U.S. patent application number 14/908908 was filed with the patent office on 2016-06-09 for pulling-up-type continuous casting method.
This patent application is currently assigned to TOYOTA JIDOSHA KABUSHIKI KAISHA. The applicant listed for this patent is TOYOTA JIDOSHA KABUSHIKI KAISHA. Invention is credited to Naoaki SUGIURA, Yusuke YOKOTA.
Application Number | 20160158833 14/908908 |
Document ID | / |
Family ID | 52431252 |
Filed Date | 2016-06-09 |
United States Patent
Application |
20160158833 |
Kind Code |
A1 |
SUGIURA; Naoaki ; et
al. |
June 9, 2016 |
PULLING-UP-TYPE CONTINUOUS CASTING METHOD
Abstract
A pulling-up-type continuous casting method according to an
aspect of the present disclosure is a pulling-up-type continuous
casing method for pulling up molten metal held in a holding furnace
by using a starter. When the starter is accelerated to a
predetermined pulling-up speed at a start of casting, the
pulling-up-type continuous casting method includes a first
acceleration section in which the starter is accelerated from a
standstill state to a first speed at a first acceleration, a second
acceleration section in which the starter is accelerated from the
first speed to a second speed at a second acceleration, and a
constant speed section in which the starter is pulled up at the
first speed, the constant speed section being positioned between
the first and second acceleration sections.
Inventors: |
SUGIURA; Naoaki;
(Takahama-shi, JP) ; YOKOTA; Yusuke; (Toyota-shi,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
TOYOTA JIDOSHA KABUSHIKI KAISHA |
Toyota-shi, Aichi |
|
JP |
|
|
Assignee: |
TOYOTA JIDOSHA KABUSHIKI
KAISHA
Toyota-shi, Aichi
JP
|
Family ID: |
52431252 |
Appl. No.: |
14/908908 |
Filed: |
June 5, 2014 |
PCT Filed: |
June 5, 2014 |
PCT NO: |
PCT/JP2014/003010 |
371 Date: |
January 29, 2016 |
Current U.S.
Class: |
164/480 |
Current CPC
Class: |
B22D 11/01 20130101;
B22D 11/041 20130101; B22D 11/145 20130101; B22D 11/04
20130101 |
International
Class: |
B22D 11/041 20060101
B22D011/041; B22D 11/14 20060101 B22D011/14 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 30, 2013 |
JP |
2013-158202 |
Claims
1. A pulling-up-type continuous casting method for pulling up
molten metal held in a holding furnace by using a starter, wherein
when the starter is accelerated to a predetermined pulling-up speed
at a start of casting, the pulling-up-type continuous casting
method includes: a first acceleration section in which the starter
is accelerated from a standstill state to a first speed at a first
acceleration; a second acceleration section in which the starter is
accelerated from the first speed to a second speed at a second
acceleration; and a constant speed section in which the starter is
pulled up at the first speed, the constant speed section being
positioned between the first and second acceleration sections.
2. The pulling-up-type continuous casting method according to claim
1, wherein the first acceleration is an acceleration that will
cause a tearing in the molten metal pulled-up by the starter before
the pulling-up speed of the starter reaches the predetermined
pulling-up speed when the starter is continuously accelerated from
the standstill state at that acceleration, and the second
acceleration is an acceleration that will cause a tearing in the
molten metal pulled-up by the starter before the pulling-up speed
of the starter reaches the predetermined pulling-up speed when the
starter is continuously accelerated from the standstill state at
that acceleration.
3. The pulling-up-type continuous casting method according to claim
1, wherein the first and second accelerations are equal to each
other.
4. The pulling-up-type continuous casting method according to claim
3, wherein each of the first and second accelerations is a maximum
acceleration that a pulling-up machine that pulls up the starter
can deliver.
5. The pulling-up-type continuous casting method according to claim
1, wherein the pulling-up-type continuous casting method further
includes: a third acceleration section in which the starter is
accelerated from the second speed to a third speed at a third
acceleration; and a constant speed section in which the starter is
pulled up at the second speed, the constant speed section being
positioned between the second and third acceleration sections.
6. The pulling-up-type continuous casting method according to claim
1, wherein the second acceleration is higher than the first
acceleration.
7. The pulling-up-type continuous casting method according to claim
6, wherein the second acceleration is a maximum acceleration that a
pulling-up machine that pulls up the starter can deliver.
Description
TECHNICAL FIELD
[0001] The present invention relates to a pulling-up-type
continuous casting method.
BACKGROUND ART
[0002] Patent Literature 1 proposed a free casting method as a
revolutionary pulling-up-type continuous casting method that does
not requires any mold. As shown in Patent Literature 1, after a
starter is submerged into 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 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 in the
longitudinal direction as well as the shape 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 inside the mold, the cast-metal article has a
shape extending on a straight-line 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,
a cooling gas is blown on cast metal following the starter
immediately after the cast metal is solidified and the molten metal
is thereby indirectly cooled. It should be noted that the casting
process needs to be advanced in a state where the speed at which
the solidification advances from the top toward the bottom of the
cast metal (hereinafter called a "solidifying speed") is
substantially equal to the pulling-up speed. For example, if only
the pulling-up speed is increased while maintaining the cooling
power for the pulled-up molten metal unchanged (i.e., while
maintaining the solidifying speed unchanged), the solidification
interface rises and hence the pulled-up molten metal is torn apart.
That is, if the cooling power is determined, an appropriate
pulling-up speed corresponding to that cooling power is determined.
Note that to increase the pulling-up speed and thereby improve
productivity, the above-described cooling power needs to be
increased.
[0008] At the start of casting, the starter is accelerated from a
standstill state to a desired pulling-up speed (i.e., the
above-described appropriate pulling-up speed corresponding to the
cooling power). However, there has been a problem that if the
acceleration for the pulling-up operation is too high, the molten
metal pulled-up by the starter is torn apart before the pulling-up
speed of the starter reaches the desired pulling-up speed, thus
making the casting itself impossible. Further, there is another
problem that if the acceleration for the pulling-up operation is
lowered in order to prevent the molten metal from being torn apart
due to the acceleration, it takes time before the pulling-up speed
of the starter reaches the desired pulling-up speed, thus
deteriorating productivity.
[0009] The present invention has been made in view of the
above-described problems, and an object thereof is to provide a
pulling-up-type continuous casting method that has excellent
productivity while preventing the pulled-up molten metal from being
torn apart during the acceleration.
Solution to Problem
[0010] A pulling-up-type continuous casting method according to an
aspect of the present invention is
[0011] a pulling-up-type continuous casing method for pulling up
molten metal held in a holding furnace by using a starter, in
which
[0012] when the starter is accelerated to a predetermined
pulling-up speed at a start of casting, the pulling-up-type
continuous casting method includes:
[0013] a first acceleration section in which the starter is
accelerated from a standstill state to a first speed at a first
acceleration;
[0014] a second acceleration section in which the starter is
accelerated from the first speed to a second speed at a second
acceleration; and
[0015] a constant speed section in which the starter is pulled up
at the first speed, the constant speed section being positioned
between the first and second acceleration sections.
[0016] This configuration can provide a pulling-up-type continuous
casting method that has excellent productivity while preventing the
pulled-up molten metal from being torn apart during the
acceleration.
[0017] The first acceleration is preferably an acceleration that
will cause a tearing in the molten metal pulled-up by the starter
before the pulling-up speed of the starter reaches the
predetermined pulling-up speed if the starter is continuously
accelerated from the standstill state at that acceleration, and the
second acceleration is preferably an acceleration that will cause a
tearing in the molten metal pulled-up by the starter before the
pulling-up speed of the starter reaches the predetermined
pulling-up speed if the starter is continuously accelerated from
the standstill state at that acceleration. It is possible to
improve productivity even further.
[0018] Further, the first and second accelerations are preferably
equal to each other. In this case, each of the first and second
accelerations is particularly preferably a maximum acceleration
that a pulling-up machine that pulls up the starter can
deliver.
[0019] Further, the pulling-up-type continuous casting method may
further include a third acceleration section in which the starter
is accelerated from the second speed to a third speed at a third
acceleration, and a constant speed section in which the starter is
pulled up at the second speed, the constant speed section being
positioned between the second and third acceleration sections.
[0020] Alternatively, the second acceleration may be higher than
the first acceleration. In this case, the second acceleration is
preferably a maximum acceleration that a pulling-up machine that
pulls up the starter can deliver.
Advantageous Effects of Invention
[0021] According to the present invention, it is possible to
provide a pulling-up-type continuous casting method that has
excellent productivity while preventing the pulled-up molten metal
from being torn apart during the acceleration.
BRIEF DESCRIPTION OF DRAWINGS
[0022] FIG. 1 is a schematic cross section of a free casting
apparatus according to a first exemplary embodiment;
[0023] FIG. 2 is a plan view of a shape defining member 102
according to the first exemplary embodiment;
[0024] FIG. 3 is a schematic graph showing a pulling-up speed
acceleration method according to the first exemplary
embodiment;
[0025] FIG. 4 is a schematic graph showing a pulling-up speed
acceleration method according to a modified example 1 of the first
exemplary embodiment;
[0026] FIG. 5 is a schematic graph showing a pulling-up speed
acceleration method according to a modified example 2 of the first
exemplary embodiment;
[0027] FIG. 6 is a plan view of a shape defining member 102
according to a second exemplary embodiment; and
[0028] FIG. 7 is a side view of the shape defining member 102
according to the second exemplary embodiment.
DESCRIPTION OF EMBODIMENTS
[0029] 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
[0030] 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 support rod 104, an actuator 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.
[0031] 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 at which the molten metal M1 has
fluidity. 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 SIF can be raised by
increasing the setting temperature of the holding furnace and the
position of the solidification interface SW 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.
[0032] 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 its underside principal surface
(undersurface) is in contact with the molten-metal surface. 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"). Note that
needless to say, there is no particular restriction on the
cross-sectional shape of the cast metal M3. The cast metal M3 may
be, for example, a hollow cast-metal article such as a circular
pipe and a rectangular pipe.
[0033] 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).
[0034] Note that the xyz-coordinate system shown in FIG. 2
corresponds to that shown in FIG. 1.
[0035] 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,
the surface tension, and the like. 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 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, the surface
tension, and the like 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.
[0036] The support rod 104 supports the shape defining member
102.
[0037] The support rod 104 is connected to the actuator 105. By the
actuator 105, the shape defining member 102 can be moved in the
up/down direction (vertical direction) and in the horizontal
direction through the support rod 104. With this configuration, it
is possible 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 changed.
[0038] The cooling gas nozzle (cooling unit) 106 is cooling means
for blowing a cooling gas (such as air, nitrogen, and argon)
supplied from a cooling gas supply unit (not shown) on the cast
metal M3 and thereby cooling the cast metal M3. The position of the
solidification interface SIF can be lowered by increasing the flow
rate of the cooling gas and 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 in the vertical direction in
accordance with the movement of the shape defining member 102.
[0039] 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 SIF can be raised by increasing the
pulling-up speed of the pulling-up machine 108 and can be lowered
by reducing the pulling-up speed.
[0040] Next, a free casting method according to a first exemplary
embodiment is explained with reference to FIG. 1.
[0041] Firstly, the 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.
[0042] 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, the surface tension, and the like, thus forming the
held molten metal M2. 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.
[0043] 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.
[0044] It should be noted that at the start of the casting, the
pulling-up speed is accelerated (i.e., increased) from a standstill
state to a desired pulling-up speed (i.e., an appropriate
pulling-up speed corresponding to cooling power by the cooling gas
nozzle 106). One of the features of the free casting method
according to the first exemplary embodiment lies in the pulling-up
speed acceleration method at the start of the casting. The
pulling-up speed acceleration method at the start of the casting is
explained hereinafter with reference to FIG. 3.
[0045] FIG. 3 is a schematic graph showing a pulling-up speed
acceleration method according to the first exemplary embodiment.
The horizontal axis indicates the time and the vertical axis
indicates the pulling-up speed (mm/s). In FIG. 3, a case where the
starter is continuously accelerated at an acceleration a1 is
indicated by an alternate long and short dash line for a
comparison. In such a case, a tearing occurs in the held molten
metal M2 before the pulling-up speed of the starter reaches a
maximum pulling-up speed Vmax, which is the appropriate pulling-up
speed corresponding to the cooling power by the cooling gas nozzle
106. Here, the acceleration a1 is, for example, the maximum
acceleration that the pulling-up machine 108 can deliver. In FIG.
3, a tearing occurs in the held molten metal M2 at the point when
the pulling-up speed reaches a speed V1.
[0046] Further, in FIG. 3, another case where the starter is
continuously accelerated at an acceleration a2 to prevent the
tearing of the held molten metal M2 is indicated by another
alternate long and short dash line for a comparison. Here, the
acceleration a2 is the maximum acceleration at which the pulling-up
speed can reach the maximum pulling-up speed Vmax without causing
any tearing in the held molten metal M2 even when the starter is
continuously accelerated from the standstill state at that
acceleration. That is, if the starter is continuously accelerated
from the standstill state at an acceleration higher than the
acceleration a2, a tearing occurs in the held molten metal M2
before the pulling-up speed reaches the maximum pulling-up speed
Vmax. On the other hand, if the starter is continuously accelerated
from the standstill state at an acceleration equal to or lower than
the acceleration a2, the pulling-up speed can reach the maximum
pulling-up speed Vmax without causing any tearing in the held
molten metal M2. As shown in FIG. 3, when the starter is
continuously accelerated at the acceleration a2, the pulling-up
speed reaches the maximum pulling-up speed Vmax at a time t2.
Therefore, productivity is poor.
[0047] Therefore, in the free casting method according to the first
exemplary embodiment, a constant-speed operation section is
provided between acceleration operation sections in order to
improve productivity while preventing the held molten metal M2 from
being torn apart. Specifically, in FIG. 3, the pulling-up operation
is switched from the acceleration operation, in which the starter
is accelerated at the acceleration a1, to the constant-speed
operation before the pulling-up speed reaches the speed V1 at which
a tearing would otherwise occur in the held molten metal M2. In
FIG. 3, the pulling-up operation is switched to the constant-speed
operation at the point when the pulling-up speed reaches a speed
V11 (<V1). Note that the speed V11 is lower than the maximum
pulling-up speed Vmax corresponding to the cooling power.
Therefore, the position of the solidification interface SW is
lowered in the constant-speed operation section in which the
starter is pulled up at the speed V11.
[0048] After the pulling-up speed is kept at the speed V11 for a
predetermined period, the pulling-up operation is switched from the
constant-speed operation to the acceleration operation in which the
starter is accelerated at the acceleration a1 again. By providing
the constant-speed operation section and thereby lowering the
position of the solidification interface SIF, the tearing of the
held molten metal M2, which would otherwise occur at the speed V1,
can be prevented after the acceleration operation in which the
starter is accelerated at the acceleration a1 is resumed. The
acceleration in this acceleration operation section does not
necessarily have to be equal to the acceleration in the previous
acceleration operation section. However, the accelerations in both
of the acceleration operation sections are preferably higher than
the acceleration a2 in view of the resulting improvement in
productivity. In other words, in view of the resulting improvement
in the productivity, the acceleration in the acceleration operation
section is preferably an acceleration that will cause a tearing in
the held molten metal M2 before the pulling-up speed reaches the
maximum pulling-up speed Vmax if the starter is continuously
accelerated from the standstill state at that acceleration.
[0049] Further, in the example shown in FIG. 3, the pulling-up
operation is switched to a constant-speed operation again at the
point when the pulling-up speed reaches a speed V12 (>V1). After
that, the pulling-up operation is switched to an acceleration
operation in which the starter is accelerated at the acceleration
a1 again and the pulling-up speed is eventually increased to the
maximum pulling-up speed Vmax. That is, two constant-speed
operation sections are provided. It should be noted that the number
of constant-speed operation sections is preferably as small as
possible in view of productivity. On the other hand, there are
cases in which if the number of constant-speed operation sections
is only one, a tearing occurs in the held molten metal M2 before
the pulling-up speed reaches the maximum pulling-up speed Vmax.
Therefore, a plurality of constant-speed operation sections may be
provided in order to increase the pulling-up speed to the maximum
pulling-up speed Vmax while preventing the held molten metal M2
from being torn apart.
[0050] Further, productivity can be improved by reducing the length
of each constant-speed operation section. On the other hand, if the
constant-speed operation section is too short, the position of the
solidification interface SW is not sufficiently lowered in the
constant-speed operation section. As a result, a tearing is likely
to occur in the held molten metal M2 when the pulling-up operation
is switched to the acceleration operation.
[0051] Further, in the free casting method according to the first
exemplary embodiment, the starter is accelerated at an acceleration
that is higher than the acceleration a2 at which no tearing occurs
in the held molten metal M2 even when the starter is continuously
accelerated at that acceleration. Therefore, as shown in FIG. 3,
the pulling-up speed reaches the maximum pulling-up speed Vmax at a
time t1 (<t2). Therefore, productivity is excellent.
Modified Example 1 of First Exemplary Embodiment
[0052] Next, a free casting method according to a modified example
1 of the first exemplary embodiment is explained with reference to
FIG. 4. FIG. 4 is a schematic graph showing a pulling-up speed
acceleration method according to the modified example 1 of the
first exemplary embodiment. In FIG. 4, a case where the starter is
continuously accelerated at an acceleration a3, which is lower than
the acceleration a1 and higher than the acceleration a2, is
indicated by another alternate long and short dash line for a
comparison. If the starter is continuously accelerated at the
acceleration a3, a tearing occurs in the held molten metal M2
before the pulling-up speed reaches the maximum pulling-up speed
Vmax. However, as shown in FIG. 4, the tearing occurs in the held
molten metal M2 at the point when the pulling-up speed reaches a
speed V2 higher than the speed V1.
[0053] Therefore, in the free casting method according to the
modified example 1 of the first exemplary embodiment, the
pulling-up operation is switched to the constant-speed operation at
the point when the pulling-up speed reaches a speed V21 that is
higher than the speed V1 and lower than the speed V2. That is, in
the example shown in FIG. 4, while the acceleration is lower than
that in the example shown in FIG. 3, the number of constant-speed
operation sections is only one. As shown above, the number of
constant-speed operation sections is preferably optimized according
to the acceleration. Further, the casting process is preferably
started with the acceleration a3, which is lower than the
acceleration a1, because a tearing is more likely to occur in the
held molten metal M2 immediately after the casting process is
started.
Modified Example 2 of First Exemplary Embodiment
[0054] Next, a free casting method according to a modified example
2 of the first exemplary embodiment is explained with reference to
FIG. 5. FIG. 5 is a schematic graph showing a pulling-up speed
acceleration method according to the modified example 2 of the
first exemplary embodiment. In FIG. 4, the acceleration before the
constant-speed operation section and the acceleration after the
constant-speed operation section are both the acceleration a3. In
contrast to this, in FIG. 5, the acceleration after the
constant-speed operation section is the acceleration a1, which is
higher than the acceleration a3 which is the acceleration before
the constant-speed operation section. This makes a time t4 at which
the pulling-up speed reaches the maximum pulling-up speed Vmax in
the modified example 2 earlier than the time t3 at which the
pulling-up speed reaches the maximum pulling-up speed Vmax in the
modified example 1. That is, the productivity in the free casting
method according to the modified example 2 is higher than that in
the free casting method according to the modified example 1.
[0055] As has been explained above, in the free casting method
according to the first exemplary embodiment, a constant-speed
operation section(s) is provided between acceleration operations at
the start of the casting. This can prevent the held molten metal M2
from being torn apart even when the starter is accelerated at an
acceleration that will cause a tearing in the held molten metal M2
if the starter is continuously accelerated at that acceleration.
Further, the pulling-up speed can be increased to the maximum
pulling-up speed Vmax in a shorter time period than the time period
that is required in the related art. Therefore, productivity is
excellent.
Second Exemplary Embodiment
[0056] Next, a free casting apparatus according to a second
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 second exemplary embodiment. FIG. 7 is a side view of the shape
defining member 102 according to the second exemplary embodiment.
Note that the xyz-coordinate systems shown in FIGS. 6 and 7
correspond to that shown in FIG. 1.
[0057] 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 second 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 second 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.
[0058] 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.
[0059] 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.
[0060] 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.
[0061] 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.
[0062] 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.
[0063] 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.
[0064] As has been explained above, in the free casting apparatus
according to the second exemplary embodiment, the shape of the
molten-metal passage section 103 can be changed. Therefore, the
cross-sectional shape of the cast metal M3 can be changed during
the casting process.
[0065] Further, control may be performed so that the shape of the
molten-metal passage section 103 is reduced in size in the
acceleration operation section at the start of the casting. The
tearing in the held molten metal M2 can be prevented or reduced
even further by reducing the mass of the held molten metal M2.
[0066] 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.
[0067] For example, the present invention can be applied to a
pulling-up-type continuous casting method in which the shape
defining member 102 is not used, provided that the molten metal is
pulled up by using a starter ST in the pulling-up-type continuous
casting method.
[0068] This application is based upon and claims the benefit of
priority from Japanese patent application No. 2013-158202, filed on
Jul. 30, 2013, the disclosure of which is incorporated herein in
its entirety by reference.
REFERENCE SIGNS LIST
[0069] 101 MOLTEN METAL HOLDING FURNACE [0070] 102 SHAPE DEFINING
MEMBER [0071] 102a-102d SHAPE DEFINING PLATE [0072] 103
MOLTEN-METAL PASSAGE SECTION [0073] 104 SUPPORT ROD [0074] 105
ACTUATOR [0075] 106 COOLING GAS NOZZLE [0076] 108 PULLING-UP
MACHINE [0077] A1, A2 ACTUATOR [0078] G11, G12, G21, G22 LINEAR
GUIDE [0079] M1 MOLTEN METAL [0080] M2 HELD MOLTEN METAL [0081] M3
CAST METAL [0082] R1, R2 ROD [0083] S1 LASER DISPLACEMENT GAUGE
[0084] S2 LASER REFLECTOR PLATE [0085] SIF SOLIDIFICATION INTERFACE
[0086] ST STARTER [0087] T1, T2 SLIDE TABLE
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