DESCRIPTION
Invention Title
STEEL STRIP STABILIZING APPARATUS
5 Technical Field
The present invention relates to a steel strip
stabilizing apparatus which corrects a shape of a steel
strip, particularly, a transferred plated steel plate or
damps vibrations of the plated steel strip in a non-contact
10 manner.
More particularly, the present invention relates to a
steel strip stabilizing apparatus which increases (electro)
magnetic attraction force with respect to a plated steel
strip passing through a plating bath to effectively correct
15 a shape (curvature) or suppress (damp) vibrations in the
plated steel strip, thereby ultimately improving quality in
plating of the steel strip.
Background Art
20 In recent years, demand for (zinc) plated steel
strips, which enhance corrosion resistance, etc., have
desirable aesthetic qualities, and in particular, are used
as steel sheets for electronic products or automobiles, has
rapidly increased.
Page 2
FIG. 1 illustrates a process for plating a steel
strip, particularly, a zinc-plating process.
For example, as shown in FIG. 1, a zinc plating
process for steel strips is performed by allowing molten
5 zinc to be attached to surfaces of a steel strip (for
example, a cold-rolled steel strip) 100 while the steel
strip passes through a snout and a zinc plating bath 110
after the steel strip is unwound from a pay-off reel and is
thermally treated with a welding machine and a looper.
10 Here, a gas wiping device (for example, an air knife)
120 provided directly above the plating bath may spray a
gas (for example, an inert gas or air) onto a surface of
the steel strip to properly reduce the amount of zinc
plated on the steel strip, thereby controlling the plating
15 thickness of the steel strip.
Also, the plated steel strip may continuously pass
through a sink roll 112 that allows the steel strip to pass
through the plating bath 110 and adjusts a tension of the
steel strip, a stabilizing roll 114, which are provided in
20 the plating bath 110, and an upper transfer roll 130.
As shown in FIG. 1, the molten zinc filled in the
zinc plating bath 110 may have a temperature of about 450°C
to about 460°C. The steel strip 100 passing through the
plating bath 110 may have various types, widths, and
25 thicknesses.
Page 3
However, loads applied to (a roll shaft of) the sink
roll 112 may be generally different according to types of
steel strips. For example, a maximum load of about 500 kgf
may be applied to both ends of the sink roll 112. Thus,
5 when dynamical properties such as vibration occur, a
maximum load of about 100 kgf may be applied to both ends
of the sink roll 112 in a rotation direction of the sink
roll 112.
Thus, while the plated steel strip 100 passing
10 through the sink roll 112 and the stabilizing roll 114
passes through the upper transfer roll 130, vibrations in
the steel strip 100 may occur even if the vibrations are
varied according to the types, widths, or thickness of
steel strips. Here, the occurrence of the vibration in the
15 steel strip may cause a plating deviation between the gas
wiping device 120 and the steel strip, resulting in a
plating failure.
On the other hand, when a curvature phenomenon (for
example, a C-shaped curvature or S-shaped curvature
20 phenomenon in which a central portion of the steel strip is
recessed or curved in a width direction of the steel strip)
in which the steel strip is non-uniform in shape occurs, a
plating deviation in the width direction of the steel strip
may occur, thus resulting in the plating failure.
25 Thus, as shown in FIG. 1, at least one steel strip
Page 4
stabilizing apparatus (a so-called a “steel strip damping
apparatus”) 140 for correcting the shape of the steel strip
or suppressing vibration in the steel strip may be disposed
between the gas wiping device 120 and the upper transfer
5 roll 130.
The steel strip stabilizing apparatus 140 may damp
(suppress) the vibrations in the plated steel strip or
control the curvature shape in the steel strip to transfer
the steel strip in a state in which the steel strip is flat,
10 thereby preventing the plating deviation from occurring.
Although schematically shown in FIG. 1, the steel
strip stabilizing apparatus 140 according to the related
art may damp vibrations in the steel strip or correct the
shape of the steel strip by using a mechanical touch roll
15 that is in contact with the steel strip or spraying a gas
onto the steel strip.
However, in the case of using the mechanical touch
roll, since the roll contacts the surface of the
transferred plated steel strip in a state in which the
20 molten zinc is not completely attached (dried) to the
surface of the steel strip by passing through the gas
wiping device, a surface roll marker may be easily formed
on the surface of the plated steel strip, and particularly,
foreign matters may be attached to the surface of the steel
25 strip by using the touch roll as a medium to cause quality
Page 5
defects in the plated steel strip.
For example, since most steel strips for vehicles are
used in vehicle frames, the surface defects in the steel
strip may cause significant quality defects in products.
5 Also, the contact type roll may cause vibrations and noise
due to abrasion thereof and also increase vibrations in the
transferred plated steel strip due to unstable rotation
thereof.
The related-art method for damping vibrations in the
10 steel strip or correcting the shape of the steel strip by
spraying the gas onto the steel strip may have limitations
in which vibration suppression and shape correction in the
steel strip are inefficient, and particularly, if the gas
is sprayed onto the surface of the steel strip in the state
15 where a plating solution is completely dried and thus is
not attached to the surface of the steel strip, it may have
an influence on the plating thickness of the steel strip.
Accordingly, a technique which enables the steel
strip to be corrected in shape and damped (suppressed) in
20 vibrations through a steel strip non-contact manner instead
of the mechanical contact or gas spraying manner is
required. For this, a method using electromagnetic force
has been proposed as the other method in the related art.
However, in the case of the related-art method using
25 the electromagnetic force, even in the case that the steel
Page 6
strip is suppressed in vibrations or corrected in shape
through magnetic attraction force with respect to the steel
strip in the non-contact manner, this may be merely a
simple configuration in which a magnet block for generating
5 magnetic fields (magnetic force) is disposed adjacent to
the steel strip. Also, since the magnet block has a small
unit area, the magnet block may cause stress concentration
in the steel strip when the steel strip is damped in
vibration and corrected in shape.
10 For example, in a case of a thin film having a thin
thickness of about 0.6 t, a steel strip may be dented to
cause surface defects of the steel strip.
Furthermore, as demand for plated steel strips used
as steel strip for vehicles is rapidly increasing, large-
15 scaled plating equipment and high-speed plating may be
required. However, the related-art steel strip stabilizing
apparatus using the simple magnet block structure may have
limitations in use.
20 Disclosure
Technical Problem
An aspect of the present invention provides a steel
strip stabilizing apparatus which improves shape correction
or vibration damping (vibration suppression) in a steel
Page 7
strip, i.e., a plated steel strip to prevent a plating
deviation from occurring in the steel strip, thereby
ultimately improving quality in plating of the steel strip.
Another aspect of the present invention provides a
5 steel strip stabilizing apparatus which measures a gap
(distance) between the apparatus and a steel strip by using
a non-contact type eddy current sensor to accurately
maintain the distance between the apparatus and the steep
strip on the basis of quick response characteristics,
10 thereby further improving shape correction or vibration
damping in the steel strip, and also, maintains a magnetic
field generating pole at a contact temperature to improve a
life-cycle of the apparatus.
Another aspect of the present invention provides a
15 steel strip stabilizing apparatus in which an apparatus
support body or a magnetic field generating pole is cooled
to stably correct a shape of a steel strip or suppress
vibrations of the steel strip through (electro) magnetic
attraction force.
20
Technical Solution
According to an aspect of the present invention,
there is provided a steel strip stabilizing apparatus
including: an apparatus support body disposed on at least
25 one side of a traveling steel strip; and a steel strip
Page 8
stabilizing unit including a magnetic field generating pole
disposed on the apparatus support body to face the steel
strip and a pole expansion part configured to provide steel
strip attraction force to a steel strip-side end of the
5 magnetic field generating pole.
The pole expansion part of the steel strip
stabilizing unit may have a size greater than a thickness
of at least the magnetic field generating pole by using a
rounded portion disposed on a front end of the magnetic
10 field generating pole as a medium.
At least one steel strip stabilizing unit may be
disposed on the apparatus support body, and at least one
apparatus support body may be arranged in a width direction
of the steel strip.
15 The magnetic field generating pole may be provided in
plurality on the apparatus support body, and the plurality
of magnetic field generating poles may be independently
provided or connected to each other by using a connection
part as a medium in a traveling direction of the steel
20 strip on the apparatus support body.
The steel strip stabilizing unit may include one of a
coil-type steel strip stabilizing unit of which the
magnetic field generating pole is constituted by a core
member formed of a magnetic material and an electromagnetic
25 coil wound around the core member and a magnet-type steel
Page 9
strip stabilizing unit of which the magnetic field
generating pole includes a permanent magnet or
electromagnet to correct a shape of the steel strip or
suppress vibrations of the steel strip.
5 The electromagnetic coil may be wound around at least
one of the plurality of magnetic field generating poles
connected to each other by using the connection part as the
medium.
The pole expansion part disposed on the magnetic
10 field generating pole may have a width greater about oneand-
a half times to about five times than a diameter of the
electromagnetic coil wound around the core member of the
coil-type steel strip stabilizing unit or than a thickness
of the magnetic field generating pole of the magnet-type
15 steel strip stabilizing unit.
The electromagnetic coil of the coil-type steel strip
stabilizing unit may be provided on the core member in
parallel.
The steel strip stabilizing apparatus may further
20 include at least one of an eddy current sensor and a
distance sensor which are configured to measure a gap
between the pole expansion part and the steel strip.
The steel strip stabilizing apparatus may further
include a cooling unit provided in one or all of the
25 apparatus support body and the magnetic field generating
Page 10
pole disposed on the apparatus support body.
Advantageous Effects
According to the present invention, the (electro)
5 magnetic attraction force with respect to the steel strip
may increase, and the magnetic field generating pole having
various shapes may be provided to control the applied
current. As a result, the shape correction and/or
vibration damping in the plated steel strip may be improved,
10 and thus, plating deviations in the steel strip may be
reduced to improve the plating quality of the steel strip.
Also, the (electro) magnetic force may be used to
prevent the steel strip surface defects due to the existing
mechanical contact manner from occurring and also prevent
15 contact abrasion from occurring. Thus, the steel strip
stabilizing apparatus may be semipermanently used.
Furthermore, the gap (distance) between the apparatus
and the steel strip may be measured by using the eddy
current sensor (or the distance sensor) on the basis of the
20 accurate and quick response characteristics to control the
gap between the steel strip and the apparatus. As a result,
the (electro) magnetic attraction force with respect to the
steel strip may be uniformly controlled or maintained to
uniformly correct the shape of the steel strip or damp
25 vibrations of the steel strip.
Page 11
5
Also, the apparatus support body or the magnetic
field generating pole may be cooled to stably correct the
shape of the steel strip or suppress vibrations of the
steel strip through the (electro) magnetic attraction force.
Description of Drawings
The above and other aspects, features and other
advantages of the present invention will be more clearly
understood from the following detailed description taken in
10 conjunction with the accompanying drawings, in which:
FIG. 1 is a schematic view of a steel strip plating
process according to a related art;
FIG. 2 is a schematic view illustrating an example of
a steel strip plating process using a steel strip
15 stabilizing apparatus according to the present invention;
FIG. 3 is a perspective view of the steel strip
stabilizing apparatus of FIG. 2 according to the present
invention;
FIGS. 4A and 4B are side views illustrating various
20 shapes of the steel strip stabilizing apparatus according
to the present invention;
FIG. 5 is a side view of the steel strip stabilizing
apparatus of FIG. 3 according to the present invention:
FIGS. 6A and 6B are perspective and side views
25 illustrating a magnetic field generating pole of the steel
Page 12
strip stabilizing apparatus according to an embodiment of
the present invention;
FIGS. 7A and 7B are perspective and side views
illustrating a magnetic field generating pole of a steel
5 strip stabilizing apparatus according to another embodiment
of the present invention;
FIGS. 8A and 8B are perspective and side views
illustrating a magnetic field generating pole of a steel
strip stabilizing apparatus according to further another
10 embodiment of the present invention;
FIGS. 9A and 9B are a circuit diagram and a schematic
view illustrating a coil configuration in the magnetic
field generating pole of the steel strip stabilizing
apparatus according to the present invention;
15 FIGS. 10A to 10C are schematic views of a cooling
unit provided in the magnetic field generating pole or an
apparatus support body in the steel strip stabilizing
apparatus according to the present invention;
FIGS. 11 and 12 are graphs illustrating a performance
20 curve of the steel strip stabilizing apparatus according to
the present invention; and
FIG. 13 is a graph illustrating a sensitive curve of
a thickness and applied current of the steel strip
stabilizing apparatus according to the present invention.
25
Page 13
Mode for Invention
Exemplary embodiments of the present invention will
now be described in detail with reference to the
accompanying drawings.
5 FIGS. 2 to 4 are schematic view of a steel strip
stabilizing apparatus 1 according to the present invention.
As shown in FIG. 2, the steel strip stabilizing
apparatus 1 may perform shape correction and/or vibration
suppression in a plated steel strip 100 that is plated with
10 zinc by passing through a plating bath 110 of the zinc
plating equipment of FIG. 1 in the current embodiment.
Thus, the plating bath 110 including a sink roll 112 and a
stabilizing roll 114, a gas wiping device 120, and an upper
transfer roll 130 which are installed in a plating line
15 will be denoted by the reference numerals of FIG. 1
according to the related art.
Here, the shape correction in the steel strip may
represent a process in which a shape defect, which is bent
in a width direction, of the steel strip passing through
20 the gas wiping device 120, i.e., a C-curvature or Lcurvature
of the steel strip 100 is corrected to provide a
flat steel strip 100 passing through the gas wiping device
120, thereby preventing a plating deviation from occurring
in the steel strip 100.
25 Also, the vibration damping, i.e., vibration
Page 14
suppression of the steel strip 100 may represent a process
for preventing a phenomenon in which the steel strip is
abnormally controlled in plated thickness due to vibrations
of the transferred steel strip 100 while passing through
5 the gas wiping device 120.
Although it is described that the steel strip
stabilizing apparatus 1 of the present invention is applied
to a steel strip plating line, i.e., a zinc plating line of
the steel strip in this embodiment, the steel strip
10 stabilizing apparatus 1 may be applied to a continuous
production line along which the steel strip 100 is
continuously transferred when manufacturing the steel strip
100.
For example, the steel strip stabilizing apparatus
15 may also be applied to a steel strip surface treatment
process in which the shape defect such as the C-curvature
or L-curvature or vibrations may occur when the steel strip
travels to affect the production and quality of the steel
strip.
20 Also, the steel strip stabilizing apparatus 1 of the
present invention may be symmetrically disposed on both
sides of the traveling steel strip to realize uniform and
stable vibration damping of the steel strip.
However, the present invention is not limited thereto.
25 For example, the steel strip stabilizing apparatus 1 may
Page 15
only be provided on one side of the traveling steel strip.
At this time, (electro) magnetic force may be properly
controlled.
As shown in FIG. 2, at least one steel strip
5 stabilizing apparatus 1 may be disposed spaced a
predetermined distance S, for example, a distance S of
about 0.5 m to about 2 m upward from the gas wiping device
120 disposed above the plating bath 110.
For example, vibrations of the steel strip 100 in the
10 plating line may cause a plating deviation when an amount
of (zinc) plating solution on a surface of the steel strip
100 is reduced to control the plated thickness of the steel
strip 100 by wiping a gas in the gas wiping device 120.
Thus, the steel strip stabilizing apparatus 1 may be
15 disposed to be spaced upwardly from the gas wiping device
120 by the predetermined distance S to prevent the shape
defect or vibration of the steel strip 100 from occurring
when the gas wiping is performed.
Here, if beyond the above range, for example, the
20 distance S between the steel strip stabilizing apparatus 1
and the gas wiping device 120 is less than that of about
0.5 m, since the steel strip stabilizing apparatus 1 is
disposed very close to the gas wiping device 120, plating
solution scattering particles generated when wiping the gas
25 may be attached to the steel strip stabilizing apparatus 1
Page 16
to affect operation stability and accuracy of the steel
strip stabilizing apparatus 1.
On the other hand, if the distance S between the
steel strip stabilizing apparatus 1 and the gas wiping
5 device 120 is greater than that of about 2 m, since the
steel strip stabilizing apparatus 1 is disposed further
away from the gas wiping device 120, the shape correction
and vibration damping of the steel strip 100 in the gas
wiping region may be ineffective (insufficient).
10 As shown in FIG. 2, the steel strip stabilizing
apparatus 1 of the present invention may be (further)
disposed between a steel strip cooling device 150 for
cooling the plated steel strip 100 of which the plated
thickness is adjusted by wiping the gas, i.e., a mist
15 cooler and the upper transfer roll 130 disposed in the same
line as the stabilizing roll 114 for controlling the
traveling of the steel strip 100.
As shown in FIGS. 2 to 4, the steel strip stabilizing
apparatus 1 of the present invention may include an
20 apparatus support body 10 disposed on at least one side of
the traveling steel strip 100, i.e., the plated steel strip
100 traveling to pass through the plating bath 110,
preferably, both sides of the traveling steel strip 100 and
a steel strip stabilizing unit 30 including at least one
25 magnetic field generating pole 32 disposed on the apparatus
Page 17
support body 10 to face the steel strip 100 and a pole
expansion part 34 of the magnetic field generating pole
that is provided on a steel plate-side end of the magnetic
field generating pole 32 to increase electromagnetic or
5 magnetic attraction force with respect to the steel strip
100.
Thus, the steel strip stabilizing apparatus 1 of the
present invention may flatly correct the shape defect of
the steel strip 100 such as the C-curvature or L-curvature
10 or suppress or at least minimize vibrations of the steel
strip 100 in a non-contact manner using the (electro)
magnetic force, unlike the shape correction or vibration
damping of the steel strip using the existing mechanical
contact type roll, the gas spraying, or the simple magnet
15 block. As a result, the occurrence of the steel strip
surface detect or the inefficient shape correction or
vibration damping of the steel strip due to the gas
spraying in the contact manner according to the related art
may be removed.
20 Particularly, since the pole expansion part 34 is
provided, for example, in a so-called pole shoes shape
having a horizontal expansion surface in the traveling
direction of the steel strip 100 in the magnetic field
generating pole 32 for generating the (electro)magnetic
25 force that attracts the steel strip 100 to correct the
Page 18
shape of the steel strip 100 or suppress vibrations of the
steel strip 100, the steel strip 100 may be vary stably
corrected in shape or damped in vibrations even though the
steel strip is a thin film when compared to the steel strip
5 damping through the existing simple magnet block.
As shown in FIG. 3, the apparatus support body 10 may
have a plate shape lengthily extending in the traveling
direction of the steel strip 100. The apparatus support
body 10 may be manufactured by using a nonmagnetic material,
10 for example, ceramic or stainless steel (SUS) to prevent
the magnetic field from leaking when the (electro) magnetic
force is generated.
Although schematically shown in the drawings, the
apparatus support body 10 of the present invention 10 may
15 be fixedly connected to the whole equipment-side frame (not
shown) of the plating line.
Also, the apparatus support body 10 may be properly
adjusted in size according to the number of steel strip
stabilizing unit 30 to be installed. As shown in FIG. 3,
20 at least one apparatus support body 10 may be disposed in
the width direction of the steel strip 100 to generate the
steel strip attraction force in a region greater than at
least width of the steel strip 100 through the (electro)
magnetic force in the width direction of the steel strip
25 100.
Page 19
As shown in FIG. 3, in the steel strip stabilizing
apparatus 1 of the present invention, a pair of steel strip
stabilizing units 30 may be disposed on upper and lower
portions of the unit apparatus support body 10 lengthily
5 extending in the traveling direction of the steel strip 100,
and then, the unit apparatus support body 10 may be
disposed in a plurality of rows in the width direction of
the steel strip 100.
Here, the arrangement of the unit apparatus support
10 bodies 10 may vary in consideration of the thickness and
width of the steel strip 100.
As shown in FIG. 3, in the steel strip stabilizing
apparatus 1 of the present invention, the pole expansion
part 34 that is substantially provided in the magnetic
15 field generating pole 32 of the steel strip stabilizing
unit 30 for generating the (electro)magnetic attraction
force with respect to the steel strip 100 to expand a range
of a(n) (electro)magnetic effect with respect to the steel
strip 100 may be disposed to be parallel to the steel strip
20 100 by using a rounded part 36 integrally disposed on a
steel strip-side front end of the magnetic field generating
pole 32 as a medium.
That is, since the magnetic field generating pole
expansion part 34 of the present invention is provided as
25 an electromagnetic emission surface disposed parallel to
Page 20
the traveling steel strip 100 and is expanded in area
through the rounded part 36 of the front end of the
magnetic field generating pole 32, the magnetic fields
generated in the magnetic field generating pole 32 may be
5 uniformly emitted from the pole expansion part 34 onto the
entire area of the steel strip 100, thereby uniformly
providing strong attraction force on the whole.
Here, the pole expansion part 34 of the magnetic
field generating pole 32 of the present invention may be
10 integrally formed (processed) with the magnetic field
generating pole 32. Alternatively, if it is difficult to
integrally process the pole expansion part 34 and the
magnetic filed generating pole 32, an iron plate (a plate
material) that is a (ferro) magnetic body may be attached
15 to the magnetic field generating pole 32.
In the steel strip stabilizing apparatus 1 of the
present invention, the steel strip stabilizing unit 30 for
substantially realizing the shape correction and vibration
damping of the steel strip 100 may be provided in various
20 shapes as shown in FIGS. 4A and 4B.
That is, as shown in FIG. 4A, the steel strip
stabilizing unit 30 of the present invention may be
provided as a coil-type steel strip stabilizing unit 30a
including a core member 32a formed of a magnetic material
25 and an electromagnetic coil 32b wound around the core
Page 21
member 32a.
For example, the electromagnetic coil 32b for
generating electromagnetic force when current is applied
may be wound around the core member 32a that is
5 manufactured by laminating an SM45C-based material or a
silicon steel plate to constitute the magnetic field
generating pole 32. Here, the magnetic field generating
pole expansion part 34 may be vertically integrated with
the core member 32a.
10 As shown in FIG. 4A, in the coil-type steel strip
stabilizing unit 30a, the electromagnetic coil 32b wound
around the core member 32a may be surrounded by a cover
body 40, e.g., a nonmagnetic material that does not affect
the electromagnetic force such as synthetic resin or
15 stainless to prevent plating particles or foreign matters
from being inserted or accumulated between the coils.
Alternatively, as shown in FIG. 4B, the steel strip
stabilizing unit 30 of the present invention may be
provided as a magnet-type steel strip stabilizing unit 30b
20 in which the magnetic field generating pole 32 is provided
as a permanent magnet or electromagnet.
Here, as shown in FIGS. 4A and 4B, the pole expansion
part 34 provided in the magnetic field generating pole 32
may have a width D2 (e.g., a height in the traveling
25 direction of the steel strip 100) greater about one-and-a
Page 22
half times to about two times, preferably, about two times
than a diameter D1 of the electromagnetic coil 32b wound
around the core member 32b in the case of the coil-type
steel strip stabilizing unit 30a or a thickness D1 of the
5 magnetic field generating pole 32 in the case of the
magnet-type steel strip stabilizing unit 30b.
For example, if the width D2 of the pole expansion
part 34 is less than about one-and-a half times the
diameter or thickness D1 of the electromagnetic coil 32b or
10 the magnetic field generating pole 32, the strength of the
(electro) magnetic fields in the magnetic field generating
pole expansion part 34 may increase exiguously and thus be
equal to that in the vibration damping mechanism having the
block shape according to the related art. As a result,
15 steel strip attraction force per unit area, which is
generated by the magnetic field generating pole expansion
part 34 may excessively increase to increase stress
concentration in the steel strip 100. For example, in a
case in which the steel strip 100 is a thin film having a
20 thickness of about 0.6 t, the steel strip 100 may be dented.
On the other hand, if the width D2 of the pole
expansion part 34 is greater than about five times the
diameter or thickness D1 of the electromagnetic coil 32b or
the magnetic field generating pole 32, the magnetic field
25 generating pole expansion part 34 may excessively increase
Page 23
in area to reduce the (electro) magnetic effect, i.e., the
attraction force with respect to the steel strip 100. Thus,
it may be difficult to normally correct the shape of the
steel strip 100 or damp the vibration of the steel strip
5 100.
As shown in FIGS. 4A and 4B, a gap D3 between the
pole expansion parts 34 of the magnetic field generating
poles 32 of the upper and lower unit steel strip
stabilizing units may be about 20 mm to about 40 mm. For
10 example, if the gap D3 is less than about 20 mm, the pole
expansion parts 34 may be disposed very close to each other.
Thus, electromagnetic forces emitted from the magnetic
field generating pole expansion parts 34 may interfere with
each other to reduce the steel strip attraction force. On
15 the other hand, if the gap D3 is greater than about 40 mm,
unnecessary space may be occupied to increase the whole
size of the steel strip stabilizing apparatus 1.
As shown in FIG. 5, the steel strip stabilizing
apparatus 1 of the present invention may include sensors
20 for measuring a gap G between the steel strip stabilizing
unit 30, i.e., the magnetic field generating pole expansion
part 34 and the traveling steel strip 100, i.e., the plated
steel strip 100.
For example, as shown in FIG. 5, a known eddy current
25 sensor 50 provided in a sensor mounting hole 52 within an
Page 24
opening defined in the apparatus support body 10 and a
connection part 38 of the upper and lower magnetic field
generating pole 32 to measure the gap G by using the
strength of the magnetic fields may be used as the sensors.
5 Alternatively, a distance sensor 60, e.g., a laser
distance sensor connected to the apparatus support body 10
between the unit steel strip stabilizing units 30 may be
provided together with the eddy current sensor 50 or
independently provided to measure the gap G between the
10 magnetic field generating pole expansion part 34 and the
steel strip 100.
However, since the distance sensor 60 may easily
cause a measurement failure (error) in an actual plating
environment, the eddy current sensor 50 for detecting a
15 wavelength of the magnetic fields to detect eddy current
between the sensor and the steel strip 100, thereby
measuring the gap G may be used instead of the distance
sensor 60. Of cause, it is not impossible to use the
distance sensor 60.
20 The eddy current sensor 50 may detect a change in
impedance of the electromagnetic coil 32b according to a
change in magnetic field that interacts with a change in
distance between the sensor 50 and the steel strip 100
(actually, the gap G between the apparatus pole expansion
25 part 34 and the steel strip 100) to measure the gap G. A
Page 25
probe type sensor instead of an encircling type sensor
through which an object to be measured passes may be used
as the eddy current sensor 50 used in the present invention.
Here, in the case of using the distance sensor 60, a
5 cooling type distance sensor that is connected to the
apparatus support body 10 and allows coolant or air to flow
therein may be used as the distance sensor 60 because the
plating process of the present invention is performed at a
high temperature. For example, as shown in FIG. 5, the
10 distance sensor 60 may be disposed within a housing 62 of a
connecting rod 64 connected to the apparatus support body
10, and a window 66 may be disposed on a front side of the
distance sensor 60. Particularly, the distance sensor 60
may have a passage 62a through which the coolant or air is
15 introduced and discharged.
Also, the gap G between a front surface of the
expansion part 34 of the magnetic field generating pole 32
and the steel strip 100 may be defined within a measure
critical range in which the eddy current sensor 50 or the
20 distance sensor 60 is capable of measuring the gap G.
For example, the gap G that is capable of being
measured by using the eddy current sensor 50 may be in a
range of about 0.1 mm to about 44 mm. Here, the gap G may
not get out of the above range.
25 Also, to realize optimum vibration damping of the
Page 26
steel strip 100, the gap G may be properly adjusted
according to the previously known size, thickness, and
traveling speed of the steel strip 100.
FIGS. 6 to 8 are schematic views illustrating various
5 shapes of the steel strip stabilizing apparatus 1,
particularly, the steel strip stabilizing unit 30 according
to the present invention.
FIGS. 6A, 7A, and 8A illustrate the magnet-type steel
strip stabilizing unit 30b in which the magnetic field
10 generating pole 32 is provided as the permanent magnet or
electromagnet as shown in FIG. 4B. FIGS. 6B, 7B, and 8B
illustrate the coil-type steel strip stabilizing unit 30a
of FIG. 4A including the magnetic field generating pole 32
in which the electromagnetic coil 32b is wound around the
15 core member 32a.
That is, as shown in FIGS. 6A and 6B, the steel strip
stabilizing unit 30 of the present invention may have a “ ”
shape in which the upper and lower magnetic field
generating poles 32 are connected to each other by using
20 the connection part 38 as a medium.
In this case, even though the electromagnetic coil
32b is wound around each of the magnetic field generating
poles 32, the electromagnetic forces emitted from the
magnetic field generating poles 32 may be the same by the
25 connection part 38. Thus, current applied to each of the
Page 27
wound coils may be adjusted by one pulse width modulation
(PWM) driver and a control unit C connected to the PWM
driver. That is, even if current applied to the wound
coils is different, the electromagnetic forces (magnetic
5 fields) emitted from the magnetic field generating poles 32
may be the same.
However, as shown in FIGS. 7A and 7B, in the case in
which each of the upper and lower magnetic field generating
poles 32 is independently installed on the apparatus
10 support body 10 that is one nonmagnetic material to provide
a unit magnetic field generating pole having a “T” shape,
when current applied to the electromagnetic coil 32b wound
around the core member 32a by the PWM driver controlled by
the control unit C is differently controlled, the magnetic
15 forces emitted from the upper and lower magnetic field
generating poles 32 may be different.
As shown in FIGS. 8A and 8B, three magnetic field
generating poles 32 may be connected to the one apparatus
support body 10 by using a dual connection part 38 as a
20 medium, for example, the whole magnetic field generating
pole 32 may have an “E” shape when viewed from a front side.
In this case, as shown in FIG. 6, since the same
electromagnetic force is emitted from the whole magnetic
field generating pole 32, even though the electromagnetic
25 coil 32b is wound around only the intermediate core member
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32a, the electromagnetic forces (magnetic fields) generated
by the three magnetic field generating poles 32 may be the
same.
Thus, the steel strip stabilizing units 30 of FIGS. 6
5 to 8 having various shapes may be selectively used
according to the shape correction or vibration damping of
the steel strip 100. For example, the plurality of
magnetic fields generating poles of FIG. 8 may be used for
the condition in which the vibration of the steel strip 100
10 is relatively large according to the thickness or width of
the steel strip 100 or plating line. When it is necessary
to generate magnetic forces different from each other in
the magnetic field generating poles 32, the shape of FIG. 7
may be selected. Also, the shape of FIG. 6 may be provided
15 as a fundamental shape.
However, in any shape, as shown in FIGS. 6 to 8, the
plurality of magnetic field generating poles 32 may be
independently installed on the apparatus support body 10 in
the traveling direction of the steel strip 100 or installed
20 by using the connection part 38 as a medium. Here, the
plurality of magnetic field generating poles 32 may be
arranged in parallel with the steel strip 100 at the same
distance to provide uniform electromagnetic force.
Also, in the case of the plurality of magnetic field
25 generating poles 32 connected to each other by using the
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connection part 36 as a medium, one electromagnetic coil
32b may be wound to simplify a structure of the steel strip
stabilizing apparatus 1 as shown in FIG. 8.
As shown in FIGS. 9A and 9B, a plurality of
5 electromagnetic coils 32b of the coil-type steel strip
stabilizing unit 30a may be provided on the core member 32a
in parallel as shown in FIG. 4A when the core members 32a
of the magnetic field generating pole 32 are connected to
each other by using the connection part 38 as a medium.
10 That is, as shown in FIGS. 9A and 9B, when the
electromagnetic coils are provide on the core member in
parallel, applied current may be the same. Thus, the
electromagnetic forces generated in the magnetic field
generating poles 32 may be uniformly provided on the whole
15 to maintain uniform vibration damping performance.
Also, as shown in FIG. 2 , the steel strip stabilizing
apparatus 1 of the present invention may generate the
(electro) magnetic force on both sides of the traveling
plated steel strip 100 to attract the plated steel strip
20 100, thereby correcting the shape defect of the steel strip
100 or suppressing vibrations of the steel strip 100. That
is, in the case in which the vibration damping is performed,
the electromagnetic force may be controlled in real time.
Referring to FIG. 10, the steel strip stabilizing
25 apparatus 1 of the present invention may further include a
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cooling unit 70, i.e., a cooling medium flow type cooling
unit 70 provided in the magnetic field generating pole 32
including the permanent magnet, the electromagnet, or the
core member that is mounted on an apparatus support body
5 10’ of FIG. 10C or an apparatus support body 10 of FIGS.
10A and 10B.
For example, in the case of the zinc plated steel
strip 100 passing through the zinc plating bath 110 in FIG.
2, the zinc-molten solution may have a temperature of about
10 450°C to about 460°C. Thus, since the steel strip
stabilizing apparatus 1 disposed above the gas wiping
device may be exposed to the high temperature, the magnetic
field generating pole 32 may be maintained at least 150°C
to smoothly generate the (electro)magnetic force without
15 having an influence on the temperature.
That is, the apparatus support body or the magnetic
field generating pole may be cooled by allowing a nitrogen
gas or coolant to flow therein so that it prevent the at
least magnetic field generating pole from being reduced in
20 efficiency and from reaching a curie temperature at which
the (electro)magnetic force is weaken.
As shown in FIGS. 10A and 10B, the cooling unit 70 of
the present invention may have a hive-shaped cooling medium
passage 72 through which the coolant or nitrogen gas flows
25 into a rear end of the magnetic field generating pole 32
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(that is, the permanent magnet, the electromagnet, or the
core member). Also, cooling medium supply and discharge
tubes (not shown) are connected to one end and the other
end of the cooling unit 70, respectively.
5 Thus, the cooling medium may cool the magnetic field
generating pole 32 so that the magnetic field generation
pole 32 is maintained at the above-described temperature to
allow the magnetic field generating pole 32 to generate the
optimum electromagnetic force.
10 Here, a portion of the magnetic field generating pole
32 on which the cooling unit 70 is installed may have a
flange structure to connect a portion of a main body of the
magnetic field generating pole 32 to a portion of a rear
end of the magnetic field generating pole 32 so that the
15 steel strip stabilizing apparatus 1 is easily manufactured
and assembled.
That is, a rear portion of the magnetic field
generating pole 32 on which the cooling unit 70 is provided
may be provided as a separate assembly member.
20 For example, in a case in which a plate member formed
of a magnetic material is laminated to manufacture the core
member, a portion on which the cooling unit is disposed may
be integrally assembled in a flange shape.
Also, the magnetic field generating pole of the steel
25 strip stabilizing apparatus according to the present
Page 32
invention may expand a thickness of the apparatus support
body 10’ that is a separate member without providing the
cooling unit 70 to the core member of the permanent magnet,
the electromagnet, or the magnet (magnetic material). In
5 addition, the cooling medium passage 72 (although
schematically shown in FIG. 10C, it may have the shape as
shown in FIGS. 10A and 10B) may be formed in the apparatus
support body 10’ so that the nitrogen gas or coolant flows
to cool the apparatus support body 10’. Then, the nitrogen
10 gas or coolant may absorb heat of the magnetic field
generating pole to cool the magnetic field generating pole.
That is, in the case of installing the cooling unit
on the magnetic field generating pole, although it is
difficult to install the cooling unit, the cooling
15 efficiency may be improved. On the other hand, in the case
of installing the cooling unit in the apparatus support
body 10’ as shown in FIG. 10C, although it is easy to
install the cooling unit, the cooling efficiency may be
reduced. Thus, as necessary, the installation position of
20 the cooling unit may be properly selected. Also, all of
the cooling units of the magnetic field generating pole and
the apparatus support body as shown in FIGS. 10A to 10C may
be installed.
FIGS. 11 and 12 illustrate a performance curve of the
25 steel strip stabilizing apparatus according to the present
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invention. In FIGS. 11 and 12, an X-axis represents a gap
(see reference symbol G of FIG. 5) between the pole
expansion part 34 and the steel strip, and a Y-axis
represents steel strip attraction force that is determined
5 by the (electro)magnetic force.
Thus, when the gap is about 5 mm to about 40 mm, the
applied current is about 1.8 A, and the steel strip has
thicknesses of about 2 mm, 1 mm, and 0.5 mm as shown in FIG.
11, it is seen that the steel strip attraction force
10 according to the present invention increases in the entire
region of the gap when compared to that according to the
related art.
Also, when the gap is about 5 mm to about 40 mm, the
steel strip has a thickness of about 1 mm, and the applied
15 current is about 2A and 1A as shown in FIG. 12, it is seen
that the steel strip attraction force according to the
present invention further increases in the entire region of
the gap when compared to that according to the related art.
FIG. 13 illustrates a sensitive curve when the
20 applied current is about 0.1 A to about 1.8 A, the gap (see
reference symbol G of FIG. 5) between the above-described
apparatus and the steel strip is about 20 mm, and the steel
strip has a thickness of about 0 mm to about 2 mm and
applied current of about 0 A to about 2 A in the steel
25 strip stabilizing apparatus of the present invention.
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For example, when the steel strip has a thickness of
about 1.5 mm, and the applied current is about 1 A in FIG.
13, it is seen that the steel strip attraction force is
about 45 kgf. Also, it is seen that maximum steel strip
5 attraction force is about 55 kgf when the applied current
is about 2 A.
In the above-described steel strip stabilizing
apparatus 1, the (electro)magnetic force by which the steel
strip attraction force is determined may be controlled by
10 the number of installed magnetic field generating poles,
the shape (width) of the pole expansion part, the number of
electromagnetic coil wound around the core member, the
applied (bias) current applied to the electromagnetic coil,
and a control frequency when the current is applied.
15 That is, the dynamic properties of the (electro)
magnetic force may be adjusted in consideration of the
thickness or width of the steel strip or the traveling
speed of the steel strip to realize the optimum vibration
damping in the steel strip.
20
Industrial Applicability
According to the present invention, the steel strip
stabilizing apparatus may correct the shape failure of the
plated steel strip and/or suppress vibrations of the steel
25 strip by using the (electro) magnetic fields in the non-
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contact manner. Particularly, the (electro) magnetic
attraction force with respect to the steel strip may
further increase to more improve the shape correction and
vibration damping properties that may have an influence on
5 the plating deviation. Therefore, the plating deviation in
the steel strip may be prevented to ultimately improve the
quality of the plating on the steel strip.
While the present invention has been shown and
described in connection with the exemplary embodiments, it
10 will be apparent to those skilled in the art that
modifications and variations can be made without departing
from the spirit and scope of the invention as defined by
the appended claims.
15
Page 36

CLAIMS
Claim 1
A steel strip stabilizing apparatus comprising:
5 an apparatus support body disposed on at least one
side of a traveling steel strip; and
a steel strip stabilizing unit comprising a magnetic
field generating pole disposed on the apparatus support
body to face the steel strip and a pole expansion part
10 configured to provide steel strip attraction force to a
steel strip-side end of the magnetic field generating pole.
Claim 2
The steel strip stabilizing apparatus of claim 1,
15 wherein the pole expansion part of the steel strip
stabilizing unit has a size greater than a thickness of at
least the magnetic field generating pole by using a rounded
portion disposed on a front end of the magnetic field
generating pole as a medium.
20
Claim 3
The steel strip stabilizing apparatus of claim 1,
wherein at least one steel strip stabilizing unit is
disposed on the apparatus support body, and
25 at least one apparatus support body is arranged in a
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width direction of the steel strip.
Claim 4
The steel strip stabilizing apparatus of claim 1,
5 wherein the magnetic field generating pole is provided in
plurality on the apparatus support body, and
the plurality of magnetic field generating poles are
independently provided or connected to each other by using
a connection part as a medium in a traveling direction of
10 the steel strip on the apparatus support body.
Claim 5
The steel strip stabilizing apparatus of any one of
claims 1 to 4, wherein the steel strip stabilizing unit
15 comprises one of a coil-type steel strip stabilizing unit
of which the magnetic field generating pole is constituted
by a core member formed of a magnetic material and an
electromagnetic coil wound around the core member and a
magnet-type steel strip stabilizing unit of which the
20 magnetic field generating pole comprises a permanent magnet
or electromagnet to correct a shape of the steel strip or
suppress vibrations of the steel strip.
Claim 6
25 The steel strip stabilizing apparatus of claim 5,
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5
wherein the electromagnetic coil is wound around at least
one of the plurality of magnetic field generating poles
connected to each other by using the connection part as the
medium.
Claim 7
The steel strip stabilizing apparatus of claim 5,
wherein the pole expansion part disposed on the magnetic
field generating pole has a width greater about one-and-a
10 half times to about five times than a diameter of the
electromagnetic coil wound around the core member of the
coil-type steel strip stabilizing unit or than a thickness
of the magnetic field generating pole of the magnet-type
steel strip stabilizing unit.
15
Claim 8
The steel strip stabilizing apparatus of claim 5,
wherein the electromagnetic coil of the coil-type steel
strip stabilizing unit is provided on the core member in
20 parallel.
Claim 9
The steel strip stabilizing apparatus of any one of
claims 1 to 4, further comprising at least one of an eddy
25 current sensor and a distance sensor which are configured
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to measure a gap between the pole expansion part and the
steel strip.
Claim 10
5 The steel strip stabilizing apparatus of any one of
claims 1 to 4, further comprising a cooling unit provided
in one or all of the apparatus support body and the
magnetic field generating pole disposed on the apparatus
support body.
10
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