JP2020087734A - Induction heating device for steel plate - Google Patents

Abstract

A steel plate induction heating apparatus capable of reducing temperature variations in the width direction of a steel plate is provided. A steel sheet induction heating apparatus (1) includes a solenoid coil (50) and a first conductor short-circuit ring (10) arranged on the entry side or the exit side of the solenoid coil (50). The first conductor short-circuit ring 10 is arranged above the steel plate passing through the inside and extends in the width direction of the steel plate, and is arranged below the steel plate passing through the inside and extends in the width direction of the steel plate. At least one of the first ring upper portion and the first ring lower portion has a central portion located further from the solenoid coil than both end portions. [Selection drawing] Fig. 2

Description

TECHNICAL FIELD The present invention relates to an induction heating device, and more particularly, to an induction heating device for a steel plate having a steel plate passed inside.

The induction heating device for steel sheets is used as an alloying furnace in a production line for galvannealed steel sheets and various heat treatment furnaces. The induction heating device for steel sheets includes a solenoid coil. The solenoid coil is supplied with an electric current from a power source and generates a magnetic field. Electromagnetic induction due to the magnetic field of the solenoid coil is generated in the steel plate passing through the inside of the solenoid coil, and eddy current is generated. As a result, the steel plate generates heat and is heated.

By the way, in the induction heating device for steel plates, since the magnetic field concentrates on both ends of the steel plate in the width direction of the steel plate, the temperatures of both ends of the steel plate are likely to be higher than the temperature of the central part of the steel plate. It is preferable that variations in temperature of the steel sheet in the width direction can be suppressed as much as possible.

In an induction heating device for a steel plate, a technique for reducing the variation in temperature of the steel plate in the plate width direction is disclosed in JP-A-2-297892 (Patent Document 1) and JP-A-1-232685 (Patent Document 2). It is disclosed.

In the induction heating device for a steel sheet disclosed in Patent Document 1, it is possible to vary in the direction (coil height) perpendicular to the magnetic axis of the solenoid coil, measure the temperature of the steel sheet, and calculate the difference between the measurement result and the reference value. Adjust the coil height accordingly.

In the induction heating device disclosed in Patent Document 2, a plurality of magnetic flux adjusting rings are provided in the solenoid coil at both ends in the plate width direction of the steel plate passing through the inside. By the plurality of magnetic flux adjusting rings, the concentration of the magnetic field is relaxed at both ends of the steel plate passing through the inside of the solenoid coil in the plate width direction, and as a result, the temperature rise at both ends of the steel plate is suppressed.

JP-A-2-297892 JP-A-1-232685

In the case of the technique disclosed in Patent Document 1, it is considered that the height of the solenoid coil can be adjusted according to the thickness of the steel plate. However, it is considered that the temperature variation in the width direction of the steel sheet cannot be reduced in some cases.

In the case of the technique disclosed in Patent Document 2, the magnetic flux at the end portion in the width direction of the solenoid coil is reduced by the magnetic flux adjustment ring. Therefore, it is considered that the temperature variation in the width direction of the steel sheet can be reduced to some extent.

However, the temperature variation in the plate width direction of the steel sheet may be reduced by means other than the means disclosed in Patent Document 2.

An object of the present invention is to provide an induction heating device for a steel sheet, which can reduce temperature variations in the width direction of the steel sheet.

The steel plate induction heating device according to the present invention is a steel plate induction heating device for induction heating a steel plate,
A solenoid coil through which a steel plate passes
A first conductor short-circuit ring, which is disposed on the inlet side or the outlet side of the solenoid coil and through which the steel plate passes through;
The solenoid coil is
Located above the steel plate passing through the inside, the coil upper part extending in the plate width direction of the steel plate,
A coil lower part that is arranged below the steel plate passing through the inside and extends in the plate width direction of the steel plate,
When viewed in the sheet passing direction of the steel sheet, the coil left portion is arranged on the left side of the steel sheet passing through the inside and is connected to the coil upper portion and the coil lower portion,
When viewed in the sheet passing direction, the coil is disposed on the right side of the steel sheet passing through the inside, and includes the coil upper portion and the coil lower portion connected to the coil lower portion,
The first conductor shorting ring is
A first ring upper part that is arranged above the steel plate passing through the inside and extends in the plate width direction of the steel plate;
A first ring lower part that is arranged below the steel plate passing through the inside and extends in the plate width direction of the steel plate;
The first ring left part, which is arranged on the left side of the steel plate passing through the inside as viewed in the threading direction and is connected to the first ring upper part and the first ring lower part,
When viewed in the threading direction, the first ring right part, which is arranged to the right of the steel plate passing through the inside and is connected to the first ring upper part and the first ring lower part,
At least one of the upper portion of the first ring and the lower portion of the first ring is arranged such that the central portion in the plate width direction is farther from the solenoid coil than both ends in the plate width direction.

INDUSTRIAL APPLICABILITY The steel plate induction heating device according to the present invention can reduce temperature variations in the width direction of the steel plate.

FIG. 1 is a perspective view of an induction heating device for steel plates according to the first embodiment. FIG. 2 is a perspective view of an induction heating device for steel plates, which is a simplified view of the solenoid coil of FIG. 1. FIG. 3 is a view (front view) of the solenoid coil in FIG. 2 as seen in the sheet passing direction of the steel sheet. FIG. 4 is a view of the vicinity of the first conductor short-circuit ring of the induction heating device for steel plates in FIG. 2. FIG. 5 is a view of the first conductor short-circuit ring in FIG. 4 viewed in the sheet passing direction of the steel sheet. FIG. 6 is a perspective view of the first conductor short-circuit ring in FIG. FIG. 7 is a plan view (a view from above) in the vicinity of the first conductor short-circuit ring of the induction heating device for steel plates shown in FIG. 4. FIG. 8: is a schematic diagram which shows the position which the magnetic field formed of the solenoid coil sees from a sheet passing direction influences, when the induction heating apparatus for steel sheets is heating the steel sheet which is passing inside. FIG. 9: is a figure which shows the magnetic field strength in each position in the board width direction of a steel plate when the induction heating apparatus for steel plates is equipped with a solenoid coil, but is not equipped with the 1st conductor short circuit ring. FIG. 10 is a plan view (a view from above) in the vicinity of the first conductor short-circuit ring of the induction heating device for steel plates. FIG. 11 is a plan view of the vicinity of the first conductor short-circuit ring of the induction heating device for steel plates after a predetermined time has elapsed from FIG. 10. FIG. 12 is a plan view of the first conductor short-circuit ring having a shape different from that of FIG. 7. FIG. 13 is a perspective view of a first conductor short-circuit ring having a shape different from those of FIGS. 4 and 12. FIG. 14 is a perspective view of a first conductor short-circuit ring having a shape different from those of FIGS. 4, 12, and 13. FIG. 15 is a perspective view of a first conductor short-circuit ring having a shape different from those of FIGS. 4 and 12 to 14. FIG. 16 is a perspective view of a first conductor short-circuit ring having a shape different from those of FIGS. 4 and 12 to 15. FIG. 17 is a perspective view of a first conductor short-circuit ring having a shape different from those of FIGS. 4 and 12 to 16. FIG. 18 is a comparative view of a front view of the solenoid coil seen in the sheet passing direction RD and a front view of the first conductor short-circuit ring seen in the sheet passing direction. FIG. 19 is a perspective view of the induction heating device for steel plates according to the second embodiment. FIG. 20 is a perspective view of the induction heating device for steel plates according to the third embodiment. FIG. 21 is a front view of the periphery of the solenoid coil in FIG. 20 (a view seen from the sheet passing direction). 22 is a front view of the periphery of the solenoid coil when the solenoid coil height adjusting mechanism shown in FIG. 21 operates. FIG. 23 is a front view of the periphery of the first conductor short-circuit ring in FIG. 20 (a view seen from the sheet passing direction). FIG. 24 is a front view of the periphery of the first conductor short-circuit ring when the first conductor short-circuit ring height adjusting mechanism shown in FIG. 23 operates. FIG. 25 is a perspective view of the induction heating device for steel plates according to the fourth embodiment. FIG. 26 is a view of the vicinity of the second conductor short-circuit ring of the induction heating device for steel plates in FIG. 25. 27 is a view of the second conductor short-circuit ring in FIG. 26 as viewed in the sheet passing direction of the steel sheet. FIG. 28 is a perspective view of the second conductor short-circuit ring in FIG. 26. 29 is a perspective view of a second conductor short-circuit ring different from FIG. 28. FIG. 30 is a perspective view of a second conductor short-circuit ring different from FIGS. 28 and 29. FIG. 31 is a comparative view of a front view of the solenoid coil seen in the sheet passing direction RD and a front view of the second conductor short-circuit ring seen in the sheet passing direction. FIG. 32 is a plan view near the first conductor short-circuit ring. FIG. 33 is a plan view of the vicinity of the second conductor short-circuit ring. FIG. 34 is a diagram showing a temperature distribution in the width direction of the steel sheet on the outlet side of the steel sheet induction heating device when the steel sheet induction heating device shown in FIG. 25 is induction-heated. FIG. 35 is a diagram showing the relationship between L _EP /L _CP and the ratio of the temperature T _EP at the edge of the steel plate to the temperature T _{CP at the} center of the steel plate (that is, T _EP /T _CP ). FIG. 36 is a diagram showing the strength of the magnetic field H50 of the solenoid coil at the distance D _EP from the solenoid coil in the sheet passing direction. FIG. 37 is a perspective view of the induction heating device for steel plates according to the fifth embodiment. 38 is a front view of the vicinity of the second conductor short-circuit ring in FIG. 37 (a view seen from the sheet passing direction). FIG. 39 is a front view of the vicinity of the second conductor short-circuit ring when the second conductor short-circuit ring height adjusting mechanism shown in FIG. 38 operates.

The induction heating device for steel plates according to the present embodiment has the following configuration.
The induction heating device for steel sheet according to the configuration of (1) is an induction heating device for steel plate for induction heating a steel plate,
A solenoid coil through which a steel plate passes
A first conductor short-circuit ring, which is disposed on the inlet side or the outlet side of the solenoid coil and through which the steel plate passes through;
The solenoid coil is
Located above the steel plate passing through the inside, the coil upper part extending in the plate width direction of the steel plate,
A coil lower part that is arranged below the steel plate passing through the inside and extends in the plate width direction of the steel plate,
When viewed in the sheet passing direction of the steel sheet, the coil left portion is arranged on the left side of the steel sheet passing through the inside and is connected to the coil upper portion and the coil lower portion,
When viewed in the sheet passing direction, the coil is disposed on the right side of the steel sheet passing through the inside, and includes the coil upper portion and the coil lower portion connected to the coil lower portion,
The first conductor shorting ring is
A first ring upper part that is arranged above the steel plate passing through the inside and extends in the plate width direction of the steel plate;
A first ring lower part that is arranged below the steel plate passing through the inside and extends in the plate width direction of the steel plate;
The first ring left part, which is arranged on the left side of the steel plate passing through the inside as viewed in the threading direction and is connected to the first ring upper part and the first ring lower part,
When viewed in the threading direction, the first ring right part, which is arranged to the right of the steel plate passing through the inside and is connected to the first ring upper part and the first ring lower part,
At least one of the upper portion of the first ring and the lower portion of the first ring is arranged such that the central portion in the plate width direction is farther from the solenoid coil than both ends in the plate width direction.

In the solenoid coil for a steel plate, magnetic flux concentrates at both ends in the plate width direction of the steel plate passing through the inside. Therefore, in the width direction of the solenoid coil, the magnetic fields at both ends are stronger than the magnetic field at the center. Therefore, in the steel sheet induction heating device having the configuration (1), the first conductor short-circuit ring is arranged on the inlet side or the outlet side of the solenoid coil. As described above, at least one of the first ring upper part and the first ring lower part of the first conductor short-circuiting ring is arranged such that the central portion in the plate width direction of the steel plate is more distant from the solenoid coil than both ends thereof. That is, the first ring upper part and/or the first ring lower part has a convex shape. In this case, magnetic fields in opposite directions to the magnetic fields at both ends of the solenoid coil are generated at both ends in the width direction of the first conductor short-circuit ring, and the magnetic fields at both ends of the solenoid coil are weakened. As a result, variations in the magnetic field in the width direction of the solenoid coil are suppressed, and as a result, variations in temperature of the induction-heated steel sheet in the plate width direction can be suppressed.

The induction heating device for steel sheet according to the configuration of (2) is the induction heating device for steel sheet according to the description of (1),
In the first conductor short-circuit ring,
The central portion of the upper portion of the first ring is arranged farther from the solenoid coil than both end portions of the upper portion of the first ring,
The central portion of the first ring lower portion is arranged farther from the solenoid coil than both ends of the first ring lower portion.

In this case, in the first conductor short-circuit ring, not only the upper portion of the first ring but also the lower portion of the first ring has a convex shape, and the central portion is arranged farther from the solenoid coil than the both end portions. Therefore, magnetic fields in opposite directions to the magnetic fields at both ends of the solenoid coil are generated at both ends in the width direction of the first ring upper part and the first ring lower part of the first conductor short-circuit ring, and the magnetic fields at both ends of the solenoid coil are generated. Weaken. As a result, the variation of the magnetic field in the width direction of the solenoid coil is further suppressed, and as a result, the temperature variation of the induction-heated steel sheet in the plate width direction can be further suppressed.

The induction heating device for a steel sheet according to the configuration of (3) is the induction heating device for a steel sheet according to the description of (1) or (2),
At least one of the first ring upper part and the first ring lower part,
The central portion is arranged farther from the solenoid coil in the sheet passing direction than at both ends.

In the induction heating device for steel plates having the configuration of (3), the central portion can be arranged farther from the solenoid coil than both ends without using the space above or below the first conductor short-circuit ring. Therefore, the space above or below the induction heating device for steel plates can be used for the arrangement of equipment other than the first conductor short-circuit ring.

An induction heating device for a steel sheet having a configuration of (4) is the induction heating device for a steel sheet according to any one of (1) to (3),
The width of the first conductor short-circuit ring is within ±20% of the width of the solenoid coil,
The cross-sectional area of the first conductor short-circuit ring perpendicular to the plate passing direction is within ±20% of the cross-sectional area of the solenoid coil perpendicular to the plate passing direction.

In the induction heating device for steel plates having the configuration of (4), the magnetic fields formed at both ends in the width direction of the solenoid coil more effectively enter the first conductor short-circuit ring. Therefore, at both ends in the width direction of the first conductor short-circuit ring, magnetic fields opposite to the magnetic fields at both ends of the solenoid coil are more effectively generated, and the magnetic fields at both ends of the solenoid coil are further weakened.

An induction heating device for a steel sheet having a configuration of (5) is the induction heating device for a steel sheet according to any one of (1) to (4),
Of the solenoid coil, at least the coil left part and the coil right part are flexible conductors and can be bent,
The induction heating device for steel plate is further
Equipped with a solenoid coil height adjustment mechanism that can adjust the vertical distance between the coil upper part and the coil lower part,
Of the first conductor short-circuit ring, at least the first ring left portion and the first ring right portion are flexible conductors and are bendable,
The induction heating device for steel plate is further
A first conductor short-circuit ring height adjusting mechanism is provided that is capable of adjusting the vertical distance between the first ring upper part and the first ring lower part.

In the induction heating device for steel plates having the configuration of (5), the height (gap) of the first conductor short-circuit ring can be adjusted together with the height (gap) of the solenoid coil.

The induction heating device for steel sheet according to the configuration of (6) is the induction heating device for steel sheet according to any one of the configurations (1) to (5),
A second conductor short-circuit ring, which is arranged on the inlet side or the outlet side of the solenoid coil and through which the steel plate passes,
The solenoid coil is arranged between the first conductor short-circuit ring and the second conductor short-circuit ring,
The second conductor shorting ring is
A second ring upper part which is arranged above the steel plate passing through the inside and extends in the plate width direction,
A second ring lower part that is arranged below the steel plate passing through the inside and extends in the plate width direction,
A second ring left part, which is arranged on the left side of the steel plate passing through the inside as viewed in the threading direction and is connected to the second ring upper part and the second ring lower part,
The second ring right part, which is arranged on the right side of the steel plate passing through the inside as viewed in the threading direction and is connected to the second ring upper part and the second ring lower part,
At least one of the upper part of the second ring and the lower part of the second ring is arranged such that the center part in the width direction of the second conductor short-circuit ring is more distant from the solenoid coil than the both ends.

In the steel sheet induction heating device having the configuration (6), the first conductor short-circuit ring and the second conductor short-circuit ring are arranged on the inlet side and the outlet side of the solenoid coil. Therefore, the magnetic field at both ends of the solenoid coil can be weakened on both the inlet side and the outlet side of the solenoid coil. As a result, the variation of the magnetic field in the width direction of the solenoid coil is further suppressed, and as a result, the temperature variation of the induction-heated steel sheet in the plate width direction can be further suppressed.

The induction heating device for steel sheet according to the configuration of (7) is the induction heating device for steel sheet according to the description of (6),
In the second conductor short-circuit ring,
The central portion of the second ring upper portion is arranged farther from the solenoid coil than both ends of the second ring upper portion,
The central portion of the lower portion of the second ring is arranged farther from the solenoid coil than the end portions of the lower portion of the second ring.

In the induction heating device for steel sheet according to the configuration of (7), in the second conductor short-circuit ring, not only the upper portion of the second ring but also the lower portion of the second ring has a convex shape, and the central portion is a solenoid coil rather than both ends. It is located away from. Therefore, a magnetic field in the opposite direction to the magnetic field at both ends of the solenoid coil is generated at both ends in the width direction of the second ring upper part and the second ring lower part of the second conductor short-circuit ring, and the magnetic fields at both ends of the solenoid coil are generated. Weaken. As a result, the variation of the magnetic field in the width direction of the solenoid coil can be further suppressed, and the temperature variation of the induction-heated steel sheet in the plate width direction can be further suppressed.

An induction heating device for steel sheet according to the configuration of (8) is the induction heating device for steel sheet according to (6) or (7),
At least one of the second ring upper part and the second ring lower part,
The central portion is arranged farther from the solenoid coil in the sheet passing direction than at both ends.

In the induction heating device for steel plates having the configuration of (8), the central portion can be arranged farther from the solenoid coil than both ends without using the space above or below the second conductor short-circuit ring. Therefore, the space above or below the induction heating device for steel plates can be used for the arrangement of equipment other than the first conductor short-circuit ring.

An induction heating device for a steel sheet having a configuration of (9) is the induction heating device for a steel sheet according to any one of (6) to (8),
The width of the second conductor short-circuit ring is within ±20% of the width of the solenoid coil,
The cross-sectional area of the second conductor short-circuit ring perpendicular to the plate passing direction is within ±20% of the cross-sectional area of the solenoid coil perpendicular to the plate passing direction.

In the induction heating device for steel plates having the configuration of (9), the magnetic fields formed at both ends in the width direction of the solenoid coil more effectively enter the second conductor short-circuit ring. Therefore, magnetic fields in opposite directions to the magnetic fields at both ends of the solenoid coil are more effectively generated at both ends in the width direction of the second conductor short-circuit ring, and the magnetic fields at both ends of the solenoid coil are further weakened.

An induction heating device for a steel sheet having the configuration of (10) is the induction heating device for a steel sheet according to any one of (6) to (9),
In each of the first ring upper part, the first ring lower part of the first conductor short-circuit ring, the second ring upper part of the second conductor short-circuit ring, and the second ring lower part,
When the length in the plate width direction of the central portion is defined as the length L _CP and the length in the plate width direction of each end of both ends is defined as the length L _EP , the length L _CP and the length L _CP are defined. _EP satisfies the following formula (1).
L _EP /L _CP ≧0.46 (1)

In the steel sheet induction heating device having the configuration of (10), the magnetic fields in opposite directions to the magnetic fields at the both ends of the solenoid coil are more effectively generated at both ends in the width direction of the first conductor short-circuit ring and the second conductor short-circuit ring. Thus, the magnetic field at both ends of the solenoid coil can be further weakened.

An induction heating device for steel sheet according to the configuration of (11) is the induction heating device for steel sheet according to any one of (6) to (10),
In each of the first ring upper part, the first ring lower part of the first conductor short-circuit ring, the second ring upper part and the second ring lower part of the second conductor short-circuit ring,
A distance between the central portion and the solenoid coil in the sheet passing direction is defined as a distance D _CP , a distance between each end of both ends in the sheet passing direction and the solenoid coil is defined as a distance D _EP, and the solenoid When the vertical distance between the coil upper part and the coil lower part of the coil is defined as the distance G,
In each of the first ring upper part, the first ring lower part, the second ring upper part and the second ring lower part, the distance D _CP , the distance DE _P and the distance G satisfy the following expressions (2) and (3).
D _EP /D _CP <1.0 (2)
D _EP ≦1.2×G (3)

In the steel sheet induction heating device having the configuration of (11), the magnetic fields in opposite directions to the magnetic fields at the both ends of the solenoid coil are more effectively generated at both ends in the width direction of the first conductor short-circuit ring and the second conductor short-circuit ring. The magnetic field at both ends of the solenoid coil is further weakened.

An induction heating device for a steel sheet having a configuration of (12) is the induction heating device for a steel sheet according to any one of (6) to (11),
Of the second conductor short-circuit ring, at least the second ring left part and the second ring right part are flexible conductors and are bendable,
The induction heating device for steel plate is further
A second conductor short-circuit ring height adjusting mechanism is provided which is capable of adjusting the vertical distance between the second ring upper part and the second ring lower part.

In the induction heating device for steel plates having the configuration of (12), the height (gap) of the second conductor short-circuit ring can be adjusted.

Hereinafter, the induction heating device for steel plates according to the present embodiment will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts will be denoted by the same reference symbols and description thereof will not be repeated.

[First Embodiment]
[Structure of induction heating device 1 for steel plate]
FIG. 1 is a perspective view of an induction heating device for steel plates according to the first embodiment. The induction heating device for steel sheets can be used as, for example, one of an alloying furnace for galvannealed steel sheets and a heat treatment furnace for various steel sheets.

With reference to FIG. 1, the induction heating device for steel plates 1 includes a solenoid coil 50 and a first conductor short-circuit ring 10. In the following description, the inlet side of the steel sheet induction heating device 1 (that is, the front side of the steel sheet induction heating device) is denoted by “F”, and the outlet side of the steel plate induction heating device 1 (that is, the steel sheet induction heating device). The rear of 1) is indicated by "B". In FIG. 1, the steel plate SS progresses from the entrance side to the exit side of the induction heating device 1 for a steel plate. As shown in FIG. 1, the sheet passing direction of the steel plate SS (Steel Strip) is indicated by an arrow RD, and the plate width direction of the steel plate SS is indicated by an arrow TD. In addition, the normal direction of the plate surface of the steel plate SS (rolling vertical direction) is indicated by an arrow ND. The plate width direction TD of the steel plate SS corresponds to the width direction of the solenoid coil 50 and the first conductor short-circuit ring 10.

[Configuration of solenoid coil 50]
As shown in FIG. 1, the solenoid coil 50 is configured by spirally winding a conductor 51 a plurality of times. During induction heating, the steel plate SS passes through the inside of the solenoid coil 50. At the time of induction heating, the solenoid coil 50 is supplied with current from the power source 52 and generates a magnetic field. The magnetic field generates an eddy current in the steel plate SS, which causes Joule heat in the steel plate SS. This Joule heat heats the steel sheet SS (induction heating).

In order to simplify the drawing, in the following description, the solenoid coil 50 will be described as a housing as shown in FIG. With reference to FIG. 2, the solenoid coil 50 includes a coil upper portion 50U, a coil lower portion 50D, a coil left portion 50L, and a coil right portion 50R.

FIG. 3 is a view (front view) of the solenoid coil 50 in FIG. 2 viewed in the sheet passing direction of the steel plate SS. 2 and 3, the coil upper portion 50U is arranged above the steel plate SS passing through the inside of the solenoid coil 50 during induction heating, and extends in the plate width direction TD of the steel plate SS. The coil lower portion 50D is arranged below the steel plate SS that passes through the inside of the solenoid coil 50 during induction heating, and extends in the plate width direction TD of the steel plate SS.

The coil left portion 50L is arranged to the left of the steel plate SS passing through the inside of the solenoid coil 50 when viewed in the sheet passing direction RD (see FIG. 3 ). The coil left portion 50L is connected to the coil upper portion 50U and the coil lower portion 50D. Specifically, the upper end of the coil left portion 50L is connected to the left end of the coil upper portion 50U, and the lower end of the coil left portion 50L is connected to the left end of the coil lower portion 50D.

The coil right portion 50R is arranged to the right of the steel plate SS passing through the inside of the solenoid coil 50 when viewed in the sheet passing direction RD. The coil right part 50R is connected to the coil upper part 50U and the coil lower part 50D. Specifically, the upper end of the coil right part 50R is connected to the right end of the coil upper part 50U, and the lower end of the coil right part 50R is connected to the right end of the coil lower part 50D.

As shown in FIG. 3, the solenoid coil 50 has a rectangular shape when viewed in the sheet passing direction RD. However, the shape of the solenoid coil 50 as viewed in the sheet passing direction RD is not limited to the rectangular shape. Preferably, when viewed in the sheet passing direction RD, the coil upper part 50U and the coil lower part 50D are parallel to the plate width direction TD of the steel plate SS.

The conductor 51 forming the solenoid coil 50 may be a water cooling cable.

[Configuration of the first conductor short-circuit ring 10]
Referring to FIG. 2, the first conductor short-circuit ring 10 is made of a conductor and has a ring shape. That is, as will be described later, during induction heating, the first conductor short-circuit ring 10 is a closed loop.

In FIG. 2, the first conductor short-circuit ring 10 is arranged on the entrance side of the solenoid coil 50. However, as described later, the first conductor short-circuit ring 10 may be arranged on the outlet side of the solenoid coil 50.

FIG. 4 is a view of the vicinity of the first conductor short-circuit ring 10 in the induction heating device for steel plate 1 in FIG. 2. Referring to FIGS. 2 and 4, the first conductor short-circuit ring 10 includes a first ring upper portion 10U, a first ring lower portion 10D, a first ring left portion 10L, and a first ring right portion 10R.

FIG. 5 is a view of the first conductor short-circuit ring 10 in FIG. 4 seen in the sheet passing direction RD of the steel sheet SS. With reference to FIGS. 4 and 5, the first ring upper portion 10U in the first conductor short-circuit ring 10 is arranged above the steel plate SS passing through the inside of the first conductor short-circuit ring 10 at the time of induction heating. It extends in the width direction TD. The first ring lower portion 10D is arranged below the steel plate SS passing through the inside of the first conductor short-circuit ring 10 during induction heating, and extends in the plate width direction TD of the steel plate SS.

The first ring left portion 10L is arranged on the left side of the steel plate SS passing through the inside of the first conductor short-circuit ring 10 when viewed in the sheet passing direction RD. The first ring left portion 10L is connected to the first ring upper portion 10U and the first ring lower portion 10D. Specifically, the upper end of the first ring left part 10L is connected to the left end of the first ring upper part 10U, and the lower end of the first ring left part 10L is connected to the left end of the first ring lower part 10D.

The first ring right part 10R is arranged to the right of the steel plate SS passing through the inside of the first conductor short-circuit ring 10 as viewed in the sheet passing direction RD. The first ring right portion 10R is connected to the first ring upper portion 10U and the first ring lower portion 10D. Specifically, the upper end of the first ring right part 10R is connected to the right end of the first ring upper part 10U, and the lower end of the first ring right part 10R is connected to the right end of the first ring lower part 10D.

FIG. 6 is a perspective view of the first conductor short-circuit ring 10 in FIG. Referring to FIG. 6, first ring upper portion 10U includes a central portion CP (Center Portion) and both end portions. The central portion CP corresponds to the central portion in the width direction of the first ring upper portion 10U. Both ends correspond to both ends in the width direction of the first ring upper portion 10U. In addition, as described above, the width direction of the upper portion of the first ring is parallel to the plate width direction TD of the steel plate SS. Both end portions are configured by left and right end portions EP (Edge Portion). Similarly, the first ring lower portion 10D includes a central portion CP and both end portions formed of left and right end portions EP. Hereinafter, the two end portions EP are collectively referred to as both end portions EP.

In the first ring upper portion 10U and the first ring lower portion 10D, the central portion CP is a portion including the central position of the first ring upper portion 10U in the plate width direction TD. Both end portions EP are portions including both ends of the first ring upper portion 10U in the plate width direction TD. The central portion CP corresponds to the central portion in the width direction of the first ring lower portion 10D, and the both end portions EP correspond to the both end portions in the width direction of the first ring lower portion 10D. The central portion CP is arranged between both end portions EP.

FIG. 7 is a plan view (a view from above) in the vicinity of the first conductor short-circuit ring 10 of the induction heating device for steel plate 1 shown in FIG. With reference to FIG. 7, in the first ring upper portion 10U and the first ring lower portion 10D of the first conductor short-circuit ring 10, both end portions EP are arranged closer to the solenoid coil 50 than the central portion CP. Conversely, in the first ring upper portion 10U and the first ring lower portion 10D of the first conductor short-circuit ring 10, the central portion CP is arranged farther from the solenoid coil 50 than the both end portions EP.

The conductor forming the first conductor short-circuit ring 10 may be a water-cooled cable.

By arranging the first conductor short-circuit ring 10 having the above-described configuration on the inlet side or the outlet side of the solenoid coil 50, in the induction heating device for steel sheet 1 of the present embodiment, during induction heating, the sheet width direction of the steel sheet SS. It is possible to suppress the temperature of both end portions in the TD from becoming higher than the temperature of the central portion in the plate width direction TD, and it is possible to reduce the temperature variation in the steel plate SS in the plate width direction TD. Hereinafter, this point will be described.

FIG. 8 is a schematic diagram showing a magnetic field formed by the solenoid coil 50 as viewed in the sheet passing direction RD when the steel sheet induction heating device 1 is heating the steel sheet SS passing through the inside. Referring to FIG. 8, a coil upper portion 50U, a coil lower portion 50D, a coil left portion 50L, and a coil right portion 50R of the solenoid coil 50 each form a magnetic field by a current supplied from a power source 52 (see FIG. 1). To do. At this time, the central part of the steel plate SS in the plate width direction TD receives the magnetic fields of the coil upper part 50U and the coil lower part 50D. On the other hand, the left end SSLE of the steel plate SS (the broken line area in FIG. 8) receives not only the magnetic fields of the coil upper part 50U and the coil lower part 50D but also the magnetic field of the coil left part 50L. Further, the right end portion SSRE of the steel plate SS (broken line region in FIG. 8) receives not only the magnetic fields of the coil upper portion 50U and the coil lower portion 50D but also the magnetic field of the coil right portion 50R.

Therefore, if the induction heating device for steel plate 1 includes the solenoid coil 50 but does not include the first conductor short-circuit ring 10, each of the steel plates in the plate width direction TD obtained based on the Biot-Savart equation is obtained. The strength of the magnetic field at the position is as shown in FIG. 9, and in the plate width direction TD of the steel plate SS, the magnetic field increases as going from the central part to the end part. Therefore, in this case, the temperature distribution in the plate width direction TD of the steel plate SS is also the same as in FIG. 9. That is, in the plate width direction TD of the steel plate SS, the temperatures of both ends become excessively higher than the temperature of the central part, and the temperature varies in the plate width direction TD.

Therefore, in the steel sheet induction heating device 1 of the present embodiment, the first conductor short-circuit ring 10 is arranged on the inlet side or the outlet side of the solenoid coil 50. As described above, in the first ring upper portion 10U and the first ring lower portion 10D of the first conductor short-circuit ring 10, both end portions EP in the plate width direction TD are arranged closer to the solenoid coil 50 than the central portion CP. Therefore, in the region near the end portion EP, a magnetic field in a direction opposite to the magnetic field at both ends of the solenoid coil 50 in the plate width direction TD is generated, and the magnetic field at both ends of the solenoid coil 50 in the plate width direction TD is weakened. As a result, it is possible to suppress the variation in the magnetic field in the plate width direction TD and reduce the variation in the temperature of the steel plate SS in the plate width direction TD. Hereinafter, this point will be described in detail.

FIG. 10 is a plan view (a view from above) in the vicinity of the first conductor short-circuit ring 10 of the induction heating device for steel plates 1. With reference to FIG. 10, it is assumed that a current I50 flows in the coil upper portion 50U of the solenoid coil 50 from right to left in FIG. At this time, as shown in FIG. 10, a magnetic field H50 is generated. As described above, in the magnetic field H50, the magnetic fields H50 _{EP at} both ends in the plate width direction TD are larger than the magnetic field H50 _CP in the plate width direction TD. In FIG. 10, the magnitude of the magnetic field H50 is schematically shown by the length in the sheet passing direction RD.

As shown in FIG. 10, the magnetic field H50 _EP passes through both ends EP of the first ring upper portion 10U of the first conductor short-circuit ring 10. At this time, electromagnetic induction occurs in the first conductor short-circuit ring 10, and the induced current I10 is generated in the direction opposite to the current I50. Due to the generation of the induced current I10, as shown in FIG. 11, a magnetic field H10 is generated in the first conductor short-circuit ring 10. The magnetic field H10 has a vector opposite to that of the magnetic field H50 _EP . Therefore, the magnetic field H10 is offset a portion of the magnetic field H50 _EP, weaken the magnetic field H50 _EP.

On the other hand, the central portion CP of the first ring upper portion 10U of the first conductor short-circuit ring 10 is arranged farther from the solenoid coil 50 than the both end portions EP. Therefore, the magnetic field H10 generated in the central portion CP is either not reach the magnetic field H50 _CP in the central portion in the plate width direction TD of the solenoid, even arrived, as compared with the magnetic field H50 _EP at both ends, is less affected .. In other words, even as the magnetic field H10 generated in the central portion CP arrives to the magnetic field H50 _CP, influence of the magnetic field H10 generated in the central portion CP has on the magnetic field H50 _CP, the magnetic field H10 generated at both ends EP is the magnetic field H50 _EP Less than the impact. As a result, the magnetic field H50 _CP is not as weak as the magnetic field H50 _EP . 10 and 11, the magnetic field in the first ring upper portion 10U of the first conductor short-circuit ring 10 has been described, but the same mechanism occurs in the first ring lower portion 10D.

By the mechanism described above, the first conductor short-circuit ring 10 weakens the magnetic field H50 _EP at both ends while maintaining the strength of the magnetic field H50 _{CP at} the central portion in the plate width direction of the solenoid coil 50. Therefore, the variation of the magnetic field of the solenoid coil 50 in the plate width direction TD can be suppressed. As a result, in induction heating, it is possible to suppress variations in temperature in the plate width direction TD of the steel plate SS.

In the above description, the first ring upper portion 10U and the first ring lower portion 10D of the first conductor short-circuit ring 10 have the central portion CP extending in the plate width direction TD of the steel sheet and the same in the plate width direction TD as shown in FIG. 7. A pair of both end portions EP extending is included. However, the shapes of the first ring upper portion 10U and the first ring lower portion are not particularly limited as long as the central portion CP is arranged farther from the solenoid coil 50 than the both end portions EP.

FIG. 12 is a plan view of the first conductor short-circuit ring 10 having a shape different from that of FIG. 7. As shown in FIG. 12, the central portions of the first ring upper portion 10U and the first ring lower portion 10D may be formed to be convexly curved. Further, the shapes of the first ring upper portion 10U and the first ring lower portion 10D may be different.

In the above description, as shown in FIG. 7, both the first ring upper portion 10U and the first ring lower portion 10D of the first conductor short-circuit ring 10 have a convex shape, and the central portion CP is more than the end portions EP. It is arranged apart from the solenoid coil 50. However, as shown in FIG. 13, in the first ring upper portion 10U, the central portion CP has a convex shape, and the central portion CP is arranged farther from the solenoid coil 50 than both end portions EP, and the first ring lower portion 10D may be a linear shape extending in the plate width direction TD. Further, as shown in FIG. 14, the first ring lower portion 10D has a convex shape, and the central portion CP of the first ring lower portion 10D is arranged farther from the solenoid coil 50 than both end portions EP, and the first ring is formed. The upper portion 10U may have a linear shape extending in the plate width direction TD.

In the above description, the center portions CP of the first ring upper portion 10U and the first ring lower portion 10D of the first conductor short-circuit ring 10 are arranged farther in the plate passing direction RD than both end portions EP. However, the central portion CP may be arranged separately in a direction other than the plate passing direction RD. For example, as shown in FIG. 15, the central portion CP may be arranged apart from both end portions EP upward or downward (steel plate normal direction ND). Further, as shown in FIG. 16, the central portion CP may be arranged obliquely above or diagonally below both end portions EP. Further, as shown in FIG. 17, the arrangement position of the central portion CP of the first ring upper portion 10U and the arrangement position of the first ring lower portion 10D may be different.

Preferably, the central portions CP of the first ring upper portion 10U and the first ring lower portion 10D are arranged apart from both end portions EP in the plate passing direction RD. In this case, the central portion CP can be formed even if there is no space above or below the first conductor short-circuit ring 10. Further, since the central portion CP does not have to be formed above or below the first conductor short-circuit ring 10, other equipment can be arranged in the space above or below the first conductor short-circuit ring 10.

FIG. 18 is a comparison diagram of the front view of the solenoid coil 50 as viewed in the plate passing direction RD and the front view of the first conductor short-circuit ring 10 as viewed in the plate passing direction RD. Referring to FIG. 18, preferably, width T10 of first conductor short-circuit ring 10 is substantially the same as width T50 of solenoid coil 50. Here, “substantially the same” means that the width T10 is within the width T50±20%. The width T10 corresponds to the length of the first ring upper portion 10U and the first ring lower portion 10D in the plate width direction TD. The width T50 corresponds to the length of the coil upper portion 50U and the coil lower portion 50D in the plate width direction TD. Further, preferably, the cross-sectional area of the first conductor short-circuit ring 10 perpendicular to the sheet passing direction RD is equal to the cross-sectional area of the solenoid coil 50 perpendicular to the sheet passing direction RD. Here, the cross-section area of the first conductor short-circuit ring 10 perpendicular to the sheet passing direction RD is equivalent to the cross-section area of the solenoid coil 50 perpendicular to the sheet passing direction RD. The cross-sectional area perpendicular to the direction RD means within ±20% of the cross-sectional area perpendicular to the sheet passing direction RD of the solenoid coil 50. In this case, most of the magnetic field H50 generated in the solenoid coil 50 can pass through the first conductor short-circuit ring 10, and the magnetic flux density of the magnetic field H50 passing through the first conductor short-circuit ring 10 can be calculated as follows. Can be equivalent to As a result, the magnetic field H10 generated near the end EP of the first conductor short-circuit ring 10 can be strengthened, and the magnetic field H50 _EP near the end _EP of the solenoid coil 50 can be weakened more effectively.

As described above, the steel sheet induction heating device according to the present embodiment includes the first conductor short-circuit ring 10 on the inlet side or the outlet side of the solenoid coil. Then, in the first ring upper part 10U or the first ring lower part 10D of the first conductor short-circuit ring 10, the central part CP is arranged farther from the solenoid coil 50 than the both end parts EP. Therefore, in both end portions EP of the plate width direction TD of the first conductor short-circuit ring 10, the magnetic field H50 field of _EP and opposite H10 at both ends of the solenoid coil 50 is generated, the ends of the solenoid coil 50 the magnetic field H50 _EP Weaken. As a result, variations in the magnetic field H50 of the solenoid coil 50 in the plate width direction TD can be suppressed, and variations in temperature of the induction-heated steel plate SS in the plate width direction TD can be suppressed.

The induction heating device for steel plates according to the present embodiment includes the first conductor short-circuit ring 10 on the inlet side or the outlet side of the solenoid coil. If the conductor rings are provided at both ends in the width direction of the solenoid coil as in Patent Document 2, if the steel plate SS swings in the plate width direction TD when passing through the solenoid coil 50, the steel plate SS and the conductor ring are separated. May come into contact. However, in the induction heating device for steel plates according to the present embodiment, the first conductor short-circuit ring 10 is arranged on the inlet side or the outlet side of the solenoid coil. Hard to contact with 10.

[Second Embodiment]
In the first embodiment, the first conductor short-circuit ring 10 is arranged on the inlet side of the solenoid coil 50. However, as shown in FIG. 19, the induction heating device for steel sheet 1 according to the second embodiment includes the first conductor short-circuit ring 10 on the outlet side of the solenoid coil 50 and the first conductor short-circuit ring on the inlet side of the solenoid coil 50. Not equipped with 10. Even with the induction heating device 1 for a steel plate having such a configuration, the same effect as that of the first embodiment can be obtained.

[Third Embodiment]
FIG. 20 is a perspective view of the induction heating device for steel plates according to the third embodiment. 20, the induction heating device for steel sheet according to the third embodiment is different from the induction heating device for steel sheet according to the first embodiment in that a solenoid coil height adjusting mechanism 55 and a first conductor short-circuit ring height are provided. The adjusting mechanism 15 is provided.

[Configuration of solenoid coil height adjusting mechanism 55]
21 is a front view of the periphery of the solenoid coil 50 in FIG. 20 (a view seen from the sheet passing direction RD). Referring to FIG. 21, at least the coil left portion 50L and the coil right portion 50R of the solenoid coil 50 are flexible conductors and can be curved.

The solenoid coil height adjusting mechanism 55 includes a coil upper elevating device 55U and a coil lower elevating device 55D. The coil upper elevating device 55U moves up and down the coil upper part 50U. The coil upper elevating device 55U may have a known configuration as long as it can elevate the coil upper part 50U. The coil upper elevating device 55U includes, for example, a cylinder and a drive source that drives the cylinder. The coil lower elevating device 55D elevates and lowers the coil lower part 50D. The coil lower elevating device 55D may have a known configuration as long as it can elevate the coil lower part 50D. The coil lower elevating device 55D includes, for example, a cylinder and a drive source that drives the cylinder.

The solenoid coil height adjusting mechanism 55 adjusts the distance between the coil upper part 50U and the coil lower part 50D according to the plate thickness and material of the steel plate SS. As shown in FIG. 22, when the distance between the coil upper part 50U and the coil lower part 50D is narrowed, the coil upper elevating device 55U of the solenoid coil height adjusting mechanism 55 lowers the coil upper part 50U, and the coil lower elevating device 55D lowers the coil lower part. Go up 50D. At this time, the coil left part 50L and the coil right part 50R are curved, and the distance between the coil upper part 50U and the coil lower part 50D is narrowed. On the other hand, when increasing the distance between the coil upper part 50U and the coil lower part 50D, the coil upper elevating device 55U of the solenoid coil height adjusting mechanism 55 raises the coil upper part 50U and the coil lower elevating device 55D lowers the coil lower part 50D. .. As a result, the distance between the coil upper portion 50U and the coil lower portion 50D becomes wider.

The solenoid coil height adjusting mechanism 55 may include only one of the coil upper elevating device 55U and the coil lower elevating device 55D, or may have another configuration. The configuration of the solenoid coil height adjusting mechanism 55 is not particularly limited as long as the distance between the coil upper portion 50U and the coil lower portion 50D can be adjusted.

[Configuration of first conductor short-circuit ring height adjusting mechanism 15]
FIG. 23 is a front view of the periphery of the first conductor short-circuit ring 10 in FIG. 20 (a view seen from the sheet passing direction RD). Referring to FIG. 23, at least first ring left portion 10L and first ring right portion 10R of first conductor short-circuit ring 10 are flexible conductors and are bendable.

The first conductor short-circuit ring height adjusting mechanism 15 includes a first ring upper lifting device 15U and a first ring lower lifting device 15D. The first ring upper part elevating device 15U moves up and down the first ring upper part 10U. The first ring upper part elevating device 15U may have a known configuration as long as it can elevate the first ring upper part 10U. The first ring upper elevating device 15U includes, for example, a cylinder and a drive source that drives the cylinder. The first ring lower part elevating device 15D moves up and down the first ring lower part 10D. The first ring lower part elevating device 15D may have a known configuration as long as it can elevate the first ring lower part 10D. The first ring lower lifting device 15D includes, for example, a cylinder and a drive source that drives the cylinder.

The first conductor short-circuit ring height adjusting mechanism 15 adjusts the distance between the first ring upper part 10U and the first ring lower part 10D according to the plate thickness or the material of the steel plate SS. As shown in FIG. 24, when the distance between the first ring upper portion 10U and the first ring lower portion 10D is narrowed, the first ring upper lifting device 15U of the first conductor short-circuit ring height adjusting mechanism 15 moves the first ring upper portion 10U. It descends, and the first ring lower part lifting device 15D moves up the first ring lower part 10D. At this time, the first ring left part 10L and the first ring right part 10R are curved, and the distance between the first ring upper part 10U and the first ring lower part 10D is narrowed. On the other hand, when the distance between the first ring upper part 10U and the first ring lower part 10D is increased, the first ring upper part lifting device 15U of the first conductor short-circuit ring height adjusting mechanism 15 moves up the first ring upper part 10U, The 1-ring lower part lifting device 15D descends the 1st ring lower part 10D. This increases the distance between the first ring upper portion 10U and the first ring lower portion 10D.

The first conductor short-circuit ring height adjusting mechanism 15 may include only one of the first ring upper elevating device 15U and the first ring lower elevating device 15D, or may have another configuration. The configuration of the first conductor short-circuit ring height adjusting mechanism 15 is not particularly limited as long as the distance between the first ring upper portion 10U and the first ring lower portion 10D can be adjusted.

Preferably, the first conductor short-circuit ring height adjusting mechanism 15 follows the adjustment of the distance between the coil upper portion 50U and the coil lower portion 50D by the solenoid coil height adjusting mechanism 55 to follow the first ring upper portion 10U and the first ring. Adjust the distance between the lower parts 10D. In this case, even after adjusting the height of the solenoid coil 50, the height of the first conductor short-circuit ring 10 can be made the same as the height of the solenoid coil 50, and as a result, the first conductor short-circuit ring 10 can be made. The cross-sectional area perpendicular to the sheet passing direction RD can be adjusted to be substantially the same as the cross-sectional area perpendicular to the sheet passing direction RD of the solenoid coil 50.

[Fourth Embodiment]
FIG. 25 is a perspective view of the induction heating device for steel plates according to the fourth embodiment. The steel sheet induction heating device 1 of the fourth embodiment is newly provided with a second conductor short-circuit ring 20 on the outlet side of the solenoid coil 50 in addition to the configuration of the steel plate induction heating device 1 of the first embodiment. .. Other configurations are the same as those in the first embodiment. In short, the induction heating device for steel plates of the fourth embodiment is provided with conductor short-circuit rings (first conductor short-circuit ring 10 and second conductor short-circuit ring 20) on the inlet side and the outlet side of the solenoid coil 50.

FIG. 26 is a view of the vicinity of the second conductor short-circuit ring 20 in the steel sheet induction heating device 1 in FIG. 25. With reference to FIGS. 25 and 26, the configuration of the second conductor short-circuit ring 20 has the same configuration as the first conductor short-circuit ring 10. Specifically, the second conductor short-circuit ring 20 includes a second ring upper portion 20U, a second ring lower portion 20D, a second ring left portion 20L, and a second ring right portion 20R.

27 is a diagram of the second conductor short-circuit ring 20 in FIG. 26 as viewed in the sheet passing direction RD of the steel sheet SS. With reference to FIGS. 26 and 27, the second ring upper portion 20U in the second conductor short-circuit ring 20 is arranged above the steel plate SS that passes through the inside of the second conductor short-circuit ring 20 at the time of induction heating, and is a plate of the steel plate SS. It extends in the width direction TD. The second ring lower portion 20D is arranged below the steel plate SS that passes through the inside of the second conductor short-circuit ring 20 during induction heating, and extends in the plate width direction TD of the steel plate SS.

The second ring left portion 20L is arranged on the left side of the steel plate SS passing through the inside of the second conductor short-circuit ring 20 as viewed in the sheet passing direction RD. The second ring left portion 20L is connected to the second ring upper portion 20U and the second ring lower portion 20D. Specifically, the upper end of the second ring left portion 20L is connected to the left end of the second ring upper portion 20U, and the lower end of the second ring left portion 20L is connected to the left end of the second ring lower portion 20D.

The second ring right portion 20R is arranged to the right of the steel plate SS passing through the inside of the second conductor short-circuit ring 20 as viewed in the sheet passing direction RD. The second ring right portion 20R is connected to the second ring upper portion 20U and the second ring lower portion 20D. Specifically, the upper end of the second ring right part 20R is connected to the right end of the second ring upper part 20U, and the lower end of the second ring right part 20R is connected to the right end of the second ring lower part 20D. The conductor that constitutes the second conductor short-circuit ring 20 may be a water-cooled cable.

FIG. 28 is a perspective view of the second conductor short-circuit ring 20 in FIG. 26. With reference to FIG. 28, the second ring upper portion 20U includes a central portion CP and a pair of end portions EP (also referred to as both end portions EP). Similarly, the second ring lower portion 20D includes a central portion CP and both end portions EP.

In the second ring upper portion 20U and the second ring lower portion 20D, the central portion CP is a portion including the central position of the second ring upper portion 20U in the plate width direction TD. Both end portions EP are portions including both ends of the second ring upper portion 20U in the plate width direction TD. The central portion CP is arranged between both end portions EP.

In the second ring upper portion 20U and the second ring lower portion 20D of the second conductor short-circuit ring 20, both end portions EP are arranged closer to the solenoid coil 50 than the central portion CP. Conversely, in the second ring upper portion 20U and the second ring lower portion 20D of the second conductor short-circuit ring 20, the central portion CP is arranged farther from the solenoid coil 50 than the both end portions EP.

Similar to the first conductor short-circuit ring 10, the second conductor short-circuit ring 20 prevents both end portions of the steel sheet SS in the plate width direction TD from becoming higher than the central portion in the plate width direction TD during induction heating. .. The induction heating device for steel sheet 1 of the fourth embodiment includes a first conductor short-circuit ring 10 and a second conductor short-circuit ring 20 on the inlet side and the outlet side of the solenoid coil 50, and the solenoid coil 50 includes the first conductor short-circuit ring. 10 and the second conductor short-circuit ring 20. Therefore, the variation of the magnetic field in the plate width direction of the solenoid coil 50 can be further suppressed. Specifically, the magnetic field H50 _EP at both ends of the solenoid coil 50 in the plate width direction TD can be further weakened by the first conductor short-circuit ring 10 and the second conductor short-circuit ring 20, and the plate of the steel plate SS at the time of induction heating. The temperature variation in the width direction TD can be further reduced.

In the above description, as shown in FIG. 28, in both the second ring upper portion 20U and the second ring lower portion 20D of the second conductor short-circuit ring 20, the central portion CP has a convex shape and the central portion CP has both ends. It is arranged farther from the solenoid coil 50 than the portion EP. However, as shown in FIG. 29, the second ring upper portion 20U has a convex shape, the central portion CP is arranged farther from the solenoid coil 50 than both end portions EP, and the second ring lower portion 20D has a plate width. It may be a straight line extending in the direction TD. Further, the second ring lower portion 20D has a convex shape, the central portion CP is arranged farther from the solenoid coil 50 than the both end portions EP, and the second ring upper portion 20U has a linear shape extending in the plate width direction TD. May be

In the above description, the central portions CP of the second ring upper portion 20U and the second ring lower portion 20D of the second conductor short-circuit ring 20 are arranged farther in the plate passing direction RD than both end portions EP. However, the central portion CP may be arranged separately in a direction other than the plate passing direction RD. For example, as shown in FIG. 30, the center portion CP may be arranged apart from both end portions EP upward or downward (steel plate normal direction ND). Further, the central portion CP may be arranged apart from both end portions EP in an obliquely upper direction or an oblique lower direction. Further, the arrangement position of the central portion CP of the second ring upper portion 20U and the arrangement position of the second ring lower portion 20D may be different.

Preferably, the central portions CP of the second ring upper portion 20U and the second ring lower portion 20D are arranged apart from both end portions EP in the plate passing direction RD. In this case, since it is not necessary to form the central portion CP above or below the second conductor short-circuit ring 20, it is possible to arrange other equipment in the space above or below the second conductor short-circuit ring 20. it can.

FIG. 31 is a comparison diagram of the front view of the solenoid coil 50 as viewed in the plate passing direction RD and the front view of the second conductor short-circuit ring 20 as viewed in the plate passing direction. Referring to FIG. 31, preferably, width T20 of second conductor short-circuit ring 20 is substantially the same as width T50 of solenoid coil 50. Here, “substantially the same” means that the width T20 is within the width T50±20%. The width T20 corresponds to the length of the second ring upper portion 20U and the second ring lower portion 20D in the plate width direction TD. More preferably, the cross-sectional area of the second conductor short-circuit ring 20 perpendicular to the plate passing direction RD is equal to the cross-sectional area of the solenoid coil 50 perpendicular to the plate passing direction RD. Here, the cross-section area of the second conductor short-circuit ring 20 perpendicular to the sheet passing direction RD is equivalent to the cross-section area of the solenoid coil 50 perpendicular to the sheet passing direction RD. The cross-sectional area perpendicular to the direction RD means within ±20% of the cross-sectional area perpendicular to the sheet passing direction RD of the solenoid coil 50. In this case, most of the magnetic field H50 generated in the solenoid coil 50 can pass through the second conductor short-circuit ring 20, and the magnetic flux density of the magnetic field H50 passing through the second conductor short-circuit ring 20 can be calculated as the magnetic flux density in the solenoid coil 50. Can be equivalent to As a result, the magnetic field generated near the end EP of the second conductor short-circuit ring 20 can be strengthened, and the magnetic field H50 _EP near the end _EP of the solenoid coil 50 can be weakened more effectively.

[About preferred lengths of the central portion CP and each end portion EP]
Referring to FIG. 32, in the first ring upper portion 10U and the first ring lower portion 10D of the first conductor short-circuit ring 10, it is assumed that the central portion CP and both end portions EP extend parallel to the plate width direction TD. Then, the length of the central portion CP in the plate width direction TD is defined as the length L _CP, and the length of each of the end portions EP is defined as the length L _EP . Further, referring to FIG. 33, in the second ring upper portion 20U and second ring lower portion 20D of the second conductor short-circuit ring 20, it is assumed that the central portion CP and both end portions EP extend parallel to the plate width direction TD. To do. Then, the length of the central portion CP in the plate width direction TD is defined as the length L _CP, and the length of each of the end portions EP is defined as the length L _EP .

In short, referring to FIGS. 32 and 33, when the induction heating device for steel plate 1 includes the first conductor short-circuit ring 10 and the second conductor short-circuit ring 20, the first ring upper portion 10U of the first conductor short-circuit ring 10, In each of the first ring lower portion 10D, the second ring upper portion 20U of the second conductor short-circuit ring 20, and the second ring lower portion 20D, the length of the central portion CP in the plate width direction TD is defined as the length L _CP , When the length of each of the both end portions EP is defined as the length L _EP , the length of each of the first ring upper portion 10U, the first ring lower portion 10D, the second ring upper portion 20U, and the second ring lower portion 20D is L _CP and length L _EP satisfy the following expression (1).
L _EP /L _CP ≧0.46 (1)

FIG. 34 shows the output of the induction heating device for steel plate 1 when induction heating is performed on the steel plate using the induction heating device for steel plate 1 including the first conductor short-circuit ring 10 and the second conductor short-circuit ring 20 shown in FIG. 25. It is a figure which shows the temperature distribution of the steel plate SS in the plate width direction TD at the side. The temperature at the center position of the steel plate SS in the plate width direction TD is defined as temperature T _CP, and the temperature at the end point in the plate width direction TD is defined as temperature T _EP . In this case, as shown in FIG. 34, the temperature distribution of the steel plate SS in the plate width direction TD is lowest at the temperature T _CP at the central position in the plate width direction TD, and the temperature rises toward the end in the plate width direction TD. Then, the temperature becomes the highest at the temperature T _EP at the end point in the plate width direction TD.

FIG. 35 is a diagram showing the relationship between L _EP /L _CP and the ratio of the temperature T _EP at the edge of the steel plate to the temperature T _{CP at the} center of the steel plate (that is, T _EP /T _CP ). FIG. 35 is a ratio of the distance D _EP between each end EP and the solenoid coil 50 in the sheet passing direction RD to the distance D _CP between the central portion CP and the solenoid coil 50 in the sheet passing direction RD (that is, When D _EP /D _CP ) is less than 1.0 and the vertical distance between the coil upper portion 50U and the coil lower portion 50D of the solenoid coil 50 is defined as G, the distance D _EP is _equal to the distance G. It is the figure obtained by the steel plate temperature simulation based on the magnetic field calculation using the Biot-Savart equation when 1.2 times or less.

Referring to FIG. 35, preferably, if L _EP /L _CP is 0.46 or more, T _EP /T _CP is 1.10 or less, that is, the temperature T _EP of the steel plate end portion and the steel plate center portion The difference from the temperature T _CP becomes 10% or less, and the temperature variation in the plate width direction is further reduced. More preferably, L _EP /L _CP is 1.20 or more. In this case, the difference between the temperature T _EP at the edge of the steel plate and the temperature T _{CP at the} center of the steel plate is 5% or less (that is, T _EP /T _CP is 1.05 or less), and the temperature variation in the plate width direction is Further reduce. When L _EP /L _CP is 2.50 or more, T _EP /T _CP does not decrease so much even if L _EP /L _CP becomes high. Therefore, the preferable upper limit of L _EP /L _CP is 2.50.

[Distance between Central Part CP and Ends EP and Solenoid Coil 50]
32 and 33, the first ring upper part 10U of the first conductor short-circuit ring 10, the first ring lower part 10D, the second ring upper part 20U of the second conductor short-circuit ring 20, and the second ring lower part 20D. In each case, it is assumed that the central portion CP and both end portions EP extend parallel to the plate width direction TD. Then, the distance between the central portion CP and the solenoid coil 50 in the sheet passing direction RD is defined as D _CP, and the distance between each end EP in the sheet passing direction RD and the solenoid coil 50 is defined as D _EP . .. Further, the vertical distance between the coil upper portion 50U and the coil lower portion 50D of the solenoid coil 50 is defined as a distance G (see FIGS. 5 and 27). In this case, preferably, in each of the first ring upper portion 10U, the first ring lower portion 10D, the second ring upper portion 20U and the second ring lower portion 20D of the second conductor shorting ring 20, the distance D _{The CP} and the distance D _EP satisfy the following equations (2) and (3).
D _EP /D _CP <1.0 (2)
D _EP ≦1.2×G (3)

Figure 36 is a diagram showing the strength of the magnetic field H50 of the solenoid coil 50 at a distance D _EP from the solenoid coil 50 in the sheet passing direction RD. FIG. 36 is obtained by simulation based on Biot-Savart's law. Referring to FIG. 36, the strength of the magnetic field H50 becomes weaker as the distance from the solenoid coil 50 increases in the sheet passing direction RD. The magnetic field H50 at the position where the distance D _EP is 1.2 times the distance G is half the strength H _MAX of the magnetic field H50 when the distance D _EP is 0. If the distance _DEP is 1.2 times or less than the distance G, the magnetic field H50 passing through the first conductor short-circuit ring 10 and the second conductor short-circuit ring 20 becomes more than half, and the first conductor short-circuit ring 10 and the second conductor The effect of weakening the magnetic field H50 _EP at the end of the solenoid coil by the short-circuit ring 20 effectively functions. Therefore, as shown in the equation (3), the distance _DEP is preferably 1.2 times the distance G or less. If the distance D _CP is a little longer than the distance D _EP , the influence of the magnetic field generated in the central portion CP on the magnetic field H50 _CP is smaller than the influence of the magnetic fields generated at both end portions EP on the magnetic field H50 _EP. The effect of the present invention can be obtained. Therefore, the ratio of the distance D _EP to the distance D _CP is less than 1.0 as shown in the equation (2).

[Fifth Embodiment]
FIG. 37 is a perspective view of the induction heating device for steel plates according to the fifth embodiment. Referring to FIG. 37, the induction heating device for steel plate 1 according to the fifth embodiment is different from the induction heating device for steel plate 1 according to the third embodiment in that a second conductor short-circuit ring 20 and a second conductor short-circuit ring height are further added. And a height adjusting mechanism 25.

The configuration of the second conductor short-circuit ring 20 is the same as that of the fourth embodiment. Hereinafter, the second conductor short-circuit ring height adjusting mechanism 25 will be described.

[Configuration of second conductor short-circuit ring height adjusting mechanism 25]
FIG. 38 is a front view of the vicinity of the second conductor short-circuit ring 20 in FIG. 37 (a view seen from the sheet passing direction RD). Referring to FIG. 38, of the second conductor short-circuit ring 20, at least the second ring left portion 20L and the second ring right portion 20R are flexible conductors and can be curved.

The second conductor short-circuit ring height adjusting mechanism 25 has the same configuration as the first conductor short-circuit ring height adjusting mechanism 15. Specifically, the second conductor short-circuit ring height adjusting mechanism 25 includes a second ring upper elevating device 25U and a second ring lower elevating device 25D. The second ring upper part elevating device 25U elevates and lowers the second ring upper part 20U. The second ring upper part elevating device 25U may have a known configuration as long as it can elevate the second ring upper part 20U.

The second ring upper elevating device 25U includes, for example, a cylinder and a drive source that drives the cylinder. The second ring lower part elevating device 25D elevates and lowers the second ring lower part 20D. The second ring lower part elevating device 25D may have a known configuration as long as it can elevate the second ring lower part 20D. The second ring lower lifting device 25D includes, for example, a cylinder and a drive source that drives the cylinder.

The second conductor short-circuit ring height adjusting mechanism 25 adjusts the distance between the second ring upper portion 20U and the second ring lower portion 20D according to the thickness of the steel plate SS. As shown in FIG. 39, when the distance between the second ring upper portion 20U and the second ring lower portion 20D is reduced, the second ring upper lifting device 25U of the second conductor short-circuit ring height adjusting mechanism 25 moves the second ring upper portion 20U. The second ring lower part elevating device 25D descends and ascends the second ring lower part 20D. At this time, the second ring left portion 20L and the second ring right portion 20R are curved, and the distance between the second ring upper portion 20U and the second ring lower portion 20D is narrowed. On the other hand, when increasing the distance between the second ring upper portion 20U and the second ring lower portion 20D, the second ring upper portion elevating device 25U of the second conductor short-circuit ring height adjusting mechanism 25 moves up the second ring upper portion 20U, The second ring lower part lifting device 25D descends the second ring lower part 20D. As a result, the distance between the second ring upper portion 20U and the second ring lower portion 20D becomes wider.

The second conductor short-circuit ring height adjusting mechanism 25 may include only one of the second ring upper elevating device 25U and the second ring lower elevating device 25D, or may have another configuration. The structure of the second conductor short-circuit ring height adjusting mechanism 25 is not particularly limited as long as the distance between the second ring upper portion 20U and the second ring lower portion 20D can be adjusted.

Preferably, the second conductor short-circuit ring height adjusting mechanism 25, like the first conductor short-circuit ring height adjusting mechanism 15, adjusts the distance between the coil upper portion 50U and the coil lower portion 50D by the solenoid coil height adjusting mechanism 55. Following the above, the distance between the second ring upper portion 20U and the second ring lower portion 20D is adjusted. In this case, even after adjusting the height of the solenoid coil 50, the height of the second conductor short-circuit ring 20 should be the same as the height of the solenoid coil 50 together with the height of the first conductor short-circuit ring 10. As a result, the cross-sectional area of the second conductor short-circuit ring 20 perpendicular to the plate passing direction RD and the cross-sectional area of the first conductor short-circuit ring 10 perpendicular to the plate passing direction RD are calculated as follows. The cross-sectional area perpendicular to the RD can be adjusted to be almost the same.

The embodiments of the present invention have been described above. However, the embodiments described above are merely examples for implementing the present invention. Therefore, the present invention is not limited to the above-described embodiments, and can be implemented by appropriately modifying the above-described embodiments without departing from the spirit thereof.

DESCRIPTION OF SYMBOLS 1 Induction heating device for steel plate 10 1st conductor short-circuit ring 10U 1st ring upper part 10D 1st ring lower part 10L 1st ring left part 10R 1st ring right part 20 2nd conductor short-circuit ring 20U 2nd ring upper part 20D 2nd ring lower part 20L 2nd ring left part 20R 2nd ring right part 50 Solenoid coil 50U Coil upper part 50D Coil lower part 50L Coil left part 50R Coil right part CP Central part EP End, both ends SS Steel plate

Claims (12)

A steel plate induction heating device for induction heating a steel plate, comprising:
A solenoid coil through which the steel plate passes,
A first conductor short-circuit ring disposed inside or outside of the solenoid coil, the steel plate passing through the inside;
The solenoid coil is
Arranged above the steel plate passing through the inside, the coil upper part extending in the plate width direction of the steel plate,
A coil lower part that is arranged below the steel plate passing through the inside and extends in the plate width direction of the steel plate,
When viewed in the passing direction of the steel sheet, the coil left portion is arranged on the left side of the steel sheet passing through the inside, and is connected to the coil upper portion and the coil lower portion,
When viewed in the sheet passing direction, the coil is disposed on the right side of the steel sheet passing through the inside, and includes a coil right portion connected to the coil upper portion and the coil lower portion,
The first conductor shorting ring is
A first ring upper part that is arranged above the steel plate passing through the inside and extends in the plate width direction of the steel plate;
A first ring lower part that is arranged below the steel plate passing through the inside and extends in the plate width direction of the steel plate;
A first ring left part, which is arranged on the left side of the steel plate passing through the inside as viewed in the plate passing direction and is connected to the first ring upper part and the first ring lower part,
The first ring right part, which is arranged on the right side of the steel plate passing through the inside as viewed in the sheet passing direction and is connected to the first ring upper part and the first ring lower part,
At least one of the first ring upper portion and the first ring lower portion, the central portion is arranged farther from the solenoid coil than both end portions,
Induction heating device for steel sheet. The induction heating device for steel plate according to claim 1,
In the first conductor short-circuit ring,
The central portion of the first ring upper portion is arranged farther from the solenoid coil than both end portions of the first ring upper portion,
The central portion of the lower portion of the first ring is arranged farther from the solenoid coil than both end portions of the lower portion of the first ring,
Induction heating device for steel sheet. The induction heating device for steel sheet according to claim 1 or 2,
At least one of the first ring upper portion and the first ring lower portion,
The central portion is arranged farther from the solenoid coil in the plate passing direction than the both end portions are,
Induction heating device for steel sheet. The induction heating device for steel sheet according to any one of claims 1 to 3,
The width of the first conductor short-circuit ring is within ±20% of the width of the solenoid coil,
The cross-sectional area of the first conductor short-circuit ring perpendicular to the plate passing direction is within ±20% of the cross-sectional area of the solenoid coil perpendicular to the plate passing direction.
Induction heating device for steel sheet. The induction heating device for steel sheet according to any one of claims 1 to 4,
Of the solenoid coil, at least the coil left part and the coil right part are flexible conductors and can be curved,
Further, the induction heating device for steel plate,
A solenoid coil height adjusting mechanism capable of adjusting a vertical distance between the coil upper portion and the coil lower portion,
Of the first conductor short-circuit ring, at least the first ring left part and the first ring right part are flexible conductors and are bendable,
Further, the induction heating device for steel plate,
A first conductor shorting ring height adjusting mechanism capable of adjusting a vertical distance between the first ring upper part and the first ring lower part;
Induction heating device for steel sheet. The induction heating device for a steel sheet according to claim 1, further comprising:
A second conductor short-circuit ring, which is arranged on the inlet side or the outlet side of the solenoid coil and through which the steel plate passes through;
The solenoid coil is disposed between the first conductor short-circuit ring and the second conductor short-circuit ring,
The second conductor shorting ring is
A second ring upper part that is disposed above the steel plate passing through the inside and extends in the plate width direction;
A second ring lower part that is disposed below the steel plate passing through the inside and extends in the plate width direction;
A second ring left part, which is arranged on the left side of the steel plate passing through the inside as viewed in the plate passing direction and is connected to the second ring upper part and the second ring lower part,
When viewed in the sheet passing direction, the second ring right portion, which is arranged on the right side of the steel sheet passing through the inside and is connected to the second ring upper portion and the second ring lower portion,
At least one of the second ring upper portion and the second ring lower portion, the central portion is arranged farther from the solenoid coil than the both end portions,
Induction heating device for steel sheet. The induction heating device for steel sheet according to claim 6,
In the second conductor short-circuit ring,
The central portion of the second ring upper portion is arranged farther from the solenoid coil than the both ends of the second ring upper portion,
The central portion of the second ring lower portion is arranged farther from the solenoid coil than the both ends of the second ring lower portion,
Induction heating device for steel sheet. The induction heating device for steel plate according to claim 6 or 7,
At least one of the second ring upper portion and the second ring lower portion,
The central portion is arranged farther from the solenoid coil in the plate passing direction than the both end portions are,
Induction heating device for steel sheet. The induction heating device for steel sheet according to any one of claims 6 to 8,
The width of the second conductor short-circuit ring is within ±20% of the width of the solenoid coil,
The cross-sectional area of the second conductor short-circuit ring perpendicular to the plate passing direction is within ±20% of the cross-sectional area of the solenoid coil perpendicular to the plate passing direction.
Induction heating device for steel sheet. The induction heating device for a steel sheet according to any one of claims 6 to 9,
In each of the first ring upper part of the first conductor shorting ring, the first ring lower part, the second ring upper part of the second conductor shorting ring, and the second ring lower part,
When the length of the central portion in the plate width direction is defined as the length L _CP and the length of each end of the both ends is defined as the length L _EP , the length L _CP and the length L _EP satisfies the following formula (1),
Induction heating device for steel sheet.
L _EP /L _CP ≧0.46 (1) The induction heating device for a steel sheet according to any one of claims 6 to 10,
In each of the first ring upper part, the first ring lower part, the second ring upper part and the second ring lower part of the second conductor shorting ring of the first conductor shorting ring,
The distance between the central portion and the solenoid coil in the sheet passing direction is defined as a distance D _CP, and the distance between each end of the both ends in the sheet passing direction and the solenoid coil is the distance D _{CP. When EP} is defined and the vertical distance between the coil upper part and the coil lower part of the solenoid coil is defined as a distance G,
In each of the first ring upper part, the first ring lower part, the second ring upper part and the second ring lower part, the distance D _CP , the distance DE _P and the distance G are expressed by the following formula (2) and formula. Satisfy (3),
Induction heating device for steel sheet.
D1 _EP /D1 _CP <1.0 (2)
D1 _EP ≦1.2×G1 (3) The induction heating device for a steel plate according to any one of claims 6 to 11,
Of the second conductor short-circuit ring, at least the second ring left part and the second ring right part are flexible conductors and are bendable,
Further, the induction heating device for steel plate,
A second conductor short-circuit ring height adjusting mechanism capable of adjusting a vertical distance between the second ring upper part and the second ring lower part;
Induction heating device for steel sheet.

Images