U.S. patent application number 15/663008 was filed with the patent office on 2018-02-01 for manufacturing apparatus for metal molded body.
The applicant listed for this patent is AIDA ENGINEERING, LTD.. Invention is credited to Masaharu MURAMATSU, Shogo SHIBASAKI, Masataka YAHARA.
Application Number | 20180029112 15/663008 |
Document ID | / |
Family ID | 59752196 |
Filed Date | 2018-02-01 |
United States Patent
Application |
20180029112 |
Kind Code |
A1 |
MURAMATSU; Masaharu ; et
al. |
February 1, 2018 |
MANUFACTURING APPARATUS FOR METAL MOLDED BODY
Abstract
There is provided a manufacturing apparatus for a metal molded
body. The manufacturing apparatus includes: a die having an
elongated shape in plan view; and a plurality of pairs of thrust
units disposed along a wall surface with the die disposed
therebetween from both sides of the die, wherein the pairs of
thrust units have electromagnetic coils that generate reverse
traveling magnetic fields, and the pairs of thrust units arranged
in a longitudinal direction are set so as to generate the reverse
traveling magnetic fields for each series composed of a single
thrust unit or a plurality of the thrust units.
Inventors: |
MURAMATSU; Masaharu;
(Kanagawa, JP) ; SHIBASAKI; Shogo; (Kanagawa,
JP) ; YAHARA; Masataka; (Kanagawa, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
AIDA ENGINEERING, LTD. |
Kanagawa |
|
JP |
|
|
Family ID: |
59752196 |
Appl. No.: |
15/663008 |
Filed: |
July 28, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B22D 11/115 20130101;
B22D 11/003 20130101; B22D 11/16 20130101; B22D 27/02 20130101 |
International
Class: |
B22D 11/115 20060101
B22D011/115; B22D 11/16 20060101 B22D011/16; B22D 11/00 20060101
B22D011/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 28, 2016 |
JP |
2016-148972 |
Claims
1. A manufacturing apparatus for a metal molded body, the
manufacturing apparatus comprising: a die having an elongated shape
in plan view; and a plurality of pairs of thrust units disposed
along a wall surface with the die disposed therebetween from both
sides of the die, wherein the pairs of thrust units have
electromagnetic coils that generate reverse traveling magnetic
fields, and the thrust units arranged in a longitudinal direction
are set so as to generate reverse traveling magnetic fields for
each single thrust unit or each series composed of a plurality of
the thrust units.
2. The manufacturing apparatus for a metal molded body according to
claim 1, comprising a control circuit that switches directions of
traveling magnetic fields of the electromagnetic coils such that
the thrust units arranged in the longitudinal direction generate
reverse traveling magnetic fields for each desired number of the
thrust units.
3. The manufacturing apparatus for a metal molded body according to
claim 1, wherein a whole or a part of the die is curved in plan
view.
4. The manufacturing apparatus for a metal molded body according to
claim 2, wherein a whole or a part of the die is curved in plan
view.
5. The manufacturing apparatus for a metal molded body according to
1, further comprising a thrust unit that causes an obliquely
vertical traveling magnetic field, in addition to the thrust unit
that causes a horizontal traveling magnetic field.
6. The manufacturing apparatus for a metal molded body according to
2, further comprising a thrust unit that causes an obliquely
vertical traveling magnetic field, in addition to the thrust unit
that causes a horizontal traveling magnetic field.
7. The manufacturing apparatus for a metal molded body according to
3, further comprising a thrust unit that causes an obliquely
vertical traveling magnetic field, in addition to the thrust unit
that causes a horizontal traveling magnetic field.
8. The manufacturing apparatus for a metal molded body according to
4, further comprising a thrust unit that causes an obliquely
vertical traveling magnetic field, in addition to the thrust unit
that causes a horizontal traveling magnetic field.
Description
BACKGROUND OF THE INVENTION
Field of the Invention
[0001] The present invention relates to a manufacturing apparatus
for a metal molded body. More specifically, the present invention
relates to an apparatus for suppressing growth of a metal crystal
by electromagnetically stirring melted metal such as aluminum
alloy, cooling the melted metal while discharging residual gas as a
source of a mold cavity, and producing a tough metal molded
body.
Description of Related Art
[0002] Description will be made by taking an example of aluminum as
metal. In order to produce a precise aluminum material, it is
essential that aluminum as a material has a fine crystal structure,
and does not have defects such as a mold cavity therein. In order
to produce such a material, molten aluminum is transferred to a die
of a stirrer (manufacturing apparatus for a metal molded body), and
growth of a crystal structure is prevented by stirring and cooling
the molten aluminum in the die, so that a dense material is
produced. Mechanical force is sometimes used as stirring force, but
an electromagnetic force method capable of performing stirring in a
non-contact manner is preferable in consideration of abrasion and
the like of a stirring rod.
[0003] In order to perform stirring by electromagnetic force, a
large number of coils are arranged along a wall surface (indicating
an inner wall surface) of the die, a magnetic field which travels
along the wall surface by a group of these coils is formed. An
induced current is generated in the molten aluminum by the
traveling magnetic field, electromagnetic force (Lorentz force) is
generated by the current and the changing magnetic field, and the
molten metal moves along the wall surface. Then, the movement of
the molten metal along the wall surface reaches the center, so that
stirring as a whole proceeds. This stirring work is continued until
the metal is solidified. There are a case where the solidified
metal is used as a final molded body with no change, and a case
where the solidified metal is transposed to a press forming die to
be pressurized and formed. The aluminum material thus completed has
strong strength, and has less defects such as a mold cavity.
Therefore, such an aluminum material is reliable as a part
material.
[0004] In general, in an aluminum rabble furnace, a molten
substance is stirred in a cylindrical melting pot, as described in
JP 5352236 B1, JP 2009-74103 A, and JP 2007-144501 A. Therefore,
the electromagnetic stirring apparatus has a cylindrical shape,
similarly to a motor stator. However, for example, in a case where
an elongated structure is made of aluminum, the shape of a stirring
die is elongated. In the cylindrical rabble furnace, the volume of
the furnace becomes huge, and huge excitation force is required,
which is irrational. Therefore, a linear type stirring apparatus
described in JP 2006-289448 A is known.
[0005] As a structure of a thrust section of a linear type stirring
apparatus, JP 2006-289476 A, "Electromagnetic Coil Designed by
Magneto-Hydro-Dynamic Simulation", shinnittetsu giho vol. 379, and
"Development of a Simulation Model for Electromagnetic Stirring in
Melting Furnace, Furukawa-sky Review" No. 3, 2007" are known.
SUMMARY OF THE INVENTION
Problem to be Solved by the Invention
[0006] A vehicle body structure and the like are generally thin and
long. In addition, such structures are often bent. Accordingly, in
the circular stirring apparatus, as described above, the furnace
volume is large, and excitation force (AT) for operation becomes
extremely strong, and therefore handling is difficult. Therefore,
such a linear type stirring apparatus described in JP 2006-289448
A, and JP 2006-289476 A, related to a continuous casting apparatus
is applied. However, the linear type stirring apparatus has an
elongated structure, and has a long acceleration distance (refer to
FIG. 1). Such a long acceleration distance increases the speed of
molten metal, and a phenomenon that the molten metal runs on a wall
surface of a die at a folded part or turning position having a
small radius of curvature (refer to an end 18 of FIG. 1), or runs
over the wall surface to fall to the outside is generated. In
particular, the die is provided with a draft angle, and therefore
the molten metal more easily runs on the wall surface.
[0007] In order to suppress such a run-over phenomenon, when
excitation force is reduced, traveling becomes moderate, and the
run-over is suppressed. On the other hand, stirring efficiency is
lowered, and a metal molded body formed of fine crystals cannot be
efficiently manufactured. The present invention solves such a
problem, and an object of the present invention is to provide a
manufacturing apparatus for a metal molded body capable of
performing efficient stirring by using an elongated die, and
suppressing run-on or run-over of molten metal to a die wall
surface.
Means to Solve the Problem
[0008] A manufacturing apparatus for a metal molded body of the
present invention includes: a die having an elongated shape in plan
view; and a plurality of pairs of thrust units disposed along a
wall surface with the die disposed therebetween from both sides of
the die, wherein the pairs of thrust units have electromagnetic
coils that generate reverse traveling magnetic fields with each
other and the thrust units arranged in a longitudinal direction are
set so as to generate reverse traveling magnetic fields for each
single thrust unit or each series composed of a plurality of the
thrust units.
[0009] Such a manufacturing apparatus for a metal molded body may
include a control circuit that switches the traveling magnetic
fields of the electromagnetic coils such that the thrust units
arranged in the longitudinal direction generate the reverse
traveling magnetic fields for each desired number of the thrust
units. Additionally, a whole or a part of the die may be curved in
plan view. Furthermore, the manufacturing apparatus for a metal
molded body preferably includes a thrust unit that causes an
obliquely vertical traveling magnetic field, in addition to the
thrust unit that causes a horizontal traveling magnetic field.
Effect of the Invention
[0010] In the manufacturing apparatus for a metal molded body of
the present invention, a partial circulation flow of molten metal
can be generated in the die by the traveling magnetic fields of the
series composed of a pair of or a plurality of pairs of the thrust
units disposed along the wall surface with the die disposed
therebetween. That is, a flow in one direction is generated by the
single or the plurality of thrust units disposed along one wall
surface, and a flow in the other direction is generated by the
single or the plurality of thrust units disposed along the other
wall surface. Then, in an end of each series, a flow is generated
in the die crossing direction. Therefore, a flow that circulates
for each thrust unit is generated. The traveling direction of the
magnetic field of a certain series of the thrust units, and the
traveling direction of the magnetic field in the other series of
the thrust units adjacent to the certain series of the thrust units
are reversed from each other, and therefore the directions of the
circulation flows are reversed. For example, when a clockwise
circulation flow is generated in the series of the pair of thrust
units, a counterclockwise circulation flow is generated in the
other series of pair of thrust units in the adjacent to the series
of the pair of thrust units.
[0011] Therefore, in each of the ends of the series of the thrust
units, the flow along the wall surface is divided, and a node is
formed in the flow. Therefore, an accelerated flow reduces the
speed at a portion of the node or joint, and migration energy is
converted into stirring energy. Therefore, running on the wall
surface and running over the wall surface are suppressed.
Additionally, at the portion of the node, the molten metal flowing
from one of both sides collides with the molten metal flowing from
the other side, or is divided, and therefore the molten metal is
more efficiently stirred.
[0012] In a case where such a manufacturing apparatus for a metal
molded body includes the control circuit that switches the
directions of the traveling magnetic fields of the electromagnetic
coils such that the thrust units arranged in the longitudinal
direction generate the reverse traveling magnetic fields for each
desired number of the thrust units, suitable stirring action and
flow rate can be selected in accordance with the kind of metal. In
a case where the die is curved in plan view, the curved metal
molded body can be efficiently produced, and suppression of the
above run-on and run-over can be attained similarly to the
above.
[0013] In a case where the manufacturing apparatus includes the
thrust unit that causes the obliquely vertical traveling magnetic
field, in addition to the thrust unit that causes the horizontal
traveling magnetic field, molten metal obliquely flows, and
therefore a laminar flow commutates, and can be more efficiently
stirred, and crystal grains can be made fine.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1A is a plan view illustrating a manufacturing
apparatus for a metal molded body according to an embodiment of the
present invention, and FIG. 1B is an enlarged view of an essential
part.
[0015] FIG. 2 is a II-II line sectional view of the manufacturing
apparatus of FIG. 1A.
[0016] FIG. 3A and FIG. 3B are a schematic plan view and a
schematic side view illustrating thrust units according to an
embodiment (core back winding method) of the present invention,
respectively.
[0017] FIG. 4A and FIG. 4B are a schematic plan view and a coil
connection diagram illustrating thrust units according to another
embodiment (slot winding method) of the present invention,
respectively.
[0018] FIG. 5 is a plan view illustrating an example of wire
connection when a plurality of the thrust units of FIG. 3A and FIG.
3B are combined.
[0019] FIG. 6 is a plan view illustrating a manufacturing apparatus
for a metal molded body according to another embodiment of the
present invention.
[0020] FIG. 7A and FIG. 7B are a front view and a plan view
illustrating thrust unit that changes a flow of molten metal
according to an embodiment of the present invention, respectively
(illustration of the shapes of coil sides are omitted).
[0021] FIG. 8A to FIG. 8D each are a plan view illustrating a
manufacturing apparatus for a metal molded body according to yet
another embodiment of the present invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0022] A manufacturing apparatus (electromagnetic stirring
apparatus) 10 for a metal molded body illustrated in FIG. 1A
includes an elongated die 11 that is curved in an arc shape in plan
view, and a plurality of pairs of thrust units 12 that are disposed
along a wall surface of the die with the die disposed therebetween.
Each thrust unit 12 includes cores 13, and coils 14 that are wound
around the cores 13, as illustrated in FIG. 1B. In this embodiment,
two sets each obtained by winding the three coils 14 around the one
core 13 are connected through a wedge shaped magnetic body 15 for
curvature adjustment at an angle, and are made to be one unit. In
FIG. 1A, the wedge shaped magnetic bodies are omitted.
[0023] The die 11 has a substantially U-shaped cross-section
including a bottom plate 16, and side walls 17 rising from both
ends of the bottom plate, as illustrated in FIG. 2, for example. In
general, the depth of the die 11 is deeper than the width.
Additionally, the side walls 17 are provided with draft angles, and
expand toward upper ends. The die 11 is formed of metal having heat
resistance enough to withstand a high temperature of molten metal,
and having low magnetic permeability (for example, stainless
steel), ceramics, or the like. The thrust units 12 are obliquely
disposed in parallel to the wall surface with slight gaps G between
the wall surface (inner wall surface) of the inclined side walls 17
and the thrust units 12.
[0024] The size and the shape of the die 11 depend on the size and
the shape of a member to be molded. As illustrated in FIG. 1A, ends
18 of the die 11 each have an arc shape such that the direction of
molten metal can be smoothly changed. In this embodiment, the right
and left side walls 17 are each curved. The right and left side
walls 17 have a common center of the curvature, and have almost the
same width in the length direction. The thrust units 12 disposed
along the side walls 17 are disposed so as to be curved or bent
similarly, gaps G (refer to FIG. 2) with the side walls (inner side
walls) 17 are as small as possible, and are constant along the
longitudinal direction.
[0025] FIG. 3A and FIG. 3B each illustrate a thrust unit 12 by a
"core back wounding method" among a basic shape. Each thrust unit
12 includes the core 13 having a comb-tooth shape, and the coils 14
that are wound between teeth of the core. The core 13 is composed
of a rectangular column shaped yoke (core back) 19, and teeth 21
having ends fixed to dovetail-shaped grooves 20 formed in the yoke.
The number of the teeth 21 is seven, the number of the coils 14 to
be wound around the yoke between the teeth is six, and all the
coils are wound in the same direction. Therefore, in a case where a
current enters from an initially wound coil, and a case where a
current enters from a finally wound coil, the polarities are
reverse. Slots 22 between the teeth 21 are filled with the coils
(coil conductors) 14. The slots 22 are opened toward the die 11
through slits 23 that are elongated openings. The yoke 19 and the
teeth 21 are each formed by superimposing a large number of thin
sheets of silicon steel sheets. The yoke and the teeth may be
integrated.
[0026] FIG. 4A and FIG. 4B illustrates a thrust unit 12A by
"inter-slot winding method" among a basic shape. In this method,
the thrust unit 12A includes the core 13 having a comb-teeth shape
including the yoke 19 and a plurality of the teeth 21, and the
coils 14 each wound around a plurality of the teeth 21. The slots
22a to 22f are filled with the coils (coil conductors) 14. The
coils 14 are composed of three kinds of coils 14u, 14v, 14w
corresponding to a U-phase, a V-phase, and a W-phase of three-phase
current (AC), respectively. A U-phase coil 14u passes through a
leftmost slot 22a and a fourth slot 22d to be wound around three
teeth between the leftmost slot and the fourth slot.
[0027] Similarly, a V-phase coil 14v passes through a third slot
22c and a sixth slot 22f to be wound around three teeth between the
third slot and the sixth slot. A W-phase coil 14w passes through a
second slot 22b and a fifth slot 22e to be wound around three teeth
between the second slot and the fifth slot. These three kinds of
coils 14u, 14v, 14w are overlapped to be intersect with each other
on the lateral side of the core 13, as illustrated in FIG. 4B.
Symbol 0 denotes a neutral point of a three-phase current. In the
thrust unit 12A by such an "inter-slot winding method", the coils
14u to 14w are not wound the core back 19, and therefore the core
back 19 can be used to fix the thrust unit.
[0028] FIG. 5 illustrates wire connection in which three thrust
units 12 are lined on one side of the die 11. A power source is a
three-phase current. Symbol 0 is a neutral point. When three-phase
current U, W, V are sequentially connected to coils of terminal
symbols R, S, T, a magnetic flux advances from the left to the
right (refer to an arrow .phi.1). When a phase order is changed and
the three phase current are connected to the U-phase, the V-phase,
the W-phase in order, a magnetic flux advances from the right to
the left (the arrow .phi.2 direction). That is, in FIG. 5, in a
left end unit 12a, the W-phase is connected to a winding finish end
of a coil denoted by symbol w1-, and the V-phase is connected to a
winding start end of a coil denoted by symbol v1+. In an central
unit 12b, the V-phase is connected to a winding finish end of a
coil denoted by symbol w3-, the W-phase is connected to a winding
start end of a coil denoted by symbol v3+, the V-phase and the
W-phase are reverse. Furthermore, connection in a right end unit
12c is similar to the connection in the left end unit 12a, and
therefore a magnetic flux advances in the arrow .phi.3 direction
similar to the arrow .phi.1.
[0029] When such thrust units are disposed on both side of a pot,
as illustrated in FIG. 6, the advancing directions of magnetic
fluxes of units 12a, 12b, 12c on the near side of the die 11 and
the advancing directions of magnetic fluxes of units 12d, 12e, 12f
on the far side are made reverse. Consequently, in a case where the
direction of a vortex Q1 of molten metal caused by a pair of the
left end units 12a, 12d is counterclockwise, a clockwise vortex Q2
is generated in a pair of the central units 12b, 12e. Furthermore,
a counterclockwise vortex Q3 is generated again in a pair of the
right end units 12c, 12f.
[0030] Therefore, the directions of the circulating vortexes are
reverse for each set of the adjacent units, and therefore in the
ends of the thrust units, a flow along the wall surface is divided,
so that nodes 24a, 24b are formed in the flow. Therefore, an
accelerated flow reduces the speed at portions of the node 24a and
node 24b, and migration energy is converted into stirring energy.
Therefore, also when molten metal flows into the arc shapes of the
ends, or also when the side walls 17 are curved as illustrated in
FIG. 1A, running onto the wall surface of the side walls 17, and
running over the side walls 17 are suppressed. Additionally, at the
portions of the node 24a and the node 24b, the molten metal flowing
from one of the both sides collides with the molten metal flowing
from the other side, and furthermore, an integrated flow is
divided, and therefore the molten metal is more efficiently
stirred.
[0031] In the embodiment, the thrust units are arranged in parallel
to the inner side walls of the die (means that a void is uniform),
a vortex generates horizontally. However, for example, as
illustrated in FIG. 7A and FIG. 7B, a thrust unit 25 that generates
a vertically inclined flow P can be combined. Two slots 22 of the
thrust unit 25 are formed with slits 23 provided with an inclined
angle (skew) which retreats toward the lower part. By such skew, a
vertical oblique flow P generates in the molten metal, and a
laminar flow of the molten metal in the die commutates. Therefore
residual gas venting is facilitated, more efficient stirring is
attained, and therefore it is possible to make crystal grains
fine.
[0032] Such skew can be formed by obliquely machining the slits 23,
when electromagnetic steel plates are stuck to perform machining on
the slots 22 by wire cutting. The slots 22 are filled with the
coils (coil conductor) 14, but are omitted in FIG. 7B. Reference
numeral 26 in FIG. 7B denotes a wedge or plate for holding the
coils 14 in the slot 22.
[0033] In the embodiment, the advancing direction of the magnetic
field is reversed for each thrust unit 12, and the direction of
vortexes Q1, Q2 of molten metal are reversed for each pair of the
thrust units 12 as illustrate in FIG. 8A. However, the two or three
thrust units as illustrated in FIG. 8B and FIG. 8C, or the four or
more thrust units as illustrated in FIG. 8D can form a "series" in
which the advancing direction of a magnetic field is the same, and
can be installed such that the vortexes are reversed for each
series. In this case, the number or nodes are reduced, and
therefore stirring action is reduced, but the speed of each vortex
is increased. Accordingly, suitable stirring action and vortex
speed can be set in accordance with the kind of metal to be
manufactured.
[0034] Furthermore, a control circuit that switches, for each
thrust unit, the direction of a current that flows into
electromagnetic coils of the thrust unit may be provided, and the
direction of the traveling magnetic field may be changed for every
arbitrary n thrust units such as every single thrust unit, and
every two thrust units, and the directions of vortexes may be able
to be reversed. In such a manufacturing apparatus for a metal
molded body capable of changing wiring of the coils of the thrust
units, suitable stirring action and vortex speed can be selected in
accordance with the kind of metal, and a metal molded body can be
efficiently manufactured.
* * * * *