SPECIFICATION
TITLE OF INVENTION
TRANSVERSE FLUX INDUCTION HEATING DEVICE
5 Field of the Invention
[0001]
The present invention relates to a transverse flux induction heating device. In
particular, the transverse flux induction heating device is suitably used to inductively
heat a conductive sheet by making an alternating magnetic field 'approximately
10 perpendicularly intersect the conductive sheet.
Priority is claimed on Japanese Patent Application No. 2010-35198, filed on
February 19, 2010, the content of which is incorporated herein by reference.
Description of Related Art
15 [0002]
In the past, heating a conductive sheet such as a steel sheet, using an induction
heating device has been performed. The induction heating device generates Joule heat
based on an eddy current which is induced in the conductive sheet by an alternating
magnetic field (an alternating-current magnetic field) generated from a coil, in the
20 conductive sheet, and heats the conductive sheet by the Joule heat. A transverse flux
induction heating device is one type of such an induction heating device. The
transverse flux induction heating device heats a conductive sheet of a heating target by
making an alternating magnetic field approximately perpendicularly intersect the
conductive sheet.
25 [0003]
2
In the case of using such a transverse flux induction heating device, unlike the
case of using a solenoid-type induction heating device, there is a problem in that both
ends (both side ends) in the width direction of the conductive sheet of the heating target
become overheated.
5 The techniques described in Patent Citation 1 and Patent Citation 2 are
techniques related to such a problem.
In the technique described in Patent Citation 1, a movable plain shielding plate
made of a nonmagnetic metal is provided between a coil and each of both side ends of a
conductive sheet of a heating target.
10 Further, in the technique described in Patent Citation 2, a rhombic coil and an
oval coil which have different heating patterns are disposed along the conveyance
direction of a conductive sheet of a heating target, thereby heating the conductive sheet in
a desired heating pattern with respect to the width direction of the conductive sheet.
15 Patent Citation
[0004]
[Patent Citation 1] Japanese Unexamined Patent Application, First Publication
No. 562-35490
[Patent Citation 2] Japanese Unexamined Patent Application, First Publication
20 No. 2003-133037
SUMMARY OF THE INVENTION
Problems to be Solved by the Invention
[0005]
25 However, by only providing a simple plate-shaped shielding plate between the
3
coil and each of both side ends of the conductive sheet of the heating target, as in the
technique described in Patent Citation 1, since the eddy current spreads in an area
slightly to the inside of both side ends of the conductive sheet, eddy current density is
small, and since eddy currents flowing in both side ends of the conductive sheet cannot
5 flow out of the conductive sheet, eddy current density becomes large at both side ends.
Therefore, it is difficult to lower the temperatures of both side ends of the conductive
sheet and the smoothness of the temperature distribution in the width direction of the
conductive sheet is also significantly lowered (in particular, the slope of the temperature
distribution at each of both side ends of the conductive sheet becomes large).
10 Further, in the technique described in Patent Citation 2, it is possible to suppress
lowering of the smoothness of the temperature distribution in the width direction of a
specific conductive sheet. However, if the sheet width of the conductive sheet is
changed, the coil has to be reset depending on the sheet width. Therefore, a mechanism
for moving the coil is required and it is difficult to easily and quickly respond to a change
15 in sheet width.
In addition, in the techniques described in Patent Citation 1 and Patent Citation 2,
if the conductive sheet moves in a meandering manner, the smoothness of the
temperature distribution in the width direction of the conductive sheet is lowered.
[0006]
20 The present invention has been made in view of such problems and has an object
of providing a transverse flux induction heating device which allows unevenness of a
temperature distribution in the width direction of a conductive sheet of a heating target to
be reduced and allows variations in temperature distribution in the width direction of the
conductive sheet of the heating target due to meandering of the conductive sheet to be
25 reduced.
4
Methods for Solving the Problem
[0007]
(1) A transverse flux induction heating device according to an aspect of the
5 present invention allows an alternating magnetic field to intersect the sheet face of a
conductive sheet which is conveyed in one direction, thereby inductively heating the
conductive sheet. The transverse flux induction heating device includes: a heating coil
disposed such that a coil face faces the sheet face of the conductive sheet; a core around
which the heating coil is coiled; a shielding plate formed of a conductor and disposed
10 between the core and a side end portion in a direction perpendicular to the conveyance
direction of the conductive sheet; and a non-conductive soft magnetic material which is
attached to the shielding plate, wherein the shielding plate is interposed between the core
and the non-conductive soft magnetic material.
(2) The transverse flux induction heating device according to the above (1) may
15 further include a heat-resistant plate which is attached to the non-conductive soft
magnetic material, wherein the heat-resistant plate is disposed closer to the conductive
sheet than the non-conductive soft magnetic material.
(3) In the transverse flux induction heating device according to the above (1),
the shielding plate may have a cross section parallel to the coil face, and the cross section
20 may include the non-conductive soft magnetic material.
(4) In the transverse flux induction heating device according to the above (1), a
depressed portion which faces the side end portion in the direction perpendicular to the
conveyance direction of the conductive sheet may be formed in the surface facing the
conductive sheet of the shielding plate and the non-conductive soft magnetic material
25 may be housed in the depressed portion.
5
(5) In the transverse flux induction heating device according to the above (4), a
portion which is tapered off toward a side close to a central portion in a direction
perpendicular to the conveyance direction of the conductive sheet from a side away from
the central portion in the direction perpendicular to the conveyance direction of the
5 conductive sheet may be included in the depressed portion.
(6) In the transverse flux induction heating device according to the above (4), a
first portion which is tapered off toward the downstream side from the upstream side in
the conveyance direction of the conductive sheet and a second portion which is tapered
off toward the upstream side from the downstream side in the conveyance direction of
10 the conductive sheet may be included in the depressed portion, and the first portion and
the second portion may face each other in the conveyance direction of the conductive
sheet.
(7) In the transverse flux induction heating device according to the above (4),
the first portion may be rounded toward the downstream side and the second portion may
15 be rounded toward the upstream side.
Effects of the Invention
[0008]
According to the present invention, the non-conductive soft magnetic material is
20 mounted on the shielding plate which is disposed between the core around which the coil
is coiled and an end portion in the width direction of the conductive sheet. Through the
non-conductive soft magnetic material, the magnitude of an eddy current in the shielding
plate, which flows in the vicinity of the non-conductive soft magnetic material, can be
made large. Therefore, unevenness of the temperature distribution in the width
25 direction of the conductive sheet of a heating target can be reduced and variations in the
6
temperature distribution in the width direction of the conductive sheet of the heating
target due to meandering of the conductive sheet can be reduced.
BRIEF DESCRIPTION OF THE DRAWINGS
5 [0009]
FIG. 1 is a side view showing one example of the schematic configuration of a
continuous annealing line for a steel sheet according to an embodiment of the present
invention.
FIG 2A is a vertical cross-sectional view showing one example of the
10 configuration of an induction heating device according to this embodiment.
FIG. 2B is a vertical cross-sectional view showing one example of the
configuration of the induction heating device according to this embodiment.
FIG. 2C is a fragmentary perspective view showing one example of the
configuration of the induction heating device according to this embodiment.
15 FIG. 3 is a diagram showing one example of the configurations of an upper side
heating coil and a lower side heating coil according to this embodiment.
FIG. 4A is a top view showing one example of the configuration of a shielding
plate according to this embodiment.
FIG. 4B is a vertical cross-sectional view showing one example of the
20 configuration of the shielding plate according to this embodiment.
FIG 4C is a vertical cross -sectional view showing one example of the
configuration of the shielding plate according to this embodiment.
FIG. 4D is a fragmentary view when an area including a shielding plate 31 d
according to this embodiment is viewed from directly above a steel strip 10.
25 FIG. 4E is a transverse cross -sectional view showing one example of the
7
configuration of the shielding plate according to this embodiment.
FIG. S is a diagram showing one example of the relationship between the
amount of insertion of the shielding plate and a width temperature deviation ratio in an
example using this embodiment.
5 FIG. 6A is a top view showing one example of the configuration of a shielding
plate according to the first modified example of this embodiment.
FIG. 6B is a top view showing one example of the configuration of a shielding
plate according to the second modified example of this embodiment.
FIG. 6C is a vertical cross -sectional view showing one example of the
10 configuration of a shielding plate according to the third modified example of this
embodiment.
FIG. 7A is a vertical cross-sectional view showing one example of the
configuration of a shielding plate according to the fourth modified example of this
embodiment.
15 FIG. 7B is a vertical cross-sectional view showing one example of the
configuration of a shielding plate according to the fifth modified example of this
embodiment.
FIG. 7C is a vertical cross-sectional view showing one example of the
configuration of a shielding plate according to the sixth modified example of this
20 embodiment.
FIG 8A is a perspective view showing one example of the configuration of a
shielding plate according to the seventh modified example of this embodiment.
FIG. 813 is a perspective view showing one example of the configuration of a
shielding plate according to the eighth modified example of this embodiment.
25 FIG. 8C is a perspective view showing one example of the configuration of a
8
shielding plate according to the ninth modified example of this embodiment.
DETAILED DESCRIPTION OF THE INVENTION
[0010]
5 Hereinafter, an embodiment of the present invention will be described referring
to the drawings. In this embodiment, a case where a transverse flux induction heating
device is applied to a continuous annealing line for a steel sheet is described as an
example. In addition, in the following description, the "transverse flux induction
heating device" is referred to as an "induction heating device" for brevity, as necessary.
10 [Configuration of Continuous Annealing Line]
FIG. 1 is a side view showing one example of the schematic configuration of a
continuous annealing line for a steel sheet. In addition, in each drawing, for
convenience of explanation, only the necessary configuration is simplified and shown.
In FIG 1, a continuous annealing line 1 includes a first container 11, a second
15 container 12, a third container 13, a first sealing roller assembly 14, a conveyance unit 15,
a second sealing roller assembly 16, a gas supply unit 17, an alternating-current power
supply unit 18, rollers I9a to 19u (19), and an induction heating device 20.
[0011]
The first sealing roller assembly 14 transports a steel strip (a strip-shaped sheet,
20 a conductive sheet) 10 into the first container I1 while shielding the first container 11
from the external air. The steel strip 10 conveyed into the first container 11 by the first
sealing roller assembly 14 is conveyed into the second container 12 by the rollers 19a
and 19b in the first container 11. The steel strip 10 conveyed into the second container
12 is conveyed into the first container 11 again by the rollers 19g and 19h while being
25 heated by the induction heating device 20 disposed above and below the horizontal
9
portion of the second container 12 (the steel strip 10 which is conveyed). Here, the
induction heating device 20 is electrically connected to the alternating-current power
supply unit 18 and receives alternating-current power from the alternating-current power
supply unit 18, thereby generating an alternating magnetic field which intersects
5 approximately perpendicularly to the sheet face of the steel strip 10, and inductively
heating the steel strip 10. In addition, the details of the configuration of the induction
heating device 20 will be described later. Further, in the following explanation,
"electrical connection" is referred to as "connection" for brevity, as necessary.
[0012]
10 The steel strip 10 returned into the first container 11 is conveyed to the
conveyance unit 15 by way of a soaking and slow cooling stage by the rollers 19c to 19f.
The steel strip 10 conveyed to the conveyance unit 15 is conveyed into the third
container 13 by the rollers 19i and 19j. The steel strip 10 conveyed into the third
container 13 is conveyed while being moving in a vertically up and down manner by the
15 rollers 19k to 19u and rapidly cooled in the third container 13.
The second sealing roller assembly 16 sends the steel strip 10 rapidly cooled in
this way to a post-process while blocking the third container 13 from external air.
Into "the first container It, the second container 12, the third container 13, and
the conveyance unit 15" which become a "transport pathway of the steel strip 10" as
20 described above, nOn-oxidizing gas is supplied by the gas supply unit 17. Then, by "the
first sealing'roller assembly 14 and the second sealing roller assembly 16" which block
the inside (the inside of the continuous annealing line 1) from the outside (external air), a
non-oxidizing gaseous atmosphere is maintained in the first container 11, the second
container 12, the third container 13, and the conveyance unit 15.
25 . [0013]
10
[Configuration of Induction Heating Device]
FIGS. 2A to 2C are diagrams showing one example of the configuration of the
induction heating device.
Specifically, FIG. 2A is a diagram showing one example of the induction heating
5 device 20 in this embodiment, as viewed from a side of the continuous annealing line,
and is a vertical cross-sectional view cut (in the up-and-down direction in FIG. 1) along
the longitudinal direction of the steel strip 10. In FIG 2A, the steel strip 10 is conveyed
in the left direction (refer to an arrow pointing from the right to the left in FIG. 2A).
Further, FIG 2B is a vertical cross-sectional view showing one example of the induction
10 heating device 20 in this embodiment, as viewed in a direction ofA-A' in FIG I (that is,
a diagram as viewed from the downstream in a sheet conveyance direction). In FIG. 2B,
the steel strip 10 is conveyed in a direction from the back of the drawing to the front.
Further, FIG. 2C is a fragmentary perspective view partially showing one example of the
induction heating device 20 in this embodiment. In FIG, 2C, a lower right area shown
15 in FIG 2B is looked down from above the steel strip 10.
[0014]
In FIGS. 2A to 2C, the induction heating device 20 includes an upper side
inductor 21 and a lower side inductor 22.
The upper side inductor 21 includes a core 23, an upper side heating coil (a
20 heating coil) 24, and shielding plates 3la and 31c.
The upper side heating coil 24 is a conductor coiled around the core 23 through
a slot of the core 23 (here, a depressed portion of the core 23) and is a coil (a so-called
single turn) in which the number of turns is "1". Further, as shown in FIG 2A, the
upper side heating coil 24 has a portion, the vertical cross-sectional shape of which is a
25 hollow rectangle. A water-cooling pipe is connected to the end face of a hollow portion
11
of the hollow rectangle. Cooling water which is supplied from the water-cooling pipe
flows in the hollow portion (the inside of the upper side heating coil 24) of the hollow
rectangle, so that the upper side inductor 21 is cooled. Further, the shielding plates 31a
and 31c are mounted on the bottom surface (the slot side) of the core 23.
5 In addition, in FIG 2A, a length II in the upper side inductor 21 is 45 [mm], a
length 12 is 180 [mm], a length 13 is 80 [mm], a length 14 is 180 [mm], a length 15 is 45
[mm], a length 16 is 45 [mm], and a length 17 is 45 [mm]. Further, a width W of the steel
strip 10 is 900 [mm] and a thickness d, is 0.3 [mm]. However, these dimensions are not
limited to the values described above.
10 [0015]
The lower side inductor 22 includes a core 27, a lower side heating coil (a
heating coil) 28, and shielding plates 3lb and 31d, similarly to the upper side inductor
21.
The lower side heating coil 28 is also a conductor coiled around the core 27
15 through a slot of the core 27 and is a coil (a so-called single turn) in which the number of
turns is "1", similarly to the upper side heating coil 24. Further, the lower side heating
coil 28 has a portion, the vertical cross-sectional shape of which is a hollow rectangle,
similarly to the upper side heating coil 24. A water-cooling pipe is connected to the end
` face of a hollow portion of the hollow rectangle and can flow cooling water into the
20 hollow portion of the hollow rectangle.
[0016]
Further, a coil face (a face in which a loop is formed; a face in which a line of
magnetic force penetrates) of the upper side heating coil 24 of the upper side inductor 21
and a coil face of the lower side heating coil 28 of the lower side inductor 22 face each
25 other with the steel strip 10 interposed therebetween. In addition, the plate faces of the
12
shielding plates 31a to 31 d (31) face side end portions (edges) in the sheet width
direction of the steel strip 10. In order to satisfy such a positional relationship, the
upper side inductor 21 is provided further on the upper side (in the vicinity of the upper
surface of the horizontal portion of the second container 12) than the steel strip 10 and
5 the lower side inductor 22 is provided further on the lower side (in the vicinity of the
lower surface of the horizontal portion of the second container 12) than the steel strip 10.
As described above, the upper side inductor 21 and the lower side inductor 22
are different in the position to be disposed, but have the same configuration.
Further, in this embodiment, the shielding plates 3la to 31d can be individually
10 moved in the width direction (a direction of a double-headed arrow shown in FIG. 2B) of
the steel strip 10 based on an operation of a driving device (not shown).
[0017]
Further, in this embodiment, a distance d between the upper side heating coil 24
and the lower side heating coil 28, the heating coil widths 12 and 14 in the upper side
15 heating coil 24, and the heating coil widths 12 and 14 in the lower side heating coil 28 are
the same. Further, a position where an "overlap length R in the width direction of the
steel strip 10" between each of both side end portions of the steel strip 10 and each of the
shielding plates 31 a to 31 d is 90 [mm] is defined as the reference position.
Here, the heating coil width is the length in the width direction of the upper side
20 heating coil 24 (the lower side heating coil 28) that is in the slot. In the example shown
in FIG 2A, the heating coil width is equal to the length in the width direction of each of
the copper pipes 41a to 41 d shown in FIG 3, which will be described later, and is
approximately the same length as the width of the slot of each of the cores 23 and 27.
In addition, in the following explanation, each of the heating coil width of the
25 upper side heating coil 24 and the heating coil width of the lower side heating coil 28 is
13
simply referred to as a heating coil width, as necessary, and the distance between the
upper side heating coil 24 and the lower side heating coil 28 is referred to as a gap, as
necessary.
[0018]
5 [Configuration of Heating Coil]
FIG. 3 is a diagram showing one example of the configurations of the upper side
heating coil 24 and the lower side heating coil 28. In addition, an arrow shown in FIG
3 represents one example of a direction in which an electric current flows at. a certain
time.
10 As shown in FIG. 3, the upper side heating coil 24 has the copper pipes 41 a and
41b, and a copper bus bar (a connection plate) 42b which is connected to the base end
sides of the copper pipes 41a and 41b. Further, the lower side heating coil 28 has the
copper pipes 41c and 41d, and a copper bus bar 42f which is connected to the base end
sides of the copper pipes 41 c and 41 d.
15 [0019]
One end (the front end side of the copper pipe 41a) of the upper side heating coil
24 and an output terminal on one side of the alternating-current power supply unit 18 are
mutually connected through a copper bus bar 42a. On the other hand, the other end (the
front end side of the copper pipe 41b) of the upper side heating coil 24 and one end (the
20 front end side of the copper pipe 41c) of the lower side heating coil 28 are mutually
connected through copper bus bars 42c to 42e. Further, the other end (the front end side
of the copper pipe 41d) of the lower side heating coil 28 is mutually connected to an
output terminal on the other side of the alternating-current power supply unit 18 through
copper bus bars 42i, 42h, and 42g.
25 As described above, the upper side heating coil 24 and the lower side heating
14
coil 28 are connected in series with respect to the alternating-current power supply unit
18 by the combination of the copper pipes 41 a to 41d (41) and the copper bus bars 42a to
42i (42) and form coils each of which the number of turns is "1". In FIG 3, a large
magnetic flux is generated toward the bottom from the top of a central portion
5 surrounded by the copper pipes 41 and the copper bus bars 42, and the magnetic flux
passes through the steel strip 10, whereby Joule heat is generated in the steel strip 10, so
that the steel strip 10 is heated.
[0020]
In addition, here, in order to clearly illustrate the configurations of the upper
10 side heating coil 24 and the lower side heating coil 28, as shown in FIG 3, the copper
pipes 41a to 41d and the copper bus bars 42a to 42g are connected to each other.
However, when the upper side heating coil 24 and the lower side heating coil 28 are
coiled around the cores 23 and 27, there is a need to pass (attach) the copper pipes 41a to
41d through the slots of the cores 23 and 27. Therefore, in fact, the copper bus bars 42
15 are attached to the copper pipes 41a to 41d to avoid portions where the copper pipes 41
are installed to the cores 23 and 27.
[0021]

FIGS. 4A to 4D are diagrams showing one example of the configuration of the
20 shielding plate 31.
Specifically, FIG 4A is a top view of the shielding plate 31 when viewed from
directly above (the steel strip 10 side). Further, FIG. 4B is a vertical cross-sectional
view as viewed from the direction ofA-A in FIG. 4A. FIG. 4C is a vertical
cross-sectional view as viewed from the direction of B-B' in FIG 4A. FIG. 4D is a view
25 when an area including the shielding plate 31 d shown in FIG. 2C is viewed from directly
15
above the steel strip 10. FIG. 4E is a transverse cross-sectional view as viewed from the
direction of C-C' in FIG 4B. In addition, in FIG. 4D, only a portion which is required
to explain the positional relationship between the steel strip 10 and the shielding plate
31d is shown. Further, in FIG. 4D, eddy currents IE, Isi, and 11,2 which flow in the
5 shielding plate 31d are conceptually shown. In addition, the steel strip 10 is conveyed
in the direction of an arrow shown in the right end in FIGS. 4A and 4D.
In addition, a conveyance direction of the steel strip 10 approximately
corresponds to the depth direction of the shielding plate 31, and a direction (the width
direction of the steel strip 10) perpendicular to the conveyance direction of the steel strip
10 10 on the sheet face approximately corresponds to the width direction of the shielding
plate. Further, the plate thickness (the thickness) direction of the shielding plate 31
approximately corresponds to a direction (the sheet thickness direction of the steel strip
10) perpendicular to the coil face of the heating coil (for example, the upper side heating
coil 24).
15 [0022]
In FIGS. 4A to 4C, the shielding plate 31 is made of copper and has depressed
portions 51a and 51b (51) having the same size and shape. The depressed portions 5la
and 51 b are disposed to have a distance therebetween in the conveyance direction of the
steel strip 10.
20 As shown in FIG. 4A, the shape (the opening shape) in the plate face direction
(the plate thickness direction of the shielding plate 31) of each of the depressed portions
51a and 51b is a rhombus in which each of the corner portions 54a to 54h (54) is
rounded.
In FIG. 4A, a distance P between a corner portion which is an end portion of the
25 depressed portion 51 a and is on the upstream side in the conveyance direction of the steel
16
strip 10 and a corner portion which is an end portion of the depressed portion 51b and is
on the downstream side in the conveyance direction of the steel strip 10 is 150 [mm].
Further, a distance Q between a comer portion which is an end portion of the depressed
portion 51.a and is located in the center in the conveyance direction of the steel strip 10
5 and a comer portion which is an end portion of the depressed portion 5lb and is located
in the center in the conveyance direction of the steel strip 10 is 310 [mm].
[0023]
As shown in FIG. 4D, inthis embodiment, the shielding plate 31 is moved in the
width direction of the steel strip 10 such that a side end 10a of the steel strip 10 and the
10 depressed portions 51a and 51b overlap each other when viewed from the up-and-down
direction. As a specific example thereof, the side end 10a of the steel strip 10 and the
longest portions on the plate face of the depressed portions 51 a and 5 lb (diagonal line
portions of the rounded rhombuses parallel to the conveyance direction of the steel strip
10) overlap each other when viewed from the up-and-down direction (a direction
15 perpendicular to the sheet face of the steel strip 10).
By disposing the shielding plate 31 so as to be in such a positional relationship,
a main magnetic flux, which is generated by operating the induction heating device 20,
and thereby flowing an alternating current in the upper side heating coil 24 and the lower
side heating coil 28, can be shielded by the shielding plate 31. However, eddy currents
20 are generated in both side end portions of the steel strip 10 by the main magnetic flux,
and the eddy current touches the side end of the steel strip, so that a current density in the
side end becomes high and a difference in temperature occurs between the side end and
the vicinity thereof. Therefore, the inventors have found from the results of extensive
studies that the difference in temperature can be reduced by housing non-conductive soft
25 magnetic plates 52a and 52b (52), each of which is composed of a soft magnetic ferrite
17
(for example, a Mn-Zn-based ferrite or a Ni-Zn-based ferrite) or the like, into the
above-mentioned depressed portions 51a and 51b. Here, the non-conductive soft
magnetic plates 52a and 52b can be fixed to the depressed portions 51a and 51b of the
shielding plate 31 using, for example, an adhesive.
5 That is, as shown in FIG. 4D, if a portion of the eddy current I, which flows so
as to go around the end portion of the shielding plate 31 is branched so that the eddy
currents Thl and Ih2 flow along the edges of the depressed portions 51a and S1b, an eddy
current of the steel strip 10 which is generated by magnetic fields that are created by the
eddy currents Ihl and II12 cancels out and weakens an eddy current (an eddy current due to
10 the main magnetic flux) which flows in the side end portion of the steel strip 10. As a
result, the effect of pushing the eddy current which flows in the side end portion of the
steel strip 10 into the inside in the width direction of the steel strip 10 can be produced,
so that homogenization of eddy current density in the vicinity of the side end I Oa of the
steel strip 10 progresses and a difference in temperature between the side end portion (a
15 high-temperature portion) of the steel strip 10 and a portion (a low-temperature portion)
further inside than the side end portion is reduced.
[0024]
Therefore, large eddy currents Ihi and I1,2 need to flow along the edges of the
depressed portions formed in the shielding plate. The inventors have obtained
20 knowledge that in the shielding plate with only a depressed portion simply formed
therein, there is a possibility that the effect of reducing the above-mentioned difference in
temperature cannot be reliably obtained. This is considered to be because an eddy
current continuously flows through the bottom surface of the depressed portion.
Therefore, the inventors have found that by housing the non-conductive soft magnetic
25 plates 52a and 52b in the depressed portions 51a and 5 1b of the shielding plate 31, as
18
described above, it is possible to strengthen a magnetic field which is generated by the
eddy current flowing in the shielding plate 31 due to the main magnetic flux. By the
strengthening of the magnetic field, it is possible to make the magnitude of the eddy
current which is branched from a pathway going around the end portion of the shielding
5 plate 31 larger. As a result, it is possible to make the magnitudes of the eddy currents
I,,, and 11,2 which flow along the edges of the depressed portions 51a and 5lb larger (than
where are the non-conductive soft magnetic plates 52a and 52b not being housed).
For the reason as described above, in this embodiment , the non-conductive soft
magnetic plates (non-conductive soft magnetic materials ) 52a and 52b are housed in the
10 depressed portions 51a and 51b formed in the shielding plate 31. In the case of using
conductive materials in place of the non-conductive soft magnetic plates 52a and 52b,
since the shielding plate itself is conductive, the conductive material and the shielding
plate act as an integrated conductive member, so that it is not possible to strongly limit
the distribution of the eddy current to the edges of the depressed portions 5la and 51 b.
15 In addition, in this embodiment, heat-resistant plates 53a and 53b (53) which
protect the non-conductive soft magnetic plates 52a and 52b from heat from the outside
are disposed on the top (the steel strip 10 side) of the non-conductive soft magnetic plates
52a and 52b in the depressed portions 51a and 51b and fixed thereto by, for example, an
adhesive.
20 [0025]
In FIGS. 4A to 4C, a thickness D of the shielding plate 31 is 25 [mm] and a
depth D,,, of each of the depressed portions 51 a and 51b is 15 [mm]. Each of the
non-conductive soft magnetic plates 52a and 52b has a shape corresponding with the
shape (the shape of a cross -section perpendicular to the thickness direction of the
25 shielding plate 31 ) in the plate face direction of the bottom portion of each of the
19
depressed portions 51 a and 51b, and a thickness DF thereof is 5 [mm]. However, these
dimensions are not limited to the values described above. The inventors have
confirmed that in a frequency range (5 [kHz] to 10 [kHz]) which is used in the induction
heating device 20, if the thickness DF is equal to or more than 1 [mm] (and is equal to or
5 less than the depth of each of the depressed portions 5la and 5lb), in a case where the
non-conductive soft magnetic plates 52a and 52b are housed and a case where the
non-conductive soft magnetic plates 52a and 52b are not housed, a sufficient difference
occurs in the effect of reducing the above-mentioned difference in temperature. Further,
each of the heat-resistant plates 53a and 53b has a shape corresponding with the shape
10 (the shape of a cross-section perpendicular to the thickness direction of the shielding
plate 31) in the plate face direction of the bottom portion of each of the depressed
portions 51 a and 5lb of the shielding plate 31, and a thickness DD thereof is 10 [mm].
As described above, by housing the non-conductive soft magnetic plates 52a and
52b in the depressed portions 5la and 5lb, a magnetic field which is generated by an
15 eddy current flowing in the shielding plate 31 due to the main magnetic flux is
strengthened. By the strengthening of the magnetic field, the magnitudes of the eddy
currents Ihl and Ihz flowing along the edges of the depressed portions 51a and 51b also
become larger. Therefore, magnetic fields which are generated by these large eddy
currents also become large, so that a larger eddy current which cancels out the eddy
20 current flowing in the side end portion of the steel strip 10 can be produced in the
vicinity of the side end portion. Asa result, the effect of sufficiently pushing the eddy
current of the side end portion of the steel strip 10 which is produced by the main
magnetic flux into the inside in the width direction of the steel strip 10 is produced.
[0026]
25 Further, as described above, in this embodiment, the corner portions 54a to 54h
20
of the depressed portions 51 a and 5 tb are rounded. However, it is acceptable if at least
the corner portions 54a and 54e which are the "corner portions on the downstream side in
the conveyance direction of the steel strip 10" of the depressed portions 51a and 51b are
rounded so as to protrude in the downstream side direction and the corner portions 54b
S and 54f which are the "corner portions on the upstream side in the conveyance direction
of the steel strip 10" of the depressed portions 51a and 51b are rounded so as to protrude
in the upstream side direction. If doing so, even if the steel strip 10 moves in a
meandering manner, it is possible to reduce the amount of change in the "overlap length
in the conveyance direction of the steel strip 10" between the side end 10a of the steel
10 strip and each of the depressed portions 51a and Sib" when viewed from the
up-and-down direction, and it is also possible to reduce the amount of change in the
effect of pushing the eddy current of the side end portion of the steel strip 10 further
toward the inside than the side end portion. Further, as described above, since the eddy
currents I,,, and 11,2 flowing along the edges of the depressed portions 51a and 51b
15 become large due to the non-conductive soft magnetic plates 52a and 52b, even if the
steel strip 10 moves in a meandering manner, the magnitudes of the eddy currents Iii, and
I1,2 and the effect of pushing the eddy current flowing in the side end portion of the steel
strip 10 further toward the inside than the side end portion can be maintained to some
extent. Therefore, even if the steel strip 10 moves in a meandering manner, a change in
20 temperature distribution in the width direction of the steel strip 10 can be reduced.
[0027]
[Example]
FIG. 5 is a diagram showing one example of the relationship between the
amount of insertion of the shielding plate and a width temperature deviation ratio.
25 The amount of insertion of the shielding plate corresponds to the "overlap length
21
R in the width direction of the steel strip 10" between each of both side end portions of
the steel strip 10 and each shielding plate (refer to FIG. 213). Further, the width
temperature deviation ratio is a value (=sheet width central portion temperature/sheet end
portion temperature) obtained by dividing the temperature of the central portion in a
5 temperature distribution in the width direction of the steel strip 1.0 (the sheet width
central portion temperature) by the temperature of the end portion (the sheet end portion
temperature).
In FIG. 5, in a graph Al, a plain shielding plate in which no depressed portion is
formed is used. In a graph A2, a shielding plate having the depressed portions in which
10 the non-conductive soft magnetic plates are housed, as in this embodiment, is used.
[0028]
Here, the graphs shown in FIG. 5 are based on the results of experiments
performed under the following conditions.
Heating coil width: 1300 [mm]
15 Material of core: ferrite
Material to be heated: stainless steel sheet (width of 900 [mm], and
thickness of 0.3 [mm])
Gap between coils: 180 [mm]
Sheet conveyance speed : 50 [mpm (m/min.)]
20 Heating temperature : 400 to 730 [°C] (the temperature increase of
the center; is set to be 330 [°C])
Power-supply frequency : 8.5 [kHz]
Current: 3650 [AT]
Material of shielding plate: copper
25 External dimensions of shielding plate: width of 230 [mm], depth of 600
22
[mm], and thickness of 25 [mm]
Shape of depressed portion of shielding plate: FIG 4A (graph A2)
Material of non-conductive soft magnetic plate: Ni-Zn ferrite
Thickness of non-conductive soft magnetic plate: 5 [mm]
5 Standard of amount of insertion of shielding plate: 90 [mm]
[0029]
In FIG 5, it can be found that the smaller the width temperature deviation ratio
(the closer to 1 the width temperature deviation ratio), the more uniform a temperature
distribution in the width direction of the steel strip 10 can be. Further, it can be found
10 that the smaller the slope of the graph, the greater the change in temperature distribution
in the width direction of the steel strip 10 can be reduced even if the steel strip 10 moves
in a meandering manner.
In FIG. 5, it can be found that if the shielding plate having the depressed portions
in which the non-conductive soft magnetic plates are housed is used, as in this
15 embodiment, both the smoothing of a temperature distribution in the width direction of
the steel strip 10 and reduction of a change in the temperature distribution in the width
direction of the steel strip 10 at the time of meandering of the steel strip 10 can be
realized.
[0030]
20 [Summary]
As described, in this embodiment, the shielding plate 31 is disposed between the
side end portion of the steel strip 10 and each of the cores 23 and 27 (the upper side
heating coil 24 and the lower side heating coil 28). In the shielding plate 31, two
depressed portions 51a and 51b are formed so as to have a distance therebetween in the
25 conveyance direction of the steel strip 10. In addition, the non-conductive soft
23
magnetic plates 52a and 52b are housed in the depressed portions 51 a and 51b.
Therefore, it is possible to strengthen a magnetic field which is generated by the eddy
current flowing in the shielding plate 31d due to the main magnetic flux and make the
magnitudes of the eddy currents Ihl and Ih2 flowing along the edges of the depressed
5 portions 104a and 104b larger. As a result, the smoothing of a temperature distribution
in the width direction of the steel strip 10 can be realized. Further, by flowing the large
eddy currents I111 and Ih2 along the edges of the depressed portions 5la and 5lb in this
manner, even if the steel strip 10 moves in a meandering manner, the effect in which the
eddy currents Ih, and 11,2 push the eddy current flowing in the side end portion of the steel
10 strip 10 further toward the inside than the side end portion can be maintained to some
extent. Accordingly, even if the steel strip 10 moves in a meandering manner, a change
in temperature distribution in the width direction of the steel strip 10 can be reduced. In
addition, even in a case where the steel strip 10 moves in a meandering manner, a
magnetic field which is generated by the eddy current flowing in the shielding plate 31d
15 pushes the side end of the steel strip 10 back to the center in the width direction of the
steel strip 10, so that meandering of the steel strip 10 can be suppressed.
[0031]
Further, in this embodiment, the corner portions 54a and 54e which are the
"comer portions on the downstream side in the conveyance direction of the steel strip 10'
20 of the depressed portions 51a and 51b are rounded so as to protrude in the downstream
side direction and the corner portions 54b and 54f which are the "corner portions on the
upstream side in the conveyance direction of the steel strip 10" of the depressed portions
5la and 51b are rounded so as to protrude in the upstream side direction. Therefore,
even if the steel strip 10 moves in a meandering manner, it is possible to reduce the
25 amount of change in the "overlap length in the conveyance direction of the steel strip 10"
24
between the side end IOa of the steel strip and each of the depressed portions 51 a and
51b" when viewed from the up-and-down direction, so that the amount of change in the
push-in effect of the eddy current flowing in the side end portion of the steel strip 10 can
also be reduced. Accordingly, a change in temperature distribution in the width
5 direction of the steel strip 10 when the steel strip 10 moves in a meandering manner can
be even further reduced.
[0032]
Further, in this embodiment, since the heat-resistant plates 53a and 53b are
disposed on the top (the steel strip 10 side) of the non-conductivc soft magnetic plates
10 52a and 52b, even if the induction heating device is used under high temperature,
degradation of the characteristics of the non-conductive soft magnetic plates 52a and 52b
can be prevented. However, in a case where the induction heating device is not used
under high temperature, there is no need to necessarily use the heat-resistant plates 53a
and 53b. Ina case where the heat-resistant plates 53a and 53b are not used in this
15 manner, the thickness of the non-conductive soft magnetic plate which is housed in the
depressed portion of the shielding plate may also be set to be the same as the depth of the
depressed portion. In this manner, the thickness of the non-conductive soft magnetic
plate may also be the same as the depth of the depressed portion and may also be less
than the depth of the depressed portion.
20 [0033]
[Modified Examples]

FIGS. 6A to 6C are diagrams showing modified examples of the configuration
of the shielding plate. FIGS. 6A and 6B respectively show the first and the second
25 modified examples of the shielding plate and are diagrams showing the shielding plate
25
when viewed from directly above (from the steel strip 10 side). These drawings
correspond to FIG 4A.
In FIG. 6A, a shielding plate 61 is made of copper and has depressed portions
62a and 62b (62) disposed to have a distance therebetween in the conveyance direction of
5 the steel strip 10 and having the same size and shape. In these points, the shielding
plate 61 is the same as the shielding plate 31 shown in FIGS. 4A to 4C. However, as
shown in FIG. 6A, the shape (the opening shape) in the plate face direction of the
depressed portion 62a is a triangle which is tapered off toward the upstream side from the
downstream side in the conveyance direction (a direction of an arrow shown in FIGS. 6A
10 and 6B) of the steel strip 10 and in which the corner portions 64a to 64c (64) are rounded.
In such a case, it is preferable that at least the corner portion 64a which is a "corner
portion on the upstream side in the conveyance direction of the steel strip 10" of the
depressed portion 62a be rounded so as to protrude in the upstream side direction.
[0034]
15 Further, the shape (the opening shape) in the plate face direction of the
depressed portion 62b is a triangle which is tapered off toward the downstream side from
the upstream side in the conveyance direction of the steel strip 10 and in which the corner
portions 64d to 64f (64) are rounded. In such a case, it is preferable that at least the
corner portion 64d which is a "corner portion on the downstream side in the conveyance
20 direction of the steel strip 10" of the depressed portion 62b be rounded so as to protrude
in the downstream side direction.
Further, the non-conductive soft magnetic plates and the heat resistant plates 63a
and 63b (63), each of which has a shape corresponding with the shape (the shape of a
cross-section perpendicular to the thickness direction of the shielding plate 61) in the
25 plate face direction of the bottom portion of each of the depressed portions 62a and 62b,
26
are housed in the depressed portions 62a and 62b and fixed thereto using an adhesive or
the like.
[0035]
Further, in FIG 6B, a shielding plate 71 is made of copper. As shown in FIG.
5 6B, the number of depressed portions 72 which are formed in the shielding plate 71 is
one. As shown in FIG. 6B, the shape in the plate face direction of the depressed portion
72 is a shape in which the "corner portion (the corner portion 54b ) on the upstream side
in the conveyance direction of the steel strip 10" of the depressed portion 51 a shown in
FIGS. 4A to 4C and the "corner portion (the comer portion 54e ), on the downstream side
10 in the conveyance direction of the steel strip 10" of the depressed portion 5lb are
connected to each other, and the corner portions 74a to 74f (74) are rounded. Further, a
non-conductive soft magnetic plate and a heat resistant plate 73, each of which has a
shape corresponding with the shape (the shape of a cross-section perpendicular to the
thickness direction of the shielding plate 71) in the plate face direction of the bottom
15 portion of the depressed portion 72, are housed in the depressed portion 72 and fixed
thereto using an adhesive or the like.
[0036]
As described above, it is preferable that a portion (a second portion) which is
tapered off toward the upstream side from the downstream side in the conveyance
20 direction of the steel strip 10 and a portion (a first portion) which is tapered off toward
the downstream side from the upstream side in the conveyance direction of the steel strip
10 be included in the depressed portion which is formed in the shielding plate. The first
portion and the second portion may also be formed individually (FIGS. 4A and 6A) and
may also be formed integrally (FIG. 6B). In addition, it is preferable that the tapered
25 first and second portions face each other in the conveyance direction of the steel strip 10.
27
If the shape in the plate face direction of the depressed portion is such a shape, it
becomes possible to form the edge of the depressed portion of the shielding plate
according to a pathway of an eddy current flowing through the steel strip 10. Further, in
this case, it is preferable that at least the tapered end portion (the tapered portion) among
5 the "corner portions on the upstream side and the downstream side in the conveyance
direction of the steel strip 10" of the depressed portion be rounded.
In addition, the shape (the opening shape) in the plate face direction of the
depressed portion which is formed in the shielding plate may also be any shape and the
number thereof may also be 1 and may also be 2 or more.
10 [0037]
Further, it is preferable that a portion (a third portion) which is tapered off
toward a side close to the central portion in the width direction (a direction perpendicular
to the conveyance direction) of the conductive sheet from a side away from the central
portion in the width direction of the conductive sheet be included in the depressed
15 portion . In this case, it is possible to gradually increase the amount of change in the
effect in which the magnetic field that is generated by the eddy current flowing in the
shielding plate pushes the side end of the steel strip into the center side in the width
direction of the steel strip , so that suppression of meandering of the conductive sheet can
be more flexibly controlled . For example, in FIG. 4A, two third portions are included in
20 the two depressed portions 51a and 5lb of the shielding plate 31 . In addition, only a
single depressed portion may be formed in the shielding plate and the third portion may
be included in the single depressed portion . However, if a plurality of third portions is
included in the depressed portion of the shielding plate, it is possible to more uniformly
produce the above-mentioned push-in effect. Further, a portion (a fourth portion) which
25 is tapered off toward a side away from the central portion in the width direction of the
28
conductive sheet from a side close to the central portion in the width direction of the
conductive sheet may also be included.
[0038]
FIG. 6C shows the third modified example of the shielding plate and is a vertical
5 cross-sectional views of the shielding plate when cut in the thickness direction of the
shielding plate along the conveyance direction of the steel strip 10. FIG 6C
corresponds to FIG. 4B.
In FIG 6C, a shielding plate 81 is made of copper and has depressed portions
82a and 82b (82) disposed to have a distance therebetween in the conveyance direction of
10 the steel strip 10 and having the same size and shape. Further, the shape (the opening
shape) in the plate face direction of each of the depressed portions 82a and 82b is a
rhombus in which each corner portion is rounded. In this manner, the shielding plate 81
shown in FIG. 6C and the shielding plate 31 shown in FIGS. 4A to 4C are the same in
material, shape, and size. However, the shielding plate 81 shown in FIG. 6C is formed
15 by superimposing an upper plate 84a and a lower plate 84b on each other and fixing them
to each other.
As described above, the shielding plate may also be integrally formed and may
also be formed by combining a plurality of members.
Moreover, although in this embodiment, the shielding plate is made of copper,
20 the shielding plate is not limited to a copper plate. That is, provided that the shielding
plate is a conductor, preferably, a conductor having a relative permeability of 1, the
shielding plate may also be formed of any material. For example, the shielding plate
can be formed of aluminum.
[0039]
25 In addition, in this embodiment, by increasing the magnitude of the eddy current
29
in the shielding plate which is generated in the vicinity of the non-conductive soft
magnetic plate (the non-conductive soft magnetic material), the magnitude of the eddy
current which flows in the side end portion of the steel strip (the conductive sheet) 10 due
to the main magnetic flux is reduced. Further, since the conductive shielding plate is
5 interposed between the core (or, the heating coil) and the non-conductive soft magnetic
plate, direct passage of the main magnetic flux through the non-conductive soft magnetic
plate can be avoided. For this reason, it is acceptable if the induction heating device
includes the heating coil, the core, the conductive shielding plate which is disposed
between the core and the side end portion in a direction perpendicular to the conveyance
10 direction of the steel strip, and the non-conductive soft magnetic plate which is attached
to the shielding plate such that the shielding plate is interposed between the core and the
non-conductive soft magnetic plate.
[0040]
For this reason, for example, shielding plates in which the non-conductive soft
15 magnetic plates as shown in FIGS. 7A to 7C and 8A to 8C are mounted can be used. In
addition, FIGS. 7A to 7C are vertical cross -sectional views showing one example of the
configuration of each of shielding plates in the fourth to the sixth modified examples of
this embodiment. Further, FIGS . 8A to 8C are perspective views showing one example
of the configuration of each of shielding plates in the seventh to the ninth modified
20 examples of this embodiment.
In the fourth modified example of this embodiment shown in FIG 7A,
non-conductive soft magnetic plates 102a and 102b (102) are disposed on a flat shielding
plate 101 and the non-conductive soft magnetic plates 102 face the side end portion of
the steel strip. In this manner, the non-conductive soft magnetic plates may also be
25 mounted on the shielding plate such that protruded portions are formed on the shielding
30
plate, without forming a depressed portion in the shielding plate. In this case, it is
possible to increase an eddy current in the shielding plate in a peripheral portion of the
contact surface between the shielding plate and the non-conductive soft magnetic plate.
However, since by forming a depressed portion in a shielding plate and disposing a
5 non-conductive soft magnetic plate in the depressed portion, an eddy current can be
constrained in an edge of the depressed portion and the distance between an edge of the
depressed portion and the non-conductive soft magnetic plate can be reduced, it is
possible to secure a larger eddy current at the edge of the depressed portion. For this
reason, as shown in FIG 7B (the fifth embodiment), it is also acceptable that depressed
10 portions 114a and 114b (114) be formed in a shielding plate 111 and non-conductive soft
magnetic plates 112a and 112b (112) be mounted in the depressed portions 114 of the
shielding plate 111 such that protruded portions are formed on the shielding plate 111.
Further, as shown in FIG. 7C (the sixth embodiment), non-conductive soft magnetic
plates 122a and 122b (122) in which the shape of the upper surface and the shape of the
15 lower surface are different from each other may also be mounted in depressed portions
124a and 124b (124) of a shielding plate 121.
[0041]
Further, in the seventh modified example shown in FIG. 8A, a non-conductive
soft magnetic plate 202 is mounted on a shielding plate 201 having protruded portions
20 (two rhombic portions) 205a and 205b (205). In this case, it is possible to increase eddy
currents flowing in edges of the protruded portions 205. Further, the shape (the outer
peripheral shape) of the shielding plate is not particularly limited. In the eighth
modified example shown in FIG. 8B, depressed portions (two rhombic portions) 214a
and 214b (214) are formed in a shielding plate 211 and the shielding plate 211 has frame
25 portions 216a and 216b following the outer peripheral shapes (the opening shapes) of the
31
depressed portions 214. Further, non-conductive soft magnetic plates 212a and 212b
(212) are housed in the depressed portions 214. In this case, it is possible to increase
eddy currents flowing in edges of the depressed portions 214. Further, in the ninth
modified example shown in FIG 8C, protruded portions (two rhombic portions) 225a and
5 225b (225) are formed on a shielding plate 221 and the shielding plate 221 has an outer
peripheral shape similar to (following) the outer peripheral shapes (the base end shapes)
of the protruded portions 225. Further, a non-conductive soft magnetic plate 222 is
disposed on the shielding plate 221 so as to surround edge portions of the protruded
portions 225. In this case, it is possible to increase eddy currents flowing in edges of
10 the. protruded portions 225.
[0042]
In addition, a heat-resistant plate may also be mounted on the non-conductive
soft magnetic plate in each modified example shown in FIGS. 7A to 7C and 8A to 8C.
Further, the shape and the number of depressed portions or protruded portions of the
15 shielding plate in the plate face direction are not particularly limited. Further, the shape
and the number of non-conductive soft magnetic plates are also not particularly limited.
[0043]
It is preferable to make the magnitude of the eddy current in the shielding plate
which flows through the vicinity of the non-conductive soft magnetic plate, as large as
20 possible. In the following, the configuration of making the eddy current larger will be
described.. ,
FIG. 4E is a cross-sectional view as viewed from a direction of C-C' in FIG 4B.
As shown in FIG. 4E, the non-conductive soft magnetic plates 52a and 52b (52) are
included in the cross section, and a boundary portion (a boundary line) between the
25 shielding plate 31 and each of the non-conductive soft magnetic plates 52 describes a
32
closed curve (a total of two closed curves). That is, a case where the shielding plate
surrounds the non-conductive soft magnetic plate and a case where the non-conductive
soft magnetic plate surrounds the shielding plate are included in the cross section. In
this manner, if the shielding plate has a cross section perpendicular to the thickness
5 direction including the non-conductive soft magnetic material (a cross section parallel to
the coil face), the distance between the non-conductive soft magnetic plate and the eddy
current in the shielding plate, which is strengthened by the non-conductive soft magnetic
plate, can be shortened. Further, the above-mentioned boundary portion describes a
closed curve (is ring-shaped), whereby an area of an eddy current which is strengthened
10 can increase and the characteristic of the non-conductive soft magnetic plate can be fully
utilized. In addition, in order to make the magnitude of the eddy current in the shielding
plate which flows through the vicinity of the non-conductive soft magnetic material, as
large as possible, it is preferable that the shielding plate and the non-conductive soft
magnetic material be in contact with each other. However, a space (a space as a
15 boundary portion) may also be present between the shielding plate and the
non-conductive soft magnetic material such that the non-conductive soft magnetic
material can be easily attached to the shielding plate.
[0044]
Further, in the case of using the induction heating device under high temperature
20 or the case of rapidly heating the steel strip, the temperature of the shielding plate
sometimes becomes high due to an eddy current. In this case, it is preferable to cool the
shielding plate and the non-conductive soft magnetic material using a cooler such as a
water-cooling pipe. This cooling method is not particularly limited. For example, the
shielding plate may also be cooled by integrally forming a water-cooling line in the
25 shielding plate, or the shielding plate may also be cooled by sending a gas to the
33
shielding plate by a blower,
[0045]

A material constituting the non-conductive soft magnetic plate is not limited to a
5 soft magnetic ferrite, provided that it is a non-conductive soft magnetic material.
Further, the non-conductive soft magnetic material may also be a material in which
powder or particles are packed or compacted, or a material in which a plurality of blocks
is combined, rather than a plate. Further, the shape of the non-conductive soft magnetic
plate is not particularly limited. If it is possible to dispose a non-conductive soft
10 magnetic plate according to the portion (for example, the edge of the depressed portion)
of the inside of the shielding plate, in which the eddy current flows, since it is possible to
obtain a magnetic field which enhances the eddy current, for example, the
non-conductive soft magnetic plate may also have a hollow portion. However, in order
to sufficiently use the magnetism of the non-conductive soft magnetic plate, it is
15 preferable that the non-conductive soft magnetic plate be solid.
The heat-resistant plate also need not necessarily be a plate and may also be any
material, provided that a heat-resistant material is used.
Further, a method of fixing the non-conductive soft magnetic plate and the
heat-resistant plate which are housed in the depressed portion , to the inside of the
20 depressed portion is not limited to a method using an adhesive. For example, it is
possible to fix them to the depressed portion using a screw with insulation secured
between the shielding plate and the non-conductive soft magnetic plate and the
heat-resistant plate.
[0046]
25
34
In this embodiment, the disposition place of the induction heating device 20 is
not limited to the position shown in FIG 1. That is, provided that it is possible to
inductively heat a conductive sheet by a transverse method, the induction heating device
20 may also be disposed anywhere. For example, the induction heating device 20 may
S also be disposed in the second container 12. Further, the induction heating device 20
may also be applied to places other than the continuous annealing line.
Further, in, this embodiment, a case where the heating coil width and the gap
between the heating coils are equal to each other has been described as an example.
However, the heating coil width and the size of the gap are not particularly limited.
10 However, it is preferable that the heating coil width be equal to or greater than the gap (or,
the heating coil width be greater than the gap). In this case, a main magnetic field
which is generated from the induction heating device 20 becomes more than a leak
magnetic field, thereby being able to improve the heating efficiency of the induction
heating device 20. In addition, the upper limit of the heating coil width can be
15 appropriately determined according to the conditions such as a space where the induction
heating device 20 is disposed, or the weight or the cost which is required for the
induction heating device 20. Further, the numbers of heating coils and cores disposed
are not particularly limited. For example, a plurality of the heating coil and the core can
be disposed in the conveyance direction of the steel strip in order to flexibly perform the
20 heating control of the steel strip.
In addition, the number of shielding plates disposed is also not particularly
limited. For example, a plurality of the shielding plates may also be disposed in the
conveyance direction of the steel strip in accordance with the numbers of heating coils
and cores disposed. A plurality of shielding plates having a single depressed portion
25 may also be disposed to form a shielding plate unit having a plurality of depressed
35
portions.
Further, in this embodiment, a case where the upper side inductor 21 and the
lower side inductor 22 are provided has been shown as an example. However, only one
of either the upper side inductor 21 or the lower side inductor 22 may also be provided.
5 [0047]
In addition, all the embodiments of the present invention described above
merely show examples embodied in implementation of the present invention and the
technical scope of the present invention should not be construed as being limited by these.
That is, the present invention can be implemented in various forms without departing
10 from the technical idea thereof or the main features thereof.
Industrial Applicability
[0048]
A transverse flux induction heating device is provided which allows unevenness
15 of a temperature distribution in the width direction of a conductive sheet of a heating
target to be reduced and allows variation in temperature distribution in the width
direction of the conductive sheet of the heating target due to meandering of the
conductive sheet to be reduced.
20 Reference Symbol List
[0049]
10: steel strip (conductive sheet)
18: alternating-current power supply unit
20: induction heating device
25 21: upper side inductor
36
22: lower side inductor
23, 27: core
24: upper side heating coil (heating coil)
28: lower side heating coil (heating coil)
5 31, 61, 71, 81, 101 , 111, 121, 201, 211 , 221: shielding plate
51, 62, 72, 82, 114, 124, 214: depressed portion
205, 225: protruded portion
52, 102, 112, 122, 202, 212, 222: non-conductive soft magnetic plate
(non-conductive soft magnetic material)
10 53, 63, 73: heat-resistant plate (heat-resistant material)
3'7
What is claimed is:
1. A transverse flux induction heating device which allows an alternating magnetic
field to intersect a sheet face of a conductive sheet which is conveyed in one direction,
5 thereby inductively heating the conductive sheet, the transverse flux induction heating
device comprising:
a heating coil disposed such that a coil face faces the sheet face of the
conductive sheet;
a core around which the heating coil is coiled;
10 a shielding plate formed of a conductor and disposed between the core and a
side end portion in a direction perpendicular to a conveyance direction of the conductive
sheet; and
a non-conductive soft magnetic material which is attached to the shielding plate,
wherein the shielding plate is interposed between the core and the
15 non-conductive soft magnetic material.
2. The transverse flux induction heating device according to claim 1, further
comprising a heat-resistant plate which is attached to the non-conductive soft magnetic
material,
20 wherein the heat-resistant plate is disposed closer to the conductive sheet than
the non-conductive soft magnetic material.
3. The transverse flux induction heating device according to claim 1, wherein the
shielding plate has a cross section parallel to the coil face, the cross section including the
25 non-conductive soft magnetic material.
4. The transverse flux induction heating device according to claim 1, wherein
a depressed portion which faces the side end portion in the direction
perpendicular to the conveyance direction of the conductive sheet is formed in a surface
5 of the shielding plate, the surface facing the conductive sheet, and
the non-conductive soft magnetic material is housed in the depressed portion.
5. The transverse flux induction heating device according to claim 4, wherein a portion
which is tapered off toward a side close to a central portion in the direction perpendicular
10 to the conveyance direction of the conductive sheet from a side away from the central
portion in the direction perpendicular to the conveyance direction of the conductive sheet
is included in the depressed portion.
6. The transverse flux induction heating device according to claim 4, wherein
15 a first portion which is tapered off toward a downstream side from an upstream
side in the conveyance direction of the conductive sheet and a second portion which is
tapered off toward the upstream side from the downstream side in the conveyance
direction of the conductive sheet are included in the depressed portion, and
The first portion and the second portion face each other in the conveyance
20 direction ofthe conductive sheet.
7. The transverse flux induction heating device according to claim 6, wherein
the first portion is rounded toward the downstream side, and
the second portion is rounded toward the upstream side.