U.S. patent application number 14/002954 was filed with the patent office on 2013-12-26 for die cast casting apparatus and method for releasing casting from mold.
This patent application is currently assigned to TOYOTA JIDOSHA KABUSHIKI KAISHA. The applicant listed for this patent is Hiroyuki Ikuta, Naoaki Sugiura. Invention is credited to Hiroyuki Ikuta, Naoaki Sugiura.
Application Number | 20130340968 14/002954 |
Document ID | / |
Family ID | 46797611 |
Filed Date | 2013-12-26 |
United States Patent
Application |
20130340968 |
Kind Code |
A1 |
Sugiura; Naoaki ; et
al. |
December 26, 2013 |
DIE CAST CASTING APPARATUS AND METHOD FOR RELEASING CASTING FROM
MOLD
Abstract
A die casting apparatus includes: a fixed mold and a movable
mold for forming a casting, wherein an insert core is disposed
slidably in a movable main mold of the movable mold to form a
protruding portion of the casting. The movable mold includes: a
casting ejecting part for releasing the casting from the main mold,
a core moving part for moving the core in a casting demolding
direction, and a protruding-portion demolding part for releasing
the protruding portion from the core. In a first demolding step, a
control part controls the casting ejecting part, core moving part,
and protruding-portion demolding part to release the casting from
the main mold by the casting ejecting part and move the core
together with the casting by the core moving part. In a second
demolding step, the protruding portion is released from the core by
the protruding-portion demolding part.
Inventors: |
Sugiura; Naoaki; (Anjo-shi,
JP) ; Ikuta; Hiroyuki; (Nisshin-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Sugiura; Naoaki
Ikuta; Hiroyuki |
Anjo-shi
Nisshin-shi |
|
JP
JP |
|
|
Assignee: |
TOYOTA JIDOSHA KABUSHIKI
KAISHA
Toyota-shi
JP
|
Family ID: |
46797611 |
Appl. No.: |
14/002954 |
Filed: |
March 4, 2011 |
PCT Filed: |
March 4, 2011 |
PCT NO: |
PCT/JP2011/055125 |
371 Date: |
September 3, 2013 |
Current U.S.
Class: |
164/131 ;
164/302 |
Current CPC
Class: |
B22D 17/24 20130101;
B22D 17/32 20130101; B22D 17/2236 20130101 |
Class at
Publication: |
164/131 ;
164/302 |
International
Class: |
B22D 17/22 20060101
B22D017/22 |
Claims
1. A die casting apparatus including a fixed die and a movable die
to form a cavity for molding a casting, in which an insert core is
slidably provided in a movable main die of the movable die to form
a protruding portion of the casting, wherein the movable die
includes: product ejecting means to release the casting from the
movable main die; core moving means to move the core in a demolding
direction of the casting; and protruding-portion demolding means
placed on both sides of the insert core formed of a plurality of
straight extending standing plates arranged side by side, the both
sides being located in a straight extending direction of the
straight extending standing plates, to release the protruding
portion from the core, wherein control means to control operations
of the product ejecting means, the core moving means, and the
protruding-portion demolding means is configured to execute a first
demolding step in which the product ejecting means releases the
casting from the movable main die and the core moving means moves
the core in association with the casting, and a second demolding
step in which the protruding-portion demolding means alternately
pushes each of the both sides in the straight extending direction
of the standing plates forming the insert core to release the
protruding portion from the core.
2. The die casting apparatus according to claim 1, wherein the
protruding-portion demolding means is configured to perform the
second demolding step by pushing the casting near the protruding
portion in the demolding direction.
3. (canceled)
4. The die casting apparatus according to claim 1, wherein the core
moving means and the protruding-portion demolding means are
integrally formed by a hydraulic unit configured to separately
independently extend and contract operation rods connected to the
core and ejector pins to be pressed against a portion of the
casting near the protruding portion.
5. The die casting apparatus according to claim 1, wherein the core
moving means and the protruding-portion demolding means are
integrally formed by a hydraulic unit configured to separately
independently extend and contract operation rods connected to the
core and plate-shaped ejector blocks to be pressed against the
casting near the protruding portion.
6. The die casting apparatus according to claim 4, wherein the
product ejecting means includes a plurality of ejector pins or
ejector blocks fixed to an ejector plate to be moved by a hydraulic
cylinder, and the control means is hydraulic control means to drive
and control the hydraulic unit and the hydraulic cylinder.
7. A die casting apparatus including a fixed die and a movable die
to form a cavity for molding a casting, in which an insert core is
slidably provided in a movable main die of the movable die to form
a protruding portion of the casting, the movable die includes:
product ejecting means to release the casting from the movable main
die; core moving means to move the core formed of a plurality of
separate blocks so that each of the separate blocks of the core is
moved in the demolding direction of the casting to release the
protruding portion from the insert die; and protruding-portion
demolding means to push the casting at a portion near the
protruding portion in the demolding direction, and wherein control
means to control operations of the product ejecting means, the core
moving means, and the protruding-portion demolding means is
configured to execute a first demolding step in which the product
ejecting means releases the casting from the movable main die and
the core moving means moves the core in association with the
casting, and a second demolding step in which the separate blocks
are stepwise moved relatively in an opposite direction to the
demolding direction by the core moving means with respect to the
protruding portion of the casting pushed or supported by the
protruding-portion demolding means to release the protruding
portion from the core.
8. The die casting apparatus according to claim 7, wherein when the
core is configured to form the protruding portion consisting of a
plurality of straight extending standing plates arranged side by
side, the separate blocks are separated in a straight extending
direction of the standing plates.
9. The die casting apparatus according to claim 7, wherein the core
moving means and the protruding-portion demolding means are
integrally formed by a hydraulic unit configured to separately
independently extend and contract operation rods connected to the
separate blocks of the core and ejector pins to be pressed against
the casing near the protruding portion.
10. The die casting apparatus according to claim 7, wherein the
core moving means and the protruding-portion demolding means are
integrally formed by a hydraulic unit configured to separately
independently extend and contract operation rods connected to the
separate blocks of the core and plate-shaped ejector blocks to be
pressed against the casing near the protruding portion.
11. The die casting apparatus according to claim 9, wherein the
product ejecting means includes a plurality of ejector pins or
ejector blocks fixed to an ejector plate to be moved by a hydraulic
cylinder, and the control means is hydraulic control means to drive
and control the hydraulic unit and the hydraulic cylinder.
12. (canceled)
13. (canceled)
14. (canceled)
15. A method for releasing a casting from a die, using a die
casting apparatus to form the casting including a protruding
portion, the method including separating a movable die from a fixed
die for die opening and then demolding the casting from the movable
die, wherein the method includes: a first demolding step including
moving an insert core configured to form the protruding portion in
association with the casting to release a portion of the casting
other than the protruding portion from a movable main die of the
movable die; and a second demolding step including releasing the
protruding portion from the core, wherein when the core is
configured to form the protruding portion consisting of a plurality
of straight extending standing plates arranged side by side, the
second demolding step uses protruding-portion demolding means
placed on both sides of the core corresponding to both side
positions of the standing plates in a straight extending direction
and includes alternately operating each side of the
protruding-portion demolding means to push the casting in the
demolding direction.
16. A method for releasing a casting from a die, using a die
casting apparatus to form the casting including a protruding
portion, the method including separating a movable die from a fixed
die for die opening and then demolding the casting from the movable
die, wherein the method includes: a first demolding step including
moving an insert core configured to form the protruding portion in
association with the casting to release a portion of the casting
other than the protruding portion from a movable main die of the
movable die; and a second demolding step including releasing the
protruding portion from the core, wherein the second demolding step
uses the core formed of a plurality of separate blocks and includes
stepwise moving the separate blocks to release the protruding
portion by each separate block.
17. (canceled)
18. (canceled)
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This is a national phase application based on the PCT
International Patent Application No. PCT/JP2011/055125 filed on
Mar. 4, 2011, the entire contents of which are incorporated herein
by reference.
TECHNICAL FIELD
[0002] The present invention relates to a die casting apparatus and
a method for releasing a casting from a die or mold to produce a
casting including a plurality of protruding portions such as a
cooling fin.
BACKGROUND ART
[0003] A die casting apparatus includes a fixed or stationary die
and a movable die arranged so that a cavity is defined by the
movable die and the fixed die in a closed state. The fixed die and
the movable die are each provided with ejector pins for releasing a
casting from the dies after casting. In casting, so-called vacuum
casting is performed in which a predetermine amount of molten metal
is supplied to the cavity under vacuum, the molten metal being
injected under high pressure. After the molten metal in the cavity
is solidified and a casting is formed, die-opening by retreating
the movable die and die-releasing, or demolding, by ejecting the
casting out of the movable die by use of ejector pins and the like
are performed. FIG. 11 is a cross sectional view of a die casting
apparatus showing conceptually a state of such a demolding
operation.
[0004] A casting shown herein is a cooling fin illustrated in FIG.
12. A casting 80 integrally includes a plurality of fin portions 81
formed of standing thin plates arranged in parallel and a flat
plate portion 82 vertical to the fin portions 81. FIG. 11 shows how
to produce this casting 80, which is seen in a side direction (X
direction) in which the fin portions 81 are arranged side by side.
A die casting apparatus 100 is configured so that a movable die 102
is separated from a fixed die 101 and then a hydraulic cylinder 103
is actuated to extend ejector pins 105 to forcibly release the
casting 80 from the movable die 102.
RELATED ART DOCUMENTS
Patent Documents
[0005] Patent Document 1: JP8(1996)-A-300132
SUMMARY OF INVENTION
Problems to be Solved by the Invention
[0006] The casting 80 including a protruding portion such as the
fin portions 81 has a large contact area with the dies and thus
exhibits large resistance when the casting 80 is being released
from the dies after casting. In the conventional die casting
apparatus 100, therefore, some problems may be caused, for example,
the ejector pins 105 are broken or bent. In this respect, Patent
Document 1 discloses a die casting apparatus in which an insert
core is set in a movable die for forming a fin. This apparatus
includes a fluid supply means for supplying a liquid such as water
and machine oil under high pressure. Accordingly, the core is moved
back after solidification of molten metal, thereby generating a
clearance with respect to a cooling fin which is a product. The
liquid is then supplied thereto to apply pressure. This reduces an
ejection load of the ejector pins performed at the same time.
However, the die casting apparatus in Patent Document 1 has to
include the fluid supply means and others, resulting in a
complicated structure, and needing time to deal with the
liquid.
[0007] On the other hand, in the case of the die casting apparatus
100, when the ejector pins 105 push an area near the fin portions
81, stress is apt to concentrate on a corner 85 at a boundary
between the fin portions 81 and the flat plate portion 82, causing
breakage of that boundary portion. In this case, the casting 80 is
a defective product, leading to a decreased yield, and also the fin
portions 81 could not be released from the die and thus are broken
and left in the mold. To prevent breakage of the casting 80, it is
therefore conceivable to directly push the fin portions 81 for
demolding. However, the apparatus provided with a plurality of pins
for pushing the thin fin portions 81 results in a complicated
structure and an increased cost. If a tip portion of each fin
pushed by the ejector pin is buckled and deformed, such a deformed
fin deteriorates the capacity of the cooling fin constituting a
heat exchanger. Thus, the fin tip portions have to be subjected to
finish machining to maintain the cooling capacity. This requires
troubles and causes loss in manufacturing time.
[0008] The present invention has been made to solve the above
problems and has a purpose to provide a die casting apparatus and a
method for releasing a casting from a die to enable easy demolding
of the casting.
Means of Solving the Problems
[0009] To achieve the above purpose, one aspect of the invention
provides a die casting apparatus including a fixed die and a
movable die to form a cavity for molding a casting, in which an
insert core is slidably provided in a movable main die of the
movable die to form a protruding portion of the casting, wherein
the movable die includes: product ejecting means to release the
casting from the movable main die; core moving means to move the
core in a demolding direction of the casting; and
protruding-portion demolding means placed on both sides of the
insert core formed of a plurality of straight extending standing
plates arranged side by side, the both sides being located in a
straight extending direction of the straight extending standing
plates, to release the protruding portion from the core, wherein
control means to control operations of the product ejecting means,
the core moving means, and the protruding-portion demolding means
is configured to execute a first demolding step in which the
product ejecting means releases the casting from the movable main
die and the core moving means moves the core in association with
the casting, and a second demolding step in which the
protruding-portion demolding means alternately pushes each of the
both sides in the straight extending direction of the standing
plates forming the insert core to release the protruding portion
from the core.
[0010] In the above die casting apparatus, preferably, the
protruding-portion demolding means is configured to perform the
second demolding step by pushing the casting near the protruding
portion in the demolding direction.
[0011] In the above die casting apparatus, preferably, the core
moving means and the protruding-portion demolding means are
integrally formed by a hydraulic unit configured to separately
independently extend and contract operation rods connected to the
core and ejector pins to be pressed against a portion of the
casting near the protruding portion.
[0012] In the above die casting apparatus, preferably, the core
moving means and the protruding-portion demolding means are
integrally formed by a hydraulic unit configured to separately
independently extend and contract operation rods connected to the
core and plate-shaped ejector blocks to be pressed against the
casting near the protruding portion.
[0013] In the above die casting apparatus, preferably, the product
ejecting means includes a plurality of ejector pins or ejector
blocks fixed to an ejector plate to be moved by a hydraulic
cylinder, and the control means is hydraulic control means to drive
and control the hydraulic unit and the hydraulic cylinder.
[0014] Another aspect of the invention provides a die casting
apparatus including a fixed die and a movable die to form a cavity
for molding a casting, in which an insert core is slidably provided
in a movable main die of the movable die to form a protruding
portion of the casting, wherein the movable die includes: product
ejecting means to release the casting from the movable main die;
core moving means to move the core formed of a plurality of
separate blocks so that each of the separate blocks of the core is
moved in the demolding direction of the casting to release the
protruding portion from the insert die; and protruding-portion
demolding means to push the casting at a portion near the
protruding portion in the demolding direction, and wherein control
means to control operations of the product ejecting means, the core
moving means, and the protruding-portion demolding means is
configured to execute a first demolding step in which the product
ejecting means releases the casting from the movable main die and
the core moving means moves the core in association with the
casting, and a second demolding step in which the separate blocks
are stepwise moved relatively in an opposite direction to the
demolding direction by the core moving means with respect to the
protruding portion of the casting pushed or supported by the
protruding-portion demolding means to release the protruding
portion from the core.
[0015] In the above die casting apparatus, preferably, when the
core is configured to form the protruding portion consisting of a
plurality of straight extending standing plates arranged side by
side, the separate blocks are separated in a straight extending
direction of the standing plates.
[0016] In the above die casting apparatus, preferably, the core
moving means and the protruding-portion demolding means are
integrally formed by a hydraulic unit configured to separately
independently extend and contract operation rods connected to the
separate blocks of the core and ejector pins to be pressed against
the casing near the protruding portion.
[0017] In the above die casting apparatus, preferably, the core
moving means and the protruding-portion demolding means are
integrally formed by a hydraulic unit configured to separately
independently extend and contract operation rods connected to the
separate blocks of the core and plate-shaped ejector blocks to be
pressed against the casing near the protruding portion.
[0018] In the above die casting apparatus, preferably, wherein the
product ejecting means includes a plurality of ejector pins or
ejector blocks fixed to an ejector plate to be moved by a hydraulic
cylinder, and the control means is hydraulic control means to drive
and control the hydraulic unit and the hydraulic cylinder.
[0019] Another aspect of the invention provides a method for
releasing a casting from a die, using a die casting apparatus to
form the casting including a protruding portion, the method
including separating a movable die from a fixed die for die opening
and then demolding the casting from the movable die, wherein the
method includes: a first demolding step including moving an insert
core configured to form the protruding portion in association with
the casting to release a portion of the casting other than the
protruding portion from a movable main die of the movable die; and
a second demolding step including releasing the protruding portion
from the core, wherein when the core is configured to form the
protruding portion consisting of a plurality of straight extending
standing plates arranged side by side, the second demolding step
uses protruding-portion demolding means placed on both sides of the
core corresponding to both side positions of the standing plates in
a straight extending direction and includes alternately operating
each side of the protruding-portion demolding means to push the
casting in the demolding direction.
[0020] Another aspect of the invention provides a method for
releasing a casting from a die, using a die casting apparatus to
form the casting including a protruding portion, the method
including separating a movable die from a fixed die for die opening
and then demolding the casting from the movable die, wherein the
method includes: a first demolding step including moving an insert
core configured to form the protruding portion in association with
the casting to release a portion of the casting other than the
protruding portion from a movable main die of the movable die; and
a second demolding step including releasing the protruding portion
from the core, wherein the second demolding step uses the core
formed of a plurality of separate blocks and includes stepwise
moving the separate blocks to release the protruding portion by
each separate block.
Effects of the Invention
[0021] According to the invention, in a first demolding step, an
insert core is moved together with a casting and thus a protruding
portion exhibiting large resistance during demolding is not
released from the die. In a second demolding step, only the
protruding portion is released from the die. The resistance in each
step is thus reduced, thereby allowing entirely easy demolding of
the casting. In each step, the resistance to the product ejecting
means and the protruding-portion demolding means for releasing the
casting from the die is reduced. Thus, their breakage can be
prevented. Furthermore, the resistance generated in demolding the
protruding portion in the second demolding step is reduced, so that
stress applied at a boundary portion between the protruding portion
and a peripheral portion thereof in the casting can be reduced.
This can avoid breakage of the casting.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] FIG. 1 is a cross sectional view conceptually showing a die
casting apparatus in a first embodiment, corresponding to a die
open state after casting;
[0023] FIG. 2 is a cross sectional view conceptually showing the
die casting apparatus in the first embodiment, corresponding to a
first demolding step;
[0024] FIG. 3 is a cross sectional view conceptually showing the
die casting apparatus in the first embodiment, corresponding to a
second demolding step;
[0025] FIG. 4 is a cross sectional view conceptually showing the
die casting apparatus in the first embodiment, corresponding to
another second demolding step;
[0026] FIG. 5 is a cross sectional view conceptually showing the
die casting apparatus in the first embodiment, corresponding to
another second demolding step;
[0027] FIG. 6 is a cross sectional view conceptually showing a die
casting apparatus in a second embodiment, corresponding to a die
open state after casting;
[0028] FIG. 7 is a cross sectional view conceptually showing the
die casting apparatus in the second embodiment, corresponding to a
first demolding step;
[0029] FIG. 8 is a cross sectional view conceptually showing the
die casting apparatus in the second embodiment, corresponding to a
second demolding step;
[0030] FIG. 9 is a cross sectional view conceptually showing the
die casting apparatus in the second embodiment, corresponding to
the second demolding step;
[0031] FIG. 10 is a cross sectional view conceptually showing a die
casting apparatus in a third embodiment, corresponding to a second
demolding step;
[0032] FIG. 11 is a cross sectional view conceptually showing a
conventional die casting apparatus, corresponding to a step for
releasing a casting from a movable die;
[0033] FIG. 12 is a perspective view showing a cooling fin which is
one example of a casting;
[0034] FIG. 13 is a perspective view showing locations of ejector
pins for ejecting a casting; and
[0035] FIG. 14 is a perspective view showing locations of ejector
blocks for ejecting a casting.
REFERENCE SIGNS LIST
[0036] 1 Die casting apparatus
[0037] 10 Fixed die
[0038] 20 Movable die
[0039] 12 Movable main die
[0040] 15 Ejector plate
[0041] 16 Ejector pin
[0042] 17 Hydraulic cylinder
[0043] 21 Core
[0044] 22 Hydraulic unit
[0045] 23 Operation rod
[0046] 25, 26 Ejector pin
[0047] 28 Hydraulic control unit
[0048] 80 Casting
[0049] 81 Fin portion
MODE FOR CARRYING OUT THE INVENTION
[0050] A detailed description of a preferred embodiment of a die
casting apparatus and a method for releasing a casting from a die
or mold embodying the present invention will now be given referring
to the accompanying drawings. FIG. 1 is a cross sectional view
conceptually showing a die casting apparatus in a first embodiment,
corresponding to a die open state after casting. This die casting
apparatus 1 is configured to produce a casting 80 shown in FIG. 12
as in a conventional example, that is, a cooling fin.
[0051] The die casting apparatus 1 includes a fixed die 10 and a
movable die 20. The movable die 20 is moved by an actuator not
shown for die opening or die clamping with respect to the fixed die
10. The movable die 20 includes a movable main die 12 coupled to a
base 14. An ejector plate 15 is placed between the movable main die
12 and the base 14. To the ejector plate 15, a plurality of ejector
pins 16 are fixed to extend through the movable main die 12. A
hydraulic cylinder 17 is fixed to the base 14. An ejector rod 171
of the cylinder 17 extends through the base 14 and is connected to
the ejector plate 15. In the movable die 20, accordingly, the
hydraulic cylinder 17 makes the ejector pins 16 stick out to
release the casting 80 from the die 20.
[0052] In the movable main die 12, an insert core 21 is slidably
set. This core 21 is a block having a reversed shape of the fin
portions 81 (see FIG. 12) of the casting 80. The movable die 20 is
provided with a hydraulic unit 22. This hydraulic unit 22 includes
operation rods 23 connected to the core 21 and ejector pins 25 and
26 to release, or demold, the casting 80 so that the rods and pins
are independently extended or contracted. Accordingly, the
hydraulic unit 22 makes the core 21 slidable with respect to the
movable main die 12.
[0053] Meanwhile, the die casting apparatus 1 uses the ejector pins
25 and 26 in addition to the ejector pins 16 to release the casting
80 from the movable main die 12. The ejector pins 25 and 26 are
placed on both sides of the fin portions 81 in a longitudinal
direction (a Y direction in FIG. 12) as shown in FIG. 13. For
instance, five ejector pins 25 are provided on one side and five
ejector pins 26 are similarly provided on the opposite side of the
fin portions 81. The ejector pins 16 are arranged in predetermined
several positions more apart from the fin portions 81 than the
ejector pins 25 and 26.
[0054] When the casting 80 is to be released from the movable main
die 12, the ejector pins 16 to be extended or contracted by the
hydraulic cylinder 17 and the operation rods 23 and the ejector
pins 25 and 26 to extended or contracted by the hydraulic unit 22
are separately independently controlled for extension or
contraction. The die casting apparatus 1 is provided with a
hydraulic control unit 28 to control the hydraulic cylinder 17 and
the hydraulic unit 22.
[0055] Next, the method for releasing the casting 80 using the die
casting apparatus 1 will be explained below. FIGS. 2 and 3 stepwise
show a demolding step to be carried out by the die casting
apparatus 1, corresponding to a step following the state shown in
FIG. 1. In the die casting apparatus 1, molten metal is injected in
a cavity formed by the fixed die 10 and the movable die 20 clamped
with each other, and the molten metal is solidified, thereby
casting the casting 80. In the subsequent demolding steps,
die-opening is first performed by separating the movable die 20
from the fixed die 10 as shown in FIG. 1. At that time, the casting
80 is pushed toward the movable die 20 by ejector pins provided in
the fixed die 10, even though not illustrated. Accordingly, as
shown in FIG. 1, the casting 80 is separated from the fixed die 10
and remains fitted to the side of the movable die 20.
[0056] In the present embodiment, when the casting 80 is to be
released from the movable main die 12, demolding, or die-releasing,
is implemented in two separate steps, i.e., a first demolding step
and a second demolding step. In the first demolding step shown in
FIG. 2, firstly, the hydraulic cylinder 17 is actuated to extend,
thereby making the ejector pins 16 eject and release the casting 80
from the movable main die 12. At that time, the hydraulic unit 22
makes the operation rods 23 extend or stretch by the same stroke as
the hydraulic cylinder 17, thereby moving the core 21 together with
the casting 80 pushed by the ejector pins 16. In this first
demolding step, therefore, the casting 80 is demolded from the
movable main die 12 but the fin portions 81 still remain fitted in
the core 21.
[0057] In the second demolding step shown in FIG. 3, therefore, the
hydraulic unit 22 is then actuated to extend the ejector pins 25
and 26 to press against the casting 80. At that time, since the
stroke of each operation rod 23 is not changed and thus the core 21
is left unmoved. Therefore, the casting 80 is ejected by the
ejector pins 25 and 26 in the demolding direction, so that the fin
portions 81 are separated from the core 21. The entire demolding is
completed. In this demolding step, a robot arm not shown follows
the casting 80. Accordingly, the released casting 80 is grasped by
the robot arm so as not to drop down after demolding, and conveyed
to a next step.
[0058] In the first demolding step shown in FIG. 2, accordingly,
the core 21 is moved in the demolding direction and the fin
portions 81 having large resistance to releasing are not demolded,
so that the resistance to the ejector pins 16 can be reduced. In
the second demolding step, similarly, only the fin portions 81 are
demolded, so that the resistance to the ejector pins 25 and 26 can
be reduced. Since the resistance in each step is small, it is
possible to prevent the ejector pins 16 and ejector pins 25 and 26
from breaking or bending. Furthermore, the reduced resistance to
the ejector pins 25 and 26 enables reduction in the stress applied
on the corner 85 at a boundary between the fin portions 81 and the
flat plate portion 82 on which stress is likely to concentrate.
This can prevent breakage of the casting 80 during die-releasing,
or demolding.
[0059] In the second demolding step shown in FIG. 3, meanwhile, the
ejector pins 25 and 26 are synchronously extended, or stretched.
Alternatively, the pins may be independently extended and
contracted. FIGS. 4 and 5 are diagrams showing another second
demolding step to be performed instead of the method shown in FIG.
3. In this second demolding step, as shown in FIG. 4, firstly, the
hydraulic cylinder 17 is actuated to move back the ejector pins 16
through the ejector plate 15 into the movable main die 12. The
ejector pins 16 thus separate from the casting 80. Then, the
hydraulic unit 22 is operated to extend and contract the ejector
pins 25 and 26 separately while maintaining the stroke of the
operation rods 23.
[0060] To be concrete, as shown in FIG. 4, only the ejector pins 25
located on one side of the fin portions 81 are stretched as shown
in FIG. 4 to press against the casting 80. Successively, as shown
in FIG. 5, the ejector pins 25 are contracted to separate from the
casting 80 and the ejector pins 26 are stretched to press against
the casting 80. In this manner, the fin portions 81 are released
from the core 21 by alternately displacing the ends of the fin in
the longitudinal direction. According to this demolding method,
when the ejector pins 25 or ejector pins 26 push out the casting
80, each pin applies a force in a direction at an angle to the
demolding direction, thereby increasing a force in a shear
direction between the core 21 and the fin portions 81, thus
facilitating demolding. Furthermore, a force further acts in an
oblique direction, increasing the clearance between the core 21 and
the fin portions 81. This can reduce friction force between
them.
[0061] Accordingly, the resistance to the ejector pins 25 and 26 is
reduced, which can prevent the ejector pins 16 and the ejector pins
25 and 26 from breaking or bending. It is further possible to
reduce the stress applied on the corner 85 of the casting 80 at
which the stress is likely to concentrate and prevent breakage
during demolding. The die casting apparatus 1 in the present
embodiment can achieve the above effects by a hydraulic mechanism
conventionally used, not by a special structure, without increasing
costs. The apparatus itself is also easy to handle. In the die
casting apparatus 1, furthermore, the ejector pins 16, 25, and 26
do not directly push the fin portions 81. This enables manufacture
of thin fins and does not deform such fins during demolding.
[0062] In the case shown in FIG. 5, the ejector pins 25 are
contracted. Alternatively, the ejector pins 25 may be left extended
when the ejector pins 26 are extended. The ejector pins 25 and 26
may be extended alternately and repeatedly, e.g., in steps of
0.1-mm stroke, and subsequently extended synchronously as in the
method shown in FIG. 3.
Second Embodiment
[0063] A second embodiment of a die casting apparatus according to
the invention will be explained below. FIG. 6 is a cross sectional
view conceptually showing the die casting apparatus of the second
embodiment, corresponding to a die open state after casting. This
die casting apparatus 2 is also configured to produce a cooling
fin, i.e., the casting 80 shown in FIG. 12. Since this die casting
apparatus 2 is identical in structure to the die casting apparatus
1 of the first embodiment, similar or identical parts are explained
with the same reference signs as those in the first embodiment.
[0064] The die casting apparatus 2 includes the fixed die 10 and a
movable die 30. The movable die 30 includes the movable main die 12
coupled to the base 14 and ejector pins 16 to be extended or
contracted by the hydraulic cylinder 17. In the present embodiment,
a split core 31 is provided in the movable main die 12 and is moved
by a hydraulic unit 32. The core 31 consists of a first block 301
and a second block 302 which are connected respectively to
operation rods 33 and 34 to move independently. The first block 301
and the second block 302 are two blocks separated in a longitudinal
direction of the fin. Alternatively, they may be blocks separated
in a direction perpendicular to the fin or more than two separate
blocks.
[0065] The hydraulic unit 32 is also provided with ejector pins 35.
The ejector pins 35 correspond to the ejector pins 25 and 26 shown
in FIG. 13 and are placed, several pins each, on both sides of the
fin portions 81 in the longitudinal direction. The ejector pins 16
are placed at predetermined several positions more apart from the
fin portions 81 than the ejector pins 35. The hydraulic cylinder 17
and the hydraulic unit 32 are connected to the hydraulic control
unit 28 to control extension and contraction of the ejector pins 16
and 35 and the operation rods 33 and 34.
[0066] The demolding method using the above die casting apparatus 2
will be explained below. FIGS. 7 to 9 stepwise show a demolding
step to be carried out by the die casting apparatus 2,
corresponding to a step following the state shown in FIG. 6. In the
die casting apparatus 2, molten metal is injected in a cavity
formed by the fixed die 10 and the movable die 30, and the molten
metal is solidified, thereby casting the casting 80. In the
subsequent demolding steps, die-opening is performed by separating
the movable die 30 from the fixed die 10 as shown in FIG. 6. At
that time, the casting 80 is separated from the fixed die 10 and
remains fitted to the side of the movable die 30 as shown in FIG.
6.
[0067] Demolding of the casting 80 from the movable die 30 is first
performed in the first demolding step as shown in FIG. 7. In the
first demolding step, the hydraulic cylinder 17 is actuated to
extend, thereby making the ejector pins 16 eject and release the
casting 80 from the movable main die 12. At that time, the
hydraulic unit 32 makes the operation rods 33 and 34 extend or
stretch by the same stroke as the hydraulic cylinder 17, thereby
moving the core 31 together with the casting 80 pushed by the
ejector pins 16. Therefore, the fin portions 81 of the casting 80
still remain fitted in the core 31. Then, the second demolding step
is performed to release the fin portions 81.
[0068] In the second demolding step, as shown in FIG. 8, the
ejector pins 35 are extended or stretched to push and move the
casting 80. At that time, the stroke of the operation rod 33 is not
changed and only the other operation rod 34 is extended or
stretched to move the second block 302 in association with movement
of the casting 80 by the ejector pins 35. Accordingly, the fin
portions 81 are first released from the first block 301 of the core
31. Thereafter, as shown in FIG. 9, the ejector pins 35 are further
extended to move the casting 80 while the stroke of the operation
rod 34 is kept. Thus, the fin portions 81 of the casting 80 are
separated from the second block 302 of the core 31. The entire
demolding is completed. The released casting 80 is grasped by a
robot arm not shown so as not to drop down and is conveyed to a
next step.
[0069] The second demolding step mentioned above shows the method
for extending the ejector pins 35 while the first block 301 and the
second block 302 are stopped. Conversely to the above method, it
may be arranged so that the ejector pins 35 are stopped in an
extended state and the operation rods 33 and 34 are stepwise
contracted separately to demold the fin portions 81. Accordingly,
the ejector pins 35 in this method function to push out the casting
80, thereby releasing the casting 80 from the movable main die 12
in the first demolding step, and function to support the casting 80
without changing the stroke in the second demolding step.
[0070] In the die casting apparatus 2 of the present embodiment,
the core 31 is moved in the demolding direction so that the fin
portions 81 are not demolded in the first demolding step, and then
only the fin portions 81 are demolded in the second demolding step.
This can reduce the resistance to die releasing in each step. Since
the resistance to the ejector pins 16 and 35 during demolding is
reduced, it is possible to prevent the ejector pins 16 and 35 from
breaking or bending. In the second demolding step, especially,
demolding is performed stepwise by the split core 31, so that
resistance during demolding in each block is made small.
Accordingly, this reduces the stress applied on the corner 85
present at a boundary between the fin portions 81 and the flat
plate portion 82 on which stress is likely to concentrate. This can
prevent breakage of the casting 80 during demolding. In the die
casting apparatus 2, furthermore, the ejector pins do not directly
push the fin portions 81. This enables manufacture of thin fins and
does not deform the fins during demolding.
Third Embodiment
[0071] A third embodiment of a die casting apparatus of the
invention will be explained below. FIG. 10 is a cross sectional
view conceptually showing the die casting apparatus of the third
embodiment, corresponding to a step to release a casting from a
movable die. This die casting apparatus 3 is also configured to
manufacture a cooling fin, that is, the casting 80 shown in FIG.
12. This die casting apparatus 3 is also identical in structure to
the die casting apparatus 1 of the first embodiment and thus
similar or identical parts are explained with the same reference
signs as those in the first embodiment.
[0072] The die casting apparatus 3 includes a movable die 40 and a
fixed die not shown. The movable die 40 includes the movable main
die 12 fixed to the base 14 and ejector pins 16 to be extended or
contracted by the hydraulic cylinder 17. The movable main die 12 is
provided with the slidable core 21 connected to the operation rods
23 of the hydraulic unit 22. Meanwhile, the die casting apparatus 3
is configured to stepwise perform demolding using the ejector pins
16 and demolding using a robot arm for grasping the casting 80.
FIG. 10 illustrates a hand portion of a robot arm 50 used to grasp
the casting 80 to prevent the casting 80 from dropping down and
convey the casting 80 to a next step.
[0073] In the die casting apparatus 3, the casting 80 is
die-released, or demolded, in the following manner. The movable die
40 is separated from the fixed die for die opening, and then the
first demolding step of the casting 80 is performed in the movable
die 40. FIG. 10 shows a stage shifting from the finished first
demolding step to the next second demolding step. In the first
demolding step, the hydraulic cylinder 17 is actuated to extend,
thereby moving the ejector plate 15 to stick out the ejector pins
16, thereby ejecting the casting 80 out of the movable main die 12
as shown in FIG. 10. At that time, the hydraulic unit 22 causes the
operation rods 23 to extend or stretch by the same stroke as the
hydraulic cylinder 17, thereby moving the core 21 together with the
casting 80 pushed by the ejector pins 16 in the demolding
direction.
[0074] Accordingly, the fin portions 81 of the casting 80 still
remain fitted in the core 21 and then the fin portions 81 are
demolded in the following second demolding step. In the second
demolding step, the fin portions 81 are pulled out by the robot arm
50. The robot arm 50 moves the casting 80 in the fin longitudinal
direction. Thus, the fin portions 81 of the casting 80 are
separated from the core 21. The entire demolding is completed.
[0075] As above, the die casting apparatus 3 of the present
embodiment is also operated to move the core 21 out of the die and
the fin portions 81 are not demolded in the first demolding step
and then only the fin portions 81 are demolded in the second
demolding step. This can reduce the demolding resistance in each
step. The resistance to the ejector pins 16 during demolding is
reduced, so that the ejector pins 16 are prevented from breaking or
bending. In particular, since the casting 80 is moved in the fin
longitudinal direction in the second demolding step, this can
reduce the stress applied on the corner 85 at a boundary between
the fin portions 81 and the flat plate portion 82 on which the
stress is likely to concentrate, thereby preventing breakage of the
casting 80 in during demolding. Furthermore, the ejector pins do
not directly push the fin portions 81. This enables manufacture of
thin fins and does not deform the fins.
[0076] The above explanations are given to the die casting
apparatus and the method for releasing the casting from the die
according to the invention. However, the present invention is not
limited to the above embodiments and may be embodied in other
specific forms without departing from the essential characteristics
thereof. For instance, in the first and second embodiments, the fin
portions 81 are demolded by use of the ejector pins 25 and 26 and
the ejector pins 35 as shown in FIG. 4. Instead of the ejector pins
25 and 26 and the ejector pins 35, it may be configured so that
plate-shaped ejector blocks 45 shown in FIG. 14 are moved in and
out by a hydraulic unit. The casting to be produced by the die
casting apparatus is not limited to the cooling fin. The cooling
fin is also not limited to a straight fin depending to the
embodiments. For example, a meandering or zigzag fin or pin fin may
be adopted.
[0077] In the second demolding step executed by the die casting
apparatus 1 of the first embodiment, the stroke of each ejector pin
25 and 26 may be controlled by detecting resistance by a load cell.
In the third embodiment, there is not provided pins to push the
casting 80 in the second demolding step. Alternatively, the third
embodiment may include the ejector pins 25 and 26 as in the first
embodiment so that the fin portions 81 are displaced and then
pulled by the robot arm 51. Furthermore, a means for imparting
vibrations to an insert core and a casting may be added.
* * * * *