Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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AGITATOR AND MELTING FURNACE WITH AGITATOR
BACKGROUND OF THE INVENTION
= 10 Held of the Invention
The present invention relates to an agitator and a melting
furnace with an agitator.
Background Art
Conventionally, among melting furnaces for melting, for
example, aluminum for the purpose of recycling, aluminum
melting furnaces with agitators can be classified into those of a
mechanical type, which insert a rotational body into a furnace in
order to directly agitate aluminum, those of a low-pressure type,
which use a negative pressure pump to suck up melt to agitate
it, and those of an electromagnetic type which generate a
shifting magnetic field by causing a three-phase alternating
current to flow through a fixed electrode and
electromagnetically agitate aluminum based on the generated
magnetic field..
The aforementioned mechanical-type furnaces do not
have a sufficient durability since the rotational body is used to
directly agitate a high-temperature melt. Furthermore, there is
a problem in that the operation and the maintenance thereof
are complicated. Low-pressure type furnaces are not widely
used since the operability thereof is not so good.
Electromagnetic-type furnaces require a high current, thereby
increasing power consumption, resulting in high running costs.
Furthermore, since the cooling of coils thereof requires great
care, the cost of the entire equipment is inevitably increased,
which hinders the widespread use thereof.
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SUMMARY OF THE INVENTION
The present invention is proposed in consideration of the
aforementioned current situation, and it is an object of the
present invention to propose an agitator and a melting furnace
which are not expensive, have good operability, can operate
with a low running cost, and can surely melt an inputted
material.
A melting furnace with agitator according to a first aspect
of the present invention includes:
a melting furnace main body for melting a row material
to make a melt; and
an agitator for applying an alternating field to the melt in
the melting furnace main body to agitate the melt,
the agitator including a plurality of magnets which are
arranged so that magnetic lines of force emitted from one of the
magnets pass through the melt in the melting furnace main
body and return to another magnet, the magnets being fixed to
an inclined surface which is inclined by an angle with respect to
a horizontal surface, and being rotatable around an axis
substantially perpendicular to the inclined surface.
An agitator for applying an alternating field to a melt in a
melting furnace main body according to a second aspect of the
present invention includes a plurality of magnets, which are
arranged so that magnetic lines of force emitted from one of the
magnets pass through the melt in the melting furnace main
body and return to another magnet, the magnets being fixed to
an inclined surface which is inclined by an angle with respect to
a horizontal surface, and being rotatable around an axis
substantially perpendicular to the inclined surface. . .
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The present invention, in another aspect, relates to a melting furnace
with agitator comprising: a melting furnace main body for melting a raw
material to
make a melt; and an agitator for applying an alternating field to the melt in
the melting
furnace main body to agitate the melt, the agitator including a plurality of
permanent
magnets, each of the magnets having magnetic poles on an upper portion and a
lower portion thereof, and wherein said magnets are arranged so that magnetic
lines
of force emitted from one of the permanent magnets pass through the melt in
the
melting furnace main body and return to another magnet, the magnets being
fixed to
the inclined surface of a rotatable turntable which is inclined by an angle
with respect
to a horizontal surface, and being rotatable in one plane around an axis
substantially
perpendicular to the inclined surface; and wherein the magnetic poles of the
upper
portions of two permanent magnets adjacent to each other in a circumferential
direction on the turntable differ from each other, said agitator provided to a
support
base located below the melting furnace main body and wherein the angle of the
support base, and the agitator with a bottom surface of the melting furnace
main body
is adjustable by lifting up or pulling down one side of the support base and
rotating
around a substantially horizontal axis.
The present invention, in another aspect, relates to an agitator for
applying an alternating field to a melt in a melting furnace main body
comprising a
plurality of permanent magnets, each of the permanent magnets having magnetic
poles on an upper portion and a lower portion thereof, said magnets arranged
so that
magnetic lines of force emitted from one of the permanent magnets pass trough
the
melt in the melting furnace main body and return to another permanent magnet,
the
magnets being fixed to the inclined surface of a rotatable turntable which is
inclined
by an angle with respect to a horizontal surface, and being rotatable in one
plane
around an axis substantially perpendicular to the inclined surface; and
wherein the
magnetic poles of the upper portions of two permanent magnets adjacent to each
other in a circumferential direction on the turntable differ from each other,
said
agitator further comprising a support base, the agitator being provided to the
support
base wherein the angle of the support base, and the agitator, with the
horizontal
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surface is adjustable by lifting up or pulling down one side of the support
base and
rotating around a substantially horizontal axis.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1(a) is a vertically sectioned explanatory drawing of an embodiment
of the present invention, and Figs. 1(b) and 1(c) are enlarged views of a part
thereof.
Fig. 2 is a vertically sectioned explanatory drawing
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showing the operation state of Fig. 1.
Figs. 3(a) and 3(b) are a plan view and a side view,
respectively, showing an example of an arrangement of the
permanent magnets shown in Fig. 1.
Fig. 4 is a plan view showing another example of an
arrangement of the permanent magnets.
Fig. 5 is a vertically sectioned explanatory drawing
showing another embodiment of the present invention.
Figs. 6(a) and 6(b) are a plan view and a vertically
sectioned explanatory drawing, respectively, of an embodiment
of a furnace to which the apparatus of Fig. 1 is applied.
DESCRIPTION OF THE EMBODIMENTS
Fig. 1(a) shows an embodiment of the present invention
in a non-use state, and Fig. 2 shows it in a use sate. Figs. 1(b)
and 1(c) are drawings obtained by enlarging a part of Fig. 1(a).
Fig. 1(b) is a plan view viewing part of the apparatus of Fig.
1(a) from above, and Fig. 1(c) is a view viewing the part from
the same direction as Fig. 1(a). In Fig. 1(a), a frame 2 is fixed
on a floor 1. A magnetic field generating portion 3 is mounted
on the frame 2 in such a manner that it is rotatable around a
hinge 4, i.e., around a substantially horizontal axis extending in
a direction perpendicular to the surface of the drawing paper, so
as to be capable of moving up and down. That is to say, the
magnetic field generating portion 3 has a hollow housing
(support base) 6, which is mounted on the frame 2 so as to be
capable of rotating to move up and down around the hinge 4,
i.e., around a substantially horizontal axis, as can be
understood from Fig. 1(a) and Fig. 2. Actually, the moving up
and down operations are performed around the substantially
horizontal axis of the hinge 4 by lifting up the left side of the
housing 6 shown in Fig. 1 so as to move it away from a support
member 2A of the frame 2, and pulling it down to the original
position. Various kinds of mechanisms can be employed to
perform such an operation. In the shown embodiment, a screw
mechanism is employed. Of course, a gear mechanism can
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also be employed. In Fig. 1(a), a driving rod 9 is supported by
a support portion 8 fixed to the frame 2 so as to be capable of
rotating around an axis (substantially vertical axis) thereof. In
particular, as can be understood from Fig. 1(c), a handle (wheel
type handle) for driving rotation 9A is fixed to a substantially
central portion in the longitudinal direction of the driving rod 9.
The upper portion of the driving rod 9 is threaded to form a
so-called male screw portion 9B. The male screw portion 9B is
screwed into a substantially ball-shaped female screw body 9C.
Due to the rotations of the male screw portion 9B, the female
screw body 9C is moved up and down. In particular, as can be
understood from Fig. 1(b), members to be driven 10, 10 fixed to
the housing 6 are supported by the female screw body 9C in a
mutually rotatable manner by lateral axes 9D, 9D.
Furthermore, as can be understood from Fig. 1(c), slits 10A,
10A are formed in the members to be driven 10, 10 in a
longitudinal direction, so that they are mutually slidable with
respect to the axes 9D, 9D. With such a structure, when the
driving rod 9 is rotated with the handle 9A, the female screw
body 9C is moved up and down, thereby moving the members
to be driven 10, 10 so that the members to be driven 10, 10 are
rotated around the axes 9D, 9D and the axes 9D, 9D are slid
inside the slits 10A, 10A, resulting in that the magnetic field
generating portion 3 is lifted up, as shown in, for example, Fig.
2. That is to say, the housing 6 is rotated around the hinge 4
so as to move up and down. It is possible to control the degree
of movement of the housing 6 by adjusting the degree of
rotation of the handle 9A. The mechanism for moving the
housing 6 up and down is not limited to the aforementioned
one.
A magnetic field generating device (agitator) 12 is
provided within the housing 6. The magnetic field generating
device (agitator) 12 has a mounting base 13 fixed on the inner
bottom of the housing 6. A driving motor 14, the rotation
speed of which can be continuously changed, is fixed to the
mounting base 13. An axis of the driving motor 14 is
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connected to an axis 17A of a magnet base (turntable) 17 via a
coupling 15. The axis 17A is supported by a bearing 20 located
at a central portion of a stay 19, both ends of which are fixed to
the inner walls of the housing 6. As
can be particularly
5 understood from Figs. 3(a) and 3(b), rod-shaped permanent
magnets 22, 22 ... are fixed on the magnet base 17. Each
permanent magnet 22 has magnetic poles on both upper and
lower surfaces. The permanent magnets 22, 22 ... are arranged
in a manner that the magnetic poles of the upper surfaces of
two adjacent permanent magnets differ from each other. The
two adjacent permanent magnets form a magnet pair. In this
case, two magnet pairs are provided. As shown in Fig. 4, the
permanent magnets 22, 22 ... can be arranged so that four
magnet pairs are provided.
With such a structure, the
rotations of the driving motor 14 are conveyed to the magnet
pairs, i.e., the permanent magnets 22, 22 ... via the coupling 15
and the magnet base 17.
A melting furnace (melting furnace main body) 25 of a
non-magnetic material is provided above the housing 6
(magnetic field generating portion 3) and fixed by a mechanism
not shown. As can be understood from Fig. 1(a), a bottom
portion 25A of the melting furnace 25 is inclined by an angle 0.
In this manner, as can be understood from Fig. 2, the bottom
portion 25A contacts the upper surface of the housing 6 when
the housing 6 (magnetic field generating portion 3) is lifted
around the hinge 4 so that the magnetic lines of force can be
used as effectively as possible.
In order to use the apparatus shown in Figs. 1(a) to 2,
the housing 6 (magnetic field generating portion 3) in the state
of Fig. 1(a) is lifted around the hinge 4 to be brought into the
state of Fig. 2. In the state of Fig. 2, the magnetic lines of
force of each of the permanent magnets 22, 22 ... pass through
the melt 30, e.g., melted aluminum, as shown in Fig. 2.
In the state of Fig. 2, initially, aluminum in the melting
furnace 25 is melted by a burner or the like, not shown, to
make the melt 30. When aluminum scrap is put into the melt
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in this state and the permanent magnets 22, 22 ... are rotated
by the motor 14, the magnetic lines of force emitted from the
permanent magnets 22, 22 ... move to pass through the melt 30.
That is to say, an alternating field is applied to the melt 30.
Accordingly, an eddy current is generated, and the melt 30
starts being rotated around an axis substantially perpendicular
to the magnet base 17, i.e., in an inclined state in the melting
furnace 25. That is to say, the surface of the melt 30 is rotated
in a state substantially parallel to the surface of the magnet
base 17 (the upper surface of the lifted permanent magnets 22).
Thus, in this apparatus, the permanent magnet 22 is rotated in
a state of being inclined by an angle 0, as described above. In
a case where it is held in a horizontal state (8=0 ), the melt 30
is rotated with its central portion being concaved. In such a
case, the melt 30 is rotated to create an undisturbed flow. In
this state, it is not possible to melt aluminum with great
efficiency. In contrast, in this embodiment, the permanent
magnets 22 are included by an angle 0. Accordingly, as shown
in Fig. 2, the melt 30 is rotated in a state where the liquid
surface thereof is inclined by the magnetic lines of force.
Therefore, the flow of the melt 30 becomes irregular and
vigorous. Because of such a flow, when a row material
(aluminum scrap etc.) is put into the melt 30, the row material
does not float on the melt 30, but is efficiently mixed into the
melt 30, thereby surely being melted in a short time.
In order to effectively perform such an agitation
operation, it is desirable that the strength of the permanent
magnets 22 be set so that the magnetic field strength at the
inner bottom portion of the melting furnace 25 is 0.2 - 0.3T or
more. Furthermore, it is desirable that the rotation speed of
the permanent magnets 22 (magnet pairs), i.e., the magnet
base 17, be 60 - 250 rpm when there are two magnet pairs of
permanent magnets 22, as shown in Fig. 3. That is to say, the
rotation speed should be changed in accordance with the
number of permanent magnets 22, 22 ... provided on the
magnet base 17, i.e., the number of two adjacent permanent
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magnets 22, 22 (magnet pairs) having different magnetic poles.
It is desirable that when there are two magnet pairs as shown in
Fig. 3, the rotation speed should be about 60 - 250 rpm; when
there are four pairs as shown in Fig. 4, the rotation speed
should be about 30 - 125 rpm; and when there are eight pairs,
the rotation speed should be about 15 - 62.5 rpm. That is to
say, it is desirable that when there are n magnet pairs, the
rotation speed should be about (120/n) - (500/n) rpm. The
meaning of the rotation speed is as follows. A cycle of 1 Hz is
defined as a cycle in which only one pair of magnets passes a
reference point in one second due to the rotations of the
magnet base 17. It is desirable that the magnet base 17 be
rotated with the rotation speed to set the cycle to about 2 -
8.33 Hz.
The bottom surface of the melting furnace 25 should not
necessarily be inclined by an angle 0. The melting can be
performed with an angle of less than 0, or when 0 = 0, meaning
that the bottom surface is horizontal as can be understood from
Fig. 5.
Figs. 6 (a) and 6(b) show an embodiment in which the
apparatus shown in Figs. 1(a) to 2 is used as an auxiliary
furnace 41, and the melt obtained therein is poured into a large
scale furnace 42. That is to say, the melt 43 melted in the
auxiliary furnace 41 flows into the large scale furnace 42
provided above a frame 46 through a gap 44 of a partition 45
provided between the auxiliary furnace 41 and the large scale
furnace 42. In Fig. 6, the elements which are the same as
those used in Figs. 1 and 2 are assigned the same reference
numerals.
Thus, according to the present invention, it is possible to
effectively rotate the melt in the melting furnace, thereby
reliably melting the material to be put into the melt.
Additional advantages and modifications will readily occur
to those skilled in the art.
Therefore, the invention in its
broader aspects is not limited to the specific details and
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representative embodiments shown and described herein.
Accordingly, various modifications may be made without
departing from the scope of the general inventive
concepts as defined by the appended claims and their
equivalents.
