element (22,
42) is carbonized during casting, generation of harmful gas and
odor can be mostly suppressed by employing natural fiber. Further,
the heat-resistant particles (24, 46) are binder-free, so that odor
or harmful gas is not generated, which eliminates a need for any
accompanying equipment, such as an exhaust-gas treatment device. In
addition, the heat-resistant particles (24, 46) have no need for
adding binder thereto, so that it is not necessary to perform a
treatment using a mulling machine, etc., which provides large
advantageous effects, such as reduction in the number of processes,
reduction of apparatuses, and reduction of management
operations.
[0076] When the mold is disassembled, the casting sand can be
broken down by releasing the depressurization of an inside of each
mold to set a pressure therein to normal pressure. Although it is
observed that a carbonized layer of the pulp-molded element loosely
adheres onto a cast metal product, the cast metal product can be
readily separated from the heat-resistant particles. Further, the
breaking down does not require vibration, hammering or the like,
and dust diffusion is low, which provides an advantage that there
is almost no need to take into account accompanying equipment, such
as a dust collector.
EXAMPLES
[0077] Examples 1 to 5 of the first embodiment of the present
invention will be described below.
Example 1
[0078] As a molding material for a pulp-molded element, an aqueous
solution of bleached kraft paper recycled-paper pulp (average fiber
length: 3.5 mm) having a solid content concentration of about 1
weight % was preliminarily prepared by experimentally defiberizing
bleached kraft paper in the form of a pulp slurry.
[0079] As a paper-making pattern mold, a paper-making aluminum
pattern mold having a 100-mesh screen bonded onto a surface thereof
was preliminarily prepared.
[0080] In order to form a pulp-molded element, the paper-making
aluminum pattern mold was immersed in the pulp slurry while
stirring the pulp slurry, and vacuum suction of the pulp slurry was
done so that the pulp was sucked and layered on the paper-making
aluminum pattern mold, whereafter the paper-making aluminum pattern
was extracted from the pulp slurry.
[0081] Then, in order to dehydrate the pulp-molded element, one of
a pair of compressing mating dies was put over the paper-making
aluminum pattern mold having the pulp-molded element layered
thereon to transfer the pulp-molded element to the compressing
mating die, and then the other compressing mating die was mated
therewith to dry the pulp-molded element while blowing off hot air.
In this dried state, the pulp-molded element has a thickness of
about 0.5 mm.
[0082] In regard to a configuration of the pulp-molded element,
walls of a gating system for casting, such as a sprue, a runner and
an ingate, were formed integrally together with a cavity surface
for forming a product. However, the walls of the gating system are
not necessarily formed integrally together therewith. In the case
where the walls of the gating system are not formed integrally
together with the pulp-molded element, before packing
heat-resistant particles inside a mold flask, pattern elements made
by paper pulp or foamed polystyrene may be connected to the
pulp-molded element.
[0083] In the same manner, another pulp-molded element for the
other mating mold of the mold assembly was formed.
[0084] Then, a mold making operation was performed. The pulp-molded
element was put on a support pattern composed of a resin block so
as not to form a gap therebetween. When there is a gap between the
support pattern and the pulp-molded element, a certain level of
dimensional adjustment can be performed by pressing the pulp-molded
element against the support pattern while spraying water onto the
pulp-molded element, to allow them to conform to each other. In
this example, with a view to enhancing the packing density of
heat-resistant particles packed inside a mold flask, the support
pattern was placed on a vibration table.
[0085] Then, a mold flask equipped with a depressurizing mechanism
capable of depressurizing an inside of the mold flask was put on
the pulp-molded element, and heat-resistant particles are packed
inside the mold flask while operating the vibration table. As the
heat-resistant particles, artificial casting sand (NAIGAI CERABEADS
650 produced by Itochu Ceratech Corporation) was used.
[0086] Subsequently, after putting a synthetic resin film having a
thickness of about 0.05 mm, over an upper surface of the mold flask
to isolate the inside of the mold flask from atmospheric air, the
inside of the mold flask was depressurized by a vacuum pump, and
the pulp-molded element was released from the support pattern. The
inside of the mold flask was depressurized to 250 to 300 mm Hg. If
there is difficulty in releasing the pulp-molded element (shielding
member) due to its air permeability, the support pattern may have a
mechanism for blowing off air therefrom to facilitate the pattern
release.
[0087] In the same manner, the other mating mold was made to
complete the metal molding mold assembly.
[0088] Cast iron at about 1400.degree. C. was cast into the mold
assembly made in the above manner.
[0089] As a result, during casting, dust diffusion seldom occurred,
and no odor was felt. After cooling, the depressurization of the
mold was released, and a cast metal product was extracted. The mold
could be disassembled without dust diffusion and odor. Further,
only a thin carbonized layer loosely adhered on a surface of the
cast metal product, and no adhesion on sand was observed. The cast
metal product could be cast with sound quality without blow hole,
pin hole, sand burning, etc.
Example 2
[0090] As a molding material for a pulp-molded element, an aqueous
solution of milk carton recycled-paper pulp (average fiber length:
2 mm) having a solid content concentration of about 1 weight % was
preliminarily prepared by experimentally defiberizing milk carton
in the form of a pulp slurry and removing therefrom a film and
others laminated thereon.
[0091] The pulp-molded element was formed in the same manner as
that in Example 1. A thickness of the pulp-molded element was set
to about 1 mm. In this example, the pulp-molded element is
fabricated together with a gating system, such as a sprue, a runner
and an ingate.
[0092] Then, a mold making operation and a casting operation were
performed in the same manner as that in Example 1.
[0093] As a result, through the entire process, for example, during
casting and during mold disassembly, dust diffusion and odor seldom
occurred without causing pollution in working environment, etc. In
addition, sound quality could be ensured in a resulting cast metal
product.
Example 3
[0094] As a molding material for a pulp-molded element, an aqueous
solution of newspaper recycled-paper pulp (average fiber length:
0.8 mm) having a solid content concentration of about 1 weight %
was preliminarily prepared by experimentally defiberizing newspaper
in the form of a pulp slurry and deinking the pulp slurry.
[0095] The pulp-molded element was formed in the same manner as
that in Example 1. A thickness of the pulp-molded element was set
to about 1.5 mm. In this example, the pulp-molded element is
fabricated together with a gating system, such as a sprue, a runner
and an ingate.
[0096] Then, a mold making operation and a casting operation were
performed in the same manner as that in Example 1, except that
silica sand (Australian Flattery sand) was used as the
heat-resistant particles.
[0097] As a result, through the entire process, for example, during
casting and during mold disassembly, generation of odor seldom
occurred. However, as compared to the artificial casting sand in
Example 1, dust diffusion was slightly observed but it was not at a
level exerting an influence on working environment.
[0098] A resulting cast metal product was obtained with sound
quality, as with Examples 1 and 2.
Example 4
[0099] As a molding material for a pulp-molded element, an aqueous
solution of newspaper recycled-paper pulp (average fiber length:
0.4 mm) having a solid content concentration of about 1 weight %
was preliminarily prepared by experimentally defiberizing newspaper
in the form of a pulp slurry and deinking the pulp slurry.
[0100] The pulp-molded element was formed in the same manner as
that in Example 1. A thickness of the pulp-molded element was set
to about 2.5 mm. In this example, the pulp-molded element is
fabricated together with a gating system, such as a sprue, a runner
and an ingate.
[0101] Then, a mold making operation and a casting operation were
performed in the same manner as that in Example 3. As a result,
through the entire process, for example, during casting and during
mold disassembly, generation of odor seldom occurred. However, as
compared to the artificial casting sand in Example 1, dust
diffusion was slightly observed but it was not at a level exerting
an influence on working environment.
[0102] A resulting cast metal product was obtained with sound
quality, as with Example 3. However, because the thickness of the
pulp-molded element was 2.5 mm, the occurrence of burrs on a
mold-mating surface was observed.
Example 5
[0103] In this example, a pulp-molded element was formed in the
same manner as that in Example 4, except that an outer peripheral
portion of the pulp-molded element around a product molding surface
is pressed from the side of a back surface thereof in a range of
about 3 mm width by using a separately prepared jig, to allow of
the outer peripheral portion of the pulp-molded element to have a
wall thickness of about 0.8 mm. In this example, the pulp-molded
element is fabricated together with a gating system, such as a
sprue, a runner and an ingate.
[0104] Then, a mold making operation and a casting operation were
performed in the same manner as that in Example 4.
[0105] As a result, a resulting cast metal product was
significantly improved in terms of burrs.
[0106] Next, Examples 6 to 9 of the second to fourth embodiments of
the present invention will be described.
Example 6
[0107] In advance of fabrication of a pulp-molded element, an
aqueous solution of bleached kraft paper recycled-paper pulp
(average fiber length: 3.5 mm) having a solid content concentration
of about 0.5 weight % was preliminarily prepared by experimentally
defiberizing bleached kraft paper in the form of a pulp slurry. As
a paper-making pattern mold, a paper-making aluminum pattern mold
having a 100-mesh screen bonded onto a surface thereof was
preliminarily prepared.
[0108] In order to form a pulp-molded element, the paper-making
aluminum pattern mold was immersed in the pulp slurry while
stirring the pulp slurry, and vacuum suction of the pulp slurry was
done so that the pulp was sucked and layered on the paper-making
aluminum pattern mold, whereafter the paper-making aluminum pattern
mold was extracted from the pulp slurry.
[0109] Then, a mold flask capable of allowing an inside thereof to
be depressurized was put on an upper side of the pulp-molded
element, and artificial casting sand (NAIGAI CERABEADS 650 produced
by Itochu Ceratech Corporation) serving as heat-resistant particles
were heated up to about 60.degree. C. and packed into a space
surrounded by the pulp-molded element and the mold flask, while
operating a vibration table to enhance a packing density of the
artificial casting sand. Subsequently, air was sucked toward the
side of a back surface of the paper-making pattern mold to generate
airflow passing through the mold flask. A period of time of the
airflow generation was about 60 seconds.
[0110] Subsequently, after putting a synthetic resin film having a
thickness of about 0.05 mm, over a back surface of the mold flask
to isolate the inside of the mold flask from atmospheric air, the
inside of the mold flask was depressurized by a vacuum pump, and
the pulp-molded element was released from the paper-making pattern
mold. The pulp-molded element has air-permeability, and therefore
it is necessary to take measures to facilitate the mold release. In
this regard, the pulp-molded element could be easily released from
the paper-making pattern mold by injecting air from the side of the
back surface of the paper-making pattern mold during the mold
release. In this state, a thickness of the pulp-molded element was
about 0.5 mm.
[0111] In regard to a configuration of the pulp-molded element,
walls of a sprue, a runner, an ingate and others required for
casting were formed integrally together with a product molding
surface (cavity surface). Then, a pair of mating molds each having
the pulp-molded element as a molding surface were made in the same
way, and mated together to make up a casting mold assembly. Cast
iron at about 1400.degree. C. was cast into the mold assembly.
[0112] As a result, during casting, dust diffusion seldom occurred,
and no odor was felt. After cooling, the depressurization of the
mold was released, and a cast metal product was extracted. The mold
could be disassembled without dust diffusion and odor. Further,
only a thin carbonized layer loosely adhered on a surface of the
cast metal product, and no adhesion on sand was observed. The cast
metal product could be cast with sound quality without blow hole,
pin hole, sand burning, etc.
Example 7
[0113] In advance of fabrication of a pulp-molded element, an
aqueous solution of milk carton recycled-paper pulp (average fiber
length: 2 mm) having a solid content concentration of about 0.5
weight % was preliminarily prepared by experimentally defiberizing
milk carton in the form of a pulp slurry and removing therefrom a
film and others laminated thereon.
[0114] A mold was fabricated in the same manner as that in Example
6. Specifically, the thickness of the pulp-molded element was set
to about 1 mm, and the temperature of the heat-resistant particles
was set to about 100.degree. C. Further, the period of time of the
in-mold airflow generation for drying the pulp-molded element was
set to about 90 seconds. A casting operation was performed in the
same manner as that in Example 6.
[0115] As a result, through the entire process, for example, during
casting and during mold disassembly, dust diffusion and odor seldom
occurred without causing pollution in working environment, etc. In
addition, sound quality could be ensured in a resulting cast metal
product.
Example 8
[0116] In advance of fabrication of a pulp-molded element, an
aqueous solution of newspaper recycled-paper pulp (average fiber
length: 0.8 mm) having a solid content concentration of about 0.5
weight % was preliminarily prepared by experimentally defiberizing
newspaper in the form of a pulp slurry and deinking the pulp
slurry. A mold was fabricated in the same manner as that in Example
6, except that silica sand (Australian Flattery sand) was used as
the heat-resistant particles, and packed inside the mold flask
while applying vibration thereto. The thickness of the pulp-molded
element was set to about 1.5 mm, and the temperature of the
heat-resistant particles was set to about 150.degree. C. Further,
the period of time of the in-mold airflow generation for drying the
pulp-molded element was set to about 60 seconds.
[0117] As a result, through the entire process, for example, during
casting and during mold disassembly, generation of dust and odor
seldom occurred. However, as compared to the artificial casting
sand in Example 6, dust diffusion was slightly observed. A
resulting cast metal product was obtained with sound quality, as
with Examples 6 and 7.
Example 9
[0118] In advance of fabrication of a pulp-molded element, an
aqueous solution of milk carton recycled-paper pulp (average fiber
length: 2 mm) having a solid content concentration of about 0.5
weight % was preliminarily prepared by experimentally defiberizing
milk carton in the form of a pulp slurry and removing therefrom a
film and others laminated thereon.
[0119] In advance of fabrication of a core mold, a core shape
illustrated in FIG. 6 was formed by a two-divided paper-making
pattern mold. A 100-mesh screen was put over a paper-making
surface. A core print region of the core mold was opened to the
outside to allow the pulp-molded element forming slurry to get in
and out through this opening. In an operation of forming the
pulp-molded element, the two-divided paper-making pattern mold was
set in a closing state, and immersed in the slurry bath. The slurry
was entered from the opening of the core print region, and sucked
toward the side of a back surface of the paper-making pattern mold
to thereby form a pulp-molded element.
[0120] Then, the paper-making pattern mold was extracted from the
slurry bath, and heat-resistant particles heated up to 100.degree.
C. were packed from the opening into the mold. Concurrently, a
pipe-shaped depressurizing mechanism was inserted so as to
depressurize an inside of the mold. Subsequently, pressurized air
was injected from the opening into the mold, while sucking air
toward the side of the back surface of the paper-making pattern
mold, to dry the pulp-molded element. A period of time of the
pressurization and suction was set to about 60 seconds.
[0121] Then, a core mold was fabricated by: putting a synthetic
resin film having a thickness of about 0.05 mm, over the opening to
shield the opening to allow the inside of the mold to be
depressurized; depressurizing the inside of the mold through the
depressurizing mechanism; and simultaneously injecting air between
the pulp-molded element and the paper-making pattern mold to
separate them from each other. A thickness of the pulp-molded
element was set to about 1 mm.
[0122] Separately from the above operations, upper and lower main
cores fabricated in the same manner as that in Example 7 were
preliminarily prepared. Then, the above core mold was installed in
the lower mold, and the upper mold was put thereon to make up a
casting mold assembly as illustrated in FIG. 8. A casting operation
was performed in the same manner as that in Example 6.
[0123] As a result, through the entire process, for example, during
casting and during mold disassembly, generation of dust and odor
seldom occurred without causing pollution in working environment,
etc. In addition, sound quality could be ensured in a resulting
cast metal product.
EXPLANATION OF REFERENCE NUMERALS
[0124] 1, 34: support pattern
[0125] 2, 22, 42: pulp-molded element
[0126] 4, 28: mold flask
[0127] 6, 26, 44: depressurizing mechanism (depressurizing
device)
[0128] 8, 24, 46: heat-resistant particles
[0129] 10, 30: sealing member
[0130] 20, 40: paper-making pattern mold
* * * * *