U.S. patent application number 14/638333 was filed with the patent office on 2015-09-10 for up-drawing continuous casting method.
The applicant listed for this patent is Toyota Jidosha Kabushiki Kaisha. Invention is credited to Naoaki Sugiura, Yusuke Yokota.
Application Number | 20150251243 14/638333 |
Document ID | / |
Family ID | 54016434 |
Filed Date | 2015-09-10 |
United States Patent
Application |
20150251243 |
Kind Code |
A1 |
Sugiura; Naoaki ; et
al. |
September 10, 2015 |
UP-DRAWING CONTINUOUS CASTING METHOD
Abstract
An up-drawing continuous casting method according to one aspect
of the invention is an up-drawing continuous casting method for
forming a bent shape in a cast casting by forming the casting in a
first direction and then changing an up-drawing direction to a
second direction and forming the casting in the second direction.
This up-drawing continuous casting method includes drawing up the
molten metal in the first direction; and changing the up-drawing
direction to a third direction in which an angle between the third
direction and the first direction is greater than an angle between
the second direction and the first direction, from after a portion
that will have the bent shape passes through the molten metal
passage portion until the portion that will have the bent shape
reaches a solidification interface, and then drawing up the molten
metal.
Inventors: |
Sugiura; Naoaki;
(Takahama-shi Aichi-ken, JP) ; Yokota; Yusuke;
(Toyota-shi Aichi-ken, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Toyota Jidosha Kabushiki Kaisha |
Toyota-shi Aichi-ken |
|
JP |
|
|
Family ID: |
54016434 |
Appl. No.: |
14/638333 |
Filed: |
March 4, 2015 |
Current U.S.
Class: |
164/459 |
Current CPC
Class: |
B22D 11/01 20130101;
B22D 11/1206 20130101; B22D 11/145 20130101 |
International
Class: |
B22D 11/01 20060101
B22D011/01; B22D 25/02 20060101 B22D025/02; B22D 11/12 20060101
B22D011/12 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 10, 2014 |
JP |
2014-046047 |
Claims
1. An up-drawing continuous casting method for forming a bent shape
in a cast casting by forming the casting in a first direction and
then changing an up-drawing direction to a second direction and
forming the casting in the second direction, the casting being
formed by drawing up molten metal held in a holding furnace from a
molten metal surface of the molten metal, passing the molten metal
through a molten metal passage portion of a shape determining
member that determines a sectional shape of the casting, and
solidifying the molten metal, the up-drawing continuous casting
method comprising: drawing up the molten metal in the first
direction; and changing the up-drawing direction to a third
direction in which an angle between the third direction and the
first direction is greater than an angle between the second
direction and the first direction, from after a portion that will
have the bent shape passes through the molten metal passage portion
until the portion that will have the bent shape reaches a
solidification interface, and then drawing up the molten metal.
2. The up-drawing continuous casting method according to claim 1,
wherein the third direction is determined such that a direction in
which the portion that will have the bent shape heads toward the
solidification interface from the molten metal passage portion,
when the portion that will have the bent shape reaches the
solidification interface, comes to match the second direction.
3. The up-drawing continuous casting method according to claim 1,
further comprising: changing the up-drawing direction to the second
direction and drawing up the molten metal, after the portion that
will have the bent shape reaches the solidification interface.
4. The up-drawing continuous casting method according to claim 1,
wherein the up-drawing direction is changed to the third direction
and the molten metal is drawn up, when the portion that will have
the bent shape is midway between the molten metal passage portion
and the solidification interface, or is closer to the
solidification interface than midway between the molten metal
passage portion and the solidification interface.
Description
INCORPORATION BY REFERENCE
[0001] The disclosure of Japanese Patent Application No.
2014-046047 filed on Mar. 10, 2014 including the specification,
drawings and abstract is incorporated herein by reference in its
entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The invention relates to an up-drawing continuous casting
method.
[0004] 2. Description of Related Art
[0005] Japanese Patent Application Publication No. 2012-61518 (JP
2012-61518 A) proposes a free casting method as a groundbreaking
up-drawing continuous casting method that does not require a mold.
As described in JP 2012-61518 A, a starter is first dipped into the
surface of molten metal (a molten metal surface), and then when the
starter is drawn up, molten metal is also drawn up following the
starter by surface tension and the surface film of the molten
metal. Here, a casting that has a desired sectional shape is able
to be continuously cast by drawing up the molten metal through a
shape determining member arranged near the molten metal surface,
and cooling the drawn up molten metal.
[0006] With a normal continuous casting method, the sectional shape
and the shape in the longitudinal direction are both determined by
a mold. In particular, with a continuous casting method, the
solidified metal (i.e., the casting) must pass through the mold, so
the cast casting takes on a shape that extends linearly in the
longitudinal direction.
[0007] In contrast, the shape determining member in the free
casting method determines only the sectional shape of the casting.
The shape in the longitudinal direction is not determined.
Therefore, castings of various shapes in the longitudinal direction
are able to be obtained by drawing the starter up while moving the
starter (or the shape determining member) in a horizontal
direction. For example, JP 2012-61518 A describes a hollow casting
(i.e., a pipe) formed in a zigzag shape or a helical shape, not a
linear shape in the longitudinal direction.
[0008] The inventors discovered the problem described below. With
the free casting method described in JP 2012-61518 A, the molten
metal drawn up through the shape determining member is cooled and
solidified by cooling gas, so a solidification interface is
positioned above the shape determining member. Therefore, when
forming a bent shape in the casting by changing the up-drawing
direction of the molten metal, the molten metal solidifies after
the change in the up-drawing direction. Therefore, the molten metal
drawn up before the change in the up-drawing direction ends up
being drawn to the molten metal drawn up after the change in the
up-drawing direction, and as a result, the bent shape ends up
becoming rounded. As a result, a bent shape having a predetermined
bending angle is unable to be formed in the casting, which is
problematic.
SUMMARY OF THE INVENTION
[0009] In view of this, the invention aims to provide an up-drawing
continuous casting method capable of forming a bent shape having a
predetermined angle in a cast casting.
[0010] One aspect of the invention relates to an up-drawing
continuous casting method for forming a bent shape in a cast
casting by forming the casting in a first direction and then
changing an up-drawing direction to a second direction and forming
the casting in the second direction, the casting being formed by
drawing up molten metal held in a holding furnace from a molten
metal surface of the molten metal, passing the molten metal through
a molten metal passage portion of a shape determining member that
determines a sectional shape of the casting, and solidifying the
molten metal. This up-drawing continuous casting method includes a
step of drawing up the molten metal in the first direction; and a
step of changing the up-drawing direction to a third direction in
which an angle between the third direction and the first direction
is greater than an angle between the second direction and the first
direction, from after a portion that will have the bent shape
passes through the molten metal passage portion until the portion
that will have the bent shape reaches a solidification interface,
and then drawing up the molten metal. The up-drawing continuous
casting method according to this aspect of the invention changes
the up-drawing direction of the molten metal after the portion that
will have the bent shape moves close to the solidification
interface. Therefore, the majority of the molten metal drawn up
before the portion that will have the bent shape is already
solidified when the up-drawing direction of the molten metal
changes, so a constant shape is able to be maintained without being
affected by the molten metal drawn up after the change in the
up-drawing direction. As a result, rounding of the bent shape is
able to be suppressed. Also, the up-drawing direction is changed to
the third direction in which the angle between the third direction
and the first direction is greater than the angle between the
second direction and the first direction, and then the molten metal
is drawn up. Accordingly, the extending direction of the retained
molten metal is able to be aligned with the second direction in a
short period of time from after the up-drawing direction of the
molten metal is changed until the portion that will have the bent
shape reaches the solidification interface. As a result, a bent
shape having a predetermined bending angle is able to be formed in
the casting.
[0011] The invention thus makes it possible to provide an
up-drawing continuous casting method capable of forming a bent
shape having a predetermined angle in a cast casting.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] Features, advantages, and technical and industrial
significance of exemplary embodiments of the invention will be
described below with reference to the accompanying drawings, in
which like numerals denote like elements, and wherein:
[0013] FIG. 1 is a sectional view showing a frame format of a free
casting apparatus according to a first example embodiment of the
invention;
[0014] FIG. 2 is a plan view of a shape determining member
according to the first example embodiment;
[0015] FIG. 3 is a sectional view of one example of a molded
component of a casting;
[0016] FIG. 4 is a view illustrating a free casting method
according to the first example embodiment;
[0017] FIG. 5 is a view illustrating a casting method of a casting
according to related art;
[0018] FIG. 6 is a sectional view of another example of a molded
component of a casting;
[0019] FIG. 7 is a view illustrating a free casting method
according to the first example embodiment;
[0020] FIG. 8 is a view illustrating a casting method of a casting
according to related art;
[0021] FIG. 9 is an image showing casting results of the
castings;
[0022] FIG. 10 is a plan view of a shape determining member
according to a second example embodiment of the invention; and
[0023] FIG. 11 is a side view of the shape determining member
according to the second example embodiment.
DETAILED DESCRIPTION OF EMBODIMENTS
[0024] Hereinafter, specific example embodiments to which the
invention has been applied will be described in detail with
reference to the accompanying drawings. However, the invention is
not limited to these example embodiments. Also, the description and
the drawings are simplified as appropriate to clarify the
description.
First Example Embodiment
[0025] First, a free casting apparatus (up-drawing continuous
casting apparatus) according to a first example embodiment of the
invention will be described with reference to FIG. 1. FIG. 1 is a
sectional view showing a frame format of the free casting apparatus
according to the first example embodiment. As shown in FIG. 1, the
free casting apparatus according to the first example embodiment
includes a molten metal holding furnace 101, a shape determining
member 102, a support rod 104, an actuator 105, a cooling gas
nozzle 106, a cooling gas supplying portion 107, and an up-drawing
machine 108. In FIG. 1, a right-handed xyz coordinate system is
shown for descriptive purposes to illustrate the positional
relationship of the constituent elements. The x-y plane in FIG. 1
forms a horizontal plane, and the z-axis direction is the vertical
direction. More specifically, the plus direction of the z-axis is
vertically upward.
[0026] The molten metal holding furnace 101 holds molten metal M1
such as aluminum or an aluminum alloy, for example, and keeps it at
a predetermined temperature at which the molten metal M1 has
fluidity. In the example in FIG. 1, molten metal is not replenished
into the molten metal holding furnace 101 during casting, so the
surface of the molten metal M1 (i.e., the molten metal surface
level) drops as casting proceeds. However, molten metal may also be
replenished into the molten metal holding furnace 101 when
necessary during casting so that the molten metal surface level is
kept constant. Here, the position of a solidification interface SIF
can be raised by increasing a set temperature of the molten metal
holding furnace 101, and lowered by reducing the set temperature of
the molten metal holding furnace 101. Naturally, the molten metal
M1 may be another metal or alloy other than aluminum.
[0027] The shape determining member 102 is made of ceramic or
stainless steel, for example, and is arranged above the molten
metal M1. The shape determining member 102 determines the sectional
shape of a cast casting M3. The casting M3 shown in FIG. 1 is a
solid casting (a plate) having a rectangular cross-section in the
horizontal direction (hereinafter, simply referred to as
"transverse section"). Naturally, the sectional shape of the
casting M3 is not particularly limited. That is, the casting M3 may
also be a hollow casting of a round pipe or a square pipe or the
like.
[0028] In the example in FIG. 1, a main surface (a lower surface)
on a lower side of the shape determining member 102 is arranged
contacting the molten metal surface. Therefore, an oxide film that
forms on the surface of the molten metal M1 and foreign matter
floating on the surface of the molten metal M1 are able to be
prevented from getting mixed into the casting M3. However, the
lower surface of the shape determining member 102 may also be
arranged a predetermined distance away from the molten metal
surface. When the shape determining member 102 is arranged away
from the molten metal surface, heat deformation and erosion of the
shape determining member 102 are inhibited, so the durability of
the shape determining member 102 improves.
[0029] FIG. 2 is a plan view of the shape determining member 102
according to the first example embodiment. Here, the sectional view
of the shape determining member 102 in FIG. 1 corresponds to a
sectional view taken along line I-I in FIG. 2. As shown in FIG. 2,
the shape determining member 102 has a rectangular planar shape,
for example, and has a rectangular open portion (a molten metal
passage portion 103) having a thickness t1 and a width w1 through
which the molten metal passes in the center portion. The xyz
coordinates in FIG. 2 match those in FIG. 1.
[0030] As shown in FIG. 1, after joining with a starter ST that has
been dipped into the molten metal M1, the molten metal M1 is drawn
up following the starter ST while maintaining its outer shape, by
the surface tension and the surface film of the molten metal M1,
and passes through the molten metal passage portion 103 of the
shape determining member 102. By passing the molten metal M1
through the molten metal passage portion 103 of the shape
determining member 102, external force is applied to the molten
metal M1 from the shape determining member 102, such that the
sectional shape of the casting M3 is determined. Here, the molten
metal that is drawn up from the molten metal surface following the
starter ST (or the casting M3 formed by the molten metal M1 drawn
up following the starter ST solidifying) by the surface film and
the surface tension of the molten metal M1 will be referred to as
"retained molten metal M2". Also, the boundary between the casting
M3 and the retained molten metal M2 is a solidification interface
SIF.
[0031] The support rod 104 supports the shape determining member
102. The support rod 104 is connected to the actuator 105. The
shape determining member 102 is able to move up and down (i.e., in
the vertical direction; the z-axis direction) via the support rod
104, by the actuator 105. According to this kind of structure, the
shape determining member 102 is able to be moved downward as the
molten metal surface level drops as casting proceeds.
[0032] A cooling gas nozzle (a cooling portion) 106 is cooling
means for spraying cooling gas (e.g., air, nitrogen, argon, or the
like) supplied from the cooling gas supplying portion 107 at the
casting M3 to cool the casting M3. The position of the
solidification interface SIF is able to be lowered by increasing
the flow rate of the cooling gas, and raised by reducing the flow
rate of the cooling gas. The cooling gas nozzle 106 is also able to
be moved up and down (i.e., in the vertical direction; in the
z-axis direction) and horizontally (i.e., in the x-axis direction
and the y-axis direction). Therefore, for example, the cooling gas
nozzle 106 can be moved downward, in concert with the movement of
the shape determining member 102, as the molten metal surface level
drops as casting proceeds.
[0033] Alternatively, the cooling gas nozzle 106 can be moved
horizontally, in concert with horizontal movement of the up-drawing
machine 108.
[0034] The casting M3 is formed by the retained molten metal M2
near the solidification interface SIF progressively solidifying
from the upper side (i.e., the plus side in the z-axis direction)
toward lower side (i.e., the minus side in the z-axis direction),
by cooling the starter ST and the casting M3 with the cooling gas,
while drawing the casting M3 up with the up-drawing machine 108
that is connected to the starter ST. The position of the
solidification interface SIF is able to be raised by increasing the
up-drawing speed with the up-drawing machine 108, and lowered by
reducing the up-drawing speed. Also, the retained molten metal M2
is able to be drawn up diagonally by drawing the casting M3 up
while moving the up-drawing machine 108 horizontally (in the x-axis
direction and the y-axis direction). Therefore, the longitudinal
shape of the casting M3 is able to be freely changed. The
longitudinal shape of the casting M3 may also be freely changed by
moving the shape determining member 102 horizontally, instead of by
moving the up-drawing machine 108 horizontally.
[0035] Continuing on, a free casting method according to the
example embodiment will be described with reference to FIG. 1.
[0036] First, the starter ST is lowered by the up-drawing machine
108 so that it passes through the molten metal passage portion 103
of the shape determining member 102, and the tip end portion of the
starter ST is dipped into the molten metal M1.
[0037] Next, the starter ST starts to be drawn up at a
predetermined speed. Here, even if the starter ST separates from
the molten metal surface, the molten metal M1 follows the starter
ST and is drawn up from the molten metal surface by the surface
film and surface tension, and forms the retained molten metal M2.
As shown in FIG. 1, the retained molten metal M2 is formed in the
molten metal passage portion 103 of the shape determining member
102. That is, the shape determining member 102 gives the retained
molten metal M2 its shape.
[0038] Next, the starter ST (or the casting M3 formed by the
retained molten metal M2 solidifying) is cooled by cooling gas
blown from the cooling gas nozzle 106. As a result, the retained
molten metal M2 is indirectly cooled and solidifies progressively
from the upper side toward the lower side, thus forming the casting
M3. In this way, the casting M3 is able to be continuously
cast.
[0039] Here, a bent shape is able to be formed in the casting M3 by
changing the up-drawing direction of the molten metal M1. This will
be described in detail below.
[0040] FIG. 3 is a sectional view of an example of a molded
component of the casting M3 cast by the free casting apparatus
shown in FIG. 1. The xyz coordinates in FIG. 3 match those in FIG.
1.
[0041] With the molded component of the casting M3 shown in FIG. 3,
after portions (1 and 2 is in the drawing; hereinafter, also
referred to as castings M3_1 and M3_2) of the molded component are
formed in the vertical direction (i.e., the z-axis direction;
hereinafter referred to as a "first direction"), then other
portions (3 and 4 is in the drawing; hereinafter, also referred to
also as castings M3_3 and M3_4) of the molded component are formed
in a direction (i.e., the z-axis direction; hereinafter, also
referred to as a "second direction") inclined toward the x-axis
direction plus side by an angle .theta.1 with respect to the first
direction. Here, a bent shape having a predetermined bending angle
a is formed near the boundary between the castings M3_2 and M3_3.
The angle .theta.1 is .alpha. supplementary angle to the angle
.alpha..
[0042] FIG. 4 is a view illustrating the free casting method of the
molded component of the casting M3 shown in FIG. 3. The xyz
coordinates in FIG. 4 match those in FIG. 1. Hereinafter, a case in
which the up-drawing speed and cooling conditions of the molten
metal M1 are constant, will be described in order to simplify the
description. Therefore, the solidification interface is also
constant.
[0043] First, the retained molten metal M2 (1 and 2 in the drawing;
hereinafter, also referred to as retained molten metals M2_1 and
M2_2) that extends in the first direction is progressively formed
by continuously drawing up the molten metal M1 in the first
direction (time t0 to t2).
[0044] Then, by drawing up the molten metal M1 in the first
direction, a retained molten metal M2_3 (3 in the drawing) that
extends in the first direction is formed after the retained molten
metals M2_1 and M2_2 are formed (time t2 to t3). At this time, the
retained molten metal M2_1 reaches the solidification interface and
thus solidifies, forming the casting M3_1 that extends in the first
direction (time t2 to t3). At time t2 to t3, the up-drawing
direction of the retained molten metal M2_3 remains the first
direction, just like the retained molten metals M2_1 and M2_2. That
is, at time t2 to t3, a portion that will have the bent shape (near
the boundary between the retained molten metals M2_2 and M2_3) does
not have the bent shape. Therefore, the retained molten metal M2_1
is able to solidify without being drawing by the retained molten
metals M2_2 and M2_3 and changing shape.
[0045] Then, as the portion that will have the bent shape moves
close to the solidification interface, the up-drawing direction is
changed to a direction (hereinafter, referred to as a "third
direction") inclined toward the x-axis direction plus side by an
angle .theta.2 (.theta.2>.theta.1) with respect to the first
direction, and the molten metal M1 starts to be drawn up (time t3).
In the example in FIG. 4, when the portion that will have the bent
shape is positioned midway between the molten metal passage portion
103 and the solidification interface, the up-drawing direction
changes from the first direction to the third direction, and the
molten metal M1 starts to be drawn up (time t3). As a result, a
retained molten metal M2_4 that extends in the third direction
(i.e., the region 4 surrounded by the dotted lines in the drawing)
is formed (time t3 to t4). Here, the retained molten metal M2_3
formed in the first direction (i.e., the region surrounded by the
dotted lines in the drawing) has not yet solidified, and is drawn
by the retained molten metal M2_4 formed in the third direction
(i.e., the region surrounded by the dotted lines in the drawing),
thus changing shape, and being formed extending along a line
portion that connects the molten metal passage portion 103 to the
solidification interface, together with the retained molten metal
M2_4 (i.e., the region surrounded by the solid lines in the
drawing). The value of the angle .theta.2 is set such that the
direction in which the portion that will have the bent shape heads
toward the solidification interface from the molten metal passage
portion 103, i.e., the extending direction of the retained molten
metals M2_3 and M2_4, when the portion that will have the bent
shape reaches the solidification interface, comes to match the
second direction.
[0046] Also, at this time, the retained molten metal M2_2 reaches
the solidification interface, so it solidifies, forming the casting
M3_2 that extends in the first direction (time t3 to t4). Here, as
described above, the up-drawing direction of the molten metal M1 is
changed after the portion that will have the bent shape moves close
to the solidification interface, so the casting M3_1 will of course
not be drawn by the retained molten metal M2 and thus will not
change shape. What is more, the retained molten metal M2_2 will
also solidify either before being drawn by the retained molten
metals M2_3 and M2_4 and changing shape, or while that effect is
still small. As a result, the desired casting M3_2 that extends in
the first direction is able to be formed.
[0047] After the portion that will have the bent shape has reached
the solidification interface, the up-drawing direction is changed
to the second direction, which is the forming direction of the
castings M3_3 and M3_4, and the molten metal M1 is drawn up (time
t4 to t6). At this time, the retained molten metals M2_3 and M2_4
reach the solidification interface, so they solidifies while
maintaining a shape that extends in the second direction, thus
forming the castings M3_3 and M3_4.
[0048] As a result, a molded component of the casting M3 is able to
be formed, the molded component of the casting M3 is formed by the
castings M3_1 and M3_2 that extend in the first direction, and the
castings M3_3 and M3_4 that extend in the second direction, and
molded component of the casting M3 has a bent shape of a
predetermined bending angle .alpha..
[0049] FIG. 5 is a view illustrating a casting method of the
casting M3 according to related art, as a comparative example of
FIG. 4. In the example in FIG. 5, the up-drawing direction of the
molten metal M1 is changed from the first direction to the second
direction at the same time that the portion that will have the bent
shape (near the boundary between the retained molten metals M2_2
and M2_3) reaches the molten metal passage portion 103 (time t2).
However, the retained molten metal M2 solidifies after the change
in the up-drawing direction of the molten metal M1. Therefore, the
molten metal drawn up before the change in the up-drawing direction
(i.e., the retained molten metals M2_1 and M2_2) will end up being
drawn by the molten metal drawn up after the change in the
up-drawing direction (i.e., the retained molten metal M2_3), so the
bent shape will end up being rounded. As a result, a bent shape
having a predetermined angle is unable to be formed in the
casting.
[0050] In contrast, with the up-drawing continuous casting method
according to this example embodiment shown in FIG. 4, the
up-drawing direction of the molten metal M1 is changed after the
portion that will have the bent shape moves close to the
solidification interface. Therefore, the majority (or at least more
than that in FIG. 5) of the molten metal M1 drawn up before the
portion that will have the bent shape is already solidified when
the up-drawing direction of the molten metal M1 changes, so a
constant shape is able to be maintained without being affected by
the molten metal M1 drawn up after the change in the up-drawing
direction. As a result, rounding of the bent shape is able to be
suppressed. Also, the up-drawing direction is changed to the third
direction in which the angle between the third direction and the
first direction is greater than the angle between the second
direction and the first direction, and then the molten metal M1 is
drawn up. Accordingly, the extending direction of the retained
molten metal M2 is able to be aligned with the second direction in
a short period of time from after the up-drawing direction of the
molten metal M1 is changed until the portion that will have the
bent shape reaches the solidification interface. As a result, a
bent shape having a predetermined bending angle is able to be
formed in the casting M3.
[0051] FIG. 6 is a sectional view of another example of a molded
component of the casting M3 cast with the free casting apparatus
shown in FIG. 1. The xyz coordinates in FIG. 6 match those in FIG.
1.
[0052] With the molded component of the casting M3 shown in FIG. 6,
portions (castings M3_1 and M3_2) of the molded component are first
formed in a direction inclined toward the x-axis direction plus
side (hereinafter, simply referred to as the "first direction") by
an angle .theta.1 with respect to the vertical direction (the
z-axis direction; hereinafter simply referred to as the "second
direction"), and then other portions (castings M3_3 and M3_4) of
the molded component are formed in the second direction. Here, a
bent shape having a predetermined bending angle .alpha. is formed
near the boundary between the castings M3_2 and M3_3.
[0053] FIG. 7 is a view illustrating a free casting method of the
molded component of the casting M3 shown in FIG. 6. The xyz
coordinates in FIG. 7 match those in FIG. 1. The free casting
method shown in FIG. 7 is basically the same as the free casting
method shown in FIG. 4, except that the orientations of the first
direction and the second direction are different, so a description
thereof will be omitted. FIG. 8 is a view illustrating a casting
method of the casting M3 according to related art, as a comparative
example of FIG. 7. FIG. 8 is also basically the same as FIG. 5,
except that the orientations of the first direction and the second
direction are different, so a description thereof will be
omitted.
[0054] FIG. 9 is an image of a cross-section of the casting M3 cast
according to the free casting method according to this example
embodiment. FIG. 9 also shows an image of a cross-section of the
casting M3 cast according to the casting method of the related art,
as a comparative example. As shown in FIG. 9, it is evident that
the bent shape of the casting M3 cast according to the casting
method of the related art is rounded, while the bent shape of the
casting M3 cast according to the free casting method of this
example embodiment is not rounded.
[0055] In this way, with the free casting method according to this
example embodiment, the up-drawing direction of the molten metal M1
is changed after the portion that will have the bent shape moves
close to solidification interface. As a result, the majority of the
molten metal M1 drawn up before the portion that will have the bent
shape is already solidified when the up-drawing direction of the
molten metal M1 changes, so a constant shape is able to be
maintained without being affected by the molten metal M1 drawn up
after the change in the up-drawing direction. As a result, rounding
of the bent shape is able to be suppressed. Also, the up-drawing
direction is changed to the third direction in which the angle
between the third direction and the first direction is greater than
the angle between the second direction and the first direction, and
then the molten metal M1 is drawn up. Accordingly, the extending
direction of the retained molten metal M2 is able to be aligned
with the second direction (i.e., the molding direction of the
casting M3) in a short period of time from after the up-drawing
direction of the molten metal M1 is changed until the portion that
will have the bent shape reaches the solidification interface. As a
result, a bent shape having a predetermined bending angle is able
to be formed in the casting M3.
[0056] In this example embodiment, a case in which the up-drawing
direction of the molten metal M1 is changed when the portion that
will have the bent shape is positioned midway between the molten
metal passage portion 103 and the solidification interface has been
described, but the example embodiment is not limited to this. The
timing at which the up-drawing direction of the molten metal M1 is
changed may any time from after the portion that will have the bent
shape passes through the molten metal passage portion 103 until it
reaches the solidification interface. However, the value of the
angle .theta.2 must be adjusted such that the direction in which
the portion that will have the bent shape heads toward the
solidification interface from the molten metal passage portion 103,
when the portion that will have the bent shape reaches the
solidification interface, comes to match the second direction. For
example, a bent shape is able to be made in the casting M3 more
accurately the closer the timing at which the up-drawing direction
of the molten metal M1 changes is to when the portion that will
have the bent shape is near the solidification interface. On the
other hand, the change in the up-drawing direction of the molten
metal M1 becomes smaller the closer the timing at which the
up-drawing direction of the molten metal M1 changes is to when the
portion that will have the bent shape is near the molten metal
passage portion 103, so the retained molten metal M2 is able to be
prevented from being torn or the like by the change in the
up-drawing direction. The up-drawing direction of the molten metal
M1 is preferably changed when the portion that will have the bent
shape is midway between the molten metal passage portion 103 and
the solidification interface, or closer to the solidification
interface than midway between the molten metal passage portion 103
and the solidification interface.
[0057] Also, in this example embodiment, an example in which the
up-drawing direction of the molten metal M1 is changed only once to
form one bent shape in the casting M3 is described, but the example
embodiment is not limited to this. The up-drawing direction of the
molten metal M1 may also be changed two or more times to form one
bent shape in the casting M3.
Second Example Embodiment
[0058] Next, a free casting apparatus according to a second example
embodiment of the invention will be described with reference to
FIGS. 10 and 11. FIG. 10 is a plan view of a shape determining
member 202 according to the second example embodiment. FIG. 11 is a
side view of the shape determining member 202 according to the
second example embodiment. The xyz coordinates in FIGS. 10 and 11
also match those in FIG. 1.
[0059] The shape determining member 102 according to the first
example embodiment shown in FIG. 2 is made of a single plate, so
the thickness t1 and the width w1 of the molten metal passage
portion 103 are fixed. In contrast to this, the shape determining
member 202 according to the second example embodiment includes four
rectangular shape determining plates 202a, 202b, 202c, and 202d, as
shown in FIG. 10. That is, the shape determining member 202 is
divided into a plurality of sections. This kind of structure
enables the thickness t1 and the width w1 of a molten metal passage
portion 203 to be changed. Also, the four rectangular shape
determining plates 202a, 202b, 202c, and 202d are able to move
synchronously in the z-axis direction.
[0060] As shown in FIG. 10, the shape determining plates 202a and
202b are arranged facing each other lined up in the y-axis
direction. Also, as shown in FIG. 11, the shape determining plates
202a and 202b are arranged at the same height in the z-axis
direction. The distance between the shape determining plates 202a
and 202b determines the width w1 of the molten metal passage
portion 203. Also, the shape determining plates 202a and 202b are
able to move independently in the y-axis direction, so they are
able to change the width w1. A laser displacement gauge S1 may be
provided on the shape determining plate 202a, and a laser
reflecting plate S2 may be provided on the shape determining plate
202b, as shown in FIGS. 10 and 11, in order to measure the width w1
of the molten metal passage portion 203.
[0061] Also, as shown in FIG. 10, the shape determining plates 202c
and 202d are arranged facing each other lined up in the x-axis
direction. Also, the shape determining plates 202c and 202d are
arranged at the same height in the z-axis direction. The distance
between the shape determining plates 202c and 202d determines the
thickness t1 of the molten metal passage portion 203. Also, the
shape determining plates 202c and 202d are able to move
independently in the x-axis direction, so they are able to change
the thickness t1. The shape determining plates 202a and 202b are
arranged contacting upper sides of the shape determining plates
202c and 202d.
[0062] Next, the drive mechanism of the shape determining plate
202a will be described with reference to FIGS. 10 and 11. As shown
in FIGS. 10 and 11, the drive mechanism of the shape determining
plate 202a includes slide tables T1 and T2, linear guides G11, G12,
G21, and G22, actuators A1 and A2, and rods R1 and R2. The shape
determining plates 202b, 202c, and 202d also each include a drive
mechanism, similar to the shape determining plate 202a, but these
are not shown in FIGS. 10 and 11.
[0063] As shown in FIGS. 10 and 11, the shape determining plate
202a is placed on and fixed to the slide table T1 that is able to
slide in the y-axis direction. The slide table T1 is slidably
placed on the pair of linear guides G11 and G12 that extend
parallel to the y-axis direction. Also, the slide table T1 is
connected to the rod R1 that extends in the y-axis direction from
the actuator A1. This kind of structure enables the shape
determining plate 202a to slide in the y-axis direction.
[0064] Also, as shown in FIGS. 10 and 11, the linear guides G11 and
G12, and the actuator A1, are placed on and fixed to the slide
table T2 that is able to slide in the z-axis direction. The slide
table T2 is slidably placed on the pair of linear guides G21 and
G22 that extend parallel to the z-axis direction. Also, the slide
table T2 is connected to the rod R2 that extends in the z-axis
direction from the actuator A2. The linear guides G21 and G22, and
the actuator A2, are fixed to a horizontal floor or base, not
shown, or the like. This kind of structure enables the shape
determining plate 202a to slide in the z-axis direction. The
actuators A1 and A2 may be hydraulic cylinders, air cylinders, or
electric motors or the like, for example. The other structure is
the same as that of the first example embodiment, so a description
thereof will be omitted.
[0065] With the free casting method according to the second example
embodiment, effects similar to those of the first example
embodiment are able to be displayed. In addition, the thickness t1
and width w1 of the molten metal passage portion 203 of the shape
determining member 202 are able to be changed. Therefore, the
dimensions (the thickness t and the width w) of the casting are
able to be freely changed.
[0066] The invention is not limited to the example embodiments
described above, and may be modified as appropriate without
departing from the spirit of the invention.
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