U.S. patent application number 16/865530 was filed with the patent office on 2020-08-20 for device and method for continuously removing impurities from molten metal.
The applicant listed for this patent is Kenzo TAKAHASHI. Invention is credited to Kenzo TAKAHASHI.
Application Number | 20200261970 16/865530 |
Document ID | 20200261970 / US20200261970 |
Family ID | 1000004844575 |
Filed Date | 2020-08-20 |
Patent Application | download [pdf] |
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United States Patent
Application |
20200261970 |
Kind Code |
A1 |
TAKAHASHI; Kenzo |
August 20, 2020 |
DEVICE AND METHOD FOR CONTINUOUSLY REMOVING IMPURITIES FROM MOLTEN
METAL
Abstract
A device for continuously removing impurities from molten metal
includes a molten metal flow path body, an inlet-side closed end
plate and an outlet-side closed end plate are provided in the
molten metal flow path body so as to form an impurity removal
space, an electrode device composed of an inlet-side electrode and
an outlet-side electrode that face each other in a longitudinal
direction of the molten metal flow path body, a magnetic field
device composed of a pair of permanent magnets that face each other
in a width direction, sandwich the impurity removal space, and an
urging device composed of the electrode device and the magnetic
field device applies a Lorentz force downward to molten metal in
the impurity removal space so as to increase a density of the
molten metal and cause impurities in the molten metal to rise up to
a surface of the molten metal.
Inventors: |
TAKAHASHI; Kenzo;
(Shiroi-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
TAKAHASHI; Kenzo |
Shiroi-shi |
|
JP |
|
|
Family ID: |
1000004844575 |
Appl. No.: |
16/865530 |
Filed: |
May 4, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/JP2018/031232 |
Aug 23, 2018 |
|
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16865530 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B22D 11/115 20130101;
B22D 11/045 20130101; B22D 41/56 20130101; B22D 27/02 20130101;
B22D 11/119 20130101 |
International
Class: |
B22D 11/115 20060101
B22D011/115; B22D 11/045 20060101 B22D011/045; B22D 27/02 20060101
B22D027/02; B22D 41/56 20060101 B22D041/56; B22D 11/119 20060101
B22D011/119 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 15, 2017 |
JP |
217-220376 |
Claims
1. A device for continuously removing impurities from molten metal,
which sends electrically conductive molten metal to a metal product
manufacturing device in a next stage, the device comprising: a
molten metal flow path body having a molten metal flow path for
flowing electrically conductive molten metal that has flown from
outside toward the metal product manufacturing device; an
inlet-side closed end plate and an outlet-side closed end plate
that are provided in the molten metal flow path body so as to
partition a front and a rear of the molten metal flow path and form
an impurity removal space; an electrode device composed of an
inlet-side electrode and an outlet-side electrode that are provided
in the impurity removal space, face each other in a longitudinal
direction in which molten metal flows, and can be put into
electrical contact with molten metal in the impurity removal space;
and a magnetic field device composed of a pair of permanent magnets
that are provided outside the molten metal flow path forming body,
face each other in a width direction intersecting the longitudinal
direction, sandwich the impurity removal space of the molten metal
flow path forming body in the width direction, have opposite poles
facing each other, and can form a magnetic field in molten metal in
the impurity removal space, wherein the electrode device and the
magnetic field device constitute an urging device that can apply a
Lorentz force downward to molten metal in the impurity removal
space so as to increase a density of the molten metal and cause
impurities in the molten metal to rise up to a surface of the
molten metal.
2. The device for continuously removing impurities from molten
metal according to claim 1, wherein a power supply that can adjust
an amount of current so as to adjust the Lorentz force is connected
with the pair of electrodes in the electrode device.
3. The device for continuously removing impurities from molten
metal according to claim 1, wherein the outlet-side closed end
plate is configured to be capable of adjusting a mounting position
in the molten metal flow path body in the longitudinal direction so
as to adjust a length of the impurity removal space.
4. The device for continuously removing impurities from molten
metal according to claim 1, wherein the outlet-side electrode is
provided in a floating state in the impurity removal space so that
a first gap opened vertically is formed between the outlet-side
electrode and a bottom surface of the molten metal flow path
forming body and a second gap opened in the longitudinal direction
is formed between the outlet-side electrode and the outlet-side
closed end plate.
5. The device for continuously removing impurities from molten
metal according to claim 1, wherein the outlet-side closed end
plate is configured such that a height of the outlet-side closed
end plate can be adjusted so that an amount of molten metal that
overflows can be adjusted.
6. The device for continuously removing impurities from molten
metal according to claim 1, wherein a molten metal supply device
that supplies molten metal to the molten metal flow path body and
can adjust a supply amount is provided in a preceding stage of the
molten metal flow path body.
7. A continuous impurity removal method for removing impurities
from molten metal in sending electrically conductive molten metal
to a metal product manufacturing device in a next stage, the method
comprising: preparing a molten metal flow path body having a molten
metal flow path for flowing electrically conductive molten metal
that has flown from outside toward the metal product manufacturing
device; providing an inlet-side closed end plate and an outlet-side
closed end plate in the molten metal flow path body so as to
partition a front and a rear of the molten metal flow path and form
an impurity removal space; providing, in the impurity removal
space, an electrode device composed of an inlet-side electrode and
an outlet-side electrode that face each other in a longitudinal
direction in which molten metal flows and can be put into
electrical contact with molten metal in the impurity removal space;
providing, outside the molten metal flow path forming body, a
magnetic field device composed of a pair of permanent magnets that
face each other in a width direction intersecting the longitudinal
direction, sandwich the impurity removal space of the molten metal
flow path forming body in the width direction, have opposite poles
facing each other, and can form a magnetic field in molten metal in
the impurity removal space; and causing an urging device composed
of the electrode device and the magnetic field device to apply a
Lorentz force downward to molten metal in the impurity removal
space so as to increase a density of the molten metal and cause
impurities in the molten metal to rise up to a surface of the
molten metal.
8. The method for continuously removing impurities from molten
metal according to claim 7, further comprising adjusting an amount
of current applied from a power supply to the pair of electrodes in
the electrode device so as to adjust the Lorentz force.
9. The method for continuously removing impurities from molten
metal according to claim 7, further comprising a step of adjusting
a mounting position of the outlet-side closed end plate in the
molten metal flow path body in the longitudinal direction so as to
adjust a length of the impurity removal space.
10. The method for continuously removing impurities from molten
metal according to claim 7, wherein the outlet-side electrode is
provided in a floating state in the impurity removal space so that
a first gap opened vertically is formed between the outlet-side
electrode and a bottom surface of the molten metal flow path
forming body and a second gap opened in the longitudinal direction
is formed between the outlet-side electrode and the outlet-side
closed end plate.
11. The method for continuously removing impurities from molten
metal according to claim 7, wherein the outlet-side closed end
plate is configured such that a height of the outlet-side closed
end plate can be adjusted and an amount of molten metal that
overflows can be adjusted.
12. The method for continuously removing impurities according to
claim 7, wherein a molten metal supply device provided in a
preceding stage of the molten metal flow path body adjusts an
amount of molten metal supplied to the molten metal flow path
body.
13. A device for continuously removing impurities from molten
metal, which sends electrically conductive molten metal to a metal
product manufacturing device in a next stage, the device
comprising: a molten metal flow path body having a molten metal
flow path for flowing electrically conductive molten metal that has
flown from outside toward the metal product manufacturing device;
an inlet-side closed end plate and an outlet-side closed end plate
that are provided in the molten metal flow path body so as to
partition a front and a rear of the molten metal flow path and form
an impurity removal space; an electrode device composed of an
inlet-side electrode and an outlet-side electrode that are provided
in the impurity removal space, face each other in a longitudinal
direction in which molten metal flows, and can be put into
electrical contact with molten metal in the impurity removal space;
and a magnetic field device composed of a pair of permanent magnets
that are provided outside the molten metal flow path forming body,
face each other in a width direction intersecting the longitudinal
direction, sandwich the impurity removal space of the molten metal
flow path forming body in the width direction, have opposite poles
facing each other, and can form a magnetic field in molten metal in
the impurity removal space, wherein the outlet-side electrode is
provided in a floating state in the impurity removal space so that
a first gap opened vertically is formed between the outlet-side
electrode and a bottom surface of the molten metal flow path
forming body and a second gap opened in the longitudinal direction
is formed between the outlet-side electrode and the outlet-side
closed end plate, and the electrode device and the magnetic field
device constitute an urging device that can apply a Lorentz force
downward to molten metal in the impurity removal space so as to
increase a density of the molten metal and cause impurities in the
molten metal to rise up to a surface of the molten metal, and can
send molten metal on an inner side than the outlet-side electrode
in the impurity removal space through the first gap to the second
gap.
14. A continuous impurity removal method for removing impurities
from molten metal in sending electrically conductive molten metal
to a metal product manufacturing device in a next stage, the method
comprising: preparing a molten metal flow path body having a molten
metal flow path for flowing electrically conductive molten metal
that has flown from outside toward the metal product manufacturing
device; providing an inlet-side closed end plate and an outlet-side
closed end plate in the molten metal flow path body so as to
partition a front and a rear of the molten metal flow path and form
an impurity removal space; providing, in the impurity removal
space, an electrode device composed of an inlet-side electrode and
an outlet-side electrode that face each other in a longitudinal
direction in which molten metal flows and can be put into
electrical contact with molten metal in the impurity removal space;
providing, outside the molten metal flow path forming body, a
magnetic field device composed of a pair of permanent magnets that
face each other in a width direction intersecting the longitudinal
direction, sandwich the impurity removal space of the molten metal
flow path forming body in the width direction, have opposite poles
facing each other, and can form a magnetic field in molten metal in
the impurity removal space; providing the outlet-side electrode in
a floating state in the impurity removal space so that a first gap
opened vertically is formed between the outlet-side electrode and a
bottom surface of the molten metal flow path forming body and a
second gap opened in the longitudinal direction is formed between
the outlet-side electrode and the outlet-side closed end plate; and
causing an urging device composed of the electrode device and the
magnetic field device to apply a Lorentz force downward to molten
metal in the impurity removal space so as to increase a density of
the molten metal and cause impurities in the molten metal to rise
up to a surface of the molten metal, and send molten metal on an
inner side than the outlet-side electrode through the first gap to
the second gap.
Description
TECHNICAL FIELD
[0001] The present invention relates to a device and a method for
continuously removing impurities from molten metal.
BACKGROUND ART
[0002] Conventionally, productization from molten metal having
electrical conductivity (conductivity), that is, non-ferrous molten
metal (e.g., Al, Cu, Zn, or Si, alloy including at least two of
these, Mg alloy, or the like) or molten metal other than
non-ferrous molten metal includes, for example, steps of dissolving
raw materials, adjusting components, removing impurities mixed in
molten metal, and molding. Removal of impurities is generally
referred to as purification of molten metal, and, for example, a
ceramic filter is used therefor.
[0003] However, since an impurity removal method using a filter is,
of course, a filtration method, clogging is likely to occur.
Therefore, there is a problem such that the workability is
deteriorated and the running cost is increased.
[0004] In other words, in a case of a filter type, how large the
mesh is set to is actually an important point. In order to remove
not only large impurities but also fine impurities, the mesh must
be fine. However, if the mesh is made fine, clogging is more likely
to occur. For example, clogging may occur instantaneously, and
production may stop.
[0005] Thus, conventionally, flux is previously introduced into the
molten metal prior to removal with a filter. By such introduction,
impurities are changed into substances having a large particle
size. As a result, it becomes possible to remove impurities while
keeping the mesh large to some extent, and it is possible to
increase the removal efficiency (trap efficiency) of the filter.
However, it is not preferable to introduce flux into the molten
metal in terms of product quality in many cases.
SUMMARY OF INVENTION
Technical Problem
[0006] As described above, according to a conventional method, it
is actually impossible to continuously produce products without
stopping production of products while removing impurities,
including fine impurities, from molten metal.
[0007] The present invention has been made in view of such
circumstances, and it is an object thereof to provide a device and
a method for continuously removing impurities for enabling
continuous manufacture of products while removing impurities from
non-ferrous metal or other molten metal containing impurities with
high accuracy.
Solution to Problem
[0008] An embodiment of the present invention is
[0009] a device for continuously removing impurities from molten
metal, which sends electrically conductive molten metal to a metal
product manufacturing device in a next stage, the device
including:
[0010] a molten metal flow path body having a molten metal flow
path for flowing electrically conductive molten metal that has
flown from outside toward the metal product manufacturing
device;
[0011] an inlet-side closed end plate and an outlet-side closed end
plate that are provided in the molten metal flow path body so as to
partition a front and a rear of the molten metal flow path and form
an impurity removal space;
[0012] an electrode device composed of an inlet-side electrode and
an outlet-side electrode that are provided in the impurity removal
space, face each other in a longitudinal direction in which molten
metal flows, and can be put into electrical contact with molten
metal in the impurity removal space; and
[0013] a magnetic field device composed of a pair of permanent
magnets that are provided outside the molten metal flow path
forming body, face each other in a width direction intersecting the
longitudinal direction, sandwich the impurity removal space of the
molten metal flow path forming body in the width direction, have
opposite poles facing each other, and can form a magnetic field in
molten metal in the impurity removal space,
[0014] in which the electrode device and the magnetic field device
constitute an urging device that can apply a Lorentz force downward
to molten metal in the impurity removal space so as to increase a
density of the molten metal and cause impurities in the molten
metal to rise up to a surface of the molten metal.
[0015] Furthermore, an embodiment of the present invention is
[0016] a continuous impurity removal method for removing impurities
from molten metal in sending electrically conductive molten metal
to a metal product manufacturing device in a next stage, the method
including:
[0017] preparing a molten metal flow path body having a molten
metal flow path for flowing electrically conductive molten metal
that has flown from outside toward the metal product manufacturing
device;
[0018] providing an inlet-side closed end plate and an outlet-side
closed end plate in the molten metal flow path body so as to
partition a front and a rear of the molten metal flow path and form
an impurity removal space;
[0019] providing, in the impurity removal space, an electrode
device composed of an inlet-side electrode and an outlet-side
electrode that face each other in a longitudinal direction in which
molten metal flows and can be put into electrical contact with
molten metal in the impurity removal space;
[0020] providing, outside the molten metal flow path forming body,
a magnetic field device composed of a pair of permanent magnets
that face each other in a width direction intersecting the
longitudinal direction, sandwich the impurity removal space of the
molten metal flow path forming body in the width direction, have
opposite poles facing each other, and can form a magnetic field in
molten metal in the impurity removal space; and
[0021] causing an urging device composed of the electrode device
and the magnetic field device to apply a Lorentz force downward to
molten metal in the impurity removal space so as to increase a
density of the molten metal and cause impurities in the molten
metal to rise up to a surface of the molten metal.
[0022] Furthermore, an embodiment of the present invention is
[0023] a device for continuously removing impurities from molten
metal, which sends electrically conductive molten metal to a metal
product manufacturing device in a next stage, the device
including:
[0024] a molten metal flow path body having a molten metal flow
path for flowing electrically conductive molten metal that has
flown from outside toward the metal product manufacturing
device;
[0025] an inlet-side closed end plate and an outlet-side closed end
plate that are provided in the molten metal flow path body so as to
partition a front and a rear of the molten metal flow path and form
an impurity removal space;
[0026] an electrode device composed of an inlet-side electrode and
an outlet-side electrode that are provided in the impurity removal
space, face each other in a longitudinal direction in which molten
metal flows, and can be put into electrical contact with molten
metal in the impurity removal space; and
[0027] a magnetic field device composed of a pair of permanent
magnets that are provided outside the molten metal flow path
forming body, face each other in a width direction intersecting the
longitudinal direction, sandwich the impurity removal space of the
molten metal flow path forming body in the width direction, have
opposite poles facing each other, and can form a magnetic field in
molten metal in the impurity removal space,
[0028] in which the outlet-side electrode is provided in a floating
state in the impurity removal space so that a first gap opened
vertically is formed between the outlet-side electrode and a bottom
surface of the molten metal flow path forming body and a second gap
opened in the longitudinal direction is formed between the
outlet-side electrode and the outlet-side closed end plate, and
[0029] the electrode device and the magnetic field device
constitute an urging device that can apply a Lorentz force downward
to molten metal in the impurity removal space so as to increase a
density of the molten metal and cause impurities in the molten
metal to rise up to a surface of the molten metal, and can send
molten metal on an inner side than the outlet-side electrode in the
impurity removal space through the first gap to the second gap.
[0030] Furthermore, an embodiment of the present invention is
[0031] a continuous impurity removal method for removing impurities
from molten metal in sending electrically conductive molten metal
to a metal product manufacturing device in a next stage, the method
including:
[0032] preparing a molten metal flow path body having a molten
metal flow path for flowing electrically conductive molten metal
that has flown from outside toward the metal product manufacturing
device;
[0033] providing an inlet-side closed end plate and an outlet-side
closed end plate in the molten metal flow path body so as to
partition a front and a rear of the molten metal flow path and form
an impurity removal space;
[0034] providing, in the impurity removal space, an electrode
device composed of an inlet-side electrode and an outlet-side
electrode that face each other in a longitudinal direction in which
molten metal flows and can be put into electrical contact with
molten metal in the impurity removal space;
[0035] providing, outside the molten metal flow path forming body,
a magnetic field device composed of a pair of permanent magnets
that face each other in a width direction intersecting the
longitudinal direction, sandwich the impurity removal space of the
molten metal flow path forming body in the width direction, have
opposite poles facing each other, and can form a magnetic field in
molten metal in the impurity removal space;
[0036] providing the outlet-side electrode in a floating state in
the impurity removal space so that a first gap opened vertically is
formed between the outlet-side electrode and a bottom surface of
the molten metal flow path forming body and a second gap opened in
the longitudinal direction is formed between the outlet-side
electrode and the outlet-side closed end plate; and
[0037] causing an urging device composed of the electrode device
and the magnetic field device to apply a Lorentz force downward to
molten metal in the impurity removal space so as to increase a
density of the molten metal and cause impurities in the molten
metal to rise up to a surface of the molten metal, and send molten
metal on an inner side than the outlet-side electrode through the
first gap to the second gap.
BRIEF DESCRIPTION OF DRAWINGS
[0038] FIG. 1 is an explanatory plan view illustrating the overall
configuration of a device for continuously removing impurities from
molten metal according to an embodiment of the present
invention.
[0039] FIG. 2 is an explanatory sectional view taken along line
II-II of FIG. 1.
[0040] FIG. 3 is an explanatory sectional view taken along line
III-III of FIG. 2.
[0041] FIG. 4 is an explanatory sectional view taken along line
IV-IV of FIG. 2.
[0042] FIG. 5 is an explanatory view illustrating a usage state
corresponding to a part of FIG. 2.
[0043] FIG. 6 is an explanatory view for explaining generation of a
Lorentz force.
[0044] FIG. 7a is an explanatory view for explaining a pressure
state in molten metal.
[0045] FIG. 7b is an explanatory view for explaining a pressure
state in molten metal.
[0046] FIG. 8 is an explanatory partial view illustrating a
modified example corresponding to FIG. 5.
[0047] FIG. 9a is an explanatory longitudinal sectional view
illustrating a specific example of an outlet-side closed end
plate.
[0048] FIG. 9b is an explanatory longitudinal sectional view
illustrating a specific example of an outlet-side closed end
plate.
DESCRIPTION OF EMBODIMENTS
[0049] Hereinafter, embodiments of the present invention will be
described with reference to the drawings.
[0050] FIG. 1 is an explanatory plan view illustrating the entire
configuration of an embodiment of a device 100 for continuously
removing impurities from molten metal according to the present
invention. The metal is a non-ferrous metal having electrical
conductivity or another metal. The non-ferrous metal or another
metal is a non-ferrous metal of a conductor (electric conductor)
such as Al, Cu, Zn, an alloy including at least two of these, or an
Mg alloy, or a metal other than the non-ferrous metal.
[0051] In FIG. 1, the flow of molten metal M is indicated by a
solid arrow AR1, and the movement of impurities IM is indicated by
a broken arrow AR2. That is, it is shown that the impurities IM are
removed laterally while the molten metal M is flowing along the
arrow AR1.
[0052] More specifically, FIG. 1 illustrates a case where a tilting
type melting furnace is used as an example. As can be seen from
FIG. 1, the impurity removing device 100 receives molten metal M
from a melting furnace 200 in the preceding stage, allows the
molten metal M flow inside the impurity removing device 100, causes
impurities in the molten metal M to positively rise up to the
vicinity of the liquid surface during the molten metal M is flowing
so that the impurities can be removed by arbitral means, and causes
the molten metal M to flow into a mold 300 in the following stage
after impurities are removed, so that a product (ingot) such as a
billet or a slab, for example, can be manufactured from
high-quality molten metal M. A general-purpose melting furnace 200
and a general-purpose mold 300 can be employed. Therefore, for
example, the impurity removing device 100 of the present invention
can be additionally provided to an existing melting furnace 200 and
an existing mold 300 later.
[0053] The melting furnace 200 is a general-purpose tilting type
melting furnace as described above. That is, the melting furnace
200 includes a container-shaped melting furnace main body 1 having
an opening 2 at the top. A spout 3 for the molten metal M is formed
at a side wall on the front side (left side in the figure) of the
tilting type melting furnace main body 1. A general-purpose gas
burner 4 is attached to a rear side wall. The raw material of the
electrically conductive metal introduced from the opening 2 is
heated by the gas burner 4 to be molten metal M and is housed in
the melting furnace main body 1.
[0054] FIG. 2 is an explanatory longitudinal sectional view taken
along line II-II of FIG. 1. As can be seen from FIG. 2, a hinge
mechanism 6 is provided at an outer bottom portion of the melting
furnace main body 1 so as to be able to derrick and rotate. As a
result, it is configured to be able to derrick and rotate on a
horizontal shaft 6a from an upright state to an inclined pouring
state. This melting furnace main body 1 can adjust the amount of
molten metal supplied to a gutter main body 10. The molten metal M
is poured from the spout 3 to the impurity removing device 100 in
the next stage by tilting the melting furnace main body 1. This
state is illustrated in FIG. 5. By adjusting the angle at which the
melting furnace main body 1 is inclined, the head h illustrated in
FIG. 2 is changed, and the flow rate of the molten metal M from the
melting furnace main body 1 to the gutter main body 10 can be
changed. It is to be noted that the level of the molten metal M in
the gutter main body 10 is performed by changing the height of an
outlet-side closed end plate 11. Moreover, as illustrated in FIG.
8, one electrode 13b, which will be described later, can be
provided separately from the inlet-side closed end plate 8. The
flow of the molten metal M at this time is as illustrated in FIG.
8.
[0055] The impurity removing device 100 that receives the molten
metal M from the melting furnace 200 is configured to have a
function as a so-called gutter that allows the received molten
metal M flow from right to left in FIG. 1 and give the molten metal
M to the mold 300 in the next stage, and a selective accumulation
function of selectively accumulating impurities in the molten metal
M that are caused to rise up to the vicinity of the liquid surface
during the flow.
[0056] That is, as can be seen particularly from FIG. 2, the
impurity removing device 100 includes the gutter main body (sorting
tank) (molten metal flow path body) 10, and a magnetic field device
12 that sandwiches the gutter main body 10 in the width direction.
Furthermore, as can be seen particularly from FIG. 1, the impurity
removing device 100 has an electrode device 13 composed of a pair
of electrodes 13a and 13b that are housed inside the gutter main
body 10 (molten metal flow path) and face each other. The magnetic
field device 12 and the electrode device 13 constitute an urging
device 30 that applies a Lorentz force f downward to the molten
metal M, as will be described later in detail.
[0057] As can be seen from FIG. 1, the gutter main body 10 is
configured to guide the molten metal M from the melting furnace 200
to the mold 300, and the gutter main body 10 is made of a
refractory material and has a substantially U-shaped cross section
as can be seen from FIG. 3. The gutter main body 10 can be
installed with a gradient so that the left side becomes lower than
the right side in FIG. 2 in order to make the flow of the molten
metal M smooth.
[0058] As can be seen from FIG. 2, the gutter main body 10 has an
inflow auxiliary plate 7A that receives the molten metal M from the
melting furnace 200, and an inlet-side closed end plate 8, a main
flow path bottom plate 9, and the outlet-side closed end plate 11
that follow. Furthermore, there are right and left side plates 15a
and 15b sandwiching these members in the width direction. The right
and left side plates 15a and 15b, the inlet-side closed end plate
8, and the outlet-side closed end plate 11 form a main flow path
(impurity removal space) 14 as an impurity removal portion.
[0059] The outlet-side closed end plate 11 can be configured such
that the height thereof can be adjusted. Arbitral configuration
configured such that the height thereof can be adjusted can be
employed. For example, as can be seen from FIGS. 9a and 9b, the
outlet-side closed end plate 11 may be composed of a main body 11a
and an auxiliary plate 11b which are bolted to each other, and the
auxiliary plate 11b may be vertically shifted with respect to the
main body 11a.
[0060] The inlet-side electrode 13a in the electrode device 13 is
provided in close contact with the inlet-side closed end plate 8,
and the outlet-side electrode 13b is spaced from the outlet-side
closed end plate 11 with a gap (second gap) G2 in the longitudinal
direction and is provided in a floating state of floating with a
gap (first gap) G1 in the depth direction. As a result, the molten
metal M flows through the gaps G1 and G2, flows over the
outlet-side closed end plate 11, or so-called overflows, and flows
out from the main flow path 8 through an outflow auxiliary plate 7B
toward the mold 300 as will be described later.
[0061] A power supply 16 is connected between the pair of
electrodes 13a and 13b in the electrode device 13. This power
supply 16 is configured to be able to pass an alternating current
as well as a direct current. Furthermore, it is configured to
switch the polarity of a direct current.
[0062] The magnetic field device 12 is provided on both right and
left sides of the gutter main body 10 as can be seen from FIGS. 1
and 4. This magnetic field device 12 includes a pair of right and
left permanent magnets 12a and 12b, and the gutter main body 10 is
sandwiched between the pair of permanent magnets 12a and 12b. The
pair of permanent magnets 12a and 12b have opposite poles facing
each other, and in this embodiment, the inner sides of the pair of
permanent magnets 12a and 12b are magnetized respectively to an S
pole and an N pole. As a result, the lines of magnetic force ML
from an upper permanent magnet 12b in FIG. 4 penetrate the molten
metal M in the gutter main body 10 and reach a lower permanent
magnet 12a. Thus, in actual use, a current I flows between the pair
of electrodes 13a and 13b as can be seen from FIG. 4. Therefore,
the lines of magnetic force ML and the current I intersect each
other. As a result, a Lorentz force f to push the molten metal M
downward is generated in the molten metal M as illustrated in FIG.
6. It is to be noted that the magnetic field device 12 can be
constituted of an electromagnet.
[0063] Next, the operation of the embodiment of the present
invention will be described.
[0064] As can be seen from FIGS. 1 and 2, when electrically
conductive metal is introduced into the melting furnace 200 and is
heated and molten, the molten metal M is caused to flow from the
melting furnace 200 into the main flow path 14 by increase of the
molten metal M and the tilt illustrated in FIG. 5.
[0065] In this main flow path 14, the lines of magnetic force ML
and the current I intersect each other as can be seen from FIG. 4.
This concept is illustrated in FIG. 6 described above. As a result,
a Lorentz force f is generated and acts on the molten metal M as a
force in a direction to push the molten metal M downward. As a
result, the pressure inside the molten metal M increases as it goes
from the surface to a bottom portion. The state of pressure
distribution in this case is illustrated in FIG. 7a. That is, the
density of the molten metal M becomes larger toward the bottom
portion due to the gravity in addition to the Lorentz force f. This
density affects greatly the buoyancy of impurities IM contained in
the molten metal M. That is, when the density is high, a large
buoyancy acts on impurities IM.
[0066] Therefore, in a state in which the Lorentz force f is
generated, impurities IM in the molten metal M rise in the molten
metal M and reach the liquid level. That is, impurities IM tend to
settle in the molten metal M by its own weight. Moreover, a
buoyancy due to the molten metal M acts on impurities IM. Thus,
when the density of the molten metal M increases, a large buoyancy
acts on impurities IM in the molten metal M. Therefore, impurities
IM rise or fall according to a difference between the buoyancy and
the settlement force. Thus, by setting the Lorentz force f to an
expected value, the buoyancy becomes larger than the settlement
force, and impurities IM rise in the molten metal M and reach the
vicinity of the liquid surface. This operation is continuously
performed in the process of flow of the molten metal M through the
main flow path 14.
[0067] In this way, impurities IM rise up to the vicinity of the
surface of the molten metal M. Impurities IM that have risen up are
automatically or artificially discharged to an impurity receiver 40
via the impurity removing plate 7C as can be seen from FIG. 3 by
arbitral means. As illustrated in FIG. 3, the impurity removing
plate 7C has a mountain-shaped cross section.
[0068] Moreover, in the gutter main body 10, the molten metal M is
pushed down by application of pressure as illustrated in FIG. 7b as
described above to decrease the liquid level. Along with this, the
molten metal M flows through the gap G1 and reaches the gap G2 as
can be seen from FIG. 2. As a result, a head h is generated, and a
pressure corresponding to the head h is applied to the molten metal
M in the gutter main body 10 as illustrated in FIG. 2. Here, since
impurities IM rise in the molten metal M and gather in the vicinity
of the liquid surface, the molten metal M flowing through the gap
G1 contains substantially no impurity IM. That is, molten metal M
substantially containing no impurity IM exists in the gap G2. Thus,
the liquid level of the molten metal M rises in the gap G2.
Therefore, the substantially purified molten metal M flows over the
outlet-side closed end plate 11 and flows into the mold 30 via the
outflow auxiliary plate 7B. As a result, a high-quality product
with less impurities IM can be obtained. In FIG. 2, h denotes a
head of two liquid levels.
[0069] The above-described fact that application of the Lorentz
force f can cause impurities IM in the molten metal M to rise in
the molten metal M will be described below in detail.
[0070] The magnetic field strength in the molten metal M in FIG. 4
will be denoted by B. Here, as can be seen from FIGS. 7a and 7b, it
is assumed that a Lorentz force f is generated downward. At this
time, a force F that acts on a bottom portion of the gutter main
body 10 is the sum of a force fg due to the gravity and a force fm
due to the Lorentz force f, and is expressed as the following
expression.
F=fg+fm
[0071] Here, since the horizontal area A of the gutter main body 10
is A=l.times.a (l: the length of the gutter main body 10, a: the
width of the gutter main body 10), the pressure P at a bottom
portion of the gutter main body 10 is expressed as the following
expression.
[0072] P=F/A Furthermore, assuming here that the current density
between the pair of electrodes 13a and 13b is constant, the Lorentz
force f becomes zero at the surface of the molten metal, and
I.times.B.times.l (N) at a bottom portion. Thus, the pressure is
highest at a bottom portion. This state is illustrated in FIGS. 7a
and 7b.
[0073] Furthermore, the apparent density of the molten metal M
affected by two influences of the Lorentz force f and the gravity
is denoted by .rho.m, the density of mixed impurity particles is
denoted by .rho.s, and the particle size is denoted by V. The
buoyancy fa received from the molten metal M and the force fg due
to the gravity simultaneously act on the impurity particles. At
this time, assuming that the force received by the impurity
particles is denoted by Fs, the following expression is
satisfied.
Fs = fa - fg = .rho. m .times. V - .rho. s .times. V = ( .rho. m -
.rho. s ) .times. V ##EQU00001##
Accordingly, the impurity particles move in the molten metal M as
follows.
[0074] (a) .rho.m-.rho.s>0 Rise
[0075] (b) .rho.m-.rho.s<0 Settlement
[0076] (c) .rho.m-.rho.s=0 Floating
[0077] With the embodiment of the present invention described
above, the following advantages can be obtained.
[0078] (1) Continuous purification of molten metal M is possible,
which is consistent with a continuous casting method that has
become a standard technology in the industry.
[0079] (2) Although the rise speed of impurities varies depending
on the particle size, density, and the like of impurities, the
residence time of the molten metal M in the gutter main body
(sorting tank) may be increased by slowing down the flow speed or
lengthening the gutter main body, for example, in the case of
separating objects (having small particle size) having a low rise
speed.
[0080] (3) Since the purification is neither physical nor
mechanical, there is no need to replace a filter, which not only
improves the work efficiency but also reduces costs.
[0081] (4) The specific gravity of the molten metal can be easily
changed by changing the magnetic field strength or the current
value, and an impurity removing operation can be performed
according to the type of the molten metal M to be subjected to
impurity removal.
* * * * *