U.S. patent application number 14/908844 was filed with the patent office on 2016-06-30 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 Masafumi NISHIDA, Naoaki SUGIURA, Yuto TANAKA, TOYOTA JIDOSHA KABUSHIKI KAISHA, Yusuke YOKOTA. Invention is credited to Masafumi NISHIDA, Naoaki SUGIURA, Yuto TANAKA, Yusuke YOKOTA.
Application Number | 20160184885 14/908844 |
Document ID | / |
Family ID | 52431262 |
Filed Date | 2016-06-30 |
United States Patent
Application |
20160184885 |
Kind Code |
A1 |
YOKOTA; Yusuke ; et
al. |
June 30, 2016 |
PULLING-UP-TYPE CONTINUOUS CASTING APPARATUS AND PULLING-UP-TYPE
CONTINUOUS CASTING METHOD
Abstract
A pulling-up-type continuous casting apparatus according to the
present invention includes a molten-metal holding furnace (101)
that holds molten metal (M1), a starter (ST) that draws the molten
metal (M1) held in the molten-metal holding furnace (101) from a
molten-metal surface of the molten metal (M1), and a shape defining
member (102) that defines a cross-sectional shape of a cast-metal
article (M3) to be cast by applying an external force to the held
molten metal (M2) drawn by the starter (ST), in which the starter
(ST) includes a body part (107) and a tip part (108), the tip part
(108) including a tip (109) having a horizontal cross section
smaller than that of the body part (107).
Inventors: |
YOKOTA; Yusuke; (Toyota-shi,
JP) ; NISHIDA; Masafumi; (Okazaki-shi, JP) ;
SUGIURA; Naoaki; (Takahama-shi,, JP) ; TANAKA;
Yuto; (Toyota-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
YOKOTA; Yusuke
NISHIDA; Masafumi
SUGIURA; Naoaki
TANAKA; Yuto
TOYOTA JIDOSHA KABUSHIKI KAISHA |
Aichi
Aichi
Aichi
Aichi
Toyota-shi |
|
JP
JP
JP
JP
JP |
|
|
Assignee: |
TOYOTA JIDOSHA KABUSHIKI
KAISHA
Toyota-shi, Aichi
JP
|
Family ID: |
52431262 |
Appl. No.: |
14/908844 |
Filed: |
June 16, 2014 |
PCT Filed: |
June 16, 2014 |
PCT NO: |
PCT/JP2014/003205 |
371 Date: |
January 29, 2016 |
Current U.S.
Class: |
164/479 ;
164/425 |
Current CPC
Class: |
B22D 11/145 20130101;
B22D 11/06 20130101; B22D 11/083 20130101 |
International
Class: |
B22D 11/06 20060101
B22D011/06; B22D 11/14 20060101 B22D011/14; B22D 11/08 20060101
B22D011/08 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 30, 2013 |
JP |
2013-158205 |
Claims
1. A pulling-up-type continuous casting apparatus comprising: a
holding furnace that holds molten metal; a drawing member that
draws the molten metal held in the holding furnace from a
molten-metal surface of the molten metal; and a shape defining
member that defines a cross-sectional shape of a cast-metal article
to be cast by applying an external force to the molten metal drawn
by the drawing member, wherein the drawing member comprises a body
part and a tip part, the tip part comprising a tip having a
horizontal cross section smaller than that of the body part.
2. The pulling-up-type continuous casting apparatus according to
claim 1, wherein the tip part has a tapered shape such that the tip
part becomes narrower toward its tip.
3. The pulling-up-type continuous casting apparatus according to
claim 2, wherein the angle of the tip is 45 degrees or smaller.
4. The pulling-up-type continuous casting apparatus according to
claim 1, wherein the tip part comprises a plurality of tips.
5. The pulling-up-type continuous casting apparatus according to
claim 1, wherein the drawing member further comprises at least one
of a first protrusion part protruding from a side of the tip part
or the body part and a first recessed part recessed from the side
of the tip part or the body part.
6. The pulling-up-type continuous casting apparatus according to
claim 5, wherein the protrusion length of the first protrusion part
or the recess depth of the first recessed part is 1 mm or
larger.
7. The pulling-up-type continuous casting apparatus according to
claim 5, wherein the drawing member comprises a plurality of first
protrusion parts or a plurality of first recessed parts.
8. The pulling-up-type continuous casting apparatus according to
claim 1, wherein the tip part further comprises: an opening opened
from the tip; and at least one of a second protrusion part
protruding from a side of the opening and a second recessed part
recessed from the side of the opening.
9. The pulling-up-type continuous casting apparatus according to
claim 8, wherein the protrusion length of the second protrusion
part or the recess depth of the second recessed part is 1 mm or
larger.
10. The pulling-up-type continuous casting apparatus according to
claim 8, wherein the tip part comprises a plurality of second
protrusion parts or a plurality of second recessed parts.
11. A pulling-up-type continuous casting apparatus comprising: a
holding furnace that holds molten metal; a drawing member that
draws the molten metal held in the holding furnace from a
molten-metal surface of the molten metal; and a shape defining
member that defines a cross-sectional shape of a cast-metal article
to be cast by applying an external force to the molten metal drawn
by the drawing member, wherein the drawing member comprises a body
part, and at least one of a first protrusion part protruding from a
side of the body part and a first recessed part recessed from the
side of the body part.
12. The pulling-up-type continuous casting apparatus according to
claim 11, wherein the protrusion length of the first protrusion
part or the recess depth of the first recessed part is 1 mm or
larger.
13. The pulling-up-type continuous casting apparatus according to
claim 11, wherein the drawing member comprises a plurality of first
protrusion parts or a plurality of first recessed parts.
14. The pulling-up-type continuous casting apparatus according to
claim 11, wherein the body part further comprises: an opening
opened from the tip; and at least one of a second protrusion part
protruding from a side of the opening and a second recessed part
recessed from the side of the opening.
15. The pulling-up-type continuous casting apparatus according to
claim 14, wherein the protrusion length of the second protrusion
part or the recess depth of the second recessed part is 1 mm or
larger.
16. The pulling-up-type continuous casting apparatus according to
claim 14, wherein the body part comprises a plurality of second
protrusion parts or a plurality of second recessed parts.
17. A pulling-up-type continuous casting method comprising: a step
of submerging a drawing member into a molten-metal surface of
molten metal held in a holding furnace; and a step of drawing the
molten metal by the drawing member and making the drawn 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, wherein the drawing member is formed
from a body part and a tip part, the tip part comprising a tip
having a horizontal cross section smaller than that of the body
part.
18.-26. (canceled)
27. A pulling-up-type continuous casting method comprising: a step
of submerging a drawing member into a molten-metal surface of
molten metal held in a holding furnace; and a step of drawing the
molten metal by the drawing member and making the drawn 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, wherein the drawing member is formed
from a body part, and at least one of a first protrusion part
protruding from a side of the body part and a first recessed part
recessed from the side of the body part.
28-32. (canceled)
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] The inventors of the present application have proposed, in
Patent Literature 1, a free casting method as a revolutionary
continuous casting method that does not requires any mold. 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 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 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.
Namely, in the free casting method disclosed in Patent Literature
1, there is a problem that the molten-metal drawing property of the
starter is unsatisfactory.
[0007] 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 and a pulling-up-type
continuous casting method capable of improving the molten-metal
drawing property of the starter by contriving (or designing) the
shape of the starter.
Solution to Problem
[0008] A pulling-up-type continuous casting apparatus according to
an aspect of the present invention includes: a holding furnace that
holds molten metal; a drawing member that draws the molten metal
held in the holding furnace from a molten-metal surface of the
molten metal; and a shape defining member that defines a
cross-sectional shape of a cast-metal article to be cast by
applying an external force to the molten metal drawn by the drawing
member, in which the drawing member includes a body part and a tip
part, the tip part including a tip having a horizontal cross
section smaller than that of the body part. As a result, it is
possible to submerge the starter (drawing member) by making the
starter (drawing member) break through an oxide film formed on the
molten-metal surface of the molten metal, thus improving the
molten-metal drawing property of the starter.
[0009] The tip part preferably has a tapered shape such that the
tip part becomes narrower toward its tip.
[0010] The angle of the tip is preferably 45 degrees or
smaller.
[0011] The tip part preferably includes a plurality of tips.
[0012] The drawing member preferably further includes at least one
of a first protrusion part protruding from a side of the tip part
or the body part and a first recessed part recessed from the side
of the tip part or the body part.
[0013] The protrusion length of the first protrusion part or the
recess depth of the first recessed part is preferably 1 mm or
larger.
[0014] The drawing member preferably includes a plurality of first
protrusion parts or a plurality of first recessed parts.
[0015] The tip part preferably further includes an opening opened
from the tip, and at least one of a second protrusion part
protruding from a side of the opening and a second recessed part
recessed from the side of the opening.
[0016] The protrusion length of the second protrusion part or the
recess depth or the second recessed part is preferably 1 mm or
larger.
[0017] The tip part preferably includes a plurality of second
protrusion parts or a plurality of second recessed parts.
[0018] A pulling-up-type continuous casting apparatus according to
another aspect of the present invention includes: a holding furnace
that holds molten metal; a drawing member that draws the molten
metal held in the holding furnace from a molten-metal surface of
the molten metal; and a shape defining member that defines a
cross-sectional shape of a cast-metal article to be cast by
applying an external force to the molten metal drawn by the drawing
member, in which the drawing member includes a body part, and at
least one of a first protrusion part protruding from a side of the
body part and a first recessed part recessed from the side of the
body part. As a result, it is possible to improve the bonding force
between the starter (drawing member) and the molten metal, thus
improving the molten-metal drawing property of the starter.
[0019] The protrusion length of the first protrusion part or the
recess depth of the first recessed part is preferably 1 mm or
larger.
[0020] The drawing member preferably includes a plurality of first
protrusion parts or a plurality of first recessed parts.
[0021] The body part preferably further includes an opening opened
from the tip, and at least one of a second protrusion part
protruding from a side of the opening and a second recessed part
recessed from the side of the opening.
[0022] The protrusion length of the second protrusion part or the
recess depth of the second recessed part is preferably 1 mm or
larger.
[0023] The body part preferably includes a plurality of second
protrusion parts or a plurality of second recessed parts.
[0024] A pulling-up-type continuous casting method according to an
aspect of the present invention includes: a step of submerging a
drawing member into a molten-metal surface of molten metal held in
a holding furnace; and a step of thawing the molten metal by the
drawing member and making the drawn 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, in which the drawing member is formed from a body part and a
tip part, the tip part including a tip having a horizontal cross
section smaller than that of the body part. As a result, it is
possible to easily submerge the starter (drawing member) into the
molten metal by making the starter (drawing member) break through
an oxide film formed on the molten-metal surface of the molten
metal, thus improving the molten-metal drawing property of the
starter.
[0025] The tip part preferably has a tapered shape such that the
tip part becomes narrower toward its tip.
[0026] The angle of the tip is preferably 45 degrees or
smaller.
[0027] The tip part preferably includes a plurality of tips.
[0028] The drawing member preferably further includes at least one
of a first protrusion part protruding from a side of the tip part
or the body part and a first recessed part recessed from the side
of the tip part or the body part.
[0029] The protrusion length of the first protrusion part or the
recess depth of the first recessed part is preferably 1 mm or
larger.
[0030] The drawing member preferably includes a plurality of first
protrusion parts or a plurality of first recessed parts.
[0031] The tip part preferably further includes an opening opened
from the tip, and at least one of a second protrusion part
protruding from a side of the opening and a second recessed part
recessed from the side of the opening.
[0032] The protrusion length of the second protrusion part or the
recess depth of the second recessed part is preferably 1 mm or
larger.
[0033] The tip part preferably includes a plurality of second
protrusion parts or a plurality of second recessed parts.
[0034] A pulling-up-type continuous casting method according to
another aspect of the present invention includes: a step of
submerging a drawing member into a molten-metal surface of molten
metal held in a holding furnace; and a step of drawing the molten
metal by the drawing member and making the drawn 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, in which the drawing member is formed from a
body part, and at least one of a first protrusion part protruding
from a side of the body part and a first recessed part recessed
from the side of the body part. As a result, it is possible to
improve the bonding force between the starter (drawing member) and
the molten metal, thus improving the molten-metal drawing property
of the starter.
[0035] The protrusion length of the first protrusion part or the
recess depth of the first recessed part is preferably 1 mm or
larger.
[0036] The drawing member preferably includes a plurality of first
protrusion parts or a plurality of first recessed parts.
[0037] The body part preferably further includes an opening opened
from the tip, and at least one of a second protrusion part
protruding from a side of the opening and a second recessed part
recessed from the side of the opening.
[0038] The protrusion length of the second protrusion part or the
recess depth of the second recessed part is preferably 1 mm or
larger.
[0039] The body part preferably includes a plurality of second
protrusion parts or a plurality of second recessed parts.
Advantageous Effects of Invention
[0040] The present invention can improve the molten-metal drawing
property of the starter.
BRIEF DESCRIPTION OF DRAWINGS
[0041] FIG. 1 is a cross section showing a configuration example of
a free casting apparatus according to a first exemplary
embodiment;
[0042] FIG. 2 is a plane view of a shape defining member 102
provided in the free casting apparatus shown in FIG. 1;
[0043] FIG. 3 is a perspective view showing a configuration example
of a starter ST provided in a free casting apparatus according to
the first exemplary embodiment;
[0044] FIG. 4 shows a molten-metal drawing method for a free
casting apparatus according to the first exemplary embodiment;
[0045] FIG. 5 is a perspective view showing another configuration
example of the starter ST;
[0046] FIG. 6 is a perspective view showing another configuration
example of the starter ST;
[0047] FIG. 7 is a cross section showing a configuration example of
a free casting apparatus according to a second exemplary
embodiment;
[0048] FIG. 8 is a perspective view showing a configuration example
of a starter ST provided in a free casting apparatus according to
the second exemplary embodiment;
[0049] FIG. 9 shows a molten-metal drawing method for a free
casting apparatus according to the second exemplary embodiment;
[0050] FIG. 10 is a perspective view showing another configuration
example of the starter ST;
[0051] FIG. 11 is a perspective view showing another configuration
example of the starter ST;
[0052] FIG. 12 is a perspective view showing another configuration
example of the starter ST;
[0053] FIG. 13 is a perspective view showing another configuration
example of the starter ST;
[0054] FIG. 14 is a perspective view showing another configuration
example of the starter ST;
[0055] FIG. 15 is a perspective view showing another configuration
example of the starter ST;
[0056] FIG. 16 is a perspective view showing another configuration
example of the starter ST;
[0057] FIG. 17 is a graph showing results of drawing success rate
experiments according to the tip angle of the starter ST shown in
FIG. 16;
[0058] FIG. 18 shows photograms showing results of the drawing
success rate experiments according to the tip angle of the starter
ST shown in FIG. 16;
[0059] FIG. 19 is a graph showing results of drawing success rate
experiments according to the protrusion length of the protrusion
part of the starter ST shown in FIG. 16;
[0060] FIG. 20 shows photographs showing results of a drawing
success rate experiments according to the protrusion length of the
protrusion part of the starter ST shown in FIG. 16;
[0061] FIG. 21 is a cross section showing another configuration
example of a free casting apparatus according to the present
invention; and.
[0062] FIG. 22 is a plane view of a shape defining member 102
provided in the free casting apparatus shown in FIG. 17.
DESCRIPTION OF EMBODIMENTS
[0063] 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
[0064] 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 cross
section showing a configuration example 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 (holding
furnace) 101, an outer-shape defining member 102a, a support rod
103, an actuator 104, a cooling nozzle 105, and a drawing section
106.
[0065] The molten-metal holding furnace 101 contains, for example,
molten metal M1 such as aluminum or its alloy, and maintains the
molten metal M1 at a predetermined temperature. This exemplary
embodiment is explained by using an example where the molten metal
M1 is aluminum. Note that needless to say, the molten metal M1 may
be a metal other than aluminum or an alloy thereof. 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.
[0066] The outer-shape defining member 102a is made of ceramic or
stainless, for example, and disposed in the vicinity of the
molten-metal surface. In the example shown in FIG. 1, the
outer-shape defining member 102a is disposed so that the
outer-shape defining member 102a is in contact with the
molten-metal surface. However, the outer-shape defining member 102a
may be disposed so that its bottom main surface (molten-metal
surface side) is not in contact with the molten-metal surface.
Specifically, the outer-shape defining member 102a may be disposed
so that a predetermined gap (e.g., about 0.5 mm) is formed between
the bottom main surface and the molten-metal surface.
[0067] The outer-shape defining member 102a defines the outer shape
of a cast metal M3 to be cast. The cast metal M3 shown in FIG. 1 is
a rectangular-column cast-metal article having a rectangular shape
in a horizontal cross section (hereinafter referred to as "lateral
cross section"). That is, more specifically, the outer-shape
defining member 102a defines the outer diameter on the lateral
cross section of the cast metal M3.
[0068] FIG. 2 is a plane view of the outer-shape defining member
102a. Note that the cross section of the outer-shape defining
member 102a shown in FIG. 1 corresponds to a cross section taken
along the line I-I in FIG. 2. As shown in FIG. 2, the outer-shape
defining member 102a has, for example, a rectangular shape in the
plan view, and has a rectangular opening at the center. This
opening serves as a molten-metal passage section 102b through which
molten metal passes. In this manner, the outer-shape defining
member 102a and the molten-metal passage section 102b constitute a
shape defining member 102.
[0069] The drawing section 106 includes a starter (drawing member)
ST that is submerged into the molten metal M1, and a pulling-up
machine PL that drives the starter ST, for example, in the vertical
direction.
[0070] As shown in FIG. 1, after the molten metal M1 adheres to the
submerged starter ST, the molten metal M1 follows the starter ST
and is pulled up by the starter ST while maintaining its outer
shape by its surface film and/or the surface tension. Then, the
molten metal M1 passes through the molten-metal passage section
102b. Note that the molten metal that follows the starter ST (or
the cast metal M3 that is formed as the molten metal M1 drawn by
the starter ST solidifies) and is pulled up from the molten-metal
surface by the surface film of the molten metal M1 and/or the
surface tension is called "held molten metal M2". Further, the
interface between the cast metal M3 and the held molten metal M2 is
the solidification interface.
[0071] The starter ST is formed of, for example, material having a
high melting point equal to or higher than the melting point of the
molten metal M1. By doing so, the erosion of the starter can be
prevented to some extent. This exemplary embodiment is explained by
using an example where the starter ST is made of aluminum, i.e.,
the same material as the molten metal M1. Note that the material
for the starter ST is not limited to aluminum. That is, the starter
ST may be formed of stainless, iron, an alloy thereof, ceramic, or
the like.
[0072] FIG. 3 is a perspective view showing a configuration example
of the starter ST according to the first exemplary embodiment. The
starter ST shown in FIG. 3 is composed of a body part 107 and a tip
part 108. Note that the body part 107 and the tip part 108 are
integrally formed. In the example shown in FIG. 3, the body part
107 has a rectangular-column shape. Further, the tip part 108
includes a tip 109 that is the first to come into contact with the
molten metal M1 when the starter ST is lowered, and the other end
(i.e., the other tip) connected to the body part 107. Note that the
horizontal cross section (lateral cross section) of the tip 109 of
the tip part 108 is smaller than that of the body part 107. In the
example shown in FIG. 3, the tip part 108 has a tapered shape
(pointed shape) such that the tip part 108 becomes narrower toward
the tip 109. As a result, since the starter ST can be easily
submerged into the molten metal M1 by making the starter ST break
through an oxide film formed on the molten-metal surface of the
molten metal M1, the molten metal M1 drawing property of the
starter ST can be improved.
[0073] The support rod 103 supports the outer-shape defining member
102a. Note that the support rod 103 is connected to the actuator
104.
[0074] The actuator 104 has a function of moving the outer-shape
defining member 102a in the up/down direction (vertical direction)
and in the horizontal direction through the support rod 103. In
this manner, it is possible to move the outer-shape defining member
102a downward as the molten-metal surface is lowered due to the
advance of the casting process. Further, since the outer-shape
defining member 102a can be moved in the horizontal direction, the
shape in the longitudinal direction of the cast metal M3 can be
arbitrarily changed.
[0075] The cooling nozzle (cooling unit) 105 sprays a cooling gas
(such as air, nitrogen, and argon) on the starter ST and/or the
cast metal M3, and thereby cools the starter ST and/or the cast
metal M3. By cooling the starter ST and/or the cast metal M3 by the
cooling gas while pulling up the cast metal M3 by using the
pulling-up machine PL connected to the starter ST, the held molten
metal M2 located in the vicinity of the solidification interface is
successively solidified and the cast metal M3 is continuously
formed.
[0076] Next, a free casting method according to this exemplary
embodiment is explained with reference to FIGS. 1 to 4. FIG. 4
shows a molten-metal drawing method for a free casting apparatus
according to the first exemplary embodiment.
[0077] Firstly, molten metal M1 is set (i.e., contained) in the
molten-metal holding furnace 101 (S101 in FIG. 4).
[0078] Next, the pointed starter ST is lowered, and the tip part
108 of the starter ST is made to pass through the molten-metal
passage section 102b and brought into contact with the molten-metal
surface of the molten metal M1 (S 102 in FIG. 4). After that, the
starter ST is further lowered and submerged into the molten metal
M1 by making the tip part 108 break through an oxide film formed on
the molten-metal surface of the molten metal M1 (S 103 in FIG.
4).
[0079] Next, the starter ST starts to be pulled up at a
predetermined speed (S104 in FIG. 4). 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 (drawn) from the
molten-metal surface by the surface film and/or the surface
tension. The pulled-up molten metal M1 forms held molten metal M2.
As shown in FIG. 1, the held molten metal M2 is formed in the
molten-metal passage section 102b. In other words, the held molten
metal M2 is shaped into a given shape by the outer-shape defining
member 102a.
[0080] Next, the starter ST and the cast metal M3 are cooled by a
cooling gas sprayed from the cooling nozzle 105. As a result, the
held molten metal M2 is successively solidified from its upper side
toward its lower side, and hence the cast metal M3 grows. In this
manner, the cast metal M3 can be continuously cast.
[0081] As described above, in the free casting apparatus according
to this exemplary embodiment, the starter ST includes the (pointed)
tip part including the tip having a horizontal cross section
smaller than that of the body part. As a result, the free casting
apparatus according to this exemplary embodiment can easily
submerge the starter ST into the molten metal M1 by making the
starter ST break through the oxide film formed on the molten-metal
surface of the molten metal M1, thus making it possible to improve
the molten metal M1 drawing property of the starter ST. When the
starter ST is submerged into the molten metal M1, if the oxide film
on the molten-metal surface adheres to the wall surface of the tip
of the starter ST and the starter ST is pulled up with the oxide
film attached to its wall surface, the adhesion of the molten metal
to the wall surface of the starter ST is likely to deteriorate when
the molten metal is drawn at the initial stage of the pull-up
process. When the starter ST is submerged, if the tip of the
starter ST enters into the non-oxidized molten metal by breaking
through the oxide film, the oxide film is less likely to adhere to
the wall surface of the tip of the starter ST and the non-oxidized
molten metal adheres to the tip of the starter ST. When the
non-oxidized molten metal adheres to the tip of the starter ST, the
molten metal is more likely to be drawn in a relatively stable
manner in the subsequent pulling-up process. Therefore, tearing in
a part of the molten metal, which would otherwise occur halfway
through the pulling-up process, is less likely to occur.
Other Configuration Examples of Starter ST According to First
Exemplary Embodiment
[0082] Other configuration examples of the starter ST are explained
hereinafter with reference to FIGS. 5 and 6. FIGS. 5 and 6 are
perspective views showing other configuration examples of the
starter ST.
[0083] In a starter ST shown in FIG. 5, the tip part 108 has a
rectangular-column shape whose horizontal cross section (lateral
cross section) is smaller than that of the body part 107. In a
starter ST shown in FIG. 6, the tip part 108 includes a plurality
of tips 109. The use of the starter ST shown in FIG. 5 or 6 makes
it possible to achieve an advantageous effect equivalent to that
which is achieved when the starter ST shown in FIG. 3 is used. Note
that the tip part 108 of the starter ST can be changed as
appropriate to other structures whose horizontal cross sections
(lateral cross sections) are smaller than that of the body part
107.
Second Exemplary Embodiment
[0084] FIG. 7 is a cross section showing a configuration example of
a free casting apparatus according to a second exemplary
embodiment. The free casting apparatus shown in FIG. 7 is different
from the free casting apparatus shown in FIG. 1 in regard to the
shape of the starter ST. The rest of the configuration of the free
casting apparatus shown in FIG. 7 is similar to that of the free
casting apparatus shown in FIG. 1, and therefore its explanation is
omitted.
[0085] FIG. 8 is a perspective view showing a configuration example
of the starter ST according to the second exemplary embodiment. The
starter ST shown in FIG. 8 is composed of a body part (a body part
having a rectangular-column shape in this example) 107 and
protrusion parts (first protrusion parts) 110. Note that the body
part 107 and the protrusion parts 110 are integrally formed. Note
that the protrusion parts 110 are provided such that they protrude
from sides of the body part 107. As a result, when the starter ST
is pulled up, the molten metal M1 is raised by the protrusion parts
110. More specifically, when the starter ST is pulled up, a surface
solidification layer formed near the molten-metal surface of the
molten metal M1 is raised by the protrusion parts 110. That is, the
bonding force between the starter ST and the molten metal M1 is
improved. As a result, it is possible to prevent the drawn molten
metal M1 from being torn apart due to the gravitational pull of the
surface solidification layer. That is, the molten metal M1 drawing
property of the starter ST can be improved.
[0086] Next, a free casting method according to this exemplary
embodiment is explained with reference to FIGS. 7 to 9. FIG. 9
shows a method for drawing molten metal in a free casting apparatus
according to the second exemplary embodiment.
[0087] Firstly, molten metal M1 is set (i.e., contained) in the
molten-metal holding furnace 101 (S201 in FIG. 9).
[0088] Next, the starter ST including the protrusion parts 110 is
lowered, and then the starter ST is made to pass through the
molten-metal passage section 102b and brought into contact with the
molten-metal surface of the molten metal M1 (S202 in FIG. 9). After
that, the starter ST is further lowered and the starter ST is
submerged into the molten metal M1 (S203 in FIG. 9).
[0089] Next, the starter ST starts to be pulled up at a
predetermined speed (S104 in FIG. 4). 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 (drawn) from the
molten-metal surface by the surface film and/or the surface
tension. The pulled-up molten metal M1 forms held molten metal M2.
Note that since the surface solidification layer formed near the
molten-metal surface of the molten metal M1 is raised by the
protrusion parts 110, the molten metal M1 forms the held molten
metal M2 without being torn apart due to the gravitational pull of
the surface solidification layer. As shown in FIG. 7, the held
molten metal M2 is formed in the molten-metal passage section 102b.
In other words, the held molten metal M2 is shaped into a given
shape by the outer-shape defining member 102a.
[0090] Next, the starter ST and the cast metal M3 are cooled by a
cooling gas sprayed from the cooling nozzle 105. As a result, the
held molten metal M2 is successively solidified from its upper side
toward its lower side, and hence the cast metal M3 grows. In this
manner, the cast metal M3 can be continuously cast.
[0091] As described above, in the free casting apparatus according
to this exemplary embodiment, the starter ST includes the
protrusion parts protruding from the sides of the body part 107. As
a result, the free casting apparatus according to this exemplary
embodiment can improve the bonding force between the starter ST and
the molten metal M1, thus making it possible to improve the molten
metal M1 drawing property of the starter ST. The fact that the
contact area between the starter ST and the molten metal is
increased by the steps of the protrusion parts of the starter ST
and the molten metal is more likely to get snagged on the
protrusion parts of the starter ST is considered to be one of the
reasons for the improvement in the bonding force.
Other Configuration Examples of Starter ST According to Second
Exemplary Embodiment
[0092] Other configuration examples of the starter ST are explained
hereinafter with reference to FIGS. 10 and 16. FIGS. 10 and 16 are
perspective views showing other configuration examples of the
starter ST.
[0093] A starter ST shown in FIG. 10 includes a plurality of
protrusion parts 110 protruding from the sides of the body part
107. A starter ST shown in FIG. 11 includes protrusion parts 110
that protrude toward the pulling-up direction from the sides of the
body part 107. The use of the starter ST shown in FIG. 10 or 11
makes it possible to improve the bonding force between the starter
ST and the molten metal M1 even further.
[0094] A starter ST shown in FIG. 12 includes, instead of the
protrusion parts 110, recessed parts (first recessed parts) 111
recessed from the sides of the body part 107. A starter ST shown in
FIG. 13 includes a plurality of recessed parts 111 recessed from
the sides of the body part 107. The use of the starter ST shown in
FIG. 12 or 13 makes it possible to improve the bonding force
between the starter ST and the molten metal M1 as in the case of
using the starter ST shown in FIG. 8 or 10 or the like.
[0095] A starter ST shown in FIG. 14 further includes an opening
112 opened from the center of the tip of the body part 107 and
protrusion parts (second protrusion parts) 113 protruding from the
side of the opening 112. Note that recessed parts (second recessed
parts) recessed from the sides of the opening 112 may be provided
instead of the protrusion parts 113. The use of the starter ST
shown in FIG. 14 makes it possible to improve the bonding force
between the starter ST and the molten metal M1 as in the case of
the above-shown other starters ST.
[0096] It should be noted that the shapes of the starters ST
explained in the first exemplary embodiment may be combined with
the shapes of the starters ST explained in the second exemplary
embodiment. In such cases, for example, the protrusion parts 110
may protrude from the sides of the tip part 108 as well as from the
sides of the body part 107. Further, the recessed parts 111 may be
recessed from the sides of the tip part 108 as well as from the
sides of the body part 107. Further, the opening 112 is opened from
the tip of the tip part 108. As a result, the starter ST can be
easily submerged into the molten metal M1 by making the starter ST
break through the oxide film formed on the molten-metal surface of
the molten metal M1 and the bonding force between the starter ST
and the molten metal M1 can be improved.
[0097] Starters ST shown in FIGS. 15 and 16 are examples in which
the shapes of starters ST explained in the first and second
exemplary embodiments arc combined with each other. The starter ST
shown in FIG. 15 includes protrusion parts 110 protruding from the
sides of the body part 107 in addition to the shape of the starter
ST shown in FIG. 3. As a result, the starter ST shown in FIG. 15
has an arrow-like shape in the front view. The starter ST shown in
FIG. 16 resembles the starter ST shown in FIG. 15 and can be easily
formed by hollowing out parts of the sides in the long-side
direction of a plate material having a rectangular shape in the
front view and cutting off two corners adjoining to the side in the
short-side direction thereof.
(Experiment Results)
[0098] Next, the inventors have conducted experiments for examining
the molten metal M1 drawing property of the starter ST while
variously changing the tip angle A of the starter ST and the
protrusion length L of its protrusion parts 110. The results of the
experiments are explained hereinafter.
[0099] Note that the starter ST shown in FIG. 16 was used in the
experiments. The starter ST is made of an aluminum alloy (A5052)
and kept at a normal temperature before it is submerged into the
molten metal M1. Further, the molten metal M1 is also made of the
aluminum alloy (A5052) and kept at 720.degree. C. The pulling-up
speed of the starter ST is 1 mm/sec.
[0100] FIG. 17 is a graph showing results of drawing success rate
experiments according to the tip angle of the starter ST. Note that
the term "drawing success rate" means the rate at which the starter
ST was able to be submerged into the molten metal M1 by breaking
through the oxide film formed on the molten-metal surface of the
molten metal M1 (the success rate with respect to the total number
of experiments).
[0101] As shown in FIG. 17, it can be seen that the smaller the tip
angle A is, the higher the drawing success rate becomes. In
particular, when the tip angle A is 45.degree. or smaller, the
drawing success rate is increased to nearly 100%.
[0102] FIG. 18 shows photo grams showing results of the drawing
success rate experiments according to the tip angle A of the
starter ST. The left photogram shows an example where the tip angle
A was large and the molten metal M1 was not able to be successfully
drawn. In this example, since the starter was not able to
completely break through the oxide film formed on the molten-metal
surface of the molten metal M1, the remaining oxide film adhered to
the surface of the held molten metal M2 and affected the shape of
the molded article. The right photogram shows an example where the
tip angle A was small and the molten metal M1 was successfully
drawn. In this example, since the starter was able to completely
break through the oxide film formed on the molten-metal surface of
the molten metal M1, the oxide film had no effect on the shape of
the molded article.
[0103] FIG. 19 is a graph showing results of drawing success rate
experiments according to the protrusion length L of the protrusion
parts 110 of the starter ST. Note that the term "drawing success
rate" means the rate at which the surface solidification layer
formed near the molten-metal surface of the molten metal M1 was
raised by the protrusion parts 110 and hence the molten metal M1
was able to be drawn with accuracy (the success rate with respect
to the total number of experiments).
[0104] As shown in FIG. 19, it can be seen that the larger the
protrusion length L is, the higher the drawing success rate
becomes. In particular, when the protrusion length L is 1.0 mm or
longer, the drawing success rate is increased to nearly 100%.
[0105] FIG. 20 shows photograms showing results of the drawing
success rate experiments according to the protrusion length L of
the protrusion parts 110 of the starter ST. The left photogram
shows an example where the protrusion length L was short and the
molten metal M1 was not able to be successfully drawn. In this
example, the protrusion parts 110 cannot sufficiently support the
gravitational pull (i.e., the weight) of the surface solidification
layer and the drawn molten metal M1 is almost torn apart by the
gravitational pull of the surface solidification layer. The right
photogram shows an example where the protrusion length L was long
and it was possible for the molten metal M1 to be successfully
drawn. In this example, the protrusion parts 110 can support the
gravitational pull (i.e., the weight) of the surface solidification
layer and the molten metal M1 is drawn without causing the molten
metal M1 to be torn apart due to the gravitational pull of the
surface solidification layer.
[0106] As has been described above, in the free casting apparatuses
according to the above-described first and second exemplary
embodiments, the starter ST includes the tip part 108 including the
tip 109 having a cross section smaller than that of the body part
107 or/and includes protrusion parts 111 protruding from the sides
of the body part 107 or the like. As a result, in the free casting
apparatuses according to the above-described first and second
exemplary embodiments, the starter ST can be easily submerged into
the molten metal M1 by making the starter ST break through the
oxide film formed on the molten-metal surface of the molten metal
M1 or/and the bonding force between the starter ST and the molten
metal M1 can be improved. Therefore, the molten metal M1 drawing
property of the starter ST can be improved.
[0107] Although example cases where a cast-metal article having a
rectangular-column shape re angular-column cast-metal article) is
cast are explained in the above-described first to fourth exemplary
embodiments, the present invention is not limited to such examples.
The present invention can also be applied to cases where a
cast-metal article having a rectangular-tubular shape, a
cylindrical shape, a circular-tubular shape, or other shapes is
cast. A case where a cast-metal article having a tubular shape is
cast is briefly explained hereinafter with reference to FIGS. 21
and 22.
[0108] FIG. 21 is a cross section showing another specific
configuration example of a free casting apparatus according
according to the present invention. The free casting apparatus
shown in FIG. 21 includes an inner-shape defining member 102c in
addition to the outer-shape defining member 102a.
[0109] The inner-shape defining member 102c defines the inner shape
of a cast metal M3 to be cast and the outer-shape defining member
102a defines the outer shape of the cast metal M3 to be cast. The
cast metal M3 shown in FIG. 21 is a hollow cast-metal article
having a ring shape in a horizontal cross section (hereinafter
referred to as "lateral cross section") (that is, the cast metal M3
shown in FIG. 9 is a pipe). That is, more specifically, the
inner-shape defining member 102c defines the inner diameter on the
lateral cross section of the cast metal M3 and the outer-shape
defining member 102a defines the outer diameter on the lateral
cross section of the cast metal M3.
[0110] FIG. 22 is a plane view of the inner-shape defining member
102c and the outer-shape defining member 102a. Note that the cross
section of the inner-shape defining member 102c and the outer-shape
defining member 102a in FIG. 11 corresponds to a cross section
taken along the line II-II in FIG. 22. As shown in FIG. 22, the
outer-shape defining member 102a has, for example, a rectangular
shape in the plan view, and has a rectangular opening at the
center. The inner-shape defining member 102c has a rectangular
shape in the plan view and is disposed at the center of the opening
of the outer-shape defining member 102a. The gap between the
inner-shape defining member 102c and the outer-shape defining
member 102a serves as the molten-metal passage section 102b through
which the molten metal passes. In this manner, the inner-shape
defining member 102c, the outer-shape defining member 102a, and the
molten-metal passage section 102b constitute a shape defining
member 102. With this configuration, a cast-metal article having a
rectangular-tubular shape is cast.
[0111] Note that the present invention is not limited to the
above-described first to fourth exemplary embodiments, and various
modifications can be made without departing the spirit and scope of
the present invention. For example, the above-described
configuration examples may be combined and used at the same
time.
[0112] This application is based upon and claims the benefit of
priority from Japanese patent application No. 2013-158205, filed on
Jul. 30, 2013, the disclosure of which is incorporated herein in
its entirety by reference.
REFERENCE SIGNS LIST
[0113] 101 MOLTEN METAL HOLDING VESSEL [0114] 102 SHAPE DEFINING
MEMBER [0115] 102a OUTER-SHAPE DEFINING MEMBER [0116] 102b
MOLTEN-METAL PASSAGE SECTION [0117] 102c INNER-SHAPE DEFINING
MEMBER [0118] 103 SUPPORT ROD [0119] 104 ACTUATOR [0120] 105
COOLING NOZZLE [0121] 106 DRAWING SECTION [0122] 107 BODY PART
[0123] 108 TIP PART [0124] 109 TIP [0125] 110 PROTRUSION PART
[0126] 111 RECESSED PART [0127] 112 OPENING [0128] M1 MOLTEN METAL
[0129] M2 HELD MOLTEN METAL [0130] M3 CAST METAL [0131] ST STARTER
[0132] PL PULLING-UP MACHINE
* * * * *