U.S. patent application number 14/781210 was filed with the patent office on 2016-02-25 for pulling-up-type continuous casting apparatus and pulling-up-type continuous casting method.
This patent application is currently assigned to TOYOTA JIDOSHA KABUSHIKI KAISHA. The applicant listed for this patent is Yusei KUSAKA, Naoaki SUGIURA. Invention is credited to Yusei KUSAKA, Naoaki SUGIURA.
Application Number | 20160052051 14/781210 |
Document ID | / |
Family ID | 51689036 |
Filed Date | 2016-02-25 |
United States Patent
Application |
20160052051 |
Kind Code |
A1 |
SUGIURA; Naoaki ; et
al. |
February 25, 2016 |
PULLING-UP-TYPE CONTINUOUS CASTING APPARATUS AND PULLING-UP-TYPE
CONTINUOUS CASTING METHOD
Abstract
A pulling-up-type continuous casting apparatus according to an
aspect of the present invention includes a holding furnace that
holds molten metal, a shape defining member disposed near a
molten-metal surface of the molten metal held in the holding
furnace, the shape defining member being configured to define a
cross-sectional shape of a cast-metal article to be cast as the
molten metal passes through the shape defining member, a first
nozzle that blows a cooling gas on the cast-metal article, the
cast-metal article being formed as the molten metal that has passed
through the shape defining member solidifies, and a second nozzle
that blows a gas toward the cast-metal article in an obliquely
upward direction from below a place on the cast-metal article on
which the cooling gas is blown from the first nozzle.
Inventors: |
SUGIURA; Naoaki;
(Takahama-shi, JP) ; KUSAKA; Yusei; (Toyota-shi,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SUGIURA; Naoaki
KUSAKA; Yusei |
|
|
US
US |
|
|
Assignee: |
TOYOTA JIDOSHA KABUSHIKI
KAISHA
Toyota-shi, Aichi
JP
|
Family ID: |
51689036 |
Appl. No.: |
14/781210 |
Filed: |
April 10, 2013 |
PCT Filed: |
April 10, 2013 |
PCT NO: |
PCT/JP2013/002453 |
371 Date: |
September 29, 2015 |
Current U.S.
Class: |
164/485 ;
164/444 |
Current CPC
Class: |
B22D 11/145 20130101;
B22D 11/141 20130101; B22D 11/01 20130101; B22D 11/1246 20130101;
B22D 11/041 20130101; B22D 11/08 20130101; B22D 11/124
20130101 |
International
Class: |
B22D 11/124 20060101
B22D011/124; B22D 11/14 20060101 B22D011/14; B22D 11/041 20060101
B22D011/041 |
Claims
1. A pulling-up-type continuous casting apparatus comprising: a
holding furnace that holds molten metal; a shape defining member
disposed near a molten-metal surface of the molten metal held in
the holding furnace, the shape defining member being configured to
define a cross-sectional shape of a cast-metal article to be cast
as the molten metal passes through the shape defining member; a
first nozzle that blows a cooling gas on the cast-metal article,
the cast-metal article being formed as the molten metal that has
passed through the shape defining member solidifies; and a second
nozzle that blows a gas toward the cast-metal article in an
obliquely upward direction from below a place on the cast-metal
article on which the cooling gas is blown from the first
nozzle.
2. The pulling-up-type continuous casting apparatus according to
claim 1, wherein the second nozzle is fixed on the shape defining
member.
3. The pulling-up-type continuous casting apparatus according to
claim 1, wherein the second nozzle is formed inside the shape
defining member.
4. The pulling-up-type continuous casting apparatus according to
claim 3, further comprising a projection disposed on the shape
defining member, the projection being disposed at an end on a side
of the shape defining member where the molten metal passes through,
the projection extending in a pulling-up direction, wherein a tip
of the second nozzle is formed on a top surface of the
projection.
5. The pulling-up-type continuous casting apparatus according to
claim 1, wherein an angle between a surface of the cast-metal
article and a flux of the gas blown from the second nozzle is equal
to or less than 25 degrees.
6. The pulling-up-type continuous casting apparatus according to
claim 1, wherein the gas blown from the second nozzle is the same
gas as the cooling gas blown from the first nozzle.
7. A pulling-up-type continuous casting apparatus comprising: a
holding furnace that holds molten metal; a shape defining member
disposed near a molten-metal surface of the molten metal held in
the holding furnace, the shape defining member being configured to
define a cross-sectional shape of a cast-metal article to be cast
as the molten metal passes through the shape defining member; a
nozzle that blows a cooling gas on the cast-metal article, the
cast-metal article being formed as the molten metal that has passed
through the shape defining member solidifies; and a projection
disposed on the shape defining member, the projection being
disposed at an end on a side of the shape defining member where the
molten metal passes through, the projection extending in a
pulling-up direction.
8. A pulling-up-type continuous casting method comprising: a step
of pulling up molten metal held in a holding furnace while making
the molten metal pass through a shape defining member, the shape
defining member being configured to define a cross-sectional shape
of a cast-metal article to be cast; and a step of blowing a cooling
gas on the cast-metal article, the cast-metal article being formed
from the molten metal that has passed through the shape defining
member, wherein in the step of blowing the cooling gas, a gas is
blown toward the cast-metal article in an obliquely upward
direction from below a place on the cast-metal article on which the
cooling gas is blown.
9. The pulling-up-type continuous casting method according to claim
8, further comprising a step of adjusting a flow rate of the gas
according to a flow rate of the cooling gas.
10. The pulling-up-type continuous casting method according to
claim 8, wherein the nozzle for blowing the gas toward the
cast-metal article in the obliquely upward direction is fixed on
the shape defining member.
11. The pulling-up-type continuous casting method according to
claim 8, wherein the nozzle for blowing the gas toward the
cast-metal article in the obliquely upward direction is formed
inside the shape defining member.
12. The pulling-up-type continuous casting method according to
claim 11, wherein a projection is provided on the shape defining
member, the projection being disposed at an end on a side of the
shape defining member where the molten metal passes through, the
projection extending in a pulling-up direction, and a tip of the
nozzle is formed on a top surface of the projection.
13. The pulling-up-type continuous casting method according to
claim 8, wherein an angle between a surface of the cast-metal
article and a flux of the gas blown toward the cast-metal article
in the obliquely upward direction is equal to or less than 25
degrees.
14. The pulling-up-type continuous casting method according to
claim 8, wherein the gas blown toward the cast-metal article in the
obliquely upward direction is the same gas as the cooling gas.
15. A pulling-up-type continuous casting method comprising: a step
of pulling up molten metal held in a holding furnace while making
the molten metal pass through a shape defining member, the shape
defining member being configured to define a cross-sectional shape
of a cast-metal article to be cast; and a step of blowing a cooling
gas on the cast-metal article, the cast-metal article being formed
from the molten metal that has passed through the shape defining
member, wherein a projection is provided on the shape defining
member, the projection being disposed at an end on a side of the
shape defining member where the molten metal passes through, the
projection extending in a pulling-up direction.
Description
TECHNICAL FIELD
[0001] The present invention relates to a pulling-up-type
continuous casting apparatus and a pulling-up-type continuous
casting method.
BACKGROUND ART
[0002] As a revolutionary continuous casting method that does not
requires any mold, Patent Literature 1 proposes a pulling-up-type
free casting method. As shown in Patent Literature 1, after a
starter is submerged under the surface of a melted metal (molten
metal) (i.e., molten-metal surface), the starter is pulled up, so
that some of the molten metal follows the starter and is drawn up
by the starter by the surface film of the molten metal and/or the
surface tension. Note that it is possible to continuously cast a
cast-metal article having a desired cross-sectional shape by
drawing the molten metal and cooling the drawn molten metal through
a shape defining member disposed in the vicinity of the
molten-metal surface.
[0003] In the ordinary continuous casting method, the shape of the
cast-metal article in the longitudinal direction as well as the
shape thereof in cross section is defined by the mold. In the
continuous casting method, in particular, since the solidified
metal (i.e., cast-metal article) needs to pass through the inside
of the mold, the cast-metal article has such a shape that it
extends in a straight-line shape in the longitudinal direction.
[0004] In contrast to this, the shape defining member used in the
free casting method defines only the cross-sectional shape of the
cast-metal article, while it does not define the shape in the
longitudinal direction. Further, since the shape defining member
can be moved in the direction parallel to the molten-metal surface
(i.e., in the horizontal direction), cast-metal articles having
various shapes in the longitudinal direction can be produced. For
example, Patent Literature 1 discloses a hollow cast-metal article
(i.e., a pipe) having a zigzag shape or a helical shape in the
longitudinal direction rather than the straight-line shape.
CITATION LIST
Patent Literature
[0005] Patent Literature 1: Japanese Unexamined Patent Application
Publication No. 2012-61518
SUMMARY OF INVENTION
Technical Problem
[0006] The present inventors have found the following problem.
[0007] In the free casting method disclosed in Patent Literature 1,
the molten metal drawn up through the shape defining member is
cooled by a cooling gas. Specifically, a cooling gas is blown on
the cast metal immediately after it is solidified and the molten
metal is thereby indirectly cooled. It should be noted that by
increasing the flow rate of the cooling gas, the casting speed can
be increased and the productively can be thereby improved. However,
there has been a problem that when the flow rate of the cooling gas
is increased, an undulation occurs in the molten metal drawn up
from the shape defining member due to the cooling gas and hence the
size accuracy and the surface quality of the cast-metal article
deteriorate.
[0008] The present invention has been made in view of the
above-described problem, and an object thereof is to provide a
pulling-up-type continuous casting apparatus capable of producing
cast-metal articles having excellent size accuracy and surface
quality, and having excellent productivity.
Solution to Problem
[0009] A pulling-up-type continuous casting apparatus according to
an aspect of the present invention includes:
[0010] a holding furnace that holds molten metal;
[0011] a shape defining member disposed near a molten-metal surface
of the molten metal held in the holding furnace, the shape defining
member being configured to define a cross-sectional shape of a
cast-metal article to be cast as the molten metal passes through
the shape defining member;
[0012] a first nozzle that blows a cooling gas on the cast-metal
article, the cast-metal article being formed as the molten metal
that has passed through the shape defining member solidifies;
and
[0013] a second nozzle that blows a gas toward the cast-metal
article in an obliquely upward direction from below a place on the
cast-metal article on which the cooling gas is blown from the first
nozzle.
[0014] The above-described configuration makes it possible to
provide a pulling-up-type continuous casting apparatus capable of
producing cast-metal articles having excellent size accuracy and
surface quality, and having excellent productivity.
[0015] The second nozzle is preferably fixed on the shape defining
member or formed inside the shape defining member. This
configuration can reduce the necessary space.
[0016] Further, the pulling-up-type continuous casting apparatus
preferably further includes a projection disposed on the shape
defining member, the projection being disposed at an end on a side
of the shape defining member where the molten metal passes through,
the projection extending in a pulling-up direction. Further, a tip
of the second nozzle is preferably formed on a top surface of the
projection.
[0017] An angle between a surface of the cast-metal article and a
flux of the gas blown from the second nozzle is preferably equal to
or less than 25 degrees. This configuration can effectively block
the cooling gas.
[0018] Further, the gas blown from the second nozzle is preferably
the same gas as the cooling gas blown from the first nozzle. This
can simplify the equipment.
[0019] A pulling-up-type continuous casting apparatus according to
another aspect of the present invention includes:
[0020] a holding furnace that holds molten metal;
[0021] a shape defining member disposed near a molten-metal surface
of the molten metal held in the holding furnace, the shape defining
member being configured to define a cross-sectional shape of a
cast-metal article to be cast as the molten metal passes through
the shape defining member;
[0022] a nozzle that blows a cooling gas on the cast-metal article,
the cast-metal article being formed as the molten metal that has
passed through the shape defining member solidifies; and
[0023] a projection disposed on the shape defining member, the
projection being disposed at an end on a side of the shape defining
member where the molten metal passes through, the projection
extending in a pulling-up direction.
[0024] The above-described configuration makes it possible to
provide a pulling-up-type continuous casting apparatus capable of
producing cast-metal articles having excellent size accuracy and
surface quality, and having excellent productivity.
[0025] A pulling-up-type continuous casting method according to an
aspect of the present invention includes:
[0026] a step of pulling up molten metal held in a holding furnace
while making the molten metal pass through a shape defining member,
the shape defining member being configured to define a
cross-sectional shape of a cast-metal article to be cast; and
[0027] a step of blowing a cooling gas on the cast-metal article,
the cast-metal article being formed from the molten metal that has
passed through the shape defining member, in which
[0028] in the step of blowing the cooling gas, a gas is blown
toward the cast-metal article in an obliquely upward direction from
below a place on the cast-metal article on which the cooling gas is
blown.
[0029] The above-described configuration makes it possible to
provide a pulling-up-type continuous casting method capable of
producing cast-metal articles having excellent size accuracy and
surface quality, and having excellent productivity. The
pulling-up-type continuous casting method preferably further
includes a step of adjusting a flow rate of the gas according to a
flow rate of the cooling gas.
[0030] The nozzle for blowing the gas toward the cast-metal article
in the obliquely upward direction is preferably fixed on the shape
defining member or formed inside the shape defining member. This
configuration can reduce the necessary space.
[0031] Further, a projection is preferably provided on the shape
defining member, the projection being disposed at an end on a side
of the shape defining member where the molten metal passes through,
the projection extending in a pulling-up direction. Further, a tip
of the nozzle is preferably formed on a top surface of the
projection.
[0032] An angle between a surface of the cast-metal article and a
flux of the gas blown toward the cast-metal article in the
obliquely upward direction is preferably equal to or less than 25
degrees. This configuration can effectively block the cooling
gas.
[0033] Further, the gas blown toward the cast-metal article in the
obliquely upward direction is preferably the same gas as the
cooling gas. This can simplify the equipment.
[0034] A pulling-up-type continuous casting method according to
another aspect of the present invention includes:
[0035] a step of pulling up molten metal held in a holding furnace
while making the molten metal pass through a shape defining member,
the shape defining member being configured to define a
cross-sectional shape of a cast-metal article to be cast; and
[0036] a step of blowing a cooling gas on the cast-metal article,
the cast-metal article being formed from the molten metal that has
passed through the shape defining member, in which
[0037] a projection is provided on the shape defining member, the
projection being disposed at an end on a side of the shape defining
member where the molten metal passes through, the projection
extending in a pulling-up direction.
[0038] The above-described configuration makes it possible to
provide a pulling-up-type continuous casting method capable of
producing cast-metal articles having excellent size accuracy and
surface quality, and having excellent productivity.
Advantageous Effects of Invention
[0039] According to the present invention, it is possible to
provide a pulling-up-type continuous casting apparatus capable of
producing cast-metal articles having excellent size accuracy and
surface quality, and having excellent productivity.
BRIEF DESCRIPTION OF DRAWINGS
[0040] FIG. 1 is a schematic cross section of a free casting
apparatus according to a first exemplary embodiment;
[0041] FIG. 2 is a plan view of a shape defining member 102
according to the first exemplary embodiment;
[0042] FIG. 3 is a side view showing a positional relation between
a gas blowing-up nozzle 104 and a cooling gas nozzle 106 provided
in the free casting apparatus according to a first exemplary
embodiment;
[0043] FIG. 4 is a diagram for explaining an effect of an angle
.theta. between the flux of a blocking gas and the surface of cast
metal M3;
[0044] FIG. 5 is a graph for explaining an effect of an angle
.theta. between the flux of a blocking gas and the surface of cast
metal M3;
[0045] FIG. 6 is a plan view of a shape defining member 102
according to a modified example of the first exemplary
embodiment;
[0046] FIG. 7 is a side view of the shape defining member 102
according to the modified example of the first exemplary
embodiment;
[0047] FIG. 8 is a schematic cross section of a free casting
apparatus according to a second exemplary embodiment;
[0048] FIG. 9 is a schematic cross section of a free casting
apparatus according to a third exemplary embodiment;
[0049] FIG. 10 is a schematic cross section of a free casting
apparatus according to a modified example of the third exemplary
embodiment; and
[0050] FIG. 11 is a schematic cross section of a free casting
apparatus according to a fourth exemplary embodiment.
DESCRIPTION OF EMBODIMENTS
[0051] Specific exemplary embodiments to which the present
invention is applied are explained hereinafter in detail with
reference to the drawings. However, the present invention is not
limited to exemplary embodiments shown below. Further, the
following descriptions and the drawings are simplified as
appropriate for clarifying the explanation.
First Exemplary Embodiment
[0052] Firstly, a free casting apparatus (pulling-up-type
continuous casting apparatus) according to a first exemplary
embodiment is explained with reference to FIG. 1. FIG. 1 is a
schematic cross section of a free casting apparatus according to
the first exemplary embodiment. As shown in FIG. 1, the free
casting apparatus according to the first exemplary embodiment
includes a molten-metal holding furnace 101, a shape defining
member 102, a gas blowing-up nozzle(s) 104, an actuator(s) 105, a
cooling gas nozzle(s) 106, and a pulling-up machine 108. In FIG. 1,
the xy-plane forms a horizontal plane and the z-axis direction is
the vertical direction. More specifically, the positive direction
on the z-axis is the vertically upward direction.
[0053] The molten-metal holding furnace 101 contains molten metal
M1 such as aluminum or its alloy, and maintains the molten metal M1
at a predetermined temperature. In the example shown in FIG. 1,
since the molten-metal holding furnace 101 is not replenished with
molten metal during the casting process, the surface of molten
metal M1 (i.e., molten-metal surface) is lowered as the casting
process advances. Alternatively, the molten-metal holding furnace
101 may be replenished with molten metal as required during the
casting process so that the molten-metal surface is kept at a fixed
level. Note that the position of the solidification interface can
be raised by increasing the setting temperature of the holding
furnace and the position of the solidification interface can be
lowered by lowering the setting temperature of the holding furnace.
Needless to say, the molten metal M1 may be a metal or an alloy
other than aluminum.
[0054] The shape defining member 102 is made of ceramic or
stainless steel, for example, and disposed near the molten-metal
surface. In the example shown in FIG. 1, the shape defining member
102 is disposed so that a gap G between its principal surface on
the underside (molten metal side) and the molten-metal surface is
about 0.5 mm. By providing the gap G, it is possible to prevent the
shape defining member 102 from lowering the temperature of the
molten metal.
[0055] Meanwhile, the shape defining member 102 is in contact with
held molten metal M2, which is pulled up from the molten-metal
surface, on the periphery of its opening (molten-metal passage
section 103) through which molten metal passes. Therefore, the
shape defining member 102 can define the cross-sectional shape of
cast metal M3 to be cast while preventing oxide films formed on the
surface of the molten metal M1 and foreign substances floating on
the surface of the molten metal M1 from entering the cast metal M3.
The cast metal M3 shown in FIG. 1 is a solid cast-metal article
having a plate-like shape in a horizontal cross section
(hereinafter referred to as "lateral cross section").
[0056] Alternatively, the shape defining member 102 may be disposed
so that its underside principal surface is entirely in contact with
the molten-metal surface. In that case, the underside principal
surface may be coated with a mold wash having a heat-insulating
property so that the decrease in the temperature of the molten
metal due to the shape defining member 102 is reduced. Examples of
the mold wash include a vermiculite mold wash. The vermiculite mold
wash is a mold wash that is obtained by suspending refractory fine
particles made of silicon oxide (SiO.sub.2), iron oxide
(Fe.sub.2O.sub.3), aluminum oxide (Al.sub.2O.sub.3), or the like in
water.
[0057] FIG. 2 is a plane view of the shape defining member 102
according to the first exemplary embodiment. Note that the cross
section of the shape defining member 102 shown in FIG. 1
corresponds to a cross section taken along the line I-I in FIG. 2.
As shown in FIG. 2, the shape defining member 102 has, for example,
a rectangular shape as viewed from the top, and has a rectangular
opening (molten-metal passage section 103) having a thickness t1
and a width w1 at the center thereof. The molten metal passes
through the rectangular opening (molten-metal passage section 103).
Further, the xyz-coordinate system shown in FIG. 2 corresponds to
that shown in FIG. 1.
[0058] As shown in FIG. 1, the molten metal M1 follows the cast
metal M3 and is pulled up by the cast metal M3 by its surface film
and/or the surface tension. Further, the molten metal M1 passes
through the molten-metal passage section 103 of the shape defining
member 102. That is, as the molten metal M1 passes through the
molten-metal passage section 103 of the shape defining member 102,
an external force(s) is applied from the shape defining member 102
to the molten metal M1 and the cross-sectional shape of the cast
metal M3 is thereby defined. Note that the molten metal that
follows the cast metal M3 and is pulled up from the molten-metal
surface by the surface film of the molten metal and/or the surface
tension is called "held molten metal M2". Further, the boundary
between the cast metal M3 and the held molten metal M2 is the
solidification interface SIF.
[0059] As shown in FIG. 1, the gas blowing-up nozzle(s) (second
nozzle(s)) 104 is disposed and fixed on the shape defining member
102. It should be noted that the gas blowing-up nozzle 104 blows a
gas (hereinafter called "blocking gas") toward the cast metal M3 in
an obliquely upward direction in order to prevent a cooling gas
blown from the cooling gas nozzle 106 onto the cast metal M3 from
causing an undulation on the surface of the held molten metal M2.
Further, the gas blowing-up nozzle 104 supports the shape defining
member 102. Details of the gas blowing-up nozzle 104 are described
later. Note that a gas similar to the cooling gas can be used as
the blocking gas. Further, when the blocking gas is the same gas as
the cooling gas, the blocking gas can also be supplied from the
cooling gas supply unit (not shown). That is, the equipment can be
simplified and hence the use of the same gas is preferred. Note
that the gas blowing-up nozzle 104 does not necessarily have to be
fixed on the shape defining member 102.
[0060] The gas blowing-up nozzle 104 is connected to the actuator
105. The gas blowing-up nozzle 104 and the shape defining member
102 can be moved in the up/down direction (vertical direction) and
the horizontal direction by the actuator 105. This configuration
makes it possible, for example, to move the shape defining member
102 downward as the molten-metal surface is lowered due to the
advance of the casting process. Further, since the shape defining
member 102 can be moved in the horizontal direction, the shape in
the longitudinal direction of the cast metal M3 can be arbitrarily
changed.
[0061] The cooling gas nozzle 106 is cooling means for blowing a
cooling gas (such as air, nitrogen, and argon) supplied from the
cooling gas supply unit (not shown) on the cast metal M3 and
thereby cooling the cast metal M3. The position of the
solidification interface can be lowered by increasing the flow rate
of the cooling gas and the position of the solidification interface
can be raised by reducing the flow rate of the cooling gas. Note
that although it is not shown in the figure, the cooling gas nozzle
(cooling unit) 106 can also be moved in the horizontal direction
and the vertical direction in accordance with the movement of the
gas blowing-up nozzle 104 and the shape defining member 102.
[0062] By cooling the cast metal M3 by the cooling gas while
pulling up the cast metal M3 by using the pulling-up machine 108
connected to the starter ST, the held molten metal M2 located in
the vicinity of the solidification interface SIF is successively
solidified, and the cast metal M3 is thereby formed. The position
of the solidification interface can be raised by increasing the
pulling-up speed of the pulling-up machine 108 and the position of
the solidification interface can be lowered by reducing the
pulling-up speed.
[0063] Next, a positional relation between the gas blowing-up
nozzle 104 and the cooling gas nozzle 106 provided in the free
casting apparatus according to the first exemplary embodiment is
explained with reference to FIG. 3. FIG. 3 is a side view showing a
positional relation between the gas blowing-up nozzle 104 and the
cooling gas nozzle 106 provided in the free casting apparatus
according to the first exemplary embodiment.
[0064] As shown in FIG. 3, the flux of the cooling gas for cooling
the cast metal M3 is blown from the cooling gas nozzle 106 in a
direction roughly perpendicularly to the surface of the cast metal
M3. This is because the closer the blowing direction is to the
direction perpendicular to the surface, the more the cooling
efficiency improves. Further, the closer the tip of the cooling gas
nozzle 106 is to the cast metal M3, the more the casting speed can
be increased. The larger the flow rate of the cooling gas, the more
the casting speed can be increased. Further, the closer the place
on which the cooling gas is blown is to the solidification
interface, the more the casting speed can be increased. The cooling
gas that has collided onto the surface of the cast metal M3
branches off into an upward direction and a downward direction
along the surface of the cast metal M3. Then, if there is nothing
that blocks the downward-branched cooling gas, the
downward-branched cooling gas causes an undulation on the surface
of the held molten metal M2. When the flow rate of the cooling gas
is increased, this undulation becomes larger, thus deteriorating
the size accuracy and the surface quality of the cast-metal
article.
[0065] Therefore, in the free casting apparatus according to the
first exemplary embodiment, the gas blowing-up nozzle 104 blows a
blocking gas in an obliquely upward direction from a place located
on the shape defining member 102 as shown in FIG. 3. Note that as
is obvious from FIG. 3, it is necessary that the place on the
surface of the cast metal M3 on which the blocking gas is blown is
located between the place on the surface of the cast metal M3 on
which the cooling gas is blown and the solidification interface
SIF. By using the blocking gas, it is possible to block the cooling
gas that has branched in the downward direction along the surface
of the cast metal M3. As a result, it is possible to prevent (or
reduce) the occurrence of an undulation on the surface of the held
molten metal M2 and improve the size accuracy and the surface
quality of the cast-metal article. Further, it is possible to
increase the casting speed and improve the productivity compared to
the related art by increasing the flow rate of the cooling gas.
Further, the blocking gas can improve the cooling effect of the
cast metal M3. Note that the flow rate of the blocking gas is
preferably adjusted according to the flow rate of the cooling
gas.
[0066] Next, the effect of the angle .theta. between the flux of
the blocking gas and the surface of the cast metal M3 is explained
with reference to FIGS. 4 and 5. FIG. 4 is a schematic diagram for
explaining the effect of the angle .theta. between the flux of the
blocking gas and the surface of the cast metal M3. Letting "Q0",
"Q1" and "Q2" stand for the total flow rate of the blocking gas
blown from the gas blowing-up nozzle 104, the flow rate of the
blocking gas that has branched downward, and the flow rate of the
blocking gas that has branched upward, respectively, as shown in
FIG. 4, a relation "Q0=Q1+Q2" holds. Note that the blocking gas is
blown so that the angle of the blocking gas with respect to the
surface of the cast metal M3 is the angle .theta..
[0067] FIG. 5 is a graph for explaining the effect of the angle
.theta. between the flux of the blocking gas and the surface of the
cast metal M3. As shown in FIG. 5, as the angle .theta. between the
flux of the blocking gas and the surface of the cast metal M3
changes, the ratio (%) of the flow rate Q1 of the downward-branched
blocking gas to the total flow rate Q0 changes. This ratio (%) can
be calculated by an expression "1/2.times.(1-cos
.theta.).times.100". FIG. 5 shows a plot in accordance with this
expression. The horizontal axis in FIG. 5 indicates angles .theta.
(degrees) and the vertical axis indicates ratios Q1\Q0 (%) of the
flow rate Q1 of the downward-branched blocking gas to the total
flow rate Q0. When the ratio Q1 \Q0 (%) increases, the blocking gas
itself causes an undulation on the surface of the held molten metal
M2. The ratio Q1 \Q0 (%) is preferably equal to or less than 5% and
hence the angle .theta. is preferably equal to or less than 25
degrees.
[0068] Next, a free casting method according to the first exemplary
embodiment is explained with reference to FIG. 1.
[0069] Firstly, a starter ST is lowered and made to pass through
the molten-metal passage section 103 of the shape defining member
102, and the tip of the starter ST is submerged into the molten
metal M1.
[0070] Next, the starter ST starts to be pulled up at a
predetermined speed. Note that even when the starter ST is pulled
away from the molten-metal surface, the molten metal M1 follows the
starter ST and is pulled up from the molten-metal surface by the
surface film and/or the surface tension. That is, the held molten
metal M2 is formed. As shown in FIG. 1, the held molten metal M2 is
formed in the molten-metal passage section 103 of the shape
defining member 102. That is, the held molten metal M2 is shaped
into a given shape by the shape defining member 102.
[0071] Next, since the starter ST is cooled by the cooling gas
blown from the cooling gas nozzle 106, the held molten metal M2
successively solidifies from its upper side toward its lower side.
As a result, the cast metal M3 grows. In this manner, it is
possible to continuously cast the cast metal M3.
[0072] As described above, the free casting apparatus according to
the first exemplary embodiment is equipped with the gas blowing-up
nozzle 104 that blows a blocking gas in an obliquely upward
direction from a place located on the shape defining member 102. By
using this blocking gas, it is possible to block the cooling gas
that has branched in the downward direction along the surface of
the cast metal M3. As a result, it is possible to prevent (or
reduce) the occurrence of an undulation on the surface of the held
molten metal M2 and improve the size accuracy and the surface
quality of the cast-metal article.
Modified Example of First Exemplary Embodiment
[0073] Next, a free casting apparatus according to a modified
example of the first exemplary embodiment is explained with
reference to FIGS. 6 and 7. FIG. 6 is a plan view of a shape
defining member 102 according to the modified example of the first
exemplary embodiment. FIG. 7 is a side view of the shape defining
member 102 according to the modified example of the first exemplary
embodiment. Note that the xyz-coordinate systems shown in FIGS. 6
and 7 correspond to that shown in FIG. 1.
[0074] The shape defining member 102 according to the first
exemplary embodiment shown in FIG. 2 is composed of one plate.
Therefore, the thickness t1 and the width w1 of the molten-metal
passage section 103 are fixed. In contrast to this, the shape
defining member 102 according to the modified example of the first
exemplary embodiment includes four rectangular shape defining
plates 102a, 102b, 102c and 102d as shown in FIG. 6. That is, the
shape defining member 102 according to the modified example of the
first exemplary embodiment is divided into a plurality of sections.
With this configuration, it is possible to change the thickness t1
and the width w1 of the molten-metal passage section 103. Further,
the four rectangular shape defining plates 102a, 102b, 102c and
102d can be moved in unison in the z-axis direction.
[0075] As shown in FIG. 6, the shape defining plates 102a and 102b
are arranged to be opposed to each other in the x-axis direction.
Further, as shown in FIG. 7, the shape defining plates 102a and
102b are disposed at the same height in the z-axis direction. The
gap between the shape defining plates 102a and 102b defines the
width w1 of the molten-metal passage section 103. Further, since
each of the shape defining plates 102a and 102b can be
independently moved in the x-axis direction, the width w1 can be
changed. Note that, as shown in FIGS. 6 and 7, a laser displacement
gauge S1 and a laser reflector plate S2 may be provided on the
shape defining plates 102a and 102b, respectively, in order to
measure the width w1 of the molten-metal passage section 103.
[0076] Further, as shown in FIG. 6, the shape defining plates 102c
and 102d are arranged to be opposed to each other in the y-axis
direction. Further, the shape defining plates 102c and 102c are
disposed at the same height in the z-axis direction. The gap
between the shape defining plates 102c and 102d defines the
thickness t1 of the molten-metal passage section 103. Further,
since each of the shape defining plates 102c and 102d can be
independently moved in the y-axis direction, the thickness t1 can
be changed. The shape defining plates 102a and 102b are disposed in
such a manner that they are in contact with the top sides of the
shape defining plates 102c and 102d.
[0077] Next, a driving mechanism for the shape defining plate 102a
is explained with reference to FIGS. 6 and 7. As shown in FIGS. 6
and 7, the driving mechanism for the shape defining plate 102a
includes slide tables T1 and T2, linear guides G11, G12, G21 and
G22, actuators A1 and A2, and rods R1 and R2. Note that although
each of the shape defining plates 102b, 102c and 102d also includes
its driving mechanism as in the case of the shape defining plate
102a, the illustration of them is omitted in FIGS. 6 and 7.
[0078] As shown in FIGS. 6 and 7, the shape defining plate 102a is
placed and fixed on the slide table T1, which can be slid in the
x-axis direction. The slide table T1 is slidably placed on a pair
of linear guides G11 and G12 extending in parallel with the x-axis
direction. Further, the slide table T1 is connected to the rod R1
extending from the actuator A1 in the x-axis direction. With the
above-described configuration, the shape defining plate 102a can be
slid in the x-axis direction.
[0079] Further, as shown in FIGS. 6 and 7, the linear guides G11
and G12 and the actuator A1 are placed and fixed on the slide table
T2, which can be slid in the z-axis direction. The slide table T2
is slidably placed on a pair of linear guides G21 and G22 extending
in parallel with the z-axis direction. Further, the slide table T2
is connected to the rod R2 extending from the actuator A2 in the
z-axis direction. The linear guides G21 and G22 and the actuator A2
are fixed on a horizontal floor surface or a horizontal pedestal
(not shown). With the above-described configuration, the shape
defining plate 102a can be slid in the z-axis direction. Note that
examples of the actuators A1 and A2 include a hydraulic cylinder,
an air cylinder, and a motor.
Second Exemplary Embodiment
[0080] Next, a free casting apparatus according to a second
exemplary embodiment is explained with reference to FIG. 8. FIG. 8
is a schematic cross section of a free casting apparatus according
to the second exemplary embodiment. Note that the xyz-coordinate
system shown in FIG. 8 also corresponds to that shown in FIG. 1. In
the free casting apparatus according to the first exemplary
embodiment, the gas blowing-up nozzle 104 is formed on the shape
defining member 102. In contrast to this, in the free casting
apparatus according to the second exemplary embodiment, a gas
blowing-up nozzle(s) 204 is formed inside a shape defining member
202. In other words, a passage(s) for a blocking gas is formed
inside the shape defining member 202. In the free casting apparatus
according to the second exemplary embodiment, by forming the
passage(s) for the blocking gas inside the shape defining member
202, the space necessary for the free casting apparatus is reduced
in the second exemplary embodiment even further than it is in the
first exemplary embodiment.
[0081] In the free casting apparatus according to the second
exemplary embodiment, the gas blowing-up nozzle 204 that blows a
blocking gas in an obliquely upward direction is disposed inside
the shape defining member 202. Meanwhile, similarly to the first
exemplary embodiment, it is necessary that the place on the surface
of the cast metal M3 on which the blocking gas is blown is located
between the place on the surface of the cast metal M3 on which the
cooling gas is blown and the solidification interface SIF. Note
that the effect of the angle .theta. between the flux of the
blocking gas and the surface of the cast metal M3 is similar to
that in the first exemplary embodiment. Therefore, the angle
.theta. is preferably equal to or less than 25 degrees.
[0082] The cooling gas that has branched in the downward direction
along the surface of the cast metal M3 can be blocked by the
blocking gas blown up in an obliquely upward direction from the gas
blowing-up nozzle 204 formed inside the shape defining member 202.
As a result, it is possible to prevent (or reduce) the occurrence
of an undulation on the surface of the held molten metal M2 and
improve the size accuracy and the surface quality of the cast-metal
article. In addition, it is possible to increase the casting speed
and improve the productivity compared to the related art by
increasing the flow rate of the cooling gas. Further, the blocking
gas can improve the cooling effect of the cast metal M3.
Third Exemplary Embodiment
[0083] Next, a free casting apparatus according to a third
exemplary embodiment is explained with reference to FIG. 9. FIG. 9
is a schematic cross section of a free casting apparatus according
to the third exemplary embodiment. Note that the xyz-coordinate
system shown in FIG. 9 also corresponds to that shown in FIG. 1. In
the free casting apparatus according to the first exemplary
embodiment, the gas blowing-up nozzle 104 is formed on the shape
defining member 102. In contrast to this, in the free casting
apparatus according to the third exemplary embodiment, a blocking
wall(s) (projection(s)) 302a for blocking the cooling gas that has
branched in the downward direction along the surface of the cast
metal M3 is formed. The blocking wall 302a is formed on a shape
defining member near the end on the side of the shape defining
member 302 where the molten-metal passage section 103 passes
through.
[0084] It should be noted that the height of the blocking wall 302a
and distance between the molten-metal passage section 103 and the
blocking wall 302a are determined according to the shape in the
longitudinal direction of the cast metal M3. Specifically, the
higher the blocking wall 302a is, the more the effect of blocking
the downward-branched cooling gas improves. Further, the shorter
the distance between the molten-metal passage section 103 and the
blocking wall 302a is, the more the effect of blocking the
downward-branched cooling gas improves. However, the flexibility in
the shape in the longitudinal direction of the cast metal M3
decreases, thus leading to the cast metal M3 extending on a
straight line.
[0085] Note that there is no particular restriction on the width W
of the blocking wall 302a.
[0086] Here, FIG. 10 is a schematic cross section of a free casting
apparatus according to a modified example of the third exemplary
embodiment. For example, as shown in FIG. 10, the blocking wall
302a may reach the outer edge (the end on the outer side) of the
shape defining member 302.
[0087] In the free casting apparatus according to the third
exemplary embodiment, the cooling gas that has branched in the
downward direction along the surface of the cast metal M3 can be
blocked by the blocking wall 302a. As a result, it is possible to
prevent (or reduce) the occurrence of an undulation on the surface
of the held molten metal M2 and improve the size accuracy and the
surface quality of the cast-metal article. Further, it is possible
to increase the casting speed and improve the productivity compared
to the related art by increasing the flow rate of the cooling
gas.
Fourth Exemplary Embodiment
[0088] Next, a free casting apparatus according to a fourth
exemplary embodiment is explained with reference to FIG. 11. FIG.
11 is a schematic cross section of a free casting apparatus
according to the fourth exemplary embodiment. Note that the
xyz-coordinate system shown in FIG. 11 also corresponds to that
shown in FIG. 1. In the free casting apparatus according to the
second exemplary embodiment, the gas blowing-up nozzle 204 is
formed inside the shape defining member 202. Further, in the free
casting apparatus according to the third exemplary embodiment, the
blocking wall 302a is formed on the shape defining member 302. In
contrast to this, in the free casting apparatus according to the
fourth exemplary embodiment, a gas blowing-up nozzle(s) 404 is
formed inside a shape defining member 402 and a blocking wall(s)
402a. In other words, a passage(s) for a blocking gas is formed
inside the shape defining member 402 and the blocking wall(s) 402a.
Further, tip(s) (blowing hole(s)) of the gas blowing-up nozzle(s)
404 is formed on the top surface of the blocking wall(s) 402a.
[0089] In the free casting apparatus according to the fourth
exemplary embodiment, the gas blowing-up nozzle 404 that blows up a
blocking gas in an obliquely upward direction is disposed inside
the shape defining member 402 and the blocking wall 402a.
Meanwhile, similarly to the first and second exemplary embodiments,
it is necessary that the place on the surface of the cast metal M3
on which the blocking gas is blown is located between the place on
the surface of the cast metal M3 on which the cooling gas is blown
and the solidification interface SIF. Note that the effect of the
angle .theta. between the flux of the blocking gas and the surface
of the cast metal M3 is similar to that in the first exemplary
embodiment. Therefore, the angle .theta. is preferably equal to or
less than 25 degrees.
[0090] The cooling gas that has branched in the downward direction
along the surface of the cast metal M3 can be blocked by both the
blocking wall 402a and the blocking gas blown up in an obliquely
upward direction from the inside of that blocking wall 402a. As a
result, it is possible to prevent (or reduce) the occurrence of an
undulation on the surface of the held molten metal M2 and improve
the size accuracy and the surface quality of the cast-metal
article. In addition, it is possible to increase the casting speed
and improve the productivity compared to the related art by
increasing the flow rate of the cooling gas. Further, the blocking
gas can improve the cooling effect of the cast metal M3.
[0091] Note that the present invention is not limited to the
above-described exemplary embodiments, and various modifications
can be made without departing the spirit and scope of the present
invention.
TABLE-US-00001 Reference Signs List 101 MOLTEN METAL HOLDING
FURNACE 102, 202, 302, 402 SHAPE DEFINING MEMBER 102a-102d SHAPE
DEFINING PLATE 103 MOLTEN-METAL PASSAGE SECTION 104, 204, 404 GAS
BLOWING-UP NOZZLE 105 ACTUATOR 106 COOLING GAS NOZZLE 108
PULLING-UP MACHINE 302a, 402a BLOCKING WALL (PROJECTION) A1, A2
ACTUATOR G11, G12, G21, G22 LINEAR GUIDE M1 MOLTEN METAL M2 HELD
MOLTEN METAL M3 CAST METAL R1, R2 ROD S1 LASER DISPLACEMENT GAUGE
S2 LASER REFLECTOR PLATE SIF SOLIDIFICATION INTERFACE ST STARTER
T1, T2 SLIDE TABLE
* * * * *