JPH0917561A - C-shaped coil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a C-shaped coil which can be operated without anxiety over a long time, by interposing insulation paper between adjacent electromagnetic steel plates to avoid overheating of an iron core. SOLUTION: A C-shaped coil is constituted of plurally superposed electromagnetic steel plates 3 of C-shaped iron core 4, side plate 10 of fastening water-cooled copper plates 6 and the iron core and through bolts 7. However, in the upper/lower iron cores 4 of an air gap 2, a pitch of the copper plate 6 is formed small as compared with in the center part. In a part of the upper/lower iron cores 4 of the air gap 2, a water-cooled copper-made coil 5 is wound, to generate magnetic flux inside the iron core and in a magnetic path of the air gap. A high frequency current is allowed to flow in the coil 5, to supply also cooling water 8. Insulation paper 11 is interposed between the electromagnetic steel plates 3 and also between the steel plate 3 and the water-cooled copper plate 6. Further the dimension of the steel plate 3 is made smaller than a water-cooled pipe 6 in the outside, to be made in the dimension of the center part electromagnetic steel plate 3 via stages. Thickness of the side plate 10 or of the water-cooled copper plate 6 near the side plate is formed larger than the thickness of the copper plate 6 near the center in accordance with a heating frequency.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a C-shaped coil such as an edge heater for heating an end portion of a plate material or a strip plate.

[0002]

2. Description of the Related Art When a plate material heated in a furnace or the like is conveyed to the next step, its end portion is cooled and its temperature falls below the central portion.
Regarding the temperature distribution in the plate width direction, uniformity is an important point in terms of quality when, for example, plating or rolling is performed in the next step. For this reason, an edge heater is used which heats the end portion of the plate material to make the temperature distribution in the plate width direction uniform.

Conventionally, a C-shaped edge heater shown in FIG. 2 is used as the edge heater, and the plate material 1 which is an object to be heated is installed between the air gaps 2. In the C-type edge heater, the magnetic path for passing the magnetic flux (the magnetic body and the air gap that form the magnetic circuit) is formed by combining the electromagnetic steel plates 3 into the C-type. In order to reduce iron loss (Joule heat generation), a plurality of electromagnetic steel sheets 3 are stacked on each other to form an iron core 4
Is configured. Further, in order to generate a magnetic flux, coils 5 that can be energized using water-cooled copper pipes are usually installed in the iron cores 4 above and below the gap. Further, in order to remove the heat generation amount caused by the iron loss due to the electromagnetic steel plates 3, a plurality of electromagnetic steel plates 3 are stacked.
Water-cooled copper plates 6 are provided at various places, and the whole is fastened with through bolts 7. A matching unit and a power source for supplying a high frequency current are connected to the coil 5 (not shown). Further, cooling water 8 is supplied to the inside of the coil 5 to remove the heat generation amount of the coil 5 due to a large current.

[0004]

By the way, the cross-sectional shape of the iron cores above and below the C-shaped coil gap installed above and below the plate material is rectangular due to the restriction that a plurality of electromagnetic steel sheets are stacked and assembled (see FIG. 2). (See section AA). Then, the C-shaped coil gap for passing the plate material is set to about 50 to 300 mm in consideration of the shape and the plateability of the plate material. Further, the induction heating utilizes an induction current generated inside the plate material when the magnetic flux passes through the gap from the inside of the iron core.

However, when the gap becomes wider, the magnetic flux becomes wider as compared with the core cross-sectional area as it approaches the center of the air gap. The spread magnetic flux penetrates the electromagnetic steel plate surface when returning to the iron core (when the magnetic flux enters the iron core).

Therefore, since the magnetic flux that should normally penetrate perpendicularly to the thickness direction of the electromagnetic steel plates has a certain angle, a large induced current flows through the electromagnetic steel plates, causing dielectric breakdown between the electromagnetic steel plates, and It causes the situation of heating. That is, the thickness of the electromagnetic steel sheet is made thinner than twice the thickness (penetration depth) of the induction current flowing in the thickness direction of the electromagnetic steel sheet. By selecting the plate thickness in this way, the heat generation amount (iron loss) in the electromagnetic steel plate can be reduced. However, when dielectric breakdown occurs between a plurality of magnetic steel sheets, iron loss increases due to the same effect as that of using a magnetic steel sheet having a thickness of more than twice the penetration depth.

Explaining the cause of the heating, the C-shaped coil has a distribution of the magnetic field 9 as shown in FIG. 3 between the gaps. That is, since the gap is wide, the upper and lower iron cores 4 and 4 are bulged from the core cross-sectional area. Due to this bulge, the magnetic flux penetrates the core plate (portion a in the figure). The induced electromotive force in the electromagnetic steel plate and the copper plate due to the penetration of the magnetic flux applies a voltage to the extent that the insulating coating on the surface of the electromagnetic steel plate is broken.

[0008]

A structure of the present invention for solving the above-mentioned problems is to form a C-shape by stacking a plurality of electromagnetic steel sheets, and to wind a coil for passing a high-frequency current in the iron core portions above and below the air gap, In a device for sandwiching a plate material between air gaps for induction heating, insulating paper is sandwiched between the adjacent electromagnetic steel plates. Further, when the insulating paper is sandwiched in a portion where the magnetic field penetrates in the plate width direction surface of the electromagnetic steel plate,
Insulating paper can be used efficiently, which is preferable in terms of resource saving. Further, it is preferable that the pitch of the water-cooled copper plate is smaller than the pitch near the center outside the iron core. Further, it is preferable that the electromagnetic steel sheet between the water-cooled copper plates has a size smaller than that of the water-cooled copper plates. In addition, the size of the electromagnetic steel sheet between the water-cooled copper plates is made smaller than that of the water-cooled copper plate on the outside of the iron core.
It is preferable that the same size as that of the electromagnetic steel sheet in the central portion is obtained through the three stages.

According to the above construction, the magnetic flux bulging in the gap of the C-shaped coil enters the upper and lower iron cores as shown in FIG. Therefore, an induced electromotive force is generated in the side plate and the electromagnetic steel plates close to the side plate. However, since the insulating paper is sandwiched between the side plates and the electromagnetic steel sheets one by one, it is possible to exert an action of preventing dielectric breakdown between the electromagnetic steel sheets and subsequent heating due to an increase in induced current. Further, since the pitch of the water-cooled copper plate is smaller than that at the center on the outside where the magnetic flux is easily concentrated, the magnetic flux shielding effect and the cooling performance can be improved. Further, since the size of the electromagnetic steel plate is smaller than that of the water-cooled copper plate outside the iron core portion, the magnetic flux shielding effect is synergized and the heating of the electromagnetic steel plate can be prevented.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings.

As shown in FIG. 1, the outer shape of the C-shaped coil according to the present invention is such that a C-shaped iron core 4 is attached to an electromagnetic steel plate 3.
Stacked sheets, water-cooled copper plate 6 and side plate 1 for tightening the iron core
It is the same as the conventional one shown in FIG. 2 in that it is configured with 0 and through bolts 7. However, in the present invention, as shown in FIG. 4, in the iron cores 4 above and below the air gap 2, the pitch of the outer water-cooled copper plate 6 is made smaller than that in the central portion. Furthermore,
As shown in FIGS. 1 and 5, the size of the electromagnetic steel plate 3 is made smaller than that of the water-cooled copper plate 6 on the outer side, and after the steps (two steps in the illustrated example), the size of the central electrode steel plate 3 is obtained.

Further, a water-cooled copper coil 5 is wound around the iron core 4 above and below the air gap 2 to generate a magnetic flux (magnetic field) inside the iron core and in the magnetic path in the air gap.

Further, a matching device for passing a high frequency current and a high frequency power source are connected to the coil 5 (not shown).
Further, cooling water 8 is also supplied.

In the present invention, as shown in FIG.
In addition to the structure in which a plurality of electromagnetic steel plates 3 are stacked, an insulating paper 11 is sandwiched between the electromagnetic steel plates 3 and between the electromagnetic steel plates 3 and the water-cooled copper plate 6.

Specifically, the above configuration is adopted only in the portion 13 (see FIG. 3) through which the magnetic field penetrates the plate width direction surface of the electromagnetic steel plate 3.

Because of this structure, the core cross section 35
When there is no insulating paper 11 between the electromagnetic steel plates 3 forming the iron core 4 with a C-shaped coil of 0 mm × 200 mm and an input power of about 1000 Kw and a heating frequency of 500 Hz, the magnetic flux at the tip of the iron core near the air gap 2 penetrates. Overheat occurred at the position and it was not possible to apply all the power. However, the insulating paper 11 is sandwiched between one sheet and one sheet between the electromagnetic steel plates 3, the pitch of the water-cooled copper plate 6 is made smaller outside the iron core 4, and the outer electromagnetic steel plate 3 is made smaller than the water-cooled copper plate 6 to make it 2-3. C of the present invention in which the central electromagnetic steel plate 3 is made substantially equal to the water-cooled copper plate 6 through the step size.
The type coil could be operated without problems under the above conditions.

[0017]

As described above, according to the present invention, a plurality of magnetic steel sheets are stacked to form a C-shape, a coil for passing a high frequency current is wound around the iron core portions above and below the air gap, and a plate material is provided between the air gaps. In the device for sandwiching induction heating, since insulating paper is sandwiched between the adjacent electromagnetic steel plates, it is possible to prevent dielectric breakdown due to induced electromotive force between the electromagnetic steel plates that are stacked, and to prevent overheating of the iron core. By avoiding this, the C-shaped coil can be operated stably for a long time.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an iron core according to an embodiment of the present invention.

FIG. 2 is an external view of a conventional C-shaped coil.

FIG. 3 is an explanatory diagram of a magnetic flux distribution in an air gap.

FIG. 4 is an external view of a C-shaped coil according to the present invention.

FIG. 5 is a diagram illustrating a configuration on the outer side of the iron core according to the present invention.

[Explanation of symbols]

 1 plate material 2 air gap 3 electromagnetic steel plate 4 iron core 5 coil 6 water-cooled copper plate 7 through bolt 8 cooling water 9 magnetic field 10 side plate 11 insulating paper 13 part where magnetic field penetrates in the width direction of electromagnetic steel plate

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[Procedure amendment]

[Submission date] February 20, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction contents]

[0008]

A structure of the present invention for solving the above-mentioned problems is to form a C-shape by stacking a plurality of electromagnetic steel plates between water-cooled copper plates arranged at a predetermined pitch. In a device for winding induction coils by winding high-frequency currents around the cores above and below the gap, and sandwiching a plate material between the air gaps, insulating paper is sandwiched between the adjacent electromagnetic steel plates. Further, when the insulating paper is sandwiched by the magnetic field penetrating portion of the electromagnetic steel plate in the plate width direction, the insulating paper can be efficiently used, which is preferable in terms of resource saving. Further, it is preferable that the pitch of the water-cooled copper plate is smaller than the pitch near the center outside the iron core. Further, it is preferable that the electromagnetic steel sheet between the water-cooled copper plates has a size smaller than that of the water-cooled copper plates. Further, it is preferable that the size of the electromagnetic steel plate between the water-cooled copper plates is made smaller than that of the water-cooled copper plate outside the iron core, and the size of the electromagnetic steel plate at the center is the same as that of the water-cooled copper plate after a few steps. Ma
Also, depending on the frequency used for heating,
To reduce the magnetic flux penetrating the iron core, the thickness of the water-cooled copper plate
It is also preferable to change

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction contents]

As shown in FIG. 1, the outer shape of the C-shaped coil according to the present invention is such that a C-shaped iron core 4 is attached to an electromagnetic steel plate 3.
Stacked sheets, water-cooled copper plate 6 and side plate 1 for tightening the iron core
It is the same as the conventional one shown in FIG. 2 in that it is configured with 0 and through bolts 7. However, in the present invention, as shown in FIG. 4, in the iron cores 4 above and below the air gap 2, the pitch of the outer water-cooled copper plate 6 is made smaller than that in the central portion. Furthermore,
As shown in FIGS. 1 and 5, the size of the electromagnetic steel plate 3 is made smaller than that of the water-cooled copper plate 6 on the outer side, and after the steps (two steps in the illustrated example), the size of the central electrode steel plate 3 is obtained. Also,
The thickness of the side plate 10 or the water-cooled copper plate 6 close to the side plate is
Depending on the frequency, it is thicker than the thickness of the water-cooled copper plate 6 near the center.
Make

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hironori Fujioka 4-6-22 Kannon Shinmachi, Nishi-ku, Hiroshima City, Hiroshima Prefecture Mitsubishi Heavy Industries, Ltd. Hiroshima Works (72) Innovator Nobuo Iwama 2-4, Jonanjima, Ota-ku, Tokyo No. 3 Eguchi High Frequency Co., Ltd.

Claims (5)

[Claims] 1. A plurality of electromagnetic steel sheets are stacked between water-cooled copper sheets arranged at a predetermined pitch to form a C-shape, a coil for passing a high-frequency current is wound around iron core portions above and below the air gap, and a sheet material is sandwiched between the air gaps. In a device for induction heating, a C-shaped coil characterized in that insulating paper is sandwiched between the adjacent electromagnetic steel plates. 2. The C-shaped coil according to claim 1, wherein the insulating paper is sandwiched by a portion through which a magnetic field penetrates a plate width direction surface of an electromagnetic steel plate. 3. The C-shaped coil according to claim 1, wherein the pitch of the water-cooled copper plate is smaller on the outside of the iron core than the pitch near the center. 4. The C-shaped coil according to claim 1, wherein the electromagnetic steel sheet between the water-cooled copper plates has a size smaller than that of the water-cooled copper plates. 5. The size of the electromagnetic steel sheet between the water-cooled copper plates is made smaller than that of the water-cooled copper plate on the outside of the iron core part, and is made the same size as the electromagnetic steel plate at the center part through two to three steps.
Alternatively, the C-type coil according to item 3.