JPH08153577A - Induction heating device for metal plate - Google Patents

Abstract

PURPOSE: To make proper heating in the width direction while overheat in the edge part of a member to be heated is precluded and enhance the heating ability by lessening the leak of magnetic flux at inductors. CONSTITUTION: An induction heating device has inductors installed over and under about the width of a member to be heated which as a metal plate. The magnetic flux running from the core 11 of one inductor to the other's core 12 through material to be heated 101 is inclined with respect to its transported direction so that interlinkage with the material 101 is generated. On both sides in width direction of the material 101 closed loop is formed externally while penetrating the material 101 and also outer magnetic paths symmetrical to each other magnetically are formed, and the upper and lower cores 11B, 12B are made movable across the width of the material 101.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an induction heating device for heating a metal plate being conveyed in a hot rolling process, a cold rolling process or the like.

[0002]

2. Description of the Related Art Conventionally, the following three types of induction heating devices for heating steel sheets have been proposed. Solenoid type The solenoid type induction heating apparatus shown in FIG. 7 has been put to practical use as a strip heater for heating the full width of a magnetic steel sheet such as a general cold rolled steel sheet. In FIG. 7, (b) is a sectional view as seen from the side direction of (a), 101 is a material to be heated (steel plate), 102 is a heating coil (solenoid coil), and H ₀ is a magnetic field.

As shown in FIGS. 7B and 8, this strip heater produces an eddy current a over the entire width direction of the heated material 101, so that the current density along the width direction of the heated material 101 is reduced. The heating time of the edge portion b and the central portion of the material to be heated 101 is made uniform. Therefore, the material to be heated 101 can be heated substantially uniformly in the width direction. However, on the other hand, when heating a non-magnetic metal plate or a steel plate in a non-magnetic region at a high temperature (in a hot rolling process or a thick plate process), the magnetic flux does not concentrate on the heated material 101. However, there is a problem that a sufficient heating effect cannot be expected, and the temperature distribution in the width direction cannot be adjusted.

Further, in the hot rolling process or the like, it is possible to prevent the width and thickness of the material to be heated 101 from being various, and to prevent the heating coil 102 from colliding with the upper and lower warped portions of the front and rear ends of the heated material 101. In consideration of the above, it is necessary to increase the coil height H shown in FIG. 7B, and most of the magnetic flux generated by energization passes through the gap between the material to be heated 101 and the heating coil 102. , The heating capacity will be reduced more and more. As described above, the solenoid-type induction heating device can easily uniformly heat the material to be heated 101 in the width direction, but is poor in heating capacity and controllability of the temperature distribution in the width direction. It cannot be used to heat the steel sheet.

Linear Inductor Type Next, FIGS. 9 (a) and 9 (b) show Japanese Patent Laid-Open No. 63-128580.
1 shows an outline of a linear inductor type induction heating device shown in No. 1 and the like, which is capable of heating the material to be heated 101 being conveyed over its entire width. In this induction heating device, since the inductor composed of the heating coil 102 and the iron core 103 is arranged in the gap between the table rollers for transporting the material to be heated 101, the outer dimensions of these are restricted, and as a result, the heating coil 102 is embedded. There is a problem that the effective cross-sectional area of the iron core 103 is reduced and the reduction of heating capacity is unavoidable.

Further, as shown in FIG.
In order to prevent the upper warp and lower warp of 1 from colliding with the inductor, as the distance g between the upper and lower inductors is increased, the leakage flux between the magnetic poles of the iron core 103 increases and the heating flux rapidly increases. However, sufficient heating capacity cannot be obtained.

Transverse Flux Type FIG. 11 shows an outline of a transverse flux type induction heating apparatus, in which (b) is an enlarged main part of (a). In FIG. 11, 104 is an upper inductor, 105 is a lower inductor, H ₀ is a magnetic field, and φ is a magnetic flux. This type of induction heating device is widely used as an edge heater for heating an edge portion of a hot rolled steel plate, and is also used as a full width heater of a non-magnetic cold rolled steel plate in combination with an auxiliary heating device.

Regarding the hot rolling process, Japanese Patent Publication No. 1-26
No. 156, a plurality of inductors are arranged in the width direction of the material to be heated to compensate for the temperature drop at the front and rear ends of the material to be heated, and JP-B-62-14014 and JP-A-4-8910.
As in No. 9, a method of moving the transverse flux type inductor in the width direction of the material to be heated and heating the entire width has been proposed. However, these conventional transversal flux type induction heating devices, as in the linear inductor type, increase the distance between the upper and lower inductors as shown in FIG.
Similar to 0, there is a problem that the leakage magnetic flux between the iron core magnetic poles increases.

Further, the conventional transverse flux type induction heating apparatus has a drawback that a uniform temperature raising effect cannot be obtained in the width direction of the material to be heated. The reason is that the density distribution of the eddy current in this type of induction heating device is high at the edge portion of the heated material 101 as shown in FIG.
The overheating of the edge portion is remarkable. Note that FIG. 13 shows the eddy current a flowing through the heated material 101,
The edge portion b has a high density of the eddy current a, and the time during which the edge portion b is heated by the eddy current a during conveyance is longer than that in the central portion. In order to eliminate the drawback that it is difficult to make the width uniform, the following various proposals have been made.

A. As shown in FIG. 14, a wedge-shaped pole piece 106 is attached to a pole carrier 107.
The shape of the pole piece 106 is selected such that the material to be heated is slid along the dovetail-shaped hole 108 provided in the above according to the width of the material to be heated and the distance between the upper and lower inductors has a distribution in the width direction. Thus, the magnetic flux density is distributed so as to keep the magnetic flux density at the edge of the heated material low, and a uniform temperature distribution is obtained in the width direction of the heated material. However, in this method, when the thickness range of the material to be heated is large as in the hot rolling process, it is very difficult to select an appropriate pole piece 106 and there is a practical problem. There are inconveniences such as wear of moving parts.

B. As shown in FIG. 15, inductors each having a heating coil (not shown) arranged inside the iron core 103 are arranged above and below the material 101 to be heated (in the figure, the Only inductors are shown), these inductors are
According to the width W of 01, the link mechanisms 110 and 111 are rotated to heat the material to be heated 101 having various widths.

In this example, the lower inductor (heating coil) is arranged in the gap of the table roller for conveying the material to be heated, and this gap is required to convey the material 101 to be heated appropriately and appropriately. There is a restriction that it cannot be increased unnecessarily. Further, in this method, when the range of the minimum width to the maximum width of the material to be heated 101 is wide, the lower inductor (heating coil) has a wide rotation range, and thus it is necessary to make the gap between the table rollers extremely wide. It becomes an unrealistic facility.

C. As shown in FIG. 16, both edges of the material to be heated 101 are sandwiched by magnetic flux concentrating members 112 and 113 having a U-shaped cross section to penetrate the edge of the material to be heated 101. The magnetic flux generated is bypassed, and the eddy current induced in the edge portion is suppressed to prevent overheating of the edge portion. However, in this method, the U-shaped magnetic flux concentration members 112 and 113 are
The movement adjusting devices 114, 1 according to the width of the material 101 to be heated.
Since it is necessary to control the position by means of 15, the equipment becomes complicated and expensive. In addition, there is a problem in that it is not possible to cope with undulation, upward warp or downward warp of the material to be heated 101, and vertical movement during conveyance, as in the hot rolling process.

The present invention has been made to solve the above problems, and an object of the present invention is to prevent overheating of an edge portion of a material to be heated in a transverse flux type induction heating apparatus, and to make it suitable. Achieves heating in the width direction, and even when the distance between the upper and lower inductors is long, the magnetic flux leakage can be reduced and a sufficient heating effect can be obtained.
An object of the present invention is to provide an induction heating device having a simple structure and low cost, which is capable of coping with corrugation, warpage of a material to be heated, vertical movement during transportation, and the like.

[0015]

To achieve the above object, a first invention is an induction heating apparatus having inductors arranged above and below in a thickness direction so as to sandwich a material to be heated, which is a metal plate, The magnetic flux from the iron core forming one inductor to the iron core forming the other inductor via the material to be heated is inclined with respect to the conveying direction of the material to be heated and linked to the material to be heated.

A second invention is an induction heating apparatus having inductors arranged above and below in a thickness direction so as to sandwich a material to be heated, which is a metal plate, in the width direction of the material to be heated. To form a closed loop on the outside thereof and to form magnetically symmetrical external magnetic paths, and
The iron cores forming the upper and lower inductors are movable along the width direction of the material to be heated.

In the second invention, it is desirable that the iron cores constituting the upper and lower inductors are connected by a link mechanism forming a part of the external magnetic path, and the distance between the two iron cores can be varied by this link mechanism. .

[0018]

In the first aspect of the invention, the eddy current having the components shown in FIGS. 8 and 13 is generated in the material to be heated by the vertical component and the horizontal component of the magnetic flux that is inclined and interlinks with the material to be heated. As a result, it is possible to configure a heating device having the advantages of both the conventional solenoid type and the transverse flux type, and it is possible to perform heating in the width direction and improve the heating capacity.

In the second aspect of the invention, since the magnetically symmetrical external magnetic path that penetrates the material to be heated and forms a closed loop outside the material is formed, the iron cores of the upper and lower inductors are formed as in the conventional transverse flux type. Even when the distance is large, the leakage magnetic flux can be reduced and most of the generated magnetic flux can be used for heating the material to be heated. Further, if the upper and lower iron cores can be moved in the horizontal direction so that the center part of the material to be heated and the vicinity of the edge part have a difference in the number of interlinking magnetic fluxes, the overheating of the edge part is further prevented.

By combining the first invention and the second invention, the improvement of the heating capacity by eliminating the leakage magnetic flux is best achieved in the widthwise heating. Further, in the second invention, if a part of the external magnetic path is formed by a link mechanism and the upper and lower iron cores are configured to be movable in the thickness direction of the heated material by this link mechanism, Smooth transport and heating are possible regardless of thickness, warpage, and vertical movement.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a main part of an embodiment of the first invention described in claim 1, and iron cores (magnetic poles) of upper and lower inductors of a transverse flux type induction heating apparatus.
The positional relationship between 11, 12 and the material to be heated 101 is shown. The heating coils that form the upper inductor and the lower inductor are not shown.

In FIG. 1, iron cores 11 and 12 are arranged so as to sandwich a material 101 to be heated, which is conveyed in the direction of the arrow shown, from above and below with an appropriate gap. Further, the iron cores 11 and 12 are placed at positions such that the centers of the iron cores 11 and 12 are slightly displaced along the transport direction of the material to be heated 101, and the magnetic pole surfaces 11a and 12a are inclined by an angle θ with respect to the horizontal plane. In this state, the materials to be heated 101 are arranged so as to face each other. In other words, the iron cores 11 and 12 have a substantially wedge shape when viewed from the side, and the inclined magnetic pole surfaces 11 a and 12 a face each other with the heated material 101 therebetween.

With this structure, the iron core 11
The magnetic flux φ generated from the object is an angle (90 ° −
θ) interlinks and penetrates and reaches the iron core 12. That is, as shown in FIG. 2, the magnetic flux φ penetrating the heated material 101 is separated into a vertical component φ _V and a horizontal component (transport direction component) φ _H that are orthogonal to the heated material 101.

This means that the eddy current as shown in FIG. 8 by the solenoid type induction heating device and the eddy current as shown in FIG. 13 by the conventional transverse flux type induction heating device are induced. When the angle θ is changed, the ratio of the vertical component φ _V and the horizontal component φ _H of the magnetic flux φ changes. This makes it possible to weight which of the heating characteristics of the solenoid type and the conventional transverse flux type is dominant.

Here, although the vertical component φ _V has a sufficient heating capacity as in the conventional transverse flux type, it causes overheating of the edge portion of the material 101 to be heated. On the other hand, the horizontal component φ _H is effective for uniformly heating the entire width of the material to be heated 101 as in the solenoid type. Therefore, due to the heating effect that combines these two heating characteristics by the ratio of the vertical component φ _V and the horizontal component φ _H , compared with the conventional simple transverse flux formula, the material to be heated 10
Appropriate heating can be performed in the width direction of 1. In order to make the vertical component φ _V and the horizontal component φ _H equal in size, that is, to obtain substantially the same heating characteristics of the transverse flux type and the solenoid type, the angle θ should be set to about 45 °. Needless to say.

The shape and structure of the iron cores 11 and 12 are shown in FIG.
Even if it is not done as shown in FIG.
By making the facing surfaces of 2A parallel to the material 101 to be heated, although the number of interlinking magnetic flux with the material 101 to be heated is reduced, the same effect as above can be obtained. The conveyance direction of the heated material 101 and the direction of the magnetic flux φ in FIGS. 1 to 3 may be opposite.

Next, an embodiment of the second invention described in claim 2 will be described with reference to FIGS. 4 and 5. According to the above-described first invention, the uniform heating effect in the width direction can be enhanced as compared with the conventional case. However, since it is difficult to realize only with the first invention, it is intended to enhance the uniform heating effect by using the second invention described below together. The second invention has an effect of preventing overheating of the edge portion of the material to be heated and enhancing a uniform heating effect in the width direction even when alone without being combined with the first invention.

First, in FIG. 4, 11B is the iron core of the upper inductor, 12B is the iron core of the lower inductor, and 13, 1
Reference numeral 4 is a yoke for supporting these iron cores, 15 and 16 are link mechanisms made of a magnetic material, and 17 and 18 are yokes 13 and 1.
4 is a drive unit that drives 4 in the horizontal direction (width direction of the material to be heated 101) to move the iron cores 11B and 12B in the horizontal direction. The material to be heated 101 is conveyed in the front-back direction of the paper surface.

In the above structure, the driving portions 17 and 18 move the iron cores 11B and 12B horizontally and in the opposite directions above and below the material to be heated 101 to move the end portions of the iron cores 11B and 12B as shown in FIG. Heated material 10
It can be arranged at a position displaced from the edge portion 1 by the distance L. As a result, since only one iron core 11B or 12B exists above and below the edges of both ends of the material to be heated 101, it is possible to reduce the magnetic flux interlinking in the vicinity of the edges. Similar to Japanese Patent Publication No. 4-56093 described above, overheating can be prevented by reducing the eddy current density at the edge portion.

When the width of the material to be heated 101 is different, the amount of horizontal movement of the iron cores 11B and 12B may be adjusted appropriately. Further, the distance L may be adjusted according to the material of the material to be heated 101, thermal conductivity, and the like.

Further, as shown in FIG. 4, the iron cores 11B, 1B
2B, the yokes 13 and 14, and the link mechanisms 15 and 16 form a closed-loop external magnetic path that penetrates the heated material 101 and returns, and the external magnetic path is the heated magnetic material 10.
1 is magnetically symmetrical with respect to the width direction of 1. As a result, the magnetic flux penetrates the left and right halves of the material to be heated 101 almost uniformly, and the leakage magnetic flux as shown in FIG. 10 is reduced, so that the generated magnetic flux can be efficiently used for heating.

Further, the link mechanisms 15 and 16 can adjust the distance between the yokes 13 and 14, that is, the distance between the iron cores 11B and 12B, by their bending and stretching operations. Therefore, it is possible to set the optimum inter-core distance according to the thickness of the material to be heated 101. In addition, since it is not necessary to use a magnetic flux concentrating member as shown in FIG. 16, a space can be provided in the surrounding space of the heated material 101.
It is possible to cope with the waviness of 01, the warp, and the vertical movement during conveyance.

FIG. 6 shows the temperature distribution in the width direction of the material to be heated 101 when the embodiment of FIGS. 1 to 3 and the embodiments of FIGS. 4 and 5 are combined. As is apparent from the figure, according to the present invention, it is possible to prevent overheating in the vicinity of the edge portion of the material to be heated 101, and obtain a substantially uniform temperature distribution symmetrical to the center portion in the width direction.

[0034]

As described above, according to the first aspect of the present invention, in the transverse flux type induction device, the uniform heating action in the width direction can be improved as compared with the conventional case. Further, according to the second aspect of the present invention, it is possible to prevent overheating in the vicinity of the edge portion to obtain a more uniform heating action, and to improve the heating capacity and efficiency by reducing the leakage magnetic flux. At the same time, it is possible to deal with corrugation, warpage, and vertical movement of the material to be heated.

According to the first or second aspect of the present invention, it is possible to provide an induction heating apparatus having both excellent heating ability and widthwise heating ability, and a heat treatment technique for a hot rolled metal sheet or a non-magnetic metal sheet such as aluminum. It can be used for etc.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an embodiment of the first invention.

FIG. 2 is an explanatory view of the operation of the embodiment of FIG.

FIG. 3 is an explanatory diagram of another embodiment of the first invention.

FIG. 4 is an explanatory diagram of an embodiment of the second invention.

FIG. 5 is an explanatory view of the operation of the embodiment of FIG.

FIG. 6 is an explanatory diagram of an effect of the embodiment.

FIG. 7 is an explanatory diagram of a conventional technique.

8 is an explanatory diagram of an eddy current in the related art of FIG.

FIG. 9 is an explanatory diagram of a conventional technique.

FIG. 10 is an explanatory diagram of a leakage magnetic flux in the conventional technique of FIG.

FIG. 11 is an explanatory diagram of a conventional technique.

12 is an explanatory diagram of eddy current density and temperature distribution in the conventional technique of FIG.

FIG. 13 is an explanatory diagram of an eddy current in the related art of FIG.

FIG. 14 is an explanatory diagram of a conventional technique.

FIG. 15 is an explanatory diagram of a conventional technique.

FIG. 16 is an explanatory diagram of a conventional technique.

[Explanation of symbols]

 11, 11A, 11B Upper inductor iron core 11a, 12a Magnetic pole face 12, 12A, 12B Lower inductor iron core 13,14 Yoke 15,16 Link mechanism 17,18 Drive part 101 Heated material

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuhiro Taguchi 1-1-1 Tanabe Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa Fuji Electric Co., Ltd.

Claims (3)

[Claims] 1. An induction heating apparatus having inductors arranged above and below in a thickness direction so as to sandwich a material to be heated, which is a metal plate, in which an iron core constituting one inductor is connected to another inductor via a material to be heated. An induction heating device for a metal plate, characterized in that a magnetic flux directed to an iron core is inclined with respect to a conveying direction of a material to be heated so as to be linked to the material to be heated. 2. An induction heating apparatus having inductors arranged above and below in the thickness direction so as to sandwich a material to be heated, which is a metal plate, in which the material to be heated is penetrated on both sides in the width direction of the material to be heated. It is characterized in that a closed loop is formed on the outside thereof, external magnetic paths that are magnetically symmetrical to each other are formed, and that the iron cores that form the upper and lower inductors are movable along the width direction of the material to be heated. Induction heating device for metal plates. 3. The induction of a metal plate according to claim 2, wherein the iron cores constituting the upper and lower inductors are connected by a link mechanism forming a part of an external magnetic path, and the distance between the two iron cores is variable by this link mechanism. Heating device.