TECHNICAL FIELD OF THE INVENTION
[0001] This invention relates to an improvement in precision and productivity in a casting
method in which gravity pouring of melt is carried out from the upper mold part or
lateral part of a gas permeable mold.
BACKGROUND OF THE ART
[0002] A casting mold made from sand particles has been most commonly used as a gas permeable
mold, and meanwhile, casting molds made from ceramic particles or metallic particles
have been used extensively. A casting mold made of a material having even little air
permeability such as calcium sulfate is deemed as the gas permeable mold, if it is
mixed with a material having air permeability or made air permeability even in part.
Where even an impervious metallic mold is provided with air holes or vent holes, it
is also deemed as a type of gas permeable mold. Thus, the gas permeable mold according
to the present invention includes these kinds of gas permeable molds.
[0003] A cavity in the casting mold is generally comprised of a sprue, a sprue runner, a
riser and a product portion. There may be disposed an overflow for removing excessive
melt from a product portion, but a structure basically comprising the sprue, sprue
runner, riser and product portion will be described here for simplicity.
[0004] In all kinds of casting methods including as a general casting method and a peculiar
casting method such as a vacuum casting method, pouring of the melt is completed upon
filling of four cavity portions with the melt. After completing solidification of
the melt, only the intended cast part molded in the product portion of these four
portions is detached therefrom to taken out from the product portion, and then, the
molded cast part is finished up to obtain a final cast product.
[0005] That is, the molded parts in the sprue, sprue runner and riser other than the product
portion are separated as unnecessary cast parts from the intended cast part and subject
to remelting as return materials. Although the unnecessary cast part formed in the
riser is howbeit necessary for securing structural integrity of the product portion
in a solidification process, the unnecessary cast parts in the sprue runner and sprue
serve merely for filling the cavity with the melt.
[0006] Since volume expansion occurs due to crystallization of graphite in the solidification
process in iron casting and so forth, it has been known that contraction quantity
of the melt is partially compensated, so that a cast product having high integrity
can be obtained under some conditions without using a riser. In this instance, the
riser is also unnecessary, and it is only required to fill only the product portion
with the melt.
[0007] As noted above, all the conventional casting methods adopt a pouring process for
pouring melt into the unrequisite sprue, sprue runner and riser after all. Thus, this
process is deemed very irrational. So, pouring yield represented as a ratio of the
weight of product portion to the total pouring weight can be dramatically improved
if only the product portion or the intended needful cavity portions such as the riser
and product portion is filled with the melt in one way or another, consequently to
solidify the melt in only the needful portions and, what is more, to enable significant
simplification of the subsequent processes such as of mold dissection and product
removal.
[0008] Although an investigation for prior art was conducted about a casting method in which
gravity pouring of melt is carried out from the upper mold part or lateral part of
a gas permeable mold, there could be found no prior art disclosing a casting method
in which only the intended cavity portion of the casting mold cavities is filled with
the melt.
[0009] As the casting method capable of filling only the intended cavity portion as described
above, a vacuum casting method is deemed as the most potential casting method. Thus,
the following Patent references 1 to 15 are enumerated as the prior art examples.
However, all these patent references are concerned with a type of filling the melt
into all the sprue, sprue runner, riser and product portion.
[0010] Patent Reference 1 (Japanese Published Unexamined Application
SHO 61-180642A) discloses a vacuum casting method, which comprises disposing an air-permeable casting
mold in a chamber and after closing a sprue with dissoluble material, and decompressing
the chamber to a prescribed pressure to pour melt into the chamber.
[0011] Patent Reference 2 (Japanese Published Unexamined Application
HEI 7-265998A) discloses a casting mold for vacuum casting, which has different mold thicknesses
in a product cavity and gating cavity in a normal temperature curing type casting
mold.
[0012] Patent Reference 3 (Japanese Published Unexamined Application No.
2003-170226A) discloses a vacuum casting method using a mold destined for entirely reducing the
pressure, which incorporates a sensor so as to initiate a decompressing action in
the mold after detecting pouring of melt into the mold by the sensor.
[0013] Patent Reference 4 (Japanese Published Unexamined Application
HEI 3-216258A) discloses a decompression device in which the whole peripheral surface of a casting
mold is airtightly covered with a sheet of resin film, and an exhaust port is disposed
in a portion thoroughly distant from a sprue to reduce the pressure.
[0014] Patent Reference 5 (Japanese Published Unexamined Application
SHO 60-124438A) discloses a vacuum casting method for performing pouring of melt after decompression
in the suction box, in which a plaster casting mold formed by flaskless molding is
placed on a suction box having ventholes and covered with a film sheet.
[0015] Patent Reference 6 (Japanese Published Examined Application
HEI 7-115119B) discloses a vacuum casting method, in which a flask having upper and lower openings
is provided within its lateral wall with a suction mechanism, and airtight sheets
are attached to the upper and lower faces of the flask to perform aspiration for decompression
in evaporative pattern casting.
[0016] Patent Reference 7 (Japanese Published Unexamined Application
HEI 6-122060A) discloses a vacuum casting method for performing pouring under a decompressed state,
in which a casting mold of organic caking additive is formed to a casting mold having
ventholes and set within an open-topped chamber made of steel plate.
[0017] Patent Reference 8 (Japanese Published Unexamined Application
HEI 8-10386A) discloses a vacuum casting method for performing pouring under a decompressed state,
in which a sand mold is embedded in casting sand within an open-topped vacuum container.
[0018] Patent Reference 9 (Japanese Published Unexamined Application
SHO 57-31463A) discloses a method for manufacturing a thin-thickness casting, in which the cavity
is aspirated to pour melt thereinto through a venthole formed at the position most
distant from a sprue of a mold.
[0019] Patent Reference 10 (Japanese Published Unexamined Application
HEI 6-55255A) discloses a casting method for manufacturing a steel casting, in which casting is
performed using a casting mold provided with a riser or an overflow at a position
distant from an ingate, while decompressing by means of a hole formed in its vicinity
in communication with the outside.
[0020] Also, the same Patent Reference 10 further discloses a method in which the pressure
is reduced so as to make the rate of pouring melt constant by decompression-rate controlling
means, and a method in which a mold level sensor is set in the ingate so as to start
decompression immediately after detecting the melt.
[0021] Patent Reference 11 (Japanese Published Unexamined Application
HEI 6-226423A) discloses a method for manufacturing a thin-thickness casting, in which an aspiration
member having larger air permeability than a casting mold is disposed between a vacuum
port and a riser or an overflow so as to make the degree of decompression in the cavity
on the side of the vacuum port than that in the cavity on the side of sprue, similarly
to the structure of the aforementioned Patent Reference 10.
[0022] Patent Reference 12 (Japanese Published Unexamined Application
HEI 9-85421A) discloses a vacuum casting method in which decompression is performed through a
hole communicating with the outside is formed in a core print set in a casting mold.
[0023] Patent Reference 13 (Japanese Published Unexamined Application
HEI 9-85421A) discloses a casting mold for vacuum casting, which is provided with an aspirating
guide for forming a passage between a portion to be decompressed in a internal space
of a casting mold and the outside of the casting mold.
[0024] Patent Reference 14 (Japanese Published Unexamined Application
SHO 60-56439A) discloses a plaster casting mold for vacuum casting, in which a filter of fire-resisting
material having higher permeability compared with plaster is prepared from the vicinity
of a final filling portion of the plaster casting mold to the outer surface thereof.
[0025] Patent Reference 15 (Japanese Published Examined Application
HEI 7-41400B) discloses a vacuum casting method in which gas produced from a green sand mold and
gas produced from a core are individually absorbed, and suction pressures are respectively
adjustable freely.
[0026] To sum up the matter, all the conventional vacuum casting methods described in the
foregoing patent references are featured in that the cavities in the casting mold
are filled with melt. Therefore, the conventional vacuum casting methods are low in
pouring yield, which is represented as a ratio of the weight of product portion to
the total pouring weight, and make post-processes such as mold dissection and product
removal cumbersome and complicated.
[0027] As stated above, none of the conventional art references describes or suggests a
casting method capable of filling only an intended cavity in a casting mold with melt.
[0028]
Patent Reference 1: |
Japanese Published Unexamined Application SHO 61-180642A |
Patent Reference 2: |
Japanese Published Unexamined Application HEI 7-265998A |
Patent Reference 3: |
Japanese Published Unexamined Application No. 2003-170226A |
Patent Reference 4: |
Japanese Published Unexamined Application HEI 3-216258A |
Patent Reference 5: |
Japanese Published Unexamined Application SHO 60-124438A |
Patent Reference 6: |
Japanese Published Examined Application HEI 7-115119B |
Patent Reference 7: |
Japanese Published Unexamined Application HEI 6-122060A |
Patent Reference 8: |
Japanese Published Unexamined Application HEI 8-10386A |
Patent Reference 9: |
Japanese Published Unexamined Application SHO 57-31463A |
Patent Reference 10: |
Japanese Published Unexamined Application HEI 6-55255A |
Patent Reference 11: |
Japanese Published Unexamined Application HEI 6-226423A |
Patent Reference 12: |
Japanese Published Unexamined Application HEI 9-85421A |
Patent Reference 13: |
Japanese Published Unexamined Application HEI 9-85421A |
Patent Reference 14: |
Japanese Published Unexamined Application SHO 60-56439A |
Patent Reference 15: |
Japanese Published Examined Application HEI 7-41400B |
Non-patent Reference: |
None |
DISCLOSURE OF INVENTION
PROBLEMS TO BE SOLVED BY THE INVENTION
[0029] In the light of the conventional art described above, the present invention was made
to provide a casting method capable of filling only an intended cavity portion of
mold cavities. According to the invention, the casting method can fulfill extremely
high pouring yield and considerably simplify a post-process after mold dissection.
MEANS OF SOLVING THE PROBLEMS
(Means 1)
[0030] A casting method for pouring melt having the weight volume ratio γ into a gas permeable
mold, characterized by filling an intended cavity portion with the melt with supply
of a compressed gas from a sprue and solidifying the melt after initiation of pouring
of the melt having the volume substantially equal to that of the cavity portion intended
to be filled with the melt in a cavity of the gas permeable mold.
[0031] The cavities of the casting mold in the present means should be constructed to comprise
a sprue, a sprue runner and a product portion for ease of explanation. And, an intended
cavity portion to be filled with melt is the product portion.
[0032] First, the melt equal in volume to the product portion which is the intended cavity
portion to be filled with the melt is poured into the product portion of the cavities
of the gas permeable mold. The melt is poured into the mold through the sprue to partially
fill the sprue runner and product portion with the melt. If remain untouched, the
melt is dispersed into the respective cavities, so that the surfaces of the melts
dispersed into the cavities become on the same level. Consequently, only the product
portion of the intended cavity portion, which is designed to be filled with the melt
in the present invention, cannot be filled with the melt.
[0033] With that in mind, in the first means according to the invention, a compressed gas
is supplied from a sprue at an appropriate time after initiation of pouring of the
melt to force the melt into the product portion with the pressure of the compressed
gas, and then, the melt with which the product portion of the intended cavity portion
is solidified. Since the melt is substantially equal in volume to the product portion
of the intended cavity portion, only the product portion of the intended cavity portion
can be filled with the melt.
[0034] In order to supply the melt having the volume substantially equal to that of the
intended cavity portion, the melt may be measured in parts with respect to each casting
mold by using a small ladle, or poured while being measured in one operation for one
casting shot by using a large ladle. The substantially equal volume referred to here
means the volume determined in view of suitable safety factor in consideration of
uplift of an upper mold, which is caused in pouring the melt, and thermal expansion
of the casting mold cavity.
[0035] As the compressed gas, a compressed air is generally easy-to-use and low cost. A
compressed inactive nitrogen gas comes in useful in the sense of inhibiting oxidation
of the melt.
[0036] When supplying the compressed gas, it is rather effective to prevent the compressed
gas from leaking from the sprue by closing the sprue with a flange or the like of
an air supply pipe in order to improve the operation of injecting the melt. Since
leakage of the compressed gas from the outer periphery of the casting mold diminishes
the operation of filling the intended cavity with the melt, it is desirable to take
any measures to prevent the leakage of the compressed gas therefrom, if possible.
Of course, it is not always necessary to take measures to prevent the leakage of the
compressed gas when the casting mold is low in air permeability or covered entirely
or partially with an airtight container or flask.
[0037] The appropriate time after initiation of pouring of the melt, at which the compressed
gas is supplied from the sprue, is preferably determined as the earliest possible
time during or after the course of passing of the aftermost melt through the sprue
while pouring the melt. Because the filled melt begins to solidify when delaying the
air supply, it is disadvantageously liable to develop defects such as cold shut and
misrun or origination of oxide.
[0038] Solidifying of the filled melt does not necessarily imply that the melt filled into
the casting mold solidifies entirely. Since outflow of the melt from a part of the
intended cavity portion is caused from the vicinity of the boundary between the intended
cavity portion filled with the melt and the other cavity portion, it is only necessary
to solidify at least the melt stagnated around the boundary vicinity. Besides, there
is no need to completely solidify the melt therearound, but the filled melt just has
to be solidified so as to crystallize into a solid phase to the extend of preventing
flowing of the filled melt out of the intended cavity portion. The details will be
described below with reference to Embodiment 1.
(Means 2)
[0039] There is provided a casting method based on Means 1, which is characterized by supplying
the compressed gas from the sprue to fill the intended cavity portion with the melt
and solidifying the melt while maintaining the supply of the compressed gas.
[0040] This Means based on Means 1, in which the intended cavity portion is filled with
the melt by using the compressed gas, resulting in solidifying the melt within the
cavity portion, is featured in that the compressed gas is continuously supplied after
filling the intended cavity portion with the melt to assure solidification of the
melt. By continuing the supply of the compressed gas, it is possible to prevent the
melt filled in the intended cavity portion with the supply of the compressed gas from
flowing back from the vicinity of the boundary between the intended cavity portion
and the other cavity portion and cause the melt in the boundary vicinity to solidify
swiftly by the cooling action of the compressed gas. The details will be described
below with reference to Embodiment 2.
(Means 3)
[0041] There is provided a casting method based on Means 1 or Means 2, which is characterized
in that the applied pressure of the compressed gas is no less than the melt static
pressure γH determined by the height H from a cavity inlet for introducing the melt
into the intended cavity portion to the uppermost of the intended cavity portion.
[0042] The casting method in which the product portion and riser are specified as the intended
cavity portion to be filled with the melt in the case where the mold cavity comprises
the sprue, sprue runner, riser and product portion, will be described. In order to
prevent, more surely, the melt filled in the intended cavity portion from flowing
out from the boundary vicinity toward the sprue runner, the applied pressure of the
compressed gas should be defined to no less than the melt static pressure γH determined
by the height H from a cavity inlet for introducing the melt into the intended cavity
portion to the uppermost of the intended cavity portion, where γ is the weight volume
ratio (kgf/cm
3) of the melt, H is the aforesaid height (cm), and thus, γH is the pressure (kgf/cm
2).
[0043] The melt static pressure γH means a hydrodynamical melt static pressure under which
the melt filled in the intended cavity portion is apt to flow out toward the sprue
runner. Thus, it becomes possible to prevent the melt from flowing out by maintaining
the applied pressure of the compressed gas thereabove.
[0044] The applied pressure of the compressed gas does not mean the pressure of the compressed
gas and should be so designed that the pressure in the other cavity portion (cavity
portions not yet filled with the melt) than the intended cavity portion becomes no
less than the melt static pressure γH. The details will be described below with reference
to Embodiment 3.
(Means 4)
[0045] There is provided a casting method based on Means 1 to 3, which is characterized
in that the intended cavity portion is filled with the melt with supply of the compressed
gas from the sprue, and there is used interrupting means for preventing the filled
melt from flowing back from the vicinity of the boundary between the intended cavity
portion and the other cavity portion.
[0046] The casting method makes use of the interrupting means for preventing the melt filled
in the intended cavity portion from flowing back from the boundary vicinity. The details
will be described below with reference to Embodiments 4 to 8.
(Means 5)
[0047] There is provided a casting method based on Means 4, which is characterized by using
means for cooling the boundary vicinity as the interrupting means so as to prevent
the melt filled therein from flowing back.
[0048] According to the casting method of this Means, solidification of the melt filled
in the intended cavity portion can be accelerated to surely prevent the filled melt
from flowing out toward the sprue runner by cooling the portion in the boundary vicinity.
Although the applied pressure of the compressed gas is used for preventing the filled
melt from flowing out, the casting method according to this Means can accelerate solidification
of the melt filled in the intended cavity portion by flowing gas. Specifically, it
is most effective to swiftly solidify the melt filled in the vicinity of the boundary
between the intended cavity portion and the other cavity portion by the flow of gas.
The compressed air is useful as the gas used here because it is significantly easy
to use and low cost. Any safe gases can be used. Low-temperature gas is effective
for expediting cooling. The details will be described below with reference to Embodiments
4 and 5.
(Means 6)
[0049] There is provided a casting method based on Means 4, which is characterized by using
means for mechanically blocking the boundary vicinity as the interrupting means so
as to prevent the melt filled therein from flowing back.
[0050] In the casting method of this Means, the boundary vicinity of the intended cavity
portion filled with the melt and the other cavity portion are blocked. As the means
for blocking the passage of the melt, a mold piece such as a shell mold having a shape
coincident with the shape of the boundary vicinity may be pressed onto the boundary
vicinity, or a blocking plate may be thrust into the mold in the boundary vicinity,
by way of example. The details will be described below with reference to Embodiment
8.
(Means 7)
[0051] There is provided a casting method based on Means 1-6, which is characterized by
decompressing the intended cavity portion to be filled with the melt before pouring
the melt or after initiation of pouring of the melt.
[0052] In the casting method of this Means, in order to facilitating the filling of the
melt into the intended cavity portion, the intended cavity portion to be filled with
the melt is decompressed before pouring the melt or after initiation of pouring of
the melt. By decompressed before pouring the melt, the poured melt can swiftly be
introduced into the intended cavity portion, thereby to simplify control of timing
of supplying the compressed gas and the pressure of the compressed gas after initiation
of pouring of the melt. Besides, the decompression after initiation of pouring of
the melt is not different in function and effect from that before pouring of the melt.
[0053] The difference between effects of decompression before pouring of the melt and after
initiation of pouring of the melt is that the decompression before pouring of the
melt can obtain a stable degree of decompression before filling the casting mold with
the melt, but the degree of decompression changes with pouring the melt. The decompression
after initiation of pouring of the melt brings about stable flow of the melt early
in the course of pouring the melt because the initiation of pouring of the melt is
commenced in a condition of atmosphere pressure, but a sufficient degree of decompression
may not be obtained in the course of filling the cavity with the melt if the timing
of commencing the decompression is delayed. The decompression before or after pouring
of the melt, whichever is appropriate, may be applied in accordance with the quality
of the melt and the shape of the mold cavity.
[0054] Although the whole casting mold may be decompressed, it is only necessary to decompress
at least the intended cavity portion. The reduced pressure is maintained after filling
the intended cavity portion with the melt. The details thereof will be described with
reference to Embodiments 9 and 10.
(Means 8)
[0055] The casting method in either Means 1 or Means 6 is characterized in that, before
pouring the melt or after initiation of pouring of the melt, the degree of decompression
in the intended cavity portion to be filled with the melt is determined to a decompressed
state of a pressure no less than the absolute value of the melt static pressure γH
determined by the height H from a cavity inlet for introducing the melt into the intended
cavity portion to the uppermost of the intended cavity portion.
[0056] In this Means, the degree of decompression in the intended cavity portion to be filled
with the melt before pouring the melt or after initiation of pouring of the melt is
put into the decompressed state of a pressure no less than the absolute value of the
melt static pressure γH. Hence, the intended cavity portion is filled with the melt
up to the uppermost thereof even without supplying with compressed gas in pouring
melt into the cavity, but the melt does not flow out from the boundary vicinity even
after filling the cavity with the melt. Thus, the compressed gas supplied after initiation
of pouring of the melt principally has a subsidiary effect of spill prevention by
pressure and a cooling effect by gas current, thus to improve the collective stability
in casting process. The decompression is maintained according to need even after filling
the intended cavity with the melt. The details will be described below with reference
to Embodiment 9.
(Means 9)
[0057] There is provided a casting method based on Means 1-6, which is characterized in
that the degree of decompression in the intended cavity portion to be filled with
the melt is determined before pouring the melt or after initiation of pouring of the
melt so as to bring the intended cavity portion into a decompressed state of a pressure
less than the absolute value of the melt static pressure γH determined by the height
H from a cavity inlet for introducing the melt into the intended cavity portion to
the uppermost of the intended cavity portion.
[0058] In this Means, the intended cavity portion is brought into a decompressed state in
that the degree of decompression in the intended cavity portion is set to a pressure
less than the absolute value of the melt static pressure γH. This is because inconvenience
such as seizing of sand and turbulent flow of the melt may possibly be caused by the
decompression, depending on the material of the melt and the shape of the casting
mold cavity, when the degree of decompression is increased to not less than the absolute
value of γH. In such a case, the degree of decompression should be made lower than
the absolute value of γH (weak decompression) as proposed in this Means, so that the
melt is gently introduced into the intended cavity portion and the seizing of sand
is not caused by the complex effect of the decompression and pressurization of the
compressed gas. The reduced pressure is maintained according to need after filling
the intended cavity portion with the melt. The details thereof will be described with
reference to Embodiment 10.
EFFECT OF THE INVENTION
[0059] The present invention achieves the following effects, which are beneficial compared
with the conventional casting method.
[0060] To be more specific, in any conventional casting method, all parts of the mold cavity
are filled with the melt, consequently to reduce the pouring yield represented as
a ratio of the weight of product portion to the total pouring weight. On the other
hand, according to the present invention, only the necessary part of the cavity portion
can be filled with the melt to be solidified, thus to dramatically improve the pouring
yield. As a result, the melt required for forming a casting product can be spared
considerably.
[0061] Since only the intended cavity portion is filled with the melt, only a molded part
formed by solidifying the melt may be taken out from the cavity and processed upon
mold dissection, consequently to considerably curtail the work operation in post-processing.
[0062] What it comes down to is that the following effects can be achieved by the present
invention. (1) The considerable improvement in pouring yield enables reduction in
melt usage, thus to reduce the energy and cost required for melting. (2) The work-hour
in mold dissection can be remarkably reduced. These effects (1) and (2) make substantial
contribution to CO
2 reduction, which is getting widespread international attention.
BEST MODE FOR CARRYING OUT THE INVENTION
[0063] The present invention can be put into practice by any of the aforementioned Means
1 through Means 9, but as the best mode for carrying out the invention, there can
be exemplified a casting method based on the aforementioned Means 7, in which the
melt approximately equal in volume to the intended cavity portion in the state of
decompressing the intended cavity portion to be filled with the melt before pouring
the melt or after initiation of pouring of the melt. The degree of decompression and
the pressure of the compressed gas are determined in consideration of the quality
of the melt, the shape of the casting cavity and the casting method.
[0064] Although the present invention will be described with reference to the following
embodiment, it is not to be considered limited to what is described in the specification.
[EMBODIMENT 1]
[0065] Embodiment 1 is illustrated in FIG 1 and FIG 2. In this embodiment carried out by
the aforementioned Means 1, after initiation of pouring of the melt substantially
equal in volume to the cavity portion intended to be filled with the melt in a cavity
of the gas permeable mold, the intended cavity portion is filled with the melt while
supplying a compressed gas from a sprue to solidify the melt.
[0066] First, the structure of a casting mold 1 will be explained. The casting mold 1 is
a sand mold and formed of an upper mold flask 2 and a lower mold flask 3, which are
placed on a mold stool 4 in the state of being superposed one on another to form a
mold cavity therebetween. The mold cavity 7 includes a sprue 8, a sprue runner 9,
and a product portion 11. In general, a riser is likely to be formed between the sprue
runner 9 and product portion 11, but the casting mold in this embodiment has no riser.
[0067] In the casting method in this embodiment, which will be described here, the melt
is introduced into only the product portion 11 as the intended cavity portion 12 within
the mold cavity 7 and solidified therein. FIG 1 illustrates the state in that the
melt having the volume substantially equal to that of the cavity portion 12 intended
to be filled with the melt is poured into the casting mold 1 by using a pouring ladle
13. As the melt 30 poured in the casting mold is approximately equal in volume to
the product portion 11, the whole cavity cannot entirely be filled with the melt in
such a manner that part of the melt is introduced into the product portion 11 and
another part of the melt is stagnated in the sprue runner 9. Besides, there is seldom
the melt head of the sprue 8, so that a force for inpouring the poured melt 30 into
the product portion 11 is extremely small. As a result, if nothing is done, the product
portion 11 cannot fully be filled with the poured melt 30 or long time is required,
resulting in product failure.
[0068] With that in mind, as illustrated in FIG 2, the compressed gas 16 made by a compression
device 15 is supplied from the upper portion of the sprue 8, so that the melt 30 stagnated
in the sprue runner 9 can be injected into the product portion 11 by the pressure
of the compressed gas. In this embodiment, as the compressed gas, compressed air having
pressure of 5 kgf/cm
2 and an air volume of 60 l/sec is used. There is attached a seal member 17 to a portion
to which the compressed gas 16 is supplied in order to prevent gas leakage. Since
the quantity of the poured melt is substantially equal to the volume of the product
portion, only the product portion 11 as the intended cavity portion 12 comes eventually
to be filled with the melt 30. Then, the poured melt 30 is solidified in this state.
[0069] The timing for supplying the compressed gas 16 does not always have to wait for the
melt to stagnate in the sprue runner 9 as touched upon above. FIG 1 illustrates the
state in which the melt stagnates to account for the principle of the present invention,
but does not show the preferred embodiment of the invention. Namely, the melt falls
in temperature with increasing its stagnating time in the sprue runner, consequently
to increase probability of causing defects such as cold shut, misrun and emergence
of oxides. Therefore, it is advised to supply the compressed gas during or right after
passage of the aftermost melt through the sprue 8 upon starting of pouring of the
melt, so that the melt can be smoothly injected into the intended cavity portion 12
without causing stagnation of the melt in the sprue runner 9. This is a practical
use for the embodiment. As to the timing for supplying the compressed gas, the same
holds for the following embodiments.
[0070] In the manner described above, the melt could be injected into only the product portion
which is a part of the intended cavity portion within the mold cavity, thus to be
solidified. Since the product portion in this embodiment is formed in the lower mold
part of the casting mold, it may be as well to halt supply of the compressed gas supply
or slightly supply the compressed gas to expedite solidification of the melt.
[0071] The term "solidification" is broadly interpreted as a phenomenon of solidifying the
melt in the whole product portion, which is the intended cavity portion in the mold
cavity, but narrowly means that the melt is solidified in the vicinity of the boundary
between the intended cavity portion and the other cavity portion without allowing
the filled melt to flow out toward the sprue runner 9. To be specific, the narrowly-defined
solidification means that the melt in the boundary vicinity is solidified until losing
fluidity due to solid phase crystallization of the melt. That is, the present invention
aims at introducing the melt into only the intended cavity portion and solidifying
the melt there, but it is only necessary to carry on the injection and solidification
of the melt in various manners until the melt solidifies in the narrow sense of the
meaning. The same is true on the following embodiments.
[0072] When the compressed gas is supplied, the gas partially escapes through between the
particles forming the casting mold having gas permeability, thus to reduce the activity
of injecting the melt into the cavity. With this point in view, the pressure and gas
volume of the compressed gas may be adequately regulated to ensure a sufficient action
of injecting the melt. Alternatively, it is effective to seal the casting mold with
impervious material according to need.
[0073] In general, a compressed air as the compressed gas is most easy-to-use and low cost.
Instead, inert gases such as compressed nitrogen can effectively be used. The pressure
and gas volume of the compressed gas are determined in consideration of gas permeability
of the casting mold, the shape of the mold flask, the overall sealing degree of the
mold, casting design and so on.
[0074] In the conventional casting method, the melt is poured into the entire cavity in
the casting mold. However, the casting method according to the present invention makes
it possible to inject the melt into only the intended cavity portion, so that the
injected melt is solidified in the intended cavity portion. As a result, pouring yield
represented as a ratio of the weight of product portion to the total pouring weight
can be dramatically improved. As an example, the pouring yield, which was about 50%
to 70% at the most according to the conventional casting method, can be improved to
about 100%, consequently to save on the melt significantly.
[0075] According to this embodiment of the invention, the melt is fed into only the product
portion in the cavity, but does not exist in the sprue 8 and sprue runner 9. Thus,
all that is left is a simple operation of taking out a resultant molded part formed
by solidifying the melt injected into only the product portion, consequently to substantially
lighten the work load.
[EMBODIMENT 2]
[0076] Embodiment 2 is illustrated in FIG 3 and FIG 4. In this embodiment carried out by
the aforementioned Means 2, the melt is injected into the intended cavity portion
by supplying the compressed gas after initiation of pouring of the melt and solidified
with maintenance of supplying the compressed gas.
[0077] FIG 3 illustrates the state after the melt 30 is poured into the product portion
11 as the intended cavity portion 12. The structure formed of the casting mold 1 and
mold cavity 7 is identical to that in Embodiment 1 except that a cover member 18 made
of iron is disposed on the upper mold flask 2 to secure airtightness. The cover member
18 is provided to enhance the efficiency of the pressure of the compressed gas. It
is desirable to make the cover member 18 of impervious material, but the equivalent
effect can be achieved even by using the cover member made of a material lower in
gas permeability than the casting mold.
[0078] In the state after pouring the melt as illustrated in FIG 3, the volume of the poured
melt is substantially equal to that of the product portion 11 similarly to Embodiment
1, besides, there is seldom the melt head of the sprue 8, thus a part of the melt
30 is introduced into the product portion 11 and another part of the melt to stagnate
in the sprue runner 9.
[0079] Next, as the compressed gas 16 made by the compression device 15 is supplied from
the upper portion of the sprue 8 as shown in FIG 4, the melt 30 in the sprue runner
6 is injected into the product portion 11 by the action of the compressed gas 16 similarly
to Embodiment 1. The upper portion of the upper mold flask 2 is covered with the cover
member 18 to secure airtightness in this embodiment, consequently to diminish leakage
of the compressed gas 16 from the casting mold 1. Consequently, the compressed gas
serves to make an action to inject the melt into the product portion 11 with higher
efficiency than in Embodiment 1. In this embodiment, as the compressed gas, compressed
air having pressure of 5 kgf/cm
2 and an air volume of 601/sec was used.
[0080] The supplying of the compressed gas 16 is retained to impart moderate pressure after
injecting the melt 30 into the product portion 11, so that the injected melt 30 can
be solidified without causing the melt to flow out from the product portion 11. The
pressure and gas volume of the compressed gas 16 are adequately determined in accordance
with the type of the casting mold, the casting design and so forth.
[0081] This embodiment makes it possible to inject the melt into the intended cavity portion
and solidify the injected melt more stably than Embodiment 1.
[0082] As stated in Embodiment 1, the timing for supplying the compressed gas does not always
have to wait for the melt to stagnate in the sprue runner. It is a practical embodiment
that the compressed gas is supplied swiftly during or after the course of passing
of the aftermost melt through the sprue to smoothly inject the melt into the intended
cavity portion without causing stagnation of the melt in the sprue runner.
[EMBODIMENT 3]
[0083] Embodiment 3 is illustrated in FIG 5 and FIG 6. In this embodiment carried out by
the aforementioned Means 3, a part of the intended cavity portion having a certain
height, which is formed in the upper mold part, is filled with the melt by supplying
specifically-defined pressure of the compressed gas to be solidified there.
[0084] As shown in FIG 5, the casting mold 1 has the substantially same in structure as
that in Embodiment 2, and the mold cavity 7 comprises the sprue 8, sprue runner 9,
riser 10 and product portion 11. The product portion 11 is formed within an upper
mold 5 and a lower mold 6, and the part of the product portion 11 in the upper mold
has a height H. In this embodiment, the intended cavity portion 12 formed of the product
portion 11 and riser 10 is filled with the melt to be solidified there. The aforementioned
height H is equivalent to a height from a cavity inlet from which the melt inflows
into the intended cavity portion.
[0085] FIG 5 shows the state after pouring the melt 30 substantially equal in volume to
the intended cavity portion 12. Similarly to Embodiments 1 and 2, the volume of the
melt poured is substantially equal to that of the intended cavity portion, and besides,
there is seldom the melt head of the sprue 8. That is, the melt 30 is partially filled
in the whole cavity, falling on horizontal level.
[0086] As shown in FIG 6, the melt 30 is injected into the intended cavity portion 12 while
supplying the compressed gas 16 from the upper portion of the sprue 8 similarly to
Embodiments 1 and 2, and then, the melt 30 is solidified while supplying the compressed
gas 16. In this embodiment, the applied pressure of the compressed gas 16 is determined
to not less than γH where γ is a weight volume ratio (kgf/cm
3) of the melt, and H is a height (cm) from a cavity inlet from which the melt inflows
into the intended cavity portion to the uppermost part of the intended cavity portion
12. Hence, γH is a pressure (kgf/cm
2). For instance, when cast-iron melt having a weight volume ratio of γ=7×10
-3 kgf/cm
3 is injected into a casting mold cavity of H=20 cm, the equation "γH=0.14kgf/cm
2" is satisfied.
[0087] The value γH has a meaning of a melt static pressure by which the melt 30 filled
in the intended cavity portion 12 attempts to flow out from the boundary vicinity
19 between the intended cavity portion 12 and the other cavity portion 20 toward the
sprue runner 9. Therefore, the melt 30 can be injected into the intended cavity portion
12 up to the uppermost of the intended cavity portion by the action of the applied
pressure not less than γH of the compressed gas 16. By maintaining the applied pressure
of the compressed gas, the melt 30 filled in the cavity portion can be stopped flowing
out. Incidentally, the applied pressure not less than γH does not mean the pressure
of the compressed gas, but has a meaning that the pressure in the boundary vicinity
19 is kept not less than γH in consideration of leakage of the compressed gas 16 from
the casting mold 1.
[0088] As shown in this embodiment, even when the intended cavity portion 12 to be filled
with the melt is placed high above the cavity inlet of the melt, the melt 30 is injected
into the intended cavity portion 12 by supplying the compressed gas 16, which has
the applied pressure of not less than the melt static pressure γH determined by the
weight volume ratio γ of the melt and the height H from a cavity inlet for introducing
the melt into the intended cavity portion to the uppermost of the intended cavity
portion, and maintaining the applied pressure of the compressed gas, so that a desired
casting product can be obtained from the melt injected into only the product portion
11 and the riser 10 of the intended cavity portion 12.
[0089] As stated in Embodiments 1 and 2, the timing for supplying the compressed gas does
not always have to wait for the melt to stagnate in the sprue runner as shown in FIG
5. It is a practical embodiment that the compressed gas is supplied swiftly during
or after the course of passing of the aftermost melt through the sprue to smoothly
inject the melt into the intended cavity portion without causing stagnation of the
melt in the sprue runner.
[EMBODIMENT 4]
[0090] Embodiment 4 is illustrated in FIG 7. In this embodiment carried out by the aforementioned
Means 4 and Means 5, the melt is injected into the intended cavity portion by supplying
the compressed gas from the sprue after initiation of pouring of the melt and cooling
the vicinity of the boundary between the intended cavity portion and the other cavity
portion to solidify the melt.
[0091] FIG 7 illustrates the state of supplying the compressed gas 16 from the upper part
of the sprue 8 after pouring the melt having the volume substantially equal to that
of the intended cavity portion 12. With supply of the compressed gas 16, the melt
30 is injected into the product portion 11 and the riser 10 of the intended cavity
portion 12. The structure formed of the casting mold 1 is approximately equal to that
in Embodiment 3 except that a venting hole 21 formed in the upper part of the boundary
vicinity 19 between the intended cavity portion 12 and the other cavity portion 20.
[0092] The function of this embodiment will be explained on the basis of this structure.
The melt 30 is injected into the intended cavity portion 12 with supply of the compressed
gas 16 after initiation of pouring of the melt, and then, by continuing the supply
of the compressed gas 16, the compressed gas flows through the venting hole 21 for
allowing the gas to pass through most easily, while conducting heat away from the
boundary vicinity 19 to cool the boundary vicinity. Consequently, the boundary vicinity
19 is rapidly cooled to solidify the melt, thus to shorten the amount of time required
for supplying the compressed gas 16. That is, the compressed gas 16 is used for having
an effect for injecting the melt 30 and a cooling effect.
[0093] Meanwhile, if the venting hole 21 is not formed, the compressed gas 16 is allowed
to escape through between the particles forming the casting mold by maintaining the
applied pressure of the compressed gas, and therefore, the boundary vicinity 19 is
cooled at a certain speed. However, this embodiment has higher cooling capacity to
solidify the melt promptly.
[0094] As stated above, the time to maintain the supply of the compressed gas after injecting
the melt into the intended cavity portion can be shortened by providing the venting
hole for cooling the boundary vicinity with the compressed gas, thus to solidify the
melt promptly. Consequently, the production efficiency can be enhanced when applying
the present invention to an actual production line.
[EMBODIMENT 5]
[0095] Embodiment 5 is illustrated in FIG 8. In this embodiment carried out by the Means
4 and Means 5 similarly to Embodiment 4 as above, the melt is injected into the intended
cavity portion by supplying the compressed gas from the sprue after initiation of
pouring of the melt and cooling the vicinity of the boundary between the intended
cavity portion and the other cavity portion with the compressed gas to solidify the
melt.
[0096] FIG 8 illustrates the state of supplying the compressed gas 16 from the upper part
of the sprue 8 after pouring the melt 30 having the volume substantially equal to
that of the intended cavity portion 12. With supply of the compressed gas 16, the
melt 30 is injected into the product portion 11 and the riser 10 of the intended cavity
portion 12. The structure formed of the casting mold 1 is approximately equal to that
in Embodiment 4 except that a venting hole 21 formed in the upper part of the boundary
vicinity 19 between the intended cavity portion 12 and the other cavity portion 20.
In this embodiment, a gas supply pipe 22 is disposed separately from the sprue 8,
so that the compressed gas 16 can be supplied from the upper part of the venting hole
21. The gas supply pipe 22 is provided with a valve 23.
[0097] The function of this embodiment will be explained on the basis of this structure.
After injecting the melt 30 from the sprue 8 into the intended cavity portion 12 with
the compressed gas 16, the valve 23 of the gas supply pipe 22 disposed above the venting
hole 21 is open to supply the compressed gas 16 to the venting hole 21, thus to cool
the boundary vicinity 19 rapidly with both the supply of gas from the sprue 8 and
the supply of gas from the venting hole 21. As a result, similarly to Embodiment 4,
the amount of time required for supplying the compressed gas 16 can be shortened after
filling the intended cavity portion 12 with the melt 30, so that the production efficiency
can be enhanced when applying the present invention to an actual production line.
[EMBODIMENT 6]
[0098] Embodiment 6 is illustrated in FIG 9 and FIG 10. In this embodiment carried out by
the aforementioned Means 4 and Means 6, the intended cavity portion is filled with
the melt while supplying a compressed gas from a sprue, and the vicinity of the boundary
between the intended cavity portion and the other cavity portion is mechanically blocked.
[0099] FIG 9 illustrates the state in that the melt 30 having the volume substantially equal
to that of the intended cavity portion 12 is poured into the mold cavity. In this
embodiment, as shown in FIG 10, after pouring the melt, a mold piece 24 made of a
shell mold is put into the sprue 8, and then, the melt 30 is injected into the intended
cavity portion 12 with supplying the compressed gas 16 from the sprue 8, while thrusting
the mold piece 24 into the boundary vicinity 19. The boundary vicinity 19 conforms
in shape to the mold piece 24, thereby to prevent flowing out of the melt 30. The
part of melt 30 in contact with the mold piece 24 is solidified rapidly, so that the
time to maintain the compressed gas 16 can be shortened. Although the mold piece 24
formed of a sand mold such as a shell mold is easy-to-use and low cost, the mold piece
made of fire-resistant material being smaller in specific gravity than the melt can
achieve the same effect and function.
[0100] According to this embodiment, the melt can be solidified swiftly by obstructing the
passage of the filled melt, so that the production efficiency can be enhanced when
applying the present invention to an actual production line.
[EMBODIMENT 7]
[0101] Embodiment 7 is illustrated in FIG 11 and FIG 12. In this embodiment carried out
by the aforementioned Means 4 and Means 6, the intended cavity portion is filled with
the melt while supplying a compressed gas from a sprue, and the vicinity of the boundary
between the intended cavity portion and the other cavity portion is mechanically blocked.
[0102] FIG 11 illustrates the state immediately before the melt 14 having the volume substantially
equal to that of the intended cavity portion 12 is poured into the mold cavity. In
this embodiment, there is formed a concave portion 25 in the lower mold in the boundary
vicinity 19 of the mold cavity 7 so as to mount a blocking piece 26 of a shell mold
therein.
[0103] FIG 12 shows the state in which the melt 30 is injected into the intended cavity
portion 12 with supply of the compressed gas 16 after initiation of pouring of the
melt. When the melt 30 is filled in the cavity portion, the blocking piece 26 mounted
in the concave portion 25 floats with its buoyancy and comes in contact with the upper
wall of the sprue runner, consequently to obstruct the passage of the melt 30. Thus,
the blocking piece 26 serves to prevent flowing out of the melt 30 and expedite cooling
of the melt in the boundary vicinity 19 as a result of coming in contact with the
melt 30. Hence, since the time to supply the compressed gas 16 can be shortened, the
production efficiency can be enhanced when applying the present invention to an actual
production line.
[EMBODIMENT 8]
[0104] Embodiment 8 is illustrated in FIG 13. In this embodiment carried out by the aforementioned
Means 4 and Means 6, the intended cavity portion is filled with the melt while supplying
a compressed gas from a sprue, and the vicinity of the boundary between the intended
cavity portion and the other cavity portion is mechanically blocked.
[0105] FIG 13 shows the state in which the melt 30 is injected into the intended cavity
portion 12 with supply of the compressed gas 16 after initiation of pouring of the
melt 30 substantially equal in volume to the intended cavity portion 12. In this embodiment,
a venting hole 21 is formed in the upper part of the boundary vicinity 19, so that
a blocking plate 27 is plunged into the casting mold in the boundary vicinity 19 through
the venting hole 21, thus to block the melt 30. In this case, the venting hole 21
conforms in shape to the blocking plate 27.
[0106] This embodiment makes it possible to prevent flowing out of the melt 30 by directly
plunging the blocking plate 27 into the boundary vicinity 19 after injecting the melt
30, so that the need for waiting for solidification of the melt can be eliminated,
and therefore, the supply of the compressed gas 16 can be ceased immediately after
blocking. Consequently, the production efficiency can be enhanced when applying the
present invention to an actual production line.
[0107] The method for blocking in the boundary vicinity of Means 6 is illustrated in Embodiment
6 through 8 by way of example, but, in short, what that means is that the filled melt
is prevented from flowing out by using some suitable kind of blocking means. Any other
means can achieve the same effect and function.
[EMBODIMENT 9]
[0108] Embodiment 9 is illustrated in FIG 14 through FIG 16. In this embodiment carried
out by the aforementioned Means 7 and Means 8, the intended cavity portion is decompressed
to promptly fill the intended cavity portion with the poured melt before pouring the
melt or after initiation of pouring of the melt, and according to need, after pouring
the melt, the intended cavity portion is further decompressed while supplying the
compressed gas from the sprue.
[0109] FIG 14 illustrates the state immediately before the melt 14 having the volume substantially
equal to that of the intended cavity portion 12 is poured into the mold cavity. In
the casting mold 1, the venting hole 21 is formed respectively at the upper part of
the cavity of the product portion 11 and the riser 10 of the intended cavity portion
12. On the upper mold flask 2, there is disposed a decompression hood 29 in communication
with a decompression device 28. The venting hole 21 has a decompression action strongly
on the intended cavity portion 12, so that a desired degree of decompression can be
stably maintained. However, the venting hole is not necessarily indispensable in the
present invention, but it is only necessary to put the intended cavity portion to
a prescribed degree of decompression.
[0110] The degree of decompression of the intended cavity portion 12 is increased to not
less than the absolute value of γH by decreasing the pressure from the upper mold
5. In γH, γ is the weight volume ratio of the melt, and H is the height from a cavity
inlet for introducing the melt into the intended cavity portion to the uppermost of
the intended cavity portion. The height H is equivalent to the height of the upper
mold portion of the product portion 11 in this embodiment. γH is the melt static pressure
by which the melt 30 filled in the intended cavity portion 12 attempts to flow out
from the boundary vicinity.
[0111] FIG 15 illustrates the state after pouring the melt. The poured melt 30 is smoothly
injected to the uppermost of the intended cavity portion 12, since the intended cavity
portion 12 is decompressed to not less than γH. As the sprue 8 is open to the air
after initiation of pouring the melt, the degree of decompression changes. Thus, as
shown in FIG 16, it is possible to prevent flowing out of the poured melt, which is
injected from the upper part of the sprue 8 with supply of the compressed gas 16,
and rapidly cool the melt in the boundary vicinity 19 by the cooling action of the
compressed gas 16 to be solidified rapidly.
[0112] The decompression caused by the decompression device is continuously maintained until
solidifying the melt filled in the intended cavity portion according to need. That
is, the inside of the intended cavity portion is decompressed before pouring the melt
or after initiation of pouring of the melt so as to smoothly inject the melt into
the intended cavity portion, and then, the heat of the casting mold is effectively
dissipated to rapidly solidify the melt with maintaining the decompression in the
intended cavity portion, while preventing the poured melt from flowing out of the
boundary vicinity by the compressed gas.
[0113] The timing of commencing the decompression may be the time before pouring the melt
as performed in this embodiment or after initiation of pouring of the melt. Both the
timing can achieve the same function and effect. However, there is a difference in
change of the degree of decompression in the casting mold cavity between the timing
before pouring the melt and the timing after initiation of pouring of the melt. To
be specific, the decompression before pouring the melt enables the casting mold cavity
to be maintained at a stable degree of decompression before pouring the melt, but
the degree of decompression in the casting mold cavity changes as the melt is poured.
The decompression after initiation of pouring of the melt enables the stability of
the flowing of the melt in the early phase of pouring of the melt because the pouring
is carried out in atmospheric pressure, but there are cases where a ample degree of
decompression may not be assured in the process of pouring the melt when the timing
of commencing the decompression is delayed. The decompression before or after pouring
of the melt, whichever is appropriate, may be applied in accordance with the quality
of the melt and the shape of the mold cavity.
[0114] As is described above, by combining the decompression and the supply of the compressed
gas, the injection of the melt into the intended cavity portion can be more stably
carried out, thus to promptly solidify the melt.
[EMBODIMENT 10]
[0115] Embodiment 10 is illustrated in FIG 17 and FIG 18. In this embodiment carried out
by the aforementioned Means 7 and Means 9, the intended cavity portion is decompressed
at a low degree of decompression (weak decompression) to promptly fill the intended
cavity portion with the poured melt before pouring the melt or after initiation of
pouring of the melt, and according to need, after pouring the melt, the intended cavity
portion is further decompressed while supplying the compressed gas from the sprue.
[0116] FIG 17 illustrates the state immediately before the melt 14 having the volume substantially
equal to that of the intended cavity portion 12 is poured into the mold cavity. In
the embodiment, the casting mold has no venting hole. The intended cavity portion
12 in this embodiment is decompressed to a pressure less than the absolute value of
the melt static pressure γH (weak compression) before pouring the melt. The poured
melt 30 can be smoothly introduced into the intended cavity portion 12 thus decompressed.
However, as the degree of decompression is lower than the absolute value of γH, the
melt 30 cannot be introduced up to the uppermost of the intended cavity portion 12.
[0117] Therefore, as shown in FIG 18, the melt 30 is introduced up to the uppermost of the
intended cavity portion 12 by supplying the compressed gas 16 from the upper part
of the sprue 8. Thereafter, solidification of the melt in the boundary vicinity 19
is expedited in this state. The decompression may be maintained according to need.
To expedite solidification of the melt in the shortest possible time, it is preferable
to maintain or strengthen the decompression. The timing of commencing the decompression
may be the time before pouring the melt as performed in this embodiment or after initiation
of pouring of the melt.
[0118] The reason why the degree of decompression is less than the absolute value of γH
in this embodiment is because inconvenience such as turbulent flow of the melt and
emergence of the oxidization of the melt may possibly be caused by the decompression,
depending on the material of the melt and the shape of the casting mold cavity. In
such a case, there had better introduce the melt into the intended cavity portion
at a rather low degree of decompression as in this embodiment, filling the melt into
the intended cavity portion in tandem with the supplying action of the compressed
gas and solidifying the melt.
[0119] FIG 19 illustrates the state of pouring the melt when the intended cavity portion
to be filled with the melt includes the product portion, riser and sprue runner. The
processes of pouring the melt and decompressing and pressurizing the intended cavity
portion are the same as described above. The pouring yield in this case is decreased
as the quantity of the poured melt is increased, but this embodiment is superior in
that the melt can be injected infallibly into the critical portions in casting such
as the product portion or the combined product portion and riser, without concern
for weighing accuracy of the quantity of the melt to be poured. Since the casting
mold has no sprue, the pouring yield can be improved by about 10% to 15% in the case
of such a quantity of the poured melt.
[0120] In casting a plurality of castings with a single casting mold having the intended
cavity portions comprising only the product portions and risers as shown in FIGS.
17 and 18, it is necessary to dispense the pouring melt respectively to the plural
product portions and risers as uniform as possible. On the contrary, the casting mold
having the intended cavity portions comprising the product portions, risers and sprue
runners as shown in FIG 19 is superior in that the pouring melt can be injected into
the intended cavity portions without taking into consideration of the need for uniformly
dispensing the pouring melt into the intended cavity portions.
[0121] Thus, the intended cavity portion to be filled with the melt may be adequately designed
depending on the situation. For instance, the product portion, riser and a part of
sprue runner may be formed in the intended cavity portion. Further, in the case of
the casting mold having no riser, the product portion and a part of sprue runner may
be formed in the intended cavity portion. The same applies validly to all Embodiments
1 to 10.
[0122] Embodiments 9 and 10 in which decompression and supply of compressed gas are effected
in combination enables more stable injection and solidification of the melt relative
to the intended cavity portion.
BRIEF DESCRIPTION OF THE DRAWINGS
[0123]
FIG 1 is a view showing the state after pouring melt in Embodiment 1 of the present
invention.
FIG 2 is a view showing supply of compressed gas in Embodiment 1 of the present invention.
FIG 3 is a view showing the state after pouring the melt in Embodiment 2 of the present
invention.
FIG 4 is a view showing the supply of compressed gas in Embodiment 2 of the present
invention.
FIG 5 is a view showing the state after pouring the melt in Embodiment 3 of the present
invention.
FIG 6 is a view showing the supply of compressed gas in Embodiment 3 of the present
invention.
FIG 7 is a view showing Embodiment 4 of the present invention.
FIG 8 is a view showing Embodiment 5 of the present invention.
FIG 9 is a view showing the state after pouring the melt in Embodiment 6 of the present
invention.
FIG 10 is a view showing the supply of compressed gas in Embodiment 6 of the present
invention.
FIG 11 is a view showing the state before pouring the melt in Embodiment 7 of the
present invention.
FIG 12 is a view showing the state after pouring the melt in Embodiment 7 of the present
invention.
FIG 13 is a view showing Embodiment 8 of the present invention.
FIG 14 is a view showing the state before pouring the melt in Embodiment 9 of the
present invention.
FIG 15 is a view showing the state after pouring the melt in Embodiment 9 of the present
invention.
FIG 16 is a view showing the supply of compressed gas in Embodiment 9 of the present
invention.
FIG 17 is a view showing the state before pouring the melt in Embodiment 10 of the
present invention.
FIG 18 is a view showing the state after pouring the melt in Embodiment 10 of the
present invention.
FIG 19 is another view showing the state after pouring the melt in Embodiment 10 of
the present invention.
EXPLANATION OF REFERENCE NUMERALS
[0124]
- 1
- Casting mold
- 2
- Upper mold flask
- 3
- Lower mold flask
- 4
- Mold stool
- 5
- Upper mold
- 6
- Lower mold
- 7
- Mold cavity
- 8
- Sprue
- 9
- Sprue runner
- 10
- Riser
- 11
- Product portion
- 12
- Intended cavity portion
- 13
- Pouring ladle
- 14
- Melt
- 15
- Compression device
- 16
- Compressed gas
- 17
- Seal member
- 18
- Cover member
- 19
- Boundary vicinity
- 20
- Other cavity portion
- 21
- Venting hole
- 22
- Gas supply pipe
- 23
- Valve
- 24
- Mold piece
- 25
- Concave portion
- 26
- Blocking piece
- 27
- Blocking plate
- 28
- Decompression device
- 29
- Decompression hood
- 30
- Poured melt
- 31
- Packing member
- 32
- Resin foam plate